x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

38 files changed, 25114 insertions, 0 deletions

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
new file mode 100644
index 000000000..aa11bcefd
--- /dev/null
+++ b/drivers/hv/Kconfig
@@ -0,0 +1,113 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "Microsoft Hyper-V guest support"
+
+config HYPERV
+	bool "Microsoft Hyper-V core hypervisor support"
+	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
+		|| (ARM64 && !CPU_BIG_ENDIAN)
+	select PARAVIRT
+	select X86_HV_CALLBACK_VECTOR if X86
+	select OF_EARLY_FLATTREE if OF
+	select IRQ_MSI_LIB if X86
+	help
+	  Select this option to run Linux as a Hyper-V client operating
+	  system.
+
+config HYPERV_VTL_MODE
+	bool "Enable Linux to boot in VTL context"
+	depends on (X86_64 && HAVE_STATIC_CALL) || ARM64
+	depends on HYPERV
+	depends on SMP
+	default n
+	help
+	  Virtual Secure Mode (VSM) is a set of hypervisor capabilities and
+	  enlightenments offered to host and guest partitions which enables
+	  the creation and management of new security boundaries within
+	  operating system software.
+
+	  VSM achieves and maintains isolation through Virtual Trust Levels
+	  (VTLs). Virtual Trust Levels are hierarchical, with higher levels
+	  being more privileged than lower levels. VTL0 is the least privileged
+	  level, and currently only other level supported is VTL2.
+
+	  Select this option to build a Linux kernel to run at a VTL other than
+	  the normal VTL0, which currently is only VTL2.  This option
+	  initializes the kernel to run in VTL2, and adds the ability to boot
+	  secondary CPUs directly into 64-bit context as required for VTLs other
+	  than 0.  A kernel built with this option must run at VTL2, and will
+	  not run as a normal guest.
+
+	  If unsure, say N
+
+config HYPERV_TIMER
+	def_bool HYPERV && X86
+
+config HYPERV_UTILS
+	tristate "Microsoft Hyper-V Utilities driver"
+	depends on HYPERV_VMBUS && CONNECTOR && NLS
+	depends on PTP_1588_CLOCK_OPTIONAL
+	help
+	  Select this option to enable the Hyper-V Utilities.
+
+config HYPERV_BALLOON
+	tristate "Microsoft Hyper-V Balloon driver"
+	depends on HYPERV_VMBUS
+	select PAGE_REPORTING
+	help
+	  Select this option to enable Hyper-V Balloon driver.
+
+config HYPERV_VMBUS
+	tristate "Microsoft Hyper-V VMBus driver"
+	depends on HYPERV
+	default HYPERV
+	select SYSFB if EFI && !HYPERV_VTL_MODE
+	help
+	  Select this option to enable Hyper-V Vmbus driver.
+
+config MSHV_ROOT
+	tristate "Microsoft Hyper-V root partition support"
+	depends on HYPERV && (X86_64 || ARM64)
+	depends on !HYPERV_VTL_MODE
+	# The hypervisor interface operates on 4k pages. Enforcing it here
+	# simplifies many assumptions in the root partition code.
+	# e.g. When withdrawing memory, the hypervisor gives back 4k pages in
+	# no particular order, making it impossible to reassemble larger pages
+	depends on PAGE_SIZE_4KB
+	depends on HYPERV_VMBUS if HYPERV_VMBUS
+	select EVENTFD
+	select VIRT_XFER_TO_GUEST_WORK
+	select HMM_MIRROR
+	select MMU_NOTIFIER
+	default n
+	help
+	  Select this option to enable support for booting and running as root
+	  partition on Microsoft Hyper-V.
+
+	  If unsure, say N.
+
+config MSHV_VTL
+	tristate "Microsoft Hyper-V VTL driver"
+	depends on X86_64 && HYPERV_VTL_MODE
+	depends on HYPERV_VMBUS
+	# Mapping VTL0 memory to a userspace process in VTL2 is supported in OpenHCL.
+	# VTL2 for OpenHCL makes use of Huge Pages to improve performance on VMs,
+	# specially with large memory requirements.
+	depends on TRANSPARENT_HUGEPAGE
+	# MTRRs are controlled by VTL0, and are not specific to individual VTLs.
+	# Therefore, do not attempt to access or modify MTRRs here.
+	depends on !MTRR
+	select CPUMASK_OFFSTACK
+	select VIRT_XFER_TO_GUEST_WORK
+	default n
+	help
+	  Select this option to enable Hyper-V VTL driver support.
+	  This driver provides interfaces for Virtual Machine Manager (VMM) running in VTL2
+	  userspace to create VTLs and partitions, setup and manage VTL0 memory and
+	  allow userspace to make direct hypercalls. This also allows to map VTL0's address
+	  space to a usermode process in VTL2 and supports getting new VMBus messages and channel
+	  events in VTL2.
+
+	  If unsure, say N.
+
+endmenu
diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
new file mode 100644
index 000000000..888a748cc
--- /dev/null
+++ b/drivers/hv/Makefile
@@ -0,0 +1,27 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_HYPERV_VMBUS)	+= hv_vmbus.o
+obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
+obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
+obj-$(CONFIG_MSHV_ROOT)		+= mshv_root.o
+obj-$(CONFIG_MSHV_VTL)          += mshv_vtl.o
+
+CFLAGS_hv_trace.o = -I$(src)
+CFLAGS_hv_balloon.o = -I$(src)
+
+hv_vmbus-y := vmbus_drv.o \
+		 hv.o connection.o channel.o \
+		 channel_mgmt.o ring_buffer.o hv_trace.o
+hv_vmbus-$(CONFIG_HYPERV_TESTING)	+= hv_debugfs.o
+hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_utils_transport.o
+mshv_root-y := mshv_root_main.o mshv_synic.o mshv_eventfd.o mshv_irq.o \
+	       mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o
+mshv_root-$(CONFIG_DEBUG_FS) += mshv_debugfs.o
+mshv_root-$(CONFIG_TRACEPOINTS) += mshv_trace.o
+mshv_vtl-y := mshv_vtl_main.o
+
+# Code that must be built-in
+obj-$(CONFIG_HYPERV) += hv_common.o
+obj-$(subst m,y,$(CONFIG_MSHV_ROOT)) += hv_proc.o
+ifneq ($(CONFIG_MSHV_ROOT)$(CONFIG_MSHV_VTL),)
+	obj-y += mshv_common.o
+endif
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
new file mode 100644
index 000000000..7e4cc6f55
--- /dev/null
+++ b/drivers/hv/channel.c
@@ -0,0 +1,1475 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/hyperv.h>
+#include <linux/uio.h>
+#include <linux/interrupt.h>
+#include <linux/set_memory.h>
+#include <linux/vmalloc.h>
+#include <linux/export.h>
+#include <asm/page.h>
+#include <asm/mshyperv.h>
+
+#include "hyperv_vmbus.h"
+
+/*
+ * hv_gpadl_size - Return the real size of a gpadl, the size that Hyper-V uses
+ *
+ * For BUFFER gpadl, Hyper-V uses the exact same size as the guest does.
+ *
+ * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the header
+ * (because of the alignment requirement), however, the hypervisor only
+ * uses the first HV_HYP_PAGE_SIZE as the header, therefore leaving a
+ * (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap. And since there are two rings in a
+ * ringbuffer, the total size for a RING gpadl that Hyper-V uses is the
+ * total size that the guest uses minus twice of the gap size.
+ */
+static inline u32 hv_gpadl_size(enum hv_gpadl_type type, u32 size)
+{
+	switch (type) {
+	case HV_GPADL_BUFFER:
+	case HV_GPADL_BUFFER_DECRYPTED:
+		return size;
+	case HV_GPADL_RING:
+		/* The size of a ringbuffer must be page-aligned */
+		BUG_ON(size % PAGE_SIZE);
+		/*
+		 * Two things to notice here:
+		 * 1) We're processing two ring buffers as a unit
+		 * 2) We're skipping any space larger than HV_HYP_PAGE_SIZE in
+		 * the first guest-size page of each of the two ring buffers.
+		 * So we effectively subtract out two guest-size pages, and add
+		 * back two Hyper-V size pages.
+		 */
+		return size - 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
+	}
+	BUG();
+	return 0;
+}
+
+/*
+ * hv_ring_gpadl_send_hvpgoffset - Calculate the send offset (in unit of
+ *                                 HV_HYP_PAGE) in a ring gpadl based on the
+ *                                 offset in the guest
+ *
+ * @offset: the offset (in bytes) where the send ringbuffer starts in the
+ *               virtual address space of the guest
+ */
+static inline u32 hv_ring_gpadl_send_hvpgoffset(u32 offset)
+{
+
+	/*
+	 * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the
+	 * header (because of the alignment requirement), however, the
+	 * hypervisor only uses the first HV_HYP_PAGE_SIZE as the header,
+	 * therefore leaving a (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap.
+	 *
+	 * And to calculate the effective send offset in gpadl, we need to
+	 * substract this gap.
+	 */
+	return (offset - (PAGE_SIZE - HV_HYP_PAGE_SIZE)) >> HV_HYP_PAGE_SHIFT;
+}
+
+/*
+ * hv_gpadl_hvpfn - Return the Hyper-V page PFN of the @i th Hyper-V page in
+ *                  the gpadl
+ *
+ * @type: the type of the gpadl
+ * @kbuffer: the pointer to the gpadl in the guest
+ * @size: the total size (in bytes) of the gpadl
+ * @send_offset: the offset (in bytes) where the send ringbuffer starts in the
+ *               virtual address space of the guest
+ * @i: the index
+ */
+static inline u64 hv_gpadl_hvpfn(enum hv_gpadl_type type, void *kbuffer,
+				 u32 size, u32 send_offset, int i)
+{
+	int send_idx = hv_ring_gpadl_send_hvpgoffset(send_offset);
+	unsigned long delta = 0UL;
+
+	switch (type) {
+	case HV_GPADL_BUFFER:
+	case HV_GPADL_BUFFER_DECRYPTED:
+		break;
+	case HV_GPADL_RING:
+		if (i == 0)
+			delta = 0;
+		else if (i <= send_idx)
+			delta = PAGE_SIZE - HV_HYP_PAGE_SIZE;
+		else
+			delta = 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
+		break;
+	default:
+		BUG();
+		break;
+	}
+
+	return virt_to_hvpfn(kbuffer + delta + (HV_HYP_PAGE_SIZE * i));
+}
+
+/*
+ * vmbus_setevent- Trigger an event notification on the specified
+ * channel.
+ */
+void vmbus_setevent(struct vmbus_channel *channel)
+{
+	struct hv_monitor_page *monitorpage;
+
+	trace_vmbus_setevent(channel);
+
+	/*
+	 * For channels marked as in "low latency" mode
+	 * bypass the monitor page mechanism.
+	 */
+	if (channel->offermsg.monitor_allocated && !channel->low_latency) {
+		vmbus_send_interrupt(channel->offermsg.child_relid);
+
+		/* Get the child to parent monitor page */
+		monitorpage = vmbus_connection.monitor_pages[1];
+
+		sync_set_bit(channel->monitor_bit,
+			(unsigned long *)&monitorpage->trigger_group
+					[channel->monitor_grp].pending);
+
+	} else {
+		vmbus_set_event(channel);
+	}
+}
+EXPORT_SYMBOL_GPL(vmbus_setevent);
+
+/* vmbus_free_ring - drop mapping of ring buffer */
+void vmbus_free_ring(struct vmbus_channel *channel)
+{
+	hv_ringbuffer_cleanup(&channel->outbound);
+	hv_ringbuffer_cleanup(&channel->inbound);
+
+	if (channel->ringbuffer_page) {
+		/* In a CoCo VM leak the memory if it didn't get re-encrypted */
+		if (!channel->ringbuffer_gpadlhandle.decrypted)
+			__free_pages(channel->ringbuffer_page,
+			     get_order(channel->ringbuffer_pagecount
+				       << PAGE_SHIFT));
+		channel->ringbuffer_page = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(vmbus_free_ring);
+
+/* vmbus_alloc_ring - allocate and map pages for ring buffer */
+int vmbus_alloc_ring(struct vmbus_channel *newchannel,
+		     u32 send_size, u32 recv_size)
+{
+	struct page *page;
+	int order;
+
+	if (send_size % PAGE_SIZE || recv_size % PAGE_SIZE)
+		return -EINVAL;
+
+	/* Allocate the ring buffer */
+	order = get_order(send_size + recv_size);
+	page = alloc_pages_node(cpu_to_node(newchannel->target_cpu),
+				GFP_KERNEL|__GFP_ZERO, order);
+
+	if (!page)
+		page = alloc_pages(GFP_KERNEL|__GFP_ZERO, order);
+
+	if (!page)
+		return -ENOMEM;
+
+	newchannel->ringbuffer_page = page;
+	newchannel->ringbuffer_pagecount = (send_size + recv_size) >> PAGE_SHIFT;
+	newchannel->ringbuffer_send_offset = send_size >> PAGE_SHIFT;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vmbus_alloc_ring);
+
+/* Used for Hyper-V Socket: a guest client's connect() to the host */
+int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
+				  const guid_t *shv_host_servie_id)
+{
+	struct vmbus_channel_tl_connect_request conn_msg;
+	int ret;
+
+	memset(&conn_msg, 0, sizeof(conn_msg));
+	conn_msg.header.msgtype = CHANNELMSG_TL_CONNECT_REQUEST;
+	conn_msg.guest_endpoint_id = *shv_guest_servie_id;
+	conn_msg.host_service_id = *shv_host_servie_id;
+
+	ret = vmbus_post_msg(&conn_msg, sizeof(conn_msg), true);
+
+	trace_vmbus_send_tl_connect_request(&conn_msg, ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_send_tl_connect_request);
+
+static int send_modifychannel_without_ack(struct vmbus_channel *channel, u32 target_vp)
+{
+	struct vmbus_channel_modifychannel msg;
+	int ret;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.header.msgtype = CHANNELMSG_MODIFYCHANNEL;
+	msg.child_relid = channel->offermsg.child_relid;
+	msg.target_vp = target_vp;
+
+	ret = vmbus_post_msg(&msg, sizeof(msg), true);
+	trace_vmbus_send_modifychannel(&msg, ret);
+
+	return ret;
+}
+
+static int send_modifychannel_with_ack(struct vmbus_channel *channel, u32 target_vp)
+{
+	struct vmbus_channel_modifychannel *msg;
+	struct vmbus_channel_msginfo *info;
+	unsigned long flags;
+	int ret;
+
+	info = kzalloc(sizeof(struct vmbus_channel_msginfo) +
+				sizeof(struct vmbus_channel_modifychannel),
+		       GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	init_completion(&info->waitevent);
+	info->waiting_channel = channel;
+
+	msg = (struct vmbus_channel_modifychannel *)info->msg;
+	msg->header.msgtype = CHANNELMSG_MODIFYCHANNEL;
+	msg->child_relid = channel->offermsg.child_relid;
+	msg->target_vp = target_vp;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&info->msglistentry, &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	ret = vmbus_post_msg(msg, sizeof(*msg), true);
+	trace_vmbus_send_modifychannel(msg, ret);
+	if (ret != 0) {
+		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+		list_del(&info->msglistentry);
+		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+		goto free_info;
+	}
+
+	/*
+	 * Release channel_mutex; otherwise, vmbus_onoffer_rescind() could block on
+	 * the mutex and be unable to signal the completion.
+	 *
+	 * See the caller target_cpu_store() for information about the usage of the
+	 * mutex.
+	 */
+	mutex_unlock(&vmbus_connection.channel_mutex);
+	wait_for_completion(&info->waitevent);
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (info->response.modify_response.status)
+		ret = -EAGAIN;
+
+free_info:
+	kfree(info);
+	return ret;
+}
+
+/*
+ * Set/change the vCPU (@target_vp) the channel (@child_relid) will interrupt.
+ *
+ * CHANNELMSG_MODIFYCHANNEL messages are aynchronous.  When VMbus version 5.3
+ * or later is negotiated, Hyper-V always sends an ACK in response to such a
+ * message.  For VMbus version 5.2 and earlier, it never sends an ACK.  With-
+ * out an ACK, we can not know when the host will stop interrupting the "old"
+ * vCPU and start interrupting the "new" vCPU for the given channel.
+ *
+ * The CHANNELMSG_MODIFYCHANNEL message type is supported since VMBus version
+ * VERSION_WIN10_V4_1.
+ */
+int vmbus_send_modifychannel(struct vmbus_channel *channel, u32 target_vp)
+{
+	if (vmbus_proto_version >= VERSION_WIN10_V5_3)
+		return send_modifychannel_with_ack(channel, target_vp);
+	return send_modifychannel_without_ack(channel, target_vp);
+}
+EXPORT_SYMBOL_GPL(vmbus_send_modifychannel);
+
+/*
+ * create_gpadl_header - Creates a gpadl for the specified buffer
+ */
+static int create_gpadl_header(enum hv_gpadl_type type, void *kbuffer,
+			       u32 size, u32 send_offset,
+			       struct vmbus_channel_msginfo **msginfo)
+{
+	int i;
+	int pagecount;
+	struct vmbus_channel_gpadl_header *gpadl_header;
+	struct vmbus_channel_gpadl_body *gpadl_body;
+	struct vmbus_channel_msginfo *msgheader;
+	struct vmbus_channel_msginfo *msgbody = NULL;
+	u32 msgsize;
+
+	int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
+
+	pagecount = hv_gpadl_size(type, size) >> HV_HYP_PAGE_SHIFT;
+
+	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+		  sizeof(struct vmbus_channel_gpadl_header) -
+		  sizeof(struct gpa_range);
+	pfncount = umin(pagecount, pfnsize / sizeof(u64));
+
+	msgsize = sizeof(struct vmbus_channel_msginfo) +
+		  sizeof(struct vmbus_channel_gpadl_header) +
+		  sizeof(struct gpa_range) + pfncount * sizeof(u64);
+	msgheader =  kzalloc(msgsize, GFP_KERNEL);
+	if (!msgheader)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&msgheader->submsglist);
+	msgheader->msgsize = msgsize;
+
+	gpadl_header = (struct vmbus_channel_gpadl_header *)
+		msgheader->msg;
+	gpadl_header->rangecount = 1;
+	gpadl_header->range_buflen = sizeof(struct gpa_range) +
+				 pagecount * sizeof(u64);
+	gpadl_header->range[0].byte_offset = 0;
+	gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
+	for (i = 0; i < pfncount; i++)
+		gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
+			type, kbuffer, size, send_offset, i);
+	*msginfo = msgheader;
+
+	pfnsum = pfncount;
+	pfnleft = pagecount - pfncount;
+
+	/* how many pfns can we fit in a body message */
+	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+		  sizeof(struct vmbus_channel_gpadl_body);
+	pfncount = pfnsize / sizeof(u64);
+
+	/*
+	 * If pfnleft is zero, everything fits in the header and no body
+	 * messages are needed
+	 */
+	while (pfnleft) {
+		pfncurr = umin(pfncount, pfnleft);
+		msgsize = sizeof(struct vmbus_channel_msginfo) +
+			  sizeof(struct vmbus_channel_gpadl_body) +
+			  pfncurr * sizeof(u64);
+		msgbody = kzalloc(msgsize, GFP_KERNEL);
+
+		if (!msgbody) {
+			struct vmbus_channel_msginfo *pos = NULL;
+			struct vmbus_channel_msginfo *tmp = NULL;
+			/*
+			 * Free up all the allocated messages.
+			 */
+			list_for_each_entry_safe(pos, tmp,
+				&msgheader->submsglist,
+				msglistentry) {
+
+				list_del(&pos->msglistentry);
+				kfree(pos);
+			}
+			kfree(msgheader);
+			return -ENOMEM;
+		}
+
+		msgbody->msgsize = msgsize;
+		gpadl_body = (struct vmbus_channel_gpadl_body *)msgbody->msg;
+
+		/*
+		 * Gpadl is u32 and we are using a pointer which could
+		 * be 64-bit
+		 * This is governed by the guest/host protocol and
+		 * so the hypervisor guarantees that this is ok.
+		 */
+		for (i = 0; i < pfncurr; i++)
+			gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
+				kbuffer, size, send_offset, pfnsum + i);
+
+		/* add to msg header */
+		list_add_tail(&msgbody->msglistentry, &msgheader->submsglist);
+		pfnsum += pfncurr;
+		pfnleft -= pfncurr;
+	}
+
+	return 0;
+}
+
+static void vmbus_free_channel_msginfo(struct vmbus_channel_msginfo *msginfo)
+{
+	struct vmbus_channel_msginfo *submsginfo, *tmp;
+
+	if (!msginfo)
+		return;
+
+	list_for_each_entry_safe(submsginfo, tmp, &msginfo->submsglist,
+				 msglistentry) {
+		kfree(submsginfo);
+	}
+
+	kfree(msginfo);
+}
+
+/*
+ * __vmbus_establish_gpadl - Establish a GPADL for a buffer or ringbuffer
+ *
+ * @channel: a channel
+ * @type: the type of the corresponding GPADL, only meaningful for the guest.
+ * @kbuffer: from kmalloc or vmalloc
+ * @size: page-size multiple
+ * @send_offset: the offset (in bytes) where the send ring buffer starts,
+ *              should be 0 for BUFFER type gpadl
+ * @gpadl_handle: some funky thing
+ */
+static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
+				   enum hv_gpadl_type type, void *kbuffer,
+				   u32 size, u32 send_offset,
+				   struct vmbus_gpadl *gpadl)
+{
+	struct vmbus_channel_gpadl_header *gpadlmsg;
+	struct vmbus_channel_gpadl_body *gpadl_body;
+	struct vmbus_channel_msginfo *msginfo = NULL;
+	struct vmbus_channel_msginfo *submsginfo;
+	struct list_head *curr;
+	u32 next_gpadl_handle;
+	unsigned long flags;
+	int ret = 0;
+
+	next_gpadl_handle =
+		(atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
+
+	ret = create_gpadl_header(type, kbuffer, size, send_offset, &msginfo);
+	if (ret) {
+		gpadl->decrypted = false;
+		return ret;
+	}
+
+	gpadl->decrypted = !((channel->co_external_memory && type == HV_GPADL_BUFFER) ||
+		(channel->co_ring_buffer && type == HV_GPADL_RING) ||
+		(type == HV_GPADL_BUFFER_DECRYPTED));
+	if (gpadl->decrypted) {
+		/*
+		 * The "decrypted" flag being true assumes that set_memory_decrypted() succeeds.
+		 * But if it fails, the encryption state of the memory is unknown. In that case,
+		 * leave "decrypted" as true to ensure the memory is leaked instead of going back
+		 * on the free list.
+		 */
+		ret = set_memory_decrypted((unsigned long)kbuffer,
+					PFN_UP(size));
+		if (ret) {
+			dev_warn(&channel->device_obj->device,
+				"Failed to set host visibility for new GPADL %d.\n",
+				ret);
+			vmbus_free_channel_msginfo(msginfo);
+			return ret;
+		}
+	}
+
+	init_completion(&msginfo->waitevent);
+	msginfo->waiting_channel = channel;
+
+	gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo->msg;
+	gpadlmsg->header.msgtype = CHANNELMSG_GPADL_HEADER;
+	gpadlmsg->child_relid = channel->offermsg.child_relid;
+	gpadlmsg->gpadl = next_gpadl_handle;
+
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&msginfo->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (channel->rescind) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
+			     sizeof(*msginfo), true);
+
+	trace_vmbus_establish_gpadl_header(gpadlmsg, ret);
+
+	if (ret != 0)
+		goto cleanup;
+
+	list_for_each(curr, &msginfo->submsglist) {
+		submsginfo = (struct vmbus_channel_msginfo *)curr;
+		gpadl_body =
+			(struct vmbus_channel_gpadl_body *)submsginfo->msg;
+
+		gpadl_body->header.msgtype =
+			CHANNELMSG_GPADL_BODY;
+		gpadl_body->gpadl = next_gpadl_handle;
+
+		ret = vmbus_post_msg(gpadl_body,
+				     submsginfo->msgsize - sizeof(*submsginfo),
+				     true);
+
+		trace_vmbus_establish_gpadl_body(gpadl_body, ret);
+
+		if (ret != 0)
+			goto cleanup;
+
+	}
+	wait_for_completion(&msginfo->waitevent);
+
+	if (msginfo->response.gpadl_created.creation_status != 0) {
+		pr_err("Failed to establish GPADL: err = 0x%x\n",
+		       msginfo->response.gpadl_created.creation_status);
+
+		ret = -EDQUOT;
+		goto cleanup;
+	}
+
+	if (channel->rescind) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	/* At this point, we received the gpadl created msg */
+	gpadl->gpadl_handle = gpadlmsg->gpadl;
+	gpadl->buffer = kbuffer;
+	gpadl->size = size;
+
+
+cleanup:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&msginfo->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	vmbus_free_channel_msginfo(msginfo);
+
+	if (ret) {
+		/*
+		 * If set_memory_encrypted() fails, the decrypted flag is
+		 * left as true so the memory is leaked instead of being
+		 * put back on the free list.
+		 */
+		if (gpadl->decrypted) {
+			if (!set_memory_encrypted((unsigned long)kbuffer, PFN_UP(size)))
+				gpadl->decrypted = false;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * vmbus_establish_gpadl - Establish a GPADL for the specified buffer
+ *
+ * @channel: a channel
+ * @kbuffer: from kmalloc or vmalloc
+ * @size: page-size multiple
+ * @gpadl: output gpadl
+ */
+int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
+			  u32 size, struct vmbus_gpadl *gpadl)
+{
+	return __vmbus_establish_gpadl(channel, HV_GPADL_BUFFER, kbuffer, size,
+				       0U, gpadl);
+}
+EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
+
+/*
+ * vmbus_establish_gpadl_caller_decrypted - Establish a GPADL for a buffer
+ * that has already been decrypted by the caller.
+ *
+ * @channel: a channel
+ * @kbuffer: from kmalloc or vmalloc; must already be decrypted by the caller
+ * @size: page-size multiple
+ * @gpadl: output gpadl
+ *
+ * The caller is responsible for re-encrypting the buffer before freeing it.
+ */
+int vmbus_establish_gpadl_caller_decrypted(struct vmbus_channel *channel,
+					   void *kbuffer, u32 size,
+					   struct vmbus_gpadl *gpadl)
+{
+	return __vmbus_establish_gpadl(channel, HV_GPADL_BUFFER_DECRYPTED,
+				       kbuffer, size, 0U, gpadl);
+}
+EXPORT_SYMBOL_GPL(vmbus_establish_gpadl_caller_decrypted);
+
+/**
+ * vmbus_free_buffer - release a buffer allocated by vmbus_alloc_buffer().
+ *
+ * @addr: buffer address, or NULL if none was allocated (e.g. cleanup from a
+ *        failed allocation)
+ * @chunks: chunks array from vmbus_alloc_buffer(), or NULL
+ * @chunk_cnt: number of entries in @chunks
+ *
+ * When @chunks is NULL the buffer is a plain vzalloc() allocation.
+ *
+ * Otherwise tear down the vmap, and for each chunk re-encrypt and free
+ * the underlying pages. Any chunk that cannot be re-encrypted is leaked.
+ */
+void vmbus_free_buffer(void *addr, struct page **chunks, u32 chunk_cnt)
+{
+	u32 i;
+
+	if (!chunks) {
+		vfree(addr);
+		return;
+	}
+
+	vunmap(addr);
+
+	for (i = 0; i < chunk_cnt; i++) {
+		unsigned long vaddr =
+			(unsigned long)page_address(chunks[i]);
+		unsigned int order = folio_order(page_folio(chunks[i]));
+
+		if (set_memory_encrypted(vaddr, 1U << order))
+			continue;
+		__free_pages(chunks[i], order);
+	}
+
+	kvfree(chunks);
+}
+EXPORT_SYMBOL_GPL(vmbus_free_buffer);
+
+/**
+ * vmbus_alloc_buffer - allocate a host-visible, virtually-contiguous buffer.
+ *
+ * @channel: the channel the buffer will be attached to
+ * @size: requested buffer size in bytes (will be rounded up to PAGE_SIZE)
+ * @chunks_out: on success, set to the array of underlying chunks, or NULL when
+ *              the buffer was allocated with vzalloc()
+ * @chunk_cnt_out: on success, set to the number of chunks
+ *
+ * Buffers not requiring decryption are allocated with vzalloc().
+ *
+ * Buffers requiring decryption are allocated as a series of
+ * physically-contiguous chunks, starting at MAX_PAGE_ORDER and falling back to
+ * smaller orders on allocation failure. Each chunk is transitioned to
+ * host-visible via set_memory_decrypted() on its direct-map address, then all
+ * chunks are combined into a virtually-contiguous range via vmap().
+ *
+ * Return: the buffer's virtual address, or NULL on failure.
+ */
+void *vmbus_alloc_buffer(struct vmbus_channel *channel,
+			 u32 size,
+			 struct page ***chunks_out,
+			 u32 *chunk_cnt_out)
+{
+	unsigned long nr_pages = PFN_UP(size);
+	unsigned long remaining = nr_pages;
+	unsigned long page_idx = 0;
+	struct page **chunks = NULL;
+	struct page **pages = NULL;
+	int order = MAX_PAGE_ORDER;
+	u32 chunk_cnt = 0;
+	void *addr;
+	u32 i;
+	int ret;
+
+	*chunks_out = NULL;
+	*chunk_cnt_out = 0;
+
+	if (!nr_pages)
+		return NULL;
+
+	/* If the buffer does not need to be decrypted, just use vzalloc() */
+	if (!hv_is_isolation_supported() || channel->co_external_memory)
+		return vzalloc(nr_pages << PAGE_SHIFT);
+
+	/* Worst case: every chunk is a single page. */
+	chunks = kvmalloc_objs(*chunks, nr_pages, GFP_KERNEL | __GFP_ZERO);
+	if (!chunks)
+		goto err;
+
+	pages = kvmalloc_objs(*pages, nr_pages);
+	if (!pages)
+		goto err;
+
+	while (remaining) {
+		struct page *page;
+		gfp_t gfp;
+
+		order = min(order, ilog2(remaining));
+
+		/*
+		 * Use __GFP_NORETRY | __GFP_NOWARN to avoid OOM-killing,
+		 * but try harder at order 0 since that is the final
+		 * fallback.
+		 * __GFP_COMP stores order information in the page folio.
+		 */
+		gfp = GFP_KERNEL | __GFP_ZERO;
+		if (order)
+			gfp |= __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN;
+
+		page = alloc_pages_node(cpu_to_node(channel->target_cpu),
+					gfp, order);
+		if (!page) {
+			if (!order--)
+				goto err;
+			continue;
+		}
+
+		ret = set_memory_decrypted((unsigned long)page_address(page),
+					   1U << order);
+		if (ret) {
+			/*
+			 * set_memory_decrypted() failed; the page state is
+			 * unknown so it must be leaked rather than freed.
+			 */
+			goto err;
+		}
+
+		chunks[chunk_cnt++] = page;
+
+		for (i = 0; i < (1U << order); i++)
+			pages[page_idx++] = page + i;
+
+		remaining -= 1U << order;
+	}
+
+	addr = vmap(pages, nr_pages, VM_MAP, pgprot_decrypted(PAGE_KERNEL));
+	if (!addr)
+		goto err;
+
+	memset(addr, 0, nr_pages << PAGE_SHIFT);
+
+	kvfree(pages);
+	*chunks_out = chunks;
+	*chunk_cnt_out = chunk_cnt;
+	return addr;
+
+err:
+	kvfree(pages);
+	vmbus_free_buffer(NULL, chunks, chunk_cnt);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(vmbus_alloc_buffer);
+
+/**
+ * request_arr_init - Allocates memory for the requestor array. Each slot
+ * keeps track of the next available slot in the array. Initially, each
+ * slot points to the next one (as in a Linked List). The last slot
+ * does not point to anything, so its value is U64_MAX by default.
+ * @size: The size of the array
+ */
+static u64 *request_arr_init(u32 size)
+{
+	int i;
+	u64 *req_arr;
+
+	req_arr = kcalloc(size, sizeof(u64), GFP_KERNEL);
+	if (!req_arr)
+		return NULL;
+
+	for (i = 0; i < size - 1; i++)
+		req_arr[i] = i + 1;
+
+	/* Last slot (no more available slots) */
+	req_arr[i] = U64_MAX;
+
+	return req_arr;
+}
+
+/*
+ * vmbus_alloc_requestor - Initializes @rqstor's fields.
+ * Index 0 is the first free slot
+ * @size: Size of the requestor array
+ */
+static int vmbus_alloc_requestor(struct vmbus_requestor *rqstor, u32 size)
+{
+	u64 *rqst_arr;
+	unsigned long *bitmap;
+
+	rqst_arr = request_arr_init(size);
+	if (!rqst_arr)
+		return -ENOMEM;
+
+	bitmap = bitmap_zalloc(size, GFP_KERNEL);
+	if (!bitmap) {
+		kfree(rqst_arr);
+		return -ENOMEM;
+	}
+
+	rqstor->req_arr = rqst_arr;
+	rqstor->req_bitmap = bitmap;
+	rqstor->size = size;
+	rqstor->next_request_id = 0;
+	spin_lock_init(&rqstor->req_lock);
+
+	return 0;
+}
+
+/*
+ * vmbus_free_requestor - Frees memory allocated for @rqstor
+ * @rqstor: Pointer to the requestor struct
+ */
+static void vmbus_free_requestor(struct vmbus_requestor *rqstor)
+{
+	kfree(rqstor->req_arr);
+	bitmap_free(rqstor->req_bitmap);
+}
+
+static int __vmbus_open(struct vmbus_channel *newchannel,
+		       void *userdata, u32 userdatalen,
+		       void (*onchannelcallback)(void *context), void *context)
+{
+	struct vmbus_channel_open_channel *open_msg;
+	struct vmbus_channel_msginfo *open_info = NULL;
+	struct page *page = newchannel->ringbuffer_page;
+	u32 send_pages, recv_pages;
+	unsigned long flags;
+	int err;
+
+	if (userdatalen > MAX_USER_DEFINED_BYTES)
+		return -EINVAL;
+
+	send_pages = newchannel->ringbuffer_send_offset;
+	recv_pages = newchannel->ringbuffer_pagecount - send_pages;
+
+	if (newchannel->state != CHANNEL_OPEN_STATE)
+		return -EINVAL;
+
+	/* Create and init requestor */
+	if (newchannel->rqstor_size) {
+		if (vmbus_alloc_requestor(&newchannel->requestor, newchannel->rqstor_size))
+			return -ENOMEM;
+	}
+
+	newchannel->state = CHANNEL_OPENING_STATE;
+	newchannel->onchannel_callback = onchannelcallback;
+	newchannel->channel_callback_context = context;
+
+	if (!newchannel->max_pkt_size)
+		newchannel->max_pkt_size = VMBUS_DEFAULT_MAX_PKT_SIZE;
+
+	/* Establish the gpadl for the ring buffer */
+	newchannel->ringbuffer_gpadlhandle.gpadl_handle = 0;
+
+	err = __vmbus_establish_gpadl(newchannel, HV_GPADL_RING,
+				      page_address(newchannel->ringbuffer_page),
+				      (send_pages + recv_pages) << PAGE_SHIFT,
+				      newchannel->ringbuffer_send_offset << PAGE_SHIFT,
+				      &newchannel->ringbuffer_gpadlhandle);
+	if (err)
+		goto error_clean_ring;
+
+	err = hv_ringbuffer_init(&newchannel->outbound,
+				 page, send_pages, 0, newchannel->co_ring_buffer);
+	if (err)
+		goto error_free_gpadl;
+
+	err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
+				 recv_pages, newchannel->max_pkt_size,
+				 newchannel->co_ring_buffer);
+	if (err)
+		goto error_free_gpadl;
+
+	/* Create and init the channel open message */
+	open_info = kzalloc(sizeof(*open_info) +
+			   sizeof(struct vmbus_channel_open_channel),
+			   GFP_KERNEL);
+	if (!open_info) {
+		err = -ENOMEM;
+		goto error_free_gpadl;
+	}
+
+	init_completion(&open_info->waitevent);
+	open_info->waiting_channel = newchannel;
+
+	open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
+	open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
+	open_msg->openid = newchannel->offermsg.child_relid;
+	open_msg->child_relid = newchannel->offermsg.child_relid;
+	open_msg->ringbuffer_gpadlhandle
+		= newchannel->ringbuffer_gpadlhandle.gpadl_handle;
+	/*
+	 * The unit of ->downstream_ringbuffer_pageoffset is HV_HYP_PAGE and
+	 * the unit of ->ringbuffer_send_offset (i.e. send_pages) is PAGE, so
+	 * here we calculate it into HV_HYP_PAGE.
+	 */
+	open_msg->downstream_ringbuffer_pageoffset =
+		hv_ring_gpadl_send_hvpgoffset(send_pages << PAGE_SHIFT);
+	open_msg->target_vp = hv_cpu_number_to_vp_number(newchannel->target_cpu);
+
+	if (userdatalen)
+		memcpy(open_msg->userdata, userdata, userdatalen);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&open_info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (newchannel->rescind) {
+		err = -ENODEV;
+		goto error_clean_msglist;
+	}
+
+	err = vmbus_post_msg(open_msg,
+			     sizeof(struct vmbus_channel_open_channel), true);
+
+	trace_vmbus_open(open_msg, err);
+
+	if (err != 0)
+		goto error_clean_msglist;
+
+	wait_for_completion(&open_info->waitevent);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (newchannel->rescind) {
+		err = -ENODEV;
+		goto error_free_info;
+	}
+
+	if (open_info->response.open_result.status) {
+		err = -EAGAIN;
+		goto error_free_info;
+	}
+
+	newchannel->state = CHANNEL_OPENED_STATE;
+	kfree(open_info);
+	return 0;
+
+error_clean_msglist:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+error_free_info:
+	kfree(open_info);
+error_free_gpadl:
+	vmbus_teardown_gpadl(newchannel, &newchannel->ringbuffer_gpadlhandle);
+error_clean_ring:
+	hv_ringbuffer_cleanup(&newchannel->outbound);
+	hv_ringbuffer_cleanup(&newchannel->inbound);
+	vmbus_free_requestor(&newchannel->requestor);
+	newchannel->state = CHANNEL_OPEN_STATE;
+	return err;
+}
+
+/*
+ * vmbus_connect_ring - Open the channel but reuse ring buffer
+ */
+int vmbus_connect_ring(struct vmbus_channel *newchannel,
+		       void (*onchannelcallback)(void *context), void *context)
+{
+	return  __vmbus_open(newchannel, NULL, 0, onchannelcallback, context);
+}
+EXPORT_SYMBOL_GPL(vmbus_connect_ring);
+
+/*
+ * vmbus_open - Open the specified channel.
+ */
+int vmbus_open(struct vmbus_channel *newchannel,
+	       u32 send_ringbuffer_size, u32 recv_ringbuffer_size,
+	       void *userdata, u32 userdatalen,
+	       void (*onchannelcallback)(void *context), void *context)
+{
+	int err;
+
+	err = vmbus_alloc_ring(newchannel, send_ringbuffer_size,
+			       recv_ringbuffer_size);
+	if (err)
+		return err;
+
+	err = __vmbus_open(newchannel, userdata, userdatalen,
+			   onchannelcallback, context);
+	if (err)
+		vmbus_free_ring(newchannel);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(vmbus_open);
+
+/*
+ * vmbus_teardown_gpadl -Teardown the specified GPADL handle
+ */
+int vmbus_teardown_gpadl(struct vmbus_channel *channel, struct vmbus_gpadl *gpadl)
+{
+	struct vmbus_channel_gpadl_teardown *msg;
+	struct vmbus_channel_msginfo *info;
+	unsigned long flags;
+	int ret;
+
+	info = kzalloc(sizeof(*info) +
+		       sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	init_completion(&info->waitevent);
+	info->waiting_channel = channel;
+
+	msg = (struct vmbus_channel_gpadl_teardown *)info->msg;
+
+	msg->header.msgtype = CHANNELMSG_GPADL_TEARDOWN;
+	msg->child_relid = channel->offermsg.child_relid;
+	msg->gpadl = gpadl->gpadl_handle;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (channel->rescind)
+		goto post_msg_err;
+
+	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_gpadl_teardown),
+			     true);
+
+	trace_vmbus_teardown_gpadl(msg, ret);
+
+	if (ret)
+		goto post_msg_err;
+
+	wait_for_completion(&info->waitevent);
+
+	gpadl->gpadl_handle = 0;
+
+post_msg_err:
+	/*
+	 * If the channel has been rescinded;
+	 * we will be awakened by the rescind
+	 * handler; set the error code to zero so we don't leak memory.
+	 */
+	if (channel->rescind)
+		ret = 0;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	kfree(info);
+
+	if (gpadl->decrypted)
+		ret = set_memory_encrypted((unsigned long)gpadl->buffer,
+					PFN_UP(gpadl->size));
+	else
+		ret = 0;
+	if (ret)
+		pr_warn("Fail to set mem host visibility in GPADL teardown %d.\n", ret);
+
+	gpadl->decrypted = ret;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
+
+void vmbus_reset_channel_cb(struct vmbus_channel *channel)
+{
+	unsigned long flags;
+
+	/*
+	 * vmbus_on_event(), running in the per-channel tasklet, can race
+	 * with vmbus_close_internal() in the case of SMP guest, e.g., when
+	 * the former is accessing channel->inbound.ring_buffer, the latter
+	 * could be freeing the ring_buffer pages, so here we must stop it
+	 * first.
+	 *
+	 * vmbus_chan_sched() might call the netvsc driver callback function
+	 * that ends up scheduling NAPI work that accesses the ring buffer.
+	 * At this point, we have to ensure that any such work is completed
+	 * and that the channel ring buffer is no longer being accessed, cf.
+	 * the calls to napi_disable() in netvsc_device_remove().
+	 */
+	tasklet_disable(&channel->callback_event);
+
+	/* See the inline comments in vmbus_chan_sched(). */
+	spin_lock_irqsave(&channel->sched_lock, flags);
+	channel->onchannel_callback = NULL;
+	spin_unlock_irqrestore(&channel->sched_lock, flags);
+
+	channel->sc_creation_callback = NULL;
+
+	/* Re-enable tasklet for use on re-open */
+	tasklet_enable(&channel->callback_event);
+}
+
+static int vmbus_close_internal(struct vmbus_channel *channel)
+{
+	struct vmbus_channel_close_channel *msg;
+	int ret;
+
+	vmbus_reset_channel_cb(channel);
+
+	/*
+	 * In case a device driver's probe() fails (e.g.,
+	 * util_probe() -> vmbus_open() returns -ENOMEM) and the device is
+	 * rescinded later (e.g., we dynamically disable an Integrated Service
+	 * in Hyper-V Manager), the driver's remove() invokes vmbus_close():
+	 * here we should skip most of the below cleanup work.
+	 */
+	if (channel->state != CHANNEL_OPENED_STATE)
+		return -EINVAL;
+
+	channel->state = CHANNEL_OPEN_STATE;
+
+	/* Send a closing message */
+
+	msg = &channel->close_msg;
+
+	msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
+	msg->child_relid = channel->offermsg.child_relid;
+
+	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_close_channel),
+			     true);
+
+	trace_vmbus_close_internal(msg, ret);
+
+	if (ret) {
+		pr_err("Close failed: close post msg return is %d\n", ret);
+		/*
+		 * If we failed to post the close msg,
+		 * it is perhaps better to leak memory.
+		 */
+	}
+
+	/* Tear down the gpadl for the channel's ring buffer */
+	else if (channel->ringbuffer_gpadlhandle.gpadl_handle) {
+		ret = vmbus_teardown_gpadl(channel, &channel->ringbuffer_gpadlhandle);
+		if (ret) {
+			pr_err("Close failed: teardown gpadl return %d\n", ret);
+			/*
+			 * If we failed to teardown gpadl,
+			 * it is perhaps better to leak memory.
+			 */
+		}
+	}
+
+	if (!ret)
+		vmbus_free_requestor(&channel->requestor);
+
+	return ret;
+}
+
+/* disconnect ring - close all channels */
+int vmbus_disconnect_ring(struct vmbus_channel *channel)
+{
+	struct vmbus_channel *cur_channel, *tmp;
+	int ret;
+
+	if (channel->primary_channel != NULL)
+		return -EINVAL;
+
+	list_for_each_entry_safe(cur_channel, tmp, &channel->sc_list, sc_list) {
+		if (cur_channel->rescind)
+			wait_for_completion(&cur_channel->rescind_event);
+
+		mutex_lock(&vmbus_connection.channel_mutex);
+		if (vmbus_close_internal(cur_channel) == 0) {
+			vmbus_free_ring(cur_channel);
+
+			if (cur_channel->rescind)
+				hv_process_channel_removal(cur_channel);
+		}
+		mutex_unlock(&vmbus_connection.channel_mutex);
+	}
+
+	/*
+	 * Now close the primary.
+	 */
+	mutex_lock(&vmbus_connection.channel_mutex);
+	ret = vmbus_close_internal(channel);
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_disconnect_ring);
+
+/*
+ * vmbus_close - Close the specified channel
+ */
+void vmbus_close(struct vmbus_channel *channel)
+{
+	if (vmbus_disconnect_ring(channel) == 0)
+		vmbus_free_ring(channel);
+}
+EXPORT_SYMBOL_GPL(vmbus_close);
+
+/**
+ * vmbus_sendpacket_getid() - Send the specified buffer on the given channel
+ * @channel: Pointer to vmbus_channel structure
+ * @buffer: Pointer to the buffer you want to send the data from.
+ * @bufferlen: Maximum size of what the buffer holds.
+ * @requestid: Identifier of the request
+ * @trans_id: Identifier of the transaction associated to this request, if
+ *            the send is successful; undefined, otherwise.
+ * @type: Type of packet that is being sent e.g. negotiate, time
+ *	  packet etc.
+ * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
+ *
+ * Sends data in @buffer directly to Hyper-V via the vmbus.
+ * This will send the data unparsed to Hyper-V.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+int vmbus_sendpacket_getid(struct vmbus_channel *channel, void *buffer,
+			   u32 bufferlen, u64 requestid, u64 *trans_id,
+			   enum vmbus_packet_type type, u32 flags)
+{
+	struct vmpacket_descriptor desc;
+	u32 packetlen = sizeof(struct vmpacket_descriptor) + bufferlen;
+	u32 packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+	int num_vecs = ((bufferlen != 0) ? 3 : 1);
+
+
+	/* Setup the descriptor */
+	desc.type = type; /* VmbusPacketTypeDataInBand; */
+	desc.flags = flags; /* VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; */
+	/* in 8-bytes granularity */
+	desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
+	desc.len8 = (u16)(packetlen_aligned >> 3);
+	desc.trans_id = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
+
+	bufferlist[0].iov_base = &desc;
+	bufferlist[0].iov_len = sizeof(struct vmpacket_descriptor);
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid, trans_id);
+}
+EXPORT_SYMBOL(vmbus_sendpacket_getid);
+
+/**
+ * vmbus_sendpacket() - Send the specified buffer on the given channel
+ * @channel: Pointer to vmbus_channel structure
+ * @buffer: Pointer to the buffer you want to send the data from.
+ * @bufferlen: Maximum size of what the buffer holds.
+ * @requestid: Identifier of the request
+ * @type: Type of packet that is being sent e.g. negotiate, time
+ *	  packet etc.
+ * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
+ *
+ * Sends data in @buffer directly to Hyper-V via the vmbus.
+ * This will send the data unparsed to Hyper-V.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
+		     u32 bufferlen, u64 requestid,
+		     enum vmbus_packet_type type, u32 flags)
+{
+	return vmbus_sendpacket_getid(channel, buffer, bufferlen,
+				      requestid, NULL, type, flags);
+}
+EXPORT_SYMBOL(vmbus_sendpacket);
+
+/*
+ * vmbus_sendpacket_mpb_desc - Send one or more multi-page buffer packets
+ * using a GPADL Direct packet type.
+ * The desc argument must include space for the VMBus descriptor. The
+ * rangecount field must already be set.
+ */
+int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
+			      struct vmbus_packet_mpb_array *desc,
+			      u32 desc_size,
+			      void *buffer, u32 bufferlen, u64 requestid)
+{
+	u32 packetlen;
+	u32 packetlen_aligned;
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+
+	packetlen = desc_size + bufferlen;
+	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+	/* Setup the descriptor */
+	desc->type = VM_PKT_DATA_USING_GPA_DIRECT;
+	desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+	desc->dataoffset8 = desc_size >> 3; /* in 8-bytes granularity */
+	desc->length8 = (u16)(packetlen_aligned >> 3);
+	desc->transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
+	desc->reserved = 0;
+
+	bufferlist[0].iov_base = desc;
+	bufferlist[0].iov_len = desc_size;
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
+
+/**
+ * __vmbus_recvpacket() - Retrieve the user packet on the specified channel
+ * @channel: Pointer to vmbus_channel structure
+ * @buffer: Pointer to the buffer you want to receive the data into.
+ * @bufferlen: Maximum size of what the buffer can hold.
+ * @buffer_actual_len: The actual size of the data after it was received.
+ * @requestid: Identifier of the request
+ * @raw: true means keep the vmpacket_descriptor header in the received data.
+ *
+ * Receives directly from the hyper-v vmbus and puts the data it received
+ * into Buffer. This will receive the data unparsed from hyper-v.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+static inline int
+__vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
+		   u32 bufferlen, u32 *buffer_actual_len, u64 *requestid,
+		   bool raw)
+{
+	return hv_ringbuffer_read(channel, buffer, bufferlen,
+				  buffer_actual_len, requestid, raw);
+
+}
+
+int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
+		     u32 bufferlen, u32 *buffer_actual_len,
+		     u64 *requestid)
+{
+	return __vmbus_recvpacket(channel, buffer, bufferlen,
+				  buffer_actual_len, requestid, false);
+}
+EXPORT_SYMBOL(vmbus_recvpacket);
+
+/*
+ * vmbus_recvpacket_raw - Retrieve the raw packet on the specified channel
+ */
+int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
+			      u32 bufferlen, u32 *buffer_actual_len,
+			      u64 *requestid)
+{
+	return __vmbus_recvpacket(channel, buffer, bufferlen,
+				  buffer_actual_len, requestid, true);
+}
+EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
+
+/*
+ * vmbus_next_request_id - Returns a new request id. It is also
+ * the index at which the guest memory address is stored.
+ * Uses a spin lock to avoid race conditions.
+ * @channel: Pointer to the VMbus channel struct
+ * @rqst_add: Guest memory address to be stored in the array
+ */
+u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
+{
+	struct vmbus_requestor *rqstor = &channel->requestor;
+	unsigned long flags;
+	u64 current_id;
+
+	/* Check rqstor has been initialized */
+	if (!channel->rqstor_size)
+		return VMBUS_NO_RQSTOR;
+
+	lock_requestor(channel, flags);
+	current_id = rqstor->next_request_id;
+
+	/* Requestor array is full */
+	if (current_id >= rqstor->size) {
+		unlock_requestor(channel, flags);
+		return VMBUS_RQST_ERROR;
+	}
+
+	rqstor->next_request_id = rqstor->req_arr[current_id];
+	rqstor->req_arr[current_id] = rqst_addr;
+
+	/* The already held spin lock provides atomicity */
+	bitmap_set(rqstor->req_bitmap, current_id, 1);
+
+	unlock_requestor(channel, flags);
+
+	/*
+	 * Cannot return an ID of 0, which is reserved for an unsolicited
+	 * message from Hyper-V; Hyper-V does not acknowledge (respond to)
+	 * VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED requests with ID of
+	 * 0 sent by the guest.
+	 */
+	return current_id + 1;
+}
+EXPORT_SYMBOL_GPL(vmbus_next_request_id);
+
+/* As in vmbus_request_addr_match() but without the requestor lock */
+u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+			       u64 rqst_addr)
+{
+	struct vmbus_requestor *rqstor = &channel->requestor;
+	u64 req_addr;
+
+	/* Check rqstor has been initialized */
+	if (!channel->rqstor_size)
+		return VMBUS_NO_RQSTOR;
+
+	/* Hyper-V can send an unsolicited message with ID of 0 */
+	if (!trans_id)
+		return VMBUS_RQST_ERROR;
+
+	/* Data corresponding to trans_id is stored at trans_id - 1 */
+	trans_id--;
+
+	/* Invalid trans_id */
+	if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))
+		return VMBUS_RQST_ERROR;
+
+	req_addr = rqstor->req_arr[trans_id];
+	if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {
+		rqstor->req_arr[trans_id] = rqstor->next_request_id;
+		rqstor->next_request_id = trans_id;
+
+		/* The already held spin lock provides atomicity */
+		bitmap_clear(rqstor->req_bitmap, trans_id, 1);
+	}
+
+	return req_addr;
+}
+EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
+
+/*
+ * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's
+ * requestor, provided the memory address stored at @trans_id equals @rqst_addr
+ * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).
+ *
+ * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if
+ * @trans_id is not contained in the requestor.
+ *
+ * Acquires and releases the requestor spin lock.
+ */
+u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+			     u64 rqst_addr)
+{
+	unsigned long flags;
+	u64 req_addr;
+
+	lock_requestor(channel, flags);
+	req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
+	unlock_requestor(channel, flags);
+
+	return req_addr;
+}
+EXPORT_SYMBOL_GPL(vmbus_request_addr_match);
+
+/*
+ * vmbus_request_addr - Returns the memory address stored at @trans_id
+ * in @rqstor. Uses a spin lock to avoid race conditions.
+ * @channel: Pointer to the VMbus channel struct
+ * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
+ * next request id.
+ */
+u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
+{
+	return vmbus_request_addr_match(channel, trans_id, VMBUS_RQST_ADDR_ANY);
+}
+EXPORT_SYMBOL_GPL(vmbus_request_addr);
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
new file mode 100644
index 000000000..a044fd3b3
--- /dev/null
+++ b/drivers/hv/channel_mgmt.c
@@ -0,0 +1,1686 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/cpu.h>
+#include <linux/hyperv.h>
+#include <linux/export.h>
+#include <asm/mshyperv.h>
+#include <linux/sched/isolation.h>
+
+#include "hyperv_vmbus.h"
+
+static void init_vp_index(struct vmbus_channel *channel);
+
+const struct vmbus_device vmbus_devs[] = {
+	/* IDE */
+	{ .dev_type = HV_IDE,
+	  HV_IDE_GUID,
+	  .perf_device = true,
+	  .allowed_in_isolated = false,
+	},
+
+	/* SCSI */
+	{ .dev_type = HV_SCSI,
+	  HV_SCSI_GUID,
+	  .perf_device = true,
+	  .allowed_in_isolated = true,
+	},
+
+	/* Fibre Channel */
+	{ .dev_type = HV_FC,
+	  HV_SYNTHFC_GUID,
+	  .perf_device = true,
+	  .allowed_in_isolated = false,
+	},
+
+	/* Synthetic NIC */
+	{ .dev_type = HV_NIC,
+	  HV_NIC_GUID,
+	  .perf_device = true,
+	  .allowed_in_isolated = true,
+	},
+
+	/* Network Direct */
+	{ .dev_type = HV_ND,
+	  HV_ND_GUID,
+	  .perf_device = true,
+	  .allowed_in_isolated = false,
+	},
+
+	/* PCIE */
+	{ .dev_type = HV_PCIE,
+	  HV_PCIE_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = true,
+	},
+
+	/* Synthetic Frame Buffer */
+	{ .dev_type = HV_FB,
+	  HV_SYNTHVID_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/* Synthetic Keyboard */
+	{ .dev_type = HV_KBD,
+	  HV_KBD_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/* Synthetic MOUSE */
+	{ .dev_type = HV_MOUSE,
+	  HV_MOUSE_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/* KVP */
+	{ .dev_type = HV_KVP,
+	  HV_KVP_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/* Time Synch */
+	{ .dev_type = HV_TS,
+	  HV_TS_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = true,
+	},
+
+	/* Heartbeat */
+	{ .dev_type = HV_HB,
+	  HV_HEART_BEAT_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = true,
+	},
+
+	/* Shutdown */
+	{ .dev_type = HV_SHUTDOWN,
+	  HV_SHUTDOWN_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = true,
+	},
+
+	/* File copy */
+	/* fcopy always uses 16KB ring buffer size and is working well for last many years */
+	{ .pref_ring_size = 0x4000,
+	  .dev_type = HV_FCOPY,
+	  HV_FCOPY_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/* Backup */
+	{ .dev_type = HV_BACKUP,
+	  HV_VSS_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/* Dynamic Memory */
+	{ .dev_type = HV_DM,
+	  HV_DM_GUID,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+
+	/*
+	 * Unknown GUID
+	 * 64 KB ring buffer + 4 KB header should be sufficient size for any Hyper-V device apart
+	 * from HV_NIC and HV_SCSI. This case avoid the fallback for unknown devices to allocate
+	 * much bigger (2 MB) of ring size.
+	 */
+	{ .pref_ring_size = 0x11000,
+	  .dev_type = HV_UNKNOWN,
+	  .perf_device = false,
+	  .allowed_in_isolated = false,
+	},
+};
+EXPORT_SYMBOL_GPL(vmbus_devs);
+
+static const struct {
+	guid_t guid;
+} vmbus_unsupported_devs[] = {
+	{ HV_AVMA1_GUID },
+	{ HV_AVMA2_GUID },
+	{ HV_RDV_GUID	},
+	{ HV_IMC_GUID	},
+};
+
+/*
+ * The rescinded channel may be blocked waiting for a response from the host;
+ * take care of that.
+ */
+static void vmbus_rescind_cleanup(struct vmbus_channel *channel)
+{
+	struct vmbus_channel_msginfo *msginfo;
+	unsigned long flags;
+
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	channel->rescind = true;
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+
+		if (msginfo->waiting_channel == channel) {
+			complete(&msginfo->waitevent);
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+static bool is_unsupported_vmbus_devs(const guid_t *guid)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vmbus_unsupported_devs); i++)
+		if (guid_equal(guid, &vmbus_unsupported_devs[i].guid))
+			return true;
+	return false;
+}
+
+static u16 hv_get_dev_type(const struct vmbus_channel *channel)
+{
+	const guid_t *guid = &channel->offermsg.offer.if_type;
+	u16 i;
+
+	if (is_hvsock_channel(channel) || is_unsupported_vmbus_devs(guid))
+		return HV_UNKNOWN;
+
+	for (i = HV_IDE; i < HV_UNKNOWN; i++) {
+		if (guid_equal(guid, &vmbus_devs[i].guid))
+			return i;
+	}
+	pr_info("Unknown GUID: %pUl\n", guid);
+	return i;
+}
+
+/**
+ * vmbus_prep_negotiate_resp() - Create default response for Negotiate message
+ * @icmsghdrp: Pointer to msg header structure
+ * @buf: Raw buffer channel data
+ * @buflen: Length of the raw buffer channel data.
+ * @fw_version: The framework versions we can support.
+ * @fw_vercnt: The size of @fw_version.
+ * @srv_version: The service versions we can support.
+ * @srv_vercnt: The size of @srv_version.
+ * @nego_fw_version: The selected framework version.
+ * @nego_srv_version: The selected service version.
+ *
+ * Note: Versions are given in decreasing order.
+ *
+ * Set up and fill in default negotiate response message.
+ * Mainly used by Hyper-V drivers.
+ */
+bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, u8 *buf,
+				u32 buflen, const int *fw_version, int fw_vercnt,
+				const int *srv_version, int srv_vercnt,
+				int *nego_fw_version, int *nego_srv_version)
+{
+	int icframe_major, icframe_minor;
+	int icmsg_major, icmsg_minor;
+	int fw_major, fw_minor;
+	int srv_major, srv_minor;
+	int i, j;
+	bool found_match = false;
+	struct icmsg_negotiate *negop;
+
+	/* Check that there's enough space for icframe_vercnt, icmsg_vercnt */
+	if (buflen < ICMSG_HDR + offsetof(struct icmsg_negotiate, reserved)) {
+		pr_err_ratelimited("Invalid icmsg negotiate\n");
+		return false;
+	}
+
+	icmsghdrp->icmsgsize = 0x10;
+	negop = (struct icmsg_negotiate *)&buf[ICMSG_HDR];
+
+	icframe_major = negop->icframe_vercnt;
+	icframe_minor = 0;
+
+	icmsg_major = negop->icmsg_vercnt;
+	icmsg_minor = 0;
+
+	/* Validate negop packet */
+	if (icframe_major > IC_VERSION_NEGOTIATION_MAX_VER_COUNT ||
+	    icmsg_major > IC_VERSION_NEGOTIATION_MAX_VER_COUNT ||
+	    ICMSG_NEGOTIATE_PKT_SIZE(icframe_major, icmsg_major) > buflen) {
+		pr_err_ratelimited("Invalid icmsg negotiate - icframe_major: %u, icmsg_major: %u\n",
+				   icframe_major, icmsg_major);
+		goto fw_error;
+	}
+
+	/*
+	 * Select the framework version number we will
+	 * support.
+	 */
+
+	for (i = 0; i < fw_vercnt; i++) {
+		fw_major = (fw_version[i] >> 16);
+		fw_minor = (fw_version[i] & 0xFFFF);
+
+		for (j = 0; j < negop->icframe_vercnt; j++) {
+			if ((negop->icversion_data[j].major == fw_major) &&
+			    (negop->icversion_data[j].minor == fw_minor)) {
+				icframe_major = negop->icversion_data[j].major;
+				icframe_minor = negop->icversion_data[j].minor;
+				found_match = true;
+				break;
+			}
+		}
+
+		if (found_match)
+			break;
+	}
+
+	if (!found_match)
+		goto fw_error;
+
+	found_match = false;
+
+	for (i = 0; i < srv_vercnt; i++) {
+		srv_major = (srv_version[i] >> 16);
+		srv_minor = (srv_version[i] & 0xFFFF);
+
+		for (j = negop->icframe_vercnt;
+			(j < negop->icframe_vercnt + negop->icmsg_vercnt);
+			j++) {
+
+			if ((negop->icversion_data[j].major == srv_major) &&
+				(negop->icversion_data[j].minor == srv_minor)) {
+
+				icmsg_major = negop->icversion_data[j].major;
+				icmsg_minor = negop->icversion_data[j].minor;
+				found_match = true;
+				break;
+			}
+		}
+
+		if (found_match)
+			break;
+	}
+
+	/*
+	 * Respond with the framework and service
+	 * version numbers we can support.
+	 */
+
+fw_error:
+	if (!found_match) {
+		negop->icframe_vercnt = 0;
+		negop->icmsg_vercnt = 0;
+	} else {
+		negop->icframe_vercnt = 1;
+		negop->icmsg_vercnt = 1;
+	}
+
+	if (nego_fw_version)
+		*nego_fw_version = (icframe_major << 16) | icframe_minor;
+
+	if (nego_srv_version)
+		*nego_srv_version = (icmsg_major << 16) | icmsg_minor;
+
+	negop->icversion_data[0].major = icframe_major;
+	negop->icversion_data[0].minor = icframe_minor;
+	negop->icversion_data[1].major = icmsg_major;
+	negop->icversion_data[1].minor = icmsg_minor;
+	return found_match;
+}
+EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
+
+/*
+ * alloc_channel - Allocate and initialize a vmbus channel object
+ */
+static struct vmbus_channel *alloc_channel(void)
+{
+	struct vmbus_channel *channel;
+
+	channel = kzalloc_obj(*channel, GFP_ATOMIC);
+	if (!channel)
+		return NULL;
+
+	spin_lock_init(&channel->sched_lock);
+	init_completion(&channel->rescind_event);
+
+	INIT_LIST_HEAD(&channel->sc_list);
+
+	tasklet_init(&channel->callback_event,
+		     vmbus_on_event, (unsigned long)channel);
+
+	hv_ringbuffer_pre_init(channel);
+
+	return channel;
+}
+
+/*
+ * free_channel - Release the resources used by the vmbus channel object
+ */
+static void free_channel(struct vmbus_channel *channel)
+{
+	tasklet_kill(&channel->callback_event);
+	vmbus_remove_channel_attr_group(channel);
+
+	kobject_put(&channel->kobj);
+}
+
+void vmbus_channel_map_relid(struct vmbus_channel *channel)
+{
+	u32 new_relid = channel->offermsg.child_relid;
+
+	if (WARN_ON(new_relid >= MAX_CHANNEL_RELIDS))
+		return;
+
+	/*
+	 * This function is always called in the tasklet for the connect CPU.
+	 * So updating the relid hiwater mark does not need to be atomic.
+	 */
+	if (new_relid > READ_ONCE(vmbus_connection.relid_hiwater))
+		WRITE_ONCE(vmbus_connection.relid_hiwater, new_relid);
+
+	/*
+	 * The mapping of the channel's relid is visible from the CPUs that
+	 * execute vmbus_chan_sched() by the time that vmbus_chan_sched() will
+	 * execute:
+	 *
+	 *  (a) In the "normal (i.e., not resuming from hibernation)" path,
+	 *      the full barrier in virt_store_mb() guarantees that the store
+	 *      is propagated to all CPUs before the add_channel_work work
+	 *      is queued.  In turn, add_channel_work is queued before the
+	 *      channel's ring buffer is allocated/initialized and the
+	 *      OPENCHANNEL message for the channel is sent in vmbus_open().
+	 *      Hyper-V won't start sending the interrupts for the channel
+	 *      before the OPENCHANNEL message is acked.  The memory barrier
+	 *      in vmbus_chan_sched() -> sync_test_and_clear_bit() ensures
+	 *      that vmbus_chan_sched() must find the channel's relid in
+	 *      recv_int_page before retrieving the channel pointer from the
+	 *      array of channels.
+	 *
+	 *  (b) In the "resuming from hibernation" path, the virt_store_mb()
+	 *      guarantees that the store is propagated to all CPUs before
+	 *      the VMBus connection is marked as ready for the resume event
+	 *      (cf. check_ready_for_resume_event()).  The interrupt handler
+	 *      of the VMBus driver and vmbus_chan_sched() can not run before
+	 *      vmbus_bus_resume() has completed execution (cf. resume_noirq).
+	 */
+	virt_store_mb(vmbus_connection.channels[new_relid], channel);
+}
+
+void vmbus_channel_unmap_relid(struct vmbus_channel *channel)
+{
+	if (WARN_ON(channel->offermsg.child_relid >= MAX_CHANNEL_RELIDS))
+		return;
+	WRITE_ONCE(
+		vmbus_connection.channels[channel->offermsg.child_relid],
+		NULL);
+}
+
+static void vmbus_release_relid(u32 relid)
+{
+	struct vmbus_channel_relid_released msg;
+	int ret;
+
+	memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
+	msg.child_relid = relid;
+	msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
+	ret = vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released),
+			     true);
+
+	trace_vmbus_release_relid(&msg, ret);
+}
+
+void hv_process_channel_removal(struct vmbus_channel *channel)
+{
+	lockdep_assert_held(&vmbus_connection.channel_mutex);
+	BUG_ON(!channel->rescind);
+
+	/*
+	 * hv_process_channel_removal() could find INVALID_RELID only for
+	 * hv_sock channels.  See the inline comments in vmbus_onoffer().
+	 */
+	WARN_ON(channel->offermsg.child_relid == INVALID_RELID &&
+		!is_hvsock_channel(channel));
+
+	/*
+	 * Upon suspend, an in-use hv_sock channel is removed from the array of
+	 * channels and the relid is invalidated.  After hibernation, when the
+	 * user-space application destroys the channel, it's unnecessary and
+	 * unsafe to remove the channel from the array of channels.  See also
+	 * the inline comments before the call of vmbus_release_relid() below.
+	 */
+	if (channel->offermsg.child_relid != INVALID_RELID)
+		vmbus_channel_unmap_relid(channel);
+
+	if (channel->primary_channel == NULL)
+		list_del(&channel->listentry);
+	else
+		list_del(&channel->sc_list);
+
+	/*
+	 * If this is a "perf" channel, updates the hv_numa_map[] masks so that
+	 * init_vp_index() can (re-)use the CPU.
+	 */
+	if (hv_is_perf_channel(channel))
+		hv_clear_allocated_cpu(channel->target_cpu);
+
+	/*
+	 * Upon suspend, an in-use hv_sock channel is marked as "rescinded" and
+	 * the relid is invalidated; after hibernation, when the user-space app
+	 * destroys the channel, the relid is INVALID_RELID, and in this case
+	 * it's unnecessary and unsafe to release the old relid, since the same
+	 * relid can refer to a completely different channel now.
+	 */
+	if (channel->offermsg.child_relid != INVALID_RELID)
+		vmbus_release_relid(channel->offermsg.child_relid);
+
+	free_channel(channel);
+}
+
+void vmbus_free_channels(void)
+{
+	struct vmbus_channel *channel, *tmp;
+
+	list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,
+		listentry) {
+		/* hv_process_channel_removal() needs this */
+		channel->rescind = true;
+
+		vmbus_device_unregister(channel->device_obj);
+	}
+}
+
+/* Note: the function can run concurrently for primary/sub channels. */
+static void vmbus_add_channel_work(struct work_struct *work)
+{
+	struct vmbus_channel *newchannel =
+		container_of(work, struct vmbus_channel, add_channel_work);
+	struct vmbus_channel *primary_channel = newchannel->primary_channel;
+	int ret;
+
+	/*
+	 * This state is used to indicate a successful open
+	 * so that when we do close the channel normally, we
+	 * can cleanup properly.
+	 */
+	newchannel->state = CHANNEL_OPEN_STATE;
+
+	if (primary_channel != NULL) {
+		/* newchannel is a sub-channel. */
+		struct hv_device *dev = primary_channel->device_obj;
+
+		if (vmbus_add_channel_kobj(dev, newchannel))
+			goto err_deq_chan;
+
+		if (primary_channel->sc_creation_callback != NULL)
+			primary_channel->sc_creation_callback(newchannel);
+
+		newchannel->probe_done = true;
+		return;
+	}
+
+	/*
+	 * Start the process of binding the primary channel to the driver
+	 */
+	newchannel->device_obj = vmbus_device_create(
+		&newchannel->offermsg.offer.if_type,
+		&newchannel->offermsg.offer.if_instance,
+		newchannel);
+	if (!newchannel->device_obj)
+		goto err_deq_chan;
+
+	newchannel->device_obj->device_id = newchannel->device_id;
+	/*
+	 * Add the new device to the bus. This will kick off device-driver
+	 * binding which eventually invokes the device driver's AddDevice()
+	 * method.
+	 *
+	 * If vmbus_device_register() fails, the 'device_obj' is freed in
+	 * vmbus_device_release() as called by device_unregister() in the
+	 * error path of vmbus_device_register(). In the outside error
+	 * path, there's no need to free it.
+	 */
+	ret = vmbus_device_register(newchannel->device_obj);
+
+	if (ret != 0) {
+		pr_err("unable to add child device object (relid %d)\n",
+			newchannel->offermsg.child_relid);
+		goto err_deq_chan;
+	}
+
+	newchannel->probe_done = true;
+	return;
+
+err_deq_chan:
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	/*
+	 * We need to set the flag, otherwise
+	 * vmbus_onoffer_rescind() can be blocked.
+	 */
+	newchannel->probe_done = true;
+
+	if (primary_channel == NULL)
+		list_del(&newchannel->listentry);
+	else
+		list_del(&newchannel->sc_list);
+
+	/* vmbus_process_offer() has mapped the channel. */
+	vmbus_channel_unmap_relid(newchannel);
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	vmbus_release_relid(newchannel->offermsg.child_relid);
+
+	free_channel(newchannel);
+}
+
+/*
+ * vmbus_process_offer - Process the offer by creating a channel/device
+ * associated with this offer
+ */
+static void vmbus_process_offer(struct vmbus_channel *newchannel)
+{
+	struct vmbus_channel *channel;
+	struct workqueue_struct *wq;
+	bool fnew = true;
+
+	/*
+	 * Synchronize vmbus_process_offer() and CPU hotplugging:
+	 *
+	 * CPU1				CPU2
+	 *
+	 * [vmbus_process_offer()]	[Hot removal of the CPU]
+	 *
+	 * CPU_READ_LOCK		CPUS_WRITE_LOCK
+	 * LOAD cpu_online_mask		SEARCH chn_list
+	 * STORE target_cpu		LOAD target_cpu
+	 * INSERT chn_list		STORE cpu_online_mask
+	 * CPUS_READ_UNLOCK		CPUS_WRITE_UNLOCK
+	 *
+	 * Forbids: CPU1's LOAD from *not* seing CPU2's STORE &&
+	 *              CPU2's SEARCH from *not* seeing CPU1's INSERT
+	 *
+	 * Forbids: CPU2's SEARCH from seeing CPU1's INSERT &&
+	 *              CPU2's LOAD from *not* seing CPU1's STORE
+	 */
+	cpus_read_lock();
+
+	/*
+	 * Serializes the modifications of the chn_list list as well as
+	 * the accesses to next_numa_node_id in init_vp_index().
+	 */
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (guid_equal(&channel->offermsg.offer.if_type,
+			       &newchannel->offermsg.offer.if_type) &&
+		    guid_equal(&channel->offermsg.offer.if_instance,
+			       &newchannel->offermsg.offer.if_instance)) {
+			fnew = false;
+			newchannel->primary_channel = channel;
+			break;
+		}
+	}
+
+	init_vp_index(newchannel);
+
+	/* Remember the channels that should be cleaned up upon suspend. */
+	if (is_hvsock_channel(newchannel) || is_sub_channel(newchannel))
+		atomic_inc(&vmbus_connection.nr_chan_close_on_suspend);
+
+	/*
+	 * Now that we have acquired the channel_mutex,
+	 * we can release the potentially racing rescind thread.
+	 */
+	atomic_dec(&vmbus_connection.offer_in_progress);
+
+	if (fnew) {
+		list_add_tail(&newchannel->listentry,
+			      &vmbus_connection.chn_list);
+	} else {
+		/*
+		 * Check to see if this is a valid sub-channel.
+		 */
+		if (newchannel->offermsg.offer.sub_channel_index == 0) {
+			mutex_unlock(&vmbus_connection.channel_mutex);
+			cpus_read_unlock();
+			/*
+			 * Don't call free_channel(), because newchannel->kobj
+			 * is not initialized yet.
+			 */
+			kfree(newchannel);
+			WARN_ON_ONCE(1);
+			return;
+		}
+		/*
+		 * Process the sub-channel.
+		 */
+		list_add_tail(&newchannel->sc_list, &channel->sc_list);
+	}
+
+	vmbus_channel_map_relid(newchannel);
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+	cpus_read_unlock();
+
+	/*
+	 * vmbus_process_offer() mustn't call channel->sc_creation_callback()
+	 * directly for sub-channels, because sc_creation_callback() ->
+	 * vmbus_open() may never get the host's response to the
+	 * OPEN_CHANNEL message (the host may rescind a channel at any time,
+	 * e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind()
+	 * may not wake up the vmbus_open() as it's blocked due to a non-zero
+	 * vmbus_connection.offer_in_progress, and finally we have a deadlock.
+	 *
+	 * The above is also true for primary channels, if the related device
+	 * drivers use sync probing mode by default.
+	 *
+	 * And, usually the handling of primary channels and sub-channels can
+	 * depend on each other, so we should offload them to different
+	 * workqueues to avoid possible deadlock, e.g. in sync-probing mode,
+	 * NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() ->
+	 * rtnl_lock(), and causes deadlock: the former gets the rtnl_lock
+	 * and waits for all the sub-channels to appear, but the latter
+	 * can't get the rtnl_lock and this blocks the handling of
+	 * sub-channels.
+	 */
+	INIT_WORK(&newchannel->add_channel_work, vmbus_add_channel_work);
+	wq = fnew ? vmbus_connection.handle_primary_chan_wq :
+		    vmbus_connection.handle_sub_chan_wq;
+	queue_work(wq, &newchannel->add_channel_work);
+}
+
+/*
+ * Check if CPUs used by other channels of the same device.
+ * It should only be called by init_vp_index().
+ */
+static bool hv_cpuself_used(u32 cpu, struct vmbus_channel *chn)
+{
+	struct vmbus_channel *primary = chn->primary_channel;
+	struct vmbus_channel *sc;
+
+	lockdep_assert_held(&vmbus_connection.channel_mutex);
+
+	if (!primary)
+		return false;
+
+	if (primary->target_cpu == cpu)
+		return true;
+
+	list_for_each_entry(sc, &primary->sc_list, sc_list)
+		if (sc != chn && sc->target_cpu == cpu)
+			return true;
+
+	return false;
+}
+
+/*
+ * We use this state to statically distribute the channel interrupt load.
+ */
+static int next_numa_node_id;
+
+/*
+ * We can statically distribute the incoming channel interrupt load
+ * by binding a channel to VCPU.
+ *
+ * For non-performance critical channels we assign the VMBUS_CONNECT_CPU.
+ * Performance critical channels will be distributed evenly among all
+ * the available NUMA nodes.  Once the node is assigned, we will assign
+ * the CPU based on a simple round robin scheme.
+ */
+static void init_vp_index(struct vmbus_channel *channel)
+{
+	bool perf_chn = hv_is_perf_channel(channel);
+	u32 i, ncpu = num_online_cpus();
+	cpumask_var_t available_mask;
+	struct cpumask *allocated_mask;
+	const struct cpumask *hk_mask = housekeeping_cpumask(HK_TYPE_MANAGED_IRQ);
+	u32 target_cpu;
+	int numa_node;
+
+	if (!perf_chn ||
+	    !alloc_cpumask_var(&available_mask, GFP_KERNEL) ||
+	    cpumask_empty(hk_mask)) {
+		/*
+		 * If the channel is not a performance critical
+		 * channel, bind it to VMBUS_CONNECT_CPU.
+		 * In case alloc_cpumask_var() fails, bind it to
+		 * VMBUS_CONNECT_CPU.
+		 * If all the cpus are isolated, bind it to
+		 * VMBUS_CONNECT_CPU.
+		 */
+		channel->target_cpu = VMBUS_CONNECT_CPU;
+		if (perf_chn)
+			hv_set_allocated_cpu(VMBUS_CONNECT_CPU);
+		return;
+	}
+
+	for (i = 1; i <= ncpu + 1; i++) {
+		while (true) {
+			numa_node = next_numa_node_id++;
+			if (numa_node == nr_node_ids) {
+				next_numa_node_id = 0;
+				continue;
+			}
+			if (cpumask_empty(cpumask_of_node(numa_node)))
+				continue;
+			break;
+		}
+		allocated_mask = &hv_context.hv_numa_map[numa_node];
+
+retry:
+		cpumask_xor(available_mask, allocated_mask, cpumask_of_node(numa_node));
+		cpumask_and(available_mask, available_mask, hk_mask);
+
+		if (cpumask_empty(available_mask)) {
+			/*
+			 * We have cycled through all the CPUs in the node;
+			 * reset the allocated map.
+			 */
+			cpumask_clear(allocated_mask);
+			goto retry;
+		}
+
+		target_cpu = cpumask_first(available_mask);
+		cpumask_set_cpu(target_cpu, allocated_mask);
+
+		if (channel->offermsg.offer.sub_channel_index >= ncpu ||
+		    i > ncpu || !hv_cpuself_used(target_cpu, channel))
+			break;
+	}
+
+	channel->target_cpu = target_cpu;
+
+	free_cpumask_var(available_mask);
+}
+
+#define UNLOAD_DELAY_UNIT_MS	10		/* 10 milliseconds */
+#define UNLOAD_WAIT_MS		(100*1000)	/* 100 seconds */
+#define UNLOAD_WAIT_LOOPS	(UNLOAD_WAIT_MS/UNLOAD_DELAY_UNIT_MS)
+#define UNLOAD_MSG_MS		(5*1000)	/* Every 5 seconds */
+#define UNLOAD_MSG_LOOPS	(UNLOAD_MSG_MS/UNLOAD_DELAY_UNIT_MS)
+
+static void vmbus_wait_for_unload(void)
+{
+	int cpu;
+	void *page_addr;
+	struct hv_message *msg;
+	struct vmbus_channel_message_header *hdr;
+	u32 message_type, i;
+
+	/*
+	 * CHANNELMSG_UNLOAD_RESPONSE is always delivered to the CPU which was
+	 * used for initial contact or to CPU0 depending on host version. When
+	 * we're crashing on a different CPU let's hope that IRQ handler on
+	 * the cpu which receives CHANNELMSG_UNLOAD_RESPONSE is still
+	 * functional and vmbus_unload_response() will complete
+	 * vmbus_connection.unload_event. If not, the last thing we can do is
+	 * read message pages for all CPUs directly.
+	 *
+	 * Wait up to 100 seconds since an Azure host must writeback any dirty
+	 * data in its disk cache before the VMbus UNLOAD request will
+	 * complete. This flushing has been empirically observed to take up
+	 * to 50 seconds in cases with a lot of dirty data, so allow additional
+	 * leeway and for inaccuracies in mdelay(). But eventually time out so
+	 * that the panic path can't get hung forever in case the response
+	 * message isn't seen.
+	 */
+	for (i = 1; i <= UNLOAD_WAIT_LOOPS; i++) {
+		if (completion_done(&vmbus_connection.unload_event))
+			goto completed;
+
+		for_each_present_cpu(cpu) {
+			struct hv_per_cpu_context *hv_cpu
+				= per_cpu_ptr(hv_context.cpu_context, cpu);
+
+			/*
+			 * In a CoCo VM the hyp_synic_message_page is not allocated
+			 * in hv_synic_alloc(). Instead it is set/cleared in
+			 * hv_hyp_synic_enable_regs() and hv_hyp_synic_disable_regs()
+			 * such that it is set only when the CPU is online. If
+			 * not all present CPUs are online, the message page
+			 * might be NULL, so skip such CPUs.
+			 */
+			page_addr = hv_cpu->hyp_synic_message_page;
+			if (!page_addr)
+				continue;
+
+			msg = (struct hv_message *)page_addr
+				+ VMBUS_MESSAGE_SINT;
+
+			message_type = READ_ONCE(msg->header.message_type);
+			if (message_type == HVMSG_NONE)
+				continue;
+
+			hdr = (struct vmbus_channel_message_header *)
+				msg->u.payload;
+
+			if (hdr->msgtype == CHANNELMSG_UNLOAD_RESPONSE)
+				complete(&vmbus_connection.unload_event);
+
+			vmbus_signal_eom(msg, message_type);
+		}
+
+		/*
+		 * Give a notice periodically so someone watching the
+		 * serial output won't think it is completely hung.
+		 */
+		if (!(i % UNLOAD_MSG_LOOPS))
+			pr_notice("Waiting for VMBus UNLOAD to complete\n");
+
+		mdelay(UNLOAD_DELAY_UNIT_MS);
+	}
+	pr_err("Continuing even though VMBus UNLOAD did not complete\n");
+
+completed:
+	/*
+	 * We're crashing and already got the UNLOAD_RESPONSE, cleanup all
+	 * maybe-pending messages on all CPUs to be able to receive new
+	 * messages after we reconnect.
+	 */
+	for_each_present_cpu(cpu) {
+		struct hv_per_cpu_context *hv_cpu
+			= per_cpu_ptr(hv_context.cpu_context, cpu);
+
+		page_addr = hv_cpu->hyp_synic_message_page;
+		if (!page_addr)
+			continue;
+
+		msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
+		msg->header.message_type = HVMSG_NONE;
+	}
+}
+
+/*
+ * vmbus_unload_response - Handler for the unload response.
+ */
+static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
+{
+	/*
+	 * This is a global event; just wakeup the waiting thread.
+	 * Once we successfully unload, we can cleanup the monitor state.
+	 *
+	 * NB.  A malicious or compromised Hyper-V could send a spurious
+	 * message of type CHANNELMSG_UNLOAD_RESPONSE, and trigger a call
+	 * of the complete() below.  Make sure that unload_event has been
+	 * initialized by the time this complete() is executed.
+	 */
+	complete(&vmbus_connection.unload_event);
+}
+
+void vmbus_initiate_unload(bool crash)
+{
+	struct vmbus_channel_message_header hdr;
+	enum vmbus_connect_state old_state;
+
+	old_state = xchg(&vmbus_connection.conn_state, DISCONNECTED);
+	if (old_state == DISCONNECTED || old_state == CONNECTING)
+		return;
+
+	reinit_completion(&vmbus_connection.unload_event);
+	memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
+	hdr.msgtype = CHANNELMSG_UNLOAD;
+	vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header),
+		       !crash);
+
+	/*
+	 * vmbus_initiate_unload() is also called on crash and the crash can be
+	 * happening in an interrupt context, where scheduling is impossible.
+	 */
+	if (!crash)
+		wait_for_completion(&vmbus_connection.unload_event);
+	else
+		vmbus_wait_for_unload();
+}
+EXPORT_SYMBOL_GPL(vmbus_initiate_unload);
+
+static void vmbus_setup_channel_state(struct vmbus_channel *channel,
+				      struct vmbus_channel_offer_channel *offer)
+{
+	/*
+	 * Setup state for signalling the host.
+	 */
+	channel->sig_event = VMBUS_EVENT_CONNECTION_ID;
+
+	channel->is_dedicated_interrupt =
+			(offer->is_dedicated_interrupt != 0);
+	channel->sig_event = offer->connection_id;
+
+	memcpy(&channel->offermsg, offer,
+	       sizeof(struct vmbus_channel_offer_channel));
+	channel->monitor_grp = (u8)offer->monitorid / 32;
+	channel->monitor_bit = (u8)offer->monitorid % 32;
+	channel->device_id = hv_get_dev_type(channel);
+}
+
+/*
+ * find_primary_channel_by_offer - Get the channel object given the new offer.
+ * This is only used in the resume path of hibernation.
+ */
+static struct vmbus_channel *
+find_primary_channel_by_offer(const struct vmbus_channel_offer_channel *offer)
+{
+	struct vmbus_channel *channel = NULL, *iter;
+	const guid_t *inst1, *inst2;
+
+	/* Ignore sub-channel offers. */
+	if (offer->offer.sub_channel_index != 0)
+		return NULL;
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	list_for_each_entry(iter, &vmbus_connection.chn_list, listentry) {
+		inst1 = &iter->offermsg.offer.if_instance;
+		inst2 = &offer->offer.if_instance;
+
+		if (guid_equal(inst1, inst2)) {
+			channel = iter;
+			break;
+		}
+	}
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	return channel;
+}
+
+static bool vmbus_is_valid_offer(const struct vmbus_channel_offer_channel *offer)
+{
+	const guid_t *guid = &offer->offer.if_type;
+	u16 i;
+
+	if (!hv_is_isolation_supported())
+		return true;
+
+	if (is_hvsock_offer(offer))
+		return true;
+
+	for (i = 0; i < ARRAY_SIZE(vmbus_devs); i++) {
+		if (guid_equal(guid, &vmbus_devs[i].guid))
+			return vmbus_devs[i].allowed_in_isolated;
+	}
+	return false;
+}
+
+/*
+ * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
+ *
+ */
+static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_offer_channel *offer;
+	struct vmbus_channel *oldchannel, *newchannel;
+	size_t offer_sz;
+	bool co_ring_buffer, co_external_memory;
+
+	offer = (struct vmbus_channel_offer_channel *)hdr;
+
+	trace_vmbus_onoffer(offer);
+
+	if (!vmbus_is_valid_offer(offer)) {
+		pr_err_ratelimited("Invalid offer %d from the host supporting isolation\n",
+				   offer->child_relid);
+		atomic_dec(&vmbus_connection.offer_in_progress);
+		return;
+	}
+
+	co_ring_buffer = is_co_ring_buffer(offer);
+	co_external_memory = is_co_external_memory(offer);
+	if (!co_ring_buffer && co_external_memory) {
+		pr_err("Invalid offer relid=%d: the ring buffer isn't encrypted\n",
+			offer->child_relid);
+		return;
+	}
+	if (co_ring_buffer || co_external_memory) {
+		if (vmbus_proto_version < VERSION_WIN10_V6_0 || !vmbus_is_confidential()) {
+			pr_err("Invalid offer relid=%d: no support for confidential VMBus\n",
+				offer->child_relid);
+			atomic_dec(&vmbus_connection.offer_in_progress);
+			return;
+		}
+	}
+
+	oldchannel = find_primary_channel_by_offer(offer);
+
+	if (oldchannel != NULL) {
+		/*
+		 * We're resuming from hibernation: all the sub-channel and
+		 * hv_sock channels we had before the hibernation should have
+		 * been cleaned up, and now we must be seeing a re-offered
+		 * primary channel that we had before the hibernation.
+		 */
+
+		/*
+		 * { Initially: channel relid = INVALID_RELID,
+		 *		channels[valid_relid] = NULL }
+		 *
+		 * CPU1					CPU2
+		 *
+		 * [vmbus_onoffer()]			[vmbus_device_release()]
+		 *
+		 * LOCK channel_mutex			LOCK channel_mutex
+		 * STORE channel relid = valid_relid	LOAD r1 = channel relid
+		 * MAP_RELID channel			if (r1 != INVALID_RELID)
+		 * UNLOCK channel_mutex			  UNMAP_RELID channel
+		 *					UNLOCK channel_mutex
+		 *
+		 * Forbids: r1 == valid_relid &&
+		 *              channels[valid_relid] == channel
+		 *
+		 * Note.  r1 can be INVALID_RELID only for an hv_sock channel.
+		 * None of the hv_sock channels which were present before the
+		 * suspend are re-offered upon the resume.  See the WARN_ON()
+		 * in hv_process_channel_removal().
+		 */
+		mutex_lock(&vmbus_connection.channel_mutex);
+
+		atomic_dec(&vmbus_connection.offer_in_progress);
+
+		WARN_ON(oldchannel->offermsg.child_relid != INVALID_RELID);
+		/* Fix up the relid. */
+		oldchannel->offermsg.child_relid = offer->child_relid;
+
+		offer_sz = sizeof(*offer);
+		if (memcmp(offer, &oldchannel->offermsg, offer_sz) != 0) {
+			/*
+			 * This is not an error, since the host can also change
+			 * the other field(s) of the offer, e.g. on WS RS5
+			 * (Build 17763), the offer->connection_id of the
+			 * Mellanox VF vmbus device can change when the host
+			 * reoffers the device upon resume.
+			 */
+			pr_debug("vmbus offer changed: relid=%d\n",
+				 offer->child_relid);
+
+			print_hex_dump_debug("Old vmbus offer: ",
+					     DUMP_PREFIX_OFFSET, 16, 4,
+					     &oldchannel->offermsg, offer_sz,
+					     false);
+			print_hex_dump_debug("New vmbus offer: ",
+					     DUMP_PREFIX_OFFSET, 16, 4,
+					     offer, offer_sz, false);
+
+			/* Fix up the old channel. */
+			vmbus_setup_channel_state(oldchannel, offer);
+		}
+
+		/* Add the channel back to the array of channels. */
+		vmbus_channel_map_relid(oldchannel);
+		mutex_unlock(&vmbus_connection.channel_mutex);
+		return;
+	}
+
+	/* Allocate the channel object and save this offer. */
+	newchannel = alloc_channel();
+	if (!newchannel) {
+		vmbus_release_relid(offer->child_relid);
+		atomic_dec(&vmbus_connection.offer_in_progress);
+		pr_err("Unable to allocate channel object\n");
+		return;
+	}
+	newchannel->co_ring_buffer = co_ring_buffer;
+	newchannel->co_external_memory = co_external_memory;
+
+	vmbus_setup_channel_state(newchannel, offer);
+
+	vmbus_process_offer(newchannel);
+}
+
+static void check_ready_for_suspend_event(void)
+{
+	/*
+	 * If all the sub-channels or hv_sock channels have been cleaned up,
+	 * then it's safe to suspend.
+	 */
+	if (atomic_dec_and_test(&vmbus_connection.nr_chan_close_on_suspend))
+		complete(&vmbus_connection.ready_for_suspend_event);
+}
+
+/*
+ * vmbus_onoffer_rescind - Rescind offer handler.
+ *
+ * We queue a work item to process this offer synchronously
+ */
+static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_rescind_offer *rescind;
+	struct vmbus_channel *channel;
+	struct device *dev;
+	bool clean_up_chan_for_suspend;
+
+	rescind = (struct vmbus_channel_rescind_offer *)hdr;
+
+	trace_vmbus_onoffer_rescind(rescind);
+
+	/*
+	 * The offer msg and the corresponding rescind msg
+	 * from the host are guranteed to be ordered -
+	 * offer comes in first and then the rescind.
+	 * Since we process these events in work elements,
+	 * and with preemption, we may end up processing
+	 * the events out of order.  We rely on the synchronization
+	 * provided by offer_in_progress and by channel_mutex for
+	 * ordering these events:
+	 *
+	 * { Initially: offer_in_progress = 1 }
+	 *
+	 * CPU1				CPU2
+	 *
+	 * [vmbus_onoffer()]		[vmbus_onoffer_rescind()]
+	 *
+	 * LOCK channel_mutex		WAIT_ON offer_in_progress == 0
+	 * DECREMENT offer_in_progress	LOCK channel_mutex
+	 * STORE channels[]		LOAD channels[]
+	 * UNLOCK channel_mutex		UNLOCK channel_mutex
+	 *
+	 * Forbids: CPU2's LOAD from *not* seeing CPU1's STORE
+	 */
+
+	while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
+		/*
+		 * We wait here until any channel offer is currently
+		 * being processed.
+		 */
+		msleep(1);
+	}
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+	channel = relid2channel(rescind->child_relid);
+	if (channel != NULL) {
+		/*
+		 * Guarantee that no other instance of vmbus_onoffer_rescind()
+		 * has got a reference to the channel object.  Synchronize on
+		 * &vmbus_connection.channel_mutex.
+		 */
+		if (channel->rescind_ref) {
+			mutex_unlock(&vmbus_connection.channel_mutex);
+			return;
+		}
+		channel->rescind_ref = true;
+	}
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	if (channel == NULL) {
+		/*
+		 * We failed in processing the offer message;
+		 * we would have cleaned up the relid in that
+		 * failure path.
+		 */
+		return;
+	}
+
+	clean_up_chan_for_suspend = is_hvsock_channel(channel) ||
+				    is_sub_channel(channel);
+	/*
+	 * Before setting channel->rescind in vmbus_rescind_cleanup(), we
+	 * should make sure the channel callback is not running any more.
+	 */
+	vmbus_reset_channel_cb(channel);
+
+	/*
+	 * Now wait for offer handling to complete.
+	 */
+	vmbus_rescind_cleanup(channel);
+	while (READ_ONCE(channel->probe_done) == false) {
+		/*
+		 * We wait here until any channel offer is currently
+		 * being processed.
+		 */
+		msleep(1);
+	}
+
+	/*
+	 * At this point, the rescind handling can proceed safely.
+	 */
+
+	if (channel->device_obj) {
+		if (channel->chn_rescind_callback) {
+			channel->chn_rescind_callback(channel);
+
+			if (clean_up_chan_for_suspend)
+				check_ready_for_suspend_event();
+
+			return;
+		}
+		/*
+		 * We will have to unregister this device from the
+		 * driver core.
+		 */
+		dev = get_device(&channel->device_obj->device);
+		if (dev) {
+			vmbus_device_unregister(channel->device_obj);
+			put_device(dev);
+		}
+	} else if (channel->primary_channel != NULL) {
+		/*
+		 * Sub-channel is being rescinded. Following is the channel
+		 * close sequence when initiated from the driveri (refer to
+		 * vmbus_close() for details):
+		 * 1. Close all sub-channels first
+		 * 2. Then close the primary channel.
+		 */
+		mutex_lock(&vmbus_connection.channel_mutex);
+		if (channel->state == CHANNEL_OPEN_STATE) {
+			/*
+			 * The channel is currently not open;
+			 * it is safe for us to cleanup the channel.
+			 */
+			hv_process_channel_removal(channel);
+		} else {
+			complete(&channel->rescind_event);
+		}
+		mutex_unlock(&vmbus_connection.channel_mutex);
+	}
+
+	/* The "channel" may have been freed. Do not access it any longer. */
+
+	if (clean_up_chan_for_suspend)
+		check_ready_for_suspend_event();
+}
+
+void vmbus_hvsock_device_unregister(struct vmbus_channel *channel)
+{
+	BUG_ON(!is_hvsock_channel(channel));
+
+	/* We always get a rescind msg when a connection is closed. */
+	while (!READ_ONCE(channel->probe_done) || !READ_ONCE(channel->rescind))
+		msleep(1);
+
+	vmbus_device_unregister(channel->device_obj);
+}
+EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister);
+
+
+/*
+ * vmbus_onoffers_delivered -
+ * The CHANNELMSG_ALLOFFERS_DELIVERED message arrives after all
+ * boot-time offers are delivered. A boot-time offer is for the primary
+ * channel for any virtual hardware configured in the VM at the time it boots.
+ * Boot-time offers include offers for physical devices assigned to the VM
+ * via Hyper-V's Discrete Device Assignment (DDA) functionality that are
+ * handled as virtual PCI devices in Linux (e.g., NVMe devices and GPUs).
+ * Boot-time offers do not include offers for VMBus sub-channels. Because
+ * devices can be hot-added to the VM after it is booted, additional channel
+ * offers that aren't boot-time offers can be received at any time after the
+ * all-offers-delivered message.
+ *
+ * SR-IOV NIC Virtual Functions (VFs) assigned to a VM are not considered
+ * to be assigned to the VM at boot-time, and offers for VFs may occur after
+ * the all-offers-delivered message. VFs are optional accelerators to the
+ * synthetic VMBus NIC and are effectively hot-added only after the VMBus
+ * NIC channel is opened (once it knows the guest can support it, via the
+ * sriov bit in the netvsc protocol).
+ */
+static void vmbus_onoffers_delivered(
+			struct vmbus_channel_message_header *hdr)
+{
+	complete(&vmbus_connection.all_offers_delivered_event);
+}
+
+/*
+ * vmbus_onopen_result - Open result handler.
+ *
+ * This is invoked when we received a response to our channel open request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_open_result *result;
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_open_channel *openmsg;
+	unsigned long flags;
+
+	result = (struct vmbus_channel_open_result *)hdr;
+
+	trace_vmbus_onopen_result(result);
+
+	/*
+	 * Find the open msg, copy the result and signal/unblock the wait event
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
+			openmsg =
+			(struct vmbus_channel_open_channel *)msginfo->msg;
+			if (openmsg->child_relid == result->child_relid &&
+			    openmsg->openid == result->openid) {
+				memcpy(&msginfo->response.open_result,
+				       result,
+				       sizeof(
+					struct vmbus_channel_open_result));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_ongpadl_created - GPADL created handler.
+ *
+ * This is invoked when we received a response to our gpadl create request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_gpadl_created *gpadlcreated;
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_gpadl_header *gpadlheader;
+	unsigned long flags;
+
+	gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
+
+	trace_vmbus_ongpadl_created(gpadlcreated);
+
+	/*
+	 * Find the establish msg, copy the result and signal/unblock the wait
+	 * event
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
+			gpadlheader =
+			(struct vmbus_channel_gpadl_header *)requestheader;
+
+			if ((gpadlcreated->child_relid ==
+			     gpadlheader->child_relid) &&
+			    (gpadlcreated->gpadl == gpadlheader->gpadl)) {
+				memcpy(&msginfo->response.gpadl_created,
+				       gpadlcreated,
+				       sizeof(
+					struct vmbus_channel_gpadl_created));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_onmodifychannel_response - Modify Channel response handler.
+ *
+ * This is invoked when we received a response to our channel modify request.
+ * Find the matching request, copy the response and signal the requesting thread.
+ */
+static void vmbus_onmodifychannel_response(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_modifychannel_response *response;
+	struct vmbus_channel_msginfo *msginfo;
+	unsigned long flags;
+
+	response = (struct vmbus_channel_modifychannel_response *)hdr;
+
+	trace_vmbus_onmodifychannel_response(response);
+
+	/*
+	 * Find the modify msg, copy the response and signal/unblock the wait event.
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list, msglistentry) {
+		struct vmbus_channel_message_header *responseheader =
+				(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (responseheader->msgtype == CHANNELMSG_MODIFYCHANNEL) {
+			struct vmbus_channel_modifychannel *modifymsg;
+
+			modifymsg = (struct vmbus_channel_modifychannel *)msginfo->msg;
+			if (modifymsg->child_relid == response->child_relid) {
+				memcpy(&msginfo->response.modify_response, response,
+				       sizeof(*response));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_ongpadl_torndown - GPADL torndown handler.
+ *
+ * This is invoked when we received a response to our gpadl teardown request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_ongpadl_torndown(
+			struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_gpadl_torndown *gpadl_torndown;
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_gpadl_teardown *gpadl_teardown;
+	unsigned long flags;
+
+	gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
+
+	trace_vmbus_ongpadl_torndown(gpadl_torndown);
+
+	/*
+	 * Find the open msg, copy the result and signal/unblock the wait event
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
+			gpadl_teardown =
+			(struct vmbus_channel_gpadl_teardown *)requestheader;
+
+			if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
+				memcpy(&msginfo->response.gpadl_torndown,
+				       gpadl_torndown,
+				       sizeof(
+					struct vmbus_channel_gpadl_torndown));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_onversion_response - Version response handler
+ *
+ * This is invoked when we received a response to our initiate contact request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_onversion_response(
+		struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_version_response *version_response;
+	unsigned long flags;
+
+	version_response = (struct vmbus_channel_version_response *)hdr;
+
+	trace_vmbus_onversion_response(version_response);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype ==
+		    CHANNELMSG_INITIATE_CONTACT) {
+			memcpy(&msginfo->response.version_response,
+			      version_response,
+			      sizeof(struct vmbus_channel_version_response));
+			complete(&msginfo->waitevent);
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/* Channel message dispatch table */
+const struct vmbus_channel_message_table_entry
+channel_message_table[CHANNELMSG_COUNT] = {
+	{ CHANNELMSG_INVALID,			0, NULL, 0},
+	{ CHANNELMSG_OFFERCHANNEL,		0, vmbus_onoffer,
+		sizeof(struct vmbus_channel_offer_channel)},
+	{ CHANNELMSG_RESCIND_CHANNELOFFER,	0, vmbus_onoffer_rescind,
+		sizeof(struct vmbus_channel_rescind_offer) },
+	{ CHANNELMSG_REQUESTOFFERS,		0, NULL, 0},
+	{ CHANNELMSG_ALLOFFERS_DELIVERED,	1, vmbus_onoffers_delivered, 0},
+	{ CHANNELMSG_OPENCHANNEL,		0, NULL, 0},
+	{ CHANNELMSG_OPENCHANNEL_RESULT,	1, vmbus_onopen_result,
+		sizeof(struct vmbus_channel_open_result)},
+	{ CHANNELMSG_CLOSECHANNEL,		0, NULL, 0},
+	{ CHANNELMSG_GPADL_HEADER,		0, NULL, 0},
+	{ CHANNELMSG_GPADL_BODY,		0, NULL, 0},
+	{ CHANNELMSG_GPADL_CREATED,		1, vmbus_ongpadl_created,
+		sizeof(struct vmbus_channel_gpadl_created)},
+	{ CHANNELMSG_GPADL_TEARDOWN,		0, NULL, 0},
+	{ CHANNELMSG_GPADL_TORNDOWN,		1, vmbus_ongpadl_torndown,
+		sizeof(struct vmbus_channel_gpadl_torndown) },
+	{ CHANNELMSG_RELID_RELEASED,		0, NULL, 0},
+	{ CHANNELMSG_INITIATE_CONTACT,		0, NULL, 0},
+	{ CHANNELMSG_VERSION_RESPONSE,		1, vmbus_onversion_response,
+		sizeof(struct vmbus_channel_version_response)},
+	{ CHANNELMSG_UNLOAD,			0, NULL, 0},
+	{ CHANNELMSG_UNLOAD_RESPONSE,		1, vmbus_unload_response, 0},
+	{ CHANNELMSG_18,			0, NULL, 0},
+	{ CHANNELMSG_19,			0, NULL, 0},
+	{ CHANNELMSG_20,			0, NULL, 0},
+	{ CHANNELMSG_TL_CONNECT_REQUEST,	0, NULL, 0},
+	{ CHANNELMSG_MODIFYCHANNEL,		0, NULL, 0},
+	{ CHANNELMSG_TL_CONNECT_RESULT,		0, NULL, 0},
+	{ CHANNELMSG_MODIFYCHANNEL_RESPONSE,	1, vmbus_onmodifychannel_response,
+		sizeof(struct vmbus_channel_modifychannel_response)},
+};
+
+/*
+ * vmbus_onmessage - Handler for channel protocol messages.
+ *
+ * This is invoked in the vmbus worker thread context.
+ */
+void vmbus_onmessage(struct vmbus_channel_message_header *hdr)
+{
+	trace_vmbus_on_message(hdr);
+
+	/*
+	 * vmbus_on_msg_dpc() makes sure the hdr->msgtype here can not go
+	 * out of bound and the message_handler pointer can not be NULL.
+	 */
+	channel_message_table[hdr->msgtype].message_handler(hdr);
+}
+
+/*
+ * vmbus_request_offers - Send a request to get all our pending offers
+ * and wait for all boot-time offers to arrive.
+ */
+int vmbus_request_offers(void)
+{
+	struct vmbus_channel_message_header *msg;
+	struct vmbus_channel_msginfo *msginfo;
+	int ret;
+
+	msginfo = kzalloc(sizeof(*msginfo) +
+			  sizeof(struct vmbus_channel_message_header),
+			  GFP_KERNEL);
+	if (!msginfo)
+		return -ENOMEM;
+
+	msg = (struct vmbus_channel_message_header *)msginfo->msg;
+
+	msg->msgtype = CHANNELMSG_REQUESTOFFERS;
+
+	/*
+	 * This REQUESTOFFERS message will result in the host sending an all
+	 * offers delivered message after all the boot-time offers are sent.
+	 */
+	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_message_header),
+			     true);
+
+	trace_vmbus_request_offers(ret);
+
+	if (ret != 0) {
+		pr_err("Unable to request offers - %d\n", ret);
+
+		goto cleanup;
+	}
+
+	/*
+	 * Wait for the host to send all boot-time offers.
+	 * Keeping it as a best-effort mechanism, where a warning is
+	 * printed if a timeout occurs, and execution is resumed.
+	 */
+	if (!wait_for_completion_timeout(&vmbus_connection.all_offers_delivered_event,
+					 secs_to_jiffies(60))) {
+		pr_warn("timed out waiting for all boot-time offers to be delivered.\n");
+	}
+
+	/*
+	 * Flush handling of offer messages (which may initiate work on
+	 * other work queues).
+	 */
+	flush_workqueue(vmbus_connection.work_queue);
+
+	/*
+	 * Flush workqueue for processing the incoming offers. Subchannel
+	 * offers and their processing can happen later, so there is no need to
+	 * flush that workqueue here.
+	 */
+	flush_workqueue(vmbus_connection.handle_primary_chan_wq);
+
+cleanup:
+	kfree(msginfo);
+
+	return ret;
+}
+
+void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
+				void (*sc_cr_cb)(struct vmbus_channel *new_sc))
+{
+	primary_channel->sc_creation_callback = sc_cr_cb;
+}
+EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
+
+void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel,
+		void (*chn_rescind_cb)(struct vmbus_channel *))
+{
+	channel->chn_rescind_callback = chn_rescind_cb;
+}
+EXPORT_SYMBOL_GPL(vmbus_set_chn_rescind_callback);
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
new file mode 100644
index 000000000..1ab3581b0
--- /dev/null
+++ b/drivers/hv/connection.c
@@ -0,0 +1,543 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/delay.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/hyperv.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/set_memory.h>
+#include <asm/mshyperv.h>
+
+#include "hyperv_vmbus.h"
+
+
+struct vmbus_connection vmbus_connection = {
+	.conn_state		= DISCONNECTED,
+	.unload_event		= COMPLETION_INITIALIZER(
+				  vmbus_connection.unload_event),
+	.next_gpadl_handle	= ATOMIC_INIT(0xE1E10),
+
+	.ready_for_suspend_event = COMPLETION_INITIALIZER(
+				  vmbus_connection.ready_for_suspend_event),
+	.all_offers_delivered_event = COMPLETION_INITIALIZER(
+				  vmbus_connection.all_offers_delivered_event),
+};
+EXPORT_SYMBOL_GPL(vmbus_connection);
+
+/*
+ * Negotiated protocol version with the host.
+ */
+__u32 vmbus_proto_version;
+EXPORT_SYMBOL_GPL(vmbus_proto_version);
+
+/*
+ * Table of VMBus versions listed from newest to oldest.
+ * VERSION_WIN7,VERSION_WS2008, VERSION_WIN8 (which is
+ * Windows Server 2012) and VERSION_WIN8_1 (which is
+ * Windows Server 2012 R2) are no longer supported in
+ * Linux guests and are not listed.
+ */
+static __u32 vmbus_versions[] = {
+	VERSION_WIN10_V6_0,
+	VERSION_WIN10_V5_3,
+	VERSION_WIN10_V5_2,
+	VERSION_WIN10_V5_1,
+	VERSION_WIN10_V5,
+	VERSION_WIN10_V4_1,
+	VERSION_WIN10
+};
+
+/*
+ * Maximal VMBus protocol version guests can negotiate.  Useful to cap the
+ * VMBus version for testing and debugging purpose.
+ */
+static uint max_version = VERSION_WIN10_V6_0;
+
+module_param(max_version, uint, S_IRUGO);
+MODULE_PARM_DESC(max_version,
+		 "Maximal VMBus protocol version which can be negotiated");
+
+static int vmbus_try_connection_id(struct vmbus_channel_msginfo *msginfo,
+				   u32 version, u32 connection_id)
+{
+	int ret = 0;
+	struct vmbus_channel_initiate_contact *msg;
+	unsigned long flags;
+
+	init_completion(&msginfo->waitevent);
+
+	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
+
+	memset(msg, 0, sizeof(*msg));
+	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
+	msg->vmbus_version_requested = version;
+
+	/*
+	 * For VMBus protocol 5.0 (VERSION_WIN10_V5) and higher, use the
+	 * caller-supplied connection_id for the Initiate Contact message so
+	 * the caller can implement the required retry scheme. For subsequent
+	 * messages, use the Message Connection ID field in the host-returned
+	 * Version Response message. With VERSION_WIN10_V5 and higher, we don't
+	 * use msg->interrupt_page, but tell the host explicitly that we still
+	 * use VMBUS_MESSAGE_SINT(2) for compatibility.
+	 *
+	 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
+	 */
+	if (version >= VERSION_WIN10_V5) {
+		msg->msg_sint = VMBUS_MESSAGE_SINT;
+		msg->msg_vtl = ms_hyperv.vtl;
+		vmbus_connection.msg_conn_id = connection_id;
+	} else {
+		msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
+		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
+	}
+
+	if (vmbus_is_confidential() && version >= VERSION_WIN10_V6_0)
+		msg->feature_flags = VMBUS_FEATURE_FLAG_CONFIDENTIAL_CHANNELS;
+
+	/*
+	 * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
+	 * bitwise OR it
+	 */
+	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
+				ms_hyperv.shared_gpa_boundary;
+	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
+				ms_hyperv.shared_gpa_boundary;
+
+	msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
+
+	/*
+	 * Add to list before we send the request since we may
+	 * receive the response before returning from this routine
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&msginfo->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	ret = vmbus_post_msg(msg,
+			     sizeof(struct vmbus_channel_initiate_contact),
+			     true);
+
+	trace_vmbus_negotiate_version(msg, ret);
+
+	if (ret != 0) {
+		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+		list_del(&msginfo->msglistentry);
+		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
+					flags);
+		return ret;
+	}
+
+	/* Wait for the connection response */
+	wait_for_completion(&msginfo->waitevent);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&msginfo->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	/* Check if successful */
+	if (msginfo->response.version_response.version_supported) {
+		vmbus_connection.conn_state = CONNECTED;
+
+		if (version >= VERSION_WIN10_V5)
+			vmbus_connection.msg_conn_id =
+				msginfo->response.version_response.msg_conn_id;
+	} else {
+		return -ECONNREFUSED;
+	}
+
+	return ret;
+}
+
+int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
+{
+	int ret;
+
+	/* Try the redirect ID first for VTL2 with VMBus protocol 5.0+. */
+	if (version >= VERSION_WIN10_V5 && ms_hyperv.vtl == 2) {
+		ret = vmbus_try_connection_id(msginfo, version,
+					      VMBUS_MESSAGE_CONNECTION_ID_REDIRECT);
+		if (ret != -ENXIO)
+			return ret;
+	}
+
+	return vmbus_try_connection_id(msginfo, version,
+				       VMBUS_MESSAGE_CONNECTION_ID_4);
+}
+
+/*
+ * vmbus_connect - Sends a connect request on the partition service connection
+ */
+int vmbus_connect(void)
+{
+	struct vmbus_channel_msginfo *msginfo = NULL;
+	int i, ret = 0;
+	__u32 version;
+
+	/* Initialize the vmbus connection */
+	vmbus_connection.conn_state = CONNECTING;
+	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
+	if (!vmbus_connection.work_queue) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	vmbus_connection.rescind_work_queue =
+		create_workqueue("hv_vmbus_rescind");
+	if (!vmbus_connection.rescind_work_queue) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+	vmbus_connection.ignore_any_offer_msg = false;
+
+	vmbus_connection.handle_primary_chan_wq =
+		create_workqueue("hv_pri_chan");
+	if (!vmbus_connection.handle_primary_chan_wq) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	vmbus_connection.handle_sub_chan_wq =
+		create_workqueue("hv_sub_chan");
+	if (!vmbus_connection.handle_sub_chan_wq) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
+	spin_lock_init(&vmbus_connection.channelmsg_lock);
+
+	INIT_LIST_HEAD(&vmbus_connection.chn_list);
+	mutex_init(&vmbus_connection.channel_mutex);
+
+	/*
+	 * The following Hyper-V interrupt and monitor pages can be used by
+	 * UIO for mapping to user-space, so they should always be allocated on
+	 * system page boundaries. The system page size must be >= the Hyper-V
+	 * page size.
+	 */
+	BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
+
+	/*
+	 * Setup the vmbus event connection for channel interrupt
+	 * abstraction stuff
+	 */
+	vmbus_connection.int_page =
+		(void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	if (vmbus_connection.int_page == NULL) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	vmbus_connection.recv_int_page = vmbus_connection.int_page;
+	vmbus_connection.send_int_page =
+		(void *)((unsigned long)vmbus_connection.int_page +
+			(HV_HYP_PAGE_SIZE >> 1));
+
+	/*
+	 * Setup the monitor notification facility. The 1st page for
+	 * parent->child and the 2nd page for child->parent
+	 */
+	vmbus_connection.monitor_pages[0] = (void *)__get_free_page(GFP_KERNEL);
+	vmbus_connection.monitor_pages[1] = (void *)__get_free_page(GFP_KERNEL);
+	if ((vmbus_connection.monitor_pages[0] == NULL) ||
+	    (vmbus_connection.monitor_pages[1] == NULL)) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	ret = set_memory_decrypted((unsigned long)
+				vmbus_connection.monitor_pages[0], 1);
+	ret |= set_memory_decrypted((unsigned long)
+				vmbus_connection.monitor_pages[1], 1);
+	if (ret) {
+		/*
+		 * If set_memory_decrypted() fails, the encryption state
+		 * of the memory is unknown. So leak the memory instead
+		 * of risking returning decrypted memory to the free list.
+		 * For simplicity, always handle both pages the same.
+		 */
+		vmbus_connection.monitor_pages[0] = NULL;
+		vmbus_connection.monitor_pages[1] = NULL;
+		goto cleanup;
+	}
+
+	/*
+	 * Set_memory_decrypted() will change the memory contents if
+	 * decryption occurs, so zero monitor pages here.
+	 */
+	memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
+	memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);
+
+	msginfo = kzalloc(sizeof(*msginfo) +
+			  sizeof(struct vmbus_channel_initiate_contact),
+			  GFP_KERNEL);
+	if (msginfo == NULL) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	/*
+	 * Negotiate a compatible VMBUS version number with the
+	 * host. We start with the highest number we can support
+	 * and work our way down until we negotiate a compatible
+	 * version.
+	 */
+
+	for (i = 0; ; i++) {
+		if (i == ARRAY_SIZE(vmbus_versions)) {
+			ret = -EDOM;
+			pr_err("Hyper-V host does not support VMBus version %d.%d or higher;\n\
+		 the host may be an older version no longer supported by Linux\n",
+				vmbus_versions[i-1] >> 16, vmbus_versions[i-1] & 0xFFFF);
+			goto cleanup;
+		}
+
+		version = vmbus_versions[i];
+		if (version > max_version)
+			continue;
+
+		ret = vmbus_negotiate_version(msginfo, version);
+		if (ret == -ETIMEDOUT)
+			goto cleanup;
+
+		if (vmbus_connection.conn_state == CONNECTED)
+			break;
+	}
+
+	if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
+		pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
+		       version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
+		ret = -EINVAL;
+		goto cleanup;
+	}
+
+	vmbus_proto_version = version;
+	pr_info("Vmbus version:%d.%d\n",
+		version >> 16, version & 0xFFFF);
+
+	vmbus_connection.channels = kzalloc_objs(struct vmbus_channel *,
+						 MAX_CHANNEL_RELIDS);
+	if (vmbus_connection.channels == NULL) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	kfree(msginfo);
+	return 0;
+
+cleanup:
+	pr_err("Unable to connect to host\n");
+
+	vmbus_connection.conn_state = DISCONNECTED;
+	vmbus_disconnect();
+
+	kfree(msginfo);
+
+	return ret;
+}
+
+void vmbus_disconnect(void)
+{
+	/*
+	 * First send the unload request to the host.
+	 */
+	vmbus_initiate_unload(false);
+
+	if (vmbus_connection.handle_sub_chan_wq)
+		destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
+
+	if (vmbus_connection.handle_primary_chan_wq)
+		destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
+
+	if (vmbus_connection.rescind_work_queue)
+		destroy_workqueue(vmbus_connection.rescind_work_queue);
+
+	if (vmbus_connection.work_queue)
+		destroy_workqueue(vmbus_connection.work_queue);
+
+	if (vmbus_connection.int_page) {
+		free_page((unsigned long)vmbus_connection.int_page);
+		vmbus_connection.int_page = NULL;
+	}
+
+	if (vmbus_connection.monitor_pages[0]) {
+		if (!set_memory_encrypted(
+			(unsigned long)vmbus_connection.monitor_pages[0], 1))
+			free_page((unsigned long)
+				vmbus_connection.monitor_pages[0]);
+		vmbus_connection.monitor_pages[0] = NULL;
+	}
+
+	if (vmbus_connection.monitor_pages[1]) {
+		if (!set_memory_encrypted(
+			(unsigned long)vmbus_connection.monitor_pages[1], 1))
+			free_page((unsigned long)
+				vmbus_connection.monitor_pages[1]);
+		vmbus_connection.monitor_pages[1] = NULL;
+	}
+}
+
+/*
+ * relid2channel - Get the channel object given its
+ * child relative id (ie channel id)
+ */
+struct vmbus_channel *relid2channel(u32 relid)
+{
+	if (vmbus_connection.channels == NULL) {
+		pr_warn_once("relid2channel: relid=%d: No channels mapped!\n", relid);
+		return NULL;
+	}
+	if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
+		return NULL;
+	return READ_ONCE(vmbus_connection.channels[relid]);
+}
+
+/*
+ * vmbus_on_event - Process a channel event notification
+ *
+ * For batched channels (default) optimize host to guest signaling
+ * by ensuring:
+ * 1. While reading the channel, we disable interrupts from host.
+ * 2. Ensure that we process all posted messages from the host
+ *    before returning from this callback.
+ * 3. Once we return, enable signaling from the host. Once this
+ *    state is set we check to see if additional packets are
+ *    available to read. In this case we repeat the process.
+ *    If this tasklet has been running for a long time
+ *    then reschedule ourselves.
+ */
+void vmbus_on_event(unsigned long data)
+{
+	struct vmbus_channel *channel = (void *) data;
+	void (*callback_fn)(void *context);
+
+	trace_vmbus_on_event(channel);
+
+	hv_debug_delay_test(channel, INTERRUPT_DELAY);
+
+	/* A channel once created is persistent even when
+	 * there is no driver handling the device. An
+	 * unloading driver sets the onchannel_callback to NULL.
+	 */
+	callback_fn = READ_ONCE(channel->onchannel_callback);
+	if (unlikely(!callback_fn))
+		return;
+
+	(*callback_fn)(channel->channel_callback_context);
+
+	if (channel->callback_mode != HV_CALL_BATCHED)
+		return;
+
+	if (likely(hv_end_read(&channel->inbound) == 0))
+		return;
+
+	hv_begin_read(&channel->inbound);
+	tasklet_schedule(&channel->callback_event);
+}
+
+/*
+ * vmbus_post_msg - Send a msg on the vmbus's message connection
+ */
+int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
+{
+	struct vmbus_channel_message_header *hdr;
+	union hv_connection_id conn_id;
+	int ret = 0;
+	int retries = 0;
+	u32 usec = 1;
+
+	conn_id.asu32 = 0;
+	conn_id.u.id = vmbus_connection.msg_conn_id;
+
+	/*
+	 * hv_post_message() can have transient failures because of
+	 * insufficient resources. Retry the operation a couple of
+	 * times before giving up.
+	 */
+	while (retries < 100) {
+		ret = hv_post_message(conn_id, 1, buffer, buflen);
+
+		switch (ret) {
+		case HV_STATUS_INVALID_CONNECTION_ID:
+			/* Allow INITIATE_CONTACT to try another connection ID. */
+			hdr = buffer;
+			if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
+				return -ENXIO;
+			/*
+			 * We could get this if we send messages too
+			 * frequently.
+			 */
+			ret = -EAGAIN;
+			break;
+		case HV_STATUS_INSUFFICIENT_MEMORY:
+		case HV_STATUS_INSUFFICIENT_BUFFERS:
+			ret = -ENOBUFS;
+			break;
+		case HV_STATUS_SUCCESS:
+			return ret;
+		default:
+			pr_err("hv_post_msg() failed; error code:%d\n", ret);
+			return -EINVAL;
+		}
+
+		retries++;
+		if (can_sleep && usec > 1000)
+			msleep(usec / 1000);
+		else if (usec < MAX_UDELAY_MS * 1000)
+			udelay(usec);
+		else
+			mdelay(usec / 1000);
+
+		if (retries < 22)
+			usec *= 2;
+	}
+	return ret;
+}
+
+/*
+ * vmbus_set_event - Send an event notification to the parent
+ */
+void vmbus_set_event(struct vmbus_channel *channel)
+{
+	u32 child_relid = channel->offermsg.child_relid;
+
+	if (!channel->is_dedicated_interrupt)
+		vmbus_send_interrupt(child_relid);
+
+	++channel->sig_events;
+
+	if (ms_hyperv.paravisor_present) {
+		if (hv_isolation_type_snp())
+			hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
+					  NULL, sizeof(channel->sig_event));
+		else if (hv_isolation_type_tdx())
+			hv_tdx_hypercall(HVCALL_SIGNAL_EVENT | HV_HYPERCALL_FAST_BIT,
+					 channel->sig_event, 0);
+		else
+			WARN_ON_ONCE(1);
+	} else {
+		u64 control = HVCALL_SIGNAL_EVENT;
+
+		control |= hv_nested ? HV_HYPERCALL_NESTED : 0;
+		hv_do_fast_hypercall8(control, channel->sig_event);
+	}
+}
+EXPORT_SYMBOL_GPL(vmbus_set_event);
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
new file mode 100644
index 000000000..fe50090dc
--- /dev/null
+++ b/drivers/hv/hv.c
@@ -0,0 +1,654 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/hyperv.h>
+#include <linux/random.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/export.h>
+#include <clocksource/hyperv_timer.h>
+#include <asm/mshyperv.h>
+#include <linux/set_memory.h>
+#include "hyperv_vmbus.h"
+
+/* The one and only */
+struct hv_context hv_context;
+EXPORT_SYMBOL_FOR_MODULES(hv_context, "mshv_vtl");
+
+/*
+ * hv_init - Main initialization routine.
+ *
+ * This routine must be called before any other routines in here are called
+ */
+int hv_init(void)
+{
+	hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
+	if (!hv_context.cpu_context)
+		return -ENOMEM;
+	return 0;
+}
+
+/*
+ * hv_post_message - Post a message using the hypervisor message IPC.
+ *
+ * This involves a hypercall.
+ */
+int hv_post_message(union hv_connection_id connection_id,
+			enum hv_message_type message_type,
+			void *payload, size_t payload_size)
+{
+	struct hv_input_post_message *aligned_msg;
+	unsigned long flags;
+	u64 status;
+
+	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
+		return -EMSGSIZE;
+
+	local_irq_save(flags);
+
+	/*
+	 * A TDX VM with the paravisor must use the decrypted post_msg_page: see
+	 * the comment in struct hv_per_cpu_context. A SNP VM with the paravisor
+	 * can use the encrypted hyperv_pcpu_input_arg because it copies the
+	 * input into the GHCB page, which has been decrypted by the paravisor.
+	 */
+	if (hv_isolation_type_tdx() && ms_hyperv.paravisor_present)
+		aligned_msg = this_cpu_ptr(hv_context.cpu_context)->post_msg_page;
+	else
+		aligned_msg = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	aligned_msg->connectionid = connection_id;
+	aligned_msg->reserved = 0;
+	aligned_msg->message_type = message_type;
+	aligned_msg->payload_size = payload_size;
+	memcpy((void *)aligned_msg->payload, payload, payload_size);
+
+	if (ms_hyperv.paravisor_present && !vmbus_is_confidential()) {
+		/*
+		 * If the VMBus isn't confidential, use the CoCo-specific
+		 * mechanism to communicate with the hypervisor.
+		 */
+		if (hv_isolation_type_tdx())
+			status = hv_tdx_hypercall(HVCALL_POST_MESSAGE,
+						  virt_to_phys(aligned_msg), 0);
+		else if (hv_isolation_type_snp())
+			status = hv_ghcb_hypercall(HVCALL_POST_MESSAGE,
+						   aligned_msg, NULL,
+						   sizeof(*aligned_msg));
+		else
+			status = HV_STATUS_INVALID_PARAMETER;
+	} else {
+		u64 control = HVCALL_POST_MESSAGE;
+
+		control |= hv_nested ? HV_HYPERCALL_NESTED : 0;
+		/*
+		 * If there is no paravisor, this will go to the hypervisor.
+		 * In the Confidential VMBus case, there is the paravisor
+		 * to which this will trap.
+		 */
+		status = hv_do_hypercall(control, aligned_msg, NULL);
+	}
+
+	local_irq_restore(flags);
+
+	return hv_result(status);
+}
+EXPORT_SYMBOL_FOR_MODULES(hv_post_message, "mshv_vtl");
+
+static int hv_alloc_page(void **page, bool decrypt, const char *note)
+{
+	int ret = 0;
+
+	/*
+	 * After the page changes its encryption status, its contents might
+	 * appear scrambled on some hardware. Thus `get_zeroed_page` would
+	 * zero the page out in vain, so do that explicitly exactly once.
+	 *
+	 * By default, the page is allocated encrypted in a CoCo VM.
+	 */
+	*page = (void *)__get_free_page(GFP_KERNEL);
+	if (!*page)
+		return -ENOMEM;
+
+	if (decrypt)
+		ret = set_memory_decrypted((unsigned long)*page, 1);
+	if (ret)
+		goto failed;
+
+	memset(*page, 0, PAGE_SIZE);
+	return 0;
+
+failed:
+	/*
+	 * Report the failure but don't put the page back on the free list as
+	 * its encryption status is unknown.
+	 */
+	pr_err("allocation failed for %s page, error %d, decrypted %d\n",
+		note, ret, decrypt);
+	*page = NULL;
+	return ret;
+}
+
+static int hv_free_page(void **page, bool encrypt, const char *note)
+{
+	int ret = 0;
+
+	if (!*page)
+		return 0;
+
+	if (encrypt)
+		ret = set_memory_encrypted((unsigned long)*page, 1);
+
+	/*
+	 * In the case of the failure, the page is leaked. Something is wrong,
+	 * prefer to lose the page with the unknown encryption status and stay afloat.
+	 */
+	if (ret)
+		pr_err("deallocation failed for %s page, error %d, encrypt %d\n",
+			note, ret, encrypt);
+	else
+		free_page((unsigned long)*page);
+
+	*page = NULL;
+
+	return ret;
+}
+
+int hv_synic_alloc(void)
+{
+	int cpu, ret = -ENOMEM;
+	struct hv_per_cpu_context *hv_cpu;
+	const bool decrypt = !vmbus_is_confidential();
+
+	/*
+	 * First, zero all per-cpu memory areas so hv_synic_free() can
+	 * detect what memory has been allocated and cleanup properly
+	 * after any failures.
+	 */
+	for_each_present_cpu(cpu) {
+		hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
+		memset(hv_cpu, 0, sizeof(*hv_cpu));
+	}
+
+	hv_context.hv_numa_map = kzalloc_objs(struct cpumask, nr_node_ids);
+	if (!hv_context.hv_numa_map) {
+		pr_err("Unable to allocate NUMA map\n");
+		goto err;
+	}
+
+	for_each_present_cpu(cpu) {
+		hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
+
+		tasklet_init(&hv_cpu->msg_dpc,
+			     vmbus_on_msg_dpc, (unsigned long)hv_cpu);
+
+		if (ms_hyperv.paravisor_present && hv_isolation_type_tdx()) {
+			ret = hv_alloc_page(&hv_cpu->post_msg_page,
+				decrypt, "post msg");
+			if (ret)
+				goto err;
+		}
+
+		/*
+		 * If these SynIC pages are not allocated, SIEF and SIM pages
+		 * are configured using what the root partition or the paravisor
+		 * provides upon reading the SIEFP and SIMP registers.
+		 */
+		if (!ms_hyperv.paravisor_present && !hv_root_partition()) {
+			ret = hv_alloc_page(&hv_cpu->hyp_synic_message_page,
+				decrypt, "hypervisor SynIC msg");
+			if (ret)
+				goto err;
+			ret = hv_alloc_page(&hv_cpu->hyp_synic_event_page,
+				decrypt, "hypervisor SynIC event");
+			if (ret)
+				goto err;
+		}
+
+		if (vmbus_is_confidential()) {
+			ret = hv_alloc_page(&hv_cpu->para_synic_message_page,
+				false, "paravisor SynIC msg");
+			if (ret)
+				goto err;
+			ret = hv_alloc_page(&hv_cpu->para_synic_event_page,
+				false, "paravisor SynIC event");
+			if (ret)
+				goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	/*
+	 * Any memory allocations that succeeded will be freed when
+	 * the caller cleans up by calling hv_synic_free()
+	 */
+	return ret;
+}
+
+void hv_synic_free(void)
+{
+	int cpu;
+	const bool encrypt = !vmbus_is_confidential();
+
+	for_each_present_cpu(cpu) {
+		struct hv_per_cpu_context *hv_cpu =
+			per_cpu_ptr(hv_context.cpu_context, cpu);
+
+		if (ms_hyperv.paravisor_present && hv_isolation_type_tdx())
+			hv_free_page(&hv_cpu->post_msg_page,
+				encrypt, "post msg");
+		if (!ms_hyperv.paravisor_present && !hv_root_partition()) {
+			hv_free_page(&hv_cpu->hyp_synic_event_page,
+				encrypt, "hypervisor SynIC event");
+			hv_free_page(&hv_cpu->hyp_synic_message_page,
+				encrypt, "hypervisor SynIC msg");
+		}
+		if (vmbus_is_confidential()) {
+			hv_free_page(&hv_cpu->para_synic_event_page,
+				false, "paravisor SynIC event");
+			hv_free_page(&hv_cpu->para_synic_message_page,
+				false, "paravisor SynIC msg");
+		}
+	}
+
+	kfree(hv_context.hv_numa_map);
+}
+
+/*
+ * hv_hyp_synic_enable_regs - Initialize the Synthetic Interrupt Controller
+ * with the hypervisor.
+ *
+ * Note: When MSHV is present, mshv_synic_cpu_init() intializes further
+ * registers later.
+ */
+void hv_hyp_synic_enable_regs(unsigned int cpu)
+{
+	struct hv_per_cpu_context *hv_cpu =
+		per_cpu_ptr(hv_context.cpu_context, cpu);
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+	union hv_synic_sint shared_sint;
+
+	/* Setup the Synic's message page with the hypervisor. */
+	simp.as_uint64 = hv_get_msr(HV_MSR_SIMP);
+	simp.simp_enabled = 1;
+
+	if (ms_hyperv.paravisor_present || hv_root_partition()) {
+		/* Mask out vTOM bit and map as decrypted */
+		u64 base = (simp.base_simp_gpa << HV_HYP_PAGE_SHIFT) &
+				~ms_hyperv.shared_gpa_boundary;
+		hv_cpu->hyp_synic_message_page =
+			memremap(base, HV_HYP_PAGE_SIZE, MEMREMAP_WB | MEMREMAP_DEC);
+		if (!hv_cpu->hyp_synic_message_page)
+			pr_err("Fail to map synic message page.\n");
+	} else {
+		simp.base_simp_gpa = virt_to_phys(hv_cpu->hyp_synic_message_page)
+			>> HV_HYP_PAGE_SHIFT;
+	}
+
+	hv_set_msr(HV_MSR_SIMP, simp.as_uint64);
+
+	/* Setup the Synic's event page with the hypervisor. */
+	siefp.as_uint64 = hv_get_msr(HV_MSR_SIEFP);
+	siefp.siefp_enabled = 1;
+
+	if (ms_hyperv.paravisor_present || hv_root_partition()) {
+		/* Mask out vTOM bit and map as decrypted */
+		u64 base = (siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT) &
+				~ms_hyperv.shared_gpa_boundary;
+		hv_cpu->hyp_synic_event_page =
+			memremap(base, HV_HYP_PAGE_SIZE, MEMREMAP_WB | MEMREMAP_DEC);
+		if (!hv_cpu->hyp_synic_event_page)
+			pr_err("Fail to map synic event page.\n");
+	} else {
+		siefp.base_siefp_gpa = virt_to_phys(hv_cpu->hyp_synic_event_page)
+			>> HV_HYP_PAGE_SHIFT;
+	}
+
+	hv_set_msr(HV_MSR_SIEFP, siefp.as_uint64);
+	hv_enable_coco_interrupt(cpu, vmbus_interrupt, true);
+
+	/* Setup the shared SINT. */
+	if (vmbus_irq != -1)
+		enable_percpu_irq(vmbus_irq, 0);
+	shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
+
+	shared_sint.vector = vmbus_interrupt;
+	shared_sint.masked = false;
+	shared_sint.auto_eoi = hv_recommend_using_aeoi();
+	hv_set_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+}
+
+static void hv_hyp_synic_enable_interrupts(void)
+{
+	union hv_synic_scontrol sctrl;
+
+	/* Enable the global synic bit */
+	sctrl.as_uint64 = hv_get_msr(HV_MSR_SCONTROL);
+	sctrl.enable = 1;
+
+	hv_set_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
+}
+
+static void hv_para_synic_enable_regs(unsigned int cpu)
+{
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+	struct hv_per_cpu_context *hv_cpu
+		= per_cpu_ptr(hv_context.cpu_context, cpu);
+
+	/* Setup the Synic's message page with the paravisor. */
+	simp.as_uint64 = hv_para_get_synic_register(HV_MSR_SIMP);
+	simp.simp_enabled = 1;
+	simp.base_simp_gpa = virt_to_phys(hv_cpu->para_synic_message_page)
+			>> HV_HYP_PAGE_SHIFT;
+	hv_para_set_synic_register(HV_MSR_SIMP, simp.as_uint64);
+
+	/* Setup the Synic's event page with the paravisor. */
+	siefp.as_uint64 = hv_para_get_synic_register(HV_MSR_SIEFP);
+	siefp.siefp_enabled = 1;
+	siefp.base_siefp_gpa = virt_to_phys(hv_cpu->para_synic_event_page)
+			>> HV_HYP_PAGE_SHIFT;
+	hv_para_set_synic_register(HV_MSR_SIEFP, siefp.as_uint64);
+}
+
+static void hv_para_synic_enable_interrupts(void)
+{
+	union hv_synic_scontrol sctrl;
+
+	/* Enable the global synic bit */
+	sctrl.as_uint64 = hv_para_get_synic_register(HV_MSR_SCONTROL);
+	sctrl.enable = 1;
+	hv_para_set_synic_register(HV_MSR_SCONTROL, sctrl.as_uint64);
+}
+
+int hv_synic_init(unsigned int cpu)
+{
+	if (vmbus_is_confidential())
+		hv_para_synic_enable_regs(cpu);
+
+	/*
+	 * The SINT is set in hv_hyp_synic_enable_regs() by calling
+	 * hv_set_msr(). hv_set_msr() in turn has special case code for the
+	 * SINT MSRs that write to the hypervisor version of the MSR *and*
+	 * the paravisor version of the MSR (but *without* the proxy bit when
+	 * VMBus is confidential).
+	 *
+	 * Then enable interrupts via the paravisor if VMBus is confidential,
+	 * and otherwise via the hypervisor.
+	 */
+
+	hv_hyp_synic_enable_regs(cpu);
+	if (vmbus_is_confidential())
+		hv_para_synic_enable_interrupts();
+	else
+		hv_hyp_synic_enable_interrupts();
+
+	return 0;
+}
+
+void hv_hyp_synic_disable_regs(unsigned int cpu)
+{
+	struct hv_per_cpu_context *hv_cpu =
+		per_cpu_ptr(hv_context.cpu_context, cpu);
+	union hv_synic_sint shared_sint;
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+
+	shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
+
+	shared_sint.masked = 1;
+
+	/* Need to correctly cleanup in the case of SMP!!! */
+	/* Disable the interrupt */
+	hv_set_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+	hv_enable_coco_interrupt(cpu, vmbus_interrupt, false);
+
+	simp.as_uint64 = hv_get_msr(HV_MSR_SIMP);
+	/*
+	 * In Isolation VM, simp and sief pages are allocated by
+	 * paravisor. These pages also will be used by kdump
+	 * kernel. So just reset enable bit here and keep page
+	 * addresses.
+	 */
+	simp.simp_enabled = 0;
+	if (ms_hyperv.paravisor_present || hv_root_partition()) {
+		if (hv_cpu->hyp_synic_message_page) {
+			memunmap(hv_cpu->hyp_synic_message_page);
+			hv_cpu->hyp_synic_message_page = NULL;
+		}
+	} else {
+		simp.base_simp_gpa = 0;
+	}
+
+	hv_set_msr(HV_MSR_SIMP, simp.as_uint64);
+
+	siefp.as_uint64 = hv_get_msr(HV_MSR_SIEFP);
+	siefp.siefp_enabled = 0;
+
+	if (ms_hyperv.paravisor_present || hv_root_partition()) {
+		if (hv_cpu->hyp_synic_event_page) {
+			memunmap(hv_cpu->hyp_synic_event_page);
+			hv_cpu->hyp_synic_event_page = NULL;
+		}
+	} else {
+		siefp.base_siefp_gpa = 0;
+	}
+
+	hv_set_msr(HV_MSR_SIEFP, siefp.as_uint64);
+}
+
+static void hv_hyp_synic_disable_interrupts(void)
+{
+	union hv_synic_scontrol sctrl;
+
+	/* Disable the global synic bit */
+	sctrl.as_uint64 = hv_get_msr(HV_MSR_SCONTROL);
+	sctrl.enable = 0;
+	hv_set_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
+}
+
+static void hv_para_synic_disable_regs(unsigned int cpu)
+{
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+
+	/* Disable SynIC's message page in the paravisor. */
+	simp.as_uint64 = hv_para_get_synic_register(HV_MSR_SIMP);
+	simp.simp_enabled = 0;
+	hv_para_set_synic_register(HV_MSR_SIMP, simp.as_uint64);
+
+	/* Disable SynIC's event page in the paravisor. */
+	siefp.as_uint64 = hv_para_get_synic_register(HV_MSR_SIEFP);
+	siefp.siefp_enabled = 0;
+	hv_para_set_synic_register(HV_MSR_SIEFP, siefp.as_uint64);
+}
+
+static void hv_para_synic_disable_interrupts(void)
+{
+	union hv_synic_scontrol sctrl;
+
+	/* Disable the global synic bit */
+	sctrl.as_uint64 = hv_para_get_synic_register(HV_MSR_SCONTROL);
+	sctrl.enable = 0;
+	hv_para_set_synic_register(HV_MSR_SCONTROL, sctrl.as_uint64);
+}
+
+#define HV_MAX_TRIES 3
+/*
+ * Scan the event flags page of 'this' CPU looking for any bit that is set.  If we find one
+ * bit set, then wait for a few milliseconds.  Repeat these steps for a maximum of 3 times.
+ * Return 'true', if there is still any set bit after this operation; 'false', otherwise.
+ *
+ * If a bit is set, that means there is a pending channel interrupt.  The expectation is
+ * that the normal interrupt handling mechanism will find and process the channel interrupt
+ * "very soon", and in the process clear the bit.
+ */
+static bool __hv_synic_event_pending(union hv_synic_event_flags *event, int sint)
+{
+	unsigned long *recv_int_page;
+	bool pending;
+	u32 relid;
+	int tries = 0;
+
+	if (!event)
+		return false;
+
+	event += sint;
+	recv_int_page = event->flags; /* assumes VMBus version >= VERSION_WIN8 */
+retry:
+	pending = false;
+	for_each_set_bit(relid, recv_int_page, HV_EVENT_FLAGS_COUNT) {
+		/* Special case - VMBus channel protocol messages */
+		if (relid == 0)
+			continue;
+		pending = true;
+		break;
+	}
+	if (pending && tries++ < HV_MAX_TRIES) {
+		usleep_range(10000, 20000);
+		goto retry;
+	}
+	return pending;
+}
+
+static bool hv_synic_event_pending(void)
+{
+	struct hv_per_cpu_context *hv_cpu = this_cpu_ptr(hv_context.cpu_context);
+	union hv_synic_event_flags *hyp_synic_event_page = hv_cpu->hyp_synic_event_page;
+	union hv_synic_event_flags *para_synic_event_page = hv_cpu->para_synic_event_page;
+
+	return
+		__hv_synic_event_pending(hyp_synic_event_page, VMBUS_MESSAGE_SINT) ||
+		__hv_synic_event_pending(para_synic_event_page, VMBUS_MESSAGE_SINT);
+}
+
+static int hv_pick_new_cpu(struct vmbus_channel *channel)
+{
+	int ret = -EBUSY;
+	int start;
+	int cpu;
+
+	lockdep_assert_cpus_held();
+	lockdep_assert_held(&vmbus_connection.channel_mutex);
+
+	/*
+	 * We can't assume that the relevant interrupts will be sent before
+	 * the cpu is offlined on older versions of hyperv.
+	 */
+	if (vmbus_proto_version < VERSION_WIN10_V5_3)
+		return -EBUSY;
+
+	start = get_random_u32_below(nr_cpu_ids);
+
+	for_each_cpu_wrap(cpu, cpu_online_mask, start) {
+		if (channel->target_cpu == cpu ||
+		    channel->target_cpu == VMBUS_CONNECT_CPU)
+			continue;
+
+		ret = vmbus_channel_set_cpu(channel, cpu);
+		if (!ret)
+			break;
+	}
+
+	if (ret)
+		ret = vmbus_channel_set_cpu(channel, VMBUS_CONNECT_CPU);
+
+	return ret;
+}
+
+/*
+ * hv_synic_cleanup - Cleanup routine for hv_synic_init().
+ */
+int hv_synic_cleanup(unsigned int cpu)
+{
+	struct vmbus_channel *channel, *sc;
+	int ret = 0;
+
+	if (vmbus_connection.conn_state != CONNECTED)
+		goto always_cleanup;
+
+	/*
+	 * Hyper-V does not provide a way to change the connect CPU once
+	 * it is set; we must prevent the connect CPU from going offline
+	 * while the VM is running normally. But in the panic or kexec()
+	 * path where the vmbus is already disconnected, the CPU must be
+	 * allowed to shut down.
+	 */
+	if (cpu == VMBUS_CONNECT_CPU)
+		return -EBUSY;
+
+	/*
+	 * Search for channels which are bound to the CPU we're about to
+	 * cleanup.
+	 */
+	mutex_lock(&vmbus_connection.channel_mutex);
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (channel->target_cpu == cpu) {
+			ret = hv_pick_new_cpu(channel);
+			if (ret) {
+				mutex_unlock(&vmbus_connection.channel_mutex);
+				return ret;
+			}
+		}
+		list_for_each_entry(sc, &channel->sc_list, sc_list) {
+			if (sc->target_cpu == cpu) {
+				ret = hv_pick_new_cpu(sc);
+				if (ret) {
+					mutex_unlock(&vmbus_connection.channel_mutex);
+					return ret;
+				}
+			}
+		}
+	}
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	/*
+	 * Scan the event flags page looking for bits that are set and waiting
+	 * with a timeout for vmbus_chan_sched() to process such bits. If bits
+	 * are still set after this operation and VMBus is connected, fail the
+	 * CPU offlining operation.
+	 */
+	if (vmbus_proto_version >= VERSION_WIN10_V4_1 && hv_synic_event_pending())
+		return -EBUSY;
+
+always_cleanup:
+	/*
+	 * First, disable the event and message pages
+	 * used for communicating with the host, and then
+	 * disable the host interrupts if VMBus is not
+	 * confidential.
+	 */
+	hv_hyp_synic_disable_regs(cpu);
+	if (!vmbus_is_confidential())
+		hv_hyp_synic_disable_interrupts();
+
+	/*
+	 * Perform the same steps for the Confidential VMBus.
+	 * The sequencing provides the guarantee that no data
+	 * may be posted for processing before disabling interrupts.
+	 */
+	if (vmbus_is_confidential()) {
+		hv_para_synic_disable_regs(cpu);
+		hv_para_synic_disable_interrupts();
+	}
+	if (vmbus_irq != -1)
+		disable_percpu_irq(vmbus_irq);
+
+	return ret;
+}
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
new file mode 100644
index 000000000..39c1b793a
--- /dev/null
+++ b/drivers/hv/hv_balloon.c
@@ -0,0 +1,2132 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012, Microsoft Corporation.
+ *
+ * Author:
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cleanup.h>
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/mman.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/completion.h>
+#include <linux/count_zeros.h>
+#include <linux/memory_hotplug.h>
+#include <linux/memory.h>
+#include <linux/notifier.h>
+#include <linux/percpu_counter.h>
+#include <linux/page_reporting.h>
+#include <linux/sizes.h>
+
+#include <linux/hyperv.h>
+#include <hyperv/hvhdk.h>
+
+#include <asm/mshyperv.h>
+
+#define CREATE_TRACE_POINTS
+#include "hv_trace_balloon.h"
+
+/*
+ * We begin with definitions supporting the Dynamic Memory protocol
+ * with the host.
+ *
+ * Begin protocol definitions.
+ */
+
+/*
+ * Protocol versions. The low word is the minor version, the high word the major
+ * version.
+ *
+ * History:
+ * Initial version 1.0
+ * Changed to 0.1 on 2009/03/25
+ * Changes to 0.2 on 2009/05/14
+ * Changes to 0.3 on 2009/12/03
+ * Changed to 1.0 on 2011/04/05
+ */
+
+#define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
+#define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
+#define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)
+
+/*
+ * VERSION_1 and VERSION_2 are retained for the historical record,
+ * but are no longer supported in Linux guests.
+ */
+enum {
+	DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
+	DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
+	DYNMEM_PROTOCOL_VERSION_3 = DYNMEM_MAKE_VERSION(2, 0),
+
+	DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
+	DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
+	DYNMEM_PROTOCOL_VERSION_WIN10 = DYNMEM_PROTOCOL_VERSION_3
+};
+
+/*
+ * Message Types
+ */
+
+enum dm_message_type {
+	/*
+	 * Version 0.3
+	 */
+	DM_ERROR			= 0,
+	DM_VERSION_REQUEST		= 1,
+	DM_VERSION_RESPONSE		= 2,
+	DM_CAPABILITIES_REPORT		= 3,
+	DM_CAPABILITIES_RESPONSE	= 4,
+	DM_STATUS_REPORT		= 5,
+	DM_BALLOON_REQUEST		= 6,
+	DM_BALLOON_RESPONSE		= 7,
+	DM_UNBALLOON_REQUEST		= 8,
+	DM_UNBALLOON_RESPONSE		= 9,
+	DM_MEM_HOT_ADD_REQUEST		= 10,
+	DM_MEM_HOT_ADD_RESPONSE		= 11,
+	DM_VERSION_03_MAX		= 11,
+	/*
+	 * Version 1.0.
+	 */
+	DM_INFO_MESSAGE			= 12,
+	DM_VERSION_1_MAX		= 12
+};
+
+/*
+ * Structures defining the dynamic memory management
+ * protocol.
+ */
+
+union dm_version {
+	struct {
+		__u16 minor_version;
+		__u16 major_version;
+	};
+	__u32 version;
+} __packed;
+
+union dm_caps {
+	struct {
+		__u64 balloon:1;
+		__u64 hot_add:1;
+		/*
+		 * To support guests that may have alignment
+		 * limitations on hot-add, the guest can specify
+		 * its alignment requirements; a value of n
+		 * represents an alignment of 2^n in mega bytes.
+		 */
+		__u64 hot_add_alignment:4;
+		__u64 reservedz:58;
+	} cap_bits;
+	__u64 caps;
+} __packed;
+
+union dm_mem_page_range {
+	struct  {
+		/*
+		 * The PFN number of the first page in the range.
+		 * 40 bits is the architectural limit of a PFN
+		 * number for AMD64.
+		 */
+		__u64 start_page:40;
+		/*
+		 * The number of pages in the range.
+		 */
+		__u64 page_cnt:24;
+	} finfo;
+	__u64  page_range;
+} __packed;
+
+/*
+ * The header for all dynamic memory messages:
+ *
+ * type: Type of the message.
+ * size: Size of the message in bytes; including the header.
+ * trans_id: The guest is responsible for manufacturing this ID.
+ */
+
+struct dm_header {
+	__u16 type;
+	__u16 size;
+	__u32 trans_id;
+} __packed;
+
+/*
+ * A generic message format for dynamic memory.
+ * Specific message formats are defined later in the file.
+ */
+
+struct dm_message {
+	struct dm_header hdr;
+	__u8 data[]; /* enclosed message */
+} __packed;
+
+/*
+ * Specific message types supporting the dynamic memory protocol.
+ */
+
+/*
+ * Version negotiation message. Sent from the guest to the host.
+ * The guest is free to try different versions until the host
+ * accepts the version.
+ *
+ * dm_version: The protocol version requested.
+ * is_last_attempt: If TRUE, this is the last version guest will request.
+ * reservedz: Reserved field, set to zero.
+ */
+
+struct dm_version_request {
+	struct dm_header hdr;
+	union dm_version version;
+	__u32 is_last_attempt:1;
+	__u32 reservedz:31;
+} __packed;
+
+/*
+ * Version response message; Host to Guest and indicates
+ * if the host has accepted the version sent by the guest.
+ *
+ * is_accepted: If TRUE, host has accepted the version and the guest
+ * should proceed to the next stage of the protocol. FALSE indicates that
+ * guest should re-try with a different version.
+ *
+ * reservedz: Reserved field, set to zero.
+ */
+
+struct dm_version_response {
+	struct dm_header hdr;
+	__u64 is_accepted:1;
+	__u64 reservedz:63;
+} __packed;
+
+/*
+ * Message reporting capabilities. This is sent from the guest to the
+ * host.
+ */
+
+struct dm_capabilities {
+	struct dm_header hdr;
+	union dm_caps caps;
+	__u64 min_page_cnt;
+	__u64 max_page_number;
+} __packed;
+
+/*
+ * Response to the capabilities message. This is sent from the host to the
+ * guest. This message notifies if the host has accepted the guest's
+ * capabilities. If the host has not accepted, the guest must shutdown
+ * the service.
+ *
+ * is_accepted: Indicates if the host has accepted guest's capabilities.
+ * reservedz: Must be 0.
+ */
+
+struct dm_capabilities_resp_msg {
+	struct dm_header hdr;
+	__u64 is_accepted:1;
+	__u64 reservedz:63;
+} __packed;
+
+/*
+ * This message is used to report memory pressure from the guest.
+ * This message is not part of any transaction and there is no
+ * response to this message.
+ *
+ * num_avail: Available memory in pages.
+ * num_committed: Committed memory in pages.
+ * page_file_size: The accumulated size of all page files
+ *		   in the system in pages.
+ * zero_free: The number of zero and free pages.
+ * page_file_writes: The writes to the page file in pages.
+ * io_diff: An indicator of file cache efficiency or page file activity,
+ *	    calculated as File Cache Page Fault Count - Page Read Count.
+ *	    This value is in pages.
+ *
+ * Some of these metrics are Windows specific and fortunately
+ * the algorithm on the host side that computes the guest memory
+ * pressure only uses num_committed value.
+ */
+
+struct dm_status {
+	struct dm_header hdr;
+	__u64 num_avail;
+	__u64 num_committed;
+	__u64 page_file_size;
+	__u64 zero_free;
+	__u32 page_file_writes;
+	__u32 io_diff;
+} __packed;
+
+/*
+ * Message to ask the guest to allocate memory - balloon up message.
+ * This message is sent from the host to the guest. The guest may not be
+ * able to allocate as much memory as requested.
+ *
+ * num_pages: number of pages to allocate.
+ */
+
+struct dm_balloon {
+	struct dm_header hdr;
+	__u32 num_pages;
+	__u32 reservedz;
+} __packed;
+
+/*
+ * Balloon response message; this message is sent from the guest
+ * to the host in response to the balloon message.
+ *
+ * reservedz: Reserved; must be set to zero.
+ * more_pages: If FALSE, this is the last message of the transaction.
+ * if TRUE there will be at least one more message from the guest.
+ *
+ * range_count: The number of ranges in the range array.
+ *
+ * range_array: An array of page ranges returned to the host.
+ *
+ */
+
+struct dm_balloon_response {
+	struct dm_header hdr;
+	__u32 reservedz;
+	__u32 more_pages:1;
+	__u32 range_count:31;
+	union dm_mem_page_range range_array[];
+} __packed;
+
+/*
+ * Un-balloon message; this message is sent from the host
+ * to the guest to give guest more memory.
+ *
+ * more_pages: If FALSE, this is the last message of the transaction.
+ * if TRUE there will be at least one more message from the guest.
+ *
+ * reservedz: Reserved; must be set to zero.
+ *
+ * range_count: The number of ranges in the range array.
+ *
+ * range_array: An array of page ranges returned to the host.
+ *
+ */
+
+struct dm_unballoon_request {
+	struct dm_header hdr;
+	__u32 more_pages:1;
+	__u32 reservedz:31;
+	__u32 range_count;
+	union dm_mem_page_range range_array[];
+} __packed;
+
+/*
+ * Un-balloon response message; this message is sent from the guest
+ * to the host in response to an unballoon request.
+ *
+ */
+
+struct dm_unballoon_response {
+	struct dm_header hdr;
+} __packed;
+
+/*
+ * Hot add request message. Message sent from the host to the guest.
+ *
+ * mem_range: Memory range to hot add.
+ *
+ */
+
+struct dm_hot_add {
+	struct dm_header hdr;
+	union dm_mem_page_range range;
+} __packed;
+
+/*
+ * Hot add response message.
+ * This message is sent by the guest to report the status of a hot add request.
+ * If page_count is less than the requested page count, then the host should
+ * assume all further hot add requests will fail, since this indicates that
+ * the guest has hit an upper physical memory barrier.
+ *
+ * Hot adds may also fail due to low resources; in this case, the guest must
+ * not complete this message until the hot add can succeed, and the host must
+ * not send a new hot add request until the response is sent.
+ * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
+ * times it fails the request.
+ *
+ *
+ * page_count: number of pages that were successfully hot added.
+ *
+ * result: result of the operation 1: success, 0: failure.
+ *
+ */
+
+struct dm_hot_add_response {
+	struct dm_header hdr;
+	__u32 page_count;
+	__u32 result;
+} __packed;
+
+/*
+ * Types of information sent from host to the guest.
+ */
+
+enum dm_info_type {
+	INFO_TYPE_MAX_PAGE_CNT = 0,
+	MAX_INFO_TYPE
+};
+
+/*
+ * Header for the information message.
+ */
+
+struct dm_info_header {
+	enum dm_info_type type;
+	__u32 data_size;
+} __packed;
+
+/*
+ * This message is sent from the host to the guest to pass
+ * some relevant information (win8 addition).
+ *
+ * reserved: no used.
+ * info_size: size of the information blob.
+ * info: information blob.
+ */
+
+struct dm_info_msg {
+	struct dm_header hdr;
+	__u32 reserved;
+	__u32 info_size;
+	__u8  info[];
+};
+
+/*
+ * End protocol definitions.
+ */
+
+/*
+ * State to manage hot adding memory into the guest.
+ * The range start_pfn : end_pfn specifies the range
+ * that the host has asked us to hot add. The range
+ * start_pfn : ha_end_pfn specifies the range that we have
+ * currently hot added. We hot add in chunks equal to the
+ * memory block size; it is possible that we may not be able
+ * to bring online all the pages in the region. The range
+ * covered_start_pfn:covered_end_pfn defines the pages that can
+ * be brought online.
+ */
+
+struct hv_hotadd_state {
+	struct list_head list;
+	unsigned long start_pfn;
+	unsigned long covered_start_pfn;
+	unsigned long covered_end_pfn;
+	unsigned long ha_end_pfn;
+	unsigned long end_pfn;
+	/*
+	 * A list of gaps.
+	 */
+	struct list_head gap_list;
+};
+
+struct hv_hotadd_gap {
+	struct list_head list;
+	unsigned long start_pfn;
+	unsigned long end_pfn;
+};
+
+struct balloon_state {
+	__u32 num_pages;
+	struct work_struct wrk;
+};
+
+struct hot_add_wrk {
+	union dm_mem_page_range ha_page_range;
+	union dm_mem_page_range ha_region_range;
+	struct work_struct wrk;
+};
+
+static bool allow_hibernation;
+static bool hot_add = true;
+static bool do_hot_add;
+/*
+ * Delay reporting memory pressure by
+ * the specified number of seconds.
+ */
+static uint pressure_report_delay = 45;
+extern unsigned int page_reporting_order;
+#define HV_MAX_FAILURES	2
+
+/*
+ * The last time we posted a pressure report to host.
+ */
+static unsigned long last_post_time;
+
+static int hv_hypercall_multi_failure;
+
+module_param(hot_add, bool, 0644);
+MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");
+
+module_param(pressure_report_delay, uint, 0644);
+MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
+static atomic_t trans_id = ATOMIC_INIT(0);
+
+static int dm_ring_size = VMBUS_RING_SIZE(16 * 1024);
+
+/*
+ * Driver specific state.
+ */
+
+enum hv_dm_state {
+	DM_INITIALIZING = 0,
+	DM_INITIALIZED,
+	DM_BALLOON_UP,
+	DM_BALLOON_DOWN,
+	DM_HOT_ADD,
+	DM_INIT_ERROR
+};
+
+static __u8 recv_buffer[HV_HYP_PAGE_SIZE];
+static __u8 balloon_up_send_buffer[HV_HYP_PAGE_SIZE];
+
+static unsigned long ha_pages_in_chunk;
+#define HA_BYTES_IN_CHUNK (ha_pages_in_chunk << PAGE_SHIFT)
+
+#define PAGES_IN_2M (2 * 1024 * 1024 / PAGE_SIZE)
+
+struct hv_dynmem_device {
+	struct hv_device *dev;
+	enum hv_dm_state state;
+	struct completion host_event;
+	struct completion config_event;
+
+	/*
+	 * Number of pages we have currently ballooned out.
+	 */
+	unsigned int num_pages_ballooned;
+	unsigned int num_pages_onlined;
+	unsigned int num_pages_added;
+
+	/*
+	 * State to manage the ballooning (up) operation.
+	 */
+	struct balloon_state balloon_wrk;
+
+	/*
+	 * State to execute the "hot-add" operation.
+	 */
+	struct hot_add_wrk ha_wrk;
+
+	/*
+	 * This state tracks if the host has specified a hot-add
+	 * region.
+	 */
+	bool host_specified_ha_region;
+
+	/*
+	 * State to synchronize hot-add.
+	 */
+	struct completion  ol_waitevent;
+	/*
+	 * This thread handles hot-add
+	 * requests from the host as well as notifying
+	 * the host with regards to memory pressure in
+	 * the guest.
+	 */
+	struct task_struct *thread;
+
+	/*
+	 * Protects ha_region_list, num_pages_onlined counter and individual
+	 * regions from ha_region_list.
+	 */
+	spinlock_t ha_lock;
+
+	/*
+	 * A list of hot-add regions.
+	 */
+	struct list_head ha_region_list;
+
+	/*
+	 * We start with the highest version we can support
+	 * and downgrade based on the host; we save here the
+	 * next version to try.
+	 */
+	__u32 next_version;
+
+	/*
+	 * The negotiated version agreed by host.
+	 */
+	__u32 version;
+
+	struct page_reporting_dev_info pr_dev_info;
+
+	/*
+	 * Maximum number of pages that can be hot_add-ed
+	 */
+	__u64 max_dynamic_page_count;
+};
+
+static struct hv_dynmem_device dm_device;
+
+static void post_status(struct hv_dynmem_device *dm);
+
+static void enable_page_reporting(void);
+
+static void disable_page_reporting(void);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static inline bool has_pfn_is_backed(struct hv_hotadd_state *has,
+				     unsigned long pfn)
+{
+	struct hv_hotadd_gap *gap;
+
+	/* The page is not backed. */
+	if (pfn < has->covered_start_pfn || pfn >= has->covered_end_pfn)
+		return false;
+
+	/* Check for gaps. */
+	list_for_each_entry(gap, &has->gap_list, list) {
+		if (pfn >= gap->start_pfn && pfn < gap->end_pfn)
+			return false;
+	}
+
+	return true;
+}
+
+static unsigned long hv_page_offline_check(unsigned long start_pfn,
+					   unsigned long nr_pages)
+{
+	unsigned long pfn = start_pfn, count = 0;
+	struct hv_hotadd_state *has;
+	bool found;
+
+	while (pfn < start_pfn + nr_pages) {
+		/*
+		 * Search for HAS which covers the pfn and when we find one
+		 * count how many consequitive PFNs are covered.
+		 */
+		found = false;
+		list_for_each_entry(has, &dm_device.ha_region_list, list) {
+			while ((pfn >= has->start_pfn) &&
+			       (pfn < has->end_pfn) &&
+			       (pfn < start_pfn + nr_pages)) {
+				found = true;
+				if (has_pfn_is_backed(has, pfn))
+					count++;
+				pfn++;
+			}
+		}
+
+		/*
+		 * This PFN is not in any HAS (e.g. we're offlining a region
+		 * which was present at boot), no need to account for it. Go
+		 * to the next one.
+		 */
+		if (!found)
+			pfn++;
+	}
+
+	return count;
+}
+
+static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
+			      void *v)
+{
+	struct memory_notify *mem = (struct memory_notify *)v;
+	unsigned long pfn_count;
+
+	switch (val) {
+	case MEM_ONLINE:
+	case MEM_CANCEL_ONLINE:
+		complete(&dm_device.ol_waitevent);
+		break;
+
+	case MEM_OFFLINE:
+		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
+			pfn_count = hv_page_offline_check(mem->start_pfn,
+							  mem->nr_pages);
+			if (pfn_count <= dm_device.num_pages_onlined) {
+				dm_device.num_pages_onlined -= pfn_count;
+			} else {
+				/*
+				 * We're offlining more pages than we
+				 * managed to online. This is
+				 * unexpected. In any case don't let
+				 * num_pages_onlined wrap around zero.
+				 */
+				WARN_ON_ONCE(1);
+				dm_device.num_pages_onlined = 0;
+			}
+		}
+		break;
+	case MEM_GOING_ONLINE:
+	case MEM_GOING_OFFLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block hv_memory_nb = {
+	.notifier_call = hv_memory_notifier,
+	.priority = 0
+};
+
+/* Check if the particular page is backed and can be onlined and online it. */
+static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
+{
+	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
+		if (!PageOffline(pg))
+			__SetPageOffline(pg);
+		return;
+	} else if (!PageOffline(pg))
+		return;
+
+	/* This frame is currently backed; online the page. */
+	generic_online_page(pg, 0);
+
+	lockdep_assert_held(&dm_device.ha_lock);
+	dm_device.num_pages_onlined++;
+}
+
+static void hv_bring_pgs_online(struct hv_hotadd_state *has,
+				unsigned long start_pfn, unsigned long size)
+{
+	int i;
+
+	pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
+	for (i = 0; i < size; i++)
+		hv_page_online_one(has, pfn_to_page(start_pfn + i));
+}
+
+static void hv_mem_hot_add(unsigned long start, unsigned long size,
+				unsigned long pfn_count,
+				struct hv_hotadd_state *has)
+{
+	int ret = 0;
+	int i, nid;
+	unsigned long start_pfn;
+	unsigned long processed_pfn;
+	unsigned long total_pfn = pfn_count;
+
+	for (i = 0; i < (size/ha_pages_in_chunk); i++) {
+		start_pfn = start + (i * ha_pages_in_chunk);
+
+		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
+			has->ha_end_pfn += ha_pages_in_chunk;
+			processed_pfn = umin(total_pfn, ha_pages_in_chunk);
+			total_pfn -= processed_pfn;
+			has->covered_end_pfn += processed_pfn;
+		}
+
+		reinit_completion(&dm_device.ol_waitevent);
+
+		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
+		ret = add_memory(nid, PFN_PHYS((start_pfn)),
+				 HA_BYTES_IN_CHUNK, MHP_MERGE_RESOURCE);
+
+		if (ret) {
+			pr_err("hot_add memory failed error is %d\n", ret);
+			if (ret == -EEXIST) {
+				/*
+				 * This error indicates that the error
+				 * is not a transient failure. This is the
+				 * case where the guest's physical address map
+				 * precludes hot adding memory. Stop all further
+				 * memory hot-add.
+				 */
+				do_hot_add = false;
+			}
+			scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
+				has->ha_end_pfn -= ha_pages_in_chunk;
+				has->covered_end_pfn -=  processed_pfn;
+			}
+			break;
+		}
+
+		/*
+		 * Wait for memory to get onlined. If the kernel onlined the
+		 * memory when adding it, this will return directly. Otherwise,
+		 * it will wait for user space to online the memory. This helps
+		 * to avoid adding memory faster than it is getting onlined. As
+		 * adding succeeded, it is ok to proceed even if the memory was
+		 * not onlined in time.
+		 */
+		wait_for_completion_timeout(&dm_device.ol_waitevent, secs_to_jiffies(5));
+		post_status(&dm_device);
+	}
+}
+
+static void hv_online_page(struct page *pg, unsigned int order)
+{
+	struct hv_hotadd_state *has;
+	unsigned long pfn = page_to_pfn(pg);
+
+	scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
+		list_for_each_entry(has, &dm_device.ha_region_list, list) {
+			/* The page belongs to a different HAS. */
+			if (pfn < has->start_pfn ||
+				(pfn + (1UL << order) > has->end_pfn))
+				continue;
+
+			hv_bring_pgs_online(has, pfn, 1UL << order);
+			return;
+		}
+	}
+	generic_online_page(pg, order);
+}
+
+static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
+{
+	struct hv_hotadd_state *has;
+	struct hv_hotadd_gap *gap;
+	unsigned long residual;
+	int ret = 0;
+
+	guard(spinlock_irqsave)(&dm_device.ha_lock);
+	list_for_each_entry(has, &dm_device.ha_region_list, list) {
+		/*
+		 * If the pfn range we are dealing with is not in the current
+		 * "hot add block", move on.
+		 */
+		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
+			continue;
+
+		/*
+		 * If the current start pfn is not where the covered_end
+		 * is, create a gap and update covered_end_pfn.
+		 */
+		if (has->covered_end_pfn != start_pfn) {
+			gap = kzalloc_obj(struct hv_hotadd_gap, GFP_ATOMIC);
+			if (!gap) {
+				ret = -ENOMEM;
+				break;
+			}
+
+			INIT_LIST_HEAD(&gap->list);
+			gap->start_pfn = has->covered_end_pfn;
+			gap->end_pfn = start_pfn;
+			list_add_tail(&gap->list, &has->gap_list);
+
+			has->covered_end_pfn = start_pfn;
+		}
+
+		/*
+		 * If the current hot add-request extends beyond
+		 * our current limit; extend it.
+		 */
+		if ((start_pfn + pfn_cnt) > has->end_pfn) {
+			/* Extend the region by multiples of ha_pages_in_chunk */
+			residual = (start_pfn + pfn_cnt - has->end_pfn);
+			has->end_pfn += ALIGN(residual, ha_pages_in_chunk);
+		}
+
+		ret = 1;
+		break;
+	}
+
+	return ret;
+}
+
+static unsigned long handle_pg_range(unsigned long pg_start,
+				     unsigned long pg_count)
+{
+	unsigned long start_pfn = pg_start;
+	unsigned long pfn_cnt = pg_count;
+	unsigned long size;
+	struct hv_hotadd_state *has;
+	unsigned long pgs_ol = 0;
+	unsigned long old_covered_state;
+	unsigned long res = 0, flags;
+
+	pr_debug("Hot adding %lu pages starting at pfn 0x%lx.\n", pg_count,
+		 pg_start);
+
+	spin_lock_irqsave(&dm_device.ha_lock, flags);
+	list_for_each_entry(has, &dm_device.ha_region_list, list) {
+		/*
+		 * If the pfn range we are dealing with is not in the current
+		 * "hot add block", move on.
+		 */
+		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
+			continue;
+
+		old_covered_state = has->covered_end_pfn;
+
+		if (start_pfn < has->ha_end_pfn) {
+			/*
+			 * This is the case where we are backing pages
+			 * in an already hot added region. Bring
+			 * these pages online first.
+			 */
+			pgs_ol = has->ha_end_pfn - start_pfn;
+			if (pgs_ol > pfn_cnt)
+				pgs_ol = pfn_cnt;
+
+			has->covered_end_pfn +=  pgs_ol;
+			pfn_cnt -= pgs_ol;
+			/*
+			 * Check if the corresponding memory block is already
+			 * online. It is possible to observe struct pages still
+			 * being uninitialized here so check section instead.
+			 * In case the section is online we need to bring the
+			 * rest of pfns (which were not backed previously)
+			 * online too.
+			 */
+			if (start_pfn > has->start_pfn &&
+			    online_section_nr(pfn_to_section_nr(start_pfn)))
+				hv_bring_pgs_online(has, start_pfn, pgs_ol);
+		}
+
+		if (has->ha_end_pfn < has->end_pfn && pfn_cnt > 0) {
+			/*
+			 * We have some residual hot add range
+			 * that needs to be hot added; hot add
+			 * it now. Hot add a multiple of
+			 * ha_pages_in_chunk that fully covers the pages
+			 * we have.
+			 */
+			size = (has->end_pfn - has->ha_end_pfn);
+			if (pfn_cnt <= size) {
+				size = ALIGN(pfn_cnt, ha_pages_in_chunk);
+			} else {
+				pfn_cnt = size;
+			}
+			spin_unlock_irqrestore(&dm_device.ha_lock, flags);
+			hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has);
+			spin_lock_irqsave(&dm_device.ha_lock, flags);
+		}
+		/*
+		 * If we managed to online any pages that were given to us,
+		 * we declare success.
+		 */
+		res = has->covered_end_pfn - old_covered_state;
+		break;
+	}
+	spin_unlock_irqrestore(&dm_device.ha_lock, flags);
+
+	return res;
+}
+
+static unsigned long process_hot_add(unsigned long pg_start,
+					unsigned long pfn_cnt,
+					unsigned long rg_start,
+					unsigned long rg_size)
+{
+	struct hv_hotadd_state *ha_region = NULL;
+	int covered;
+
+	if (pfn_cnt == 0)
+		return 0;
+
+	if (!dm_device.host_specified_ha_region) {
+		covered = pfn_covered(pg_start, pfn_cnt);
+		if (covered < 0)
+			return 0;
+
+		if (covered)
+			goto do_pg_range;
+	}
+
+	/*
+	 * If the host has specified a hot-add range; deal with it first.
+	 */
+
+	if (rg_size != 0) {
+		ha_region = kzalloc_obj(struct hv_hotadd_state);
+		if (!ha_region)
+			return 0;
+
+		INIT_LIST_HEAD(&ha_region->list);
+		INIT_LIST_HEAD(&ha_region->gap_list);
+
+		ha_region->start_pfn = rg_start;
+		ha_region->ha_end_pfn = rg_start;
+		ha_region->covered_start_pfn = pg_start;
+		ha_region->covered_end_pfn = pg_start;
+		ha_region->end_pfn = rg_start + rg_size;
+
+		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
+			list_add_tail(&ha_region->list, &dm_device.ha_region_list);
+		}
+	}
+
+do_pg_range:
+	/*
+	 * Process the page range specified; bringing them
+	 * online if possible.
+	 */
+	return handle_pg_range(pg_start, pfn_cnt);
+}
+
+#endif
+
+static void hot_add_req(struct work_struct *dummy)
+{
+	struct dm_hot_add_response resp;
+#ifdef CONFIG_MEMORY_HOTPLUG
+	unsigned long pg_start, pfn_cnt;
+	unsigned long rg_start, rg_sz;
+#endif
+	struct hv_dynmem_device *dm = &dm_device;
+
+	memset(&resp, 0, sizeof(struct dm_hot_add_response));
+	resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
+	resp.hdr.size = sizeof(struct dm_hot_add_response);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+	pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
+	pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
+
+	rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
+	rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;
+
+	if (rg_start == 0 && !dm->host_specified_ha_region) {
+		/*
+		 * The host has not specified the hot-add region.
+		 * Based on the hot-add page range being specified,
+		 * compute a hot-add region that can cover the pages
+		 * that need to be hot-added while ensuring the alignment
+		 * and size requirements of Linux as it relates to hot-add.
+		 */
+		rg_start = ALIGN_DOWN(pg_start, ha_pages_in_chunk);
+		rg_sz = ALIGN(pfn_cnt, ha_pages_in_chunk);
+	}
+
+	if (do_hot_add)
+		resp.page_count = process_hot_add(pg_start, pfn_cnt,
+						  rg_start, rg_sz);
+
+	dm->num_pages_added += resp.page_count;
+#endif
+	/*
+	 * The result field of the response structure has the
+	 * following semantics:
+	 *
+	 * 1. If all or some pages hot-added: Guest should return success.
+	 *
+	 * 2. If no pages could be hot-added:
+	 *
+	 * If the guest returns success, then the host
+	 * will not attempt any further hot-add operations. This
+	 * signifies a permanent failure.
+	 *
+	 * If the guest returns failure, then this failure will be
+	 * treated as a transient failure and the host may retry the
+	 * hot-add operation after some delay.
+	 */
+	if (resp.page_count > 0)
+		resp.result = 1;
+	else if (!do_hot_add)
+		resp.result = 1;
+	else
+		resp.result = 0;
+
+	if (!do_hot_add || resp.page_count == 0) {
+		if (!allow_hibernation)
+			pr_err("Memory hot add failed\n");
+		else
+			pr_info("Ignore hot-add request!\n");
+	}
+
+	dm->state = DM_INITIALIZED;
+	resp.hdr.trans_id = atomic_inc_return(&trans_id);
+	vmbus_sendpacket(dm->dev->channel, &resp,
+			sizeof(struct dm_hot_add_response),
+			(unsigned long)NULL,
+			VM_PKT_DATA_INBAND, 0);
+}
+
+static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
+{
+	struct dm_info_header *info_hdr;
+
+	info_hdr = (struct dm_info_header *)msg->info;
+
+	switch (info_hdr->type) {
+	case INFO_TYPE_MAX_PAGE_CNT:
+		if (info_hdr->data_size == sizeof(__u64)) {
+			__u64 *max_page_count = (__u64 *)&info_hdr[1];
+
+			pr_info("Max. dynamic memory size: %llu MB\n",
+				(*max_page_count) >> (20 - HV_HYP_PAGE_SHIFT));
+			dm->max_dynamic_page_count = *max_page_count;
+		}
+
+		break;
+	default:
+		pr_warn("Received Unknown type: %d\n", info_hdr->type);
+	}
+}
+
+static unsigned long compute_balloon_floor(void)
+{
+	unsigned long min_pages;
+	unsigned long nr_pages = totalram_pages();
+#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
+	/* Simple continuous piecewiese linear function:
+	 *  max MiB -> min MiB  gradient
+	 *       0         0
+	 *      16        16
+	 *      32        24
+	 *     128        72    (1/2)
+	 *     512       168    (1/4)
+	 *    2048       360    (1/8)
+	 *    8192       744    (1/16)
+	 *   32768      1512	(1/32)
+	 */
+	if (nr_pages < MB2PAGES(128))
+		min_pages = MB2PAGES(8) + (nr_pages >> 1);
+	else if (nr_pages < MB2PAGES(512))
+		min_pages = MB2PAGES(40) + (nr_pages >> 2);
+	else if (nr_pages < MB2PAGES(2048))
+		min_pages = MB2PAGES(104) + (nr_pages >> 3);
+	else if (nr_pages < MB2PAGES(8192))
+		min_pages = MB2PAGES(232) + (nr_pages >> 4);
+	else
+		min_pages = MB2PAGES(488) + (nr_pages >> 5);
+#undef MB2PAGES
+	return min_pages;
+}
+
+/*
+ * Compute total committed memory pages
+ */
+
+static unsigned long get_pages_committed(struct hv_dynmem_device *dm)
+{
+	return vm_memory_committed() +
+		dm->num_pages_ballooned +
+		(dm->num_pages_added > dm->num_pages_onlined ?
+		 dm->num_pages_added - dm->num_pages_onlined : 0) +
+		compute_balloon_floor();
+}
+
+/*
+ * Post our status as it relates memory pressure to the
+ * host. Host expects the guests to post this status
+ * periodically at 1 second intervals.
+ *
+ * The metrics specified in this protocol are very Windows
+ * specific and so we cook up numbers here to convey our memory
+ * pressure.
+ */
+
+static void post_status(struct hv_dynmem_device *dm)
+{
+	struct dm_status status;
+	unsigned long now = jiffies;
+	unsigned long last_post = last_post_time;
+	unsigned long num_pages_avail, num_pages_committed;
+
+	if (pressure_report_delay > 0) {
+		--pressure_report_delay;
+		return;
+	}
+
+	if (!time_after(now, (last_post_time + HZ)))
+		return;
+
+	memset(&status, 0, sizeof(struct dm_status));
+	status.hdr.type = DM_STATUS_REPORT;
+	status.hdr.size = sizeof(struct dm_status);
+	status.hdr.trans_id = atomic_inc_return(&trans_id);
+
+	/*
+	 * The host expects the guest to report free and committed memory.
+	 * Furthermore, the host expects the pressure information to include
+	 * the ballooned out pages. For a given amount of memory that we are
+	 * managing we need to compute a floor below which we should not
+	 * balloon. Compute this and add it to the pressure report.
+	 * We also need to report all offline pages (num_pages_added -
+	 * num_pages_onlined) as committed to the host, otherwise it can try
+	 * asking us to balloon them out.
+	 */
+	num_pages_avail = si_mem_available();
+	num_pages_committed = get_pages_committed(dm);
+
+	trace_balloon_status(num_pages_avail, num_pages_committed,
+			     vm_memory_committed(), dm->num_pages_ballooned,
+			     dm->num_pages_added, dm->num_pages_onlined);
+
+	/* Convert numbers of pages into numbers of HV_HYP_PAGEs. */
+	status.num_avail = num_pages_avail * NR_HV_HYP_PAGES_IN_PAGE;
+	status.num_committed = num_pages_committed * NR_HV_HYP_PAGES_IN_PAGE;
+
+	/*
+	 * If our transaction ID is no longer current, just don't
+	 * send the status. This can happen if we were interrupted
+	 * after we picked our transaction ID.
+	 */
+	if (status.hdr.trans_id != atomic_read(&trans_id))
+		return;
+
+	/*
+	 * If the last post time that we sampled has changed,
+	 * we have raced, don't post the status.
+	 */
+	if (last_post != last_post_time)
+		return;
+
+	last_post_time = jiffies;
+	vmbus_sendpacket(dm->dev->channel, &status,
+				sizeof(struct dm_status),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+}
+
+static void free_balloon_pages(struct hv_dynmem_device *dm,
+			       union dm_mem_page_range *range_array)
+{
+	int num_pages = range_array->finfo.page_cnt;
+	__u64 start_frame = range_array->finfo.start_page;
+	struct page *pg;
+	int i;
+
+	for (i = 0; i < num_pages; i++) {
+		pg = pfn_to_page(i + start_frame);
+		__ClearPageOffline(pg);
+		__free_page(pg);
+		dm->num_pages_ballooned--;
+		mod_node_page_state(page_pgdat(pg), NR_BALLOON_PAGES, -1);
+		adjust_managed_page_count(pg, 1);
+	}
+}
+
+static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
+					unsigned int num_pages,
+					struct dm_balloon_response *bl_resp,
+					int alloc_unit)
+{
+	unsigned int i, j;
+	struct page *pg;
+
+	for (i = 0; i < num_pages / alloc_unit; i++) {
+		if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
+			HV_HYP_PAGE_SIZE)
+			return i * alloc_unit;
+
+		/*
+		 * We execute this code in a thread context. Furthermore,
+		 * we don't want the kernel to try too hard.
+		 */
+		pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
+				__GFP_NOMEMALLOC | __GFP_NOWARN,
+				get_order(alloc_unit << PAGE_SHIFT));
+
+		if (!pg)
+			return i * alloc_unit;
+
+		dm->num_pages_ballooned += alloc_unit;
+		mod_node_page_state(page_pgdat(pg), NR_BALLOON_PAGES, alloc_unit);
+
+		/*
+		 * If we allocatted 2M pages; split them so we
+		 * can free them in any order we get.
+		 */
+
+		if (alloc_unit != 1)
+			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
+
+		/* mark all pages offline */
+		for (j = 0; j < alloc_unit; j++) {
+			__SetPageOffline(pg + j);
+			adjust_managed_page_count(pg + j, -1);
+		}
+
+		bl_resp->range_count++;
+		bl_resp->range_array[i].finfo.start_page =
+			page_to_pfn(pg);
+		bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
+		bl_resp->hdr.size += sizeof(union dm_mem_page_range);
+	}
+
+	return i * alloc_unit;
+}
+
+static void balloon_up(struct work_struct *dummy)
+{
+	unsigned int num_pages = dm_device.balloon_wrk.num_pages;
+	unsigned int num_ballooned = 0;
+	struct dm_balloon_response *bl_resp;
+	int alloc_unit;
+	int ret;
+	bool done = false;
+	int i;
+	long avail_pages;
+	unsigned long floor;
+
+	/*
+	 * We will attempt 2M allocations. However, if we fail to
+	 * allocate 2M chunks, we will go back to PAGE_SIZE allocations.
+	 */
+	alloc_unit = PAGES_IN_2M;
+
+	avail_pages = si_mem_available();
+	floor = compute_balloon_floor();
+
+	/* Refuse to balloon below the floor. */
+	if (avail_pages < num_pages || avail_pages - num_pages < floor) {
+		pr_info("Balloon request will be partially fulfilled. %s\n",
+			avail_pages < num_pages ? "Not enough memory." :
+			"Balloon floor reached.");
+
+		num_pages = avail_pages > floor ? (avail_pages - floor) : 0;
+	}
+
+	while (!done) {
+		memset(balloon_up_send_buffer, 0, HV_HYP_PAGE_SIZE);
+		bl_resp = (struct dm_balloon_response *)balloon_up_send_buffer;
+		bl_resp->hdr.type = DM_BALLOON_RESPONSE;
+		bl_resp->hdr.size = sizeof(struct dm_balloon_response);
+		bl_resp->more_pages = 1;
+
+		num_pages -= num_ballooned;
+		num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
+						    bl_resp, alloc_unit);
+
+		if (alloc_unit != 1 && num_ballooned == 0) {
+			alloc_unit = 1;
+			continue;
+		}
+
+		if (num_ballooned == 0 || num_ballooned == num_pages) {
+			pr_debug("Ballooned %u out of %u requested pages.\n",
+				 num_pages, dm_device.balloon_wrk.num_pages);
+
+			bl_resp->more_pages = 0;
+			done = true;
+			dm_device.state = DM_INITIALIZED;
+		}
+
+		/*
+		 * We are pushing a lot of data through the channel;
+		 * deal with transient failures caused because of the
+		 * lack of space in the ring buffer.
+		 */
+
+		do {
+			bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
+			ret = vmbus_sendpacket(dm_device.dev->channel,
+						bl_resp,
+						bl_resp->hdr.size,
+						(unsigned long)NULL,
+						VM_PKT_DATA_INBAND, 0);
+
+			if (ret == -EAGAIN)
+				msleep(20);
+			post_status(&dm_device);
+		} while (ret == -EAGAIN);
+
+		if (ret) {
+			/*
+			 * Free up the memory we allocatted.
+			 */
+			pr_err("Balloon response failed\n");
+
+			for (i = 0; i < bl_resp->range_count; i++)
+				free_balloon_pages(&dm_device,
+						   &bl_resp->range_array[i]);
+
+			done = true;
+		}
+	}
+}
+
+static void balloon_down(struct hv_dynmem_device *dm,
+			 struct dm_unballoon_request *req)
+{
+	union dm_mem_page_range *range_array = req->range_array;
+	int range_count = req->range_count;
+	struct dm_unballoon_response resp;
+	int i;
+	unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
+
+	for (i = 0; i < range_count; i++) {
+		free_balloon_pages(dm, &range_array[i]);
+		complete(&dm_device.config_event);
+	}
+
+	pr_debug("Freed %u ballooned pages.\n",
+		 prev_pages_ballooned - dm->num_pages_ballooned);
+
+	if (req->more_pages == 1)
+		return;
+
+	memset(&resp, 0, sizeof(struct dm_unballoon_response));
+	resp.hdr.type = DM_UNBALLOON_RESPONSE;
+	resp.hdr.trans_id = atomic_inc_return(&trans_id);
+	resp.hdr.size = sizeof(struct dm_unballoon_response);
+
+	vmbus_sendpacket(dm_device.dev->channel, &resp,
+				sizeof(struct dm_unballoon_response),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+
+	dm->state = DM_INITIALIZED;
+}
+
+static void balloon_onchannelcallback(void *context);
+
+static int dm_thread_func(void *dm_dev)
+{
+	struct hv_dynmem_device *dm = dm_dev;
+
+	while (!kthread_should_stop()) {
+		wait_for_completion_interruptible_timeout(&dm_device.config_event,
+								secs_to_jiffies(1));
+		/*
+		 * The host expects us to post information on the memory
+		 * pressure every second.
+		 */
+		reinit_completion(&dm_device.config_event);
+		post_status(dm);
+		/*
+		 * disable free page reporting if multiple hypercall
+		 * failure flag set. It is not done in the page_reporting
+		 * callback context as that causes a deadlock between
+		 * page_reporting_process() and page_reporting_unregister()
+		 */
+		if (hv_hypercall_multi_failure >= HV_MAX_FAILURES) {
+			pr_err("Multiple failures in cold memory discard hypercall, disabling page reporting\n");
+			disable_page_reporting();
+			/* Reset the flag after disabling reporting */
+			hv_hypercall_multi_failure = 0;
+		}
+	}
+
+	return 0;
+}
+
+static void version_resp(struct hv_dynmem_device *dm,
+			 struct dm_version_response *vresp)
+{
+	struct dm_version_request version_req;
+	int ret;
+
+	if (vresp->is_accepted) {
+		/*
+		 * We are done; wakeup the
+		 * context waiting for version
+		 * negotiation.
+		 */
+		complete(&dm->host_event);
+		return;
+	}
+	/*
+	 * If there are more versions to try, continue
+	 * with negotiations; if not
+	 * shutdown the service since we are not able
+	 * to negotiate a suitable version number
+	 * with the host.
+	 */
+	if (dm->next_version == 0)
+		goto version_error;
+
+	memset(&version_req, 0, sizeof(struct dm_version_request));
+	version_req.hdr.type = DM_VERSION_REQUEST;
+	version_req.hdr.size = sizeof(struct dm_version_request);
+	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
+	version_req.version.version = dm->next_version;
+	dm->version = version_req.version.version;
+
+	/* Set the next version to try in case current version fails. */
+	dm->next_version = 0;
+	version_req.is_last_attempt = 1;
+
+	ret = vmbus_sendpacket(dm->dev->channel, &version_req,
+				sizeof(struct dm_version_request),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+
+	if (ret)
+		goto version_error;
+
+	return;
+
+version_error:
+	dm->state = DM_INIT_ERROR;
+	complete(&dm->host_event);
+}
+
+static void cap_resp(struct hv_dynmem_device *dm,
+		     struct dm_capabilities_resp_msg *cap_resp)
+{
+	if (!cap_resp->is_accepted) {
+		pr_err("Capabilities not accepted by host\n");
+		dm->state = DM_INIT_ERROR;
+	}
+	complete(&dm->host_event);
+}
+
+static void balloon_onchannelcallback(void *context)
+{
+	struct hv_device *dev = context;
+	u32 recvlen;
+	u64 requestid;
+	struct dm_message *dm_msg;
+	struct dm_header *dm_hdr;
+	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
+	struct dm_balloon *bal_msg;
+	struct dm_hot_add *ha_msg;
+	union dm_mem_page_range *ha_pg_range;
+	union dm_mem_page_range *ha_region;
+
+	memset(recv_buffer, 0, sizeof(recv_buffer));
+	vmbus_recvpacket(dev->channel, recv_buffer,
+			 HV_HYP_PAGE_SIZE, &recvlen, &requestid);
+
+	if (recvlen > 0) {
+		dm_msg = (struct dm_message *)recv_buffer;
+		dm_hdr = &dm_msg->hdr;
+
+		switch (dm_hdr->type) {
+		case DM_VERSION_RESPONSE:
+			version_resp(dm,
+				     (struct dm_version_response *)dm_msg);
+			break;
+
+		case DM_CAPABILITIES_RESPONSE:
+			cap_resp(dm,
+				 (struct dm_capabilities_resp_msg *)dm_msg);
+			break;
+
+		case DM_BALLOON_REQUEST:
+			if (allow_hibernation) {
+				pr_info("Ignore balloon-up request!\n");
+				break;
+			}
+
+			if (dm->state == DM_BALLOON_UP)
+				pr_warn("Currently ballooning\n");
+			bal_msg = (struct dm_balloon *)recv_buffer;
+			dm->state = DM_BALLOON_UP;
+			dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
+			schedule_work(&dm_device.balloon_wrk.wrk);
+			break;
+
+		case DM_UNBALLOON_REQUEST:
+			if (allow_hibernation) {
+				pr_info("Ignore balloon-down request!\n");
+				break;
+			}
+
+			dm->state = DM_BALLOON_DOWN;
+			balloon_down(dm,
+				     (struct dm_unballoon_request *)recv_buffer);
+			break;
+
+		case DM_MEM_HOT_ADD_REQUEST:
+			if (dm->state == DM_HOT_ADD)
+				pr_warn("Currently hot-adding\n");
+			dm->state = DM_HOT_ADD;
+			ha_msg = (struct dm_hot_add *)recv_buffer;
+			if (ha_msg->hdr.size == sizeof(struct dm_hot_add)) {
+				/*
+				 * This is a normal hot-add request specifying
+				 * hot-add memory.
+				 */
+				dm->host_specified_ha_region = false;
+				ha_pg_range = &ha_msg->range;
+				dm->ha_wrk.ha_page_range = *ha_pg_range;
+				dm->ha_wrk.ha_region_range.page_range = 0;
+			} else {
+				/*
+				 * Host is specifying that we first hot-add
+				 * a region and then partially populate this
+				 * region.
+				 */
+				dm->host_specified_ha_region = true;
+				ha_pg_range = &ha_msg->range;
+				ha_region = &ha_pg_range[1];
+				dm->ha_wrk.ha_page_range = *ha_pg_range;
+				dm->ha_wrk.ha_region_range = *ha_region;
+			}
+			schedule_work(&dm_device.ha_wrk.wrk);
+			break;
+
+		case DM_INFO_MESSAGE:
+			process_info(dm, (struct dm_info_msg *)dm_msg);
+			break;
+
+		default:
+			pr_warn_ratelimited("Unhandled message: type: %d\n", dm_hdr->type);
+		}
+	}
+}
+
+#define HV_LARGE_REPORTING_ORDER	9
+#define HV_LARGE_REPORTING_LEN (HV_HYP_PAGE_SIZE << \
+		HV_LARGE_REPORTING_ORDER)
+static int hv_free_page_report(struct page_reporting_dev_info *pr_dev_info,
+			       struct scatterlist *sgl, unsigned int nents)
+{
+	unsigned long flags;
+	struct hv_memory_hint *hint;
+	int i, order;
+	u64 status;
+	struct scatterlist *sg;
+
+	WARN_ON_ONCE(nents > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES);
+	WARN_ON_ONCE(sgl->length < (HV_HYP_PAGE_SIZE << page_reporting_order));
+	local_irq_save(flags);
+	hint = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	if (!hint) {
+		local_irq_restore(flags);
+		return -ENOSPC;
+	}
+
+	hint->heat_type = HV_EXTMEM_HEAT_HINT_COLD_DISCARD;
+	hint->reserved = 0;
+	for_each_sg(sgl, sg, nents, i) {
+		union hv_gpa_page_range *range;
+
+		range = &hint->ranges[i];
+		range->address_space = 0;
+		order = get_order(sg->length);
+		/*
+		 * Hyper-V expects the additional_pages field in the units
+		 * of one of these 3 sizes, 4Kbytes, 2Mbytes or 1Gbytes.
+		 * This is dictated by the values of the fields page.largesize
+		 * and page_size.
+		 * This code however, only uses 4Kbytes and 2Mbytes units
+		 * and not 1Gbytes unit.
+		 */
+
+		/* page reporting for pages 2MB or higher */
+		if (order >= HV_LARGE_REPORTING_ORDER) {
+			range->page.largepage = 1;
+			range->page_size = HV_GPA_PAGE_RANGE_PAGE_SIZE_2MB;
+			range->base_large_pfn = page_to_hvpfn(
+					sg_page(sg)) >> HV_LARGE_REPORTING_ORDER;
+			range->page.additional_pages =
+				(sg->length / HV_LARGE_REPORTING_LEN) - 1;
+		} else {
+			/* Page reporting for pages below 2MB */
+			range->page.basepfn = page_to_hvpfn(sg_page(sg));
+			range->page.largepage = false;
+			range->page.additional_pages =
+				(sg->length / HV_HYP_PAGE_SIZE) - 1;
+		}
+	}
+
+	status = hv_do_rep_hypercall(HV_EXT_CALL_MEMORY_HEAT_HINT, nents, 0,
+				     hint, NULL);
+	local_irq_restore(flags);
+	if (!hv_result_success(status)) {
+		pr_err("Cold memory discard hypercall failed with status %llx\n",
+		       status);
+		if (hv_hypercall_multi_failure > 0)
+			hv_hypercall_multi_failure++;
+
+		if (hv_result(status) == HV_STATUS_INVALID_PARAMETER) {
+			pr_err("Underlying Hyper-V does not support order less than 9. Hypercall failed\n");
+			pr_err("Defaulting to page_reporting_order %d\n",
+			       pageblock_order);
+			page_reporting_order = pageblock_order;
+			hv_hypercall_multi_failure++;
+			return -EINVAL;
+		}
+
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void enable_page_reporting(void)
+{
+	int ret;
+
+	if (!hv_query_ext_cap(HV_EXT_CAPABILITY_MEMORY_COLD_DISCARD_HINT)) {
+		pr_debug("Cold memory discard hint not supported by Hyper-V\n");
+		return;
+	}
+
+	BUILD_BUG_ON(PAGE_REPORTING_CAPACITY > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES);
+	dm_device.pr_dev_info.report = hv_free_page_report;
+	/*
+	 * We let the page_reporting_order parameter decide the order
+	 * in the page_reporting code
+	 */
+	dm_device.pr_dev_info.order = PAGE_REPORTING_ORDER_UNSPECIFIED;
+	ret = page_reporting_register(&dm_device.pr_dev_info);
+	if (ret < 0) {
+		dm_device.pr_dev_info.report = NULL;
+		pr_err("Failed to enable cold memory discard: %d\n", ret);
+	} else {
+		pr_info("Cold memory discard hint enabled with order %d\n",
+			page_reporting_order);
+	}
+}
+
+static void disable_page_reporting(void)
+{
+	if (dm_device.pr_dev_info.report) {
+		page_reporting_unregister(&dm_device.pr_dev_info);
+		dm_device.pr_dev_info.report = NULL;
+	}
+}
+
+static int ballooning_enabled(void)
+{
+	/*
+	 * Disable ballooning if the page size is not 4k (HV_HYP_PAGE_SIZE),
+	 * since currently it's unclear to us whether an unballoon request can
+	 * make sure all page ranges are guest page size aligned.
+	 */
+	if (PAGE_SIZE != HV_HYP_PAGE_SIZE) {
+		pr_info("Ballooning disabled because page size is not 4096 bytes\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static int hot_add_enabled(void)
+{
+	/*
+	 * Disable hot add on ARM64, because we currently rely on
+	 * memory_add_physaddr_to_nid() to get a node id of a hot add range,
+	 * however ARM64's memory_add_physaddr_to_nid() always return 0 and
+	 * DM_MEM_HOT_ADD_REQUEST doesn't have the NUMA node information for
+	 * add_memory().
+	 */
+	if (IS_ENABLED(CONFIG_ARM64)) {
+		pr_info("Memory hot add disabled on ARM64\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static int balloon_connect_vsp(struct hv_device *dev)
+{
+	struct dm_version_request version_req;
+	struct dm_capabilities cap_msg;
+	unsigned long t;
+	int ret;
+
+	/*
+	 * max_pkt_size should be large enough for one vmbus packet header plus
+	 * our receive buffer size. Hyper-V sends messages up to
+	 * HV_HYP_PAGE_SIZE bytes long on balloon channel.
+	 */
+	dev->channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2;
+
+	ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
+			 balloon_onchannelcallback, dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Initiate the hand shake with the host and negotiate
+	 * a version that the host can support. The mechanism is in place
+	 * to start with the highest version number and go down if the host
+	 * cannot support it. But currently we only try the WIN10 version
+	 * since support for older Hyper-V versions has been removed from
+	 * Linux.
+	 */
+	memset(&version_req, 0, sizeof(struct dm_version_request));
+	version_req.hdr.type = DM_VERSION_REQUEST;
+	version_req.hdr.size = sizeof(struct dm_version_request);
+	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
+	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN10;
+	version_req.is_last_attempt = 1;
+	dm_device.version = version_req.version.version;
+
+	ret = vmbus_sendpacket(dev->channel, &version_req,
+			       sizeof(struct dm_version_request),
+			       (unsigned long)NULL, VM_PKT_DATA_INBAND, 0);
+	if (ret)
+		goto out;
+
+	t = wait_for_completion_timeout(&dm_device.host_event, secs_to_jiffies(5));
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	/*
+	 * If we could not negotiate a compatible version with the host
+	 * fail the probe function.
+	 */
+	if (dm_device.state == DM_INIT_ERROR) {
+		ret = -EPROTO;
+		goto out;
+	}
+
+	pr_info("Using Dynamic Memory protocol version %u.%u\n",
+		DYNMEM_MAJOR_VERSION(dm_device.version),
+		DYNMEM_MINOR_VERSION(dm_device.version));
+
+	/*
+	 * Now submit our capabilities to the host.
+	 */
+	memset(&cap_msg, 0, sizeof(struct dm_capabilities));
+	cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
+	cap_msg.hdr.size = sizeof(struct dm_capabilities);
+	cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);
+
+	/*
+	 * When hibernation (i.e. virtual ACPI S4 state) is enabled, the host
+	 * currently still requires the bits to be set, so we have to add code
+	 * to fail the host's hot-add and balloon up/down requests, if any.
+	 */
+	cap_msg.caps.cap_bits.balloon = ballooning_enabled();
+	cap_msg.caps.cap_bits.hot_add = hot_add_enabled();
+
+	/*
+	 * Specify our alignment requirements for memory hot-add. The value is
+	 * the log base 2 of the number of megabytes in a chunk. For example,
+	 * with 256 MiB chunks, the value is 8. The number of MiB in a chunk
+	 * must be a power of 2.
+	 */
+	cap_msg.caps.cap_bits.hot_add_alignment =
+					ilog2(HA_BYTES_IN_CHUNK / SZ_1M);
+
+	/*
+	 * Currently the host does not use these
+	 * values and we set them to what is done in the
+	 * Windows driver.
+	 */
+	cap_msg.min_page_cnt = 0;
+	cap_msg.max_page_number = -1;
+
+	ret = vmbus_sendpacket(dev->channel, &cap_msg,
+			       sizeof(struct dm_capabilities),
+			       (unsigned long)NULL, VM_PKT_DATA_INBAND, 0);
+	if (ret)
+		goto out;
+
+	t = wait_for_completion_timeout(&dm_device.host_event, secs_to_jiffies(5));
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	/*
+	 * If the host does not like our capabilities,
+	 * fail the probe function.
+	 */
+	if (dm_device.state == DM_INIT_ERROR) {
+		ret = -EPROTO;
+		goto out;
+	}
+
+	return 0;
+out:
+	vmbus_close(dev->channel);
+	return ret;
+}
+
+/*
+ * DEBUGFS Interface
+ */
+#ifdef CONFIG_DEBUG_FS
+
+/**
+ * hv_balloon_debug_show - shows statistics of balloon operations.
+ * @f: pointer to the &struct seq_file.
+ * @offset: ignored.
+ *
+ * Provides the statistics that can be accessed in hv-balloon in the debugfs.
+ *
+ * Return: zero on success or an error code.
+ */
+static int hv_balloon_debug_show(struct seq_file *f, void *offset)
+{
+	struct hv_dynmem_device *dm = f->private;
+	char *sname;
+
+	seq_printf(f, "%-22s: %u.%u\n", "host_version",
+			DYNMEM_MAJOR_VERSION(dm->version),
+			DYNMEM_MINOR_VERSION(dm->version));
+
+	seq_printf(f, "%-22s:", "capabilities");
+	if (ballooning_enabled())
+		seq_puts(f, " enabled");
+
+	if (hot_add_enabled())
+		seq_puts(f, " hot_add");
+
+	seq_printf(f, "\n%-22s: %u", "state", dm->state);
+	switch (dm->state) {
+	case DM_INITIALIZING:
+			sname = "Initializing";
+			break;
+	case DM_INITIALIZED:
+			sname = "Initialized";
+			break;
+	case DM_BALLOON_UP:
+			sname = "Balloon Up";
+			break;
+	case DM_BALLOON_DOWN:
+			sname = "Balloon Down";
+			break;
+	case DM_HOT_ADD:
+			sname = "Hot Add";
+			break;
+	case DM_INIT_ERROR:
+			sname = "Error";
+			break;
+	default:
+			sname = "Unknown";
+	}
+	seq_printf(f, " (%s)\n", sname);
+
+	/* HV Page Size */
+	seq_printf(f, "%-22s: %ld\n", "page_size", HV_HYP_PAGE_SIZE);
+
+	/* Pages added with hot_add */
+	seq_printf(f, "%-22s: %u\n", "pages_added", dm->num_pages_added);
+
+	/* pages that are "onlined"/used from pages_added */
+	seq_printf(f, "%-22s: %u\n", "pages_onlined", dm->num_pages_onlined);
+
+	/* pages we have given back to host */
+	seq_printf(f, "%-22s: %u\n", "pages_ballooned", dm->num_pages_ballooned);
+
+	seq_printf(f, "%-22s: %lu\n", "total_pages_committed",
+		   get_pages_committed(dm));
+
+	seq_printf(f, "%-22s: %llu\n", "max_dynamic_page_count",
+		   dm->max_dynamic_page_count);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(hv_balloon_debug);
+
+static void  hv_balloon_debugfs_init(struct hv_dynmem_device *b)
+{
+	debugfs_create_file("hv-balloon", 0444, NULL, b,
+			    &hv_balloon_debug_fops);
+}
+
+static void  hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
+{
+	debugfs_lookup_and_remove("hv-balloon", NULL);
+}
+
+#else
+
+static inline void hv_balloon_debugfs_init(struct hv_dynmem_device  *b)
+{
+}
+
+static inline void hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
+{
+}
+
+#endif	/* CONFIG_DEBUG_FS */
+
+static int balloon_probe(struct hv_device *dev,
+			 const struct hv_vmbus_device_id *dev_id)
+{
+	int ret;
+
+	allow_hibernation = hv_is_hibernation_supported();
+	if (allow_hibernation)
+		hot_add = false;
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+	/*
+	 * Hot-add must operate in chunks that are of size equal to the
+	 * memory block size because that's what the core add_memory()
+	 * interface requires. The Hyper-V interface requires that the memory
+	 * block size be a power of 2, which is guaranteed by the check in
+	 * memory_dev_init().
+	 */
+	ha_pages_in_chunk = memory_block_size_bytes() / PAGE_SIZE;
+	do_hot_add = hot_add;
+#else
+	/*
+	 * Without MEMORY_HOTPLUG, the guest returns a failure status for all
+	 * hot add requests from Hyper-V, and the chunk size is used only to
+	 * specify alignment to Hyper-V as required by the host/guest protocol.
+	 * Somewhat arbitrarily, use 128 MiB.
+	 */
+	ha_pages_in_chunk = SZ_128M / PAGE_SIZE;
+	do_hot_add = false;
+#endif
+	dm_device.dev = dev;
+	dm_device.state = DM_INITIALIZING;
+	dm_device.next_version = 0;
+	init_completion(&dm_device.host_event);
+	init_completion(&dm_device.config_event);
+	INIT_LIST_HEAD(&dm_device.ha_region_list);
+	spin_lock_init(&dm_device.ha_lock);
+	INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
+	INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
+	dm_device.host_specified_ha_region = false;
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+	set_online_page_callback(&hv_online_page);
+	init_completion(&dm_device.ol_waitevent);
+	register_memory_notifier(&hv_memory_nb);
+#endif
+
+	hv_set_drvdata(dev, &dm_device);
+
+	ret = balloon_connect_vsp(dev);
+	if (ret != 0)
+		goto connect_error;
+
+	enable_page_reporting();
+	dm_device.state = DM_INITIALIZED;
+
+	dm_device.thread =
+		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
+	if (IS_ERR(dm_device.thread)) {
+		ret = PTR_ERR(dm_device.thread);
+		goto probe_error;
+	}
+
+	hv_balloon_debugfs_init(&dm_device);
+
+	return 0;
+
+probe_error:
+	dm_device.state = DM_INIT_ERROR;
+	dm_device.thread  = NULL;
+	disable_page_reporting();
+	vmbus_close(dev->channel);
+connect_error:
+#ifdef CONFIG_MEMORY_HOTPLUG
+	unregister_memory_notifier(&hv_memory_nb);
+	restore_online_page_callback(&hv_online_page);
+#endif
+	return ret;
+}
+
+static void balloon_remove(struct hv_device *dev)
+{
+	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
+	struct hv_hotadd_state *has, *tmp;
+	struct hv_hotadd_gap *gap, *tmp_gap;
+
+	if (dm->num_pages_ballooned != 0)
+		pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
+
+	hv_balloon_debugfs_exit(dm);
+
+	cancel_work_sync(&dm->balloon_wrk.wrk);
+	cancel_work_sync(&dm->ha_wrk.wrk);
+
+	kthread_stop(dm->thread);
+
+	/*
+	 * This is to handle the case when balloon_resume()
+	 * call has failed and some cleanup has been done as
+	 * a part of the error handling.
+	 */
+	if (dm_device.state != DM_INIT_ERROR) {
+		disable_page_reporting();
+		vmbus_close(dev->channel);
+#ifdef CONFIG_MEMORY_HOTPLUG
+		unregister_memory_notifier(&hv_memory_nb);
+		restore_online_page_callback(&hv_online_page);
+#endif
+	}
+
+	guard(spinlock_irqsave)(&dm_device.ha_lock);
+	list_for_each_entry_safe(has, tmp, &dm->ha_region_list, list) {
+		list_for_each_entry_safe(gap, tmp_gap, &has->gap_list, list) {
+			list_del(&gap->list);
+			kfree(gap);
+		}
+		list_del(&has->list);
+		kfree(has);
+	}
+}
+
+static int balloon_suspend(struct hv_device *hv_dev)
+{
+	struct hv_dynmem_device *dm = hv_get_drvdata(hv_dev);
+
+	tasklet_disable(&hv_dev->channel->callback_event);
+
+	cancel_work_sync(&dm->balloon_wrk.wrk);
+	cancel_work_sync(&dm->ha_wrk.wrk);
+
+	if (dm->thread) {
+		kthread_stop(dm->thread);
+		dm->thread = NULL;
+		vmbus_close(hv_dev->channel);
+	}
+
+	tasklet_enable(&hv_dev->channel->callback_event);
+
+	return 0;
+}
+
+static int balloon_resume(struct hv_device *dev)
+{
+	int ret;
+
+	dm_device.state = DM_INITIALIZING;
+
+	ret = balloon_connect_vsp(dev);
+
+	if (ret != 0)
+		goto out;
+
+	dm_device.thread =
+		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
+	if (IS_ERR(dm_device.thread)) {
+		ret = PTR_ERR(dm_device.thread);
+		dm_device.thread = NULL;
+		goto close_channel;
+	}
+
+	dm_device.state = DM_INITIALIZED;
+	return 0;
+close_channel:
+	vmbus_close(dev->channel);
+out:
+	dm_device.state = DM_INIT_ERROR;
+	disable_page_reporting();
+#ifdef CONFIG_MEMORY_HOTPLUG
+	unregister_memory_notifier(&hv_memory_nb);
+	restore_online_page_callback(&hv_online_page);
+#endif
+	return ret;
+}
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Dynamic Memory Class ID */
+	/* 525074DC-8985-46e2-8057-A307DC18A502 */
+	{ HV_DM_GUID, },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+static  struct hv_driver balloon_drv = {
+	.name = "hv_balloon",
+	.id_table = id_table,
+	.probe =  balloon_probe,
+	.remove =  balloon_remove,
+	.suspend = balloon_suspend,
+	.resume = balloon_resume,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+
+static int __init init_balloon_drv(void)
+{
+	return vmbus_driver_register(&balloon_drv);
+}
+
+module_init(init_balloon_drv);
+
+MODULE_DESCRIPTION("Hyper-V Balloon");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
new file mode 100644
index 000000000..31256cb22
--- /dev/null
+++ b/drivers/hv/hv_common.c
@@ -0,0 +1,863 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Architecture neutral utility routines for interacting with
+ * Hyper-V. This file is specifically for code that must be
+ * built-in to the kernel image when CONFIG_HYPERV is set
+ * (vs. being in a module) because it is called from architecture
+ * specific code under arch/.
+ *
+ * Copyright (C) 2021, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/types.h>
+#include <linux/acpi.h>
+#include <linux/export.h>
+#include <linux/bitfield.h>
+#include <linux/cpumask.h>
+#include <linux/sched/task_stack.h>
+#include <linux/panic_notifier.h>
+#include <linux/ptrace.h>
+#include <linux/random.h>
+#include <linux/efi.h>
+#include <linux/kdebug.h>
+#include <linux/kmsg_dump.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/dma-map-ops.h>
+#include <linux/set_memory.h>
+#include <hyperv/hvhdk.h>
+#include <asm/mshyperv.h>
+
+u64 hv_current_partition_id = HV_PARTITION_ID_SELF;
+EXPORT_SYMBOL_GPL(hv_current_partition_id);
+
+enum hv_partition_type hv_curr_partition_type;
+EXPORT_SYMBOL_GPL(hv_curr_partition_type);
+
+/*
+ * ms_hyperv and hv_nested are defined here with other
+ * Hyper-V specific globals so they are shared across all architectures and are
+ * built only when CONFIG_HYPERV is defined.  But on x86,
+ * ms_hyperv_init_platform() is built even when CONFIG_HYPERV is not
+ * defined, and it uses these three variables.  So mark them as __weak
+ * here, allowing for an overriding definition in the module containing
+ * ms_hyperv_init_platform().
+ */
+bool __weak hv_nested;
+EXPORT_SYMBOL_GPL(hv_nested);
+
+struct ms_hyperv_info __weak ms_hyperv;
+EXPORT_SYMBOL_GPL(ms_hyperv);
+
+u32 *hv_vp_index;
+EXPORT_SYMBOL_GPL(hv_vp_index);
+
+u32 hv_max_vp_index;
+EXPORT_SYMBOL_GPL(hv_max_vp_index);
+
+void * __percpu *hyperv_pcpu_input_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
+
+void * __percpu *hyperv_pcpu_output_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
+
+static void hv_kmsg_dump_unregister(void);
+
+static struct ctl_table_header *hv_ctl_table_hdr;
+
+/*
+ * Per-cpu array holding the tail pointer for the SynIC event ring buffer
+ * for each SINT.
+ *
+ * We cannot maintain this in mshv driver because the tail pointer should
+ * persist even if the mshv driver is unloaded.
+ */
+u8 * __percpu *hv_synic_eventring_tail;
+EXPORT_SYMBOL_GPL(hv_synic_eventring_tail);
+
+/*
+ * Hyper-V specific initialization and shutdown code that is
+ * common across all architectures.  Called from architecture
+ * specific initialization functions.
+ */
+
+void __init hv_common_free(void)
+{
+	unregister_sysctl_table(hv_ctl_table_hdr);
+	hv_ctl_table_hdr = NULL;
+
+	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
+		hv_kmsg_dump_unregister();
+
+	kfree(hv_vp_index);
+	hv_vp_index = NULL;
+
+	free_percpu(hyperv_pcpu_output_arg);
+	hyperv_pcpu_output_arg = NULL;
+
+	free_percpu(hyperv_pcpu_input_arg);
+	hyperv_pcpu_input_arg = NULL;
+
+	free_percpu(hv_synic_eventring_tail);
+	hv_synic_eventring_tail = NULL;
+}
+
+static void *hv_panic_page;
+
+/*
+ * Boolean to control whether to report panic messages over Hyper-V.
+ *
+ * It can be set via /proc/sys/kernel/hyperv_record_panic_msg
+ */
+static int sysctl_record_panic_msg = 1;
+
+/*
+ * sysctl option to allow the user to control whether kmsg data should be
+ * reported to Hyper-V on panic.
+ */
+static const struct ctl_table hv_ctl_table[] = {
+	{
+		.procname	= "hyperv_record_panic_msg",
+		.data		= &sysctl_record_panic_msg,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE
+	},
+};
+
+static int hv_die_panic_notify_crash(struct notifier_block *self,
+				     unsigned long val, void *args);
+
+static struct notifier_block hyperv_die_report_block = {
+	.notifier_call = hv_die_panic_notify_crash,
+};
+
+static struct notifier_block hyperv_panic_report_block = {
+	.notifier_call = hv_die_panic_notify_crash,
+};
+
+/*
+ * The following callback works both as die and panic notifier; its
+ * goal is to provide panic information to the hypervisor unless the
+ * kmsg dumper is used [see hv_kmsg_dump()], which provides more
+ * information but isn't always available.
+ *
+ * Notice that both the panic/die report notifiers are registered only
+ * if we have the capability HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE set.
+ */
+static int hv_die_panic_notify_crash(struct notifier_block *self,
+				     unsigned long val, void *args)
+{
+	struct pt_regs *regs;
+	bool is_die;
+
+	/* Don't notify Hyper-V unless we have a die oops event or panic. */
+	if (self == &hyperv_panic_report_block) {
+		is_die = false;
+		regs = current_pt_regs();
+	} else { /* die event */
+		if (val != DIE_OOPS)
+			return NOTIFY_DONE;
+
+		is_die = true;
+		regs = ((struct die_args *)args)->regs;
+	}
+
+	/*
+	 * Hyper-V should be notified only once about a panic/die. If we will
+	 * be calling hv_kmsg_dump() later with kmsg data, don't do the
+	 * notification here.
+	 */
+	if (!sysctl_record_panic_msg || !hv_panic_page)
+		hyperv_report_panic(regs, val, is_die);
+
+	return NOTIFY_DONE;
+}
+
+/*
+ * Callback from kmsg_dump. Grab as much as possible from the end of the kmsg
+ * buffer and call into Hyper-V to transfer the data.
+ */
+static void hv_kmsg_dump(struct kmsg_dumper *dumper,
+			 struct kmsg_dump_detail *detail)
+{
+	struct kmsg_dump_iter iter;
+	size_t bytes_written;
+
+	/* We are only interested in panics. */
+	if (detail->reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
+		return;
+
+	/*
+	 * Write dump contents to the page. No need to synchronize; panic should
+	 * be single-threaded. Ignore failures from kmsg_dump_get_buffer() since
+	 * panic notification should be done even if there is no message data.
+	 * Don't assume bytes_written is set in case of failure, so initialize it.
+	 */
+	kmsg_dump_rewind(&iter);
+	bytes_written = 0;
+	(void)kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
+			     &bytes_written);
+
+	/*
+	 * P3 to contain the physical address of the panic page & P4 to
+	 * contain the size of the panic data in that page. Rest of the
+	 * registers are no-op when the NOTIFY_MSG flag is set.
+	 */
+	hv_set_msr(HV_MSR_CRASH_P0, 0);
+	hv_set_msr(HV_MSR_CRASH_P1, 0);
+	hv_set_msr(HV_MSR_CRASH_P2, 0);
+	hv_set_msr(HV_MSR_CRASH_P3, bytes_written ? virt_to_phys(hv_panic_page) : 0);
+	hv_set_msr(HV_MSR_CRASH_P4, bytes_written);
+
+	/*
+	 * Let Hyper-V know there is crash data available along with
+	 * the panic message.
+	 */
+	hv_set_msr(HV_MSR_CRASH_CTL,
+		   (HV_CRASH_CTL_CRASH_NOTIFY |
+		    HV_CRASH_CTL_CRASH_NOTIFY_MSG));
+}
+
+static struct kmsg_dumper hv_kmsg_dumper = {
+	.dump = hv_kmsg_dump,
+};
+
+static void hv_kmsg_dump_unregister(void)
+{
+	kmsg_dump_unregister(&hv_kmsg_dumper);
+	unregister_die_notifier(&hyperv_die_report_block);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &hyperv_panic_report_block);
+
+	kfree(hv_panic_page);
+	hv_panic_page = NULL;
+}
+
+static void hv_kmsg_dump_register(void)
+{
+	int ret;
+
+	hv_panic_page = kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+	if (!hv_panic_page) {
+		pr_err("Hyper-V: panic message page memory allocation failed\n");
+		return;
+	}
+
+	ret = kmsg_dump_register(&hv_kmsg_dumper);
+	if (ret) {
+		pr_err("Hyper-V: kmsg dump register error 0x%x\n", ret);
+		kfree(hv_panic_page);
+		hv_panic_page = NULL;
+	}
+}
+
+static inline bool hv_output_page_exists(void)
+{
+	return hv_parent_partition() || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
+}
+
+void __init hv_get_partition_id(void)
+{
+	struct hv_output_get_partition_id *output;
+	unsigned long flags;
+	u64 status, pt_id;
+
+	local_irq_save(flags);
+	output = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output);
+	pt_id = output->partition_id;
+	local_irq_restore(flags);
+
+	if (hv_result_success(status))
+		hv_current_partition_id = pt_id;
+	else
+		pr_err("Hyper-V: failed to get partition ID: %#x\n",
+		       hv_result(status));
+}
+#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
+u8 __init get_vtl(void)
+{
+	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
+	struct hv_input_get_vp_registers *input;
+	struct hv_output_get_vp_registers *output;
+	unsigned long flags;
+	u64 ret;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	memset(input, 0, struct_size(input, names, 1));
+	input->partition_id = HV_PARTITION_ID_SELF;
+	input->vp_index = HV_VP_INDEX_SELF;
+	input->input_vtl.as_uint8 = 0;
+	input->names[0] = HV_REGISTER_VSM_VP_STATUS;
+
+	ret = hv_do_hypercall(control, input, output);
+	if (hv_result_success(ret)) {
+		ret = output->values[0].reg8 & HV_VTL_MASK;
+	} else {
+		pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
+		BUG();
+	}
+
+	local_irq_restore(flags);
+	return ret;
+}
+#endif
+
+int __init hv_common_init(void)
+{
+	int i;
+	union hv_hypervisor_version_info version;
+
+	/* Get information about the Microsoft Hypervisor version */
+	if (!hv_get_hypervisor_version(&version))
+		pr_info("Hyper-V: Hypervisor Build %d.%d.%d.%d-%d-%d\n",
+			version.major_version, version.minor_version,
+			version.build_number, version.service_number,
+			version.service_pack, version.service_branch);
+
+	if (hv_is_isolation_supported())
+		sysctl_record_panic_msg = 0;
+
+	/*
+	 * Hyper-V expects to get crash register data or kmsg when
+	 * crash enlightment is available and system crashes. Set
+	 * crash_kexec_post_notifiers to be true to make sure that
+	 * calling crash enlightment interface before running kdump
+	 * kernel.
+	 */
+	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
+		u64 hyperv_crash_ctl;
+
+		crash_kexec_post_notifiers = true;
+		pr_info("Hyper-V: enabling crash_kexec_post_notifiers\n");
+
+		/*
+		 * Panic message recording (sysctl_record_panic_msg)
+		 * is enabled by default in non-isolated guests and
+		 * disabled by default in isolated guests; the panic
+		 * message recording won't be available in isolated
+		 * guests should the following registration fail.
+		 */
+		hv_ctl_table_hdr = register_sysctl("kernel", hv_ctl_table);
+		if (!hv_ctl_table_hdr)
+			pr_err("Hyper-V: sysctl table register error");
+
+		/*
+		 * Register for panic kmsg callback only if the right
+		 * capability is supported by the hypervisor.
+		 */
+		hyperv_crash_ctl = hv_get_msr(HV_MSR_CRASH_CTL);
+		if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG)
+			hv_kmsg_dump_register();
+
+		register_die_notifier(&hyperv_die_report_block);
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &hyperv_panic_report_block);
+	}
+
+	/*
+	 * Allocate the per-CPU state for the hypercall input arg.
+	 * If this allocation fails, we will not be able to setup
+	 * (per-CPU) hypercall input page and thus this failure is
+	 * fatal on Hyper-V.
+	 */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+	BUG_ON(!hyperv_pcpu_input_arg);
+
+	/* Allocate the per-CPU state for output arg for root */
+	if (hv_output_page_exists()) {
+		hyperv_pcpu_output_arg = alloc_percpu(void *);
+		BUG_ON(!hyperv_pcpu_output_arg);
+	}
+
+	if (hv_parent_partition()) {
+		hv_synic_eventring_tail = alloc_percpu(u8 *);
+		BUG_ON(!hv_synic_eventring_tail);
+	}
+
+	hv_vp_index = kmalloc_array(nr_cpu_ids, sizeof(*hv_vp_index),
+				    GFP_KERNEL);
+	if (!hv_vp_index) {
+		hv_common_free();
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < nr_cpu_ids; i++)
+		hv_vp_index[i] = VP_INVAL;
+
+	return 0;
+}
+
+void __init ms_hyperv_late_init(void)
+{
+	struct acpi_table_header *header;
+	acpi_status status;
+	u8 *randomdata;
+	u32 length, i;
+
+	/*
+	 * Seed the Linux random number generator with entropy provided by
+	 * the Hyper-V host in ACPI table OEM0.
+	 */
+	if (!IS_ENABLED(CONFIG_ACPI))
+		return;
+
+	status = acpi_get_table("OEM0", 0, &header);
+	if (ACPI_FAILURE(status) || !header)
+		return;
+
+	/*
+	 * Since the "OEM0" table name is for OEM specific usage, verify
+	 * that what we're seeing purports to be from Microsoft.
+	 */
+	if (strncmp(header->oem_table_id, "MICROSFT", 8))
+		goto error;
+
+	/*
+	 * Ensure the length is reasonable. Requiring at least 8 bytes and
+	 * no more than 4K bytes is somewhat arbitrary and just protects
+	 * against a malformed table. Hyper-V currently provides 64 bytes,
+	 * but allow for a change in a later version.
+	 */
+	if (header->length < sizeof(*header) + 8 ||
+	    header->length > sizeof(*header) + SZ_4K)
+		goto error;
+
+	length = header->length - sizeof(*header);
+	randomdata = (u8 *)(header + 1);
+
+	pr_debug("Hyper-V: Seeding rng with %d random bytes from ACPI table OEM0\n",
+			length);
+
+	add_bootloader_randomness(randomdata, length);
+
+	/*
+	 * To prevent the seed data from being visible in /sys/firmware/acpi,
+	 * zero out the random data in the ACPI table and fixup the checksum.
+	 * The zero'ing is done out of an abundance of caution in avoiding
+	 * potential security risks to the rng. Similarly, reset the table
+	 * length to just the header size so that a subsequent kexec doesn't
+	 * try to use the zero'ed out random data.
+	 */
+	for (i = 0; i < length; i++) {
+		header->checksum += randomdata[i];
+		randomdata[i] = 0;
+	}
+
+	for (i = 0; i < sizeof(header->length); i++)
+		header->checksum += ((u8 *)&header->length)[i];
+	header->length = sizeof(*header);
+	for (i = 0; i < sizeof(header->length); i++)
+		header->checksum -= ((u8 *)&header->length)[i];
+
+error:
+	acpi_put_table(header);
+}
+
+/*
+ * Hyper-V specific initialization and die code for
+ * individual CPUs that is common across all architectures.
+ * Called by the CPU hotplug mechanism.
+ */
+
+int hv_common_cpu_init(unsigned int cpu)
+{
+	void **inputarg, **outputarg;
+	u8 **synic_eventring_tail;
+	u64 msr_vp_index;
+	gfp_t flags;
+	const int pgcount = hv_output_page_exists() ? 2 : 1;
+	void *mem;
+	int ret = 0;
+
+	/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
+	flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
+
+	inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	/*
+	 * The per-cpu memory is already allocated if this CPU was previously
+	 * online and then taken offline
+	 */
+	if (!*inputarg) {
+		mem = kmalloc_array(pgcount, HV_HYP_PAGE_SIZE, flags);
+		if (!mem)
+			return -ENOMEM;
+
+		if (hv_output_page_exists()) {
+			outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
+			*outputarg = (char *)mem + HV_HYP_PAGE_SIZE;
+		}
+
+		if (!ms_hyperv.paravisor_present &&
+		    (hv_isolation_type_snp() || hv_isolation_type_tdx())) {
+			ret = set_memory_decrypted((unsigned long)mem, pgcount);
+			if (ret) {
+				/* It may be unsafe to free 'mem' */
+				return ret;
+			}
+
+			memset(mem, 0x00, pgcount * HV_HYP_PAGE_SIZE);
+		}
+
+		/*
+		 * In a fully enlightened TDX/SNP VM with more than 64 VPs, if
+		 * hyperv_pcpu_input_arg is not NULL, set_memory_decrypted() ->
+		 * ... -> cpa_flush()-> ... -> __send_ipi_mask_ex() tries to
+		 * use hyperv_pcpu_input_arg as the hypercall input page, which
+		 * must be a decrypted page in such a VM, but the page is still
+		 * encrypted before set_memory_decrypted() returns. Fix this by
+		 * setting *inputarg after the above set_memory_decrypted(): if
+		 * hyperv_pcpu_input_arg is NULL, __send_ipi_mask_ex() returns
+		 * HV_STATUS_INVALID_PARAMETER immediately, and the function
+		 * hv_send_ipi_mask() falls back to orig_apic.send_IPI_mask(),
+		 * which may be slightly slower than the hypercall, but still
+		 * works correctly in such a VM.
+		 */
+		*inputarg = mem;
+	}
+
+	msr_vp_index = hv_get_msr(HV_MSR_VP_INDEX);
+
+	hv_vp_index[cpu] = msr_vp_index;
+
+	if (msr_vp_index > hv_max_vp_index)
+		hv_max_vp_index = msr_vp_index;
+
+	if (hv_parent_partition()) {
+		synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
+		*synic_eventring_tail = kcalloc(HV_SYNIC_SINT_COUNT,
+						sizeof(u8), flags);
+		/* No need to unwind any of the above on failure here */
+		if (unlikely(!*synic_eventring_tail))
+			ret = -ENOMEM;
+	}
+
+	return ret;
+}
+
+int hv_common_cpu_die(unsigned int cpu)
+{
+	u8 **synic_eventring_tail;
+	/*
+	 * The hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory
+	 * is not freed when the CPU goes offline as the hyperv_pcpu_input_arg
+	 * may be used by the Hyper-V vPCI driver in reassigning interrupts
+	 * as part of the offlining process.  The interrupt reassignment
+	 * happens *after* the CPUHP_AP_HYPERV_ONLINE state has run and
+	 * called this function.
+	 *
+	 * If a previously offlined CPU is brought back online again, the
+	 * originally allocated memory is reused in hv_common_cpu_init().
+	 */
+
+	if (hv_parent_partition()) {
+		synic_eventring_tail = this_cpu_ptr(hv_synic_eventring_tail);
+		kfree(*synic_eventring_tail);
+		*synic_eventring_tail = NULL;
+	}
+
+	return 0;
+}
+
+/* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
+bool hv_query_ext_cap(u64 cap_query)
+{
+	/*
+	 * The address of the 'hv_extended_cap' variable will be used as an
+	 * output parameter to the hypercall below and so it should be
+	 * compatible with 'virt_to_phys'. Which means, it's address should be
+	 * directly mapped. Use 'static' to keep it compatible; stack variables
+	 * can be virtually mapped, making them incompatible with
+	 * 'virt_to_phys'.
+	 * Hypercall input/output addresses should also be 8-byte aligned.
+	 */
+	static u64 hv_extended_cap __aligned(8);
+	static bool hv_extended_cap_queried;
+	u64 status;
+
+	/*
+	 * Querying extended capabilities is an extended hypercall. Check if the
+	 * partition supports extended hypercall, first.
+	 */
+	if (!(ms_hyperv.priv_high & HV_ENABLE_EXTENDED_HYPERCALLS))
+		return false;
+
+	/* Extended capabilities do not change at runtime. */
+	if (hv_extended_cap_queried)
+		return hv_extended_cap & cap_query;
+
+	status = hv_do_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, NULL,
+				 &hv_extended_cap);
+
+	/*
+	 * The query extended capabilities hypercall should not fail under
+	 * any normal circumstances. Avoid repeatedly making the hypercall, on
+	 * error.
+	 */
+	hv_extended_cap_queried = true;
+	if (!hv_result_success(status)) {
+		pr_err("Hyper-V: Extended query capabilities hypercall failed 0x%llx\n",
+		       status);
+		return false;
+	}
+
+	return hv_extended_cap & cap_query;
+}
+EXPORT_SYMBOL_GPL(hv_query_ext_cap);
+
+void hv_setup_dma_ops(struct device *dev, bool coherent)
+{
+	arch_setup_dma_ops(dev, coherent);
+}
+EXPORT_SYMBOL_GPL(hv_setup_dma_ops);
+
+bool hv_is_hibernation_supported(void)
+{
+	return !hv_root_partition() && acpi_sleep_state_supported(ACPI_STATE_S4);
+}
+EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
+
+/*
+ * Default function to read the Hyper-V reference counter, independent
+ * of whether Hyper-V enlightened clocks/timers are being used. But on
+ * architectures where it is used, Hyper-V enlightenment code in
+ * hyperv_timer.c may override this function.
+ */
+static u64 __hv_read_ref_counter(void)
+{
+	return hv_get_msr(HV_MSR_TIME_REF_COUNT);
+}
+
+u64 (*hv_read_reference_counter)(void) = __hv_read_ref_counter;
+EXPORT_SYMBOL_GPL(hv_read_reference_counter);
+
+/* These __weak functions provide default "no-op" behavior and
+ * may be overridden by architecture specific versions. Architectures
+ * for which the default "no-op" behavior is sufficient can leave
+ * them unimplemented and not be cluttered with a bunch of stub
+ * functions in arch-specific code.
+ */
+
+bool __weak hv_is_isolation_supported(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
+
+bool __weak hv_isolation_type_snp(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
+
+bool __weak hv_isolation_type_tdx(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
+
+void __weak hv_setup_vmbus_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
+
+void __weak hv_remove_vmbus_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
+
+void __weak hv_setup_mshv_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_mshv_handler);
+
+void __weak hv_setup_kexec_handler(void (*handler)(void))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
+
+void __weak hv_remove_kexec_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
+
+void __weak hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
+{
+}
+EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
+
+void __weak hv_remove_crash_handler(void)
+{
+}
+EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
+
+void __weak hyperv_cleanup(void)
+{
+}
+EXPORT_SYMBOL_GPL(hyperv_cleanup);
+
+u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
+{
+	return HV_STATUS_INVALID_PARAMETER;
+}
+EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
+
+u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
+{
+	return HV_STATUS_INVALID_PARAMETER;
+}
+EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
+
+void __weak hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool set)
+{
+}
+EXPORT_SYMBOL_GPL(hv_enable_coco_interrupt);
+
+void __weak hv_para_set_sint_proxy(bool enable)
+{
+}
+EXPORT_SYMBOL_GPL(hv_para_set_sint_proxy);
+
+u64 __weak hv_para_get_synic_register(unsigned int reg)
+{
+	return ~0ULL;
+}
+EXPORT_SYMBOL_GPL(hv_para_get_synic_register);
+
+void __weak hv_para_set_synic_register(unsigned int reg, u64 val)
+{
+}
+EXPORT_SYMBOL_GPL(hv_para_set_synic_register);
+
+void hv_identify_partition_type(void)
+{
+	/* Assume guest role */
+	hv_curr_partition_type = HV_PARTITION_TYPE_GUEST;
+	/*
+	 * Check partition creation and cpu management privileges
+	 *
+	 * Hyper-V should never specify running as root and as a Confidential
+	 * VM. But to protect against a compromised/malicious Hyper-V trying
+	 * to exploit root behavior to expose Confidential VM memory, ignore
+	 * the root partition setting if also a Confidential VM.
+	 */
+	if ((ms_hyperv.priv_high & HV_CREATE_PARTITIONS) &&
+	    !(ms_hyperv.priv_high & HV_ISOLATION)) {
+
+		if (!IS_ENABLED(CONFIG_MSHV_ROOT)) {
+			pr_crit("Hyper-V: CONFIG_MSHV_ROOT not enabled!\n");
+		} else if (ms_hyperv.priv_high & HV_CPU_MANAGEMENT) {
+			pr_info("Hyper-V: running as root partition\n");
+			hv_curr_partition_type = HV_PARTITION_TYPE_ROOT;
+		} else {
+			pr_info("Hyper-V: running as L1VH partition\n");
+			hv_curr_partition_type = HV_PARTITION_TYPE_L1VH;
+		}
+	}
+}
+
+struct hv_status_info {
+	char *string;
+	int errno;
+	u16 code;
+};
+
+/*
+ * Note on the errno mappings:
+ * A failed hypercall is usually only recoverable (or loggable) near
+ * the call site where the HV_STATUS_* code is known. So the errno
+ * it gets converted to is not too useful further up the stack.
+ * Provide a few mappings that could be useful, and revert to -EIO
+ * as a fallback.
+ */
+static const struct hv_status_info hv_status_infos[] = {
+#define _STATUS_INFO(status, errno) { #status, (errno), (status) }
+	_STATUS_INFO(HV_STATUS_SUCCESS,				0),
+	_STATUS_INFO(HV_STATUS_INVALID_HYPERCALL_CODE,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_HYPERCALL_INPUT,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_ALIGNMENT,		-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_PARAMETER,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_ACCESS_DENIED,			-EACCES),
+	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_STATE,		-EIO),
+	_STATUS_INFO(HV_STATUS_OPERATION_DENIED,		-EACCES),
+	_STATUS_INFO(HV_STATUS_UNKNOWN_PROPERTY,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_PROPERTY_VALUE_OUT_OF_RANGE,	-EINVAL),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_MEMORY,		-ENOMEM),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY,	-ENOMEM),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_ROOT_MEMORY,	-ENOMEM),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_CONTIGUOUS_ROOT_MEMORY,	-ENOMEM),
+	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_ID,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_VP_INDEX,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_NOT_FOUND,			-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_PORT_ID,			-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_CONNECTION_ID,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INSUFFICIENT_BUFFERS,		-EIO),
+	_STATUS_INFO(HV_STATUS_NOT_ACKNOWLEDGED,		-EIO),
+	_STATUS_INFO(HV_STATUS_INVALID_VP_STATE,		-EIO),
+	_STATUS_INFO(HV_STATUS_NO_RESOURCES,			-EIO),
+	_STATUS_INFO(HV_STATUS_PROCESSOR_FEATURE_NOT_SUPPORTED,	-EOPNOTSUPP),
+	_STATUS_INFO(HV_STATUS_INVALID_LP_INDEX,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_INVALID_REGISTER_VALUE,		-EINVAL),
+	_STATUS_INFO(HV_STATUS_OPERATION_FAILED,		-EIO),
+	_STATUS_INFO(HV_STATUS_TIME_OUT,			-EIO),
+	_STATUS_INFO(HV_STATUS_CALL_PENDING,			-EIO),
+	_STATUS_INFO(HV_STATUS_VTL_ALREADY_ENABLED,		-EIO),
+#undef _STATUS_INFO
+};
+
+static inline const struct hv_status_info *find_hv_status_info(u64 hv_status)
+{
+	int i;
+	u16 code = hv_result(hv_status);
+
+	for (i = 0; i < ARRAY_SIZE(hv_status_infos); ++i) {
+		const struct hv_status_info *info = &hv_status_infos[i];
+
+		if (info->code == code)
+			return info;
+	}
+
+	return NULL;
+}
+
+/* Convert a hypercall result into a linux-friendly error code. */
+int hv_result_to_errno(u64 status)
+{
+	const struct hv_status_info *info;
+
+	/* hv_do_hypercall() may return U64_MAX, hypercalls aren't possible */
+	if (unlikely(status == U64_MAX))
+		return -EOPNOTSUPP;
+
+	info = find_hv_status_info(status);
+	if (info)
+		return info->errno;
+
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(hv_result_to_errno);
+
+const char *hv_result_to_string(u64 status)
+{
+	const struct hv_status_info *info;
+
+	if (unlikely(status == U64_MAX))
+		return "Hypercall page missing!";
+
+	info = find_hv_status_info(status);
+	if (info)
+		return info->string;
+
+	return "Unknown";
+}
+EXPORT_SYMBOL_GPL(hv_result_to_string);
diff --git a/drivers/hv/hv_debugfs.c b/drivers/hv/hv_debugfs.c
new file mode 100644
index 000000000..ccf752b66
--- /dev/null
+++ b/drivers/hv/hv_debugfs.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Authors:
+ *   Branden Bonaby <brandonbonaby94@gmail.com>
+ */
+
+#include <linux/hyperv.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+
+#include "hyperv_vmbus.h"
+
+static struct dentry *hv_debug_root;
+
+static int hv_debugfs_delay_get(void *data, u64 *val)
+{
+	*val = *(u32 *)data;
+	return 0;
+}
+
+static int hv_debugfs_delay_set(void *data, u64 val)
+{
+	if (val > 1000)
+		return -EINVAL;
+	*(u32 *)data = val;
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(hv_debugfs_delay_fops, hv_debugfs_delay_get,
+			 hv_debugfs_delay_set, "%llu\n");
+
+static int hv_debugfs_state_get(void *data, u64 *val)
+{
+	*val = *(bool *)data;
+	return 0;
+}
+
+static int hv_debugfs_state_set(void *data, u64 val)
+{
+	if (val == 1)
+		*(bool *)data = true;
+	else if (val == 0)
+		*(bool *)data = false;
+	else
+		return -EINVAL;
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(hv_debugfs_state_fops, hv_debugfs_state_get,
+			 hv_debugfs_state_set, "%llu\n");
+
+/* Setup delay files to store test values */
+static int hv_debug_delay_files(struct hv_device *dev, struct dentry *root)
+{
+	struct vmbus_channel *channel = dev->channel;
+	char *buffer = "fuzz_test_buffer_interrupt_delay";
+	char *message = "fuzz_test_message_delay";
+	int *buffer_val = &channel->fuzz_testing_interrupt_delay;
+	int *message_val = &channel->fuzz_testing_message_delay;
+	struct dentry *buffer_file, *message_file;
+
+	buffer_file = debugfs_create_file(buffer, 0644, root,
+					  buffer_val,
+					  &hv_debugfs_delay_fops);
+	if (IS_ERR(buffer_file)) {
+		pr_debug("debugfs_hyperv: file %s not created\n", buffer);
+		return PTR_ERR(buffer_file);
+	}
+
+	message_file = debugfs_create_file(message, 0644, root,
+					   message_val,
+					   &hv_debugfs_delay_fops);
+	if (IS_ERR(message_file)) {
+		pr_debug("debugfs_hyperv: file %s not created\n", message);
+		return PTR_ERR(message_file);
+	}
+
+	return 0;
+}
+
+/* Setup test state value for vmbus device */
+static int hv_debug_set_test_state(struct hv_device *dev, struct dentry *root)
+{
+	struct vmbus_channel *channel = dev->channel;
+	bool *state = &channel->fuzz_testing_state;
+	char *status = "fuzz_test_state";
+	struct dentry *test_state;
+
+	test_state = debugfs_create_file(status, 0644, root,
+					 state,
+					 &hv_debugfs_state_fops);
+	if (IS_ERR(test_state)) {
+		pr_debug("debugfs_hyperv: file %s not created\n", status);
+		return PTR_ERR(test_state);
+	}
+
+	return 0;
+}
+
+/* Bind hv device to a dentry for debugfs */
+static void hv_debug_set_dir_dentry(struct hv_device *dev, struct dentry *root)
+{
+	if (hv_debug_root)
+		dev->debug_dir = root;
+}
+
+/* Create all test dentry's and names for fuzz testing */
+int hv_debug_add_dev_dir(struct hv_device *dev)
+{
+	const char *device = dev_name(&dev->device);
+	char *delay_name = "delay";
+	struct dentry *delay, *dev_root;
+	int ret;
+
+	if (!IS_ERR(hv_debug_root)) {
+		dev_root = debugfs_create_dir(device, hv_debug_root);
+		if (IS_ERR(dev_root)) {
+			pr_debug("debugfs_hyperv: hyperv/%s/ not created\n",
+				 device);
+			return PTR_ERR(dev_root);
+		}
+		hv_debug_set_test_state(dev, dev_root);
+		hv_debug_set_dir_dentry(dev, dev_root);
+		delay = debugfs_create_dir(delay_name, dev_root);
+
+		if (IS_ERR(delay)) {
+			pr_debug("debugfs_hyperv: hyperv/%s/%s/ not created\n",
+				 device, delay_name);
+			return PTR_ERR(delay);
+		}
+		ret = hv_debug_delay_files(dev, delay);
+
+		return ret;
+	}
+	pr_debug("debugfs_hyperv: hyperv/ not in root debugfs path\n");
+	return PTR_ERR(hv_debug_root);
+}
+
+/* Remove dentry associated with released hv device */
+void hv_debug_rm_dev_dir(struct hv_device *dev)
+{
+	if (!IS_ERR(hv_debug_root))
+		debugfs_remove_recursive(dev->debug_dir);
+}
+
+/* Remove all dentrys associated with vmbus testing */
+void hv_debug_rm_all_dir(void)
+{
+	debugfs_remove_recursive(hv_debug_root);
+}
+
+/* Delay buffer/message reads on a vmbus channel */
+void hv_debug_delay_test(struct vmbus_channel *channel, enum delay delay_type)
+{
+	struct vmbus_channel *test_channel =    channel->primary_channel ?
+						channel->primary_channel :
+						channel;
+	bool state = test_channel->fuzz_testing_state;
+
+	if (state) {
+		if (delay_type == 0)
+			udelay(test_channel->fuzz_testing_interrupt_delay);
+		else
+			udelay(test_channel->fuzz_testing_message_delay);
+	}
+}
+
+/* Initialize top dentry for vmbus testing */
+int hv_debug_init(void)
+{
+	hv_debug_root = debugfs_create_dir("hyperv", NULL);
+	if (IS_ERR(hv_debug_root)) {
+		pr_debug("debugfs_hyperv: hyperv/ not created\n");
+		return PTR_ERR(hv_debug_root);
+	}
+	return 0;
+}
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
new file mode 100644
index 000000000..336b278b2
--- /dev/null
+++ b/drivers/hv/hv_kvp.c
@@ -0,0 +1,829 @@
+/*
+ * An implementation of key value pair (KVP) functionality for Linux.
+ *
+ *
+ * Copyright (C) 2010, Novell, Inc.
+ * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/net.h>
+#include <linux/nls.h>
+#include <linux/connector.h>
+#include <linux/workqueue.h>
+#include <linux/hyperv.h>
+#include <linux/string.h>
+#include <hyperv/hvhdk.h>
+
+#include "hyperv_vmbus.h"
+#include "hv_utils_transport.h"
+
+/*
+ * Pre win8 version numbers used in ws2008 and ws 2008 r2 (win7)
+ */
+#define WS2008_SRV_MAJOR	1
+#define WS2008_SRV_MINOR	0
+#define WS2008_SRV_VERSION     (WS2008_SRV_MAJOR << 16 | WS2008_SRV_MINOR)
+
+#define WIN7_SRV_MAJOR   3
+#define WIN7_SRV_MINOR   0
+#define WIN7_SRV_VERSION     (WIN7_SRV_MAJOR << 16 | WIN7_SRV_MINOR)
+
+#define WIN8_SRV_MAJOR   4
+#define WIN8_SRV_MINOR   0
+#define WIN8_SRV_VERSION     (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
+
+#define KVP_VER_COUNT 3
+static const int kvp_versions[] = {
+	WIN8_SRV_VERSION,
+	WIN7_SRV_VERSION,
+	WS2008_SRV_VERSION
+};
+
+#define FW_VER_COUNT 2
+static const int fw_versions[] = {
+	UTIL_FW_VERSION,
+	UTIL_WS2K8_FW_VERSION
+};
+
+/*
+ * Global state maintained for transaction that is being processed. For a class
+ * of integration services, including the "KVP service", the specified protocol
+ * is a "request/response" protocol which means that there can only be single
+ * outstanding transaction from the host at any given point in time. We use
+ * this to simplify memory management in this driver - we cache and process
+ * only one message at a time.
+ *
+ * While the request/response protocol is guaranteed by the host, we further
+ * ensure this by serializing packet processing in this driver - we do not
+ * read additional packets from the VMBUS until the current packet is fully
+ * handled.
+ */
+
+static struct {
+	int state;   /* hvutil_device_state */
+	int recv_len; /* number of bytes received. */
+	struct hv_kvp_msg  *kvp_msg; /* current message */
+	struct vmbus_channel *recv_channel; /* chn we got the request */
+	u64 recv_req_id; /* request ID. */
+} kvp_transaction;
+
+/*
+ * This state maintains the version number registered by the daemon.
+ */
+static int dm_reg_value;
+
+static void kvp_send_key(struct work_struct *dummy);
+
+
+static void kvp_respond_to_host(struct hv_kvp_msg *msg, int error);
+static void kvp_timeout_func(struct work_struct *dummy);
+static void kvp_host_handshake_func(struct work_struct *dummy);
+static int kvp_register(int);
+
+static DECLARE_DELAYED_WORK(kvp_timeout_work, kvp_timeout_func);
+static DECLARE_DELAYED_WORK(kvp_host_handshake_work, kvp_host_handshake_func);
+static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);
+
+static const char kvp_devname[] = "vmbus/hv_kvp";
+static u8 *recv_buffer;
+static struct hvutil_transport *hvt;
+/*
+ * Register the kernel component with the user-level daemon.
+ * As part of this registration, pass the LIC version number.
+ * This number has no meaning, it satisfies the registration protocol.
+ */
+#define HV_DRV_VERSION           "3.1"
+
+static void kvp_poll_wrapper(void *channel)
+{
+	/* Transaction is finished, reset the state here to avoid races. */
+	kvp_transaction.state = HVUTIL_READY;
+	tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
+}
+
+static void kvp_register_done(void)
+{
+	/*
+	 * If we're still negotiating with the host cancel the timeout
+	 * work to not poll the channel twice.
+	 */
+	pr_debug("KVP: userspace daemon registered\n");
+	cancel_delayed_work_sync(&kvp_host_handshake_work);
+	hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
+}
+
+static int
+kvp_register(int reg_value)
+{
+	struct hv_kvp_msg *kvp_msg;
+	int ret;
+
+	kvp_msg = kzalloc_obj(*kvp_msg);
+	if (!kvp_msg)
+		return -ENOMEM;
+
+	kvp_msg->kvp_hdr.operation = reg_value;
+	strscpy(kvp_msg->body.kvp_register.version, HV_DRV_VERSION);
+
+	ret = hvutil_transport_send(hvt, kvp_msg, sizeof(*kvp_msg),
+				    kvp_register_done);
+	kfree(kvp_msg);
+	return ret;
+}
+
+static void kvp_timeout_func(struct work_struct *dummy)
+{
+	/*
+	 * If the timer fires, the user-mode component has not responded;
+	 * process the pending transaction.
+	 */
+	kvp_respond_to_host(NULL, HV_E_FAIL);
+
+	hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
+}
+
+static void kvp_host_handshake_func(struct work_struct *dummy)
+{
+	tasklet_schedule(&kvp_transaction.recv_channel->callback_event);
+}
+
+static int kvp_handle_handshake(struct hv_kvp_msg *msg)
+{
+	switch (msg->kvp_hdr.operation) {
+	case KVP_OP_REGISTER:
+		dm_reg_value = KVP_OP_REGISTER;
+		pr_info("KVP: IP injection functionality not available\n");
+		pr_info("KVP: Upgrade the KVP daemon\n");
+		break;
+	case KVP_OP_REGISTER1:
+		dm_reg_value = KVP_OP_REGISTER1;
+		break;
+	default:
+		pr_info("KVP: incompatible daemon\n");
+		pr_info("KVP: KVP version: %d, Daemon version: %d\n",
+			KVP_OP_REGISTER1, msg->kvp_hdr.operation);
+		return -EINVAL;
+	}
+
+	/*
+	 * We have a compatible daemon; complete the handshake.
+	 */
+	pr_debug("KVP: userspace daemon ver. %d connected\n",
+		 msg->kvp_hdr.operation);
+
+	return kvp_register(dm_reg_value);
+}
+
+
+/*
+ * Callback when data is received from user mode.
+ */
+
+static int kvp_on_msg(void *msg, int len)
+{
+	struct hv_kvp_msg *message = (struct hv_kvp_msg *)msg;
+	struct hv_kvp_msg_enumerate *data;
+	int	error = 0;
+
+	if (len < sizeof(*message))
+		return -EINVAL;
+
+	/*
+	 * If we are negotiating the version information
+	 * with the daemon; handle that first.
+	 */
+
+	if (kvp_transaction.state < HVUTIL_READY) {
+		return kvp_handle_handshake(message);
+	}
+
+	/* We didn't send anything to userspace so the reply is spurious */
+	if (kvp_transaction.state < HVUTIL_USERSPACE_REQ)
+		return -EINVAL;
+
+	kvp_transaction.state = HVUTIL_USERSPACE_RECV;
+
+	/*
+	 * Based on the version of the daemon, we propagate errors from the
+	 * daemon differently.
+	 */
+
+	data = &message->body.kvp_enum_data;
+
+	switch (dm_reg_value) {
+	case KVP_OP_REGISTER:
+		/*
+		 * Null string is used to pass back error condition.
+		 */
+		if (data->data.key[0] == 0)
+			error = HV_S_CONT;
+		break;
+
+	case KVP_OP_REGISTER1:
+		/*
+		 * We use the message header information from
+		 * the user level daemon to transmit errors.
+		 */
+		error = message->error;
+		break;
+	}
+
+	/*
+	 * Complete the transaction by forwarding the key value
+	 * to the host. But first, cancel the timeout.
+	 */
+	if (cancel_delayed_work_sync(&kvp_timeout_work)) {
+		kvp_respond_to_host(message, error);
+		hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
+	}
+
+	return 0;
+}
+
+
+static int process_ob_ipinfo(void *in_msg, void *out_msg, int op)
+{
+	struct hv_kvp_msg *in = in_msg;
+	struct hv_kvp_ip_msg *out = out_msg;
+	int len;
+
+	switch (op) {
+	case KVP_OP_GET_IP_INFO:
+		/*
+		 * Transform all parameters into utf16 encoding.
+		 */
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.ip_addr,
+				strlen((char *)in->body.kvp_ip_val.ip_addr),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.ip_addr,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.sub_net,
+				strlen((char *)in->body.kvp_ip_val.sub_net),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.sub_net,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.gate_way,
+				strlen((char *)in->body.kvp_ip_val.gate_way),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.gate_way,
+				MAX_GATEWAY_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.dns_addr,
+				strlen((char *)in->body.kvp_ip_val.dns_addr),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.dns_addr,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.adapter_id,
+				strlen((char *)in->body.kvp_ip_val.adapter_id),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.adapter_id,
+				MAX_ADAPTER_ID_SIZE);
+		if (len < 0)
+			return len;
+
+		out->kvp_ip_val.dhcp_enabled =
+			in->body.kvp_ip_val.dhcp_enabled;
+		out->kvp_ip_val.addr_family =
+			in->body.kvp_ip_val.addr_family;
+	}
+
+	return 0;
+}
+
+static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
+{
+	struct hv_kvp_ip_msg *in = in_msg;
+	struct hv_kvp_msg *out = out_msg;
+
+	switch (op) {
+	case KVP_OP_SET_IP_INFO:
+		/*
+		 * Transform all parameters into utf8 encoding.
+		 */
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.ip_addr,
+				MAX_IP_ADDR_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.ip_addr,
+				MAX_IP_ADDR_SIZE);
+
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.sub_net,
+				MAX_IP_ADDR_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.sub_net,
+				MAX_IP_ADDR_SIZE);
+
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.gate_way,
+				MAX_GATEWAY_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.gate_way,
+				MAX_GATEWAY_SIZE);
+
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.dns_addr,
+				MAX_IP_ADDR_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.dns_addr,
+				MAX_IP_ADDR_SIZE);
+
+		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;
+
+		fallthrough;
+
+	case KVP_OP_GET_IP_INFO:
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
+				MAX_ADAPTER_ID_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.adapter_id,
+				MAX_ADAPTER_ID_SIZE);
+
+		out->body.kvp_ip_val.addr_family = in->kvp_ip_val.addr_family;
+	}
+}
+
+
+
+
+static void
+kvp_send_key(struct work_struct *dummy)
+{
+	struct hv_kvp_msg *message;
+	struct hv_kvp_msg *in_msg;
+	__u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
+	__u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
+	__u32 val32;
+	__u64 val64;
+	int rc;
+
+	/* The transaction state is wrong. */
+	if (kvp_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
+		return;
+
+	message = kzalloc_obj(*message);
+	if (!message)
+		return;
+
+	message->kvp_hdr.operation = operation;
+	message->kvp_hdr.pool = pool;
+	in_msg = kvp_transaction.kvp_msg;
+
+	/*
+	 * The key/value strings sent from the host are encoded
+	 * in utf16; convert it to utf8 strings.
+	 * The host assures us that the utf16 strings will not exceed
+	 * the max lengths specified. We will however, reserve room
+	 * for the string terminating character - in the utf16s_utf8s()
+	 * function we limit the size of the buffer where the converted
+	 * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to guarantee
+	 * that the strings can be properly terminated!
+	 */
+
+	switch (message->kvp_hdr.operation) {
+	case KVP_OP_SET_IP_INFO:
+		process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
+		break;
+	case KVP_OP_GET_IP_INFO:
+		/*
+		 * We only need to pass on the info of operation, adapter_id
+		 * and addr_family to the userland kvp daemon.
+		 */
+		process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
+		break;
+	case KVP_OP_SET:
+		switch (in_msg->body.kvp_set.data.value_type) {
+		case REG_SZ:
+			/*
+			 * The value is a string - utf16 encoding.
+			 */
+			message->body.kvp_set.data.value_size =
+				utf16s_to_utf8s(
+				(wchar_t *)in_msg->body.kvp_set.data.value,
+				in_msg->body.kvp_set.data.value_size,
+				UTF16_LITTLE_ENDIAN,
+				message->body.kvp_set.data.value,
+				HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
+			break;
+
+		case REG_U32:
+			/*
+			 * The value is a 32 bit scalar.
+			 * We save this as a utf8 string.
+			 */
+			val32 = in_msg->body.kvp_set.data.value_u32;
+			message->body.kvp_set.data.value_size =
+				sprintf(message->body.kvp_set.data.value,
+					"%u", val32) + 1;
+			break;
+
+		case REG_U64:
+			/*
+			 * The value is a 64 bit scalar.
+			 * We save this as a utf8 string.
+			 */
+			val64 = in_msg->body.kvp_set.data.value_u64;
+			message->body.kvp_set.data.value_size =
+				sprintf(message->body.kvp_set.data.value,
+					"%llu", val64) + 1;
+			break;
+
+		}
+
+		/*
+		 * The key is always a string - utf16 encoding.
+		 */
+		message->body.kvp_set.data.key_size =
+			utf16s_to_utf8s(
+			(wchar_t *)in_msg->body.kvp_set.data.key,
+			in_msg->body.kvp_set.data.key_size,
+			UTF16_LITTLE_ENDIAN,
+			message->body.kvp_set.data.key,
+			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
+
+		break;
+
+	case KVP_OP_GET:
+		message->body.kvp_get.data.key_size =
+			utf16s_to_utf8s(
+			(wchar_t *)in_msg->body.kvp_get.data.key,
+			in_msg->body.kvp_get.data.key_size,
+			UTF16_LITTLE_ENDIAN,
+			message->body.kvp_get.data.key,
+			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
+		break;
+
+	case KVP_OP_DELETE:
+		message->body.kvp_delete.key_size =
+			utf16s_to_utf8s(
+			(wchar_t *)in_msg->body.kvp_delete.key,
+			in_msg->body.kvp_delete.key_size,
+			UTF16_LITTLE_ENDIAN,
+			message->body.kvp_delete.key,
+			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
+		break;
+
+	case KVP_OP_ENUMERATE:
+		message->body.kvp_enum_data.index =
+			in_msg->body.kvp_enum_data.index;
+		break;
+	}
+
+	kvp_transaction.state = HVUTIL_USERSPACE_REQ;
+	rc = hvutil_transport_send(hvt, message, sizeof(*message), NULL);
+	if (rc) {
+		pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
+		if (cancel_delayed_work_sync(&kvp_timeout_work)) {
+			kvp_respond_to_host(message, HV_E_FAIL);
+			kvp_transaction.state = HVUTIL_READY;
+		}
+	}
+
+	kfree(message);
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+kvp_respond_to_host(struct hv_kvp_msg *msg_to_host, int error)
+{
+	struct hv_kvp_msg  *kvp_msg;
+	struct hv_kvp_exchg_msg_value  *kvp_data;
+	char	*key_name;
+	char	*value;
+	struct icmsg_hdr *icmsghdrp;
+	int	keylen = 0;
+	int	valuelen = 0;
+	u32	buf_len;
+	struct vmbus_channel *channel;
+	u64	req_id;
+	int ret;
+
+	/*
+	 * Copy the global state for completing the transaction. Note that
+	 * only one transaction can be active at a time.
+	 */
+
+	buf_len = kvp_transaction.recv_len;
+	channel = kvp_transaction.recv_channel;
+	req_id = kvp_transaction.recv_req_id;
+
+	icmsghdrp = (struct icmsg_hdr *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (channel->onchannel_callback == NULL)
+		/*
+		 * We have raced with util driver being unloaded;
+		 * silently return.
+		 */
+		return;
+
+	icmsghdrp->status = error;
+
+	/*
+	 * If the error parameter is set, terminate the host's enumeration
+	 * on this pool.
+	 */
+	if (error) {
+		/*
+		 * Something failed or we have timed out;
+		 * terminate the current host-side iteration.
+		 */
+		goto response_done;
+	}
+
+	kvp_msg = (struct hv_kvp_msg *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr) +
+			sizeof(struct icmsg_hdr)];
+
+	switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
+	case KVP_OP_GET_IP_INFO:
+		ret = process_ob_ipinfo(msg_to_host,
+				 (struct hv_kvp_ip_msg *)kvp_msg,
+				 KVP_OP_GET_IP_INFO);
+		if (ret < 0)
+			icmsghdrp->status = HV_E_FAIL;
+
+		goto response_done;
+	case KVP_OP_SET_IP_INFO:
+		goto response_done;
+	case KVP_OP_GET:
+		kvp_data = &kvp_msg->body.kvp_get.data;
+		goto copy_value;
+
+	case KVP_OP_SET:
+	case KVP_OP_DELETE:
+		goto response_done;
+
+	default:
+		break;
+	}
+
+	kvp_data = &kvp_msg->body.kvp_enum_data.data;
+	key_name = msg_to_host->body.kvp_enum_data.data.key;
+
+	/*
+	 * The windows host expects the key/value pair to be encoded
+	 * in utf16. Ensure that the key/value size reported to the host
+	 * will be less than or equal to the MAX size (including the
+	 * terminating character).
+	 */
+	keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
+				(wchar_t *) kvp_data->key,
+				(HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
+	kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */
+
+copy_value:
+	value = msg_to_host->body.kvp_enum_data.data.value;
+	valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
+				(wchar_t *) kvp_data->value,
+				(HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
+	kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */
+
+	/*
+	 * If the utf8s to utf16s conversion failed; notify host
+	 * of the error.
+	 */
+	if ((keylen < 0) || (valuelen < 0))
+		icmsghdrp->status = HV_E_FAIL;
+
+	kvp_data->value_type = REG_SZ; /* all our values are strings */
+
+response_done:
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+
+	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+				VM_PKT_DATA_INBAND, 0);
+}
+
+/*
+ * This callback is invoked when we get a KVP message from the host.
+ * The host ensures that only one KVP transaction can be active at a time.
+ * KVP implementation in Linux needs to forward the key to a user-mde
+ * component to retrieve the corresponding value. Consequently, we cannot
+ * respond to the host in the context of this callback. Since the host
+ * guarantees that at most only one transaction can be active at a time,
+ * we stash away the transaction state in a set of global variables.
+ */
+
+void hv_kvp_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+
+	struct hv_kvp_msg *kvp_msg;
+
+	struct icmsg_hdr *icmsghdrp;
+	int kvp_srv_version;
+	static enum {NEGO_NOT_STARTED,
+		     NEGO_IN_PROGRESS,
+		     NEGO_FINISHED} host_negotiatied = NEGO_NOT_STARTED;
+
+	if (kvp_transaction.state < HVUTIL_READY) {
+		/*
+		 * If userspace daemon is not connected and host is asking
+		 * us to negotiate we need to delay to not lose messages.
+		 * This is important for Failover IP setting.
+		 */
+		if (host_negotiatied == NEGO_NOT_STARTED) {
+			host_negotiatied = NEGO_IN_PROGRESS;
+			schedule_delayed_work(&kvp_host_handshake_work,
+						secs_to_jiffies(HV_UTIL_NEGO_TIMEOUT));
+		}
+		return;
+	}
+	if (kvp_transaction.state > HVUTIL_READY)
+		return;
+
+	if (vmbus_recvpacket(channel, recv_buffer, HV_HYP_PAGE_SIZE * 4, &recvlen, &requestid)) {
+		pr_err_ratelimited("KVP request received. Could not read into recv buf\n");
+		return;
+	}
+
+	if (!recvlen)
+		return;
+
+	/* Ensure recvlen is big enough to read header data */
+	if (recvlen < ICMSG_HDR) {
+		pr_err_ratelimited("KVP request received. Packet length too small: %d\n",
+				   recvlen);
+		return;
+	}
+
+	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+		if (vmbus_prep_negotiate_resp(icmsghdrp,
+				recv_buffer, recvlen,
+				fw_versions, FW_VER_COUNT,
+				kvp_versions, KVP_VER_COUNT,
+				NULL, &kvp_srv_version)) {
+			pr_info("KVP IC version %d.%d\n",
+				kvp_srv_version >> 16,
+				kvp_srv_version & 0xFFFF);
+		}
+	} else if (icmsghdrp->icmsgtype == ICMSGTYPE_KVPEXCHANGE) {
+		/*
+		 * recvlen is not checked against sizeof(struct kvp_msg) because kvp_msg contains
+		 * a union of structs and the msg type received is not known. Code using this
+		 * struct should provide validation when accessing its fields.
+		 */
+		kvp_msg = (struct hv_kvp_msg *)&recv_buffer[ICMSG_HDR];
+
+		/*
+		 * Stash away this global state for completing the
+		 * transaction; note transactions are serialized.
+		 */
+
+		kvp_transaction.recv_len = recvlen;
+		kvp_transaction.recv_req_id = requestid;
+		kvp_transaction.kvp_msg = kvp_msg;
+
+		if (kvp_transaction.state < HVUTIL_READY) {
+			/* Userspace is not registered yet */
+			kvp_respond_to_host(NULL, HV_E_FAIL);
+			return;
+		}
+		kvp_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
+
+		/*
+		 * Get the information from the
+		 * user-mode component.
+		 * component. This transaction will be
+		 * completed when we get the value from
+		 * the user-mode component.
+		 * Set a timeout to deal with
+		 * user-mode not responding.
+		 */
+		schedule_work(&kvp_sendkey_work);
+		schedule_delayed_work(&kvp_timeout_work,
+				      secs_to_jiffies(HV_UTIL_TIMEOUT));
+
+		return;
+
+	} else {
+		pr_err_ratelimited("KVP request received. Invalid msg type: %d\n",
+				   icmsghdrp->icmsgtype);
+		return;
+	}
+
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+		| ICMSGHDRFLAG_RESPONSE;
+
+	vmbus_sendpacket(channel, recv_buffer,
+			 recvlen, requestid,
+			 VM_PKT_DATA_INBAND, 0);
+
+	host_negotiatied = NEGO_FINISHED;
+	hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
+}
+
+static void kvp_on_reset(void)
+{
+	if (cancel_delayed_work_sync(&kvp_timeout_work))
+		kvp_respond_to_host(NULL, HV_E_FAIL);
+	kvp_transaction.state = HVUTIL_DEVICE_INIT;
+}
+
+int
+hv_kvp_init(struct hv_util_service *srv)
+{
+	recv_buffer = srv->recv_buffer;
+	kvp_transaction.recv_channel = srv->channel;
+	kvp_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 4;
+
+	/*
+	 * When this driver loads, the user level daemon that
+	 * processes the host requests may not yet be running.
+	 * Defer processing channel callbacks until the daemon
+	 * has registered.
+	 */
+	kvp_transaction.state = HVUTIL_DEVICE_INIT;
+
+	return 0;
+}
+
+int
+hv_kvp_init_transport(void)
+{
+	hvt = hvutil_transport_init(kvp_devname, CN_KVP_IDX, CN_KVP_VAL,
+				    kvp_on_msg, kvp_on_reset);
+	if (!hvt)
+		return -EFAULT;
+
+	return 0;
+}
+
+static void hv_kvp_cancel_work(void)
+{
+	cancel_delayed_work_sync(&kvp_host_handshake_work);
+	cancel_delayed_work_sync(&kvp_timeout_work);
+	cancel_work_sync(&kvp_sendkey_work);
+}
+
+int hv_kvp_pre_suspend(void)
+{
+	struct vmbus_channel *channel = kvp_transaction.recv_channel;
+
+	tasklet_disable(&channel->callback_event);
+
+	/*
+	 * If there is a pending transtion, it's unnecessary to tell the host
+	 * that the transaction will fail, because that is implied when
+	 * util_suspend() calls vmbus_close() later.
+	 */
+	hv_kvp_cancel_work();
+
+	/*
+	 * Forece the state to READY to handle the ICMSGTYPE_NEGOTIATE message
+	 * later. The user space daemon may go out of order and its write()
+	 * may fail with EINVAL: this doesn't matter since the daemon will
+	 * reset the device by closing and re-opening it.
+	 */
+	kvp_transaction.state = HVUTIL_READY;
+	return 0;
+}
+
+int hv_kvp_pre_resume(void)
+{
+	struct vmbus_channel *channel = kvp_transaction.recv_channel;
+
+	tasklet_enable(&channel->callback_event);
+
+	return 0;
+}
+
+void hv_kvp_deinit(void)
+{
+	kvp_transaction.state = HVUTIL_DEVICE_DYING;
+
+	hv_kvp_cancel_work();
+
+	hvutil_transport_destroy(hvt);
+}
diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
new file mode 100644
index 000000000..57b2c6419
--- /dev/null
+++ b/drivers/hv/hv_proc.c
@@ -0,0 +1,288 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clockchips.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>
+#include <linux/minmax.h>
+#include <linux/export.h>
+#include <asm/mshyperv.h>
+
+/*
+ * See struct hv_deposit_memory. The first u64 is partition ID, the rest
+ * are GPAs.
+ */
+#define HV_DEPOSIT_MAX (HV_HYP_PAGE_SIZE / sizeof(u64) - 1)
+
+/* Deposits exact number of pages. Must be called with interrupts enabled.  */
+int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
+{
+	struct page **pages, *page;
+	int *counts;
+	int num_allocations;
+	int i, j, page_count;
+	int order;
+	u64 status;
+	int ret;
+	u64 base_pfn;
+	struct hv_deposit_memory *input_page;
+	unsigned long flags;
+
+	if (num_pages > HV_DEPOSIT_MAX)
+		return -E2BIG;
+	if (!num_pages)
+		return 0;
+
+	/* One buffer for page pointers and counts */
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+	pages = page_address(page);
+
+	counts = kzalloc_objs(int, HV_DEPOSIT_MAX);
+	if (!counts) {
+		free_page((unsigned long)pages);
+		return -ENOMEM;
+	}
+
+	/* Allocate all the pages before disabling interrupts */
+	i = 0;
+
+	while (num_pages) {
+		/* Find highest order we can actually allocate */
+		order = 31 - __builtin_clz(num_pages);
+
+		while (1) {
+			pages[i] = alloc_pages_node(node, GFP_KERNEL, order);
+			if (pages[i])
+				break;
+			if (!order) {
+				ret = -ENOMEM;
+				num_allocations = i;
+				goto err_free_allocations;
+			}
+			--order;
+		}
+
+		split_page(pages[i], order);
+		counts[i] = 1 << order;
+		num_pages -= counts[i];
+		i++;
+	}
+	num_allocations = i;
+
+	local_irq_save(flags);
+
+	input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	input_page->partition_id = partition_id;
+
+	/* Populate gpa_page_list - these will fit on the input page */
+	for (i = 0, page_count = 0; i < num_allocations; ++i) {
+		base_pfn = page_to_pfn(pages[i]);
+		for (j = 0; j < counts[i]; ++j, ++page_count)
+			input_page->gpa_page_list[page_count] = base_pfn + j;
+	}
+	status = hv_do_rep_hypercall(HVCALL_DEPOSIT_MEMORY,
+				     page_count, 0, input_page, NULL);
+	local_irq_restore(flags);
+	if (!hv_result_success(status)) {
+		hv_status_err(status, "\n");
+		ret = hv_result_to_errno(status);
+		goto err_free_allocations;
+	}
+
+	ret = 0;
+	goto free_buf;
+
+err_free_allocations:
+	for (i = 0; i < num_allocations; ++i) {
+		base_pfn = page_to_pfn(pages[i]);
+		for (j = 0; j < counts[i]; ++j)
+			__free_page(pfn_to_page(base_pfn + j));
+	}
+
+free_buf:
+	free_page((unsigned long)pages);
+	kfree(counts);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hv_call_deposit_pages);
+
+int hv_deposit_memory_node(int node, u64 partition_id,
+			   u64 hv_status)
+{
+	u32 num_pages = 1;
+
+	switch (hv_result(hv_status)) {
+	case HV_STATUS_INSUFFICIENT_MEMORY:
+		break;
+	case HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY:
+		num_pages = HV_MAX_CONTIGUOUS_ALLOCATION_PAGES;
+		break;
+
+	case HV_STATUS_INSUFFICIENT_CONTIGUOUS_ROOT_MEMORY:
+		num_pages = HV_MAX_CONTIGUOUS_ALLOCATION_PAGES;
+		fallthrough;
+	case HV_STATUS_INSUFFICIENT_ROOT_MEMORY:
+		if (!hv_root_partition()) {
+			hv_status_err(hv_status, "Unexpected root memory deposit\n");
+			return -ENOMEM;
+		}
+		partition_id = HV_PARTITION_ID_SELF;
+		break;
+
+	default:
+		hv_status_err(hv_status, "Unexpected!\n");
+		return -ENOMEM;
+	}
+	return hv_call_deposit_pages(node, partition_id, num_pages);
+}
+EXPORT_SYMBOL_GPL(hv_deposit_memory_node);
+
+bool hv_result_needs_memory(u64 status)
+{
+	switch (hv_result(status)) {
+	case HV_STATUS_INSUFFICIENT_MEMORY:
+	case HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY:
+	case HV_STATUS_INSUFFICIENT_ROOT_MEMORY:
+	case HV_STATUS_INSUFFICIENT_CONTIGUOUS_ROOT_MEMORY:
+		return true;
+	}
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_result_needs_memory);
+
+int hv_call_add_logical_proc(int node, u32 lp_index, u32 apic_id)
+{
+	struct hv_input_add_logical_processor *input;
+	struct hv_output_add_logical_processor *output;
+	u64 status;
+	unsigned long flags;
+	int ret = 0;
+
+	/*
+	 * When adding a logical processor, the hypervisor may return
+	 * HV_STATUS_INSUFFICIENT_MEMORY. When that happens, we deposit more
+	 * pages and retry.
+	 */
+	do {
+		local_irq_save(flags);
+
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		/* We don't do anything with the output right now */
+		output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+		input->lp_index = lp_index;
+		input->apic_id = apic_id;
+		input->proximity_domain_info = hv_numa_node_to_pxm_info(node);
+		status = hv_do_hypercall(HVCALL_ADD_LOGICAL_PROCESSOR,
+					 input, output);
+		local_irq_restore(flags);
+
+		if (!hv_result_needs_memory(status)) {
+			if (!hv_result_success(status)) {
+				hv_status_err(status, "cpu %u apic ID: %u\n",
+					      lp_index, apic_id);
+				ret = hv_result_to_errno(status);
+			}
+			break;
+		}
+		ret = hv_deposit_memory_node(node, hv_current_partition_id,
+					     status);
+	} while (!ret);
+
+	return ret;
+}
+
+int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags)
+{
+	struct hv_create_vp *input;
+	u64 status;
+	unsigned long irq_flags;
+	int ret = 0;
+
+	/* Root VPs don't seem to need pages deposited */
+	if (partition_id != hv_current_partition_id) {
+		/* The value 90 is empirically determined. It may change. */
+		ret = hv_call_deposit_pages(node, partition_id, 90);
+		if (ret)
+			return ret;
+	}
+
+	do {
+		local_irq_save(irq_flags);
+
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		input->partition_id = partition_id;
+		input->vp_index = vp_index;
+		input->flags = flags;
+		input->subnode_type = HV_SUBNODE_ANY;
+		input->proximity_domain_info = hv_numa_node_to_pxm_info(node);
+		status = hv_do_hypercall(HVCALL_CREATE_VP, input, NULL);
+		local_irq_restore(irq_flags);
+
+		if (!hv_result_needs_memory(status)) {
+			if (!hv_result_success(status)) {
+				hv_status_err(status, "vcpu: %u, lp: %u\n",
+					      vp_index, flags);
+				ret = hv_result_to_errno(status);
+			}
+			break;
+		}
+		ret = hv_deposit_memory_node(node, partition_id, status);
+
+	} while (!ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hv_call_create_vp);
+
+int hv_call_notify_all_processors_started(void)
+{
+	struct hv_input_notify_partition_event *input;
+	u64 status;
+	unsigned long irq_flags;
+	int ret = 0;
+
+	local_irq_save(irq_flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(input, 0, sizeof(*input));
+	input->event = HV_PARTITION_ALL_LOGICAL_PROCESSORS_STARTED;
+	status = hv_do_hypercall(HVCALL_NOTIFY_PARTITION_EVENT,
+				 input, NULL);
+	local_irq_restore(irq_flags);
+
+	if (!hv_result_success(status)) {
+		hv_status_err(status, "\n");
+		ret = hv_result_to_errno(status);
+	}
+	return ret;
+}
+
+bool hv_lp_exists(u32 lp_index)
+{
+	struct hv_input_get_logical_processor_run_time *input;
+	struct hv_output_get_logical_processor_run_time *output;
+	unsigned long flags;
+	u64 status;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	input->lp_index = lp_index;
+	status = hv_do_hypercall(HVCALL_GET_LOGICAL_PROCESSOR_RUN_TIME,
+				 input, output);
+	local_irq_restore(flags);
+
+	if (!hv_result_success(status) &&
+	    hv_result(status) != HV_STATUS_INVALID_LP_INDEX) {
+		hv_status_err(status, "\n");
+		BUG();
+	}
+
+	return hv_result_success(status);
+}
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
new file mode 100644
index 000000000..847dc69e8
--- /dev/null
+++ b/drivers/hv/hv_snapshot.c
@@ -0,0 +1,460 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * An implementation of host initiated guest snapshot.
+ *
+ * Copyright (C) 2013, Microsoft, Inc.
+ * Author : K. Y. Srinivasan <kys@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/net.h>
+#include <linux/nls.h>
+#include <linux/connector.h>
+#include <linux/workqueue.h>
+#include <linux/hyperv.h>
+#include <hyperv/hvhdk.h>
+
+#include "hyperv_vmbus.h"
+#include "hv_utils_transport.h"
+
+#define VSS_MAJOR  5
+#define VSS_MINOR  0
+#define VSS_VERSION    (VSS_MAJOR << 16 | VSS_MINOR)
+
+#define VSS_VER_COUNT 1
+static const int vss_versions[] = {
+	VSS_VERSION
+};
+
+#define FW_VER_COUNT 1
+static const int fw_versions[] = {
+	UTIL_FW_VERSION
+};
+
+/* See comment with struct hv_vss_msg regarding the max VMbus packet size */
+#define VSS_MAX_PKT_SIZE (HV_HYP_PAGE_SIZE * 2)
+
+/*
+ * Timeout values are based on expecations from host
+ */
+#define VSS_FREEZE_TIMEOUT (15 * 60)
+
+/*
+ * Global state maintained for transaction that is being processed. For a class
+ * of integration services, including the "VSS service", the specified protocol
+ * is a "request/response" protocol which means that there can only be single
+ * outstanding transaction from the host at any given point in time. We use
+ * this to simplify memory management in this driver - we cache and process
+ * only one message at a time.
+ *
+ * While the request/response protocol is guaranteed by the host, we further
+ * ensure this by serializing packet processing in this driver - we do not
+ * read additional packets from the VMBUs until the current packet is fully
+ * handled.
+ */
+
+static struct {
+	int state;   /* hvutil_device_state */
+	int recv_len; /* number of bytes received. */
+	struct vmbus_channel *recv_channel; /* chn we got the request */
+	u64 recv_req_id; /* request ID. */
+	struct hv_vss_msg  *msg; /* current message */
+} vss_transaction;
+
+
+static void vss_respond_to_host(int error);
+
+/*
+ * This state maintains the version number registered by the daemon.
+ */
+static int dm_reg_value;
+
+static const char vss_devname[] = "vmbus/hv_vss";
+static __u8 *recv_buffer;
+static struct hvutil_transport *hvt;
+
+static void vss_timeout_func(struct work_struct *dummy);
+static void vss_handle_request(struct work_struct *dummy);
+
+static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
+static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
+
+static void vss_poll_wrapper(void *channel)
+{
+	/* Transaction is finished, reset the state here to avoid races. */
+	vss_transaction.state = HVUTIL_READY;
+	tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
+}
+
+/*
+ * Callback when data is received from user mode.
+ */
+
+static void vss_timeout_func(struct work_struct *dummy)
+{
+	/*
+	 * Timeout waiting for userspace component to reply happened.
+	 */
+	pr_warn("VSS: timeout waiting for daemon to reply\n");
+	vss_respond_to_host(HV_E_FAIL);
+
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
+}
+
+static void vss_register_done(void)
+{
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
+	pr_debug("VSS: userspace daemon registered\n");
+}
+
+static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
+{
+	u32 our_ver = VSS_OP_REGISTER1;
+
+	switch (vss_msg->vss_hdr.operation) {
+	case VSS_OP_REGISTER:
+		/* Daemon doesn't expect us to reply */
+		dm_reg_value = VSS_OP_REGISTER;
+		break;
+	case VSS_OP_REGISTER1:
+		/* Daemon expects us to reply with our own version */
+		if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
+					  vss_register_done))
+			return -EFAULT;
+		dm_reg_value = VSS_OP_REGISTER1;
+		break;
+	default:
+		return -EINVAL;
+	}
+	pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
+	return 0;
+}
+
+static int vss_on_msg(void *msg, int len)
+{
+	struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
+
+	if (len != sizeof(*vss_msg)) {
+		pr_debug("VSS: Message size does not match length\n");
+		return -EINVAL;
+	}
+
+	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
+	    vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
+		/*
+		 * Don't process registration messages if we're in the middle
+		 * of a transaction processing.
+		 */
+		if (vss_transaction.state > HVUTIL_READY) {
+			pr_debug("VSS: Got unexpected registration request\n");
+			return -EINVAL;
+		}
+
+		return vss_handle_handshake(vss_msg);
+	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
+		vss_transaction.state = HVUTIL_USERSPACE_RECV;
+
+		if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
+			vss_transaction.msg->vss_cf.flags =
+				VSS_HBU_NO_AUTO_RECOVERY;
+
+		if (cancel_delayed_work_sync(&vss_timeout_work)) {
+			vss_respond_to_host(vss_msg->error);
+			/* Transaction is finished, reset the state. */
+			hv_poll_channel(vss_transaction.recv_channel,
+					vss_poll_wrapper);
+		}
+	} else {
+		/* This is a spurious call! */
+		pr_debug("VSS: Transaction not active\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void vss_send_op(void)
+{
+	int op = vss_transaction.msg->vss_hdr.operation;
+	int rc;
+	struct hv_vss_msg *vss_msg;
+
+	/* The transaction state is wrong. */
+	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
+		pr_debug("VSS: Unexpected attempt to send to daemon\n");
+		return;
+	}
+
+	vss_msg = kzalloc_obj(*vss_msg);
+	if (!vss_msg)
+		return;
+
+	vss_msg->vss_hdr.operation = op;
+
+	vss_transaction.state = HVUTIL_USERSPACE_REQ;
+
+	schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
+				secs_to_jiffies(VSS_FREEZE_TIMEOUT) :
+				secs_to_jiffies(HV_UTIL_TIMEOUT));
+
+	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
+	if (rc) {
+		pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
+		if (cancel_delayed_work_sync(&vss_timeout_work)) {
+			vss_respond_to_host(HV_E_FAIL);
+			vss_transaction.state = HVUTIL_READY;
+		}
+	}
+
+	kfree(vss_msg);
+}
+
+static void vss_handle_request(struct work_struct *dummy)
+{
+	switch (vss_transaction.msg->vss_hdr.operation) {
+	/*
+	 * Initiate a "freeze/thaw" operation in the guest.
+	 * We respond to the host once the operation is complete.
+	 *
+	 * We send the message to the user space daemon and the operation is
+	 * performed in the daemon.
+	 */
+	case VSS_OP_THAW:
+	case VSS_OP_FREEZE:
+	case VSS_OP_HOT_BACKUP:
+		if (vss_transaction.state < HVUTIL_READY) {
+			/* Userspace is not registered yet */
+			pr_debug("VSS: Not ready for request.\n");
+			vss_respond_to_host(HV_E_FAIL);
+			return;
+		}
+
+		pr_debug("VSS: Received request for op code: %d\n",
+			vss_transaction.msg->vss_hdr.operation);
+		vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
+		vss_send_op();
+		return;
+	case VSS_OP_GET_DM_INFO:
+		vss_transaction.msg->dm_info.flags = 0;
+		break;
+	default:
+		break;
+	}
+
+	vss_respond_to_host(0);
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+vss_respond_to_host(int error)
+{
+	struct icmsg_hdr *icmsghdrp;
+	u32	buf_len;
+	struct vmbus_channel *channel;
+	u64	req_id;
+
+	/*
+	 * Copy the global state for completing the transaction. Note that
+	 * only one transaction can be active at a time.
+	 */
+
+	buf_len = vss_transaction.recv_len;
+	channel = vss_transaction.recv_channel;
+	req_id = vss_transaction.recv_req_id;
+
+	icmsghdrp = (struct icmsg_hdr *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (channel->onchannel_callback == NULL)
+		/*
+		 * We have raced with util driver being unloaded;
+		 * silently return.
+		 */
+		return;
+
+	icmsghdrp->status = error;
+
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+
+	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+				VM_PKT_DATA_INBAND, 0);
+
+}
+
+/*
+ * This callback is invoked when we get a VSS message from the host.
+ * The host ensures that only one VSS transaction can be active at a time.
+ */
+
+void hv_vss_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct hv_vss_msg *vss_msg;
+	int vss_srv_version;
+
+	struct icmsg_hdr *icmsghdrp;
+
+	if (vss_transaction.state > HVUTIL_READY)
+		return;
+
+	if (vmbus_recvpacket(channel, recv_buffer, VSS_MAX_PKT_SIZE, &recvlen, &requestid)) {
+		pr_err_ratelimited("VSS request received. Could not read into recv buf\n");
+		return;
+	}
+
+	if (!recvlen)
+		return;
+
+	/* Ensure recvlen is big enough to read header data */
+	if (recvlen < ICMSG_HDR) {
+		pr_err_ratelimited("VSS request received. Packet length too small: %d\n",
+				   recvlen);
+		return;
+	}
+
+	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+		if (vmbus_prep_negotiate_resp(icmsghdrp,
+				recv_buffer, recvlen,
+				fw_versions, FW_VER_COUNT,
+				vss_versions, VSS_VER_COUNT,
+				NULL, &vss_srv_version)) {
+
+			pr_info("VSS IC version %d.%d\n",
+				vss_srv_version >> 16,
+				vss_srv_version & 0xFFFF);
+		}
+	} else if (icmsghdrp->icmsgtype == ICMSGTYPE_VSS) {
+		/* Ensure recvlen is big enough to contain hv_vss_msg */
+		if (recvlen < ICMSG_HDR + sizeof(struct hv_vss_msg)) {
+			pr_err_ratelimited("Invalid VSS msg. Packet length too small: %u\n",
+					   recvlen);
+			return;
+		}
+		vss_msg = (struct hv_vss_msg *)&recv_buffer[ICMSG_HDR];
+
+		/*
+		 * Stash away this global state for completing the
+		 * transaction; note transactions are serialized.
+		 */
+
+		vss_transaction.recv_len = recvlen;
+		vss_transaction.recv_req_id = requestid;
+		vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
+
+		schedule_work(&vss_handle_request_work);
+		return;
+	} else {
+		pr_err_ratelimited("VSS request received. Invalid msg type: %d\n",
+				   icmsghdrp->icmsgtype);
+		return;
+	}
+
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION |
+		ICMSGHDRFLAG_RESPONSE;
+	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
+			 VM_PKT_DATA_INBAND, 0);
+}
+
+static void vss_on_reset(void)
+{
+	if (cancel_delayed_work_sync(&vss_timeout_work))
+		vss_respond_to_host(HV_E_FAIL);
+	vss_transaction.state = HVUTIL_DEVICE_INIT;
+}
+
+int
+hv_vss_init(struct hv_util_service *srv)
+{
+	recv_buffer = srv->recv_buffer;
+	vss_transaction.recv_channel = srv->channel;
+	vss_transaction.recv_channel->max_pkt_size = VSS_MAX_PKT_SIZE;
+
+	/*
+	 * When this driver loads, the user level daemon that
+	 * processes the host requests may not yet be running.
+	 * Defer processing channel callbacks until the daemon
+	 * has registered.
+	 */
+	vss_transaction.state = HVUTIL_DEVICE_INIT;
+
+	return 0;
+}
+
+int
+hv_vss_init_transport(void)
+{
+	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
+				    vss_on_msg, vss_on_reset);
+	if (!hvt) {
+		pr_warn("VSS: Failed to initialize transport\n");
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static void hv_vss_cancel_work(void)
+{
+	cancel_delayed_work_sync(&vss_timeout_work);
+	cancel_work_sync(&vss_handle_request_work);
+}
+
+int hv_vss_pre_suspend(void)
+{
+	struct vmbus_channel *channel = vss_transaction.recv_channel;
+	struct hv_vss_msg *vss_msg;
+
+	/*
+	 * Fake a THAW message for the user space daemon in case the daemon
+	 * has frozen the file systems. It doesn't matter if there is already
+	 * a message pending to be delivered to the user space since we force
+	 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's
+	 * write() will fail with EINVAL (see vss_on_msg()), and the daemon
+	 * will reset the device by closing and re-opening it.
+	 */
+	vss_msg = kzalloc_obj(*vss_msg);
+	if (!vss_msg)
+		return -ENOMEM;
+
+	tasklet_disable(&channel->callback_event);
+
+	vss_msg->vss_hdr.operation = VSS_OP_THAW;
+
+	/* Cancel any possible pending work. */
+	hv_vss_cancel_work();
+
+	/* We don't care about the return value. */
+	hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
+
+	kfree(vss_msg);
+
+	vss_transaction.state = HVUTIL_READY;
+
+	/* tasklet_enable() will be called in hv_vss_pre_resume(). */
+	return 0;
+}
+
+int hv_vss_pre_resume(void)
+{
+	struct vmbus_channel *channel = vss_transaction.recv_channel;
+
+	tasklet_enable(&channel->callback_event);
+
+	return 0;
+}
+
+void hv_vss_deinit(void)
+{
+	vss_transaction.state = HVUTIL_DEVICE_DYING;
+
+	hv_vss_cancel_work();
+
+	hvutil_transport_destroy(hvt);
+}
diff --git a/drivers/hv/hv_trace.c b/drivers/hv/hv_trace.c
new file mode 100644
index 000000000..38d359cf1
--- /dev/null
+++ b/drivers/hv/hv_trace.c
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "hyperv_vmbus.h"
+
+#define CREATE_TRACE_POINTS
+#include "hv_trace.h"
diff --git a/drivers/hv/hv_trace.h b/drivers/hv/hv_trace.h
new file mode 100644
index 000000000..c02a1719e
--- /dev/null
+++ b/drivers/hv/hv_trace.h
@@ -0,0 +1,361 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM hyperv
+
+#if !defined(_HV_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _HV_TRACE_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(vmbus_hdr_msg,
+	TP_PROTO(const struct vmbus_channel_message_header *hdr),
+	TP_ARGS(hdr),
+	TP_STRUCT__entry(__field(unsigned int, msgtype)),
+	TP_fast_assign(__entry->msgtype = hdr->msgtype;),
+	TP_printk("msgtype=%u", __entry->msgtype)
+);
+
+DEFINE_EVENT(vmbus_hdr_msg, vmbus_on_msg_dpc,
+	TP_PROTO(const struct vmbus_channel_message_header *hdr),
+	TP_ARGS(hdr)
+);
+
+DEFINE_EVENT(vmbus_hdr_msg, vmbus_on_message,
+	TP_PROTO(const struct vmbus_channel_message_header *hdr),
+	TP_ARGS(hdr)
+);
+
+TRACE_EVENT(vmbus_onoffer,
+	    TP_PROTO(const struct vmbus_channel_offer_channel *offer),
+	    TP_ARGS(offer),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u8, monitorid)
+		    __field(u16, is_ddc_int)
+		    __field(u32, connection_id)
+		    __array(char, if_type, 16)
+		    __array(char, if_instance, 16)
+		    __field(u16, chn_flags)
+		    __field(u16, mmio_mb)
+		    __field(u16, sub_idx)
+		    ),
+	    TP_fast_assign(__entry->child_relid = offer->child_relid;
+			   __entry->monitorid = offer->monitorid;
+			   __entry->is_ddc_int = offer->is_dedicated_interrupt;
+			   __entry->connection_id = offer->connection_id;
+			   export_guid(__entry->if_type, &offer->offer.if_type);
+			   export_guid(__entry->if_instance, &offer->offer.if_instance);
+			   __entry->chn_flags = offer->offer.chn_flags;
+			   __entry->mmio_mb = offer->offer.mmio_megabytes;
+			   __entry->sub_idx = offer->offer.sub_channel_index;
+		    ),
+	    TP_printk("child_relid 0x%x, monitorid 0x%x, is_dedicated %d, "
+		      "connection_id 0x%x, if_type %pUl, if_instance %pUl, "
+		      "chn_flags 0x%x, mmio_megabytes %d, sub_channel_index %d",
+		      __entry->child_relid, __entry->monitorid,
+		      __entry->is_ddc_int, __entry->connection_id,
+		      __entry->if_type, __entry->if_instance,
+		      __entry->chn_flags, __entry->mmio_mb,
+		      __entry->sub_idx
+		    )
+	);
+
+TRACE_EVENT(vmbus_onoffer_rescind,
+	    TP_PROTO(const struct vmbus_channel_rescind_offer *offer),
+	    TP_ARGS(offer),
+	    TP_STRUCT__entry(__field(u32, child_relid)),
+	    TP_fast_assign(__entry->child_relid = offer->child_relid),
+	    TP_printk("child_relid 0x%x", __entry->child_relid)
+	);
+
+TRACE_EVENT(vmbus_onopen_result,
+	    TP_PROTO(const struct vmbus_channel_open_result *result),
+	    TP_ARGS(result),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, openid)
+		    __field(u32, status)
+		    ),
+	    TP_fast_assign(__entry->child_relid = result->child_relid;
+			   __entry->openid = result->openid;
+			   __entry->status = result->status;
+		    ),
+	    TP_printk("child_relid 0x%x, openid %d, status %d",
+		      __entry->child_relid,  __entry->openid,  __entry->status
+		    )
+	);
+
+TRACE_EVENT(vmbus_ongpadl_created,
+	    TP_PROTO(const struct vmbus_channel_gpadl_created *gpadlcreated),
+	    TP_ARGS(gpadlcreated),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, gpadl)
+		    __field(u32, status)
+		    ),
+	    TP_fast_assign(__entry->child_relid = gpadlcreated->child_relid;
+			   __entry->gpadl = gpadlcreated->gpadl;
+			   __entry->status = gpadlcreated->creation_status;
+		    ),
+	    TP_printk("child_relid 0x%x, gpadl 0x%x, creation_status %d",
+		      __entry->child_relid,  __entry->gpadl,  __entry->status
+		    )
+	);
+
+TRACE_EVENT(vmbus_onmodifychannel_response,
+	    TP_PROTO(const struct vmbus_channel_modifychannel_response *response),
+	    TP_ARGS(response),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, status)
+		    ),
+	    TP_fast_assign(__entry->child_relid = response->child_relid;
+			   __entry->status = response->status;
+		    ),
+	    TP_printk("child_relid 0x%x, status %d",
+		      __entry->child_relid,  __entry->status
+		    )
+	);
+
+TRACE_EVENT(vmbus_ongpadl_torndown,
+	    TP_PROTO(const struct vmbus_channel_gpadl_torndown *gpadltorndown),
+	    TP_ARGS(gpadltorndown),
+	    TP_STRUCT__entry(__field(u32, gpadl)),
+	    TP_fast_assign(__entry->gpadl = gpadltorndown->gpadl),
+	    TP_printk("gpadl 0x%x", __entry->gpadl)
+	);
+
+TRACE_EVENT(vmbus_onversion_response,
+	    TP_PROTO(const struct vmbus_channel_version_response *response),
+	    TP_ARGS(response),
+	    TP_STRUCT__entry(
+		    __field(u8, ver)
+		    ),
+	    TP_fast_assign(__entry->ver = response->version_supported;
+		    ),
+	    TP_printk("version_supported %d", __entry->ver)
+	);
+
+TRACE_EVENT(vmbus_request_offers,
+	    TP_PROTO(int ret),
+	    TP_ARGS(ret),
+	    TP_STRUCT__entry(__field(int, ret)),
+	    TP_fast_assign(__entry->ret = ret),
+	    TP_printk("sending ret %d", __entry->ret)
+	);
+
+TRACE_EVENT(vmbus_open,
+	    TP_PROTO(const struct vmbus_channel_open_channel *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, openid)
+		    __field(u32, gpadlhandle)
+		    __field(u32, target_vp)
+		    __field(u32, offset)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->child_relid = msg->child_relid;
+		    __entry->openid = msg->openid;
+		    __entry->gpadlhandle = msg->ringbuffer_gpadlhandle;
+		    __entry->target_vp = msg->target_vp;
+		    __entry->offset = msg->downstream_ringbuffer_pageoffset;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending child_relid 0x%x, openid %d, "
+		      "gpadlhandle 0x%x, target_vp 0x%x, offset 0x%x, ret %d",
+		      __entry->child_relid,  __entry->openid,
+		      __entry->gpadlhandle, __entry->target_vp,
+		      __entry->offset, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_close_internal,
+	    TP_PROTO(const struct vmbus_channel_close_channel *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->child_relid = msg->child_relid;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending child_relid 0x%x, ret %d", __entry->child_relid,
+		    __entry->ret)
+	);
+
+TRACE_EVENT(vmbus_establish_gpadl_header,
+	    TP_PROTO(const struct vmbus_channel_gpadl_header *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, gpadl)
+		    __field(u16, range_buflen)
+		    __field(u16, rangecount)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->child_relid = msg->child_relid;
+		    __entry->gpadl = msg->gpadl;
+		    __entry->range_buflen = msg->range_buflen;
+		    __entry->rangecount = msg->rangecount;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending child_relid 0x%x, gpadl 0x%x, range_buflen %d "
+		      "rangecount %d, ret %d",
+		      __entry->child_relid, __entry->gpadl,
+		      __entry->range_buflen, __entry->rangecount, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_establish_gpadl_body,
+	    TP_PROTO(const struct vmbus_channel_gpadl_body *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, msgnumber)
+		    __field(u32, gpadl)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->msgnumber = msg->msgnumber;
+		    __entry->gpadl = msg->gpadl;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending msgnumber %d, gpadl 0x%x, ret %d",
+		      __entry->msgnumber, __entry->gpadl, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_teardown_gpadl,
+	    TP_PROTO(const struct vmbus_channel_gpadl_teardown *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, gpadl)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->child_relid = msg->child_relid;
+		    __entry->gpadl = msg->gpadl;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending child_relid 0x%x, gpadl 0x%x, ret %d",
+		      __entry->child_relid, __entry->gpadl, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_negotiate_version,
+	    TP_PROTO(const struct vmbus_channel_initiate_contact *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, ver)
+		    __field(u32, target_vcpu)
+		    __field(int, ret)
+		    __field(u64, int_page)
+		    __field(u64, mon_page1)
+		    __field(u64, mon_page2)
+		    ),
+	    TP_fast_assign(
+		    __entry->ver = msg->vmbus_version_requested;
+		    __entry->target_vcpu = msg->target_vcpu;
+		    __entry->int_page = msg->interrupt_page;
+		    __entry->mon_page1 = msg->monitor_page1;
+		    __entry->mon_page2 = msg->monitor_page2;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending vmbus_version_requested %d, target_vcpu 0x%x, "
+		      "pages %llx:%llx:%llx, ret %d",
+		      __entry->ver, __entry->target_vcpu, __entry->int_page,
+		      __entry->mon_page1, __entry->mon_page2, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_release_relid,
+	    TP_PROTO(const struct vmbus_channel_relid_released *msg, int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->child_relid = msg->child_relid;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending child_relid 0x%x, ret %d",
+		      __entry->child_relid, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_send_tl_connect_request,
+	    TP_PROTO(const struct vmbus_channel_tl_connect_request *msg,
+		     int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __array(char, guest_id, 16)
+		    __array(char, host_id, 16)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    export_guid(__entry->guest_id, &msg->guest_endpoint_id);
+		    export_guid(__entry->host_id, &msg->host_service_id);
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("sending guest_endpoint_id %pUl, host_service_id %pUl, "
+		      "ret %d",
+		      __entry->guest_id, __entry->host_id, __entry->ret
+		    )
+	);
+
+TRACE_EVENT(vmbus_send_modifychannel,
+	    TP_PROTO(const struct vmbus_channel_modifychannel *msg,
+		     int ret),
+	    TP_ARGS(msg, ret),
+	    TP_STRUCT__entry(
+		    __field(u32, child_relid)
+		    __field(u32, target_vp)
+		    __field(int, ret)
+		    ),
+	    TP_fast_assign(
+		    __entry->child_relid = msg->child_relid;
+		    __entry->target_vp = msg->target_vp;
+		    __entry->ret = ret;
+		    ),
+	    TP_printk("binding child_relid 0x%x to target_vp 0x%x, ret %d",
+		      __entry->child_relid, __entry->target_vp, __entry->ret
+		    )
+	);
+
+DECLARE_EVENT_CLASS(vmbus_channel,
+	TP_PROTO(const struct vmbus_channel *channel),
+	TP_ARGS(channel),
+	TP_STRUCT__entry(__field(u32, relid)),
+	TP_fast_assign(__entry->relid = channel->offermsg.child_relid),
+	TP_printk("relid 0x%x", __entry->relid)
+);
+
+DEFINE_EVENT(vmbus_channel, vmbus_chan_sched,
+	    TP_PROTO(const struct vmbus_channel *channel),
+	    TP_ARGS(channel)
+);
+
+DEFINE_EVENT(vmbus_channel, vmbus_setevent,
+	    TP_PROTO(const struct vmbus_channel *channel),
+	    TP_ARGS(channel)
+);
+
+DEFINE_EVENT(vmbus_channel, vmbus_on_event,
+	    TP_PROTO(const struct vmbus_channel *channel),
+	    TP_ARGS(channel)
+);
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE hv_trace
+#endif /* _HV_TRACE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/drivers/hv/hv_trace_balloon.h b/drivers/hv/hv_trace_balloon.h
new file mode 100644
index 000000000..93082888a
--- /dev/null
+++ b/drivers/hv/hv_trace_balloon.h
@@ -0,0 +1,48 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM hyperv
+
+#if !defined(_HV_TRACE_BALLOON_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _HV_TRACE_BALLOON_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(balloon_status,
+	    TP_PROTO(u64 available, u64 committed,
+		     unsigned long vm_memory_committed,
+		     unsigned long pages_ballooned,
+		     unsigned long pages_added,
+		     unsigned long pages_onlined),
+	    TP_ARGS(available, committed, vm_memory_committed,
+		    pages_ballooned, pages_added, pages_onlined),
+	    TP_STRUCT__entry(
+		    __field(u64, available)
+		    __field(u64, committed)
+		    __field(unsigned long, vm_memory_committed)
+		    __field(unsigned long, pages_ballooned)
+		    __field(unsigned long, pages_added)
+		    __field(unsigned long, pages_onlined)
+		    ),
+	    TP_fast_assign(
+		    __entry->available = available;
+		    __entry->committed = committed;
+		    __entry->vm_memory_committed = vm_memory_committed;
+		    __entry->pages_ballooned = pages_ballooned;
+		    __entry->pages_added = pages_added;
+		    __entry->pages_onlined = pages_onlined;
+		    ),
+	    TP_printk("available %lld, committed %lld; vm_memory_committed %ld;"
+		      " pages_ballooned %ld, pages_added %ld, pages_onlined %ld",
+		      __entry->available, __entry->committed,
+		      __entry->vm_memory_committed, __entry->pages_ballooned,
+		      __entry->pages_added, __entry->pages_onlined
+		    )
+	);
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE hv_trace_balloon
+#endif /* _HV_TRACE_BALLOON_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
new file mode 100644
index 000000000..7e9c8e169
--- /dev/null
+++ b/drivers/hv/hv_util.c
@@ -0,0 +1,815 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2010, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
+#include <linux/reboot.h>
+#include <linux/hyperv.h>
+#include <linux/clockchips.h>
+#include <linux/ptp_clock_kernel.h>
+#include <asm/mshyperv.h>
+
+#include "hyperv_vmbus.h"
+
+#define SD_MAJOR	3
+#define SD_MINOR	0
+#define SD_MINOR_1	1
+#define SD_MINOR_2	2
+#define SD_VERSION_3_1	(SD_MAJOR << 16 | SD_MINOR_1)
+#define SD_VERSION_3_2	(SD_MAJOR << 16 | SD_MINOR_2)
+#define SD_VERSION	(SD_MAJOR << 16 | SD_MINOR)
+
+#define SD_MAJOR_1	1
+#define SD_VERSION_1	(SD_MAJOR_1 << 16 | SD_MINOR)
+
+#define TS_MAJOR	4
+#define TS_MINOR	0
+#define TS_VERSION	(TS_MAJOR << 16 | TS_MINOR)
+
+#define TS_MAJOR_1	1
+#define TS_VERSION_1	(TS_MAJOR_1 << 16 | TS_MINOR)
+
+#define TS_MAJOR_3	3
+#define TS_VERSION_3	(TS_MAJOR_3 << 16 | TS_MINOR)
+
+#define HB_MAJOR	3
+#define HB_MINOR	0
+#define HB_VERSION	(HB_MAJOR << 16 | HB_MINOR)
+
+#define HB_MAJOR_1	1
+#define HB_VERSION_1	(HB_MAJOR_1 << 16 | HB_MINOR)
+
+static int sd_srv_version;
+static int ts_srv_version;
+static int hb_srv_version;
+
+#define SD_VER_COUNT 4
+static const int sd_versions[] = {
+	SD_VERSION_3_2,
+	SD_VERSION_3_1,
+	SD_VERSION,
+	SD_VERSION_1
+};
+
+#define TS_VER_COUNT 3
+static const int ts_versions[] = {
+	TS_VERSION,
+	TS_VERSION_3,
+	TS_VERSION_1
+};
+
+#define HB_VER_COUNT 2
+static const int hb_versions[] = {
+	HB_VERSION,
+	HB_VERSION_1
+};
+
+#define FW_VER_COUNT 2
+static const int fw_versions[] = {
+	UTIL_FW_VERSION,
+	UTIL_WS2K8_FW_VERSION
+};
+
+/*
+ * Send the "hibernate" udev event in a thread context.
+ */
+struct hibernate_work_context {
+	struct work_struct work;
+	struct hv_device *dev;
+};
+
+static struct hibernate_work_context hibernate_context;
+static bool hibernation_supported;
+
+static void send_hibernate_uevent(struct work_struct *work)
+{
+	char *uevent_env[2] = { "EVENT=hibernate", NULL };
+	struct hibernate_work_context *ctx;
+
+	ctx = container_of(work, struct hibernate_work_context, work);
+
+	kobject_uevent_env(&ctx->dev->device.kobj, KOBJ_CHANGE, uevent_env);
+
+	pr_info("Sent hibernation uevent\n");
+}
+
+static int hv_shutdown_init(struct hv_util_service *srv)
+{
+	struct vmbus_channel *channel = srv->channel;
+
+	INIT_WORK(&hibernate_context.work, send_hibernate_uevent);
+	hibernate_context.dev = channel->device_obj;
+
+	hibernation_supported = hv_is_hibernation_supported();
+
+	return 0;
+}
+
+static void shutdown_onchannelcallback(void *context);
+static struct hv_util_service util_shutdown = {
+	.util_cb = shutdown_onchannelcallback,
+	.util_init = hv_shutdown_init,
+};
+
+static int hv_timesync_init(struct hv_util_service *srv);
+static int hv_timesync_pre_suspend(void);
+static void hv_timesync_deinit(void);
+
+static void timesync_onchannelcallback(void *context);
+static struct hv_util_service util_timesynch = {
+	.util_cb = timesync_onchannelcallback,
+	.util_init = hv_timesync_init,
+	.util_pre_suspend = hv_timesync_pre_suspend,
+	.util_deinit = hv_timesync_deinit,
+};
+
+static void heartbeat_onchannelcallback(void *context);
+static struct hv_util_service util_heartbeat = {
+	.util_cb = heartbeat_onchannelcallback,
+};
+
+static struct hv_util_service util_kvp = {
+	.util_cb = hv_kvp_onchannelcallback,
+	.util_init = hv_kvp_init,
+	.util_init_transport = hv_kvp_init_transport,
+	.util_pre_suspend = hv_kvp_pre_suspend,
+	.util_pre_resume = hv_kvp_pre_resume,
+	.util_deinit = hv_kvp_deinit,
+};
+
+static struct hv_util_service util_vss = {
+	.util_cb = hv_vss_onchannelcallback,
+	.util_init = hv_vss_init,
+	.util_init_transport = hv_vss_init_transport,
+	.util_pre_suspend = hv_vss_pre_suspend,
+	.util_pre_resume = hv_vss_pre_resume,
+	.util_deinit = hv_vss_deinit,
+};
+
+static void perform_shutdown(struct work_struct *dummy)
+{
+	orderly_poweroff(true);
+}
+
+static void perform_restart(struct work_struct *dummy)
+{
+	orderly_reboot();
+}
+
+/*
+ * Perform the shutdown operation in a thread context.
+ */
+static DECLARE_WORK(shutdown_work, perform_shutdown);
+
+/*
+ * Perform the restart operation in a thread context.
+ */
+static DECLARE_WORK(restart_work, perform_restart);
+
+static void shutdown_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	struct work_struct *work = NULL;
+	u32 recvlen;
+	u64 requestid;
+	u8  *shut_txf_buf = util_shutdown.recv_buffer;
+
+	struct shutdown_msg_data *shutdown_msg;
+
+	struct icmsg_hdr *icmsghdrp;
+
+	if (vmbus_recvpacket(channel, shut_txf_buf, HV_HYP_PAGE_SIZE, &recvlen, &requestid)) {
+		pr_err_ratelimited("Shutdown request received. Could not read into shut txf buf\n");
+		return;
+	}
+
+	if (!recvlen)
+		return;
+
+	/* Ensure recvlen is big enough to read header data */
+	if (recvlen < ICMSG_HDR) {
+		pr_err_ratelimited("Shutdown request received. Packet length too small: %d\n",
+				   recvlen);
+		return;
+	}
+
+	icmsghdrp = (struct icmsg_hdr *)&shut_txf_buf[sizeof(struct vmbuspipe_hdr)];
+
+	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+		if (vmbus_prep_negotiate_resp(icmsghdrp,
+				shut_txf_buf, recvlen,
+				fw_versions, FW_VER_COUNT,
+				sd_versions, SD_VER_COUNT,
+				NULL, &sd_srv_version)) {
+			pr_info("Shutdown IC version %d.%d\n",
+				sd_srv_version >> 16,
+				sd_srv_version & 0xFFFF);
+		}
+	} else if (icmsghdrp->icmsgtype == ICMSGTYPE_SHUTDOWN) {
+		/* Ensure recvlen is big enough to contain shutdown_msg_data struct */
+		if (recvlen < ICMSG_HDR + sizeof(struct shutdown_msg_data)) {
+			pr_err_ratelimited("Invalid shutdown msg data. Packet length too small: %u\n",
+					   recvlen);
+			return;
+		}
+
+		shutdown_msg = (struct shutdown_msg_data *)&shut_txf_buf[ICMSG_HDR];
+
+		/*
+		 * shutdown_msg->flags can be 0(shut down), 2(reboot),
+		 * or 4(hibernate). It may bitwise-OR 1, which means
+		 * performing the request by force. Linux always tries
+		 * to perform the request by force.
+		 */
+		switch (shutdown_msg->flags) {
+		case 0:
+		case 1:
+			icmsghdrp->status = HV_S_OK;
+			work = &shutdown_work;
+			pr_info("Shutdown request received - graceful shutdown initiated\n");
+			break;
+		case 2:
+		case 3:
+			icmsghdrp->status = HV_S_OK;
+			work = &restart_work;
+			pr_info("Restart request received - graceful restart initiated\n");
+			break;
+		case 4:
+		case 5:
+			pr_info("Hibernation request received\n");
+			icmsghdrp->status = hibernation_supported ?
+				HV_S_OK : HV_E_FAIL;
+			if (hibernation_supported)
+				work = &hibernate_context.work;
+			break;
+		default:
+			icmsghdrp->status = HV_E_FAIL;
+			pr_info("Shutdown request received - Invalid request\n");
+			break;
+		}
+	} else {
+		icmsghdrp->status = HV_E_FAIL;
+		pr_err_ratelimited("Shutdown request received. Invalid msg type: %d\n",
+				   icmsghdrp->icmsgtype);
+	}
+
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+		| ICMSGHDRFLAG_RESPONSE;
+
+	vmbus_sendpacket(channel, shut_txf_buf,
+			 recvlen, requestid,
+			 VM_PKT_DATA_INBAND, 0);
+
+	if (work)
+		schedule_work(work);
+}
+
+/*
+ * Set the host time in a process context.
+ */
+static struct work_struct adj_time_work;
+
+/*
+ * The last time sample, received from the host. PTP device responds to
+ * requests by using this data and the current partition-wide time reference
+ * count.
+ */
+static struct {
+	u64				host_time;
+	u64				ref_time;
+	spinlock_t			lock;
+} host_ts;
+
+static bool timesync_implicit;
+
+module_param(timesync_implicit, bool, 0644);
+MODULE_PARM_DESC(timesync_implicit, "If set treat SAMPLE as SYNC when clock is behind");
+
+static inline u64 reftime_to_ns(u64 reftime)
+{
+	return (reftime - WLTIMEDELTA) * 100;
+}
+
+/*
+ * Hard coded threshold for host timesync delay: 600 seconds
+ */
+static const u64 HOST_TIMESYNC_DELAY_THRESH = 600 * (u64)NSEC_PER_SEC;
+
+static int hv_get_adj_host_time(struct timespec64 *ts)
+{
+	u64 newtime, reftime, timediff_adj;
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&host_ts.lock, flags);
+	reftime = hv_read_reference_counter();
+
+	/*
+	 * We need to let the caller know that last update from host
+	 * is older than the max allowable threshold. clock_gettime()
+	 * and PTP ioctl do not have a documented error that we could
+	 * return for this specific case. Use ESTALE to report this.
+	 */
+	timediff_adj = reftime - host_ts.ref_time;
+	if (timediff_adj * 100 > HOST_TIMESYNC_DELAY_THRESH) {
+		pr_warn_once("TIMESYNC IC: Stale time stamp, %llu nsecs old\n",
+			     (timediff_adj * 100));
+		ret = -ESTALE;
+	}
+
+	newtime = host_ts.host_time + timediff_adj;
+	*ts = ns_to_timespec64(reftime_to_ns(newtime));
+	spin_unlock_irqrestore(&host_ts.lock, flags);
+
+	return ret;
+}
+
+static void hv_set_host_time(struct work_struct *work)
+{
+
+	struct timespec64 ts;
+
+	if (!hv_get_adj_host_time(&ts))
+		do_settimeofday64(&ts);
+}
+
+/*
+ * Due to a bug on Hyper-V hosts, the sync flag may not always be sent on resume.
+ * Force a sync if the guest is behind.
+ */
+static inline bool hv_implicit_sync(u64 host_time)
+{
+	struct timespec64 new_ts;
+	struct timespec64 threshold_ts;
+
+	new_ts = ns_to_timespec64(reftime_to_ns(host_time));
+	ktime_get_real_ts64(&threshold_ts);
+
+	threshold_ts.tv_sec += 5;
+
+	/*
+	 * If guest behind the host by 5 or more seconds.
+	 */
+	if (timespec64_compare(&new_ts, &threshold_ts) >= 0)
+		return true;
+
+	return false;
+}
+
+/*
+ * Synchronize time with host after reboot, restore, etc.
+ *
+ * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
+ * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
+ * message after the timesync channel is opened. Since the hv_utils module is
+ * loaded after hv_vmbus, the first message is usually missed. This bit is
+ * considered a hard request to discipline the clock.
+ *
+ * ICTIMESYNCFLAG_SAMPLE bit indicates a time sample from host. This is
+ * typically used as a hint to the guest. The guest is under no obligation
+ * to discipline the clock.
+ */
+static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 adj_flags)
+{
+	unsigned long flags;
+	u64 cur_reftime;
+
+	/*
+	 * Save the adjusted time sample from the host and the snapshot
+	 * of the current system time.
+	 */
+	spin_lock_irqsave(&host_ts.lock, flags);
+
+	cur_reftime = hv_read_reference_counter();
+	host_ts.host_time = hosttime;
+	host_ts.ref_time = cur_reftime;
+
+	/*
+	 * TimeSync v4 messages contain reference time (guest's Hyper-V
+	 * clocksource read when the time sample was generated), we can
+	 * improve the precision by adding the delta between now and the
+	 * time of generation. For older protocols we set
+	 * reftime == cur_reftime on call.
+	 */
+	host_ts.host_time += (cur_reftime - reftime);
+
+	spin_unlock_irqrestore(&host_ts.lock, flags);
+
+	/* Schedule work to do do_settimeofday64() */
+	if ((adj_flags & ICTIMESYNCFLAG_SYNC) ||
+	    (timesync_implicit && hv_implicit_sync(host_ts.host_time)))
+		schedule_work(&adj_time_work);
+}
+
+/*
+ * Time Sync Channel message handler.
+ */
+static void timesync_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct icmsg_hdr *icmsghdrp;
+	struct ictimesync_data *timedatap;
+	struct ictimesync_ref_data *refdata;
+	u8 *time_txf_buf = util_timesynch.recv_buffer;
+
+	/*
+	 * Drain the ring buffer and use the last packet to update
+	 * host_ts
+	 */
+	while (1) {
+		int ret = vmbus_recvpacket(channel, time_txf_buf,
+					   HV_HYP_PAGE_SIZE, &recvlen,
+					   &requestid);
+		if (ret) {
+			pr_err_ratelimited("TimeSync IC pkt recv failed (Err: %d)\n",
+					   ret);
+			break;
+		}
+
+		if (!recvlen)
+			break;
+
+		/* Ensure recvlen is big enough to read header data */
+		if (recvlen < ICMSG_HDR) {
+			pr_err_ratelimited("Timesync request received. Packet length too small: %d\n",
+					   recvlen);
+			break;
+		}
+
+		icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
+				sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			if (vmbus_prep_negotiate_resp(icmsghdrp,
+						time_txf_buf, recvlen,
+						fw_versions, FW_VER_COUNT,
+						ts_versions, TS_VER_COUNT,
+						NULL, &ts_srv_version)) {
+				pr_info("TimeSync IC version %d.%d\n",
+					ts_srv_version >> 16,
+					ts_srv_version & 0xFFFF);
+			}
+		} else if (icmsghdrp->icmsgtype == ICMSGTYPE_TIMESYNC) {
+			if (ts_srv_version > TS_VERSION_3) {
+				/* Ensure recvlen is big enough to read ictimesync_ref_data */
+				if (recvlen < ICMSG_HDR + sizeof(struct ictimesync_ref_data)) {
+					pr_err_ratelimited("Invalid ictimesync ref data. Length too small: %u\n",
+							   recvlen);
+					break;
+				}
+				refdata = (struct ictimesync_ref_data *)&time_txf_buf[ICMSG_HDR];
+
+				adj_guesttime(refdata->parenttime,
+						refdata->vmreferencetime,
+						refdata->flags);
+			} else {
+				/* Ensure recvlen is big enough to read ictimesync_data */
+				if (recvlen < ICMSG_HDR + sizeof(struct ictimesync_data)) {
+					pr_err_ratelimited("Invalid ictimesync data. Length too small: %u\n",
+							   recvlen);
+					break;
+				}
+				timedatap = (struct ictimesync_data *)&time_txf_buf[ICMSG_HDR];
+
+				adj_guesttime(timedatap->parenttime,
+					      hv_read_reference_counter(),
+					      timedatap->flags);
+			}
+		} else {
+			icmsghdrp->status = HV_E_FAIL;
+			pr_err_ratelimited("Timesync request received. Invalid msg type: %d\n",
+					   icmsghdrp->icmsgtype);
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, time_txf_buf,
+				 recvlen, requestid,
+				 VM_PKT_DATA_INBAND, 0);
+	}
+}
+
+/*
+ * Heartbeat functionality.
+ * Every two seconds, Hyper-V send us a heartbeat request message.
+ * we respond to this message, and Hyper-V knows we are alive.
+ */
+static void heartbeat_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct icmsg_hdr *icmsghdrp;
+	struct heartbeat_msg_data *heartbeat_msg;
+	u8 *hbeat_txf_buf = util_heartbeat.recv_buffer;
+
+	while (1) {
+
+		if (vmbus_recvpacket(channel, hbeat_txf_buf, HV_HYP_PAGE_SIZE,
+				     &recvlen, &requestid)) {
+			pr_err_ratelimited("Heartbeat request received. Could not read into hbeat txf buf\n");
+			return;
+		}
+
+		if (!recvlen)
+			break;
+
+		/* Ensure recvlen is big enough to read header data */
+		if (recvlen < ICMSG_HDR) {
+			pr_err_ratelimited("Heartbeat request received. Packet length too small: %d\n",
+					   recvlen);
+			break;
+		}
+
+		icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
+				sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			if (vmbus_prep_negotiate_resp(icmsghdrp,
+					hbeat_txf_buf, recvlen,
+					fw_versions, FW_VER_COUNT,
+					hb_versions, HB_VER_COUNT,
+					NULL, &hb_srv_version)) {
+
+				pr_info("Heartbeat IC version %d.%d\n",
+					hb_srv_version >> 16,
+					hb_srv_version & 0xFFFF);
+			}
+		} else if (icmsghdrp->icmsgtype == ICMSGTYPE_HEARTBEAT) {
+			/*
+			 * Ensure recvlen is big enough to read seq_num. Reserved area is not
+			 * included in the check as the host may not fill it up entirely
+			 */
+			if (recvlen < ICMSG_HDR + sizeof(u64)) {
+				pr_err_ratelimited("Invalid heartbeat msg data. Length too small: %u\n",
+						   recvlen);
+				break;
+			}
+			heartbeat_msg = (struct heartbeat_msg_data *)&hbeat_txf_buf[ICMSG_HDR];
+
+			heartbeat_msg->seq_num += 1;
+		} else {
+			icmsghdrp->status = HV_E_FAIL;
+			pr_err_ratelimited("Heartbeat request received. Invalid msg type: %d\n",
+					   icmsghdrp->icmsgtype);
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, hbeat_txf_buf,
+				 recvlen, requestid,
+				 VM_PKT_DATA_INBAND, 0);
+	}
+}
+
+#define HV_UTIL_RING_SEND_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
+#define HV_UTIL_RING_RECV_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
+
+static int util_probe(struct hv_device *dev,
+			const struct hv_vmbus_device_id *dev_id)
+{
+	struct hv_util_service *srv =
+		(struct hv_util_service *)dev_id->driver_data;
+	int ret;
+
+	srv->recv_buffer = kmalloc_array(4, HV_HYP_PAGE_SIZE, GFP_KERNEL);
+	if (!srv->recv_buffer)
+		return -ENOMEM;
+	srv->channel = dev->channel;
+	if (srv->util_init) {
+		ret = srv->util_init(srv);
+		if (ret)
+			goto error1;
+	}
+
+	/*
+	 * The set of services managed by the util driver are not performance
+	 * critical and do not need batched reading. Furthermore, some services
+	 * such as KVP can only handle one message from the host at a time.
+	 * Turn off batched reading for all util drivers before we open the
+	 * channel.
+	 */
+	set_channel_read_mode(dev->channel, HV_CALL_DIRECT);
+
+	hv_set_drvdata(dev, srv);
+
+	ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
+			 HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
+			 dev->channel);
+	if (ret)
+		goto error;
+
+	if (srv->util_init_transport) {
+		ret = srv->util_init_transport();
+		if (ret) {
+			vmbus_close(dev->channel);
+			goto error;
+		}
+	}
+	return 0;
+
+error:
+	if (srv->util_deinit)
+		srv->util_deinit();
+error1:
+	kfree(srv->recv_buffer);
+	return ret;
+}
+
+static void util_remove(struct hv_device *dev)
+{
+	struct hv_util_service *srv = hv_get_drvdata(dev);
+
+	if (srv->util_deinit)
+		srv->util_deinit();
+	vmbus_close(dev->channel);
+	kfree(srv->recv_buffer);
+}
+
+/*
+ * When we're in util_suspend(), all the userspace processes have been frozen
+ * (refer to hibernate() -> freeze_processes()). The userspace is thawed only
+ * after the whole resume procedure, including util_resume(), finishes.
+ */
+static int util_suspend(struct hv_device *dev)
+{
+	struct hv_util_service *srv = hv_get_drvdata(dev);
+	int ret = 0;
+
+	if (srv->util_pre_suspend) {
+		ret = srv->util_pre_suspend();
+		if (ret)
+			return ret;
+	}
+
+	vmbus_close(dev->channel);
+
+	return 0;
+}
+
+static int util_resume(struct hv_device *dev)
+{
+	struct hv_util_service *srv = hv_get_drvdata(dev);
+	int ret = 0;
+
+	if (srv->util_pre_resume) {
+		ret = srv->util_pre_resume();
+		if (ret)
+			return ret;
+	}
+
+	ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
+			 HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
+			 dev->channel);
+	return ret;
+}
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Shutdown guid */
+	{ HV_SHUTDOWN_GUID,
+	  .driver_data = (unsigned long)&util_shutdown
+	},
+	/* Time synch guid */
+	{ HV_TS_GUID,
+	  .driver_data = (unsigned long)&util_timesynch
+	},
+	/* Heartbeat guid */
+	{ HV_HEART_BEAT_GUID,
+	  .driver_data = (unsigned long)&util_heartbeat
+	},
+	/* KVP guid */
+	{ HV_KVP_GUID,
+	  .driver_data = (unsigned long)&util_kvp
+	},
+	/* VSS GUID */
+	{ HV_VSS_GUID,
+	  .driver_data = (unsigned long)&util_vss
+	},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+/* The one and only one */
+static  struct hv_driver util_drv = {
+	.name = "hv_utils",
+	.id_table = id_table,
+	.probe =  util_probe,
+	.remove =  util_remove,
+	.suspend = util_suspend,
+	.resume =  util_resume,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+
+static int hv_ptp_enable(struct ptp_clock_info *info,
+			 struct ptp_clock_request *request, int on)
+{
+	return -EOPNOTSUPP;
+}
+
+static int hv_ptp_settime(struct ptp_clock_info *p, const struct timespec64 *ts)
+{
+	return -EOPNOTSUPP;
+}
+
+static int hv_ptp_adjfine(struct ptp_clock_info *ptp, long delta)
+{
+	return -EOPNOTSUPP;
+}
+static int hv_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	return -EOPNOTSUPP;
+}
+
+static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
+{
+	return hv_get_adj_host_time(ts);
+}
+
+static struct ptp_clock_info ptp_hyperv_info = {
+	.name		= "hyperv",
+	.enable         = hv_ptp_enable,
+	.adjtime        = hv_ptp_adjtime,
+	.adjfine        = hv_ptp_adjfine,
+	.gettime64      = hv_ptp_gettime,
+	.settime64      = hv_ptp_settime,
+	.owner		= THIS_MODULE,
+};
+
+static struct ptp_clock *hv_ptp_clock;
+
+static int hv_timesync_init(struct hv_util_service *srv)
+{
+	spin_lock_init(&host_ts.lock);
+
+	INIT_WORK(&adj_time_work, hv_set_host_time);
+
+	/*
+	 * ptp_clock_register() returns NULL when CONFIG_PTP_1588_CLOCK is
+	 * disabled but the driver is still useful without the PTP device
+	 * as it still handles the ICTIMESYNCFLAG_SYNC case.
+	 */
+	hv_ptp_clock = ptp_clock_register(&ptp_hyperv_info, NULL);
+	if (IS_ERR_OR_NULL(hv_ptp_clock)) {
+		pr_err("cannot register PTP clock: %d\n",
+		       PTR_ERR_OR_ZERO(hv_ptp_clock));
+		hv_ptp_clock = NULL;
+	}
+
+	return 0;
+}
+
+static void hv_timesync_cancel_work(void)
+{
+	cancel_work_sync(&adj_time_work);
+}
+
+static int hv_timesync_pre_suspend(void)
+{
+	hv_timesync_cancel_work();
+	return 0;
+}
+
+static void hv_timesync_deinit(void)
+{
+	if (hv_ptp_clock)
+		ptp_clock_unregister(hv_ptp_clock);
+
+	hv_timesync_cancel_work();
+}
+
+static int __init init_hyperv_utils(void)
+{
+	pr_info("Registering HyperV Utility Driver\n");
+
+	return vmbus_driver_register(&util_drv);
+}
+
+static void exit_hyperv_utils(void)
+{
+	pr_info("De-Registered HyperV Utility Driver\n");
+
+	vmbus_driver_unregister(&util_drv);
+}
+
+module_init(init_hyperv_utils);
+module_exit(exit_hyperv_utils);
+
+MODULE_DESCRIPTION("Hyper-V Utilities");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hv/hv_utils_transport.c b/drivers/hv/hv_utils_transport.c
new file mode 100644
index 000000000..c3be5c570
--- /dev/null
+++ b/drivers/hv/hv_utils_transport.c
@@ -0,0 +1,350 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kernel/userspace transport abstraction for Hyper-V util driver.
+ *
+ * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+
+#include "hyperv_vmbus.h"
+#include "hv_utils_transport.h"
+
+static DEFINE_SPINLOCK(hvt_list_lock);
+static LIST_HEAD(hvt_list);
+
+static void hvt_reset(struct hvutil_transport *hvt)
+{
+	kfree(hvt->outmsg);
+	hvt->outmsg = NULL;
+	hvt->outmsg_len = 0;
+	if (hvt->on_reset)
+		hvt->on_reset();
+}
+
+static ssize_t hvt_op_read(struct file *file, char __user *buf,
+			   size_t count, loff_t *ppos)
+{
+	struct hvutil_transport *hvt;
+	int ret;
+
+	hvt = container_of(file->f_op, struct hvutil_transport, fops);
+
+	if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
+				     hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
+		return -EINTR;
+
+	mutex_lock(&hvt->lock);
+
+	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
+		ret = -EBADF;
+		goto out_unlock;
+	}
+
+	if (!hvt->outmsg) {
+		ret = -EAGAIN;
+		goto out_unlock;
+	}
+
+	if (count < hvt->outmsg_len) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
+		ret = hvt->outmsg_len;
+	else
+		ret = -EFAULT;
+
+	kfree(hvt->outmsg);
+	hvt->outmsg = NULL;
+	hvt->outmsg_len = 0;
+
+	if (hvt->on_read)
+		hvt->on_read();
+	hvt->on_read = NULL;
+
+out_unlock:
+	mutex_unlock(&hvt->lock);
+	return ret;
+}
+
+static ssize_t hvt_op_write(struct file *file, const char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	struct hvutil_transport *hvt;
+	u8 *inmsg;
+	int ret;
+
+	hvt = container_of(file->f_op, struct hvutil_transport, fops);
+
+	inmsg = memdup_user(buf, count);
+	if (IS_ERR(inmsg))
+		return PTR_ERR(inmsg);
+
+	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
+		ret = -EBADF;
+	else
+		ret = hvt->on_msg(inmsg, count);
+
+	kfree(inmsg);
+
+	return ret ? ret : count;
+}
+
+static __poll_t hvt_op_poll(struct file *file, poll_table *wait)
+{
+	struct hvutil_transport *hvt;
+
+	hvt = container_of(file->f_op, struct hvutil_transport, fops);
+
+	poll_wait(file, &hvt->outmsg_q, wait);
+
+	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
+		return EPOLLERR | EPOLLHUP;
+
+	if (hvt->outmsg_len > 0)
+		return EPOLLIN | EPOLLRDNORM;
+
+	return 0;
+}
+
+static int hvt_op_open(struct inode *inode, struct file *file)
+{
+	struct hvutil_transport *hvt;
+	int ret = 0;
+	bool issue_reset = false;
+
+	hvt = container_of(file->f_op, struct hvutil_transport, fops);
+
+	mutex_lock(&hvt->lock);
+
+	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
+		ret = -EBADF;
+	} else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
+		/*
+		 * Switching to CHARDEV mode. We switch bach to INIT when
+		 * device gets released.
+		 */
+		hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
+	} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
+		/*
+		 * We're switching from netlink communication to using char
+		 * device. Issue the reset first.
+		 */
+		issue_reset = true;
+		hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
+	} else {
+		ret = -EBUSY;
+	}
+
+	if (issue_reset)
+		hvt_reset(hvt);
+
+	mutex_unlock(&hvt->lock);
+
+	return ret;
+}
+
+static void hvt_transport_free(struct hvutil_transport *hvt)
+{
+	misc_deregister(&hvt->mdev);
+	kfree(hvt->outmsg);
+	kfree(hvt);
+}
+
+static int hvt_op_release(struct inode *inode, struct file *file)
+{
+	struct hvutil_transport *hvt;
+	int mode_old;
+
+	hvt = container_of(file->f_op, struct hvutil_transport, fops);
+
+	mutex_lock(&hvt->lock);
+	mode_old = hvt->mode;
+	if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
+		hvt->mode = HVUTIL_TRANSPORT_INIT;
+	/*
+	 * Cleanup message buffers to avoid spurious messages when the daemon
+	 * connects back.
+	 */
+	hvt_reset(hvt);
+
+	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
+		complete(&hvt->release);
+
+	mutex_unlock(&hvt->lock);
+
+	return 0;
+}
+
+static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
+{
+	struct hvutil_transport *hvt, *hvt_found = NULL;
+
+	spin_lock(&hvt_list_lock);
+	list_for_each_entry(hvt, &hvt_list, list) {
+		if (hvt->cn_id.idx == msg->id.idx &&
+		    hvt->cn_id.val == msg->id.val) {
+			hvt_found = hvt;
+			break;
+		}
+	}
+	spin_unlock(&hvt_list_lock);
+	if (!hvt_found) {
+		pr_warn("%s: spurious message received!\n", __func__);
+		return;
+	}
+
+	/*
+	 * Switching to NETLINK mode. Switching to CHARDEV happens when someone
+	 * opens the device.
+	 */
+	mutex_lock(&hvt->lock);
+	if (hvt->mode == HVUTIL_TRANSPORT_INIT)
+		hvt->mode = HVUTIL_TRANSPORT_NETLINK;
+
+	if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
+		hvt_found->on_msg(msg->data, msg->len);
+	else
+		pr_warn("%s: unexpected netlink message!\n", __func__);
+	mutex_unlock(&hvt->lock);
+}
+
+int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
+			  void (*on_read_cb)(void))
+{
+	struct cn_msg *cn_msg;
+	int ret = 0;
+
+	if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
+	    hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
+		return -EINVAL;
+	} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
+		cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
+		if (!cn_msg)
+			return -ENOMEM;
+		cn_msg->id.idx = hvt->cn_id.idx;
+		cn_msg->id.val = hvt->cn_id.val;
+		cn_msg->len = len;
+		memcpy(cn_msg->data, msg, len);
+		ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
+		kfree(cn_msg);
+		/*
+		 * We don't know when netlink messages are delivered but unlike
+		 * in CHARDEV mode we're not blocked and we can send next
+		 * messages right away.
+		 */
+		if (on_read_cb)
+			on_read_cb();
+		return ret;
+	}
+	/* HVUTIL_TRANSPORT_CHARDEV */
+	mutex_lock(&hvt->lock);
+	if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (hvt->outmsg) {
+		/* Previous message wasn't received */
+		ret = -EFAULT;
+		goto out_unlock;
+	}
+	hvt->outmsg = kzalloc(len, GFP_KERNEL);
+	if (hvt->outmsg) {
+		memcpy(hvt->outmsg, msg, len);
+		hvt->outmsg_len = len;
+		hvt->on_read = on_read_cb;
+		wake_up_interruptible(&hvt->outmsg_q);
+	} else {
+		ret = -ENOMEM;
+	}
+out_unlock:
+	mutex_unlock(&hvt->lock);
+	return ret;
+}
+
+struct hvutil_transport *hvutil_transport_init(const char *name,
+					       u32 cn_idx, u32 cn_val,
+					       int (*on_msg)(void *, int),
+					       void (*on_reset)(void))
+{
+	struct hvutil_transport *hvt;
+
+	hvt = kzalloc_obj(*hvt);
+	if (!hvt)
+		return NULL;
+
+	hvt->cn_id.idx = cn_idx;
+	hvt->cn_id.val = cn_val;
+
+	hvt->mdev.minor = MISC_DYNAMIC_MINOR;
+	hvt->mdev.name = name;
+
+	hvt->fops.owner = THIS_MODULE;
+	hvt->fops.read = hvt_op_read;
+	hvt->fops.write = hvt_op_write;
+	hvt->fops.poll = hvt_op_poll;
+	hvt->fops.open = hvt_op_open;
+	hvt->fops.release = hvt_op_release;
+
+	hvt->mdev.fops = &hvt->fops;
+
+	init_waitqueue_head(&hvt->outmsg_q);
+	mutex_init(&hvt->lock);
+	init_completion(&hvt->release);
+
+	spin_lock(&hvt_list_lock);
+	list_add(&hvt->list, &hvt_list);
+	spin_unlock(&hvt_list_lock);
+
+	hvt->on_msg = on_msg;
+	hvt->on_reset = on_reset;
+
+	if (misc_register(&hvt->mdev))
+		goto err_free_hvt;
+
+	/* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
+	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
+	    cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
+		goto err_free_hvt;
+
+	return hvt;
+
+err_free_hvt:
+	spin_lock(&hvt_list_lock);
+	list_del(&hvt->list);
+	spin_unlock(&hvt_list_lock);
+	kfree(hvt);
+	return NULL;
+}
+
+void hvutil_transport_destroy(struct hvutil_transport *hvt)
+{
+	int mode_old;
+
+	mutex_lock(&hvt->lock);
+	mode_old = hvt->mode;
+	hvt->mode = HVUTIL_TRANSPORT_DESTROY;
+	wake_up_interruptible(&hvt->outmsg_q);
+	mutex_unlock(&hvt->lock);
+
+	/*
+	 * In case we were in 'chardev' mode we still have an open fd so we
+	 * have to defer freeing the device. Netlink interface can be freed
+	 * now.
+	 */
+	spin_lock(&hvt_list_lock);
+	list_del(&hvt->list);
+	spin_unlock(&hvt_list_lock);
+	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
+		cn_del_callback(&hvt->cn_id);
+
+	if (mode_old == HVUTIL_TRANSPORT_CHARDEV)
+		wait_for_completion(&hvt->release);
+
+	hvt_transport_free(hvt);
+}
diff --git a/drivers/hv/hv_utils_transport.h b/drivers/hv/hv_utils_transport.h
new file mode 100644
index 000000000..1c162393c
--- /dev/null
+++ b/drivers/hv/hv_utils_transport.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Kernel/userspace transport abstraction for Hyper-V util driver.
+ *
+ * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
+ */
+
+#ifndef _HV_UTILS_TRANSPORT_H
+#define _HV_UTILS_TRANSPORT_H
+
+#include <linux/connector.h>
+#include <linux/miscdevice.h>
+
+enum hvutil_transport_mode {
+	HVUTIL_TRANSPORT_INIT = 0,
+	HVUTIL_TRANSPORT_NETLINK,
+	HVUTIL_TRANSPORT_CHARDEV,
+	HVUTIL_TRANSPORT_DESTROY,
+};
+
+struct hvutil_transport {
+	int mode;                           /* hvutil_transport_mode */
+	struct file_operations fops;        /* file operations */
+	struct miscdevice mdev;             /* misc device */
+	struct cb_id cn_id;                 /* CN_*_IDX/CN_*_VAL */
+	struct list_head list;              /* hvt_list */
+	int (*on_msg)(void *, int);         /* callback on new user message */
+	void (*on_reset)(void);             /* callback when userspace drops */
+	void (*on_read)(void);              /* callback on message read */
+	u8 *outmsg;                         /* message to the userspace */
+	int outmsg_len;                     /* its length */
+	wait_queue_head_t outmsg_q;         /* poll/read wait queue */
+	struct mutex lock;                  /* protects struct members */
+	struct completion release;          /* synchronize with fd release */
+};
+
+struct hvutil_transport *hvutil_transport_init(const char *name,
+					       u32 cn_idx, u32 cn_val,
+					       int (*on_msg)(void *, int),
+					       void (*on_reset)(void));
+int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
+			  void (*on_read_cb)(void));
+void hvutil_transport_destroy(struct hvutil_transport *hvt);
+
+#endif /* _HV_UTILS_TRANSPORT_H */
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
new file mode 100644
index 000000000..33923621a
--- /dev/null
+++ b/drivers/hv/hyperv_vmbus.h
@@ -0,0 +1,554 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *
+ * Copyright (c) 2011, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ */
+
+#ifndef _HYPERV_VMBUS_H
+#define _HYPERV_VMBUS_H
+
+#include <linux/list.h>
+#include <linux/bitops.h>
+#include <asm/sync_bitops.h>
+#include <asm/mshyperv.h>
+#include <linux/atomic.h>
+#include <linux/hyperv.h>
+#include <linux/interrupt.h>
+#include <hyperv/hvhdk.h>
+
+#include "hv_trace.h"
+
+/*
+ * Timeout for services such as KVP and fcopy.
+ */
+#define HV_UTIL_TIMEOUT 30
+
+/*
+ * Timeout for guest-host handshake for services.
+ */
+#define HV_UTIL_NEGO_TIMEOUT 55
+
+void vmbus_isr(void);
+
+/* Definitions for the monitored notification facility */
+union hv_monitor_trigger_group {
+	u64 as_uint64;
+	struct {
+		u32 pending;
+		u32 armed;
+	};
+};
+
+struct hv_monitor_parameter {
+	union hv_connection_id connectionid;
+	u16 flagnumber;
+	u16 rsvdz;
+};
+
+union hv_monitor_trigger_state {
+	u32 asu32;
+
+	struct {
+		u32 group_enable:4;
+		u32 rsvdz:28;
+	};
+};
+
+/* struct hv_monitor_page Layout */
+/* ------------------------------------------------------ */
+/* | 0   | TriggerState (4 bytes) | Rsvd1 (4 bytes)     | */
+/* | 8   | TriggerGroup[0]                              | */
+/* | 10  | TriggerGroup[1]                              | */
+/* | 18  | TriggerGroup[2]                              | */
+/* | 20  | TriggerGroup[3]                              | */
+/* | 28  | Rsvd2[0]                                     | */
+/* | 30  | Rsvd2[1]                                     | */
+/* | 38  | Rsvd2[2]                                     | */
+/* | 40  | NextCheckTime[0][0]    | NextCheckTime[0][1] | */
+/* | ...                                                | */
+/* | 240 | Latency[0][0..3]                             | */
+/* | 340 | Rsvz3[0]                                     | */
+/* | 440 | Parameter[0][0]                              | */
+/* | 448 | Parameter[0][1]                              | */
+/* | ...                                                | */
+/* | 840 | Rsvd4[0]                                     | */
+/* ------------------------------------------------------ */
+struct hv_monitor_page {
+	union hv_monitor_trigger_state trigger_state;
+	u32 rsvdz1;
+
+	union hv_monitor_trigger_group trigger_group[4];
+	u64 rsvdz2[3];
+
+	s32 next_checktime[4][32];
+
+	u16 latency[4][32];
+	u64 rsvdz3[32];
+
+	struct hv_monitor_parameter parameter[4][32];
+
+	u8 rsvdz4[1984];
+};
+
+#define HV_HYPERCALL_PARAM_ALIGN	sizeof(u64)
+
+/* Definition of the hv_post_message hypercall input structure. */
+struct hv_input_post_message {
+	union hv_connection_id connectionid;
+	u32 reserved;
+	u32 message_type;
+	u32 payload_size;
+	u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
+};
+
+
+enum {
+	VMBUS_MESSAGE_CONNECTION_ID	= 1,
+	VMBUS_MESSAGE_CONNECTION_ID_4	= 4,
+	/* VTL2 redirect connection ID for INITIATE_CONTACT. */
+	VMBUS_MESSAGE_CONNECTION_ID_REDIRECT = 0x800074,
+	VMBUS_MESSAGE_PORT_ID		= 1,
+	VMBUS_EVENT_CONNECTION_ID	= 2,
+	VMBUS_EVENT_PORT_ID		= 2,
+	VMBUS_MONITOR_CONNECTION_ID	= 3,
+	VMBUS_MONITOR_PORT_ID		= 3,
+	VMBUS_MESSAGE_SINT		= 2,
+};
+
+/*
+ * Per cpu state for channel handling
+ */
+struct hv_per_cpu_context {
+	/*
+	 * SynIC pages for communicating with the host.
+	 *
+	 * These pages are accessible to the host partition and the hypervisor.
+	 * They may be used for exchanging data with the host partition and the
+	 * hypervisor even when they aren't trusted yet the guest partition
+	 * must be prepared to handle the malicious behavior.
+	 */
+	void *hyp_synic_message_page;
+	void *hyp_synic_event_page;
+	/*
+	 * SynIC pages for communicating with the paravisor.
+	 *
+	 * These pages may be accessed from within the guest partition only in
+	 * CoCo VMs. Neither the host partition nor the hypervisor can access
+	 * these pages in that case; they are used for exchanging data with the
+	 * paravisor.
+	 */
+	void *para_synic_message_page;
+	void *para_synic_event_page;
+
+	/*
+	 * The page is only used in hv_post_message() for a TDX VM (with the
+	 * paravisor) to post a messages to Hyper-V: when such a VM calls
+	 * HVCALL_POST_MESSAGE, it can't use the hyperv_pcpu_input_arg (which
+	 * is encrypted in such a VM) as the hypercall input page, because
+	 * the input page for HVCALL_POST_MESSAGE must be decrypted in such a
+	 * VM, so post_msg_page (which is decrypted in hv_synic_alloc()) is
+	 * introduced for this purpose. See hyperv_init() for more comments.
+	 */
+	void *post_msg_page;
+
+	/*
+	 * Starting with win8, we can take channel interrupts on any CPU;
+	 * we will manage the tasklet that handles events messages on a per CPU
+	 * basis.
+	 */
+	struct tasklet_struct msg_dpc;
+};
+
+struct hv_context {
+	/* We only support running on top of Hyper-V
+	 * So at this point this really can only contain the Hyper-V ID
+	 */
+	u64 guestid;
+
+	struct hv_per_cpu_context __percpu *cpu_context;
+
+	/*
+	 * To manage allocations in a NUMA node.
+	 * Array indexed by numa node ID.
+	 */
+	struct cpumask *hv_numa_map;
+};
+
+extern struct hv_context hv_context;
+
+/* Hv Interface */
+
+extern int hv_init(void);
+
+extern int hv_post_message(union hv_connection_id connection_id,
+			 enum hv_message_type message_type,
+			 void *payload, size_t payload_size);
+
+extern int hv_synic_alloc(void);
+
+extern void hv_synic_free(void);
+
+extern void hv_hyp_synic_enable_regs(unsigned int cpu);
+extern int hv_synic_init(unsigned int cpu);
+
+extern void hv_hyp_synic_disable_regs(unsigned int cpu);
+extern int hv_synic_cleanup(unsigned int cpu);
+
+/* Interface */
+
+void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
+
+int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
+		       struct page *pages, u32 pagecnt, u32 max_pkt_size,
+			   bool confidential);
+
+void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
+
+int hv_ringbuffer_write(struct vmbus_channel *channel,
+			const struct kvec *kv_list, u32 kv_count,
+			u64 requestid, u64 *trans_id);
+
+int hv_ringbuffer_read(struct vmbus_channel *channel,
+		       void *buffer, u32 buflen, u32 *buffer_actual_len,
+		       u64 *requestid, bool raw);
+
+/*
+ * The Maximum number of channels (16384) is determined by the size of the
+ * interrupt page, which is HV_HYP_PAGE_SIZE. 1/2 of HV_HYP_PAGE_SIZE is to
+ * send endpoint interrupts, and the other is to receive endpoint interrupts.
+ */
+#define MAX_NUM_CHANNELS	((HV_HYP_PAGE_SIZE >> 1) << 3)
+
+/* The value here must be in multiple of 32 */
+#define MAX_NUM_CHANNELS_SUPPORTED	256
+
+#define MAX_CHANNEL_RELIDS					\
+	max(MAX_NUM_CHANNELS_SUPPORTED, HV_EVENT_FLAGS_COUNT)
+
+enum vmbus_connect_state {
+	DISCONNECTED,
+	CONNECTING,
+	CONNECTED,
+	DISCONNECTING
+};
+
+#define MAX_SIZE_CHANNEL_MESSAGE	HV_MESSAGE_PAYLOAD_BYTE_COUNT
+
+/*
+ * The CPU that Hyper-V will interrupt for VMBUS messages, such as
+ * CHANNELMSG_OFFERCHANNEL and CHANNELMSG_RESCIND_CHANNELOFFER.
+ */
+#define VMBUS_CONNECT_CPU	0
+
+struct vmbus_connection {
+	u32 msg_conn_id;
+
+	atomic_t offer_in_progress;
+
+	enum vmbus_connect_state conn_state;
+
+	atomic_t next_gpadl_handle;
+
+	struct completion  unload_event;
+	/*
+	 * Represents channel interrupts. Each bit position represents a
+	 * channel.  When a channel sends an interrupt via VMBUS, it finds its
+	 * bit in the sendInterruptPage, set it and calls Hv to generate a port
+	 * event. The other end receives the port event and parse the
+	 * recvInterruptPage to see which bit is set
+	 */
+	void *int_page;
+	void *send_int_page;
+	void *recv_int_page;
+
+	/*
+	 * 2 pages - 1st page for parent->child notification and 2nd
+	 * is child->parent notification
+	 */
+	struct hv_monitor_page *monitor_pages[2];
+	struct list_head chn_msg_list;
+	spinlock_t channelmsg_lock;
+
+	/* List of channels */
+	struct list_head chn_list;
+	struct mutex channel_mutex;
+
+	/* Array of channel pointers, indexed by relid */
+	struct vmbus_channel **channels;
+	u32 relid_hiwater;
+
+	/*
+	 * An offer message is handled first on the work_queue, and then
+	 * is further handled on handle_primary_chan_wq or
+	 * handle_sub_chan_wq.
+	 */
+	struct workqueue_struct *work_queue;
+	struct workqueue_struct *handle_primary_chan_wq;
+	struct workqueue_struct *handle_sub_chan_wq;
+	struct workqueue_struct *rescind_work_queue;
+
+	/*
+	 * On suspension of the vmbus, the accumulated offer messages
+	 * must be dropped.
+	 */
+	bool ignore_any_offer_msg;
+
+	/*
+	 * The number of sub-channels and hv_sock channels that should be
+	 * cleaned up upon suspend: sub-channels will be re-created upon
+	 * resume, and hv_sock channels should not survive suspend.
+	 */
+	atomic_t nr_chan_close_on_suspend;
+	/*
+	 * vmbus_bus_suspend() waits for "nr_chan_close_on_suspend" to
+	 * drop to zero.
+	 */
+	struct completion ready_for_suspend_event;
+
+	/*
+	 * Completed once the host has offered all boot-time channels.
+	 * Note that some channels may still be under process on a workqueue.
+	 */
+	struct completion all_offers_delivered_event;
+};
+
+
+struct vmbus_msginfo {
+	/* Bookkeeping stuff */
+	struct list_head msglist_entry;
+
+	/* The message itself */
+	unsigned char msg[];
+};
+
+
+extern struct vmbus_connection vmbus_connection;
+
+int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version);
+
+static inline void vmbus_send_interrupt(u32 relid)
+{
+	sync_set_bit(relid, vmbus_connection.send_int_page);
+}
+
+enum vmbus_message_handler_type {
+	/* The related handler can sleep. */
+	VMHT_BLOCKING = 0,
+
+	/* The related handler must NOT sleep. */
+	VMHT_NON_BLOCKING = 1,
+};
+
+struct vmbus_channel_message_table_entry {
+	enum vmbus_channel_message_type message_type;
+	enum vmbus_message_handler_type handler_type;
+	void (*message_handler)(struct vmbus_channel_message_header *msg);
+	u32 min_payload_len;
+};
+
+extern const struct vmbus_channel_message_table_entry
+	channel_message_table[CHANNELMSG_COUNT];
+
+
+/* General vmbus interface */
+
+bool vmbus_is_confidential(void);
+
+#if IS_ENABLED(CONFIG_HYPERV_VMBUS)
+/* Free the message slot and signal end-of-message if required */
+static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
+{
+	/*
+	 * On crash we're reading some other CPU's message page and we need
+	 * to be careful: this other CPU may already had cleared the header
+	 * and the host may already had delivered some other message there.
+	 * In case we blindly write msg->header.message_type we're going
+	 * to lose it. We can still lose a message of the same type but
+	 * we count on the fact that there can only be one
+	 * CHANNELMSG_UNLOAD_RESPONSE and we don't care about other messages
+	 * on crash.
+	 */
+	if (!try_cmpxchg(&msg->header.message_type,
+			 &old_msg_type, HVMSG_NONE))
+		return;
+
+	/*
+	 * The cmpxchg() above does an implicit memory barrier to
+	 * ensure the write to MessageType (ie set to
+	 * HVMSG_NONE) happens before we read the
+	 * MessagePending and EOMing. Otherwise, the EOMing
+	 * will not deliver any more messages since there is
+	 * no empty slot
+	 */
+	if (msg->header.message_flags.msg_pending) {
+		/*
+		 * This will cause message queue rescan to
+		 * possibly deliver another msg from the
+		 * hypervisor
+		 */
+		if (vmbus_is_confidential())
+			hv_para_set_synic_register(HV_MSR_EOM, 0);
+		else
+			hv_set_msr(HV_MSR_EOM, 0);
+	}
+}
+
+extern int vmbus_interrupt;
+extern int vmbus_irq;
+#endif /* CONFIG_HYPERV_VMBUS */
+
+struct hv_device *vmbus_device_create(const guid_t *type,
+				      const guid_t *instance,
+				      struct vmbus_channel *channel);
+
+int vmbus_device_register(struct hv_device *child_device_obj);
+void vmbus_device_unregister(struct hv_device *device_obj);
+int vmbus_add_channel_kobj(struct hv_device *device_obj,
+			   struct vmbus_channel *channel);
+
+void vmbus_remove_channel_attr_group(struct vmbus_channel *channel);
+
+void vmbus_channel_map_relid(struct vmbus_channel *channel);
+void vmbus_channel_unmap_relid(struct vmbus_channel *channel);
+
+struct vmbus_channel *relid2channel(u32 relid);
+
+void vmbus_free_channels(void);
+
+/* Connection interface */
+
+int vmbus_connect(void);
+void vmbus_disconnect(void);
+
+int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep);
+
+void vmbus_on_event(unsigned long data);
+void vmbus_on_msg_dpc(unsigned long data);
+
+int hv_kvp_init(struct hv_util_service *srv);
+int hv_kvp_init_transport(void);
+void hv_kvp_deinit(void);
+int hv_kvp_pre_suspend(void);
+int hv_kvp_pre_resume(void);
+void hv_kvp_onchannelcallback(void *context);
+
+int hv_vss_init(struct hv_util_service *srv);
+int hv_vss_init_transport(void);
+void hv_vss_deinit(void);
+int hv_vss_pre_suspend(void);
+int hv_vss_pre_resume(void);
+void hv_vss_onchannelcallback(void *context);
+
+static inline void hv_poll_channel(struct vmbus_channel *channel,
+				   void (*cb)(void *))
+{
+	if (!channel)
+		return;
+	cb(channel);
+}
+
+enum hvutil_device_state {
+	HVUTIL_DEVICE_INIT = 0,  /* driver is loaded, waiting for userspace */
+	HVUTIL_READY,            /* userspace is registered */
+	HVUTIL_HOSTMSG_RECEIVED, /* message from the host was received */
+	HVUTIL_USERSPACE_REQ,    /* request to userspace was sent */
+	HVUTIL_USERSPACE_RECV,   /* reply from userspace was received */
+	HVUTIL_DEVICE_DYING,     /* driver unload is in progress */
+};
+
+enum delay {
+	INTERRUPT_DELAY = 0,
+	MESSAGE_DELAY   = 1,
+};
+
+extern const struct vmbus_device vmbus_devs[];
+
+static inline bool hv_is_perf_channel(struct vmbus_channel *channel)
+{
+	return vmbus_devs[channel->device_id].perf_device;
+}
+
+static inline size_t hv_dev_ring_size(struct vmbus_channel *channel)
+{
+	return vmbus_devs[channel->device_id].pref_ring_size;
+}
+
+static inline bool hv_is_allocated_cpu(unsigned int cpu)
+{
+	struct vmbus_channel *channel, *sc;
+
+	lockdep_assert_held(&vmbus_connection.channel_mutex);
+	/*
+	 * List additions/deletions as well as updates of the target CPUs are
+	 * protected by channel_mutex.
+	 */
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (!hv_is_perf_channel(channel))
+			continue;
+		if (channel->target_cpu == cpu)
+			return true;
+		list_for_each_entry(sc, &channel->sc_list, sc_list) {
+			if (sc->target_cpu == cpu)
+				return true;
+		}
+	}
+	return false;
+}
+
+static inline void hv_set_allocated_cpu(unsigned int cpu)
+{
+	cpumask_set_cpu(cpu, &hv_context.hv_numa_map[cpu_to_node(cpu)]);
+}
+
+static inline void hv_clear_allocated_cpu(unsigned int cpu)
+{
+	if (hv_is_allocated_cpu(cpu))
+		return;
+	cpumask_clear_cpu(cpu, &hv_context.hv_numa_map[cpu_to_node(cpu)]);
+}
+
+static inline void hv_update_allocated_cpus(unsigned int old_cpu,
+					  unsigned int new_cpu)
+{
+	hv_set_allocated_cpu(new_cpu);
+	hv_clear_allocated_cpu(old_cpu);
+}
+
+#ifdef CONFIG_HYPERV_TESTING
+
+int hv_debug_add_dev_dir(struct hv_device *dev);
+void hv_debug_rm_dev_dir(struct hv_device *dev);
+void hv_debug_rm_all_dir(void);
+int hv_debug_init(void);
+void hv_debug_delay_test(struct vmbus_channel *channel, enum delay delay_type);
+
+#else /* CONFIG_HYPERV_TESTING */
+
+static inline void hv_debug_rm_dev_dir(struct hv_device *dev) {};
+static inline void hv_debug_rm_all_dir(void) {};
+static inline void hv_debug_delay_test(struct vmbus_channel *channel,
+				       enum delay delay_type) {};
+static inline int hv_debug_init(void)
+{
+	return -1;
+}
+
+static inline int hv_debug_add_dev_dir(struct hv_device *dev)
+{
+	return -1;
+}
+
+#endif /* CONFIG_HYPERV_TESTING */
+
+/* Create and remove sysfs entry for memory mapped ring buffers for a channel */
+int hv_create_ring_sysfs(struct vmbus_channel *channel,
+			 int (*hv_mmap_prepare_ring_buffer)(struct vmbus_channel *channel,
+							    struct vm_area_desc *desc));
+int hv_remove_ring_sysfs(struct vmbus_channel *channel);
+
+#endif /* _HYPERV_VMBUS_H */
diff --git a/drivers/hv/mshv.h b/drivers/hv/mshv.h
new file mode 100644
index 000000000..d4813df92
--- /dev/null
+++ b/drivers/hv/mshv.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ */
+
+#ifndef _MSHV_H_
+#define _MSHV_H_
+
+#include <linux/stddef.h>
+#include <linux/string.h>
+#include <hyperv/hvhdk.h>
+
+#define mshv_field_nonzero(STRUCT, MEMBER) \
+	memchr_inv(&((STRUCT).MEMBER), \
+		   0, sizeof_field(typeof(STRUCT), MEMBER))
+
+int hv_call_get_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+			     union hv_input_vtl input_vtl,
+			     struct hv_register_assoc *registers);
+
+int hv_call_set_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+			     union hv_input_vtl input_vtl,
+			     struct hv_register_assoc *registers);
+
+int hv_call_get_partition_property(u64 partition_id, u64 property_code,
+				   u64 *property_value);
+
+#endif /* _MSHV_H */
diff --git a/drivers/hv/mshv_common.c b/drivers/hv/mshv_common.c
new file mode 100644
index 000000000..63f09bb51
--- /dev/null
+++ b/drivers/hv/mshv_common.c
@@ -0,0 +1,241 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024, Microsoft Corporation.
+ *
+ * This file contains functions that will be called from one or more modules.
+ * If any of these modules are configured to build, this file is built and just
+ * statically linked in.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <asm/mshyperv.h>
+#include <linux/resume_user_mode.h>
+#include <linux/export.h>
+#include <linux/acpi.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+
+#include "mshv.h"
+
+#define HV_GET_REGISTER_BATCH_SIZE	\
+	(HV_HYP_PAGE_SIZE / sizeof(union hv_register_value))
+#define HV_SET_REGISTER_BATCH_SIZE	\
+	((HV_HYP_PAGE_SIZE - sizeof(struct hv_input_set_vp_registers)) \
+		/ sizeof(struct hv_register_assoc))
+
+int hv_call_get_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+			     union hv_input_vtl input_vtl,
+			     struct hv_register_assoc *registers)
+{
+	struct hv_input_get_vp_registers *input_page;
+	union hv_register_value *output_page;
+	u16 completed = 0;
+	unsigned long remaining = count;
+	int rep_count, i;
+	u64 status = HV_STATUS_SUCCESS;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	input_page->partition_id = partition_id;
+	input_page->vp_index = vp_index;
+	input_page->input_vtl.as_uint8 = input_vtl.as_uint8;
+	input_page->rsvd_z8 = 0;
+	input_page->rsvd_z16 = 0;
+
+	while (remaining) {
+		rep_count = min(remaining, HV_GET_REGISTER_BATCH_SIZE);
+		for (i = 0; i < rep_count; ++i)
+			input_page->names[i] = registers[i].name;
+
+		status = hv_do_rep_hypercall(HVCALL_GET_VP_REGISTERS, rep_count,
+					     0, input_page, output_page);
+		if (!hv_result_success(status))
+			break;
+
+		completed = hv_repcomp(status);
+		for (i = 0; i < completed; ++i)
+			registers[i].value = output_page[i];
+
+		registers += completed;
+		remaining -= completed;
+	}
+	local_irq_restore(flags);
+
+	return hv_result_to_errno(status);
+}
+EXPORT_SYMBOL_GPL(hv_call_get_vp_registers);
+
+int hv_call_set_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+			     union hv_input_vtl input_vtl,
+			     struct hv_register_assoc *registers)
+{
+	struct hv_input_set_vp_registers *input_page;
+	u16 completed = 0;
+	unsigned long remaining = count;
+	int rep_count;
+	u64 status = HV_STATUS_SUCCESS;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	input_page->partition_id = partition_id;
+	input_page->vp_index = vp_index;
+	input_page->input_vtl.as_uint8 = input_vtl.as_uint8;
+	input_page->rsvd_z8 = 0;
+	input_page->rsvd_z16 = 0;
+
+	while (remaining) {
+		rep_count = min(remaining, HV_SET_REGISTER_BATCH_SIZE);
+		memcpy(input_page->elements, registers,
+		       sizeof(struct hv_register_assoc) * rep_count);
+
+		status = hv_do_rep_hypercall(HVCALL_SET_VP_REGISTERS, rep_count,
+					     0, input_page, NULL);
+		if (!hv_result_success(status))
+			break;
+
+		completed = hv_repcomp(status);
+		registers += completed;
+		remaining -= completed;
+	}
+
+	local_irq_restore(flags);
+
+	return hv_result_to_errno(status);
+}
+EXPORT_SYMBOL_GPL(hv_call_set_vp_registers);
+
+int hv_call_get_partition_property(u64 partition_id,
+				   u64 property_code,
+				   u64 *property_value)
+{
+	u64 status;
+	unsigned long flags;
+	struct hv_input_get_partition_property *input;
+	struct hv_output_get_partition_property *output;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+	memset(input, 0, sizeof(*input));
+	input->partition_id = partition_id;
+	input->property_code = property_code;
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_PROPERTY, input, output);
+
+	if (!hv_result_success(status)) {
+		local_irq_restore(flags);
+		return hv_result_to_errno(status);
+	}
+	*property_value = output->property_value;
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_call_get_partition_property);
+
+#ifdef CONFIG_X86
+/*
+ * Corresponding sleep states have to be initialized in order for a subsequent
+ * HVCALL_ENTER_SLEEP_STATE call to succeed. Currently only S5 state as per
+ * ACPI 6.4 chapter 7.4.2 is relevant, while S1, S2 and S3 can be supported.
+ *
+ * In order to pass proper PM values to mshv, ACPI should be initialized and
+ * should support S5 sleep state when this method is invoked.
+ */
+static int hv_initialize_sleep_states(void)
+{
+	u64 status;
+	unsigned long flags;
+	struct hv_input_set_system_property *in;
+	acpi_status acpi_status;
+	u8 sleep_type_a, sleep_type_b;
+
+	if (!acpi_sleep_state_supported(ACPI_STATE_S5)) {
+		pr_err("%s: S5 sleep state not supported.\n", __func__);
+		return -ENODEV;
+	}
+
+	acpi_status = acpi_get_sleep_type_data(ACPI_STATE_S5, &sleep_type_a,
+					       &sleep_type_b);
+	if (ACPI_FAILURE(acpi_status))
+		return -ENODEV;
+
+	local_irq_save(flags);
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(in, 0, sizeof(*in));
+
+	in->property_id = HV_SYSTEM_PROPERTY_SLEEP_STATE;
+	in->set_sleep_state_info.sleep_state = HV_SLEEP_STATE_S5;
+	in->set_sleep_state_info.pm1a_slp_typ = sleep_type_a;
+	in->set_sleep_state_info.pm1b_slp_typ = sleep_type_b;
+
+	status = hv_do_hypercall(HVCALL_SET_SYSTEM_PROPERTY, in, NULL);
+	local_irq_restore(flags);
+
+	if (!hv_result_success(status)) {
+		hv_status_err(status, "\n");
+		return hv_result_to_errno(status);
+	}
+
+	return 0;
+}
+
+/*
+ * This notifier initializes sleep states in mshv hypervisor which will be
+ * used during power off.
+ */
+static int hv_reboot_notifier_handler(struct notifier_block *this,
+				      unsigned long code, void *another)
+{
+	int ret = 0;
+
+	if (code == SYS_HALT || code == SYS_POWER_OFF)
+		ret = hv_initialize_sleep_states();
+
+	return ret ? NOTIFY_DONE : NOTIFY_OK;
+}
+
+static struct notifier_block hv_reboot_notifier = {
+	.notifier_call = hv_reboot_notifier_handler,
+};
+
+void hv_sleep_notifiers_register(void)
+{
+	int ret;
+
+	ret = register_reboot_notifier(&hv_reboot_notifier);
+	if (ret)
+		pr_err("%s: cannot register reboot notifier %d\n", __func__,
+		       ret);
+}
+
+/*
+ * Power off the machine by entering S5 sleep state via Hyper-V hypercall.
+ * This call does not return if successful.
+ */
+void hv_machine_power_off(void)
+{
+	unsigned long flags;
+	struct hv_input_enter_sleep_state *in;
+
+	local_irq_save(flags);
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	in->sleep_state = HV_SLEEP_STATE_S5;
+
+	(void)hv_do_hypercall(HVCALL_ENTER_SLEEP_STATE, in, NULL);
+	local_irq_restore(flags);
+
+	/* should never reach here */
+	BUG();
+
+}
+#endif
diff --git a/drivers/hv/mshv_debugfs.c b/drivers/hv/mshv_debugfs.c
new file mode 100644
index 000000000..3c3e02237
--- /dev/null
+++ b/drivers/hv/mshv_debugfs.c
@@ -0,0 +1,729 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2026, Microsoft Corporation.
+ *
+ * The /sys/kernel/debug/mshv directory contents.
+ * Contains various statistics data, provided by the hypervisor.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/debugfs.h>
+#include <linux/stringify.h>
+#include <asm/mshyperv.h>
+#include <linux/slab.h>
+
+#include "mshv.h"
+#include "mshv_root.h"
+
+/* Ensure this file is not used elsewhere by accident */
+#define MSHV_DEBUGFS_C
+#include "mshv_debugfs_counters.c"
+
+#define U32_BUF_SZ 11
+#define U64_BUF_SZ 21
+/* Only support SELF and PARENT areas */
+#define NUM_STATS_AREAS 2
+static_assert(HV_STATS_AREA_SELF == 0 && HV_STATS_AREA_PARENT == 1,
+	      "SELF and PARENT areas must be usable as indices into an array of size NUM_STATS_AREAS");
+/* HV_HYPERVISOR_COUNTER */
+#define HV_HYPERVISOR_COUNTER_LOGICAL_PROCESSORS 1
+
+static struct dentry *mshv_debugfs;
+static struct dentry *mshv_debugfs_partition;
+static struct dentry *mshv_debugfs_lp;
+static struct dentry **parent_vp_stats;
+static struct dentry *parent_partition_stats;
+
+static u64 mshv_lps_count;
+static struct hv_stats_page **mshv_lps_stats;
+
+static int lp_stats_show(struct seq_file *m, void *v)
+{
+	const struct hv_stats_page *stats = m->private;
+	int idx;
+
+	for (idx = 0; idx < ARRAY_SIZE(hv_lp_counters); idx++) {
+		char *name = hv_lp_counters[idx];
+
+		if (!name)
+			continue;
+		seq_printf(m, "%-32s: %llu\n", name, stats->data[idx]);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(lp_stats);
+
+static void mshv_lp_stats_unmap(u32 lp_index)
+{
+	union hv_stats_object_identity identity = {
+		.lp.lp_index = lp_index,
+		.lp.stats_area_type = HV_STATS_AREA_SELF,
+	};
+	int err;
+
+	err = hv_unmap_stats_page(HV_STATS_OBJECT_LOGICAL_PROCESSOR,
+				  mshv_lps_stats[lp_index], &identity);
+	if (err)
+		pr_err("%s: failed to unmap logical processor %u stats, err: %d\n",
+		       __func__, lp_index, err);
+
+	mshv_lps_stats[lp_index] = NULL;
+}
+
+static struct hv_stats_page * __init mshv_lp_stats_map(u32 lp_index)
+{
+	union hv_stats_object_identity identity = {
+		.lp.lp_index = lp_index,
+		.lp.stats_area_type = HV_STATS_AREA_SELF,
+	};
+	struct hv_stats_page *stats;
+	int err;
+
+	err = hv_map_stats_page(HV_STATS_OBJECT_LOGICAL_PROCESSOR, &identity,
+				&stats);
+	if (err) {
+		pr_err("%s: failed to map logical processor %u stats, err: %d\n",
+		       __func__, lp_index, err);
+		return ERR_PTR(err);
+	}
+	mshv_lps_stats[lp_index] = stats;
+
+	return stats;
+}
+
+static struct hv_stats_page * __init lp_debugfs_stats_create(u32 lp_index,
+							     struct dentry *parent)
+{
+	struct dentry *dentry;
+	struct hv_stats_page *stats;
+
+	stats = mshv_lp_stats_map(lp_index);
+	if (IS_ERR(stats))
+		return stats;
+
+	dentry = debugfs_create_file("stats", 0400, parent,
+				     stats, &lp_stats_fops);
+	if (IS_ERR(dentry)) {
+		mshv_lp_stats_unmap(lp_index);
+		return ERR_CAST(dentry);
+	}
+	return stats;
+}
+
+static int __init lp_debugfs_create(u32 lp_index, struct dentry *parent)
+{
+	struct dentry *idx;
+	char lp_idx_str[U32_BUF_SZ];
+	struct hv_stats_page *stats;
+	int err;
+
+	sprintf(lp_idx_str, "%u", lp_index);
+
+	idx = debugfs_create_dir(lp_idx_str, parent);
+	if (IS_ERR(idx))
+		return PTR_ERR(idx);
+
+	stats = lp_debugfs_stats_create(lp_index, idx);
+	if (IS_ERR(stats)) {
+		err = PTR_ERR(stats);
+		goto remove_debugfs_lp_idx;
+	}
+
+	return 0;
+
+remove_debugfs_lp_idx:
+	debugfs_remove_recursive(idx);
+	return err;
+}
+
+static void mshv_debugfs_lp_remove(void)
+{
+	int lp_index;
+
+	debugfs_remove_recursive(mshv_debugfs_lp);
+
+	for (lp_index = 0; lp_index < mshv_lps_count; lp_index++)
+		mshv_lp_stats_unmap(lp_index);
+
+	kfree(mshv_lps_stats);
+	mshv_lps_stats = NULL;
+}
+
+static int __init mshv_debugfs_lp_create(struct dentry *parent)
+{
+	struct dentry *lp_dir;
+	int err, lp_index;
+
+	mshv_lps_stats = kzalloc_objs(*mshv_lps_stats, mshv_lps_count,
+				      GFP_KERNEL_ACCOUNT);
+
+	if (!mshv_lps_stats)
+		return -ENOMEM;
+
+	lp_dir = debugfs_create_dir("lp", parent);
+	if (IS_ERR(lp_dir)) {
+		err = PTR_ERR(lp_dir);
+		goto free_lp_stats;
+	}
+
+	for (lp_index = 0; lp_index < mshv_lps_count; lp_index++) {
+		err = lp_debugfs_create(lp_index, lp_dir);
+		if (err)
+			goto remove_debugfs_lps;
+	}
+
+	mshv_debugfs_lp = lp_dir;
+
+	return 0;
+
+remove_debugfs_lps:
+	for (lp_index -= 1; lp_index >= 0; lp_index--)
+		mshv_lp_stats_unmap(lp_index);
+	debugfs_remove_recursive(lp_dir);
+free_lp_stats:
+	kfree(mshv_lps_stats);
+	mshv_lps_stats = NULL;
+
+	return err;
+}
+
+static int vp_stats_show(struct seq_file *m, void *v)
+{
+	const struct hv_stats_page **pstats = m->private;
+	u64 parent_val, self_val;
+	int idx;
+
+	/*
+	 * For VP and partition stats, there may be two stats areas mapped,
+	 * SELF and PARENT. These refer to the privilege level of the data in
+	 * each page. Some fields may be 0 in SELF and nonzero in PARENT, or
+	 * vice versa.
+	 *
+	 * Hence, prioritize printing from the PARENT page (more privileged
+	 * data), but use the value from the SELF page if the PARENT value is
+	 * 0.
+	 */
+
+	for (idx = 0; idx < ARRAY_SIZE(hv_vp_counters); idx++) {
+		char *name = hv_vp_counters[idx];
+
+		if (!name)
+			continue;
+
+		parent_val = pstats[HV_STATS_AREA_PARENT]->data[idx];
+		self_val = pstats[HV_STATS_AREA_SELF]->data[idx];
+		seq_printf(m, "%-43s: %llu\n", name,
+			   parent_val ? parent_val : self_val);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(vp_stats);
+
+static void vp_debugfs_remove(struct dentry *vp_stats)
+{
+	debugfs_remove_recursive(vp_stats->d_parent);
+}
+
+static int vp_debugfs_create(u64 partition_id, u32 vp_index,
+			     struct hv_stats_page **pstats,
+			     struct dentry **vp_stats_ptr,
+			     struct dentry *parent)
+{
+	struct dentry *vp_idx_dir, *d;
+	char vp_idx_str[U32_BUF_SZ];
+	int err;
+
+	sprintf(vp_idx_str, "%u", vp_index);
+
+	vp_idx_dir = debugfs_create_dir(vp_idx_str, parent);
+	if (IS_ERR(vp_idx_dir))
+		return PTR_ERR(vp_idx_dir);
+
+	d = debugfs_create_file("stats", 0400, vp_idx_dir,
+				pstats, &vp_stats_fops);
+	if (IS_ERR(d)) {
+		err = PTR_ERR(d);
+		goto remove_debugfs_vp_idx;
+	}
+
+	*vp_stats_ptr = d;
+
+	return 0;
+
+remove_debugfs_vp_idx:
+	debugfs_remove_recursive(vp_idx_dir);
+	return err;
+}
+
+static int partition_stats_show(struct seq_file *m, void *v)
+{
+	const struct hv_stats_page **pstats = m->private;
+	u64 parent_val, self_val;
+	int idx;
+
+	for (idx = 0; idx < ARRAY_SIZE(hv_partition_counters); idx++) {
+		char *name = hv_partition_counters[idx];
+
+		if (!name)
+			continue;
+
+		parent_val = pstats[HV_STATS_AREA_PARENT]->data[idx];
+		self_val = pstats[HV_STATS_AREA_SELF]->data[idx];
+		seq_printf(m, "%-37s: %llu\n", name,
+			   parent_val ? parent_val : self_val);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(partition_stats);
+
+static void mshv_partition_stats_unmap(u64 partition_id,
+				       struct hv_stats_page *stats_page,
+				       enum hv_stats_area_type stats_area_type)
+{
+	union hv_stats_object_identity identity = {
+		.partition.partition_id = partition_id,
+		.partition.stats_area_type = stats_area_type,
+	};
+	int err;
+
+	err = hv_unmap_stats_page(HV_STATS_OBJECT_PARTITION, stats_page,
+				  &identity);
+	if (err)
+		pr_err("%s: failed to unmap partition %lld %s stats, err: %d\n",
+		       __func__, partition_id,
+		       (stats_area_type == HV_STATS_AREA_SELF) ? "self" : "parent",
+		       err);
+}
+
+static struct hv_stats_page *mshv_partition_stats_map(u64 partition_id,
+						      enum hv_stats_area_type stats_area_type)
+{
+	union hv_stats_object_identity identity = {
+		.partition.partition_id = partition_id,
+		.partition.stats_area_type = stats_area_type,
+	};
+	struct hv_stats_page *stats;
+	int err;
+
+	err = hv_map_stats_page(HV_STATS_OBJECT_PARTITION, &identity, &stats);
+	if (err) {
+		pr_err("%s: failed to map partition %lld %s stats, err: %d\n",
+		       __func__, partition_id,
+		       (stats_area_type == HV_STATS_AREA_SELF) ? "self" : "parent",
+		       err);
+		return ERR_PTR(err);
+	}
+	return stats;
+}
+
+static int mshv_debugfs_partition_stats_create(u64 partition_id,
+					       struct dentry **partition_stats_ptr,
+					       struct dentry *parent)
+{
+	struct dentry *dentry;
+	struct hv_stats_page **pstats;
+	int err;
+
+	pstats = kzalloc_objs(struct hv_stats_page *, NUM_STATS_AREAS,
+			      GFP_KERNEL_ACCOUNT);
+	if (!pstats)
+		return -ENOMEM;
+
+	pstats[HV_STATS_AREA_SELF] = mshv_partition_stats_map(partition_id,
+							      HV_STATS_AREA_SELF);
+	if (IS_ERR(pstats[HV_STATS_AREA_SELF])) {
+		err = PTR_ERR(pstats[HV_STATS_AREA_SELF]);
+		goto cleanup;
+	}
+
+	/*
+	 * L1VH partition cannot access its partition stats in parent area.
+	 */
+	if (is_l1vh_parent(partition_id)) {
+		pstats[HV_STATS_AREA_PARENT] = pstats[HV_STATS_AREA_SELF];
+	} else {
+		pstats[HV_STATS_AREA_PARENT] = mshv_partition_stats_map(partition_id,
+									HV_STATS_AREA_PARENT);
+		if (IS_ERR(pstats[HV_STATS_AREA_PARENT])) {
+			err = PTR_ERR(pstats[HV_STATS_AREA_PARENT]);
+			goto unmap_self;
+		}
+		if (!pstats[HV_STATS_AREA_PARENT])
+			pstats[HV_STATS_AREA_PARENT] = pstats[HV_STATS_AREA_SELF];
+	}
+
+	dentry = debugfs_create_file("stats", 0400, parent,
+				     pstats, &partition_stats_fops);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto unmap_partition_stats;
+	}
+
+	*partition_stats_ptr = dentry;
+	return 0;
+
+unmap_partition_stats:
+	if (pstats[HV_STATS_AREA_PARENT] != pstats[HV_STATS_AREA_SELF])
+		mshv_partition_stats_unmap(partition_id, pstats[HV_STATS_AREA_PARENT],
+					   HV_STATS_AREA_PARENT);
+unmap_self:
+	mshv_partition_stats_unmap(partition_id, pstats[HV_STATS_AREA_SELF],
+				   HV_STATS_AREA_SELF);
+cleanup:
+	kfree(pstats);
+	return err;
+}
+
+static void partition_debugfs_remove(u64 partition_id, struct dentry *dentry)
+{
+	struct hv_stats_page **pstats = NULL;
+
+	pstats = dentry->d_inode->i_private;
+
+	debugfs_remove_recursive(dentry->d_parent);
+
+	if (pstats[HV_STATS_AREA_PARENT] != pstats[HV_STATS_AREA_SELF]) {
+		mshv_partition_stats_unmap(partition_id,
+					   pstats[HV_STATS_AREA_PARENT],
+					   HV_STATS_AREA_PARENT);
+	}
+
+	mshv_partition_stats_unmap(partition_id,
+				   pstats[HV_STATS_AREA_SELF],
+				   HV_STATS_AREA_SELF);
+
+	kfree(pstats);
+}
+
+static int partition_debugfs_create(u64 partition_id,
+				    struct dentry **vp_dir_ptr,
+				    struct dentry **partition_stats_ptr,
+				    struct dentry *parent)
+{
+	char part_id_str[U64_BUF_SZ];
+	struct dentry *part_id_dir, *vp_dir;
+	int err;
+
+	if (is_l1vh_parent(partition_id))
+		sprintf(part_id_str, "self");
+	else
+		sprintf(part_id_str, "%llu", partition_id);
+
+	part_id_dir = debugfs_create_dir(part_id_str, parent);
+	if (IS_ERR(part_id_dir))
+		return PTR_ERR(part_id_dir);
+
+	vp_dir = debugfs_create_dir("vp", part_id_dir);
+	if (IS_ERR(vp_dir)) {
+		err = PTR_ERR(vp_dir);
+		goto remove_debugfs_partition_id;
+	}
+
+	err = mshv_debugfs_partition_stats_create(partition_id,
+						  partition_stats_ptr,
+						  part_id_dir);
+	if (err)
+		goto remove_debugfs_partition_id;
+
+	*vp_dir_ptr = vp_dir;
+
+	return 0;
+
+remove_debugfs_partition_id:
+	debugfs_remove_recursive(part_id_dir);
+	return err;
+}
+
+static void parent_vp_debugfs_remove(u32 vp_index,
+				     struct dentry *vp_stats_ptr)
+{
+	struct hv_stats_page **pstats;
+
+	pstats = vp_stats_ptr->d_inode->i_private;
+	vp_debugfs_remove(vp_stats_ptr);
+	mshv_vp_stats_unmap(hv_current_partition_id, vp_index, pstats);
+	kfree(pstats);
+}
+
+static void mshv_debugfs_parent_partition_remove(void)
+{
+	int idx;
+
+	for_each_online_cpu(idx)
+		parent_vp_debugfs_remove(hv_vp_index[idx],
+					 parent_vp_stats[idx]);
+
+	partition_debugfs_remove(hv_current_partition_id,
+				 parent_partition_stats);
+	kfree(parent_vp_stats);
+	parent_vp_stats = NULL;
+	parent_partition_stats = NULL;
+}
+
+static int __init parent_vp_debugfs_create(u32 vp_index,
+					   struct dentry **vp_stats_ptr,
+					   struct dentry *parent)
+{
+	struct hv_stats_page **pstats;
+	int err;
+
+	pstats = kzalloc_objs(struct hv_stats_page *, NUM_STATS_AREAS,
+			      GFP_KERNEL_ACCOUNT);
+	if (!pstats)
+		return -ENOMEM;
+
+	err = mshv_vp_stats_map(hv_current_partition_id, vp_index, pstats);
+	if (err)
+		goto cleanup;
+
+	err = vp_debugfs_create(hv_current_partition_id, vp_index, pstats,
+				vp_stats_ptr, parent);
+	if (err)
+		goto unmap_vp_stats;
+
+	return 0;
+
+unmap_vp_stats:
+	mshv_vp_stats_unmap(hv_current_partition_id, vp_index, pstats);
+cleanup:
+	kfree(pstats);
+	return err;
+}
+
+static int __init mshv_debugfs_parent_partition_create(void)
+{
+	struct dentry *vp_dir;
+	int err, idx, i;
+
+	mshv_debugfs_partition = debugfs_create_dir("partition",
+						    mshv_debugfs);
+	if (IS_ERR(mshv_debugfs_partition))
+		return PTR_ERR(mshv_debugfs_partition);
+
+	err = partition_debugfs_create(hv_current_partition_id,
+				       &vp_dir,
+				       &parent_partition_stats,
+				       mshv_debugfs_partition);
+	if (err)
+		goto remove_debugfs_partition;
+
+	parent_vp_stats = kzalloc_objs(*parent_vp_stats, nr_cpu_ids);
+	if (!parent_vp_stats) {
+		err = -ENOMEM;
+		goto remove_debugfs_partition;
+	}
+
+	for_each_online_cpu(idx) {
+		err = parent_vp_debugfs_create(hv_vp_index[idx],
+					       &parent_vp_stats[idx],
+					       vp_dir);
+		if (err)
+			goto remove_debugfs_partition_vp;
+	}
+
+	return 0;
+
+remove_debugfs_partition_vp:
+	for_each_online_cpu(i) {
+		if (i >= idx)
+			break;
+		parent_vp_debugfs_remove(i, parent_vp_stats[i]);
+	}
+	partition_debugfs_remove(hv_current_partition_id,
+				 parent_partition_stats);
+
+	kfree(parent_vp_stats);
+	parent_vp_stats = NULL;
+	parent_partition_stats = NULL;
+
+remove_debugfs_partition:
+	debugfs_remove_recursive(mshv_debugfs_partition);
+	mshv_debugfs_partition = NULL;
+	return err;
+}
+
+static int hv_stats_show(struct seq_file *m, void *v)
+{
+	const struct hv_stats_page *stats = m->private;
+	int idx;
+
+	for (idx = 0; idx < ARRAY_SIZE(hv_hypervisor_counters); idx++) {
+		char *name = hv_hypervisor_counters[idx];
+
+		if (!name)
+			continue;
+		seq_printf(m, "%-27s: %llu\n", name, stats->data[idx]);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(hv_stats);
+
+static void mshv_hv_stats_unmap(void)
+{
+	union hv_stats_object_identity identity = {
+		.hv.stats_area_type = HV_STATS_AREA_SELF,
+	};
+	int err;
+
+	err = hv_unmap_stats_page(HV_STATS_OBJECT_HYPERVISOR, NULL, &identity);
+	if (err)
+		pr_err("%s: failed to unmap hypervisor stats: %d\n",
+		       __func__, err);
+}
+
+static void * __init mshv_hv_stats_map(void)
+{
+	union hv_stats_object_identity identity = {
+		.hv.stats_area_type = HV_STATS_AREA_SELF,
+	};
+	struct hv_stats_page *stats;
+	int err;
+
+	err = hv_map_stats_page(HV_STATS_OBJECT_HYPERVISOR, &identity, &stats);
+	if (err) {
+		pr_err("%s: failed to map hypervisor stats: %d\n",
+		       __func__, err);
+		return ERR_PTR(err);
+	}
+	return stats;
+}
+
+static int __init mshv_debugfs_hv_stats_create(struct dentry *parent)
+{
+	struct dentry *dentry;
+	u64 *stats;
+	int err;
+
+	stats = mshv_hv_stats_map();
+	if (IS_ERR(stats))
+		return PTR_ERR(stats);
+
+	dentry = debugfs_create_file("stats", 0400, parent,
+				     stats, &hv_stats_fops);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		pr_err("%s: failed to create hypervisor stats dentry: %d\n",
+		       __func__, err);
+		goto unmap_hv_stats;
+	}
+
+	mshv_lps_count = stats[HV_HYPERVISOR_COUNTER_LOGICAL_PROCESSORS];
+
+	return 0;
+
+unmap_hv_stats:
+	mshv_hv_stats_unmap();
+	return err;
+}
+
+int mshv_debugfs_vp_create(struct mshv_vp *vp)
+{
+	struct mshv_partition *p = vp->vp_partition;
+
+	if (!mshv_debugfs)
+		return 0;
+
+	return vp_debugfs_create(p->pt_id, vp->vp_index,
+				 vp->vp_stats_pages,
+				 &vp->vp_stats_dentry,
+				 p->pt_vp_dentry);
+}
+
+void mshv_debugfs_vp_remove(struct mshv_vp *vp)
+{
+	if (!mshv_debugfs)
+		return;
+
+	vp_debugfs_remove(vp->vp_stats_dentry);
+}
+
+int mshv_debugfs_partition_create(struct mshv_partition *partition)
+{
+	int err;
+
+	if (!mshv_debugfs)
+		return 0;
+
+	err = partition_debugfs_create(partition->pt_id,
+				       &partition->pt_vp_dentry,
+				       &partition->pt_stats_dentry,
+				       mshv_debugfs_partition);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+void mshv_debugfs_partition_remove(struct mshv_partition *partition)
+{
+	if (!mshv_debugfs)
+		return;
+
+	partition_debugfs_remove(partition->pt_id,
+				 partition->pt_stats_dentry);
+}
+
+int __init mshv_debugfs_init(void)
+{
+	int err;
+
+	mshv_debugfs = debugfs_create_dir("mshv", NULL);
+	if (IS_ERR(mshv_debugfs)) {
+		err = PTR_ERR(mshv_debugfs);
+		mshv_debugfs = NULL;
+		pr_err("%s: failed to create debugfs directory\n", __func__);
+		return err;
+	}
+
+	if (hv_root_partition()) {
+		err = mshv_debugfs_hv_stats_create(mshv_debugfs);
+		if (err)
+			goto remove_mshv_dir;
+
+		err = mshv_debugfs_lp_create(mshv_debugfs);
+		if (err)
+			goto unmap_hv_stats;
+	}
+
+	err = mshv_debugfs_parent_partition_create();
+	if (err)
+		goto unmap_lp_stats;
+
+	return 0;
+
+unmap_lp_stats:
+	if (hv_root_partition()) {
+		mshv_debugfs_lp_remove();
+		mshv_debugfs_lp = NULL;
+	}
+unmap_hv_stats:
+	if (hv_root_partition())
+		mshv_hv_stats_unmap();
+remove_mshv_dir:
+	debugfs_remove_recursive(mshv_debugfs);
+	mshv_debugfs = NULL;
+	return err;
+}
+
+void mshv_debugfs_exit(void)
+{
+	if (!mshv_debugfs)
+		return;
+
+	mshv_debugfs_parent_partition_remove();
+
+	if (hv_root_partition()) {
+		mshv_debugfs_lp_remove();
+		mshv_debugfs_lp = NULL;
+		mshv_hv_stats_unmap();
+	}
+
+	debugfs_remove_recursive(mshv_debugfs);
+	mshv_debugfs = NULL;
+	mshv_debugfs_partition = NULL;
+}
diff --git a/drivers/hv/mshv_debugfs_counters.c b/drivers/hv/mshv_debugfs_counters.c
new file mode 100644
index 000000000..978536ba6
--- /dev/null
+++ b/drivers/hv/mshv_debugfs_counters.c
@@ -0,0 +1,490 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2026, Microsoft Corporation.
+ *
+ * Data for printing stats page counters via debugfs.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+/*
+ * For simplicity, this file is included directly in mshv_debugfs.c.
+ * If these are ever needed elsewhere they should be compiled separately.
+ * Ensure this file is not used twice by accident.
+ */
+#ifndef MSHV_DEBUGFS_C
+#error "This file should only be included in mshv_debugfs.c"
+#endif
+
+/* HV_HYPERVISOR_COUNTER */
+static char *hv_hypervisor_counters[] = {
+	[1] = "HvLogicalProcessors",
+	[2] = "HvPartitions",
+	[3] = "HvTotalPages",
+	[4] = "HvVirtualProcessors",
+	[5] = "HvMonitoredNotifications",
+	[6] = "HvModernStandbyEntries",
+	[7] = "HvPlatformIdleTransitions",
+	[8] = "HvHypervisorStartupCost",
+
+	[10] = "HvIOSpacePages",
+	[11] = "HvNonEssentialPagesForDump",
+	[12] = "HvSubsumedPages",
+};
+
+/* HV_CPU_COUNTER */
+static char *hv_lp_counters[] = {
+	[1] = "LpGlobalTime",
+	[2] = "LpTotalRunTime",
+	[3] = "LpHypervisorRunTime",
+	[4] = "LpHardwareInterrupts",
+	[5] = "LpContextSwitches",
+	[6] = "LpInterProcessorInterrupts",
+	[7] = "LpSchedulerInterrupts",
+	[8] = "LpTimerInterrupts",
+	[9] = "LpInterProcessorInterruptsSent",
+	[10] = "LpProcessorHalts",
+	[11] = "LpMonitorTransitionCost",
+	[12] = "LpContextSwitchTime",
+	[13] = "LpC1TransitionsCount",
+	[14] = "LpC1RunTime",
+	[15] = "LpC2TransitionsCount",
+	[16] = "LpC2RunTime",
+	[17] = "LpC3TransitionsCount",
+	[18] = "LpC3RunTime",
+	[19] = "LpRootVpIndex",
+	[20] = "LpIdleSequenceNumber",
+	[21] = "LpGlobalTscCount",
+	[22] = "LpActiveTscCount",
+	[23] = "LpIdleAccumulation",
+	[24] = "LpReferenceCycleCount0",
+	[25] = "LpActualCycleCount0",
+	[26] = "LpReferenceCycleCount1",
+	[27] = "LpActualCycleCount1",
+	[28] = "LpProximityDomainId",
+	[29] = "LpPostedInterruptNotifications",
+	[30] = "LpBranchPredictorFlushes",
+#if IS_ENABLED(CONFIG_X86_64)
+	[31] = "LpL1DataCacheFlushes",
+	[32] = "LpImmediateL1DataCacheFlushes",
+	[33] = "LpMbFlushes",
+	[34] = "LpCounterRefreshSequenceNumber",
+	[35] = "LpCounterRefreshReferenceTime",
+	[36] = "LpIdleAccumulationSnapshot",
+	[37] = "LpActiveTscCountSnapshot",
+	[38] = "LpHwpRequestContextSwitches",
+	[39] = "LpPlaceholder1",
+	[40] = "LpPlaceholder2",
+	[41] = "LpPlaceholder3",
+	[42] = "LpPlaceholder4",
+	[43] = "LpPlaceholder5",
+	[44] = "LpPlaceholder6",
+	[45] = "LpPlaceholder7",
+	[46] = "LpPlaceholder8",
+	[47] = "LpPlaceholder9",
+	[48] = "LpSchLocalRunListSize",
+	[49] = "LpReserveGroupId",
+	[50] = "LpRunningPriority",
+	[51] = "LpPerfmonInterruptCount",
+#elif IS_ENABLED(CONFIG_ARM64)
+	[31] = "LpCounterRefreshSequenceNumber",
+	[32] = "LpCounterRefreshReferenceTime",
+	[33] = "LpIdleAccumulationSnapshot",
+	[34] = "LpActiveTscCountSnapshot",
+	[35] = "LpHwpRequestContextSwitches",
+	[36] = "LpPlaceholder2",
+	[37] = "LpPlaceholder3",
+	[38] = "LpPlaceholder4",
+	[39] = "LpPlaceholder5",
+	[40] = "LpPlaceholder6",
+	[41] = "LpPlaceholder7",
+	[42] = "LpPlaceholder8",
+	[43] = "LpPlaceholder9",
+	[44] = "LpSchLocalRunListSize",
+	[45] = "LpReserveGroupId",
+	[46] = "LpRunningPriority",
+#endif
+};
+
+/* HV_PROCESS_COUNTER */
+static char *hv_partition_counters[] = {
+	[1] = "PtVirtualProcessors",
+
+	[3] = "PtTlbSize",
+	[4] = "PtAddressSpaces",
+	[5] = "PtDepositedPages",
+	[6] = "PtGpaPages",
+	[7] = "PtGpaSpaceModifications",
+	[8] = "PtVirtualTlbFlushEntires",
+	[9] = "PtRecommendedTlbSize",
+	[10] = "PtGpaPages4K",
+	[11] = "PtGpaPages2M",
+	[12] = "PtGpaPages1G",
+	[13] = "PtGpaPages512G",
+	[14] = "PtDevicePages4K",
+	[15] = "PtDevicePages2M",
+	[16] = "PtDevicePages1G",
+	[17] = "PtDevicePages512G",
+	[18] = "PtAttachedDevices",
+	[19] = "PtDeviceInterruptMappings",
+	[20] = "PtIoTlbFlushes",
+	[21] = "PtIoTlbFlushCost",
+	[22] = "PtDeviceInterruptErrors",
+	[23] = "PtDeviceDmaErrors",
+	[24] = "PtDeviceInterruptThrottleEvents",
+	[25] = "PtSkippedTimerTicks",
+	[26] = "PtPartitionId",
+#if IS_ENABLED(CONFIG_X86_64)
+	[27] = "PtNestedTlbSize",
+	[28] = "PtRecommendedNestedTlbSize",
+	[29] = "PtNestedTlbFreeListSize",
+	[30] = "PtNestedTlbTrimmedPages",
+	[31] = "PtPagesShattered",
+	[32] = "PtPagesRecombined",
+	[33] = "PtHwpRequestValue",
+	[34] = "PtAutoSuspendEnableTime",
+	[35] = "PtAutoSuspendTriggerTime",
+	[36] = "PtAutoSuspendDisableTime",
+	[37] = "PtPlaceholder1",
+	[38] = "PtPlaceholder2",
+	[39] = "PtPlaceholder3",
+	[40] = "PtPlaceholder4",
+	[41] = "PtPlaceholder5",
+	[42] = "PtPlaceholder6",
+	[43] = "PtPlaceholder7",
+	[44] = "PtPlaceholder8",
+	[45] = "PtHypervisorStateTransferGeneration",
+	[46] = "PtNumberofActiveChildPartitions",
+#elif IS_ENABLED(CONFIG_ARM64)
+	[27] = "PtHwpRequestValue",
+	[28] = "PtAutoSuspendEnableTime",
+	[29] = "PtAutoSuspendTriggerTime",
+	[30] = "PtAutoSuspendDisableTime",
+	[31] = "PtPlaceholder1",
+	[32] = "PtPlaceholder2",
+	[33] = "PtPlaceholder3",
+	[34] = "PtPlaceholder4",
+	[35] = "PtPlaceholder5",
+	[36] = "PtPlaceholder6",
+	[37] = "PtPlaceholder7",
+	[38] = "PtPlaceholder8",
+	[39] = "PtHypervisorStateTransferGeneration",
+	[40] = "PtNumberofActiveChildPartitions",
+#endif
+};
+
+/* HV_THREAD_COUNTER */
+static char *hv_vp_counters[] = {
+	[1] = "VpTotalRunTime",
+	[2] = "VpHypervisorRunTime",
+	[3] = "VpRemoteNodeRunTime",
+	[4] = "VpNormalizedRunTime",
+	[5] = "VpIdealCpu",
+
+	[7] = "VpHypercallsCount",
+	[8] = "VpHypercallsTime",
+#if IS_ENABLED(CONFIG_X86_64)
+	[9] = "VpPageInvalidationsCount",
+	[10] = "VpPageInvalidationsTime",
+	[11] = "VpControlRegisterAccessesCount",
+	[12] = "VpControlRegisterAccessesTime",
+	[13] = "VpIoInstructionsCount",
+	[14] = "VpIoInstructionsTime",
+	[15] = "VpHltInstructionsCount",
+	[16] = "VpHltInstructionsTime",
+	[17] = "VpMwaitInstructionsCount",
+	[18] = "VpMwaitInstructionsTime",
+	[19] = "VpCpuidInstructionsCount",
+	[20] = "VpCpuidInstructionsTime",
+	[21] = "VpMsrAccessesCount",
+	[22] = "VpMsrAccessesTime",
+	[23] = "VpOtherInterceptsCount",
+	[24] = "VpOtherInterceptsTime",
+	[25] = "VpExternalInterruptsCount",
+	[26] = "VpExternalInterruptsTime",
+	[27] = "VpPendingInterruptsCount",
+	[28] = "VpPendingInterruptsTime",
+	[29] = "VpEmulatedInstructionsCount",
+	[30] = "VpEmulatedInstructionsTime",
+	[31] = "VpDebugRegisterAccessesCount",
+	[32] = "VpDebugRegisterAccessesTime",
+	[33] = "VpPageFaultInterceptsCount",
+	[34] = "VpPageFaultInterceptsTime",
+	[35] = "VpGuestPageTableMaps",
+	[36] = "VpLargePageTlbFills",
+	[37] = "VpSmallPageTlbFills",
+	[38] = "VpReflectedGuestPageFaults",
+	[39] = "VpApicMmioAccesses",
+	[40] = "VpIoInterceptMessages",
+	[41] = "VpMemoryInterceptMessages",
+	[42] = "VpApicEoiAccesses",
+	[43] = "VpOtherMessages",
+	[44] = "VpPageTableAllocations",
+	[45] = "VpLogicalProcessorMigrations",
+	[46] = "VpAddressSpaceEvictions",
+	[47] = "VpAddressSpaceSwitches",
+	[48] = "VpAddressDomainFlushes",
+	[49] = "VpAddressSpaceFlushes",
+	[50] = "VpGlobalGvaRangeFlushes",
+	[51] = "VpLocalGvaRangeFlushes",
+	[52] = "VpPageTableEvictions",
+	[53] = "VpPageTableReclamations",
+	[54] = "VpPageTableResets",
+	[55] = "VpPageTableValidations",
+	[56] = "VpApicTprAccesses",
+	[57] = "VpPageTableWriteIntercepts",
+	[58] = "VpSyntheticInterrupts",
+	[59] = "VpVirtualInterrupts",
+	[60] = "VpApicIpisSent",
+	[61] = "VpApicSelfIpisSent",
+	[62] = "VpGpaSpaceHypercalls",
+	[63] = "VpLogicalProcessorHypercalls",
+	[64] = "VpLongSpinWaitHypercalls",
+	[65] = "VpOtherHypercalls",
+	[66] = "VpSyntheticInterruptHypercalls",
+	[67] = "VpVirtualInterruptHypercalls",
+	[68] = "VpVirtualMmuHypercalls",
+	[69] = "VpVirtualProcessorHypercalls",
+	[70] = "VpHardwareInterrupts",
+	[71] = "VpNestedPageFaultInterceptsCount",
+	[72] = "VpNestedPageFaultInterceptsTime",
+	[73] = "VpPageScans",
+	[74] = "VpLogicalProcessorDispatches",
+	[75] = "VpWaitingForCpuTime",
+	[76] = "VpExtendedHypercalls",
+	[77] = "VpExtendedHypercallInterceptMessages",
+	[78] = "VpMbecNestedPageTableSwitches",
+	[79] = "VpOtherReflectedGuestExceptions",
+	[80] = "VpGlobalIoTlbFlushes",
+	[81] = "VpGlobalIoTlbFlushCost",
+	[82] = "VpLocalIoTlbFlushes",
+	[83] = "VpLocalIoTlbFlushCost",
+	[84] = "VpHypercallsForwardedCount",
+	[85] = "VpHypercallsForwardingTime",
+	[86] = "VpPageInvalidationsForwardedCount",
+	[87] = "VpPageInvalidationsForwardingTime",
+	[88] = "VpControlRegisterAccessesForwardedCount",
+	[89] = "VpControlRegisterAccessesForwardingTime",
+	[90] = "VpIoInstructionsForwardedCount",
+	[91] = "VpIoInstructionsForwardingTime",
+	[92] = "VpHltInstructionsForwardedCount",
+	[93] = "VpHltInstructionsForwardingTime",
+	[94] = "VpMwaitInstructionsForwardedCount",
+	[95] = "VpMwaitInstructionsForwardingTime",
+	[96] = "VpCpuidInstructionsForwardedCount",
+	[97] = "VpCpuidInstructionsForwardingTime",
+	[98] = "VpMsrAccessesForwardedCount",
+	[99] = "VpMsrAccessesForwardingTime",
+	[100] = "VpOtherInterceptsForwardedCount",
+	[101] = "VpOtherInterceptsForwardingTime",
+	[102] = "VpExternalInterruptsForwardedCount",
+	[103] = "VpExternalInterruptsForwardingTime",
+	[104] = "VpPendingInterruptsForwardedCount",
+	[105] = "VpPendingInterruptsForwardingTime",
+	[106] = "VpEmulatedInstructionsForwardedCount",
+	[107] = "VpEmulatedInstructionsForwardingTime",
+	[108] = "VpDebugRegisterAccessesForwardedCount",
+	[109] = "VpDebugRegisterAccessesForwardingTime",
+	[110] = "VpPageFaultInterceptsForwardedCount",
+	[111] = "VpPageFaultInterceptsForwardingTime",
+	[112] = "VpVmclearEmulationCount",
+	[113] = "VpVmclearEmulationTime",
+	[114] = "VpVmptrldEmulationCount",
+	[115] = "VpVmptrldEmulationTime",
+	[116] = "VpVmptrstEmulationCount",
+	[117] = "VpVmptrstEmulationTime",
+	[118] = "VpVmreadEmulationCount",
+	[119] = "VpVmreadEmulationTime",
+	[120] = "VpVmwriteEmulationCount",
+	[121] = "VpVmwriteEmulationTime",
+	[122] = "VpVmxoffEmulationCount",
+	[123] = "VpVmxoffEmulationTime",
+	[124] = "VpVmxonEmulationCount",
+	[125] = "VpVmxonEmulationTime",
+	[126] = "VpNestedVMEntriesCount",
+	[127] = "VpNestedVMEntriesTime",
+	[128] = "VpNestedSLATSoftPageFaultsCount",
+	[129] = "VpNestedSLATSoftPageFaultsTime",
+	[130] = "VpNestedSLATHardPageFaultsCount",
+	[131] = "VpNestedSLATHardPageFaultsTime",
+	[132] = "VpInvEptAllContextEmulationCount",
+	[133] = "VpInvEptAllContextEmulationTime",
+	[134] = "VpInvEptSingleContextEmulationCount",
+	[135] = "VpInvEptSingleContextEmulationTime",
+	[136] = "VpInvVpidAllContextEmulationCount",
+	[137] = "VpInvVpidAllContextEmulationTime",
+	[138] = "VpInvVpidSingleContextEmulationCount",
+	[139] = "VpInvVpidSingleContextEmulationTime",
+	[140] = "VpInvVpidSingleAddressEmulationCount",
+	[141] = "VpInvVpidSingleAddressEmulationTime",
+	[142] = "VpNestedTlbPageTableReclamations",
+	[143] = "VpNestedTlbPageTableEvictions",
+	[144] = "VpFlushGuestPhysicalAddressSpaceHypercalls",
+	[145] = "VpFlushGuestPhysicalAddressListHypercalls",
+	[146] = "VpPostedInterruptNotifications",
+	[147] = "VpPostedInterruptScans",
+	[148] = "VpTotalCoreRunTime",
+	[149] = "VpMaximumRunTime",
+	[150] = "VpHwpRequestContextSwitches",
+	[151] = "VpWaitingForCpuTimeBucket0",
+	[152] = "VpWaitingForCpuTimeBucket1",
+	[153] = "VpWaitingForCpuTimeBucket2",
+	[154] = "VpWaitingForCpuTimeBucket3",
+	[155] = "VpWaitingForCpuTimeBucket4",
+	[156] = "VpWaitingForCpuTimeBucket5",
+	[157] = "VpWaitingForCpuTimeBucket6",
+	[158] = "VpVmloadEmulationCount",
+	[159] = "VpVmloadEmulationTime",
+	[160] = "VpVmsaveEmulationCount",
+	[161] = "VpVmsaveEmulationTime",
+	[162] = "VpGifInstructionEmulationCount",
+	[163] = "VpGifInstructionEmulationTime",
+	[164] = "VpEmulatedErrataSvmInstructions",
+	[165] = "VpPlaceholder1",
+	[166] = "VpPlaceholder2",
+	[167] = "VpPlaceholder3",
+	[168] = "VpPlaceholder4",
+	[169] = "VpPlaceholder5",
+	[170] = "VpPlaceholder6",
+	[171] = "VpPlaceholder7",
+	[172] = "VpPlaceholder8",
+	[173] = "VpContentionTime",
+	[174] = "VpWakeUpTime",
+	[175] = "VpSchedulingPriority",
+	[176] = "VpRdpmcInstructionsCount",
+	[177] = "VpRdpmcInstructionsTime",
+	[178] = "VpPerfmonPmuMsrAccessesCount",
+	[179] = "VpPerfmonLbrMsrAccessesCount",
+	[180] = "VpPerfmonIptMsrAccessesCount",
+	[181] = "VpPerfmonInterruptCount",
+	[182] = "VpVtl1DispatchCount",
+	[183] = "VpVtl2DispatchCount",
+	[184] = "VpVtl2DispatchBucket0",
+	[185] = "VpVtl2DispatchBucket1",
+	[186] = "VpVtl2DispatchBucket2",
+	[187] = "VpVtl2DispatchBucket3",
+	[188] = "VpVtl2DispatchBucket4",
+	[189] = "VpVtl2DispatchBucket5",
+	[190] = "VpVtl2DispatchBucket6",
+	[191] = "VpVtl1RunTime",
+	[192] = "VpVtl2RunTime",
+	[193] = "VpIommuHypercalls",
+	[194] = "VpCpuGroupHypercalls",
+	[195] = "VpVsmHypercalls",
+	[196] = "VpEventLogHypercalls",
+	[197] = "VpDeviceDomainHypercalls",
+	[198] = "VpDepositHypercalls",
+	[199] = "VpSvmHypercalls",
+	[200] = "VpBusLockAcquisitionCount",
+	[201] = "VpLoadAvg",
+	[202] = "VpRootDispatchThreadBlocked",
+	[203] = "VpIdleCpuTime",
+	[204] = "VpWaitingForCpuTimeBucket7",
+	[205] = "VpWaitingForCpuTimeBucket8",
+	[206] = "VpWaitingForCpuTimeBucket9",
+	[207] = "VpWaitingForCpuTimeBucket10",
+	[208] = "VpWaitingForCpuTimeBucket11",
+	[209] = "VpWaitingForCpuTimeBucket12",
+	[210] = "VpHierarchicalSuspendTime",
+	[211] = "VpExpressSchedulingAttempts",
+	[212] = "VpExpressSchedulingCount",
+#elif IS_ENABLED(CONFIG_ARM64)
+	[9] = "VpSysRegAccessesCount",
+	[10] = "VpSysRegAccessesTime",
+	[11] = "VpSmcInstructionsCount",
+	[12] = "VpSmcInstructionsTime",
+	[13] = "VpOtherInterceptsCount",
+	[14] = "VpOtherInterceptsTime",
+	[15] = "VpExternalInterruptsCount",
+	[16] = "VpExternalInterruptsTime",
+	[17] = "VpPendingInterruptsCount",
+	[18] = "VpPendingInterruptsTime",
+	[19] = "VpGuestPageTableMaps",
+	[20] = "VpLargePageTlbFills",
+	[21] = "VpSmallPageTlbFills",
+	[22] = "VpReflectedGuestPageFaults",
+	[23] = "VpMemoryInterceptMessages",
+	[24] = "VpOtherMessages",
+	[25] = "VpLogicalProcessorMigrations",
+	[26] = "VpAddressDomainFlushes",
+	[27] = "VpAddressSpaceFlushes",
+	[28] = "VpSyntheticInterrupts",
+	[29] = "VpVirtualInterrupts",
+	[30] = "VpApicSelfIpisSent",
+	[31] = "VpGpaSpaceHypercalls",
+	[32] = "VpLogicalProcessorHypercalls",
+	[33] = "VpLongSpinWaitHypercalls",
+	[34] = "VpOtherHypercalls",
+	[35] = "VpSyntheticInterruptHypercalls",
+	[36] = "VpVirtualInterruptHypercalls",
+	[37] = "VpVirtualMmuHypercalls",
+	[38] = "VpVirtualProcessorHypercalls",
+	[39] = "VpHardwareInterrupts",
+	[40] = "VpNestedPageFaultInterceptsCount",
+	[41] = "VpNestedPageFaultInterceptsTime",
+	[42] = "VpLogicalProcessorDispatches",
+	[43] = "VpWaitingForCpuTime",
+	[44] = "VpExtendedHypercalls",
+	[45] = "VpExtendedHypercallInterceptMessages",
+	[46] = "VpMbecNestedPageTableSwitches",
+	[47] = "VpOtherReflectedGuestExceptions",
+	[48] = "VpGlobalIoTlbFlushes",
+	[49] = "VpGlobalIoTlbFlushCost",
+	[50] = "VpLocalIoTlbFlushes",
+	[51] = "VpLocalIoTlbFlushCost",
+	[52] = "VpFlushGuestPhysicalAddressSpaceHypercalls",
+	[53] = "VpFlushGuestPhysicalAddressListHypercalls",
+	[54] = "VpPostedInterruptNotifications",
+	[55] = "VpPostedInterruptScans",
+	[56] = "VpTotalCoreRunTime",
+	[57] = "VpMaximumRunTime",
+	[58] = "VpWaitingForCpuTimeBucket0",
+	[59] = "VpWaitingForCpuTimeBucket1",
+	[60] = "VpWaitingForCpuTimeBucket2",
+	[61] = "VpWaitingForCpuTimeBucket3",
+	[62] = "VpWaitingForCpuTimeBucket4",
+	[63] = "VpWaitingForCpuTimeBucket5",
+	[64] = "VpWaitingForCpuTimeBucket6",
+	[65] = "VpHwpRequestContextSwitches",
+	[66] = "VpPlaceholder2",
+	[67] = "VpPlaceholder3",
+	[68] = "VpPlaceholder4",
+	[69] = "VpPlaceholder5",
+	[70] = "VpPlaceholder6",
+	[71] = "VpPlaceholder7",
+	[72] = "VpPlaceholder8",
+	[73] = "VpContentionTime",
+	[74] = "VpWakeUpTime",
+	[75] = "VpSchedulingPriority",
+	[76] = "VpVtl1DispatchCount",
+	[77] = "VpVtl2DispatchCount",
+	[78] = "VpVtl2DispatchBucket0",
+	[79] = "VpVtl2DispatchBucket1",
+	[80] = "VpVtl2DispatchBucket2",
+	[81] = "VpVtl2DispatchBucket3",
+	[82] = "VpVtl2DispatchBucket4",
+	[83] = "VpVtl2DispatchBucket5",
+	[84] = "VpVtl2DispatchBucket6",
+	[85] = "VpVtl1RunTime",
+	[86] = "VpVtl2RunTime",
+	[87] = "VpIommuHypercalls",
+	[88] = "VpCpuGroupHypercalls",
+	[89] = "VpVsmHypercalls",
+	[90] = "VpEventLogHypercalls",
+	[91] = "VpDeviceDomainHypercalls",
+	[92] = "VpDepositHypercalls",
+	[93] = "VpSvmHypercalls",
+	[94] = "VpLoadAvg",
+	[95] = "VpRootDispatchThreadBlocked",
+	[96] = "VpIdleCpuTime",
+	[97] = "VpWaitingForCpuTimeBucket7",
+	[98] = "VpWaitingForCpuTimeBucket8",
+	[99] = "VpWaitingForCpuTimeBucket9",
+	[100] = "VpWaitingForCpuTimeBucket10",
+	[101] = "VpWaitingForCpuTimeBucket11",
+	[102] = "VpWaitingForCpuTimeBucket12",
+	[103] = "VpHierarchicalSuspendTime",
+	[104] = "VpExpressSchedulingAttempts",
+	[105] = "VpExpressSchedulingCount",
+#endif
+};
diff --git a/drivers/hv/mshv_eventfd.c b/drivers/hv/mshv_eventfd.c
new file mode 100644
index 000000000..06aef99c8
--- /dev/null
+++ b/drivers/hv/mshv_eventfd.c
@@ -0,0 +1,864 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * eventfd support for mshv
+ *
+ * Heavily inspired from KVM implementation of irqfd/ioeventfd. The basic
+ * framework code is taken from the kvm implementation.
+ *
+ * All credits to kvm developers.
+ */
+
+#include <linux/syscalls.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/list.h>
+#include <linux/workqueue.h>
+#include <linux/eventfd.h>
+
+#if IS_ENABLED(CONFIG_X86_64)
+#include <asm/apic.h>
+#endif
+#include <asm/mshyperv.h>
+
+#include "mshv_eventfd.h"
+#include "mshv.h"
+#include "mshv_root.h"
+
+static struct workqueue_struct *irqfd_cleanup_wq;
+
+void mshv_register_irq_ack_notifier(struct mshv_partition *partition,
+				    struct mshv_irq_ack_notifier *mian)
+{
+	mutex_lock(&partition->pt_irq_lock);
+	hlist_add_head_rcu(&mian->link, &partition->irq_ack_notifier_list);
+	mutex_unlock(&partition->pt_irq_lock);
+}
+
+void mshv_unregister_irq_ack_notifier(struct mshv_partition *partition,
+				      struct mshv_irq_ack_notifier *mian)
+{
+	mutex_lock(&partition->pt_irq_lock);
+	hlist_del_init_rcu(&mian->link);
+	mutex_unlock(&partition->pt_irq_lock);
+	synchronize_rcu();
+}
+
+bool mshv_notify_acked_gsi(struct mshv_partition *partition, int gsi)
+{
+	struct mshv_irq_ack_notifier *mian;
+	bool acked = false;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(mian, &partition->irq_ack_notifier_list,
+				 link) {
+		if (mian->irq_ack_gsi == gsi) {
+			mian->irq_acked(mian);
+			acked = true;
+		}
+	}
+	rcu_read_unlock();
+
+	return acked;
+}
+
+#if IS_ENABLED(CONFIG_ARM64)
+static inline bool hv_should_clear_interrupt(enum hv_interrupt_type type)
+{
+	return false;
+}
+#elif IS_ENABLED(CONFIG_X86_64)
+static inline bool hv_should_clear_interrupt(enum hv_interrupt_type type)
+{
+	return type == HV_X64_INTERRUPT_TYPE_EXTINT;
+}
+#endif
+
+static void mshv_irqfd_resampler_ack(struct mshv_irq_ack_notifier *mian)
+{
+	struct mshv_irqfd_resampler *resampler;
+	struct mshv_partition *partition;
+	struct mshv_irqfd *irqfd;
+	int idx;
+
+	resampler = container_of(mian, struct mshv_irqfd_resampler,
+				 rsmplr_notifier);
+	partition = resampler->rsmplr_partn;
+
+	idx = srcu_read_lock(&partition->pt_irq_srcu);
+
+	hlist_for_each_entry_srcu(irqfd, &resampler->rsmplr_irqfd_list,
+				 irqfd_resampler_hnode,
+				 srcu_read_lock_held(&partition->pt_irq_srcu)) {
+		if (hv_should_clear_interrupt(irqfd->irqfd_lapic_irq.lapic_control.interrupt_type))
+			hv_call_clear_virtual_interrupt(partition->pt_id);
+
+		eventfd_signal(irqfd->irqfd_resamplefd);
+	}
+
+	srcu_read_unlock(&partition->pt_irq_srcu, idx);
+}
+
+#if IS_ENABLED(CONFIG_X86_64)
+static bool
+mshv_vp_irq_vector_injected(union hv_vp_register_page_interrupt_vectors iv,
+			    u32 vector)
+{
+	int i;
+
+	for (i = 0; i < iv.vector_count; i++) {
+		if (iv.vector[i] == vector)
+			return true;
+	}
+
+	return false;
+}
+
+static int mshv_vp_irq_try_set_vector(struct mshv_vp *vp, u32 vector)
+{
+	union hv_vp_register_page_interrupt_vectors iv, new_iv;
+
+	iv = vp->vp_register_page->interrupt_vectors;
+	new_iv = iv;
+
+	if (mshv_vp_irq_vector_injected(iv, vector))
+		return 0;
+
+	if (iv.vector_count >= HV_VP_REGISTER_PAGE_MAX_VECTOR_COUNT)
+		return -ENOSPC;
+
+	new_iv.vector[new_iv.vector_count++] = vector;
+
+	if (!try_cmpxchg(&vp->vp_register_page->interrupt_vectors.as_uint64,
+			 &iv.as_uint64, new_iv.as_uint64))
+		return -EAGAIN;
+
+	return 0;
+}
+
+static int mshv_vp_irq_set_vector(struct mshv_vp *vp, u32 vector)
+{
+	int ret;
+
+	do {
+		ret = mshv_vp_irq_try_set_vector(vp, vector);
+	} while (ret == -EAGAIN && !need_resched());
+
+	return ret;
+}
+
+/*
+ * Try to raise irq for guest via shared vector array. hyp does the actual
+ * inject of the interrupt.
+ */
+static int mshv_try_assert_irq_fast(struct mshv_irqfd *irqfd)
+{
+	struct mshv_partition *partition = irqfd->irqfd_partn;
+	struct mshv_lapic_irq *irq = &irqfd->irqfd_lapic_irq;
+	struct mshv_vp *vp;
+
+	if (!(ms_hyperv.ext_features &
+	      HV_VP_DISPATCH_INTERRUPT_INJECTION_AVAILABLE))
+		return -EOPNOTSUPP;
+
+	if (hv_scheduler_type != HV_SCHEDULER_TYPE_ROOT)
+		return -EOPNOTSUPP;
+
+#if IS_ENABLED(CONFIG_X86)
+	if (irq->lapic_control.logical_dest_mode)
+		return -EOPNOTSUPP;
+#endif
+
+	/*
+	 * Pairs with smp_store_release() in mshv_partition_ioctl_create_vp().
+	 * MSHV_IRQFD does not require the target lapic_apic_id to refer to an
+	 * existing VP, so this read can race a concurrent VP creation; the
+	 * acquire ensures that a non-NULL pointer implies the VP's
+	 * initialising stores are visible.
+	 */
+	vp = smp_load_acquire(&partition->pt_vp_array[irq->lapic_apic_id]);
+
+	if (!vp->vp_register_page)
+		return -EOPNOTSUPP;
+
+	if (mshv_vp_irq_set_vector(vp, irq->lapic_vector))
+		return -EINVAL;
+
+	if (vp->run.flags.root_sched_dispatched &&
+	    vp->vp_register_page->interrupt_vectors.as_uint64)
+		return -EBUSY;
+
+	wake_up(&vp->run.vp_suspend_queue);
+
+	return 0;
+}
+#else /* CONFIG_X86_64 */
+static int mshv_try_assert_irq_fast(struct mshv_irqfd *irqfd)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+static void mshv_assert_irq_slow(struct mshv_irqfd *irqfd)
+{
+	struct mshv_partition *partition = irqfd->irqfd_partn;
+	struct mshv_lapic_irq *irq = &irqfd->irqfd_lapic_irq;
+	unsigned int seq;
+	int idx;
+
+#if IS_ENABLED(CONFIG_X86)
+	WARN_ON(irqfd->irqfd_resampler &&
+		!irq->lapic_control.level_triggered);
+#endif
+
+	idx = srcu_read_lock(&partition->pt_irq_srcu);
+	if (irqfd->irqfd_girq_ent.guest_irq_num) {
+		if (!irqfd->irqfd_girq_ent.girq_entry_valid) {
+			srcu_read_unlock(&partition->pt_irq_srcu, idx);
+			return;
+		}
+
+		do {
+			seq = read_seqcount_begin(&irqfd->irqfd_irqe_sc);
+		} while (read_seqcount_retry(&irqfd->irqfd_irqe_sc, seq));
+	}
+
+	hv_call_assert_virtual_interrupt(irqfd->irqfd_partn->pt_id,
+					 irq->lapic_vector, irq->lapic_apic_id,
+					 irq->lapic_control);
+	srcu_read_unlock(&partition->pt_irq_srcu, idx);
+}
+
+static void mshv_irqfd_resampler_shutdown(struct mshv_irqfd *irqfd)
+{
+	struct mshv_irqfd_resampler *rp = irqfd->irqfd_resampler;
+	struct mshv_partition *pt = rp->rsmplr_partn;
+
+	mutex_lock(&pt->irqfds_resampler_lock);
+
+	hlist_del_rcu(&irqfd->irqfd_resampler_hnode);
+	synchronize_srcu(&pt->pt_irq_srcu);
+
+	if (hlist_empty(&rp->rsmplr_irqfd_list)) {
+		hlist_del(&rp->rsmplr_hnode);
+		mshv_unregister_irq_ack_notifier(pt, &rp->rsmplr_notifier);
+		kfree(rp);
+	}
+
+	mutex_unlock(&pt->irqfds_resampler_lock);
+}
+
+/*
+ * Race-free decouple logic (ordering is critical)
+ */
+static void mshv_irqfd_shutdown(struct work_struct *work)
+{
+	struct mshv_irqfd *irqfd =
+			container_of(work, struct mshv_irqfd, irqfd_shutdown);
+	u64 cnt;
+
+	/*
+	 * Synchronize with the wait-queue and unhook ourselves to prevent
+	 * further events.
+	 */
+	eventfd_ctx_remove_wait_queue(irqfd->irqfd_eventfd_ctx, &irqfd->irqfd_wait, &cnt);
+
+	if (irqfd->irqfd_resampler) {
+		mshv_irqfd_resampler_shutdown(irqfd);
+		eventfd_ctx_put(irqfd->irqfd_resamplefd);
+	}
+
+	/*
+	 * It is now safe to release the object's resources
+	 */
+	eventfd_ctx_put(irqfd->irqfd_eventfd_ctx);
+	kfree(irqfd);
+}
+
+/* assumes partition->pt_irqfds_lock is held */
+static bool mshv_irqfd_is_active(struct mshv_irqfd *irqfd)
+{
+	return !hlist_unhashed(&irqfd->irqfd_hnode);
+}
+
+/*
+ * Mark the irqfd as inactive and schedule it for removal
+ *
+ * assumes partition->pt_irqfds_lock is held
+ */
+static void mshv_irqfd_deactivate(struct mshv_irqfd *irqfd)
+{
+	if (!mshv_irqfd_is_active(irqfd))
+		return;
+
+	hlist_del_init(&irqfd->irqfd_hnode);
+
+	queue_work(irqfd_cleanup_wq, &irqfd->irqfd_shutdown);
+}
+
+/*
+ * Called with wqh->lock held and interrupts disabled
+ */
+static int mshv_irqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode,
+			     int sync, void *key)
+{
+	struct mshv_irqfd *irqfd = container_of(wait, struct mshv_irqfd,
+						irqfd_wait);
+	__poll_t flags = key_to_poll(key);
+	int idx;
+	unsigned int seq;
+	struct mshv_partition *pt = irqfd->irqfd_partn;
+	int ret = 0;
+
+	if (flags & EPOLLIN) {
+		u64 cnt;
+
+		eventfd_ctx_do_read(irqfd->irqfd_eventfd_ctx, &cnt);
+		idx = srcu_read_lock(&pt->pt_irq_srcu);
+		do {
+			seq = read_seqcount_begin(&irqfd->irqfd_irqe_sc);
+		} while (read_seqcount_retry(&irqfd->irqfd_irqe_sc, seq));
+
+		/* An event has been signaled, raise an interrupt */
+		ret = mshv_try_assert_irq_fast(irqfd);
+		if (ret)
+			mshv_assert_irq_slow(irqfd);
+
+		srcu_read_unlock(&pt->pt_irq_srcu, idx);
+
+		ret = 1;
+	}
+
+	if (flags & EPOLLHUP) {
+		/* The eventfd is closing, detach from the partition */
+		unsigned long flags;
+
+		spin_lock_irqsave(&pt->pt_irqfds_lock, flags);
+
+		/*
+		 * We must check if someone deactivated the irqfd before
+		 * we could acquire the pt_irqfds_lock since the item is
+		 * deactivated from the mshv side before it is unhooked from
+		 * the wait-queue.  If it is already deactivated, we can
+		 * simply return knowing the other side will cleanup for us.
+		 * We cannot race against the irqfd going away since the
+		 * other side is required to acquire wqh->lock, which we hold
+		 */
+		if (mshv_irqfd_is_active(irqfd))
+			mshv_irqfd_deactivate(irqfd);
+
+		spin_unlock_irqrestore(&pt->pt_irqfds_lock, flags);
+	}
+
+	return ret;
+}
+
+/* Must be called under pt_irqfds_lock */
+static void mshv_irqfd_update(struct mshv_partition *pt,
+			      struct mshv_irqfd *irqfd)
+{
+	write_seqcount_begin(&irqfd->irqfd_irqe_sc);
+	irqfd->irqfd_girq_ent = mshv_ret_girq_entry(pt,
+						    irqfd->irqfd_irqnum);
+	mshv_copy_girq_info(&irqfd->irqfd_girq_ent, &irqfd->irqfd_lapic_irq);
+	write_seqcount_end(&irqfd->irqfd_irqe_sc);
+}
+
+void mshv_irqfd_routing_update(struct mshv_partition *pt)
+{
+	struct mshv_irqfd *irqfd;
+
+	spin_lock_irq(&pt->pt_irqfds_lock);
+	hlist_for_each_entry(irqfd, &pt->pt_irqfds_list, irqfd_hnode)
+		mshv_irqfd_update(pt, irqfd);
+	spin_unlock_irq(&pt->pt_irqfds_lock);
+}
+
+static void mshv_irqfd_queue_proc(struct file *file, wait_queue_head_t *wqh,
+				  poll_table *polltbl)
+{
+	struct mshv_irqfd *irqfd =
+			container_of(polltbl, struct mshv_irqfd, irqfd_polltbl);
+
+	/*
+	 * TODO: Ensure there isn't already an exclusive, priority waiter, e.g.
+	 * that the irqfd isn't already bound to another partition.  Only the
+	 * first exclusive waiter encountered will be notified, and
+	 * add_wait_queue_priority() doesn't enforce exclusivity.
+	 */
+	irqfd->irqfd_wait.flags |= WQ_FLAG_EXCLUSIVE;
+	add_wait_queue_priority(wqh, &irqfd->irqfd_wait);
+}
+
+static int mshv_irqfd_assign(struct mshv_partition *pt,
+			     struct mshv_user_irqfd *args)
+{
+	struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
+	struct mshv_irqfd *irqfd, *tmp;
+	__poll_t events;
+	int ret;
+	int idx;
+
+	CLASS(fd, f)(args->fd);
+
+	irqfd = kzalloc_obj(*irqfd);
+	if (!irqfd)
+		return -ENOMEM;
+
+	irqfd->irqfd_partn = pt;
+	irqfd->irqfd_irqnum = args->gsi;
+	INIT_WORK(&irqfd->irqfd_shutdown, mshv_irqfd_shutdown);
+	seqcount_spinlock_init(&irqfd->irqfd_irqe_sc, &pt->pt_irqfds_lock);
+
+	if (fd_empty(f)) {
+		ret = -EBADF;
+		goto out;
+	}
+
+	eventfd = eventfd_ctx_fileget(fd_file(f));
+	if (IS_ERR(eventfd)) {
+		ret = PTR_ERR(eventfd);
+		goto fail;
+	}
+
+	irqfd->irqfd_eventfd_ctx = eventfd;
+
+	if (args->flags & BIT(MSHV_IRQFD_BIT_RESAMPLE)) {
+		struct mshv_irqfd_resampler *rp;
+
+		resamplefd = eventfd_ctx_fdget(args->resamplefd);
+		if (IS_ERR(resamplefd)) {
+			ret = PTR_ERR(resamplefd);
+			goto fail;
+		}
+
+		irqfd->irqfd_resamplefd = resamplefd;
+
+		mutex_lock(&pt->irqfds_resampler_lock);
+
+		hlist_for_each_entry(rp, &pt->irqfds_resampler_list,
+				     rsmplr_hnode) {
+			if (rp->rsmplr_notifier.irq_ack_gsi ==
+							 irqfd->irqfd_irqnum) {
+				irqfd->irqfd_resampler = rp;
+				break;
+			}
+		}
+
+		if (!irqfd->irqfd_resampler) {
+			rp = kzalloc_obj(*rp, GFP_KERNEL_ACCOUNT);
+			if (!rp) {
+				ret = -ENOMEM;
+				mutex_unlock(&pt->irqfds_resampler_lock);
+				goto fail;
+			}
+
+			rp->rsmplr_partn = pt;
+			INIT_HLIST_HEAD(&rp->rsmplr_irqfd_list);
+			rp->rsmplr_notifier.irq_ack_gsi = irqfd->irqfd_irqnum;
+			rp->rsmplr_notifier.irq_acked =
+						      mshv_irqfd_resampler_ack;
+
+			hlist_add_head(&rp->rsmplr_hnode,
+				       &pt->irqfds_resampler_list);
+			mshv_register_irq_ack_notifier(pt,
+						       &rp->rsmplr_notifier);
+			irqfd->irqfd_resampler = rp;
+		}
+
+		hlist_add_head_rcu(&irqfd->irqfd_resampler_hnode,
+				   &irqfd->irqfd_resampler->rsmplr_irqfd_list);
+
+		mutex_unlock(&pt->irqfds_resampler_lock);
+	}
+
+	/*
+	 * Install our own custom wake-up handling so we are notified via
+	 * a callback whenever someone signals the underlying eventfd
+	 */
+	init_waitqueue_func_entry(&irqfd->irqfd_wait, mshv_irqfd_wakeup);
+	init_poll_funcptr(&irqfd->irqfd_polltbl, mshv_irqfd_queue_proc);
+
+	spin_lock_irq(&pt->pt_irqfds_lock);
+	ret = 0;
+	hlist_for_each_entry(tmp, &pt->pt_irqfds_list, irqfd_hnode) {
+		if (irqfd->irqfd_eventfd_ctx != tmp->irqfd_eventfd_ctx)
+			continue;
+		/* This fd is used for another irq already. */
+		ret = -EBUSY;
+		spin_unlock_irq(&pt->pt_irqfds_lock);
+		goto fail;
+	}
+
+	idx = srcu_read_lock(&pt->pt_irq_srcu);
+	mshv_irqfd_update(pt, irqfd);
+
+#if IS_ENABLED(CONFIG_X86)
+	if (args->flags & BIT(MSHV_IRQFD_BIT_RESAMPLE) &&
+	    !irqfd->irqfd_lapic_irq.lapic_control.level_triggered) {
+		/*
+		 * Resample Fd must be for level triggered interrupt
+		 * Otherwise return with failure
+		 */
+		spin_unlock_irq(&pt->pt_irqfds_lock);
+		srcu_read_unlock(&pt->pt_irq_srcu, idx);
+		ret = -EINVAL;
+		goto fail;
+	}
+#endif
+
+	hlist_add_head(&irqfd->irqfd_hnode, &pt->pt_irqfds_list);
+	spin_unlock_irq(&pt->pt_irqfds_lock);
+
+	/*
+	 * Check if there was an event already pending on the eventfd
+	 * before we registered, and trigger it as if we didn't miss it.
+	 */
+	events = vfs_poll(fd_file(f), &irqfd->irqfd_polltbl);
+
+	if (events & EPOLLIN)
+		mshv_assert_irq_slow(irqfd);
+
+	srcu_read_unlock(&pt->pt_irq_srcu, idx);
+	return 0;
+
+fail:
+	if (irqfd->irqfd_resampler)
+		mshv_irqfd_resampler_shutdown(irqfd);
+
+	if (resamplefd && !IS_ERR(resamplefd))
+		eventfd_ctx_put(resamplefd);
+
+	if (eventfd && !IS_ERR(eventfd))
+		eventfd_ctx_put(eventfd);
+
+out:
+	kfree(irqfd);
+	return ret;
+}
+
+/*
+ * shutdown any irqfd's that match fd+gsi
+ */
+static int mshv_irqfd_deassign(struct mshv_partition *pt,
+			       struct mshv_user_irqfd *args)
+{
+	struct mshv_irqfd *irqfd;
+	struct hlist_node *n;
+	struct eventfd_ctx *eventfd;
+
+	eventfd = eventfd_ctx_fdget(args->fd);
+	if (IS_ERR(eventfd))
+		return PTR_ERR(eventfd);
+
+	spin_lock_irq(&pt->pt_irqfds_lock);
+	hlist_for_each_entry_safe(irqfd, n, &pt->pt_irqfds_list,
+				  irqfd_hnode) {
+		if (irqfd->irqfd_eventfd_ctx == eventfd &&
+		    irqfd->irqfd_irqnum == args->gsi)
+			mshv_irqfd_deactivate(irqfd);
+	}
+	spin_unlock_irq(&pt->pt_irqfds_lock);
+
+	eventfd_ctx_put(eventfd);
+
+	/*
+	 * Block until we know all outstanding shutdown jobs have completed
+	 * so that we guarantee there will not be any more interrupts on this
+	 * gsi once this deassign function returns.
+	 */
+	flush_workqueue(irqfd_cleanup_wq);
+
+	return 0;
+}
+
+int mshv_set_unset_irqfd(struct mshv_partition *pt,
+			 struct mshv_user_irqfd *args)
+{
+	if (args->flags & ~MSHV_IRQFD_FLAGS_MASK)
+		return -EINVAL;
+
+	if (args->flags & BIT(MSHV_IRQFD_BIT_DEASSIGN))
+		return mshv_irqfd_deassign(pt, args);
+
+	return mshv_irqfd_assign(pt, args);
+}
+
+/*
+ * This function is called as the mshv VM fd is being released.
+ * Shutdown all irqfds that still remain open
+ */
+static void mshv_irqfd_release(struct mshv_partition *pt)
+{
+	struct mshv_irqfd *irqfd;
+	struct hlist_node *n;
+
+	spin_lock_irq(&pt->pt_irqfds_lock);
+
+	hlist_for_each_entry_safe(irqfd, n, &pt->pt_irqfds_list, irqfd_hnode)
+		mshv_irqfd_deactivate(irqfd);
+
+	spin_unlock_irq(&pt->pt_irqfds_lock);
+
+	/*
+	 * Block until we know all outstanding shutdown jobs have completed
+	 * since we do not take a mshv_partition* reference.
+	 */
+	flush_workqueue(irqfd_cleanup_wq);
+}
+
+int mshv_irqfd_wq_init(void)
+{
+	irqfd_cleanup_wq = alloc_workqueue("mshv-irqfd-cleanup", WQ_PERCPU, 0);
+	if (!irqfd_cleanup_wq)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void mshv_irqfd_wq_cleanup(void)
+{
+	destroy_workqueue(irqfd_cleanup_wq);
+}
+
+/*
+ * --------------------------------------------------------------------
+ * ioeventfd: translate a MMIO memory write to an eventfd signal.
+ *
+ * userspace can register a MMIO address with an eventfd for receiving
+ * notification when the memory has been touched.
+ * --------------------------------------------------------------------
+ */
+
+static void ioeventfd_release(struct mshv_ioeventfd *p, u64 partition_id)
+{
+	if (p->iovntfd_doorbell_id > 0)
+		mshv_unregister_doorbell(partition_id, p->iovntfd_doorbell_id);
+	eventfd_ctx_put(p->iovntfd_eventfd);
+	kfree(p);
+}
+
+/* MMIO writes trigger an event if the addr/val match */
+static void ioeventfd_mmio_write(int doorbell_id, void *data)
+{
+	struct mshv_partition *partition = (struct mshv_partition *)data;
+	struct mshv_ioeventfd *p;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(p, &partition->ioeventfds_list, iovntfd_hnode)
+		if (p->iovntfd_doorbell_id == doorbell_id) {
+			eventfd_signal(p->iovntfd_eventfd);
+			break;
+		}
+
+	rcu_read_unlock();
+}
+
+static bool ioeventfd_check_collision(struct mshv_partition *pt,
+				      struct mshv_ioeventfd *p)
+	__must_hold(&pt->mutex)
+{
+	struct mshv_ioeventfd *_p;
+
+	hlist_for_each_entry(_p, &pt->ioeventfds_list, iovntfd_hnode)
+		if (_p->iovntfd_addr == p->iovntfd_addr &&
+		    _p->iovntfd_length == p->iovntfd_length &&
+		    (_p->iovntfd_wildcard || p->iovntfd_wildcard ||
+		     _p->iovntfd_datamatch == p->iovntfd_datamatch))
+			return true;
+
+	return false;
+}
+
+static int mshv_assign_ioeventfd(struct mshv_partition *pt,
+				 struct mshv_user_ioeventfd *args)
+	__must_hold(&pt->mutex)
+{
+	struct mshv_ioeventfd *p;
+	struct eventfd_ctx *eventfd;
+	u64 doorbell_flags = 0;
+	int ret;
+
+	/* This mutex is currently protecting ioeventfd.items list */
+	WARN_ON_ONCE(!mutex_is_locked(&pt->pt_mutex));
+
+	if (args->flags & BIT(MSHV_IOEVENTFD_BIT_PIO))
+		return -EOPNOTSUPP;
+
+	/* must be natural-word sized */
+	switch (args->len) {
+	case 0:
+		doorbell_flags = HV_DOORBELL_FLAG_TRIGGER_SIZE_ANY;
+		break;
+	case 1:
+		doorbell_flags = HV_DOORBELL_FLAG_TRIGGER_SIZE_BYTE;
+		break;
+	case 2:
+		doorbell_flags = HV_DOORBELL_FLAG_TRIGGER_SIZE_WORD;
+		break;
+	case 4:
+		doorbell_flags = HV_DOORBELL_FLAG_TRIGGER_SIZE_DWORD;
+		break;
+	case 8:
+		doorbell_flags = HV_DOORBELL_FLAG_TRIGGER_SIZE_QWORD;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* check for range overflow */
+	if (args->addr + args->len < args->addr)
+		return -EINVAL;
+
+	/* check for extra flags that we don't understand */
+	if (args->flags & ~MSHV_IOEVENTFD_FLAGS_MASK)
+		return -EINVAL;
+
+	eventfd = eventfd_ctx_fdget(args->fd);
+	if (IS_ERR(eventfd))
+		return PTR_ERR(eventfd);
+
+	p = kzalloc_obj(*p);
+	if (!p) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	p->iovntfd_addr = args->addr;
+	p->iovntfd_length  = args->len;
+	p->iovntfd_eventfd = eventfd;
+
+	/* The datamatch feature is optional, otherwise this is a wildcard */
+	if (args->flags & BIT(MSHV_IOEVENTFD_BIT_DATAMATCH)) {
+		p->iovntfd_datamatch = args->datamatch;
+	} else {
+		p->iovntfd_wildcard = true;
+		doorbell_flags |= HV_DOORBELL_FLAG_TRIGGER_ANY_VALUE;
+	}
+
+	if (ioeventfd_check_collision(pt, p)) {
+		ret = -EEXIST;
+		goto unlock_fail;
+	}
+
+	ret = mshv_register_doorbell(pt->pt_id, ioeventfd_mmio_write,
+				     (void *)pt, p->iovntfd_addr,
+				     p->iovntfd_datamatch, doorbell_flags);
+
+	trace_mshv_assign_ioeventfd(pt->pt_id, p->iovntfd_addr,
+				    p->iovntfd_length,
+				    p->iovntfd_datamatch,
+				    p->iovntfd_wildcard,
+				    p->iovntfd_eventfd,
+				    ret);
+
+	if (ret < 0)
+		goto unlock_fail;
+
+	p->iovntfd_doorbell_id = ret;
+
+	hlist_add_head_rcu(&p->iovntfd_hnode, &pt->ioeventfds_list);
+
+	return 0;
+
+unlock_fail:
+	kfree(p);
+
+fail:
+	eventfd_ctx_put(eventfd);
+
+	return ret;
+}
+
+static int mshv_deassign_ioeventfd(struct mshv_partition *pt,
+				   struct mshv_user_ioeventfd *args)
+	__must_hold(&pt->mutex)
+{
+	struct mshv_ioeventfd *p;
+	struct eventfd_ctx *eventfd;
+	struct hlist_node *n;
+	int ret = -ENOENT;
+
+	/* This mutex is currently protecting ioeventfd.items list */
+	WARN_ON_ONCE(!mutex_is_locked(&pt->pt_mutex));
+
+	eventfd = eventfd_ctx_fdget(args->fd);
+	if (IS_ERR(eventfd))
+		return PTR_ERR(eventfd);
+
+	hlist_for_each_entry_safe(p, n, &pt->ioeventfds_list, iovntfd_hnode) {
+		bool wildcard = !(args->flags & BIT(MSHV_IOEVENTFD_BIT_DATAMATCH));
+
+		if (p->iovntfd_eventfd != eventfd  ||
+		    p->iovntfd_addr != args->addr  ||
+		    p->iovntfd_length != args->len ||
+		    p->iovntfd_wildcard != wildcard)
+			continue;
+
+		if (!p->iovntfd_wildcard &&
+		    p->iovntfd_datamatch != args->datamatch)
+			continue;
+
+		trace_mshv_deassign_ioeventfd(pt->pt_id, p->iovntfd_addr,
+					      p->iovntfd_length,
+					      p->iovntfd_datamatch,
+					      p->iovntfd_wildcard,
+					      p->iovntfd_eventfd);
+
+		hlist_del_rcu(&p->iovntfd_hnode);
+		synchronize_rcu();
+		ioeventfd_release(p, pt->pt_id);
+		ret = 0;
+		break;
+	}
+
+	eventfd_ctx_put(eventfd);
+
+	return ret;
+}
+
+int mshv_set_unset_ioeventfd(struct mshv_partition *pt,
+			     struct mshv_user_ioeventfd *args)
+	__must_hold(&pt->mutex)
+{
+	if ((args->flags & ~MSHV_IOEVENTFD_FLAGS_MASK) ||
+	    mshv_field_nonzero(*args, rsvd))
+		return -EINVAL;
+
+	/* PIO not yet implemented */
+	if (args->flags & BIT(MSHV_IOEVENTFD_BIT_PIO))
+		return -EOPNOTSUPP;
+
+	if (args->flags & BIT(MSHV_IOEVENTFD_BIT_DEASSIGN))
+		return mshv_deassign_ioeventfd(pt, args);
+
+	return mshv_assign_ioeventfd(pt, args);
+}
+
+void mshv_eventfd_init(struct mshv_partition *pt)
+{
+	spin_lock_init(&pt->pt_irqfds_lock);
+	INIT_HLIST_HEAD(&pt->pt_irqfds_list);
+
+	INIT_HLIST_HEAD(&pt->irqfds_resampler_list);
+	mutex_init(&pt->irqfds_resampler_lock);
+
+	INIT_HLIST_HEAD(&pt->ioeventfds_list);
+}
+
+void mshv_eventfd_release(struct mshv_partition *pt)
+{
+	struct hlist_head items;
+	struct hlist_node *n;
+	struct mshv_ioeventfd *p;
+
+	hlist_move_list(&pt->ioeventfds_list, &items);
+	synchronize_rcu();
+
+	hlist_for_each_entry_safe(p, n, &items, iovntfd_hnode) {
+		hlist_del(&p->iovntfd_hnode);
+		ioeventfd_release(p, pt->pt_id);
+	}
+
+	mshv_irqfd_release(pt);
+}
diff --git a/drivers/hv/mshv_eventfd.h b/drivers/hv/mshv_eventfd.h
new file mode 100644
index 000000000..464c6b81a
--- /dev/null
+++ b/drivers/hv/mshv_eventfd.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * irqfd: Allows an fd to be used to inject an interrupt to the guest.
+ * ioeventfd: Allow an fd to be used to receive a signal from the guest.
+ * All credit goes to kvm developers.
+ */
+
+#ifndef __LINUX_MSHV_EVENTFD_H
+#define __LINUX_MSHV_EVENTFD_H
+
+#include <linux/poll.h>
+
+#include "mshv.h"
+#include "mshv_root.h"
+
+/* struct to contain list of irqfds sharing an irq. Updates are protected by
+ * partition.irqfds.resampler_lock
+ */
+struct mshv_irqfd_resampler {
+	struct mshv_partition	    *rsmplr_partn;
+	struct hlist_head	     rsmplr_irqfd_list;
+	struct mshv_irq_ack_notifier rsmplr_notifier;
+	struct hlist_node	     rsmplr_hnode;
+};
+
+struct mshv_irqfd {
+	struct mshv_partition		    *irqfd_partn;
+	struct eventfd_ctx		    *irqfd_eventfd_ctx;
+	struct mshv_guest_irq_ent	     irqfd_girq_ent;
+	seqcount_spinlock_t		     irqfd_irqe_sc;
+	u32				     irqfd_irqnum;
+	struct mshv_lapic_irq		     irqfd_lapic_irq;
+	struct hlist_node		     irqfd_hnode;
+	poll_table			     irqfd_polltbl;
+	wait_queue_entry_t		     irqfd_wait;
+	struct work_struct		     irqfd_shutdown;
+	struct mshv_irqfd_resampler	    *irqfd_resampler;
+	struct eventfd_ctx		    *irqfd_resamplefd;
+	struct hlist_node		     irqfd_resampler_hnode;
+};
+
+void mshv_eventfd_init(struct mshv_partition *partition);
+void mshv_eventfd_release(struct mshv_partition *partition);
+
+void mshv_register_irq_ack_notifier(struct mshv_partition *partition,
+				    struct mshv_irq_ack_notifier *mian);
+void mshv_unregister_irq_ack_notifier(struct mshv_partition *partition,
+				      struct mshv_irq_ack_notifier *mian);
+bool mshv_notify_acked_gsi(struct mshv_partition *partition, int gsi);
+
+int mshv_set_unset_irqfd(struct mshv_partition *partition,
+			 struct mshv_user_irqfd *args);
+
+int mshv_irqfd_wq_init(void);
+void mshv_irqfd_wq_cleanup(void);
+
+struct mshv_ioeventfd {
+	struct hlist_node    iovntfd_hnode;
+	u64		     iovntfd_addr;
+	int		     iovntfd_length;
+	struct eventfd_ctx  *iovntfd_eventfd;
+	u64		     iovntfd_datamatch;
+	int		     iovntfd_doorbell_id;
+	bool		     iovntfd_wildcard;
+};
+
+int mshv_set_unset_ioeventfd(struct mshv_partition *pt,
+			     struct mshv_user_ioeventfd *args);
+
+#endif /* __LINUX_MSHV_EVENTFD_H */
diff --git a/drivers/hv/mshv_irq.c b/drivers/hv/mshv_irq.c
new file mode 100644
index 000000000..65a4ffc82
--- /dev/null
+++ b/drivers/hv/mshv_irq.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/mshyperv.h>
+
+#include "mshv_eventfd.h"
+#include "mshv.h"
+#include "mshv_root.h"
+
+/* called from the ioctl code, user wants to update the guest irq table */
+int mshv_update_routing_table(struct mshv_partition *partition,
+			      const struct mshv_user_irq_entry *ue,
+			      unsigned int numents)
+{
+	struct mshv_girq_routing_table *new = NULL, *old;
+	u32 i, nr_rt_entries = 0;
+	int r = 0;
+
+	if (numents == 0)
+		goto swap_routes;
+
+	for (i = 0; i < numents; i++) {
+		if (ue[i].gsi >= MSHV_MAX_GUEST_IRQS)
+			return -EINVAL;
+
+		if (ue[i].address_hi)
+			return -EINVAL;
+
+		nr_rt_entries = max(nr_rt_entries, ue[i].gsi);
+	}
+	nr_rt_entries += 1;
+
+	new = kzalloc_flex(*new, mshv_girq_info_tbl, nr_rt_entries,
+			   GFP_KERNEL_ACCOUNT);
+	if (!new)
+		return -ENOMEM;
+
+	new->num_rt_entries = nr_rt_entries;
+	for (i = 0; i < numents; i++) {
+		struct mshv_guest_irq_ent *girq;
+
+		girq = &new->mshv_girq_info_tbl[ue[i].gsi];
+
+		/*
+		 * Allow only one to one mapping between GSI and MSI routing.
+		 */
+		if (girq->girq_entry_valid) {
+			r = -EINVAL;
+			goto out;
+		}
+
+		girq->guest_irq_num = ue[i].gsi;
+		girq->girq_addr_lo = ue[i].address_lo;
+		girq->girq_addr_hi = ue[i].address_hi;
+		girq->girq_irq_data = ue[i].data;
+		girq->girq_entry_valid = true;
+	}
+
+swap_routes:
+	mutex_lock(&partition->pt_irq_lock);
+	old = rcu_dereference_protected(partition->pt_girq_tbl, 1);
+	rcu_assign_pointer(partition->pt_girq_tbl, new);
+	mshv_irqfd_routing_update(partition);
+	mutex_unlock(&partition->pt_irq_lock);
+
+	synchronize_srcu_expedited(&partition->pt_irq_srcu);
+
+	trace_mshv_update_routing_table(partition->pt_id,
+					old, new, numents);
+
+	new = old;
+
+out:
+	kfree(new);
+
+	return r;
+}
+
+/* vm is going away, kfree the irq routing table */
+void mshv_free_routing_table(struct mshv_partition *partition)
+{
+	struct mshv_girq_routing_table *rt =
+				   rcu_access_pointer(partition->pt_girq_tbl);
+
+	kfree(rt);
+}
+
+struct mshv_guest_irq_ent
+mshv_ret_girq_entry(struct mshv_partition *partition, u32 irqnum)
+{
+	struct mshv_guest_irq_ent entry = { 0 };
+	struct mshv_girq_routing_table *girq_tbl;
+
+	girq_tbl = srcu_dereference_check(partition->pt_girq_tbl,
+					  &partition->pt_irq_srcu,
+					  lockdep_is_held(&partition->pt_irq_lock));
+	if (!girq_tbl || irqnum >= girq_tbl->num_rt_entries) {
+		/*
+		 * Premature register_irqfd, setting valid_entry = 0
+		 * would ignore this entry anyway
+		 */
+		entry.guest_irq_num = irqnum;
+		return entry;
+	}
+
+	return girq_tbl->mshv_girq_info_tbl[irqnum];
+}
+
+void mshv_copy_girq_info(struct mshv_guest_irq_ent *ent,
+			 struct mshv_lapic_irq *lirq)
+{
+	memset(lirq, 0, sizeof(*lirq));
+	if (!ent || !ent->girq_entry_valid)
+		return;
+
+	lirq->lapic_vector = ent->girq_irq_data & 0xFF;
+	lirq->lapic_apic_id = (ent->girq_addr_lo >> 12) & 0xFF;
+	lirq->lapic_control.interrupt_type = (ent->girq_irq_data & 0x700) >> 8;
+#if IS_ENABLED(CONFIG_X86)
+	lirq->lapic_control.level_triggered = (ent->girq_irq_data >> 15) & 0x1;
+	lirq->lapic_control.logical_dest_mode = (ent->girq_addr_lo >> 2) & 0x1;
+#elif IS_ENABLED(CONFIG_ARM64)
+	lirq->lapic_control.asserted = 1;
+#endif
+}
diff --git a/drivers/hv/mshv_portid_table.c b/drivers/hv/mshv_portid_table.c
new file mode 100644
index 000000000..0d632507e
--- /dev/null
+++ b/drivers/hv/mshv_portid_table.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <asm/mshyperv.h>
+
+#include "mshv.h"
+#include "mshv_root.h"
+
+/*
+ * Ports and connections are hypervisor struct used for inter-partition
+ * communication. Port represents the source and connection represents
+ * the destination. Partitions are responsible for managing the port and
+ * connection ids.
+ *
+ */
+
+#define PORTID_MIN	1
+#define PORTID_MAX	INT_MAX
+
+static DEFINE_IDR(port_table_idr);
+
+void
+mshv_port_table_fini(void)
+{
+	struct port_table_info *port_info;
+	unsigned long i, tmp;
+
+	idr_lock(&port_table_idr);
+	if (!idr_is_empty(&port_table_idr)) {
+		idr_for_each_entry_ul(&port_table_idr, port_info, tmp, i) {
+			port_info = idr_remove(&port_table_idr, i);
+			kfree_rcu(port_info, portbl_rcu);
+		}
+	}
+	idr_unlock(&port_table_idr);
+}
+
+int
+mshv_portid_alloc(struct port_table_info *info)
+{
+	int ret;
+
+	idr_preload(GFP_KERNEL);
+	idr_lock(&port_table_idr);
+	ret = idr_alloc(&port_table_idr, info, PORTID_MIN,
+			PORTID_MAX, GFP_NOWAIT);
+	idr_unlock(&port_table_idr);
+	idr_preload_end();
+
+	return ret;
+}
+
+void
+mshv_portid_free(int port_id)
+{
+	struct port_table_info *info;
+
+	idr_lock(&port_table_idr);
+	info = idr_remove(&port_table_idr, port_id);
+	WARN_ON(!info);
+	idr_unlock(&port_table_idr);
+
+	kfree_rcu(info, portbl_rcu);
+}
+
+int
+mshv_portid_lookup(int port_id, struct port_table_info *info)
+{
+	struct port_table_info *_info;
+	int ret = -ENOENT;
+
+	rcu_read_lock();
+	_info = idr_find(&port_table_idr, port_id);
+	rcu_read_unlock();
+
+	if (_info) {
+		*info = *_info;
+		ret = 0;
+	}
+
+	return ret;
+}
diff --git a/drivers/hv/mshv_regions.c b/drivers/hv/mshv_regions.c
new file mode 100644
index 000000000..dddaade31
--- /dev/null
+++ b/drivers/hv/mshv_regions.c
@@ -0,0 +1,553 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2025, Microsoft Corporation.
+ *
+ * Memory region management for mshv_root module.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/hmm.h>
+#include <linux/hyperv.h>
+#include <linux/kref.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+
+#include <asm/mshyperv.h>
+
+#include "mshv_root.h"
+
+#define MSHV_MAP_FAULT_IN_PAGES				PTRS_PER_PMD
+
+/**
+ * mshv_chunk_stride - Compute stride for mapping guest memory
+ * @page      : The page to check for huge page backing
+ * @gfn       : Guest frame number for the mapping
+ * @page_count: Total number of pages in the mapping
+ *
+ * Determines the appropriate stride (in pages) for mapping guest memory.
+ * Uses huge page stride if the backing page is huge and the guest mapping
+ * is properly aligned; otherwise falls back to single page stride.
+ *
+ * Return: Stride in pages.
+ */
+static unsigned int mshv_chunk_stride(struct page *page, u64 gfn,
+				      u64 page_count)
+{
+	unsigned int page_order = folio_order(page_folio(page));
+
+	/*
+	 * Use single page stride by default. For huge page stride, the
+	 * folio order must be at least PMD_ORDER, the page's PFN must be
+	 * 2M-aligned (so that a 2M-aligned tail page of a larger folio is
+	 * acceptable), and both gfn and page_count must be 2M-aligned.
+	 */
+	if (page_order < PMD_ORDER ||
+	    !IS_ALIGNED(page_to_pfn(page), PTRS_PER_PMD) ||
+	    !IS_ALIGNED(gfn, PTRS_PER_PMD) ||
+	    !IS_ALIGNED(page_count, PTRS_PER_PMD))
+		return 1;
+
+	/* Use 2M stride always i.e. process 1G folios as 2M chunks */
+	return 1 << PMD_ORDER;
+}
+
+/**
+ * mshv_region_process_chunk - Processes a contiguous chunk of memory pages
+ *                             in a region.
+ * @region     : Pointer to the memory region structure.
+ * @flags      : Flags to pass to the handler.
+ * @page_offset: Offset into the region's pages array to start processing.
+ * @page_count : Number of pages to process.
+ * @handler    : Callback function to handle the chunk.
+ *
+ * This function scans the region's pages starting from @page_offset,
+ * checking for contiguous present pages of the same size (normal or huge).
+ * It invokes @handler for the chunk of contiguous pages found. Returns the
+ * number of pages handled, or a negative error code if the first page is
+ * not present or the handler fails.
+ *
+ * Note: The @handler callback must be able to handle both normal and huge
+ * pages.
+ *
+ * Return: Number of pages handled, or negative error code.
+ */
+static long mshv_region_process_chunk(struct mshv_mem_region *region,
+				      u32 flags,
+				      u64 page_offset, u64 page_count,
+				      int (*handler)(struct mshv_mem_region *region,
+						     u32 flags,
+						     u64 page_offset,
+						     u64 page_count,
+						     bool huge_page))
+{
+	u64 gfn = region->start_gfn + page_offset;
+	u64 count;
+	struct page *page;
+	unsigned int stride;
+	int ret;
+
+	page = region->mreg_pages[page_offset];
+	if (!page)
+		return -EINVAL;
+
+	stride = mshv_chunk_stride(page, gfn, page_count);
+
+	/* Start at stride since the first stride is validated */
+	for (count = stride; count < page_count; count += stride) {
+		page = region->mreg_pages[page_offset + count];
+
+		/* Break if current page is not present */
+		if (!page)
+			break;
+
+		/* Break if stride size changes */
+		if (stride != mshv_chunk_stride(page, gfn + count,
+						page_count - count))
+			break;
+	}
+
+	ret = handler(region, flags, page_offset, count, stride > 1);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+/**
+ * mshv_region_process_range - Processes a range of memory pages in a
+ *                             region.
+ * @region     : Pointer to the memory region structure.
+ * @flags      : Flags to pass to the handler.
+ * @page_offset: Offset into the region's pages array to start processing.
+ * @page_count : Number of pages to process.
+ * @handler    : Callback function to handle each chunk of contiguous
+ *               pages.
+ *
+ * Iterates over the specified range of pages in @region, skipping
+ * non-present pages. For each contiguous chunk of present pages, invokes
+ * @handler via mshv_region_process_chunk.
+ *
+ * Note: The @handler callback must be able to handle both normal and huge
+ * pages.
+ *
+ * Returns 0 on success, or a negative error code on failure.
+ */
+static int mshv_region_process_range(struct mshv_mem_region *region,
+				     u32 flags,
+				     u64 page_offset, u64 page_count,
+				     int (*handler)(struct mshv_mem_region *region,
+						    u32 flags,
+						    u64 page_offset,
+						    u64 page_count,
+						    bool huge_page))
+{
+	long ret;
+
+	if (page_offset + page_count > region->nr_pages)
+		return -EINVAL;
+
+	while (page_count) {
+		/* Skip non-present pages */
+		if (!region->mreg_pages[page_offset]) {
+			page_offset++;
+			page_count--;
+			continue;
+		}
+
+		ret = mshv_region_process_chunk(region, flags,
+						page_offset,
+						page_count,
+						handler);
+		if (ret < 0)
+			return ret;
+
+		page_offset += ret;
+		page_count -= ret;
+	}
+
+	return 0;
+}
+
+struct mshv_mem_region *mshv_region_create(u64 guest_pfn, u64 nr_pages,
+					   u64 uaddr, u32 flags)
+{
+	struct mshv_mem_region *region;
+
+	region = vzalloc(sizeof(*region) + sizeof(struct page *) * nr_pages);
+	if (!region)
+		return ERR_PTR(-ENOMEM);
+
+	region->nr_pages = nr_pages;
+	region->start_gfn = guest_pfn;
+	region->start_uaddr = uaddr;
+	region->hv_map_flags = HV_MAP_GPA_READABLE | HV_MAP_GPA_ADJUSTABLE;
+	if (flags & BIT(MSHV_SET_MEM_BIT_WRITABLE))
+		region->hv_map_flags |= HV_MAP_GPA_WRITABLE;
+	if (flags & BIT(MSHV_SET_MEM_BIT_EXECUTABLE))
+		region->hv_map_flags |= HV_MAP_GPA_EXECUTABLE;
+
+	kref_init(&region->mreg_refcount);
+
+	return region;
+}
+
+static int mshv_region_chunk_share(struct mshv_mem_region *region,
+				   u32 flags,
+				   u64 page_offset, u64 page_count,
+				   bool huge_page)
+{
+	if (huge_page)
+		flags |= HV_MODIFY_SPA_PAGE_HOST_ACCESS_LARGE_PAGE;
+
+	return hv_call_modify_spa_host_access(region->partition->pt_id,
+					      region->mreg_pages + page_offset,
+					      page_count,
+					      HV_MAP_GPA_READABLE |
+					      HV_MAP_GPA_WRITABLE,
+					      flags, true);
+}
+
+int mshv_region_share(struct mshv_mem_region *region)
+{
+	u32 flags = HV_MODIFY_SPA_PAGE_HOST_ACCESS_MAKE_SHARED;
+
+	return mshv_region_process_range(region, flags,
+					 0, region->nr_pages,
+					 mshv_region_chunk_share);
+}
+
+static int mshv_region_chunk_unshare(struct mshv_mem_region *region,
+				     u32 flags,
+				     u64 page_offset, u64 page_count,
+				     bool huge_page)
+{
+	if (huge_page)
+		flags |= HV_MODIFY_SPA_PAGE_HOST_ACCESS_LARGE_PAGE;
+
+	return hv_call_modify_spa_host_access(region->partition->pt_id,
+					      region->mreg_pages + page_offset,
+					      page_count, 0,
+					      flags, false);
+}
+
+int mshv_region_unshare(struct mshv_mem_region *region)
+{
+	u32 flags = HV_MODIFY_SPA_PAGE_HOST_ACCESS_MAKE_EXCLUSIVE;
+
+	return mshv_region_process_range(region, flags,
+					 0, region->nr_pages,
+					 mshv_region_chunk_unshare);
+}
+
+static int mshv_region_chunk_remap(struct mshv_mem_region *region,
+				   u32 flags,
+				   u64 page_offset, u64 page_count,
+				   bool huge_page)
+{
+	if (huge_page)
+		flags |= HV_MAP_GPA_LARGE_PAGE;
+
+	return hv_call_map_gpa_pages(region->partition->pt_id,
+				     region->start_gfn + page_offset,
+				     page_count, flags,
+				     region->mreg_pages + page_offset);
+}
+
+static int mshv_region_remap_pages(struct mshv_mem_region *region,
+				   u32 map_flags,
+				   u64 page_offset, u64 page_count)
+{
+	return mshv_region_process_range(region, map_flags,
+					 page_offset, page_count,
+					 mshv_region_chunk_remap);
+}
+
+int mshv_region_map(struct mshv_mem_region *region)
+{
+	u32 map_flags = region->hv_map_flags;
+
+	return mshv_region_remap_pages(region, map_flags,
+				       0, region->nr_pages);
+}
+
+static void mshv_region_invalidate_pages(struct mshv_mem_region *region,
+					 u64 page_offset, u64 page_count)
+{
+	if (region->mreg_type == MSHV_REGION_TYPE_MEM_PINNED)
+		unpin_user_pages(region->mreg_pages + page_offset, page_count);
+
+	memset(region->mreg_pages + page_offset, 0,
+	       page_count * sizeof(struct page *));
+}
+
+void mshv_region_invalidate(struct mshv_mem_region *region)
+{
+	mshv_region_invalidate_pages(region, 0, region->nr_pages);
+}
+
+int mshv_region_pin(struct mshv_mem_region *region)
+{
+	u64 done_count, nr_pages;
+	struct page **pages;
+	__u64 userspace_addr;
+	int ret;
+
+	for (done_count = 0; done_count < region->nr_pages; done_count += ret) {
+		pages = region->mreg_pages + done_count;
+		userspace_addr = region->start_uaddr +
+				 done_count * HV_HYP_PAGE_SIZE;
+		nr_pages = min(region->nr_pages - done_count,
+			       MSHV_PIN_PAGES_BATCH_SIZE);
+
+		/*
+		 * Pinning assuming 4k pages works for large pages too.
+		 * All page structs within the large page are returned.
+		 *
+		 * Pin requests are batched because pin_user_pages_fast
+		 * with the FOLL_LONGTERM flag does a large temporary
+		 * allocation of contiguous memory.
+		 */
+		ret = pin_user_pages_fast(userspace_addr, nr_pages,
+					  FOLL_WRITE | FOLL_LONGTERM,
+					  pages);
+		if (ret != nr_pages)
+			goto release_pages;
+	}
+
+	return 0;
+
+release_pages:
+	if (ret > 0)
+		done_count += ret;
+	mshv_region_invalidate_pages(region, 0, done_count);
+	return ret < 0 ? ret : -ENOMEM;
+}
+
+static int mshv_region_chunk_unmap(struct mshv_mem_region *region,
+				   u32 flags,
+				   u64 page_offset, u64 page_count,
+				   bool huge_page)
+{
+	if (huge_page)
+		flags |= HV_UNMAP_GPA_LARGE_PAGE;
+
+	return hv_call_unmap_gpa_pages(region->partition->pt_id,
+				       region->start_gfn + page_offset,
+				       page_count, flags);
+}
+
+static int mshv_region_unmap(struct mshv_mem_region *region)
+{
+	return mshv_region_process_range(region, 0,
+					 0, region->nr_pages,
+					 mshv_region_chunk_unmap);
+}
+
+static void mshv_region_destroy(struct kref *ref)
+{
+	struct mshv_mem_region *region =
+		container_of(ref, struct mshv_mem_region, mreg_refcount);
+	struct mshv_partition *partition = region->partition;
+	int ret;
+
+	if (region->mreg_type == MSHV_REGION_TYPE_MEM_MOVABLE)
+		mshv_region_movable_fini(region);
+
+	if (mshv_partition_encrypted(partition)) {
+		ret = mshv_region_share(region);
+		if (ret) {
+			pt_err(partition,
+			       "Failed to regain access to memory, unpinning user pages will fail and crash the host error: %d\n",
+			       ret);
+			return;
+		}
+	}
+
+	mshv_region_unmap(region);
+
+	mshv_region_invalidate(region);
+
+	vfree(region);
+}
+
+void mshv_region_put(struct mshv_mem_region *region)
+{
+	kref_put(&region->mreg_refcount, mshv_region_destroy);
+}
+
+int mshv_region_get(struct mshv_mem_region *region)
+{
+	return kref_get_unless_zero(&region->mreg_refcount);
+}
+
+/**
+ * mshv_region_range_fault - Handle memory range faults for a given region.
+ * @region: Pointer to the memory region structure.
+ * @page_offset: Offset of the page within the region.
+ * @page_count: Number of pages to handle.
+ *
+ * This function resolves memory faults for a specified range of pages
+ * within a memory region. It uses HMM (Heterogeneous Memory Management)
+ * to fault in the required pages and updates the region's page array.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static int mshv_region_range_fault(struct mshv_mem_region *region,
+				   u64 page_offset, u64 page_count)
+{
+	struct hmm_range range = {
+		.notifier = &region->mreg_mni,
+		.default_flags = HMM_PFN_REQ_FAULT | HMM_PFN_REQ_WRITE,
+	};
+	unsigned long *pfns;
+	int ret;
+	u64 i;
+
+	pfns = kmalloc_array(page_count, sizeof(*pfns), GFP_KERNEL);
+	if (!pfns)
+		return -ENOMEM;
+
+	range.hmm_pfns = pfns;
+	range.start = region->start_uaddr + page_offset * HV_HYP_PAGE_SIZE;
+	range.end = range.start + page_count * HV_HYP_PAGE_SIZE;
+
+again:
+	ret = hmm_range_fault_unlocked_timeout(&range, 0);
+	if (ret)
+		goto out;
+
+	mutex_lock(&region->mreg_mutex);
+
+	if (mmu_interval_read_retry(range.notifier, range.notifier_seq)) {
+		mutex_unlock(&region->mreg_mutex);
+		cond_resched();
+		goto again;
+	}
+
+	for (i = 0; i < page_count; i++)
+		region->mreg_pages[page_offset + i] = hmm_pfn_to_page(pfns[i]);
+
+	ret = mshv_region_remap_pages(region, region->hv_map_flags,
+				      page_offset, page_count);
+
+	mutex_unlock(&region->mreg_mutex);
+out:
+	kfree(pfns);
+	return ret;
+}
+
+bool mshv_region_handle_gfn_fault(struct mshv_mem_region *region, u64 gfn)
+{
+	u64 page_offset, page_count;
+	int ret;
+
+	/* Align the page offset to the nearest MSHV_MAP_FAULT_IN_PAGES. */
+	page_offset = ALIGN_DOWN(gfn - region->start_gfn,
+				 MSHV_MAP_FAULT_IN_PAGES);
+
+	/* Map more pages than requested to reduce the number of faults. */
+	page_count = min(region->nr_pages - page_offset,
+			 MSHV_MAP_FAULT_IN_PAGES);
+
+	ret = mshv_region_range_fault(region, page_offset, page_count);
+
+	WARN_ONCE(ret,
+		  "p%llu: GPA intercept failed: region %#llx-%#llx, gfn %#llx, page_offset %llu, page_count %llu\n",
+		  region->partition->pt_id, region->start_uaddr,
+		  region->start_uaddr + (region->nr_pages << HV_HYP_PAGE_SHIFT),
+		  gfn, page_offset, page_count);
+
+	return !ret;
+}
+
+/**
+ * mshv_region_interval_invalidate - Invalidate a range of memory region
+ * @mni: Pointer to the mmu_interval_notifier structure
+ * @range: Pointer to the mmu_notifier_range structure
+ * @cur_seq: Current sequence number for the interval notifier
+ *
+ * This function invalidates a memory region by remapping its pages with
+ * no access permissions. It locks the region's mutex to ensure thread safety
+ * and updates the sequence number for the interval notifier. If the range
+ * is blockable, it uses a blocking lock; otherwise, it attempts a non-blocking
+ * lock and returns false if unsuccessful.
+ *
+ * NOTE: Failure to invalidate a region is a serious error, as the pages will
+ * be considered freed while they are still mapped by the hypervisor.
+ * Any attempt to access such pages will likely crash the system.
+ *
+ * Return: true if the region was successfully invalidated, false otherwise.
+ */
+static bool mshv_region_interval_invalidate(struct mmu_interval_notifier *mni,
+					    const struct mmu_notifier_range *range,
+					    unsigned long cur_seq)
+{
+	struct mshv_mem_region *region = container_of(mni,
+						      struct mshv_mem_region,
+						      mreg_mni);
+	u64 page_offset, page_count;
+	unsigned long mstart, mend;
+	int ret = -EPERM;
+
+	mstart = max(range->start, region->start_uaddr);
+	mend = min(range->end, region->start_uaddr +
+		   (region->nr_pages << HV_HYP_PAGE_SHIFT));
+
+	page_offset = HVPFN_DOWN(mstart - region->start_uaddr);
+	page_count = HVPFN_DOWN(mend - mstart);
+
+	if (mmu_notifier_range_blockable(range))
+		mutex_lock(&region->mreg_mutex);
+	else if (!mutex_trylock(&region->mreg_mutex))
+		goto out_fail;
+
+	mmu_interval_set_seq(mni, cur_seq);
+
+	ret = mshv_region_remap_pages(region, HV_MAP_GPA_NO_ACCESS,
+				      page_offset, page_count);
+	if (ret)
+		goto out_unlock;
+
+	mshv_region_invalidate_pages(region, page_offset, page_count);
+
+	mutex_unlock(&region->mreg_mutex);
+
+	return true;
+
+out_unlock:
+	mutex_unlock(&region->mreg_mutex);
+out_fail:
+	WARN_ONCE(ret,
+		  "Failed to invalidate region %#llx-%#llx (range %#lx-%#lx, event: %u, pages %#llx-%#llx, mm: %#llx): %d\n",
+		  region->start_uaddr,
+		  region->start_uaddr + (region->nr_pages << HV_HYP_PAGE_SHIFT),
+		  range->start, range->end, range->event,
+		  page_offset, page_offset + page_count - 1, (u64)range->mm, ret);
+	return false;
+}
+
+static const struct mmu_interval_notifier_ops mshv_region_mni_ops = {
+	.invalidate = mshv_region_interval_invalidate,
+};
+
+void mshv_region_movable_fini(struct mshv_mem_region *region)
+{
+	mmu_interval_notifier_remove(&region->mreg_mni);
+}
+
+bool mshv_region_movable_init(struct mshv_mem_region *region)
+{
+	int ret;
+
+	ret = mmu_interval_notifier_insert(&region->mreg_mni, current->mm,
+					   region->start_uaddr,
+					   region->nr_pages << HV_HYP_PAGE_SHIFT,
+					   &mshv_region_mni_ops);
+	if (ret)
+		return false;
+
+	mutex_init(&region->mreg_mutex);
+
+	return true;
+}
diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
new file mode 100644
index 000000000..1f086dcb7
--- /dev/null
+++ b/drivers/hv/mshv_root.h
@@ -0,0 +1,381 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ */
+
+#ifndef _MSHV_ROOT_H_
+#define _MSHV_ROOT_H_
+
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/semaphore.h>
+#include <linux/sched.h>
+#include <linux/srcu.h>
+#include <linux/wait.h>
+#include <linux/hashtable.h>
+#include <linux/dev_printk.h>
+#include <linux/build_bug.h>
+#include <linux/mmu_notifier.h>
+#include <uapi/linux/mshv.h>
+#include "mshv_trace.h"
+
+/*
+ * Hypervisor must be between these version numbers (inclusive)
+ * to guarantee compatibility
+ */
+#define MSHV_HV_MIN_VERSION		(27744)
+#define MSHV_HV_MAX_VERSION		(27751)
+
+static_assert(HV_HYP_PAGE_SIZE == MSHV_HV_PAGE_SIZE);
+
+#define MSHV_MAX_VPS			256
+
+#define MSHV_PARTITIONS_HASH_BITS	9
+
+#define MSHV_PIN_PAGES_BATCH_SIZE	(0x10000000ULL / HV_HYP_PAGE_SIZE)
+
+struct mshv_vp {
+	u32 vp_index;
+	struct mshv_partition *vp_partition;
+	struct mutex vp_mutex;
+	struct hv_vp_register_page *vp_register_page;
+	struct hv_message *vp_intercept_msg_page;
+	void *vp_ghcb_page;
+	struct hv_stats_page *vp_stats_pages[2];
+	struct {
+		atomic64_t vp_signaled_count;
+		struct {
+			u64 intercept_suspend: 1;
+			u64 root_sched_blocked: 1; /* root scheduler only */
+			u64 root_sched_dispatched: 1; /* root scheduler only */
+			u64 reserved: 61;
+		} flags;
+		unsigned int kicked_by_hv;
+		wait_queue_head_t vp_suspend_queue;
+	} run;
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	struct dentry *vp_stats_dentry;
+#endif
+};
+
+#define vp_fmt(fmt) "p%lluvp%u: " fmt
+#define vp_devprintk(level, v, fmt, ...) \
+do { \
+	const struct mshv_vp *__vp = (v); \
+	const struct mshv_partition *__pt = __vp->vp_partition; \
+	dev_##level(__pt->pt_module_dev, vp_fmt(fmt), __pt->pt_id, \
+		    __vp->vp_index, ##__VA_ARGS__); \
+} while (0)
+#define vp_emerg(v, fmt, ...)	vp_devprintk(emerg, v, fmt, ##__VA_ARGS__)
+#define vp_crit(v, fmt, ...)	vp_devprintk(crit, v, fmt, ##__VA_ARGS__)
+#define vp_alert(v, fmt, ...)	vp_devprintk(alert, v, fmt, ##__VA_ARGS__)
+#define vp_err(v, fmt, ...)	vp_devprintk(err, v, fmt, ##__VA_ARGS__)
+#define vp_warn(v, fmt, ...)	vp_devprintk(warn, v, fmt, ##__VA_ARGS__)
+#define vp_notice(v, fmt, ...)	vp_devprintk(notice, v, fmt, ##__VA_ARGS__)
+#define vp_info(v, fmt, ...)	vp_devprintk(info, v, fmt, ##__VA_ARGS__)
+#define vp_dbg(v, fmt, ...)	vp_devprintk(dbg, v, fmt, ##__VA_ARGS__)
+
+enum mshv_region_type {
+	MSHV_REGION_TYPE_MEM_PINNED,
+	MSHV_REGION_TYPE_MEM_MOVABLE,
+	MSHV_REGION_TYPE_MMIO
+};
+
+struct mshv_mem_region {
+	struct hlist_node hnode;
+	struct kref mreg_refcount;
+	u64 nr_pages;
+	u64 start_gfn;
+	u64 start_uaddr;
+	u32 hv_map_flags;
+	struct mshv_partition *partition;
+	enum mshv_region_type mreg_type;
+	struct mmu_interval_notifier mreg_mni;
+	struct mutex mreg_mutex;	/* protects region pages remapping */
+	struct page *mreg_pages[];
+};
+
+struct mshv_irq_ack_notifier {
+	struct hlist_node link;
+	unsigned int irq_ack_gsi;
+	void (*irq_acked)(struct mshv_irq_ack_notifier *mian);
+};
+
+struct mshv_partition {
+	struct device *pt_module_dev;
+
+	struct hlist_node pt_hnode;
+	u64 pt_id;
+	refcount_t pt_ref_count;
+	struct mutex pt_mutex;
+
+	spinlock_t pt_mem_regions_lock;
+	struct hlist_head pt_mem_regions; // not ordered
+
+	u32 pt_vp_count;
+	struct mshv_vp *pt_vp_array[MSHV_MAX_VPS];
+
+	struct mutex pt_irq_lock;
+	struct srcu_struct pt_irq_srcu;
+	struct hlist_head irq_ack_notifier_list;
+
+	struct hlist_head pt_devices;
+
+	/*
+	 * MSHV does not support more than one async hypercall in flight
+	 * for a single partition. Thus, it is okay to define per partition
+	 * async hypercall status.
+	 */
+	struct completion async_hypercall;
+	u64 async_hypercall_status;
+
+	spinlock_t	  pt_irqfds_lock;
+	struct hlist_head pt_irqfds_list;
+	struct mutex	  irqfds_resampler_lock;
+	struct hlist_head irqfds_resampler_list;
+
+	struct hlist_head ioeventfds_list;
+
+	struct mshv_girq_routing_table __rcu *pt_girq_tbl;
+	u64 isolation_type;
+	bool import_completed;
+	bool pt_initialized;
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	struct dentry *pt_stats_dentry;
+	struct dentry *pt_vp_dentry;
+#endif
+};
+
+#define pt_fmt(fmt) "p%llu: " fmt
+#define pt_devprintk(level, p, fmt, ...) \
+do { \
+	const struct mshv_partition *__pt = (p); \
+	dev_##level(__pt->pt_module_dev, pt_fmt(fmt), __pt->pt_id, \
+		    ##__VA_ARGS__); \
+} while (0)
+#define pt_emerg(p, fmt, ...)	pt_devprintk(emerg, p, fmt, ##__VA_ARGS__)
+#define pt_crit(p, fmt, ...)	pt_devprintk(crit, p, fmt, ##__VA_ARGS__)
+#define pt_alert(p, fmt, ...)	pt_devprintk(alert, p, fmt, ##__VA_ARGS__)
+#define pt_err(p, fmt, ...)	pt_devprintk(err, p, fmt, ##__VA_ARGS__)
+#define pt_warn(p, fmt, ...)	pt_devprintk(warn, p, fmt, ##__VA_ARGS__)
+#define pt_notice(p, fmt, ...)	pt_devprintk(notice, p, fmt, ##__VA_ARGS__)
+#define pt_info(p, fmt, ...)	pt_devprintk(info, p, fmt, ##__VA_ARGS__)
+#define pt_dbg(p, fmt, ...)	pt_devprintk(dbg, p, fmt, ##__VA_ARGS__)
+
+struct mshv_lapic_irq {
+	u32 lapic_vector;
+	u64 lapic_apic_id;
+	union hv_interrupt_control lapic_control;
+};
+
+#define MSHV_MAX_GUEST_IRQS		4096
+
+/* representation of one guest irq entry, either msi or legacy */
+struct mshv_guest_irq_ent {
+	u32 girq_entry_valid;	/* vfio looks at this */
+	u32 guest_irq_num;	/* a unique number for each irq */
+	u32 girq_addr_lo;	/* guest irq msi address info */
+	u32 girq_addr_hi;
+	u32 girq_irq_data;	/* idt vector in some cases */
+};
+
+struct mshv_girq_routing_table {
+	u32 num_rt_entries;
+	struct mshv_guest_irq_ent mshv_girq_info_tbl[];
+};
+
+struct hv_synic_pages {
+	struct hv_message_page *hyp_synic_message_page;
+	struct hv_synic_event_flags_page *synic_event_flags_page;
+	struct hv_synic_event_ring_page *synic_event_ring_page;
+};
+
+struct mshv_root {
+	spinlock_t pt_ht_lock;
+	DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS);
+	struct hv_partition_property_vmm_capabilities vmm_caps;
+};
+
+/*
+ * Callback for doorbell events.
+ * NOTE: This is called in interrupt context. Callback
+ * should defer slow and sleeping logic to later.
+ */
+typedef void (*doorbell_cb_t) (int doorbell_id, void *);
+
+/*
+ * port table information
+ */
+struct port_table_info {
+	struct rcu_head portbl_rcu;
+	enum hv_port_type hv_port_type;
+	union {
+		struct {
+			u64 reserved[2];
+		} hv_port_message;
+		struct {
+			u64 reserved[2];
+		} hv_port_event;
+		struct {
+			u64 reserved[2];
+		} hv_port_monitor;
+		struct {
+			doorbell_cb_t doorbell_cb;
+			void *data;
+		} hv_port_doorbell;
+	};
+};
+
+int mshv_update_routing_table(struct mshv_partition *partition,
+			      const struct mshv_user_irq_entry *entries,
+			      unsigned int numents);
+void mshv_free_routing_table(struct mshv_partition *partition);
+
+struct mshv_guest_irq_ent mshv_ret_girq_entry(struct mshv_partition *partition,
+					      u32 irq_num);
+
+void mshv_copy_girq_info(struct mshv_guest_irq_ent *src_irq,
+			 struct mshv_lapic_irq *dest_irq);
+
+void mshv_irqfd_routing_update(struct mshv_partition *partition);
+
+void mshv_port_table_fini(void);
+int mshv_portid_alloc(struct port_table_info *info);
+int mshv_portid_lookup(int port_id, struct port_table_info *info);
+void mshv_portid_free(int port_id);
+
+int mshv_register_doorbell(u64 partition_id, doorbell_cb_t doorbell_cb,
+			   void *data, u64 gpa, u64 val, u64 flags);
+void mshv_unregister_doorbell(u64 partition_id, int doorbell_portid);
+
+void mshv_isr(void);
+int mshv_synic_init(struct device *dev);
+void mshv_synic_exit(void);
+
+static inline bool mshv_partition_encrypted(struct mshv_partition *partition)
+{
+	return partition->isolation_type == HV_PARTITION_ISOLATION_TYPE_SNP;
+}
+
+struct mshv_partition *mshv_partition_get(struct mshv_partition *partition);
+void mshv_partition_put(struct mshv_partition *partition);
+struct mshv_partition *mshv_partition_find(u64 partition_id) __must_hold(RCU);
+
+static inline bool is_l1vh_parent(u64 partition_id)
+{
+	return hv_l1vh_partition() && (partition_id == HV_PARTITION_ID_SELF);
+}
+
+int mshv_vp_stats_map(u64 partition_id, u32 vp_index,
+		      struct hv_stats_page **stats_pages);
+void mshv_vp_stats_unmap(u64 partition_id, u32 vp_index,
+			 struct hv_stats_page **stats_pages);
+
+/* hypercalls */
+
+int hv_call_withdraw_memory(u64 count, int node, u64 partition_id);
+int hv_call_create_partition(u64 flags,
+			     struct hv_partition_creation_properties creation_properties,
+			     union hv_partition_isolation_properties isolation_properties,
+			     u64 *partition_id);
+int hv_call_initialize_partition(u64 partition_id);
+int hv_call_finalize_partition(u64 partition_id);
+int hv_call_delete_partition(u64 partition_id);
+int hv_call_map_mmio_pages(u64 partition_id, u64 gfn, u64 mmio_spa, u64 numpgs);
+int hv_call_map_gpa_pages(u64 partition_id, u64 gpa_target, u64 page_count,
+			  u32 flags, struct page **pages);
+int hv_call_unmap_gpa_pages(u64 partition_id, u64 gpa_target, u64 page_count,
+			    u32 flags);
+int hv_call_delete_vp(u64 partition_id, u32 vp_index);
+int hv_call_assert_virtual_interrupt(u64 partition_id, u32 vector,
+				     u64 dest_addr,
+				     union hv_interrupt_control control);
+int hv_call_clear_virtual_interrupt(u64 partition_id);
+int hv_call_get_gpa_access_states(u64 partition_id, u32 count, u64 gpa_base_pfn,
+				  union hv_gpa_page_access_state_flags state_flags,
+				  int *written_total,
+				  union hv_gpa_page_access_state *states);
+int hv_call_get_vp_state(u32 vp_index, u64 partition_id,
+			 struct hv_vp_state_data state_data,
+			 /* Choose between pages and ret_output */
+			 u64 page_count, struct page **pages,
+			 union hv_output_get_vp_state *ret_output);
+int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
+			 /* Choose between pages and bytes */
+			 struct hv_vp_state_data state_data, u64 page_count,
+			 struct page **pages, u32 num_bytes, u8 *bytes);
+int hv_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			 union hv_input_vtl input_vtl,
+			 struct page **state_page);
+int hv_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			   struct page *state_page,
+			   union hv_input_vtl input_vtl);
+int hv_call_create_port(u64 port_partition_id, union hv_port_id port_id,
+			u64 connection_partition_id, struct hv_port_info *port_info,
+			u8 port_vtl, u8 min_connection_vtl, int node);
+int hv_call_delete_port(u64 port_partition_id, union hv_port_id port_id);
+int hv_call_connect_port(u64 port_partition_id, union hv_port_id port_id,
+			 u64 connection_partition_id,
+			 union hv_connection_id connection_id,
+			 struct hv_connection_info *connection_info,
+			 u8 connection_vtl, int node);
+int hv_call_disconnect_port(u64 connection_partition_id,
+			    union hv_connection_id connection_id);
+int hv_call_notify_port_ring_empty(u32 sint_index);
+int hv_map_stats_page(enum hv_stats_object_type type,
+		      const union hv_stats_object_identity *identity,
+		      struct hv_stats_page **addr);
+int hv_unmap_stats_page(enum hv_stats_object_type type,
+			struct hv_stats_page *page_addr,
+			const union hv_stats_object_identity *identity);
+int hv_call_modify_spa_host_access(u64 partition_id, struct page **pages,
+				   u64 page_struct_count, u32 host_access,
+				   u32 flags, u8 acquire);
+int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code, u64 arg,
+				      void *property_value, size_t property_value_sz);
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+int __init mshv_debugfs_init(void);
+void mshv_debugfs_exit(void);
+
+int mshv_debugfs_partition_create(struct mshv_partition *partition);
+void mshv_debugfs_partition_remove(struct mshv_partition *partition);
+int mshv_debugfs_vp_create(struct mshv_vp *vp);
+void mshv_debugfs_vp_remove(struct mshv_vp *vp);
+#else
+static inline int __init mshv_debugfs_init(void)
+{
+	return 0;
+}
+static inline void mshv_debugfs_exit(void) { }
+
+static inline int mshv_debugfs_partition_create(struct mshv_partition *partition)
+{
+	return 0;
+}
+static inline void mshv_debugfs_partition_remove(struct mshv_partition *partition) { }
+static inline int mshv_debugfs_vp_create(struct mshv_vp *vp)
+{
+	return 0;
+}
+static inline void mshv_debugfs_vp_remove(struct mshv_vp *vp) { }
+#endif
+
+extern struct mshv_root mshv_root;
+extern enum hv_scheduler_type hv_scheduler_type;
+extern u8 * __percpu *hv_synic_eventring_tail;
+
+struct mshv_mem_region *mshv_region_create(u64 guest_pfn, u64 nr_pages,
+					   u64 uaddr, u32 flags);
+int mshv_region_share(struct mshv_mem_region *region);
+int mshv_region_unshare(struct mshv_mem_region *region);
+int mshv_region_map(struct mshv_mem_region *region);
+void mshv_region_invalidate(struct mshv_mem_region *region);
+int mshv_region_pin(struct mshv_mem_region *region);
+void mshv_region_put(struct mshv_mem_region *region);
+int mshv_region_get(struct mshv_mem_region *region);
+bool mshv_region_handle_gfn_fault(struct mshv_mem_region *region, u64 gfn);
+void mshv_region_movable_fini(struct mshv_mem_region *region);
+bool mshv_region_movable_init(struct mshv_mem_region *region);
+
+#endif /* _MSHV_ROOT_H_ */
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
new file mode 100644
index 000000000..cb55d4d4b
--- /dev/null
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -0,0 +1,1074 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ *
+ * Hypercall helper functions used by the mshv_root module.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <asm/mshyperv.h>
+
+#include "mshv_root.h"
+
+/* Determined empirically */
+#define HV_INIT_PARTITION_DEPOSIT_PAGES 208
+#define HV_MAP_GPA_DEPOSIT_PAGES	256
+#define HV_UMAP_GPA_PAGES		512
+
+#define HV_PAGE_COUNT_2M_ALIGNED(pg_count) (!((pg_count) & (0x200 - 1)))
+
+#define HV_WITHDRAW_BATCH_SIZE	(HV_HYP_PAGE_SIZE / sizeof(u64))
+#define HV_MAP_GPA_BATCH_SIZE	\
+	((HV_HYP_PAGE_SIZE - sizeof(struct hv_input_map_gpa_pages)) \
+		/ sizeof(u64))
+#define HV_GET_VP_STATE_BATCH_SIZE	\
+	((HV_HYP_PAGE_SIZE - sizeof(struct hv_input_get_vp_state)) \
+		/ sizeof(u64))
+#define HV_SET_VP_STATE_BATCH_SIZE	\
+	((HV_HYP_PAGE_SIZE - sizeof(struct hv_input_set_vp_state)) \
+		/ sizeof(u64))
+#define HV_GET_GPA_ACCESS_STATES_BATCH_SIZE	\
+	((HV_HYP_PAGE_SIZE - sizeof(union hv_gpa_page_access_state)) \
+		/ sizeof(union hv_gpa_page_access_state))
+#define HV_MODIFY_SPARSE_SPA_PAGE_HOST_ACCESS_MAX_PAGE_COUNT		       \
+	((HV_HYP_PAGE_SIZE -						       \
+	  sizeof(struct hv_input_modify_sparse_spa_page_host_access)) /        \
+	 sizeof(u64))
+
+int hv_call_withdraw_memory(u64 count, int node, u64 partition_id)
+{
+	struct hv_input_withdraw_memory *input_page;
+	struct hv_output_withdraw_memory *output_page;
+	struct page *page;
+	u16 completed;
+	u64 status, withdrawn = 0;
+	int i;
+	unsigned long flags;
+
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+	output_page = page_address(page);
+
+	while (withdrawn < count) {
+		local_irq_save(flags);
+
+		input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		memset(input_page, 0, sizeof(*input_page));
+		input_page->partition_id = partition_id;
+		status = hv_do_rep_hypercall(HVCALL_WITHDRAW_MEMORY,
+					     min(count - withdrawn, HV_WITHDRAW_BATCH_SIZE),
+					     0, input_page, output_page);
+
+		local_irq_restore(flags);
+
+		completed = hv_repcomp(status);
+
+		for (i = 0; i < completed; i++)
+			__free_page(pfn_to_page(output_page->gpa_page_list[i]));
+
+		if (!hv_result_success(status)) {
+			if (hv_result(status) == HV_STATUS_NO_RESOURCES)
+				status = HV_STATUS_SUCCESS;
+			break;
+		}
+
+		withdrawn += completed;
+	}
+	free_page((unsigned long)output_page);
+
+	trace_mshv_hvcall_withdraw_memory(partition_id, withdrawn, status);
+
+	return hv_result_to_errno(status);
+}
+
+int hv_call_create_partition(u64 flags,
+			     struct hv_partition_creation_properties creation_properties,
+			     union hv_partition_isolation_properties isolation_properties,
+			     u64 *partition_id)
+{
+	struct hv_input_create_partition *input;
+	struct hv_output_create_partition *output;
+	u64 status;
+	int ret;
+	unsigned long irq_flags;
+
+	do {
+		local_irq_save(irq_flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+		memset(input, 0, sizeof(*input));
+		input->flags = flags;
+		input->compatibility_version = HV_COMPATIBILITY_21_H2;
+
+		memcpy(&input->partition_creation_properties, &creation_properties,
+		       sizeof(creation_properties));
+
+		memcpy(&input->isolation_properties, &isolation_properties,
+		       sizeof(isolation_properties));
+
+		status = hv_do_hypercall(HVCALL_CREATE_PARTITION,
+					 input, output);
+
+		if (!hv_result_needs_memory(status)) {
+			if (hv_result_success(status))
+				*partition_id = output->partition_id;
+			local_irq_restore(irq_flags);
+			ret = hv_result_to_errno(status);
+			break;
+		}
+		local_irq_restore(irq_flags);
+		ret = hv_deposit_memory(hv_current_partition_id, status);
+	} while (!ret);
+
+	trace_mshv_hvcall_create_partition(flags, ret ? ret : *partition_id);
+
+	return ret;
+}
+
+int hv_call_initialize_partition(u64 partition_id)
+{
+	struct hv_input_initialize_partition input;
+	u64 status;
+	int ret;
+
+	input.partition_id = partition_id;
+
+	ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id,
+				    HV_INIT_PARTITION_DEPOSIT_PAGES);
+	if (ret)
+		return ret;
+
+	do {
+		status = hv_do_fast_hypercall8(HVCALL_INITIALIZE_PARTITION,
+					       *(u64 *)&input);
+
+		if (!hv_result_needs_memory(status)) {
+			ret = hv_result_to_errno(status);
+			break;
+		}
+		ret = hv_deposit_memory(partition_id, status);
+	} while (!ret);
+
+	trace_mshv_hvcall_initialize_partition(partition_id, status);
+
+	return ret;
+}
+
+int hv_call_finalize_partition(u64 partition_id)
+{
+	struct hv_input_finalize_partition input;
+	u64 status;
+
+	input.partition_id = partition_id;
+	status = hv_do_fast_hypercall8(HVCALL_FINALIZE_PARTITION,
+				       *(u64 *)&input);
+
+	trace_mshv_hvcall_finalize_partition(partition_id, status);
+
+	return hv_result_to_errno(status);
+}
+
+int hv_call_delete_partition(u64 partition_id)
+{
+	struct hv_input_delete_partition input;
+	u64 status;
+
+	input.partition_id = partition_id;
+	status = hv_do_fast_hypercall8(HVCALL_DELETE_PARTITION, *(u64 *)&input);
+
+	trace_mshv_hvcall_delete_partition(partition_id, status);
+
+	return hv_result_to_errno(status);
+}
+
+/* Ask the hypervisor to map guest ram pages or the guest mmio space */
+static int hv_do_map_gpa_hcall(u64 partition_id, u64 gfn, u64 page_struct_count,
+			       u32 flags, struct page **pages, u64 mmio_spa)
+{
+	struct hv_input_map_gpa_pages *input_page;
+	u64 status, *pfnlist;
+	unsigned long irq_flags, large_shift = 0;
+	int ret = 0, done = 0;
+	u64 page_count = page_struct_count;
+
+	if (page_count == 0 || (pages && mmio_spa))
+		return -EINVAL;
+
+	if (flags & HV_MAP_GPA_LARGE_PAGE) {
+		if (mmio_spa)
+			return -EINVAL;
+
+		if (!HV_PAGE_COUNT_2M_ALIGNED(page_count))
+			return -EINVAL;
+
+		large_shift = HV_HYP_LARGE_PAGE_SHIFT - HV_HYP_PAGE_SHIFT;
+		page_count >>= large_shift;
+	}
+
+	while (done < page_count) {
+		ulong i, completed, remain = page_count - done;
+		int rep_count = min(remain, HV_MAP_GPA_BATCH_SIZE);
+
+		local_irq_save(irq_flags);
+		input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		input_page->target_partition_id = partition_id;
+		input_page->target_gpa_base = gfn + (done << large_shift);
+		input_page->map_flags = flags;
+		pfnlist = input_page->source_gpa_page_list;
+
+		for (i = 0; i < rep_count; i++)
+			if (flags & HV_MAP_GPA_NO_ACCESS) {
+				pfnlist[i] = 0;
+			} else if (pages) {
+				u64 index = (done + i) << large_shift;
+
+				if (index >= page_struct_count) {
+					ret = -EINVAL;
+					break;
+				}
+				pfnlist[i] = page_to_pfn(pages[index]);
+			} else {
+				pfnlist[i] = mmio_spa + done + i;
+			}
+		if (ret)
+			break;
+
+		status = hv_do_rep_hypercall(HVCALL_MAP_GPA_PAGES, rep_count, 0,
+					     input_page, NULL);
+		local_irq_restore(irq_flags);
+
+		completed = hv_repcomp(status);
+
+		if (hv_result_needs_memory(status)) {
+			ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id,
+						    HV_MAP_GPA_DEPOSIT_PAGES);
+			if (ret)
+				break;
+
+		} else if (!hv_result_success(status)) {
+			ret = hv_result_to_errno(status);
+			break;
+		}
+
+		done += completed;
+	}
+
+	if (ret && done) {
+		u32 unmap_flags = 0;
+
+		if (flags & HV_MAP_GPA_LARGE_PAGE)
+			unmap_flags |= HV_UNMAP_GPA_LARGE_PAGE;
+		hv_call_unmap_gpa_pages(partition_id, gfn, done, unmap_flags);
+	}
+
+	return ret;
+}
+
+/* Ask the hypervisor to map guest ram pages */
+int hv_call_map_gpa_pages(u64 partition_id, u64 gpa_target, u64 page_count,
+			  u32 flags, struct page **pages)
+{
+	return hv_do_map_gpa_hcall(partition_id, gpa_target, page_count,
+				   flags, pages, 0);
+}
+
+/* Ask the hypervisor to map guest mmio space */
+int hv_call_map_mmio_pages(u64 partition_id, u64 gfn, u64 mmio_spa, u64 numpgs)
+{
+	int i;
+	u32 flags = HV_MAP_GPA_READABLE | HV_MAP_GPA_WRITABLE |
+		    HV_MAP_GPA_NOT_CACHED;
+
+	for (i = 0; i < numpgs; i++)
+		if (page_is_ram(mmio_spa + i))
+			return -EINVAL;
+
+	return hv_do_map_gpa_hcall(partition_id, gfn, numpgs, flags, NULL,
+				   mmio_spa);
+}
+
+int hv_call_unmap_gpa_pages(u64 partition_id, u64 gfn, u64 page_count_4k,
+			    u32 flags)
+{
+	struct hv_input_unmap_gpa_pages *input_page;
+	u64 status, page_count = page_count_4k;
+	unsigned long irq_flags, large_shift = 0;
+	int ret = 0, done = 0;
+
+	if (page_count == 0)
+		return -EINVAL;
+
+	if (flags & HV_UNMAP_GPA_LARGE_PAGE) {
+		if (!HV_PAGE_COUNT_2M_ALIGNED(page_count))
+			return -EINVAL;
+
+		large_shift = HV_HYP_LARGE_PAGE_SHIFT - HV_HYP_PAGE_SHIFT;
+		page_count >>= large_shift;
+	}
+
+	while (done < page_count) {
+		ulong completed, remain = page_count - done;
+		int rep_count = min(remain, HV_UMAP_GPA_PAGES);
+
+		local_irq_save(irq_flags);
+		input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		input_page->target_partition_id = partition_id;
+		input_page->target_gpa_base = gfn + (done << large_shift);
+		input_page->unmap_flags = flags;
+		status = hv_do_rep_hypercall(HVCALL_UNMAP_GPA_PAGES, rep_count,
+					     0, input_page, NULL);
+		local_irq_restore(irq_flags);
+
+		completed = hv_repcomp(status);
+		if (!hv_result_success(status)) {
+			ret = hv_result_to_errno(status);
+			break;
+		}
+
+		done += completed;
+	}
+
+	return ret;
+}
+
+int hv_call_get_gpa_access_states(u64 partition_id, u32 count, u64 gpa_base_pfn,
+				  union hv_gpa_page_access_state_flags state_flags,
+				  int *written_total,
+				  union hv_gpa_page_access_state *states)
+{
+	struct hv_input_get_gpa_pages_access_state *input_page;
+	union hv_gpa_page_access_state *output_page;
+	int completed = 0;
+	unsigned long remaining = count;
+	int rep_count, i;
+	u64 status = 0;
+	unsigned long flags;
+
+	*written_total = 0;
+	while (remaining) {
+		local_irq_save(flags);
+		input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+		input_page->partition_id = partition_id;
+		input_page->hv_gpa_page_number = gpa_base_pfn + *written_total;
+		input_page->flags = state_flags;
+		rep_count = min(remaining, HV_GET_GPA_ACCESS_STATES_BATCH_SIZE);
+
+		status = hv_do_rep_hypercall(HVCALL_GET_GPA_PAGES_ACCESS_STATES, rep_count,
+					     0, input_page, output_page);
+		if (!hv_result_success(status)) {
+			local_irq_restore(flags);
+			break;
+		}
+		completed = hv_repcomp(status);
+		for (i = 0; i < completed; ++i)
+			states[i].as_uint8 = output_page[i].as_uint8;
+
+		local_irq_restore(flags);
+		states += completed;
+		*written_total += completed;
+		remaining -= completed;
+	}
+
+	return hv_result_to_errno(status);
+}
+
+int hv_call_assert_virtual_interrupt(u64 partition_id, u32 vector,
+				     u64 dest_addr,
+				     union hv_interrupt_control control)
+{
+	struct hv_input_assert_virtual_interrupt *input;
+	unsigned long flags;
+	u64 status;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(input, 0, sizeof(*input));
+	input->partition_id = partition_id;
+	input->vector = vector;
+	/*
+	 * NOTE: dest_addr only needs to be provided while asserting an
+	 * interrupt on x86 platform
+	 */
+#if IS_ENABLED(CONFIG_X86)
+	input->dest_addr = dest_addr;
+#endif
+	input->control = control;
+	status = hv_do_hypercall(HVCALL_ASSERT_VIRTUAL_INTERRUPT, input, NULL);
+	local_irq_restore(flags);
+
+	return hv_result_to_errno(status);
+}
+
+int hv_call_delete_vp(u64 partition_id, u32 vp_index)
+{
+	union hv_input_delete_vp input = {};
+	u64 status;
+
+	input.partition_id = partition_id;
+	input.vp_index = vp_index;
+
+	status = hv_do_fast_hypercall16(HVCALL_DELETE_VP,
+					input.as_uint64[0], input.as_uint64[1]);
+
+	return hv_result_to_errno(status);
+}
+EXPORT_SYMBOL_GPL(hv_call_delete_vp);
+
+int hv_call_get_vp_state(u32 vp_index, u64 partition_id,
+			 struct hv_vp_state_data state_data,
+			 /* Choose between pages and ret_output */
+			 u64 page_count, struct page **pages,
+			 union hv_output_get_vp_state *ret_output)
+{
+	struct hv_input_get_vp_state *input;
+	union hv_output_get_vp_state *output;
+	u64 status;
+	int i;
+	u64 control;
+	unsigned long flags;
+	int ret = 0;
+
+	if (page_count > HV_GET_VP_STATE_BATCH_SIZE)
+		return -EINVAL;
+
+	if (!page_count && !ret_output)
+		return -EINVAL;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+		memset(input, 0, sizeof(*input));
+		memset(output, 0, sizeof(*output));
+
+		input->partition_id = partition_id;
+		input->vp_index = vp_index;
+		input->state_data = state_data;
+		for (i = 0; i < page_count; i++)
+			input->output_data_pfns[i] = page_to_pfn(pages[i]);
+
+		control = (HVCALL_GET_VP_STATE) |
+			  (page_count << HV_HYPERCALL_VARHEAD_OFFSET);
+
+		status = hv_do_hypercall(control, input, output);
+
+		if (!hv_result_needs_memory(status)) {
+			if (hv_result_success(status) && ret_output)
+				memcpy(ret_output, output, sizeof(*output));
+
+			local_irq_restore(flags);
+			ret = hv_result_to_errno(status);
+			break;
+		}
+		local_irq_restore(flags);
+
+		ret = hv_deposit_memory(partition_id, status);
+	} while (!ret);
+
+	return ret;
+}
+
+int hv_call_set_vp_state(u32 vp_index, u64 partition_id,
+			 /* Choose between pages and bytes */
+			 struct hv_vp_state_data state_data, u64 page_count,
+			 struct page **pages, u32 num_bytes, u8 *bytes)
+{
+	struct hv_input_set_vp_state *input;
+	u64 status;
+	int i;
+	u64 control;
+	unsigned long flags;
+	int ret = 0;
+	u16 varhead_sz;
+
+	if (page_count > HV_SET_VP_STATE_BATCH_SIZE)
+		return -EINVAL;
+	if (sizeof(*input) + num_bytes > HV_HYP_PAGE_SIZE)
+		return -EINVAL;
+
+	if (num_bytes)
+		/* round up to 8 and divide by 8 */
+		varhead_sz = (num_bytes + 7) >> 3;
+	else if (page_count)
+		varhead_sz = page_count;
+	else
+		return -EINVAL;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		memset(input, 0, sizeof(*input));
+
+		input->partition_id = partition_id;
+		input->vp_index = vp_index;
+		input->state_data = state_data;
+		if (num_bytes) {
+			memcpy((u8 *)input->data, bytes, num_bytes);
+		} else {
+			for (i = 0; i < page_count; i++)
+				input->data[i].pfns = page_to_pfn(pages[i]);
+		}
+
+		control = (HVCALL_SET_VP_STATE) |
+			  (varhead_sz << HV_HYPERCALL_VARHEAD_OFFSET);
+
+		status = hv_do_hypercall(control, input, NULL);
+
+		if (!hv_result_needs_memory(status)) {
+			local_irq_restore(flags);
+			ret = hv_result_to_errno(status);
+			break;
+		}
+		local_irq_restore(flags);
+
+		ret = hv_deposit_memory(partition_id, status);
+	} while (!ret);
+
+	return ret;
+}
+
+static int hv_call_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+				     union hv_input_vtl input_vtl,
+				     struct page **state_page)
+{
+	struct hv_input_map_vp_state_page *input;
+	struct hv_output_map_vp_state_page *output;
+	u64 status;
+	int ret;
+	unsigned long flags;
+
+	do {
+		local_irq_save(flags);
+
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+		memset(input, 0, sizeof(*input));
+		input->partition_id = partition_id;
+		input->vp_index = vp_index;
+		input->type = type;
+		input->input_vtl = input_vtl;
+
+		if (*state_page) {
+			input->flags.map_location_provided = 1;
+			input->requested_map_location =
+				page_to_pfn(*state_page);
+		}
+
+		status = hv_do_hypercall(HVCALL_MAP_VP_STATE_PAGE, input,
+					 output);
+
+		if (!hv_result_needs_memory(status)) {
+			if (hv_result_success(status))
+				*state_page = pfn_to_page(output->map_location);
+			local_irq_restore(flags);
+			ret = hv_result_to_errno(status);
+			break;
+		}
+
+		local_irq_restore(flags);
+
+		ret = hv_deposit_memory(partition_id, status);
+	} while (!ret);
+
+	trace_mshv_hvcall_map_vp_state_page(partition_id, vp_index,
+					    type, status);
+
+	return ret;
+}
+
+static bool mshv_use_overlay_gpfn(void)
+{
+	return hv_l1vh_partition() &&
+	       mshv_root.vmm_caps.vmm_can_provide_overlay_gpfn;
+}
+
+int hv_map_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			 union hv_input_vtl input_vtl,
+			 struct page **state_page)
+{
+	int ret = 0;
+	struct page *allocated_page = NULL;
+
+	if (mshv_use_overlay_gpfn()) {
+		allocated_page = alloc_page(GFP_KERNEL);
+		if (!allocated_page)
+			return -ENOMEM;
+		*state_page = allocated_page;
+	} else {
+		*state_page = NULL;
+	}
+
+	ret = hv_call_map_vp_state_page(partition_id, vp_index, type, input_vtl,
+					state_page);
+
+	if (ret && allocated_page) {
+		__free_page(allocated_page);
+		*state_page = NULL;
+	}
+
+	return ret;
+}
+
+static int hv_call_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+				       union hv_input_vtl input_vtl)
+{
+	unsigned long flags;
+	u64 status;
+	struct hv_input_unmap_vp_state_page *input;
+
+	local_irq_save(flags);
+
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	memset(input, 0, sizeof(*input));
+
+	input->partition_id = partition_id;
+	input->vp_index = vp_index;
+	input->type = type;
+	input->input_vtl = input_vtl;
+
+	status = hv_do_hypercall(HVCALL_UNMAP_VP_STATE_PAGE, input, NULL);
+
+	local_irq_restore(flags);
+
+	return hv_result_to_errno(status);
+}
+
+int hv_unmap_vp_state_page(u64 partition_id, u32 vp_index, u32 type,
+			   struct page *state_page, union hv_input_vtl input_vtl)
+{
+	int ret = hv_call_unmap_vp_state_page(partition_id, vp_index, type, input_vtl);
+
+	if (mshv_use_overlay_gpfn() && state_page)
+		__free_page(state_page);
+
+	return ret;
+}
+
+int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code,
+				      u64 arg, void *property_value,
+				      size_t property_value_sz)
+{
+	u64 status;
+	unsigned long flags;
+	struct hv_input_get_partition_property_ex *input;
+	struct hv_output_get_partition_property_ex *output;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	memset(input, 0, sizeof(*input));
+	input->partition_id = partition_id;
+	input->property_code = property_code;
+	input->arg = arg;
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_PROPERTY_EX, input, output);
+
+	if (!hv_result_success(status)) {
+		local_irq_restore(flags);
+		hv_status_debug(status, "\n");
+		return hv_result_to_errno(status);
+	}
+	memcpy(property_value, &output->property_value, property_value_sz);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+int
+hv_call_clear_virtual_interrupt(u64 partition_id)
+{
+	int status;
+
+	status = hv_do_fast_hypercall8(HVCALL_CLEAR_VIRTUAL_INTERRUPT,
+				       partition_id);
+
+	return hv_result_to_errno(status);
+}
+
+int
+hv_call_create_port(u64 port_partition_id, union hv_port_id port_id,
+		    u64 connection_partition_id,
+		    struct hv_port_info *port_info,
+		    u8 port_vtl, u8 min_connection_vtl, int node)
+{
+	struct hv_input_create_port *input;
+	unsigned long flags;
+	int ret = 0;
+	int status;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		memset(input, 0, sizeof(*input));
+
+		input->port_partition_id = port_partition_id;
+		input->port_id = port_id;
+		input->connection_partition_id = connection_partition_id;
+		input->port_info = *port_info;
+		input->port_vtl = port_vtl;
+		input->min_connection_vtl = min_connection_vtl;
+		input->proximity_domain_info = hv_numa_node_to_pxm_info(node);
+		status = hv_do_hypercall(HVCALL_CREATE_PORT, input, NULL);
+		local_irq_restore(flags);
+		if (hv_result_success(status))
+			break;
+
+		if (!hv_result_needs_memory(status)) {
+			ret = hv_result_to_errno(status);
+			break;
+		}
+		ret = hv_deposit_memory(port_partition_id, status);
+	} while (!ret);
+
+	return ret;
+}
+
+int
+hv_call_delete_port(u64 port_partition_id, union hv_port_id port_id)
+{
+	union hv_input_delete_port input = { 0 };
+	int status;
+
+	input.port_partition_id = port_partition_id;
+	input.port_id = port_id;
+	status = hv_do_fast_hypercall16(HVCALL_DELETE_PORT,
+					input.as_uint64[0],
+					input.as_uint64[1]);
+
+	return hv_result_to_errno(status);
+}
+
+int
+hv_call_connect_port(u64 port_partition_id, union hv_port_id port_id,
+		     u64 connection_partition_id,
+		     union hv_connection_id connection_id,
+		     struct hv_connection_info *connection_info,
+		     u8 connection_vtl, int node)
+{
+	struct hv_input_connect_port *input;
+	unsigned long flags;
+	int ret = 0, status;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		memset(input, 0, sizeof(*input));
+		input->port_partition_id = port_partition_id;
+		input->port_id = port_id;
+		input->connection_partition_id = connection_partition_id;
+		input->connection_id = connection_id;
+		input->connection_info = *connection_info;
+		input->connection_vtl = connection_vtl;
+		input->proximity_domain_info = hv_numa_node_to_pxm_info(node);
+		status = hv_do_hypercall(HVCALL_CONNECT_PORT, input, NULL);
+
+		local_irq_restore(flags);
+		if (hv_result_success(status))
+			break;
+
+		if (!hv_result_needs_memory(status)) {
+			ret = hv_result_to_errno(status);
+			break;
+		}
+		ret = hv_deposit_memory(connection_partition_id, status);
+	} while (!ret);
+
+	return ret;
+}
+
+int
+hv_call_disconnect_port(u64 connection_partition_id,
+			union hv_connection_id connection_id)
+{
+	union hv_input_disconnect_port input = { 0 };
+	int status;
+
+	input.connection_partition_id = connection_partition_id;
+	input.connection_id = connection_id;
+	input.is_doorbell = 1;
+	status = hv_do_fast_hypercall16(HVCALL_DISCONNECT_PORT,
+					input.as_uint64[0],
+					input.as_uint64[1]);
+
+	return hv_result_to_errno(status);
+}
+
+int
+hv_call_notify_port_ring_empty(u32 sint_index)
+{
+	union hv_input_notify_port_ring_empty input = { 0 };
+	int status;
+
+	input.sint_index = sint_index;
+	status = hv_do_fast_hypercall8(HVCALL_NOTIFY_PORT_RING_EMPTY,
+				       input.as_uint64);
+
+	return hv_result_to_errno(status);
+}
+
+/*
+ * Equivalent of hv_call_map_stats_page() for cases when the caller provides
+ * the map location.
+ *
+ * NOTE: This is a newer hypercall that always supports SELF and PARENT stats
+ * areas, unlike hv_call_map_stats_page().
+ */
+static int hv_call_map_stats_page2(enum hv_stats_object_type type,
+				   const union hv_stats_object_identity *identity,
+				   u64 map_location)
+{
+	unsigned long flags;
+	struct hv_input_map_stats_page2 *input;
+	u64 status;
+	int ret;
+
+	if (!map_location || !mshv_use_overlay_gpfn())
+		return -EINVAL;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		memset(input, 0, sizeof(*input));
+		input->type = type;
+		input->identity = *identity;
+		input->map_location = map_location;
+
+		status = hv_do_hypercall(HVCALL_MAP_STATS_PAGE2, input, NULL);
+
+		local_irq_restore(flags);
+
+		ret = hv_result_to_errno(status);
+
+		if (!ret)
+			break;
+
+		if (!hv_result_needs_memory(status)) {
+			hv_status_debug(status, "\n");
+			break;
+		}
+
+		ret = hv_deposit_memory(hv_current_partition_id, status);
+	} while (!ret);
+
+	return ret;
+}
+
+static int
+hv_stats_get_area_type(enum hv_stats_object_type type,
+		       const union hv_stats_object_identity *identity)
+{
+	switch (type) {
+	case HV_STATS_OBJECT_HYPERVISOR:
+		return identity->hv.stats_area_type;
+	case HV_STATS_OBJECT_LOGICAL_PROCESSOR:
+		return identity->lp.stats_area_type;
+	case HV_STATS_OBJECT_PARTITION:
+		return identity->partition.stats_area_type;
+	case HV_STATS_OBJECT_VP:
+		return identity->vp.stats_area_type;
+	}
+
+	return -EINVAL;
+}
+
+/*
+ * Map a stats page, where the page location is provided by the hypervisor.
+ *
+ * NOTE: The concept of separate SELF and PARENT stats areas does not exist on
+ * older hypervisor versions. All the available stats information can be found
+ * on the SELF page. When attempting to map the PARENT area on a hypervisor
+ * that doesn't support it, return "success" but with a NULL address. The
+ * caller should check for this case and instead fallback to the SELF area
+ * alone.
+ */
+static int
+hv_call_map_stats_page(enum hv_stats_object_type type,
+		       const union hv_stats_object_identity *identity,
+		       struct hv_stats_page **addr)
+{
+	unsigned long flags;
+	struct hv_input_map_stats_page *input;
+	struct hv_output_map_stats_page *output;
+	u64 status, pfn;
+	int ret = 0;
+
+	do {
+		local_irq_save(flags);
+		input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+		output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+		memset(input, 0, sizeof(*input));
+		input->type = type;
+		input->identity = *identity;
+
+		status = hv_do_hypercall(HVCALL_MAP_STATS_PAGE, input, output);
+		pfn = output->map_location;
+
+		local_irq_restore(flags);
+
+		if (!hv_result_needs_memory(status)) {
+			if (hv_result_success(status))
+				break;
+
+			if (hv_stats_get_area_type(type, identity) == HV_STATS_AREA_PARENT &&
+			    hv_result(status) == HV_STATUS_INVALID_PARAMETER) {
+				*addr = NULL;
+				return 0;
+			}
+
+			hv_status_debug(status, "\n");
+			return hv_result_to_errno(status);
+		}
+
+		ret = hv_deposit_memory(hv_current_partition_id, status);
+		if (ret)
+			return ret;
+	} while (!ret);
+
+	*addr = page_address(pfn_to_page(pfn));
+
+	return ret;
+}
+
+int hv_map_stats_page(enum hv_stats_object_type type,
+		      const union hv_stats_object_identity *identity,
+		      struct hv_stats_page **addr)
+{
+	int ret;
+	struct page *allocated_page = NULL;
+
+	if (!addr)
+		return -EINVAL;
+
+	if (mshv_use_overlay_gpfn()) {
+		allocated_page = alloc_page(GFP_KERNEL);
+		if (!allocated_page)
+			return -ENOMEM;
+
+		ret = hv_call_map_stats_page2(type, identity,
+					      page_to_pfn(allocated_page));
+		*addr = page_address(allocated_page);
+	} else {
+		ret = hv_call_map_stats_page(type, identity, addr);
+	}
+
+	if (ret && allocated_page) {
+		__free_page(allocated_page);
+		*addr = NULL;
+	}
+
+	return ret;
+}
+
+static int hv_call_unmap_stats_page(enum hv_stats_object_type type,
+				    const union hv_stats_object_identity *identity)
+{
+	unsigned long flags;
+	struct hv_input_unmap_stats_page *input;
+	u64 status;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	memset(input, 0, sizeof(*input));
+	input->type = type;
+	input->identity = *identity;
+
+	status = hv_do_hypercall(HVCALL_UNMAP_STATS_PAGE, input, NULL);
+	local_irq_restore(flags);
+
+	return hv_result_to_errno(status);
+}
+
+int hv_unmap_stats_page(enum hv_stats_object_type type,
+			struct hv_stats_page *page_addr,
+			const union hv_stats_object_identity *identity)
+{
+	int ret;
+
+	ret = hv_call_unmap_stats_page(type, identity);
+
+	if (mshv_use_overlay_gpfn() && page_addr)
+		__free_page(virt_to_page(page_addr));
+
+	return ret;
+}
+
+int hv_call_modify_spa_host_access(u64 partition_id, struct page **pages,
+				   u64 page_struct_count, u32 host_access,
+				   u32 flags, u8 acquire)
+{
+	struct hv_input_modify_sparse_spa_page_host_access *input_page;
+	u64 status;
+	int done = 0;
+	unsigned long irq_flags, large_shift = 0;
+	u64 page_count = page_struct_count;
+	u16 code = acquire ? HVCALL_ACQUIRE_SPARSE_SPA_PAGE_HOST_ACCESS :
+			     HVCALL_RELEASE_SPARSE_SPA_PAGE_HOST_ACCESS;
+
+	if (page_count == 0)
+		return -EINVAL;
+
+	if (flags & HV_MODIFY_SPA_PAGE_HOST_ACCESS_LARGE_PAGE) {
+		if (!HV_PAGE_COUNT_2M_ALIGNED(page_count))
+			return -EINVAL;
+		large_shift = HV_HYP_LARGE_PAGE_SHIFT - HV_HYP_PAGE_SHIFT;
+		page_count >>= large_shift;
+	}
+
+	while (done < page_count) {
+		ulong i, completed, remain = page_count - done;
+		int rep_count = min(remain,
+				    HV_MODIFY_SPARSE_SPA_PAGE_HOST_ACCESS_MAX_PAGE_COUNT);
+
+		local_irq_save(irq_flags);
+		input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+		memset(input_page, 0, sizeof(*input_page));
+		/* Only set the partition id if you are making the pages
+		 * exclusive
+		 */
+		if (flags & HV_MODIFY_SPA_PAGE_HOST_ACCESS_MAKE_EXCLUSIVE)
+			input_page->partition_id = partition_id;
+		input_page->flags = flags;
+		input_page->host_access = host_access;
+
+		for (i = 0; i < rep_count; i++) {
+			u64 index = (done + i) << large_shift;
+
+			if (index >= page_struct_count)
+				return -EINVAL;
+
+			input_page->spa_page_list[i] =
+						page_to_pfn(pages[index]);
+		}
+
+		status = hv_do_rep_hypercall(code, rep_count, 0, input_page,
+					     NULL);
+		local_irq_restore(irq_flags);
+
+		completed = hv_repcomp(status);
+
+		if (!hv_result_success(status))
+			return hv_result_to_errno(status);
+
+		done += completed;
+	}
+
+	return 0;
+}
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
new file mode 100644
index 000000000..cc2cfce2a
--- /dev/null
+++ b/drivers/hv/mshv_root_main.c
@@ -0,0 +1,2440 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024, Microsoft Corporation.
+ *
+ * The main part of the mshv_root module, providing APIs to create
+ * and manage guest partitions.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/entry-virt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/anon_inodes.h>
+#include <linux/mm.h>
+#include <linux/io.h>
+#include <linux/cpuhotplug.h>
+#include <linux/random.h>
+#include <asm/mshyperv.h>
+#include <linux/hyperv.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/kexec.h>
+#include <linux/page-flags.h>
+#include <linux/crash_dump.h>
+#include <linux/panic_notifier.h>
+#include <linux/vmalloc.h>
+#include <linux/rseq.h>
+
+#include "mshv_eventfd.h"
+#include "mshv.h"
+#include "mshv_root.h"
+
+MODULE_AUTHOR("Microsoft");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Microsoft Hyper-V root partition VMM interface /dev/mshv");
+
+/* HV_THREAD_COUNTER */
+#if defined(CONFIG_X86_64)
+#define HV_VP_COUNTER_ROOT_DISPATCH_THREAD_BLOCKED 202
+#elif defined(CONFIG_ARM64)
+#define HV_VP_COUNTER_ROOT_DISPATCH_THREAD_BLOCKED 95
+#endif
+
+struct mshv_root mshv_root;
+
+enum hv_scheduler_type hv_scheduler_type;
+
+/* Once we implement the fast extended hypercall ABI they can go away. */
+static void * __percpu *root_scheduler_input;
+static void * __percpu *root_scheduler_output;
+
+static long mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
+static int mshv_dev_open(struct inode *inode, struct file *filp);
+static int mshv_dev_release(struct inode *inode, struct file *filp);
+static int mshv_vp_release(struct inode *inode, struct file *filp);
+static long mshv_vp_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
+static int mshv_partition_release(struct inode *inode, struct file *filp);
+static long mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
+static int mshv_vp_mmap(struct file *file, struct vm_area_struct *vma);
+static vm_fault_t mshv_vp_fault(struct vm_fault *vmf);
+static int mshv_init_async_handler(struct mshv_partition *partition);
+static void mshv_async_hvcall_handler(void *data, u64 *status);
+
+static const union hv_input_vtl input_vtl_zero;
+static const union hv_input_vtl input_vtl_normal = {
+	.target_vtl = HV_NORMAL_VTL,
+	.use_target_vtl = 1,
+};
+
+static const struct vm_operations_struct mshv_vp_vm_ops = {
+	.fault = mshv_vp_fault,
+};
+
+static const struct file_operations mshv_vp_fops = {
+	.owner = THIS_MODULE,
+	.release = mshv_vp_release,
+	.unlocked_ioctl = mshv_vp_ioctl,
+	.llseek = noop_llseek,
+	.mmap = mshv_vp_mmap,
+};
+
+static const struct file_operations mshv_partition_fops = {
+	.owner = THIS_MODULE,
+	.release = mshv_partition_release,
+	.unlocked_ioctl = mshv_partition_ioctl,
+	.llseek = noop_llseek,
+};
+
+static const struct file_operations mshv_dev_fops = {
+	.owner = THIS_MODULE,
+	.open = mshv_dev_open,
+	.release = mshv_dev_release,
+	.unlocked_ioctl = mshv_dev_ioctl,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice mshv_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "mshv",
+	.fops = &mshv_dev_fops,
+	.mode = 0600,
+};
+
+/*
+ * Only allow hypercalls that have a u64 partition id as the first member of
+ * the input structure.
+ * These are sorted by value.
+ */
+static u16 mshv_passthru_hvcalls[] = {
+	HVCALL_GET_PARTITION_PROPERTY,
+	HVCALL_GET_PARTITION_PROPERTY_EX,
+	HVCALL_SET_PARTITION_PROPERTY,
+	HVCALL_INSTALL_INTERCEPT,
+	HVCALL_GET_VP_REGISTERS,
+	HVCALL_SET_VP_REGISTERS,
+	HVCALL_TRANSLATE_VIRTUAL_ADDRESS,
+	HVCALL_CLEAR_VIRTUAL_INTERRUPT,
+	HVCALL_REGISTER_INTERCEPT_RESULT,
+	HVCALL_ASSERT_VIRTUAL_INTERRUPT,
+	HVCALL_GET_GPA_PAGES_ACCESS_STATES,
+	HVCALL_SIGNAL_EVENT_DIRECT,
+	HVCALL_POST_MESSAGE_DIRECT,
+	HVCALL_GET_VP_CPUID_VALUES,
+};
+
+/*
+ * Only allow hypercalls that are safe to be called by the VMM with the host
+ * partition as target (i.e. HV_PARTITION_ID_SELF). Carefully audit that a
+ * hypercall cannot be misused by the VMM before adding it to this list.
+ */
+static u16 mshv_self_passthru_hvcalls[] = {
+	HVCALL_GET_PARTITION_PROPERTY,
+	HVCALL_GET_PARTITION_PROPERTY_EX,
+};
+
+static bool mshv_hvcall_is_async(u16 code)
+{
+	switch (code) {
+	case HVCALL_SET_PARTITION_PROPERTY:
+		return true;
+	default:
+		break;
+	}
+	return false;
+}
+
+static bool mshv_passthru_hvcall_allowed(u16 code, u64 pt_id)
+{
+	int i;
+	int n = ARRAY_SIZE(mshv_passthru_hvcalls);
+	u16 *allowed_hvcalls = mshv_passthru_hvcalls;
+
+	if (pt_id == HV_PARTITION_ID_SELF) {
+		n = ARRAY_SIZE(mshv_self_passthru_hvcalls);
+		allowed_hvcalls = mshv_self_passthru_hvcalls;
+	}
+
+	for (i = 0; i < n; ++i)
+		if (allowed_hvcalls[i] == code)
+			return true;
+
+	return false;
+}
+
+static int mshv_ioctl_passthru_hvcall(struct mshv_partition *partition,
+				      bool partition_locked,
+				      void __user *user_args)
+{
+	u64 status;
+	int ret = 0;
+	bool is_async;
+	struct mshv_root_hvcall args;
+	struct page *page;
+	unsigned int pages_order;
+	void *input_pg = NULL;
+	void *output_pg = NULL;
+	u16 reps_completed;
+	u64 pt_id = partition ? partition->pt_id : HV_PARTITION_ID_SELF;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	if (args.status || !args.in_ptr || args.in_sz < sizeof(u64) ||
+	    mshv_field_nonzero(args, rsvd) || args.in_sz > HV_HYP_PAGE_SIZE)
+		return -EINVAL;
+
+	if (args.out_ptr && (!args.out_sz || args.out_sz > HV_HYP_PAGE_SIZE))
+		return -EINVAL;
+
+	if (!mshv_passthru_hvcall_allowed(args.code, pt_id))
+		return -EINVAL;
+
+	is_async = mshv_hvcall_is_async(args.code);
+	if (is_async) {
+		/* async hypercalls can only be called from partition fd */
+		if (!partition || !partition_locked)
+			return -EINVAL;
+		ret = mshv_init_async_handler(partition);
+		if (ret)
+			return ret;
+	}
+
+	pages_order = args.out_ptr ? 1 : 0;
+	page = alloc_pages(GFP_KERNEL, pages_order);
+	if (!page)
+		return -ENOMEM;
+	input_pg = page_address(page);
+
+	if (args.out_ptr)
+		output_pg = (char *)input_pg + PAGE_SIZE;
+	else
+		output_pg = NULL;
+
+	if (copy_from_user(input_pg, (void __user *)args.in_ptr,
+			   args.in_sz)) {
+		ret = -EFAULT;
+		goto free_pages_out;
+	}
+
+	/*
+	 * NOTE: This only works because all the allowed hypercalls' input
+	 * structs begin with a u64 partition_id field.
+	 */
+	*(u64 *)input_pg = pt_id;
+
+	reps_completed = 0;
+	do {
+		if (args.reps) {
+			status = hv_do_rep_hypercall_ex(args.code, args.reps,
+							0, reps_completed,
+							input_pg, output_pg);
+			reps_completed = hv_repcomp(status);
+		} else {
+			status = hv_do_hypercall(args.code, input_pg, output_pg);
+		}
+
+		if (hv_result(status) == HV_STATUS_CALL_PENDING) {
+			if (is_async) {
+				mshv_async_hvcall_handler(partition, &status);
+			} else { /* Paranoia check. This shouldn't happen! */
+				ret = -EBADFD;
+				goto free_pages_out;
+			}
+		}
+
+		if (hv_result_success(status))
+			break;
+
+		if (!hv_result_needs_memory(status))
+			ret = hv_result_to_errno(status);
+		else
+			ret = hv_deposit_memory(pt_id, status);
+	} while (!ret);
+
+	args.status = hv_result(status);
+	args.reps = reps_completed;
+	if (copy_to_user(user_args, &args, sizeof(args)))
+		ret = -EFAULT;
+
+	if (!ret && output_pg &&
+	    copy_to_user((void __user *)args.out_ptr, output_pg, args.out_sz))
+		ret = -EFAULT;
+
+free_pages_out:
+	free_pages((unsigned long)input_pg, pages_order);
+
+	return ret;
+}
+
+static inline bool is_ghcb_mapping_available(void)
+{
+#if IS_ENABLED(CONFIG_X86_64)
+	return ms_hyperv.ext_features & HV_VP_GHCB_ROOT_MAPPING_AVAILABLE;
+#else
+	return 0;
+#endif
+}
+
+static int mshv_get_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+				 struct hv_register_assoc *registers)
+{
+	return hv_call_get_vp_registers(vp_index, partition_id,
+					count, input_vtl_zero, registers);
+}
+
+static int mshv_set_vp_registers(u32 vp_index, u64 partition_id, u16 count,
+				 struct hv_register_assoc *registers)
+{
+	return hv_call_set_vp_registers(vp_index, partition_id,
+					count, input_vtl_zero, registers);
+}
+
+/*
+ * Explicit guest vCPU suspend is asynchronous by nature (as it is requested by
+ * dom0 vCPU for guest vCPU) and thus it can race with "intercept" suspend,
+ * done by the hypervisor.
+ * "Intercept" suspend leads to asynchronous message delivery to dom0 which
+ * should be awaited to keep the VP loop consistent (i.e. no message pending
+ * upon VP resume).
+ * VP intercept suspend can't be done when the VP is explicitly suspended
+ * already, and thus can be only two possible race scenarios:
+ *   1. implicit suspend bit set -> explicit suspend bit set -> message sent
+ *   2. implicit suspend bit set -> message sent -> explicit suspend bit set
+ * Checking for implicit suspend bit set after explicit suspend request has
+ * succeeded in either case allows us to reliably identify, if there is a
+ * message to receive and deliver to VMM.
+ */
+static int
+mshv_suspend_vp(const struct mshv_vp *vp, bool *message_in_flight)
+{
+	struct hv_register_assoc explicit_suspend = {
+		.name = HV_REGISTER_EXPLICIT_SUSPEND
+	};
+	struct hv_register_assoc intercept_suspend = {
+		.name = HV_REGISTER_INTERCEPT_SUSPEND
+	};
+	union hv_explicit_suspend_register *es =
+		&explicit_suspend.value.explicit_suspend;
+	union hv_intercept_suspend_register *is =
+		&intercept_suspend.value.intercept_suspend;
+	int ret;
+
+	es->suspended = 1;
+
+	ret = mshv_set_vp_registers(vp->vp_index, vp->vp_partition->pt_id,
+				    1, &explicit_suspend);
+	if (ret) {
+		vp_err(vp, "Failed to explicitly suspend vCPU\n");
+		return ret;
+	}
+
+	ret = mshv_get_vp_registers(vp->vp_index, vp->vp_partition->pt_id,
+				    1, &intercept_suspend);
+	if (ret) {
+		vp_err(vp, "Failed to get intercept suspend state\n");
+		return ret;
+	}
+
+	*message_in_flight = is->suspended;
+
+	return 0;
+}
+
+/*
+ * This function is used when VPs are scheduled by the hypervisor's
+ * scheduler.
+ *
+ * Caller has to make sure the registers contain cleared
+ * HV_REGISTER_INTERCEPT_SUSPEND and HV_REGISTER_EXPLICIT_SUSPEND registers
+ * exactly in this order (the hypervisor clears them sequentially) to avoid
+ * potential invalid clearing a newly arrived HV_REGISTER_INTERCEPT_SUSPEND
+ * after VP is released from HV_REGISTER_EXPLICIT_SUSPEND in case of the
+ * opposite order.
+ */
+static long mshv_run_vp_with_hyp_scheduler(struct mshv_vp *vp)
+{
+	long ret;
+	struct hv_register_assoc suspend_regs[2] = {
+			{ .name = HV_REGISTER_INTERCEPT_SUSPEND },
+			{ .name = HV_REGISTER_EXPLICIT_SUSPEND }
+	};
+	size_t count = ARRAY_SIZE(suspend_regs);
+
+	/* Resume VP execution */
+	ret = mshv_set_vp_registers(vp->vp_index, vp->vp_partition->pt_id,
+				    count, suspend_regs);
+	if (ret) {
+		vp_err(vp, "Failed to resume vp execution. %lx\n", ret);
+		return ret;
+	}
+
+	ret = wait_event_interruptible(vp->run.vp_suspend_queue,
+				       vp->run.kicked_by_hv == 1);
+	if (ret) {
+		bool message_in_flight;
+
+		/*
+		 * Otherwise the waiting was interrupted by a signal: suspend
+		 * the vCPU explicitly and copy message in flight (if any).
+		 */
+		ret = mshv_suspend_vp(vp, &message_in_flight);
+		if (ret)
+			return ret;
+
+		/* Return if no message in flight */
+		if (!message_in_flight)
+			return -EINTR;
+
+		/* Wait for the message in flight. */
+		wait_event(vp->run.vp_suspend_queue, vp->run.kicked_by_hv == 1);
+	}
+
+	/*
+	 * Reset the flag to make the wait_event call above work
+	 * next time.
+	 */
+	vp->run.kicked_by_hv = 0;
+
+	return 0;
+}
+
+static int
+mshv_vp_dispatch(struct mshv_vp *vp, u32 flags,
+		 struct hv_output_dispatch_vp *res)
+{
+	struct hv_input_dispatch_vp *input;
+	struct hv_output_dispatch_vp *output;
+	u64 status;
+
+	preempt_disable();
+	input = *this_cpu_ptr(root_scheduler_input);
+	output = *this_cpu_ptr(root_scheduler_output);
+
+	memset(input, 0, sizeof(*input));
+	memset(output, 0, sizeof(*output));
+
+	input->partition_id = vp->vp_partition->pt_id;
+	input->vp_index = vp->vp_index;
+	input->time_slice = 0; /* Run forever until something happens */
+	input->spec_ctrl = 0; /* TODO: set sensible flags */
+	input->flags = flags;
+
+	vp->run.flags.root_sched_dispatched = 1;
+	status = hv_do_hypercall(HVCALL_DISPATCH_VP, input, output);
+	vp->run.flags.root_sched_dispatched = 0;
+
+	trace_mshv_hvcall_dispatch_vp(vp->vp_partition->pt_id,
+				      vp->vp_index, flags,
+				      output->dispatch_state,
+				      output->dispatch_event,
+#if defined(CONFIG_X86_64)
+				      vp->vp_register_page->interrupt_vectors.as_uint64,
+#else
+				      0,
+#endif
+				      status);
+
+	*res = *output;
+	preempt_enable();
+
+	if (!hv_result_success(status))
+		vp_err(vp, "%s: status %s\n", __func__,
+		       hv_result_to_string(status));
+
+	return hv_result_to_errno(status);
+}
+
+static int
+mshv_vp_clear_explicit_suspend(struct mshv_vp *vp)
+{
+	struct hv_register_assoc explicit_suspend = {
+		.name = HV_REGISTER_EXPLICIT_SUSPEND,
+		.value.explicit_suspend.suspended = 0,
+	};
+	int ret;
+
+	ret = mshv_set_vp_registers(vp->vp_index, vp->vp_partition->pt_id,
+				    1, &explicit_suspend);
+
+	trace_mshv_vp_clear_explicit_suspend(vp->vp_partition->pt_id,
+					     vp->vp_index, ret);
+
+	if (ret)
+		vp_err(vp, "Failed to unsuspend\n");
+
+	return ret;
+}
+
+#if IS_ENABLED(CONFIG_X86_64)
+static u64 mshv_vp_interrupt_pending(struct mshv_vp *vp)
+{
+	if (!vp->vp_register_page)
+		return 0;
+	return vp->vp_register_page->interrupt_vectors.as_uint64;
+}
+#else
+static u64 mshv_vp_interrupt_pending(struct mshv_vp *vp)
+{
+	return 0;
+}
+#endif
+
+static bool mshv_vp_dispatch_thread_blocked(struct mshv_vp *vp)
+{
+	struct hv_stats_page **stats = vp->vp_stats_pages;
+	u64 *self_vp_cntrs = stats[HV_STATS_AREA_SELF]->data;
+	u64 *parent_vp_cntrs = stats[HV_STATS_AREA_PARENT]->data;
+
+	return parent_vp_cntrs[HV_VP_COUNTER_ROOT_DISPATCH_THREAD_BLOCKED] ||
+	       self_vp_cntrs[HV_VP_COUNTER_ROOT_DISPATCH_THREAD_BLOCKED];
+}
+
+static int
+mshv_vp_wait_for_hv_kick(struct mshv_vp *vp)
+{
+	int ret;
+
+	ret = wait_event_interruptible(vp->run.vp_suspend_queue,
+				       (vp->run.kicked_by_hv == 1 &&
+					!mshv_vp_dispatch_thread_blocked(vp)) ||
+				       mshv_vp_interrupt_pending(vp));
+	if (ret)
+		return -EINTR;
+
+	trace_mshv_vp_wait_for_hv_kick(vp->vp_partition->pt_id,
+				       vp->vp_index,
+				       vp->run.kicked_by_hv,
+				       mshv_vp_dispatch_thread_blocked(vp),
+				       mshv_vp_interrupt_pending(vp));
+
+	vp->run.flags.root_sched_blocked = 0;
+	vp->run.kicked_by_hv = 0;
+
+	return 0;
+}
+
+/* Must be called with interrupts enabled */
+static long mshv_run_vp_with_root_scheduler(struct mshv_vp *vp)
+{
+	long ret;
+
+	if (vp->run.flags.root_sched_blocked) {
+		/*
+		 * Dispatch state of this VP is blocked. Need to wait
+		 * for the hypervisor to clear the blocked state before
+		 * dispatching it.
+		 */
+		ret = mshv_vp_wait_for_hv_kick(vp);
+		if (ret)
+			return ret;
+	}
+
+	do {
+		u32 flags = 0;
+		struct hv_output_dispatch_vp output;
+
+		if (__xfer_to_guest_mode_work_pending()) {
+			ret = xfer_to_guest_mode_handle_work();
+
+			trace_mshv_xfer_to_guest_mode_work(vp->vp_partition->pt_id,
+							   vp->vp_index,
+							   read_thread_flags(),
+							   ret);
+
+			if (ret)
+				break;
+		}
+
+		if (vp->run.flags.intercept_suspend)
+			flags |= HV_DISPATCH_VP_FLAG_CLEAR_INTERCEPT_SUSPEND;
+
+		if (mshv_vp_interrupt_pending(vp))
+			flags |= HV_DISPATCH_VP_FLAG_SCAN_INTERRUPT_INJECTION;
+
+		ret = mshv_vp_dispatch(vp, flags, &output);
+		if (ret)
+			break;
+
+		vp->run.flags.intercept_suspend = 0;
+
+		if (output.dispatch_state == HV_VP_DISPATCH_STATE_BLOCKED) {
+			if (output.dispatch_event ==
+						HV_VP_DISPATCH_EVENT_SUSPEND) {
+				/*
+				 * TODO: remove the warning once VP canceling
+				 *	 is supported
+				 */
+				WARN_ONCE(atomic64_read(&vp->run.vp_signaled_count),
+					  "%s: vp#%d: unexpected explicit suspend\n",
+					  __func__, vp->vp_index);
+				/*
+				 * Need to clear explicit suspend before
+				 * dispatching.
+				 * Explicit suspend is either:
+				 * - set right after the first VP dispatch or
+				 * - set explicitly via hypercall
+				 * Since the latter case is not yet supported,
+				 * simply clear it here.
+				 */
+				ret = mshv_vp_clear_explicit_suspend(vp);
+				if (ret)
+					break;
+
+				ret = mshv_vp_wait_for_hv_kick(vp);
+				if (ret)
+					break;
+			} else {
+				vp->run.flags.root_sched_blocked = 1;
+				ret = mshv_vp_wait_for_hv_kick(vp);
+				if (ret)
+					break;
+			}
+		} else {
+			/* HV_VP_DISPATCH_STATE_READY */
+			if (output.dispatch_event ==
+						HV_VP_DISPATCH_EVENT_INTERCEPT)
+				vp->run.flags.intercept_suspend = 1;
+		}
+	} while (!vp->run.flags.intercept_suspend);
+
+	rseq_virt_userspace_exit();
+
+	return ret;
+}
+
+static_assert(sizeof(struct hv_message) <= MSHV_RUN_VP_BUF_SZ,
+	      "sizeof(struct hv_message) must not exceed MSHV_RUN_VP_BUF_SZ");
+
+static struct mshv_mem_region *
+mshv_partition_region_by_gfn(struct mshv_partition *partition, u64 gfn)
+{
+	struct mshv_mem_region *region;
+
+	hlist_for_each_entry(region, &partition->pt_mem_regions, hnode) {
+		if (gfn >= region->start_gfn &&
+		    gfn < region->start_gfn + region->nr_pages)
+			return region;
+	}
+
+	return NULL;
+}
+
+static struct mshv_mem_region *
+mshv_partition_region_by_gfn_get(struct mshv_partition *p, u64 gfn)
+{
+	struct mshv_mem_region *region;
+
+	spin_lock(&p->pt_mem_regions_lock);
+	region = mshv_partition_region_by_gfn(p, gfn);
+	if (!region || !mshv_region_get(region)) {
+		spin_unlock(&p->pt_mem_regions_lock);
+		return NULL;
+	}
+	spin_unlock(&p->pt_mem_regions_lock);
+
+	return region;
+}
+
+/**
+ * mshv_handle_gpa_intercept - Handle GPA (Guest Physical Address) intercepts.
+ * @vp: Pointer to the virtual processor structure.
+ *
+ * This function processes GPA intercepts by identifying the memory region
+ * corresponding to the intercepted GPA, aligning the page offset, and
+ * mapping the required pages. It ensures that the region is valid and
+ * handles faults efficiently by mapping multiple pages at once.
+ *
+ * Return: true if the intercept was handled successfully, false otherwise.
+ */
+static bool mshv_handle_gpa_intercept(struct mshv_vp *vp)
+{
+	struct mshv_partition *p = vp->vp_partition;
+	struct mshv_mem_region *region;
+	bool ret = false;
+	u64 gfn;
+#if defined(CONFIG_X86_64)
+	struct hv_x64_memory_intercept_message *msg =
+		(struct hv_x64_memory_intercept_message *)
+		vp->vp_intercept_msg_page->u.payload;
+#elif defined(CONFIG_ARM64)
+	struct hv_arm64_memory_intercept_message *msg =
+		(struct hv_arm64_memory_intercept_message *)
+		vp->vp_intercept_msg_page->u.payload;
+#endif
+	enum hv_intercept_access_type access_type =
+		msg->header.intercept_access_type;
+
+	gfn = HVPFN_DOWN(msg->guest_physical_address);
+
+	region = mshv_partition_region_by_gfn_get(p, gfn);
+	if (!region)
+		goto out;
+
+	if (access_type == HV_INTERCEPT_ACCESS_WRITE &&
+	    !(region->hv_map_flags & HV_MAP_GPA_WRITABLE))
+		goto put_region;
+
+	if (access_type == HV_INTERCEPT_ACCESS_EXECUTE &&
+	    !(region->hv_map_flags & HV_MAP_GPA_EXECUTABLE))
+		goto put_region;
+
+	/* Only movable memory ranges are supported for GPA intercepts */
+	if (region->mreg_type == MSHV_REGION_TYPE_MEM_MOVABLE)
+		ret = mshv_region_handle_gfn_fault(region, gfn);
+
+put_region:
+	mshv_region_put(region);
+out:
+	trace_mshv_handle_gpa_intercept(p->pt_id, vp->vp_index, gfn,
+					access_type, ret);
+	return ret;
+}
+
+static bool mshv_vp_handle_intercept(struct mshv_vp *vp)
+{
+	switch (vp->vp_intercept_msg_page->header.message_type) {
+	case HVMSG_GPA_INTERCEPT:
+		return mshv_handle_gpa_intercept(vp);
+	}
+	return false;
+}
+
+static long mshv_vp_ioctl_run_vp(struct mshv_vp *vp, void __user *ret_msg)
+{
+	long rc;
+
+	trace_mshv_run_vp_entry(vp->vp_partition->pt_id, vp->vp_index);
+
+	do {
+		if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
+			rc = mshv_run_vp_with_root_scheduler(vp);
+		else
+			rc = mshv_run_vp_with_hyp_scheduler(vp);
+	} while (rc == 0 && mshv_vp_handle_intercept(vp));
+
+	trace_mshv_run_vp_exit(vp->vp_partition->pt_id, vp->vp_index,
+			       vp->vp_intercept_msg_page->header.message_type,
+			       rc);
+
+	if (rc)
+		return rc;
+
+	if (copy_to_user(ret_msg, vp->vp_intercept_msg_page,
+			 sizeof(struct hv_message)))
+		rc = -EFAULT;
+
+	return rc;
+}
+
+static int
+mshv_vp_ioctl_get_set_state_pfn(struct mshv_vp *vp,
+				struct hv_vp_state_data state_data,
+				unsigned long user_pfn, size_t page_count,
+				bool is_set)
+{
+	int completed, ret = 0;
+	unsigned long check;
+	struct page **pages;
+
+	if (page_count > INT_MAX)
+		return -EINVAL;
+	/*
+	 * Check the arithmetic for wraparound/overflow.
+	 * The last page address in the buffer is:
+	 * (user_pfn + (page_count - 1)) * PAGE_SIZE
+	 */
+	if (check_add_overflow(user_pfn, (page_count - 1), &check))
+		return -EOVERFLOW;
+	if (check_mul_overflow(check, PAGE_SIZE, &check))
+		return -EOVERFLOW;
+
+	/* Pin user pages so hypervisor can copy directly to them */
+	pages = kzalloc_objs(struct page *, page_count);
+	if (!pages)
+		return -ENOMEM;
+
+	for (completed = 0; completed < page_count; completed += ret) {
+		unsigned long user_addr = (user_pfn + completed) * PAGE_SIZE;
+		int remaining = page_count - completed;
+
+		ret = pin_user_pages_fast(user_addr, remaining, FOLL_WRITE,
+					  &pages[completed]);
+		if (ret < 0) {
+			vp_err(vp, "%s: Failed to pin user pages error %i\n",
+			       __func__, ret);
+			goto unpin_pages;
+		}
+	}
+
+	if (is_set)
+		ret = hv_call_set_vp_state(vp->vp_index,
+					   vp->vp_partition->pt_id,
+					   state_data, page_count, pages,
+					   0, NULL);
+	else
+		ret = hv_call_get_vp_state(vp->vp_index,
+					   vp->vp_partition->pt_id,
+					   state_data, page_count, pages,
+					   NULL);
+
+unpin_pages:
+	unpin_user_pages(pages, completed);
+	kfree(pages);
+	return ret;
+}
+
+static long
+mshv_vp_ioctl_get_set_state(struct mshv_vp *vp,
+			    struct mshv_get_set_vp_state __user *user_args,
+			    bool is_set)
+{
+	struct mshv_get_set_vp_state args;
+	long ret = 0;
+	union hv_output_get_vp_state vp_state;
+	u32 data_sz;
+	struct hv_vp_state_data state_data = {};
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	if (args.type >= MSHV_VP_STATE_COUNT || mshv_field_nonzero(args, rsvd) ||
+	    !args.buf_sz || !PAGE_ALIGNED(args.buf_sz) ||
+	    !PAGE_ALIGNED(args.buf_ptr))
+		return -EINVAL;
+
+	if (!access_ok((void __user *)args.buf_ptr, args.buf_sz))
+		return -EFAULT;
+
+	switch (args.type) {
+	case MSHV_VP_STATE_LAPIC:
+		state_data.type = HV_GET_SET_VP_STATE_LAPIC_STATE;
+		data_sz = HV_HYP_PAGE_SIZE;
+		break;
+	case MSHV_VP_STATE_XSAVE:
+	{
+		u64 data_sz_64;
+
+		ret = hv_call_get_partition_property(vp->vp_partition->pt_id,
+						     HV_PARTITION_PROPERTY_XSAVE_STATES,
+						     &state_data.xsave.states.as_uint64);
+		if (ret)
+			return ret;
+
+		ret = hv_call_get_partition_property(vp->vp_partition->pt_id,
+						     HV_PARTITION_PROPERTY_MAX_XSAVE_DATA_SIZE,
+						     &data_sz_64);
+		if (ret)
+			return ret;
+
+		data_sz = (u32)data_sz_64;
+		state_data.xsave.flags = 0;
+		/* Always request legacy states */
+		state_data.xsave.states.legacy_x87 = 1;
+		state_data.xsave.states.legacy_sse = 1;
+		state_data.type = HV_GET_SET_VP_STATE_XSAVE;
+		break;
+	}
+	case MSHV_VP_STATE_SIMP:
+		state_data.type = HV_GET_SET_VP_STATE_SIM_PAGE;
+		data_sz = HV_HYP_PAGE_SIZE;
+		break;
+	case MSHV_VP_STATE_SIEFP:
+		state_data.type = HV_GET_SET_VP_STATE_SIEF_PAGE;
+		data_sz = HV_HYP_PAGE_SIZE;
+		break;
+	case MSHV_VP_STATE_SYNTHETIC_TIMERS:
+		state_data.type = HV_GET_SET_VP_STATE_SYNTHETIC_TIMERS;
+		data_sz = sizeof(vp_state.synthetic_timers_state);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (copy_to_user(&user_args->buf_sz, &data_sz, sizeof(user_args->buf_sz)))
+		return -EFAULT;
+
+	if (data_sz > args.buf_sz)
+		return -EINVAL;
+
+	/* If the data is transmitted via pfns, delegate to helper */
+	if (state_data.type & HV_GET_SET_VP_STATE_TYPE_PFN) {
+		unsigned long user_pfn = PFN_DOWN(args.buf_ptr);
+		size_t page_count = PFN_DOWN(args.buf_sz);
+
+		return mshv_vp_ioctl_get_set_state_pfn(vp, state_data, user_pfn,
+						       page_count, is_set);
+	}
+
+	/* Paranoia check - this shouldn't happen! */
+	if (data_sz > sizeof(vp_state)) {
+		vp_err(vp, "Invalid vp state data size!\n");
+		return -EINVAL;
+	}
+
+	if (is_set) {
+		if (copy_from_user(&vp_state, (__user void *)args.buf_ptr, data_sz))
+			return -EFAULT;
+
+		return hv_call_set_vp_state(vp->vp_index,
+					    vp->vp_partition->pt_id,
+					    state_data, 0, NULL,
+					    sizeof(vp_state), (u8 *)&vp_state);
+	}
+
+	ret = hv_call_get_vp_state(vp->vp_index, vp->vp_partition->pt_id,
+				   state_data, 0, NULL, &vp_state);
+	if (ret)
+		return ret;
+
+	if (copy_to_user((void __user *)args.buf_ptr, &vp_state, data_sz))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long
+mshv_vp_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	struct mshv_vp *vp = filp->private_data;
+	long r = -ENOTTY;
+
+	if (mutex_lock_killable(&vp->vp_mutex))
+		return -EINTR;
+
+	switch (ioctl) {
+	case MSHV_RUN_VP:
+		r = mshv_vp_ioctl_run_vp(vp, (void __user *)arg);
+		break;
+	case MSHV_GET_VP_STATE:
+		r = mshv_vp_ioctl_get_set_state(vp, (void __user *)arg, false);
+		break;
+	case MSHV_SET_VP_STATE:
+		r = mshv_vp_ioctl_get_set_state(vp, (void __user *)arg, true);
+		break;
+	case MSHV_ROOT_HVCALL:
+		r = mshv_ioctl_passthru_hvcall(vp->vp_partition, false,
+					       (void __user *)arg);
+		break;
+	default:
+		vp_warn(vp, "Invalid ioctl: %#x\n", ioctl);
+		break;
+	}
+	mutex_unlock(&vp->vp_mutex);
+
+	return r;
+}
+
+static vm_fault_t mshv_vp_fault(struct vm_fault *vmf)
+{
+	struct mshv_vp *vp = vmf->vma->vm_file->private_data;
+
+	switch (vmf->vma->vm_pgoff) {
+	case MSHV_VP_MMAP_OFFSET_REGISTERS:
+		vmf->page = virt_to_page(vp->vp_register_page);
+		break;
+	case MSHV_VP_MMAP_OFFSET_INTERCEPT_MESSAGE:
+		vmf->page = virt_to_page(vp->vp_intercept_msg_page);
+		break;
+	case MSHV_VP_MMAP_OFFSET_GHCB:
+		vmf->page = virt_to_page(vp->vp_ghcb_page);
+		break;
+	default:
+		return VM_FAULT_SIGBUS;
+	}
+
+	get_page(vmf->page);
+
+	return 0;
+}
+
+static int mshv_vp_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct mshv_vp *vp = file->private_data;
+
+	switch (vma->vm_pgoff) {
+	case MSHV_VP_MMAP_OFFSET_REGISTERS:
+		if (!vp->vp_register_page)
+			return -ENODEV;
+		break;
+	case MSHV_VP_MMAP_OFFSET_INTERCEPT_MESSAGE:
+		if (!vp->vp_intercept_msg_page)
+			return -ENODEV;
+		break;
+	case MSHV_VP_MMAP_OFFSET_GHCB:
+		if (!vp->vp_ghcb_page)
+			return -ENODEV;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	vma->vm_ops = &mshv_vp_vm_ops;
+	return 0;
+}
+
+static int
+mshv_vp_release(struct inode *inode, struct file *filp)
+{
+	struct mshv_vp *vp = filp->private_data;
+
+	trace_mshv_vp_release(vp->vp_partition->pt_id, vp->vp_index);
+
+	/* Rest of VP cleanup happens in destroy_partition() */
+	mshv_partition_put(vp->vp_partition);
+	return 0;
+}
+
+void mshv_vp_stats_unmap(u64 partition_id, u32 vp_index,
+			 struct hv_stats_page *stats_pages[])
+{
+	union hv_stats_object_identity identity = {
+		.vp.partition_id = partition_id,
+		.vp.vp_index = vp_index,
+	};
+	int err;
+
+	identity.vp.stats_area_type = HV_STATS_AREA_SELF;
+	err = hv_unmap_stats_page(HV_STATS_OBJECT_VP,
+				  stats_pages[HV_STATS_AREA_SELF],
+				  &identity);
+	if (err)
+		pr_err("%s: failed to unmap partition %llu vp %u self stats, err: %d\n",
+		       __func__, partition_id, vp_index, err);
+
+	if (stats_pages[HV_STATS_AREA_PARENT] != stats_pages[HV_STATS_AREA_SELF]) {
+		identity.vp.stats_area_type = HV_STATS_AREA_PARENT;
+		err = hv_unmap_stats_page(HV_STATS_OBJECT_VP,
+					  stats_pages[HV_STATS_AREA_PARENT],
+					  &identity);
+		if (err)
+			pr_err("%s: failed to unmap partition %llu vp %u parent stats, err: %d\n",
+			       __func__, partition_id, vp_index, err);
+	}
+}
+
+int mshv_vp_stats_map(u64 partition_id, u32 vp_index,
+		      struct hv_stats_page *stats_pages[])
+{
+	union hv_stats_object_identity identity = {
+		.vp.partition_id = partition_id,
+		.vp.vp_index = vp_index,
+	};
+	int err;
+
+	identity.vp.stats_area_type = HV_STATS_AREA_SELF;
+	err = hv_map_stats_page(HV_STATS_OBJECT_VP, &identity,
+				&stats_pages[HV_STATS_AREA_SELF]);
+	if (err) {
+		pr_err("%s: failed to map partition %llu vp %u self stats, err: %d\n",
+		       __func__, partition_id, vp_index, err);
+		return err;
+	}
+
+	/*
+	 * L1VH partition cannot access its vp stats in parent area.
+	 */
+	if (is_l1vh_parent(partition_id)) {
+		stats_pages[HV_STATS_AREA_PARENT] = stats_pages[HV_STATS_AREA_SELF];
+	} else {
+		identity.vp.stats_area_type = HV_STATS_AREA_PARENT;
+		err = hv_map_stats_page(HV_STATS_OBJECT_VP, &identity,
+					&stats_pages[HV_STATS_AREA_PARENT]);
+		if (err) {
+			pr_err("%s: failed to map partition %llu vp %u parent stats, err: %d\n",
+			       __func__, partition_id, vp_index, err);
+			goto unmap_self;
+		}
+		if (!stats_pages[HV_STATS_AREA_PARENT])
+			stats_pages[HV_STATS_AREA_PARENT] = stats_pages[HV_STATS_AREA_SELF];
+	}
+
+	return 0;
+
+unmap_self:
+	identity.vp.stats_area_type = HV_STATS_AREA_SELF;
+	hv_unmap_stats_page(HV_STATS_OBJECT_VP,
+			    stats_pages[HV_STATS_AREA_SELF],
+			    &identity);
+	return err;
+}
+
+static long
+mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
+			       void __user *arg)
+{
+	struct mshv_create_vp args;
+	struct mshv_vp *vp;
+	struct page *intercept_msg_page, *register_page, *ghcb_page;
+	struct hv_stats_page *stats_pages[2];
+	struct file *file;
+	int fd;
+	long ret;
+
+	if (copy_from_user(&args, arg, sizeof(args)))
+		return -EFAULT;
+
+	if (args.vp_index >= MSHV_MAX_VPS)
+		return -EINVAL;
+
+	if (partition->pt_vp_array[args.vp_index])
+		return -EEXIST;
+
+	ret = hv_call_create_vp(NUMA_NO_NODE, partition->pt_id, args.vp_index,
+				0 /* Only valid for root partition VPs */);
+	if (ret)
+		return ret;
+
+	ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
+				   HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
+				   input_vtl_zero, &intercept_msg_page);
+	if (ret)
+		goto destroy_vp;
+
+	if (!mshv_partition_encrypted(partition)) {
+		ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
+					   HV_VP_STATE_PAGE_REGISTERS,
+					   input_vtl_zero, &register_page);
+		if (ret)
+			goto unmap_intercept_message_page;
+	}
+
+	if (mshv_partition_encrypted(partition) &&
+	    is_ghcb_mapping_available()) {
+		ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
+					   HV_VP_STATE_PAGE_GHCB,
+					   input_vtl_normal, &ghcb_page);
+		if (ret)
+			goto unmap_register_page;
+	}
+
+	ret = mshv_vp_stats_map(partition->pt_id, args.vp_index,
+				stats_pages);
+	if (ret)
+		goto unmap_ghcb_page;
+
+	vp = kzalloc_obj(*vp);
+	if (!vp) {
+		ret = -ENOMEM;
+		goto unmap_stats_pages;
+	}
+
+	vp->vp_partition = mshv_partition_get(partition);
+	if (!vp->vp_partition) {
+		ret = -EBADF;
+		goto free_vp;
+	}
+
+	mutex_init(&vp->vp_mutex);
+	init_waitqueue_head(&vp->run.vp_suspend_queue);
+	atomic64_set(&vp->run.vp_signaled_count, 0);
+
+	vp->vp_index = args.vp_index;
+	vp->vp_intercept_msg_page = page_to_virt(intercept_msg_page);
+	if (!mshv_partition_encrypted(partition))
+		vp->vp_register_page = page_to_virt(register_page);
+
+	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
+		vp->vp_ghcb_page = page_to_virt(ghcb_page);
+
+	memcpy(vp->vp_stats_pages, stats_pages, sizeof(stats_pages));
+
+	ret = mshv_debugfs_vp_create(vp);
+	if (ret)
+		goto put_partition;
+
+	fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+	if (fd < 0) {
+		ret = fd;
+		goto remove_debugfs_vp;
+	}
+
+	file = anon_inode_getfile("mshv_vp", &mshv_vp_fops, vp,
+				  O_RDWR | O_CLOEXEC);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto put_unused_vp_fd;
+	}
+
+	/* already exclusive with the partition mutex for all ioctls */
+	partition->pt_vp_count++;
+	/*
+	 * Pairs with smp_load_acquire() in mshv_try_assert_irq_fast(), which
+	 * can run concurrently from an irqfd waker without holding pt_mutex.
+	 * The release ensures the VP's initialising stores are visible to any
+	 * reader that observes a non-NULL pointer in pt_vp_array.
+	 */
+	smp_store_release(&partition->pt_vp_array[args.vp_index], vp);
+
+	/*
+	 * fd_install() is the userspace-visibility commit point.  Must be the
+	 * last operation that can fail or be observed.
+	 */
+	fd_install(fd, file);
+	ret = fd;
+
+	goto out;
+
+put_unused_vp_fd:
+	put_unused_fd(fd);
+remove_debugfs_vp:
+	mshv_debugfs_vp_remove(vp);
+put_partition:
+	mshv_partition_put(partition);
+free_vp:
+	kfree(vp);
+unmap_stats_pages:
+	mshv_vp_stats_unmap(partition->pt_id, args.vp_index, stats_pages);
+unmap_ghcb_page:
+	if (mshv_partition_encrypted(partition) && is_ghcb_mapping_available())
+		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
+				       HV_VP_STATE_PAGE_GHCB, ghcb_page,
+				       input_vtl_normal);
+unmap_register_page:
+	if (!mshv_partition_encrypted(partition))
+		hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
+				       HV_VP_STATE_PAGE_REGISTERS,
+				       register_page, input_vtl_zero);
+unmap_intercept_message_page:
+	hv_unmap_vp_state_page(partition->pt_id, args.vp_index,
+			       HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
+			       intercept_msg_page, input_vtl_zero);
+destroy_vp:
+	hv_call_delete_vp(partition->pt_id, args.vp_index);
+out:
+	trace_mshv_create_vp(partition->pt_id, args.vp_index, ret);
+	return ret;
+}
+
+static int mshv_init_async_handler(struct mshv_partition *partition)
+{
+	if (completion_done(&partition->async_hypercall)) {
+		pt_err(partition,
+		       "Cannot issue async hypercall while another one in progress!\n");
+		return -EPERM;
+	}
+
+	reinit_completion(&partition->async_hypercall);
+	return 0;
+}
+
+static void mshv_async_hvcall_handler(void *data, u64 *status)
+{
+	struct mshv_partition *partition = data;
+
+	wait_for_completion(&partition->async_hypercall);
+	pt_dbg(partition, "Async hypercall completed!\n");
+
+	*status = partition->async_hypercall_status;
+}
+
+/*
+ * NB: caller checks and makes sure mem->size is page aligned
+ * Returns: 0 with regionpp updated on success, or -errno
+ */
+static int mshv_partition_create_region(struct mshv_partition *partition,
+					struct mshv_user_mem_region *mem,
+					struct mshv_mem_region **regionpp,
+					bool is_mmio)
+{
+	struct mshv_mem_region *rg;
+	u64 nr_pages = HVPFN_DOWN(mem->size);
+
+	/* Reject overlapping regions */
+	spin_lock(&partition->pt_mem_regions_lock);
+	hlist_for_each_entry(rg, &partition->pt_mem_regions, hnode) {
+		if (mem->guest_pfn + nr_pages <= rg->start_gfn ||
+		    rg->start_gfn + rg->nr_pages <= mem->guest_pfn)
+			continue;
+		spin_unlock(&partition->pt_mem_regions_lock);
+		return -EEXIST;
+	}
+	spin_unlock(&partition->pt_mem_regions_lock);
+
+	rg = mshv_region_create(mem->guest_pfn, nr_pages,
+				mem->userspace_addr, mem->flags);
+	if (IS_ERR(rg))
+		return PTR_ERR(rg);
+
+	if (is_mmio)
+		rg->mreg_type = MSHV_REGION_TYPE_MMIO;
+	else if (mshv_partition_encrypted(partition) ||
+		 !mshv_region_movable_init(rg))
+		rg->mreg_type = MSHV_REGION_TYPE_MEM_PINNED;
+	else
+		rg->mreg_type = MSHV_REGION_TYPE_MEM_MOVABLE;
+
+	rg->partition = partition;
+
+	*regionpp = rg;
+
+	return 0;
+}
+
+/**
+ * mshv_prepare_pinned_region - Pin and map memory regions
+ * @region: Pointer to the memory region structure
+ *
+ * This function processes memory regions that are explicitly marked as pinned.
+ * Pinned regions are preallocated, mapped upfront, and do not rely on fault-based
+ * population. The function ensures the region is properly populated, handles
+ * encryption requirements for SNP partitions if applicable, maps the region,
+ * and performs necessary sharing or eviction operations based on the mapping
+ * result.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static int mshv_prepare_pinned_region(struct mshv_mem_region *region)
+{
+	struct mshv_partition *partition = region->partition;
+	int ret;
+
+	ret = mshv_region_pin(region);
+	if (ret) {
+		pt_err(partition, "Failed to pin memory region: %d\n",
+		       ret);
+		goto err_out;
+	}
+
+	/*
+	 * For an SNP partition it is a requirement that for every memory region
+	 * that we are going to map for this partition we should make sure that
+	 * host access to that region is released. This is ensured by doing an
+	 * additional hypercall which will update the SLAT to release host
+	 * access to guest memory regions.
+	 */
+	if (mshv_partition_encrypted(partition)) {
+		ret = mshv_region_unshare(region);
+		if (ret) {
+			pt_err(partition,
+			       "Failed to unshare memory region (guest_pfn: %llu): %d\n",
+			       region->start_gfn, ret);
+			goto invalidate_region;
+		}
+	}
+
+	ret = mshv_region_map(region);
+	if (ret && mshv_partition_encrypted(partition)) {
+		int shrc;
+
+		shrc = mshv_region_share(region);
+		if (!shrc)
+			goto invalidate_region;
+
+		pt_err(partition,
+		       "Failed to share memory region (guest_pfn: %llu): %d\n",
+		       region->start_gfn, shrc);
+		/*
+		 * Don't unpin if marking shared failed because pages are no
+		 * longer mapped in the host, ie root, anymore.
+		 */
+		goto err_out;
+	}
+
+	return 0;
+
+invalidate_region:
+	mshv_region_invalidate(region);
+err_out:
+	return ret;
+}
+
+/*
+ * This maps two things: guest RAM and for pci passthru mmio space.
+ *
+ * mmio:
+ *  - vfio overloads vm_pgoff to store the mmio start pfn/spa.
+ *  - Two things need to happen for mapping mmio range:
+ *	1. mapped in the uaddr so VMM can access it.
+ *	2. mapped in the hwpt (gfn <-> mmio phys addr) so guest can access it.
+ *
+ *   This function takes care of the second. The first one is managed by vfio,
+ *   and hence is taken care of via vfio_pci_mmap_fault().
+ */
+static long
+mshv_map_user_memory(struct mshv_partition *partition,
+		     struct mshv_user_mem_region *mem)
+{
+	struct mshv_mem_region *region;
+	struct vm_area_struct *vma;
+	bool is_mmio;
+	ulong mmio_pfn;
+	long ret;
+
+	if (mem->flags & BIT(MSHV_SET_MEM_BIT_UNMAP) ||
+	    !access_ok((const void __user *)mem->userspace_addr, mem->size))
+		return -EINVAL;
+
+	mmap_read_lock(current->mm);
+	vma = vma_lookup(current->mm, mem->userspace_addr);
+	is_mmio = vma ? !!(vma->vm_flags & (VM_IO | VM_PFNMAP)) : 0;
+	mmio_pfn = is_mmio ? vma->vm_pgoff : 0;
+	mmap_read_unlock(current->mm);
+
+	if (!vma)
+		return -EINVAL;
+
+	ret = mshv_partition_create_region(partition, mem, &region,
+					   is_mmio);
+	if (ret)
+		return ret;
+
+	switch (region->mreg_type) {
+	case MSHV_REGION_TYPE_MEM_PINNED:
+		ret = mshv_prepare_pinned_region(region);
+		break;
+	case MSHV_REGION_TYPE_MEM_MOVABLE:
+		/*
+		 * For movable memory regions, remap with no access to let
+		 * the hypervisor track dirty pages, enabling pre-copy live
+		 * migration.
+		 */
+		ret = hv_call_map_gpa_pages(partition->pt_id,
+					    region->start_gfn,
+					    region->nr_pages,
+					    HV_MAP_GPA_NO_ACCESS, NULL);
+		break;
+	case MSHV_REGION_TYPE_MMIO:
+		ret = hv_call_map_mmio_pages(partition->pt_id,
+					     region->start_gfn,
+					     mmio_pfn,
+					     region->nr_pages);
+		break;
+	}
+
+	trace_mshv_map_user_memory(partition->pt_id, region->start_uaddr,
+				   region->start_gfn, region->nr_pages,
+				   region->hv_map_flags, ret);
+
+	if (ret)
+		goto errout;
+
+	spin_lock(&partition->pt_mem_regions_lock);
+	hlist_add_head(&region->hnode, &partition->pt_mem_regions);
+	spin_unlock(&partition->pt_mem_regions_lock);
+
+	return 0;
+
+errout:
+	mshv_region_put(region);
+	return ret;
+}
+
+/* Called for unmapping both the guest ram and the mmio space */
+static long
+mshv_unmap_user_memory(struct mshv_partition *partition,
+		       struct mshv_user_mem_region *mem)
+{
+	struct mshv_mem_region *region;
+
+	if (!(mem->flags & BIT(MSHV_SET_MEM_BIT_UNMAP)))
+		return -EINVAL;
+
+	spin_lock(&partition->pt_mem_regions_lock);
+
+	region = mshv_partition_region_by_gfn(partition, mem->guest_pfn);
+	if (!region) {
+		spin_unlock(&partition->pt_mem_regions_lock);
+		return -ENOENT;
+	}
+
+	/* Paranoia check */
+	if (region->start_uaddr != mem->userspace_addr ||
+	    region->start_gfn != mem->guest_pfn ||
+	    region->nr_pages != HVPFN_DOWN(mem->size)) {
+		spin_unlock(&partition->pt_mem_regions_lock);
+		return -EINVAL;
+	}
+
+	hlist_del(&region->hnode);
+
+	spin_unlock(&partition->pt_mem_regions_lock);
+
+	mshv_region_put(region);
+
+	return 0;
+}
+
+static long
+mshv_partition_ioctl_set_memory(struct mshv_partition *partition,
+				struct mshv_user_mem_region __user *user_mem)
+{
+	struct mshv_user_mem_region mem;
+
+	if (copy_from_user(&mem, user_mem, sizeof(mem)))
+		return -EFAULT;
+
+	if (!mem.size ||
+	    !PAGE_ALIGNED(mem.size) ||
+	    !PAGE_ALIGNED(mem.userspace_addr) ||
+	    (mem.flags & ~MSHV_SET_MEM_FLAGS_MASK) ||
+	    mshv_field_nonzero(mem, rsvd))
+		return -EINVAL;
+
+	if (mem.flags & BIT(MSHV_SET_MEM_BIT_UNMAP))
+		return mshv_unmap_user_memory(partition, &mem);
+
+	return mshv_map_user_memory(partition, &mem);
+}
+
+static long
+mshv_partition_ioctl_ioeventfd(struct mshv_partition *partition,
+			       void __user *user_args)
+{
+	struct mshv_user_ioeventfd args;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	return mshv_set_unset_ioeventfd(partition, &args);
+}
+
+static long
+mshv_partition_ioctl_irqfd(struct mshv_partition *partition,
+			   void __user *user_args)
+{
+	struct mshv_user_irqfd args;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	return mshv_set_unset_irqfd(partition, &args);
+}
+
+static long
+mshv_partition_ioctl_get_gpap_access_bitmap(struct mshv_partition *partition,
+					    void __user *user_args)
+{
+	struct mshv_gpap_access_bitmap args;
+	union hv_gpa_page_access_state *states;
+	long ret, i;
+	union hv_gpa_page_access_state_flags hv_flags = {};
+	u8 hv_type_mask;
+	ulong bitmap_buf_sz, states_buf_sz;
+	int written = 0;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	if (args.access_type >= MSHV_GPAP_ACCESS_TYPE_COUNT ||
+	    args.access_op >= MSHV_GPAP_ACCESS_OP_COUNT ||
+	    mshv_field_nonzero(args, rsvd) || !args.page_count ||
+	    !args.bitmap_ptr)
+		return -EINVAL;
+
+	if (check_mul_overflow(args.page_count, sizeof(*states), &states_buf_sz))
+		return -E2BIG;
+
+	/* Num bytes needed to store bitmap; one bit per page rounded up */
+	bitmap_buf_sz = DIV_ROUND_UP(args.page_count, 8);
+
+	/* Sanity check */
+	if (bitmap_buf_sz > states_buf_sz)
+		return -EBADFD;
+
+	switch (args.access_type) {
+	case MSHV_GPAP_ACCESS_TYPE_ACCESSED:
+		hv_type_mask = 1;
+		if (args.access_op == MSHV_GPAP_ACCESS_OP_CLEAR) {
+			hv_flags.clear_accessed = 1;
+			/* not accessed implies not dirty */
+			hv_flags.clear_dirty = 1;
+		} else { /* MSHV_GPAP_ACCESS_OP_SET */
+			hv_flags.set_accessed = 1;
+		}
+		break;
+	case MSHV_GPAP_ACCESS_TYPE_DIRTY:
+		hv_type_mask = 2;
+		if (args.access_op == MSHV_GPAP_ACCESS_OP_CLEAR) {
+			hv_flags.clear_dirty = 1;
+		} else { /* MSHV_GPAP_ACCESS_OP_SET */
+			hv_flags.set_dirty = 1;
+			/* dirty implies accessed */
+			hv_flags.set_accessed = 1;
+		}
+		break;
+	}
+
+	states = vzalloc(states_buf_sz);
+	if (!states)
+		return -ENOMEM;
+
+	ret = hv_call_get_gpa_access_states(partition->pt_id, args.page_count,
+					    args.gpap_base, hv_flags, &written,
+					    states);
+	if (ret)
+		goto free_return;
+
+	/*
+	 * Overwrite states buffer with bitmap - the bits in hv_type_mask
+	 * correspond to bitfields in hv_gpa_page_access_state
+	 */
+	for (i = 0; i < written; ++i)
+		__assign_bit(i, (ulong *)states,
+			     states[i].as_uint8 & hv_type_mask);
+
+	/* zero the unused bits in the last byte(s) of the returned bitmap */
+	for (i = written; i < bitmap_buf_sz * 8; ++i)
+		__clear_bit(i, (ulong *)states);
+
+	if (copy_to_user((void __user *)args.bitmap_ptr, states, bitmap_buf_sz))
+		ret = -EFAULT;
+
+free_return:
+	vfree(states);
+	return ret;
+}
+
+static long
+mshv_partition_ioctl_set_msi_routing(struct mshv_partition *partition,
+				     void __user *user_args)
+{
+	struct mshv_user_irq_entry *entries = NULL;
+	struct mshv_user_irq_table args;
+	long ret;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	if (args.nr > MSHV_MAX_GUEST_IRQS ||
+	    mshv_field_nonzero(args, rsvd))
+		return -EINVAL;
+
+	if (args.nr) {
+		struct mshv_user_irq_table __user *urouting = user_args;
+
+		entries = vmemdup_user(urouting->entries,
+				       array_size(sizeof(*entries),
+						  args.nr));
+		if (IS_ERR(entries))
+			return PTR_ERR(entries);
+	}
+	ret = mshv_update_routing_table(partition, entries, args.nr);
+	kvfree(entries);
+
+	return ret;
+}
+
+static long
+mshv_partition_ioctl_initialize(struct mshv_partition *partition)
+{
+	long ret;
+
+	if (partition->pt_initialized)
+		return 0;
+
+	ret = hv_call_initialize_partition(partition->pt_id);
+	if (ret)
+		goto withdraw_mem;
+
+	ret = mshv_debugfs_partition_create(partition);
+	if (ret)
+		goto finalize_partition;
+
+	partition->pt_initialized = true;
+
+	return 0;
+
+finalize_partition:
+	hv_call_finalize_partition(partition->pt_id);
+withdraw_mem:
+	hv_call_withdraw_memory(U64_MAX, NUMA_NO_NODE, partition->pt_id);
+
+	return ret;
+}
+
+static long
+mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	struct mshv_partition *partition = filp->private_data;
+	long ret;
+	void __user *uarg = (void __user *)arg;
+
+	if (mutex_lock_killable(&partition->pt_mutex))
+		return -EINTR;
+
+	switch (ioctl) {
+	case MSHV_INITIALIZE_PARTITION:
+		ret = mshv_partition_ioctl_initialize(partition);
+		break;
+	case MSHV_SET_GUEST_MEMORY:
+		ret = mshv_partition_ioctl_set_memory(partition, uarg);
+		break;
+	case MSHV_CREATE_VP:
+		ret = mshv_partition_ioctl_create_vp(partition, uarg);
+		break;
+	case MSHV_IRQFD:
+		ret = mshv_partition_ioctl_irqfd(partition, uarg);
+		break;
+	case MSHV_IOEVENTFD:
+		ret = mshv_partition_ioctl_ioeventfd(partition, uarg);
+		break;
+	case MSHV_SET_MSI_ROUTING:
+		ret = mshv_partition_ioctl_set_msi_routing(partition, uarg);
+		break;
+	case MSHV_GET_GPAP_ACCESS_BITMAP:
+		ret = mshv_partition_ioctl_get_gpap_access_bitmap(partition,
+								  uarg);
+		break;
+	case MSHV_ROOT_HVCALL:
+		ret = mshv_ioctl_passthru_hvcall(partition, true, uarg);
+		break;
+	default:
+		ret = -ENOTTY;
+	}
+
+	mutex_unlock(&partition->pt_mutex);
+	return ret;
+}
+
+static int
+disable_vp_dispatch(struct mshv_vp *vp)
+{
+	int ret;
+	struct hv_register_assoc dispatch_suspend = {
+		.name = HV_REGISTER_DISPATCH_SUSPEND,
+		.value.dispatch_suspend.suspended = 1,
+	};
+
+	ret = mshv_set_vp_registers(vp->vp_index, vp->vp_partition->pt_id,
+				    1, &dispatch_suspend);
+	if (ret)
+		vp_err(vp, "failed to suspend\n");
+
+	trace_mshv_disable_vp_dispatch(vp->vp_partition->pt_id,
+				       vp->vp_index, ret);
+
+	return ret;
+}
+
+static int
+get_vp_signaled_count(struct mshv_vp *vp, u64 *count)
+{
+	int ret;
+	struct hv_register_assoc root_signal_count = {
+		.name = HV_REGISTER_VP_ROOT_SIGNAL_COUNT,
+	};
+
+	ret = mshv_get_vp_registers(vp->vp_index, vp->vp_partition->pt_id,
+				    1, &root_signal_count);
+
+	if (ret) {
+		vp_err(vp, "Failed to get root signal count");
+		*count = 0;
+		return ret;
+	}
+
+	*count = root_signal_count.value.reg64;
+
+	return ret;
+}
+
+static void
+drain_vp_signals(struct mshv_vp *vp)
+{
+	u64 hv_signal_count;
+	u64 vp_signal_count;
+
+	get_vp_signaled_count(vp, &hv_signal_count);
+
+	vp_signal_count = atomic64_read(&vp->run.vp_signaled_count);
+
+	/*
+	 * There should be at most 1 outstanding notification, but be extra
+	 * careful anyway.
+	 */
+	while (hv_signal_count != vp_signal_count) {
+		WARN_ON(hv_signal_count - vp_signal_count != 1);
+
+		if (wait_event_interruptible(vp->run.vp_suspend_queue,
+					     vp->run.kicked_by_hv == 1))
+			break;
+		vp->run.kicked_by_hv = 0;
+		vp_signal_count = atomic64_read(&vp->run.vp_signaled_count);
+	}
+
+	trace_mshv_drain_vp_signals(vp->vp_partition->pt_id, vp->vp_index);
+}
+
+static void drain_all_vps(const struct mshv_partition *partition)
+{
+	int i;
+	struct mshv_vp *vp;
+
+	/*
+	 * VPs are reachable from ISR. It is safe to not take the partition
+	 * lock because nobody else can enter this function and drop the
+	 * partition from the list.
+	 */
+	for (i = 0; i < MSHV_MAX_VPS; i++) {
+		vp = partition->pt_vp_array[i];
+		if (!vp)
+			continue;
+		/*
+		 * Disable dispatching of the VP in the hypervisor. After this
+		 * the hypervisor guarantees it won't generate any signals for
+		 * the VP and the hypervisor's VP signal count won't change.
+		 */
+		disable_vp_dispatch(vp);
+		drain_vp_signals(vp);
+	}
+}
+
+static void
+remove_partition(struct mshv_partition *partition)
+{
+	spin_lock(&mshv_root.pt_ht_lock);
+	hlist_del_rcu(&partition->pt_hnode);
+	spin_unlock(&mshv_root.pt_ht_lock);
+
+	synchronize_rcu();
+}
+
+/*
+ * Tear down a partition and remove it from the list.
+ * Partition's refcount must be 0
+ */
+static void destroy_partition(struct mshv_partition *partition)
+{
+	struct mshv_vp *vp;
+	struct mshv_mem_region *region;
+	struct hlist_node *n;
+	int i;
+
+	if (refcount_read(&partition->pt_ref_count)) {
+		pt_err(partition,
+		       "Attempt to destroy partition but refcount > 0\n");
+		return;
+	}
+
+	trace_mshv_destroy_partition(partition->pt_id);
+
+	if (partition->pt_initialized) {
+		/*
+		 * We only need to drain signals for root scheduler. This should be
+		 * done before removing the partition from the partition list.
+		 */
+		if (hv_scheduler_type == HV_SCHEDULER_TYPE_ROOT)
+			drain_all_vps(partition);
+
+		/* Remove vps */
+		for (i = 0; i < MSHV_MAX_VPS; ++i) {
+			vp = partition->pt_vp_array[i];
+			if (!vp)
+				continue;
+
+			mshv_debugfs_vp_remove(vp);
+			mshv_vp_stats_unmap(partition->pt_id, vp->vp_index,
+					    vp->vp_stats_pages);
+
+			if (vp->vp_register_page) {
+				(void)hv_unmap_vp_state_page(partition->pt_id,
+							     vp->vp_index,
+							     HV_VP_STATE_PAGE_REGISTERS,
+							     virt_to_page(vp->vp_register_page),
+							     input_vtl_zero);
+				vp->vp_register_page = NULL;
+			}
+
+			(void)hv_unmap_vp_state_page(partition->pt_id,
+						     vp->vp_index,
+						     HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
+						     virt_to_page(vp->vp_intercept_msg_page),
+						     input_vtl_zero);
+			vp->vp_intercept_msg_page = NULL;
+
+			if (vp->vp_ghcb_page) {
+				(void)hv_unmap_vp_state_page(partition->pt_id,
+							     vp->vp_index,
+							     HV_VP_STATE_PAGE_GHCB,
+							     virt_to_page(vp->vp_ghcb_page),
+							     input_vtl_normal);
+				vp->vp_ghcb_page = NULL;
+			}
+
+			kfree(vp);
+
+			partition->pt_vp_array[i] = NULL;
+		}
+
+		mshv_debugfs_partition_remove(partition);
+
+		/* Deallocates and unmaps everything including vcpus, GPA mappings etc */
+		hv_call_finalize_partition(partition->pt_id);
+
+		partition->pt_initialized = false;
+	}
+
+	remove_partition(partition);
+
+	hlist_for_each_entry_safe(region, n, &partition->pt_mem_regions,
+				  hnode) {
+		hlist_del(&region->hnode);
+		mshv_region_put(region);
+	}
+
+	/* Withdraw and free all pages we deposited */
+	hv_call_withdraw_memory(U64_MAX, NUMA_NO_NODE, partition->pt_id);
+	hv_call_delete_partition(partition->pt_id);
+
+	mshv_free_routing_table(partition);
+	kfree(partition);
+}
+
+struct
+mshv_partition *mshv_partition_get(struct mshv_partition *partition)
+{
+	if (refcount_inc_not_zero(&partition->pt_ref_count))
+		return partition;
+	return NULL;
+}
+
+struct
+mshv_partition *mshv_partition_find(u64 partition_id)
+	__must_hold(RCU)
+{
+	struct mshv_partition *p;
+
+	hash_for_each_possible_rcu(mshv_root.pt_htable, p, pt_hnode,
+				   partition_id)
+		if (p->pt_id == partition_id)
+			return p;
+
+	return NULL;
+}
+
+void
+mshv_partition_put(struct mshv_partition *partition)
+{
+	if (refcount_dec_and_test(&partition->pt_ref_count))
+		destroy_partition(partition);
+}
+
+static int
+mshv_partition_release(struct inode *inode, struct file *filp)
+{
+	struct mshv_partition *partition = filp->private_data;
+
+	trace_mshv_partition_release(partition->pt_id);
+
+	mshv_eventfd_release(partition);
+
+	cleanup_srcu_struct(&partition->pt_irq_srcu);
+
+	mshv_partition_put(partition);
+
+	return 0;
+}
+
+static int
+add_partition(struct mshv_partition *partition)
+{
+	spin_lock(&mshv_root.pt_ht_lock);
+
+	hash_add_rcu(mshv_root.pt_htable, &partition->pt_hnode,
+		     partition->pt_id);
+
+	spin_unlock(&mshv_root.pt_ht_lock);
+
+	return 0;
+}
+
+static_assert(MSHV_NUM_CPU_FEATURES_BANKS ==
+	      HV_PARTITION_PROCESSOR_FEATURES_BANKS);
+
+static long mshv_ioctl_process_pt_flags(void __user *user_arg, u64 *pt_flags,
+					struct hv_partition_creation_properties *cr_props,
+					union hv_partition_isolation_properties *isol_props)
+{
+	int i;
+	struct mshv_create_partition_v2 args;
+	union hv_partition_processor_features *disabled_procs;
+	union hv_partition_processor_xsave_features *disabled_xsave;
+
+	/* First, copy v1 struct in case user is on previous versions */
+	if (copy_from_user(&args, user_arg,
+			   sizeof(struct mshv_create_partition)))
+		return -EFAULT;
+
+	if ((args.pt_flags & ~MSHV_PT_FLAGS_MASK) ||
+	    args.pt_isolation >= MSHV_PT_ISOLATION_COUNT)
+		return -EINVAL;
+
+	disabled_procs = &cr_props->disabled_processor_features;
+	disabled_xsave = &cr_props->disabled_processor_xsave_features;
+
+	/* Check if user provided newer struct with feature fields */
+	if (args.pt_flags & BIT_ULL(MSHV_PT_BIT_CPU_AND_XSAVE_FEATURES)) {
+		if (copy_from_user(&args, user_arg, sizeof(args)))
+			return -EFAULT;
+
+		/* Re-validate v1 fields after second copy_from_user() */
+		if ((args.pt_flags & ~MSHV_PT_FLAGS_MASK) ||
+		    args.pt_isolation >= MSHV_PT_ISOLATION_COUNT)
+			return -EINVAL;
+
+		if (args.pt_num_cpu_fbanks != MSHV_NUM_CPU_FEATURES_BANKS ||
+		    mshv_field_nonzero(args, pt_rsvd) ||
+		    mshv_field_nonzero(args, pt_rsvd1))
+			return -EINVAL;
+
+		/*
+		 * Note this assumes MSHV_NUM_CPU_FEATURES_BANKS will never
+		 * change and equals HV_PARTITION_PROCESSOR_FEATURES_BANKS
+		 * (i.e. 2).
+		 *
+		 * Further banks (index >= 2) will be modifiable as 'early'
+		 * properties via the set partition property hypercall.
+		 */
+		for (i = 0; i < HV_PARTITION_PROCESSOR_FEATURES_BANKS; i++)
+			disabled_procs->as_uint64[i] = args.pt_cpu_fbanks[i];
+
+#if IS_ENABLED(CONFIG_X86_64)
+		disabled_xsave->as_uint64 = args.pt_disabled_xsave;
+#else
+		/*
+		 * In practice this field is ignored on arm64, but safer to
+		 * zero it in case it is ever used.
+		 */
+		disabled_xsave->as_uint64 = 0;
+
+		if (mshv_field_nonzero(args, pt_rsvd2))
+			return -EINVAL;
+#endif
+	} else {
+		/*
+		 * v1 behavior: try to enable everything. The hypervisor will
+		 * disable features that are not supported. The banks can be
+		 * queried via the get partition property hypercall.
+		 */
+		for (i = 0; i < HV_PARTITION_PROCESSOR_FEATURES_BANKS; i++)
+			disabled_procs->as_uint64[i] = 0;
+
+		disabled_xsave->as_uint64 = 0;
+	}
+
+	/* Only support EXO partitions */
+	*pt_flags = HV_PARTITION_CREATION_FLAG_EXO_PARTITION |
+		    HV_PARTITION_CREATION_FLAG_INTERCEPT_MESSAGE_PAGE_ENABLED;
+
+	if (args.pt_flags & BIT_ULL(MSHV_PT_BIT_LAPIC))
+		*pt_flags |= HV_PARTITION_CREATION_FLAG_LAPIC_ENABLED;
+	if (args.pt_flags & BIT_ULL(MSHV_PT_BIT_X2APIC))
+		*pt_flags |= HV_PARTITION_CREATION_FLAG_X2APIC_CAPABLE;
+	if (args.pt_flags & BIT_ULL(MSHV_PT_BIT_GPA_SUPER_PAGES))
+		*pt_flags |= HV_PARTITION_CREATION_FLAG_GPA_SUPER_PAGES_ENABLED;
+	if (args.pt_flags & BIT(MSHV_PT_BIT_NESTED_VIRTUALIZATION))
+		*pt_flags |= HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE;
+	if (args.pt_flags & BIT(MSHV_PT_BIT_SMT_ENABLED_GUEST))
+		*pt_flags |= HV_PARTITION_CREATION_FLAG_SMT_ENABLED_GUEST;
+
+	isol_props->as_uint64 = 0;
+
+	switch (args.pt_isolation) {
+	case MSHV_PT_ISOLATION_NONE:
+		isol_props->isolation_type = HV_PARTITION_ISOLATION_TYPE_NONE;
+		break;
+	}
+
+	return 0;
+}
+
+static long
+mshv_ioctl_create_partition(void __user *user_arg, struct device *module_dev)
+{
+	u64 creation_flags;
+	struct hv_partition_creation_properties creation_properties;
+	union hv_partition_isolation_properties isolation_properties;
+	struct mshv_partition *partition;
+	u64 pt_id = -1;
+	long ret;
+
+	ret = mshv_ioctl_process_pt_flags(user_arg, &creation_flags,
+					  &creation_properties,
+					  &isolation_properties);
+	if (ret)
+		return ret;
+
+	partition = kzalloc_obj(*partition);
+	if (!partition)
+		return -ENOMEM;
+
+	partition->pt_module_dev = module_dev;
+	partition->isolation_type = isolation_properties.isolation_type;
+
+	refcount_set(&partition->pt_ref_count, 1);
+
+	mutex_init(&partition->pt_mutex);
+
+	mutex_init(&partition->pt_irq_lock);
+
+	init_completion(&partition->async_hypercall);
+
+	INIT_HLIST_HEAD(&partition->irq_ack_notifier_list);
+
+	INIT_HLIST_HEAD(&partition->pt_devices);
+
+	spin_lock_init(&partition->pt_mem_regions_lock);
+	INIT_HLIST_HEAD(&partition->pt_mem_regions);
+
+	mshv_eventfd_init(partition);
+
+	ret = init_srcu_struct(&partition->pt_irq_srcu);
+	if (ret)
+		goto free_partition;
+
+	ret = hv_call_create_partition(creation_flags,
+				       creation_properties,
+				       isolation_properties,
+				       &pt_id);
+	if (ret)
+		goto cleanup_irq_srcu;
+
+	partition->pt_id = pt_id;
+
+	ret = add_partition(partition);
+	if (ret)
+		goto delete_partition;
+
+	ret = mshv_init_async_handler(partition);
+	if (ret)
+		goto remove_partition;
+
+	ret = FD_ADD(O_CLOEXEC, anon_inode_getfile("mshv_partition",
+						   &mshv_partition_fops,
+						   partition, O_RDWR));
+	if (ret < 0)
+		goto remove_partition;
+
+	goto out;
+
+remove_partition:
+	remove_partition(partition);
+delete_partition:
+	hv_call_delete_partition(partition->pt_id);
+cleanup_irq_srcu:
+	cleanup_srcu_struct(&partition->pt_irq_srcu);
+free_partition:
+	kfree(partition);
+out:
+	trace_mshv_create_partition(pt_id, ret);
+	return ret;
+}
+
+static long mshv_dev_ioctl(struct file *filp, unsigned int ioctl,
+			   unsigned long arg)
+{
+	struct miscdevice *misc = filp->private_data;
+
+	switch (ioctl) {
+	case MSHV_CREATE_PARTITION:
+		return mshv_ioctl_create_partition((void __user *)arg,
+						misc->this_device);
+	case MSHV_ROOT_HVCALL:
+		return mshv_ioctl_passthru_hvcall(NULL, false,
+					(void __user *)arg);
+	}
+
+	return -ENOTTY;
+}
+
+static int
+mshv_dev_open(struct inode *inode, struct file *filp)
+{
+	return 0;
+}
+
+static int
+mshv_dev_release(struct inode *inode, struct file *filp)
+{
+	return 0;
+}
+
+static int mshv_root_sched_online;
+
+static const char *scheduler_type_to_string(enum hv_scheduler_type type)
+{
+	switch (type) {
+	case HV_SCHEDULER_TYPE_LP:
+		return "classic scheduler without SMT";
+	case HV_SCHEDULER_TYPE_LP_SMT:
+		return "classic scheduler with SMT";
+	case HV_SCHEDULER_TYPE_CORE_SMT:
+		return "core scheduler";
+	case HV_SCHEDULER_TYPE_ROOT:
+		return "root scheduler";
+	default:
+		return "unknown scheduler";
+	};
+}
+
+static int __init l1vh_retrieve_scheduler_type(enum hv_scheduler_type *out)
+{
+	u64 integrated_sched_enabled;
+	int ret;
+
+	*out = HV_SCHEDULER_TYPE_CORE_SMT;
+
+	if (!mshv_root.vmm_caps.vmm_enable_integrated_scheduler)
+		return 0;
+
+	ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF,
+						HV_PARTITION_PROPERTY_INTEGRATED_SCHEDULER_ENABLED,
+						0, &integrated_sched_enabled,
+						sizeof(integrated_sched_enabled));
+	if (ret)
+		return ret;
+
+	if (integrated_sched_enabled)
+		*out = HV_SCHEDULER_TYPE_ROOT;
+
+	return 0;
+}
+
+/* TODO move this to hv_common.c when needed outside */
+static int __init hv_retrieve_scheduler_type(enum hv_scheduler_type *out)
+{
+	struct hv_input_get_system_property *input;
+	struct hv_output_get_system_property *output;
+	unsigned long flags;
+	u64 status;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+
+	memset(input, 0, sizeof(*input));
+	memset(output, 0, sizeof(*output));
+	input->property_id = HV_SYSTEM_PROPERTY_SCHEDULER_TYPE;
+
+	status = hv_do_hypercall(HVCALL_GET_SYSTEM_PROPERTY, input, output);
+	if (!hv_result_success(status)) {
+		local_irq_restore(flags);
+		pr_err("%s: %s\n", __func__, hv_result_to_string(status));
+		return hv_result_to_errno(status);
+	}
+
+	*out = output->scheduler_type;
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+/* Retrieve and stash the supported scheduler type */
+static int __init mshv_retrieve_scheduler_type(struct device *dev)
+{
+	int ret;
+
+	if (hv_l1vh_partition())
+		ret = l1vh_retrieve_scheduler_type(&hv_scheduler_type);
+	else
+		ret = hv_retrieve_scheduler_type(&hv_scheduler_type);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "Hypervisor using %s\n",
+		 scheduler_type_to_string(hv_scheduler_type));
+
+	switch (hv_scheduler_type) {
+	case HV_SCHEDULER_TYPE_CORE_SMT:
+	case HV_SCHEDULER_TYPE_LP_SMT:
+	case HV_SCHEDULER_TYPE_ROOT:
+	case HV_SCHEDULER_TYPE_LP:
+		/* Supported scheduler, nothing to do */
+		break;
+	default:
+		dev_err(dev, "unsupported scheduler 0x%x, bailing.\n",
+			hv_scheduler_type);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int mshv_root_scheduler_init(unsigned int cpu)
+{
+	void **inputarg, **outputarg, *p;
+
+	inputarg = (void **)this_cpu_ptr(root_scheduler_input);
+	outputarg = (void **)this_cpu_ptr(root_scheduler_output);
+
+	/* Allocate two consecutive pages. One for input, one for output. */
+	p = kmalloc_array(2, HV_HYP_PAGE_SIZE, GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	*inputarg = p;
+	*outputarg = (char *)p + HV_HYP_PAGE_SIZE;
+
+	return 0;
+}
+
+static int mshv_root_scheduler_cleanup(unsigned int cpu)
+{
+	void *p, **inputarg, **outputarg;
+
+	inputarg = (void **)this_cpu_ptr(root_scheduler_input);
+	outputarg = (void **)this_cpu_ptr(root_scheduler_output);
+
+	p = *inputarg;
+
+	*inputarg = NULL;
+	*outputarg = NULL;
+
+	kfree(p);
+
+	return 0;
+}
+
+/* Must be called after retrieving the scheduler type */
+static int
+root_scheduler_init(struct device *dev)
+{
+	int ret;
+
+	if (hv_scheduler_type != HV_SCHEDULER_TYPE_ROOT)
+		return 0;
+
+	root_scheduler_input = alloc_percpu(void *);
+	root_scheduler_output = alloc_percpu(void *);
+
+	if (!root_scheduler_input || !root_scheduler_output) {
+		dev_err(dev, "Failed to allocate root scheduler buffers\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_root_sched",
+				mshv_root_scheduler_init,
+				mshv_root_scheduler_cleanup);
+
+	if (ret < 0) {
+		dev_err(dev, "Failed to setup root scheduler state: %i\n", ret);
+		goto out;
+	}
+
+	mshv_root_sched_online = ret;
+
+	return 0;
+
+out:
+	free_percpu(root_scheduler_input);
+	free_percpu(root_scheduler_output);
+	return ret;
+}
+
+static void
+root_scheduler_deinit(void)
+{
+	if (hv_scheduler_type != HV_SCHEDULER_TYPE_ROOT)
+		return;
+
+	cpuhp_remove_state(mshv_root_sched_online);
+	free_percpu(root_scheduler_input);
+	free_percpu(root_scheduler_output);
+}
+
+static int __init mshv_init_vmm_caps(struct device *dev)
+{
+	int ret;
+
+	ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF,
+						HV_PARTITION_PROPERTY_VMM_CAPABILITIES,
+						0, &mshv_root.vmm_caps,
+						sizeof(mshv_root.vmm_caps));
+	if (ret && hv_l1vh_partition()) {
+		dev_err(dev, "Failed to get VMM capabilities: %d\n", ret);
+		return ret;
+	}
+
+	dev_dbg(dev, "vmm_caps = %#llx\n", mshv_root.vmm_caps.as_uint64[0]);
+
+	return 0;
+}
+
+static int __init mshv_parent_partition_init(void)
+{
+	int ret;
+	struct device *dev;
+	union hv_hypervisor_version_info version_info;
+
+	if (!hv_parent_partition() || is_kdump_kernel())
+		return -ENODEV;
+
+	if (hv_get_hypervisor_version(&version_info))
+		return -ENODEV;
+
+	ret = misc_register(&mshv_dev);
+	if (ret)
+		return ret;
+
+	dev = mshv_dev.this_device;
+
+	if (version_info.build_number < MSHV_HV_MIN_VERSION ||
+	    version_info.build_number > MSHV_HV_MAX_VERSION) {
+		dev_err(dev, "Running on unvalidated Hyper-V version\n");
+		dev_err(dev, "Versions: current: %u  min: %u  max: %u\n",
+			version_info.build_number, MSHV_HV_MIN_VERSION,
+			MSHV_HV_MAX_VERSION);
+	}
+
+	ret = mshv_synic_init(dev);
+	if (ret)
+		goto device_deregister;
+
+	ret = mshv_init_vmm_caps(dev);
+	if (ret)
+		goto synic_cleanup;
+
+	ret = mshv_retrieve_scheduler_type(dev);
+	if (ret)
+		goto synic_cleanup;
+
+	ret = root_scheduler_init(dev);
+	if (ret)
+		goto synic_cleanup;
+
+	ret = mshv_debugfs_init();
+	if (ret)
+		goto deinit_root_scheduler;
+
+	ret = mshv_irqfd_wq_init();
+	if (ret)
+		goto exit_debugfs;
+
+	spin_lock_init(&mshv_root.pt_ht_lock);
+	hash_init(mshv_root.pt_htable);
+
+	hv_setup_mshv_handler(mshv_isr);
+
+	return 0;
+
+exit_debugfs:
+	mshv_debugfs_exit();
+deinit_root_scheduler:
+	root_scheduler_deinit();
+synic_cleanup:
+	mshv_synic_exit();
+device_deregister:
+	misc_deregister(&mshv_dev);
+	return ret;
+}
+
+static void __exit mshv_parent_partition_exit(void)
+{
+	hv_setup_mshv_handler(NULL);
+	mshv_port_table_fini();
+	mshv_debugfs_exit();
+	misc_deregister(&mshv_dev);
+	mshv_irqfd_wq_cleanup();
+	root_scheduler_deinit();
+	mshv_synic_exit();
+}
+
+module_init(mshv_parent_partition_init);
+module_exit(mshv_parent_partition_exit);
diff --git a/drivers/hv/mshv_synic.c b/drivers/hv/mshv_synic.c
new file mode 100644
index 000000000..7c168e5a7
--- /dev/null
+++ b/drivers/hv/mshv_synic.c
@@ -0,0 +1,873 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ *
+ * mshv_root module's main interrupt handler and associated functionality.
+ *
+ * Authors: Microsoft Linux virtualization team
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/cpuhotplug.h>
+#include <linux/hyperv.h>
+#include <linux/reboot.h>
+#include <asm/mshyperv.h>
+#include <linux/acpi.h>
+
+#include "mshv_eventfd.h"
+#include "mshv.h"
+
+static int synic_cpuhp_online;
+static struct hv_synic_pages __percpu *synic_pages;
+static int mshv_sint_vector = -1; /* hwirq for the SynIC SINTs */
+static int mshv_sint_irq = -1; /* Linux IRQ for mshv_sint_vector */
+
+static u32 synic_event_ring_get_queued_port(u32 sint_index)
+{
+	struct hv_synic_event_ring_page **event_ring_page;
+	volatile struct hv_synic_event_ring *ring;
+	struct hv_synic_pages *spages;
+	u8 **synic_eventring_tail;
+	u32 message;
+	u8 tail;
+
+	spages = this_cpu_ptr(synic_pages);
+	event_ring_page = &spages->synic_event_ring_page;
+	synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
+
+	if (unlikely(!*synic_eventring_tail)) {
+		pr_debug("Missing synic event ring tail!\n");
+		return 0;
+	}
+	tail = (*synic_eventring_tail)[sint_index];
+
+	if (unlikely(!*event_ring_page)) {
+		pr_debug("Missing synic event ring page!\n");
+		return 0;
+	}
+
+	ring = &(*event_ring_page)->sint_event_ring[sint_index];
+
+	/*
+	 * Get the message.
+	 */
+	message = ring->data[tail];
+
+	if (!message) {
+		if (ring->ring_full) {
+			/*
+			 * Ring is marked full, but we would have consumed all
+			 * the messages. Notify the hypervisor that ring is now
+			 * empty and check again.
+			 */
+			ring->ring_full = 0;
+			hv_call_notify_port_ring_empty(sint_index);
+			message = ring->data[tail];
+		}
+
+		if (!message) {
+			ring->signal_masked = 0;
+			/*
+			 * Unmask the signal and sync with hypervisor
+			 * before one last check for any message.
+			 */
+			mb();
+			message = ring->data[tail];
+
+			/*
+			 * Ok, lets bail out.
+			 */
+			if (!message)
+				return 0;
+		}
+
+		ring->signal_masked = 1;
+	}
+
+	/*
+	 * Clear the message in the ring buffer.
+	 */
+	ring->data[tail] = 0;
+
+	if (++tail == HV_SYNIC_EVENT_RING_MESSAGE_COUNT)
+		tail = 0;
+
+	(*synic_eventring_tail)[sint_index] = tail;
+
+	return message;
+}
+
+static bool
+mshv_doorbell_isr(struct hv_message *msg)
+{
+	struct hv_notification_message_payload *notification;
+	u32 port;
+
+	if (msg->header.message_type != HVMSG_SYNIC_SINT_INTERCEPT)
+		return false;
+
+	notification = (struct hv_notification_message_payload *)msg->u.payload;
+	if (notification->sint_index != HV_SYNIC_DOORBELL_SINT_INDEX)
+		return false;
+
+	while ((port = synic_event_ring_get_queued_port(HV_SYNIC_DOORBELL_SINT_INDEX))) {
+		struct port_table_info ptinfo = { 0 };
+
+		if (mshv_portid_lookup(port, &ptinfo)) {
+			pr_debug("Failed to get port info from port_table!\n");
+			continue;
+		}
+
+		if (ptinfo.hv_port_type != HV_PORT_TYPE_DOORBELL) {
+			pr_debug("Not a doorbell port!, port: %d, port_type: %d\n",
+				 port, ptinfo.hv_port_type);
+			continue;
+		}
+
+		/* Invoke the callback */
+		ptinfo.hv_port_doorbell.doorbell_cb(port,
+						 ptinfo.hv_port_doorbell.data);
+	}
+
+	return true;
+}
+
+static bool mshv_async_call_completion_isr(struct hv_message *msg)
+{
+	bool handled = false;
+	struct hv_async_completion_message_payload *async_msg;
+	struct mshv_partition *partition;
+	u64 partition_id;
+
+	if (msg->header.message_type != HVMSG_ASYNC_CALL_COMPLETION)
+		goto out;
+
+	async_msg =
+		(struct hv_async_completion_message_payload *)msg->u.payload;
+
+	partition_id = async_msg->partition_id;
+
+	/*
+	 * Hold this lock for the rest of the isr, because the partition could
+	 * be released anytime.
+	 * e.g. the MSHV_RUN_VP thread could wake on another cpu; it could
+	 * release the partition unless we hold this!
+	 */
+	rcu_read_lock();
+
+	partition = mshv_partition_find(partition_id);
+
+	if (unlikely(!partition)) {
+		pr_debug("failed to find partition %llu\n", partition_id);
+		goto unlock_out;
+	}
+
+	partition->async_hypercall_status = async_msg->status;
+	complete(&partition->async_hypercall);
+
+	handled = true;
+
+unlock_out:
+	rcu_read_unlock();
+out:
+	return handled;
+}
+
+static void kick_vp(struct mshv_vp *vp)
+{
+	atomic64_inc(&vp->run.vp_signaled_count);
+	vp->run.kicked_by_hv = 1;
+	wake_up(&vp->run.vp_suspend_queue);
+}
+
+static void
+handle_bitset_message(const struct hv_vp_signal_bitset_scheduler_message *msg)
+{
+	int bank_idx, vps_signaled = 0, bank_mask_size;
+	struct mshv_partition *partition;
+	const struct hv_vpset *vpset;
+	const u64 *bank_contents;
+	u64 partition_id = msg->partition_id;
+
+	if (msg->vp_bitset.bitset.format != HV_GENERIC_SET_SPARSE_4K) {
+		pr_debug("scheduler message format is not HV_GENERIC_SET_SPARSE_4K");
+		return;
+	}
+
+	if (msg->vp_count == 0) {
+		pr_debug("scheduler message with no VP specified");
+		return;
+	}
+
+	rcu_read_lock();
+
+	partition = mshv_partition_find(partition_id);
+	if (unlikely(!partition)) {
+		pr_debug("failed to find partition %llu\n", partition_id);
+		goto unlock_out;
+	}
+
+	vpset = &msg->vp_bitset.bitset;
+
+	bank_idx = -1;
+	bank_contents = vpset->bank_contents;
+	bank_mask_size = sizeof(vpset->valid_bank_mask) * BITS_PER_BYTE;
+
+	while (true) {
+		int vp_bank_idx = -1;
+		int vp_bank_size = sizeof(*bank_contents) * BITS_PER_BYTE;
+		int vp_index;
+
+		bank_idx = find_next_bit((unsigned long *)&vpset->valid_bank_mask,
+					 bank_mask_size, bank_idx + 1);
+		if (bank_idx == bank_mask_size)
+			break;
+
+		while (true) {
+			struct mshv_vp *vp;
+
+			vp_bank_idx = find_next_bit((unsigned long *)bank_contents,
+						    vp_bank_size, vp_bank_idx + 1);
+			if (vp_bank_idx == vp_bank_size)
+				break;
+
+			vp_index = (bank_idx * vp_bank_size) + vp_bank_idx;
+
+			/* This shouldn't happen, but just in case. */
+			if (unlikely(vp_index >= MSHV_MAX_VPS)) {
+				pr_debug("VP index %u out of bounds\n",
+					 vp_index);
+				goto unlock_out;
+			}
+
+			vp = partition->pt_vp_array[vp_index];
+			if (unlikely(!vp)) {
+				pr_debug("failed to find VP %u\n", vp_index);
+				goto unlock_out;
+			}
+
+			kick_vp(vp);
+			vps_signaled++;
+		}
+
+		bank_contents++;
+	}
+
+unlock_out:
+	rcu_read_unlock();
+
+	if (vps_signaled != msg->vp_count)
+		pr_debug("asked to signal %u VPs but only did %u\n",
+			 msg->vp_count, vps_signaled);
+}
+
+static void
+handle_pair_message(const struct hv_vp_signal_pair_scheduler_message *msg)
+{
+	struct mshv_partition *partition = NULL;
+	struct mshv_vp *vp;
+	int idx;
+
+	rcu_read_lock();
+
+	for (idx = 0; idx < msg->vp_count; idx++) {
+		u64 partition_id = msg->partition_ids[idx];
+		u32 vp_index = msg->vp_indexes[idx];
+
+		if (idx == 0 || partition->pt_id != partition_id) {
+			partition = mshv_partition_find(partition_id);
+			if (unlikely(!partition)) {
+				pr_debug("failed to find partition %llu\n",
+					 partition_id);
+				break;
+			}
+		}
+
+		/* This shouldn't happen, but just in case. */
+		if (unlikely(vp_index >= MSHV_MAX_VPS)) {
+			pr_debug("VP index %u out of bounds\n", vp_index);
+			break;
+		}
+
+		vp = partition->pt_vp_array[vp_index];
+		if (!vp) {
+			pr_debug("failed to find VP %u\n", vp_index);
+			break;
+		}
+
+		kick_vp(vp);
+	}
+
+	rcu_read_unlock();
+}
+
+static bool
+mshv_scheduler_isr(struct hv_message *msg)
+{
+	if (msg->header.message_type != HVMSG_SCHEDULER_VP_SIGNAL_BITSET &&
+	    msg->header.message_type != HVMSG_SCHEDULER_VP_SIGNAL_PAIR)
+		return false;
+
+	if (msg->header.message_type == HVMSG_SCHEDULER_VP_SIGNAL_BITSET)
+		handle_bitset_message((struct hv_vp_signal_bitset_scheduler_message *)
+				      msg->u.payload);
+	else
+		handle_pair_message((struct hv_vp_signal_pair_scheduler_message *)
+				    msg->u.payload);
+
+	return true;
+}
+
+static bool
+mshv_intercept_isr(struct hv_message *msg)
+{
+	struct mshv_partition *partition;
+	bool handled = false;
+	struct mshv_vp *vp;
+	u64 partition_id;
+	u32 vp_index;
+
+	partition_id = msg->header.sender;
+
+	rcu_read_lock();
+
+	partition = mshv_partition_find(partition_id);
+	if (unlikely(!partition)) {
+		pr_debug("failed to find partition %llu\n",
+			 partition_id);
+		goto unlock_out;
+	}
+
+	if (msg->header.message_type == HVMSG_X64_APIC_EOI) {
+		/*
+		 * Check if this gsi is registered in the
+		 * ack_notifier list and invoke the callback
+		 * if registered.
+		 */
+
+		/*
+		 * If there is a notifier, the ack callback is supposed
+		 * to handle the VMEXIT. So we need not pass this message
+		 * to vcpu thread.
+		 */
+		struct hv_x64_apic_eoi_message *eoi_msg =
+			(struct hv_x64_apic_eoi_message *)&msg->u.payload[0];
+
+		if (mshv_notify_acked_gsi(partition, eoi_msg->interrupt_vector)) {
+			handled = true;
+			goto unlock_out;
+		}
+	}
+
+	/*
+	 * We should get an opaque intercept message here for all intercept
+	 * messages, since we're using the mapped VP intercept message page.
+	 *
+	 * The intercept message will have been placed in intercept message
+	 * page at this point.
+	 *
+	 * Make sure the message type matches our expectation.
+	 */
+	if (msg->header.message_type != HVMSG_OPAQUE_INTERCEPT) {
+		pr_debug("wrong message type %d", msg->header.message_type);
+		goto unlock_out;
+	}
+
+	/*
+	 * Since we directly index the vp, and it has to exist for us to be here
+	 * (because the vp is only deleted when the partition is), no additional
+	 * locking is needed here
+	 */
+	vp_index =
+	       ((struct hv_opaque_intercept_message *)msg->u.payload)->vp_index;
+	/* This shouldn't happen, but just in case. */
+	if (unlikely(vp_index >= MSHV_MAX_VPS)) {
+		pr_debug("VP index %u out of bounds\n", vp_index);
+		goto unlock_out;
+	}
+	vp = partition->pt_vp_array[vp_index];
+	if (unlikely(!vp)) {
+		pr_debug("failed to find VP %u\n", vp_index);
+		goto unlock_out;
+	}
+
+	kick_vp(vp);
+
+	handled = true;
+
+unlock_out:
+	rcu_read_unlock();
+
+	return handled;
+}
+
+void mshv_isr(void)
+{
+	struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
+	struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
+	struct hv_message *msg;
+	bool handled;
+
+	if (unlikely(!(*msg_page))) {
+		pr_debug("Missing synic page!\n");
+		return;
+	}
+
+	msg = &((*msg_page)->sint_message[HV_SYNIC_INTERCEPTION_SINT_INDEX]);
+
+	/*
+	 * If the type isn't set, there isn't really a message;
+	 * it may be some other hyperv interrupt
+	 */
+	if (msg->header.message_type == HVMSG_NONE)
+		return;
+
+	handled = mshv_doorbell_isr(msg);
+
+	if (!handled)
+		handled = mshv_scheduler_isr(msg);
+
+	if (!handled)
+		handled = mshv_async_call_completion_isr(msg);
+
+	if (!handled)
+		handled = mshv_intercept_isr(msg);
+
+	if (handled) {
+		/*
+		 * Acknowledge message with hypervisor if another message is
+		 * pending.
+		 */
+		msg->header.message_type = HVMSG_NONE;
+		/*
+		 * Ensure the write is complete so the hypervisor will deliver
+		 * the next message if available.
+		 */
+		mb();
+		if (msg->header.message_flags.msg_pending)
+			hv_set_non_nested_msr(HV_MSR_EOM, 0);
+	} else {
+		pr_warn_once("%s: unknown message type 0x%x\n", __func__,
+			     msg->header.message_type);
+	}
+}
+
+static int mshv_synic_cpu_init(unsigned int cpu)
+{
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+	union hv_synic_sirbp sirbp;
+	union hv_synic_sint sint;
+	struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
+	struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
+	struct hv_synic_event_flags_page **event_flags_page =
+			&spages->synic_event_flags_page;
+	struct hv_synic_event_ring_page **event_ring_page =
+			&spages->synic_event_ring_page;
+	/*
+	 * VMBus owns SIMP/SIEFP/SCONTROL when it is active.
+	 * See hv_hyp_synic_enable_regs() for that initialization.
+	 */
+	bool vmbus_active = hv_vmbus_exists();
+
+	/*
+	 * Map the SYNIC message page. When VMBus is not active the
+	 * hypervisor pre-provisions the SIMP GPA but may not set
+	 * simp_enabled — enable it here.
+	 */
+	simp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIMP);
+	if (!vmbus_active) {
+		simp.simp_enabled = true;
+		hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64);
+	}
+	*msg_page = memremap(simp.base_simp_gpa << HV_HYP_PAGE_SHIFT,
+			     HV_HYP_PAGE_SIZE,
+			     MEMREMAP_WB);
+
+	if (!(*msg_page))
+		goto cleanup_simp;
+
+	/*
+	 * Map the event flags page. Same as SIMP: enable when
+	 * VMBus is not active, already enabled by VMBus otherwise.
+	 */
+	siefp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIEFP);
+	if (!vmbus_active) {
+		siefp.siefp_enabled = true;
+		hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64);
+	}
+	*event_flags_page = memremap(siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT,
+				     HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+
+	if (!(*event_flags_page))
+		goto cleanup_siefp;
+
+	/* Setup the Synic's event ring page */
+	sirbp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIRBP);
+
+	if (hv_root_partition()) {
+		*event_ring_page = memremap(sirbp.base_sirbp_gpa << HV_HYP_PAGE_SHIFT,
+					    HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+
+		if (!(*event_ring_page))
+			goto cleanup_siefp;
+	} else {
+		/*
+		 * On L1VH the hypervisor does not provide a SIRBP page.
+		 * Allocate one and program its GPA into the MSR.
+		 */
+		*event_ring_page = (struct hv_synic_event_ring_page *)
+			get_zeroed_page(GFP_KERNEL);
+
+		if (!(*event_ring_page))
+			goto cleanup_siefp;
+
+		sirbp.base_sirbp_gpa = virt_to_phys(*event_ring_page)
+				>> HV_HYP_PAGE_SHIFT;
+	}
+
+	sirbp.sirbp_enabled = true;
+	hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64);
+
+	if (mshv_sint_irq != -1)
+		enable_percpu_irq(mshv_sint_irq, 0);
+
+	/* Enable intercepts */
+	sint.as_uint64 = 0;
+	sint.vector = mshv_sint_vector;
+	sint.masked = false;
+	sint.auto_eoi = hv_recommend_using_aeoi();
+	hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_INTERCEPTION_SINT_INDEX,
+			      sint.as_uint64);
+
+	/* Doorbell SINT */
+	sint.as_uint64 = 0;
+	sint.vector = mshv_sint_vector;
+	sint.masked = false;
+	sint.as_intercept = 1;
+	sint.auto_eoi = hv_recommend_using_aeoi();
+	hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_DOORBELL_SINT_INDEX,
+			      sint.as_uint64);
+
+	/* When VMBus is active it already enabled SCONTROL. */
+	if (!vmbus_active) {
+		union hv_synic_scontrol sctrl;
+
+		sctrl.as_uint64 = hv_get_non_nested_msr(HV_MSR_SCONTROL);
+		sctrl.enable = 1;
+		hv_set_non_nested_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
+	}
+
+	return 0;
+
+cleanup_siefp:
+	if (*event_flags_page)
+		memunmap(*event_flags_page);
+	if (!vmbus_active) {
+		siefp.siefp_enabled = false;
+		hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64);
+	}
+cleanup_simp:
+	if (*msg_page)
+		memunmap(*msg_page);
+	if (!vmbus_active) {
+		simp.simp_enabled = false;
+		hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64);
+	}
+
+	return -EFAULT;
+}
+
+static int mshv_synic_cpu_exit(unsigned int cpu)
+{
+	union hv_synic_sint sint;
+	union hv_synic_sirbp sirbp;
+	struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
+	struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
+	struct hv_synic_event_flags_page **event_flags_page =
+		&spages->synic_event_flags_page;
+	struct hv_synic_event_ring_page **event_ring_page =
+		&spages->synic_event_ring_page;
+	/* VMBus owns SIMP/SIEFP/SCONTROL when it is active */
+	bool vmbus_active = hv_vmbus_exists();
+
+	/* Disable the interrupt */
+	sint.as_uint64 = hv_get_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_INTERCEPTION_SINT_INDEX);
+	sint.masked = true;
+	hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_INTERCEPTION_SINT_INDEX,
+			      sint.as_uint64);
+
+	/* Disable Doorbell SINT */
+	sint.as_uint64 = hv_get_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_DOORBELL_SINT_INDEX);
+	sint.masked = true;
+	hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_DOORBELL_SINT_INDEX,
+			      sint.as_uint64);
+
+	if (mshv_sint_irq != -1)
+		disable_percpu_irq(mshv_sint_irq);
+
+	/* Disable SYNIC event ring page owned by MSHV */
+	sirbp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIRBP);
+	sirbp.sirbp_enabled = false;
+
+	if (hv_root_partition()) {
+		hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64);
+		memunmap(*event_ring_page);
+	} else {
+		sirbp.base_sirbp_gpa = 0;
+		hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64);
+		free_page((unsigned long)*event_ring_page);
+	}
+
+	/*
+	 * Release our mappings of the message and event flags pages.
+	 * When VMBus is not active, we enabled SIMP/SIEFP — disable
+	 * them. Otherwise VMBus owns the MSRs — leave them.
+	 */
+	memunmap(*event_flags_page);
+	if (!vmbus_active) {
+		union hv_synic_simp simp;
+		union hv_synic_siefp siefp;
+
+		siefp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIEFP);
+		siefp.siefp_enabled = false;
+		hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64);
+
+		simp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIMP);
+		simp.simp_enabled = false;
+		hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64);
+	}
+	memunmap(*msg_page);
+
+	/* When VMBus is active it owns SCONTROL — leave it. */
+	if (!vmbus_active) {
+		union hv_synic_scontrol sctrl;
+
+		sctrl.as_uint64 = hv_get_non_nested_msr(HV_MSR_SCONTROL);
+		sctrl.enable = 0;
+		hv_set_non_nested_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
+	}
+
+	return 0;
+}
+
+int
+mshv_register_doorbell(u64 partition_id, doorbell_cb_t doorbell_cb, void *data,
+		       u64 gpa, u64 val, u64 flags)
+{
+	struct hv_connection_info connection_info = { 0 };
+	union hv_connection_id connection_id = { 0 };
+	struct port_table_info *port_table_info;
+	struct hv_port_info port_info = { 0 };
+	union hv_port_id port_id = { 0 };
+	int ret;
+
+	port_table_info = kmalloc_obj(*port_table_info);
+	if (!port_table_info)
+		return -ENOMEM;
+
+	port_table_info->hv_port_type = HV_PORT_TYPE_DOORBELL;
+	port_table_info->hv_port_doorbell.doorbell_cb = doorbell_cb;
+	port_table_info->hv_port_doorbell.data = data;
+	ret = mshv_portid_alloc(port_table_info);
+	if (ret < 0) {
+		kfree(port_table_info);
+		return ret;
+	}
+
+	port_id.u.id = ret;
+	port_info.port_type = HV_PORT_TYPE_DOORBELL;
+	port_info.doorbell_port_info.target_sint = HV_SYNIC_DOORBELL_SINT_INDEX;
+	port_info.doorbell_port_info.target_vp = HV_ANY_VP;
+	ret = hv_call_create_port(hv_current_partition_id, port_id, partition_id,
+				  &port_info,
+				  0, 0, NUMA_NO_NODE);
+
+	if (ret < 0) {
+		mshv_portid_free(port_id.u.id);
+		return ret;
+	}
+
+	connection_id.u.id = port_id.u.id;
+	connection_info.port_type = HV_PORT_TYPE_DOORBELL;
+	connection_info.doorbell_connection_info.gpa = gpa;
+	connection_info.doorbell_connection_info.trigger_value = val;
+	connection_info.doorbell_connection_info.flags = flags;
+
+	ret = hv_call_connect_port(hv_current_partition_id, port_id, partition_id,
+				   connection_id, &connection_info, 0, NUMA_NO_NODE);
+	if (ret < 0) {
+		hv_call_delete_port(hv_current_partition_id, port_id);
+		mshv_portid_free(port_id.u.id);
+		return ret;
+	}
+
+	// lets use the port_id as the doorbell_id
+	return port_id.u.id;
+}
+
+void
+mshv_unregister_doorbell(u64 partition_id, int doorbell_portid)
+{
+	union hv_port_id port_id = { 0 };
+	union hv_connection_id connection_id = { 0 };
+
+	connection_id.u.id = doorbell_portid;
+	hv_call_disconnect_port(partition_id, connection_id);
+
+	port_id.u.id = doorbell_portid;
+	hv_call_delete_port(hv_current_partition_id, port_id);
+
+	mshv_portid_free(doorbell_portid);
+}
+
+static int mshv_synic_reboot_notify(struct notifier_block *nb,
+			      unsigned long code, void *unused)
+{
+	mshv_debugfs_exit();
+	cpuhp_remove_state(synic_cpuhp_online);
+	return 0;
+}
+
+static struct notifier_block mshv_synic_reboot_nb = {
+	.notifier_call = mshv_synic_reboot_notify,
+};
+
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+static DEFINE_PER_CPU(long, mshv_evt);
+
+static irqreturn_t mshv_percpu_isr(int irq, void *dev_id)
+{
+	mshv_isr();
+	return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_ACPI
+static int __init mshv_acpi_setup_sint_irq(void)
+{
+	return acpi_register_gsi(NULL, mshv_sint_vector, ACPI_EDGE_SENSITIVE,
+					ACPI_ACTIVE_HIGH);
+}
+
+static void mshv_acpi_cleanup_sint_irq(void)
+{
+	acpi_unregister_gsi(mshv_sint_vector);
+}
+#else
+static int __init mshv_acpi_setup_sint_irq(void)
+{
+	return -ENODEV;
+}
+
+static void mshv_acpi_cleanup_sint_irq(void)
+{
+}
+#endif
+
+static int __init mshv_sint_vector_setup(void)
+{
+	int ret;
+	struct hv_register_assoc reg = {
+		.name = HV_ARM64_REGISTER_SINT_RESERVED_INTERRUPT_ID,
+	};
+	union hv_input_vtl input_vtl = { 0 };
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	ret = hv_call_get_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+				1, input_vtl, &reg);
+	if (ret || !reg.value.reg64)
+		return -ENODEV;
+
+	mshv_sint_vector = reg.value.reg64;
+	ret = mshv_acpi_setup_sint_irq();
+	if (ret < 0) {
+		pr_err("Failed to setup IRQ for MSHV SINT vector %d: %d\n",
+			mshv_sint_vector, ret);
+		goto out_fail;
+	}
+
+	mshv_sint_irq = ret;
+
+	ret = request_percpu_irq(mshv_sint_irq, mshv_percpu_isr, "MSHV",
+		&mshv_evt);
+	if (ret)
+		goto out_unregister;
+
+	return 0;
+
+out_unregister:
+	mshv_acpi_cleanup_sint_irq();
+out_fail:
+	return ret;
+}
+
+static void mshv_sint_vector_cleanup(void)
+{
+	free_percpu_irq(mshv_sint_irq, &mshv_evt);
+	mshv_acpi_cleanup_sint_irq();
+}
+#else /* !HYPERVISOR_CALLBACK_VECTOR */
+static int __init mshv_sint_vector_setup(void)
+{
+	mshv_sint_vector = HYPERVISOR_CALLBACK_VECTOR;
+	return 0;
+}
+
+static void mshv_sint_vector_cleanup(void)
+{
+}
+#endif /* HYPERVISOR_CALLBACK_VECTOR */
+
+int __init mshv_synic_init(struct device *dev)
+{
+	int ret = 0;
+
+	ret = mshv_sint_vector_setup();
+	if (ret)
+		return ret;
+
+	synic_pages = alloc_percpu(struct hv_synic_pages);
+	if (!synic_pages) {
+		dev_err(dev, "Failed to allocate percpu synic page\n");
+		ret = -ENOMEM;
+		goto sint_vector_cleanup;
+	}
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_synic",
+				mshv_synic_cpu_init,
+				mshv_synic_cpu_exit);
+	if (ret < 0) {
+		dev_err(dev, "Failed to setup cpu hotplug state: %i\n", ret);
+		goto free_synic_pages;
+	}
+
+	synic_cpuhp_online = ret;
+
+	ret = register_reboot_notifier(&mshv_synic_reboot_nb);
+	if (ret)
+		goto remove_cpuhp_state;
+
+	return 0;
+
+remove_cpuhp_state:
+	cpuhp_remove_state(synic_cpuhp_online);
+free_synic_pages:
+	free_percpu(synic_pages);
+sint_vector_cleanup:
+	mshv_sint_vector_cleanup();
+	return ret;
+}
+
+void mshv_synic_exit(void)
+{
+	unregister_reboot_notifier(&mshv_synic_reboot_nb);
+	cpuhp_remove_state(synic_cpuhp_online);
+	free_percpu(synic_pages);
+	mshv_sint_vector_cleanup();
+}
diff --git a/drivers/hv/mshv_trace.c b/drivers/hv/mshv_trace.c
new file mode 100644
index 000000000..0936b2f95
--- /dev/null
+++ b/drivers/hv/mshv_trace.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026, Microsoft Corporation.
+ *
+ * Tracepoint definitions for mshv driver.
+ */
+
+#define CREATE_TRACE_POINTS
+#include "mshv_trace.h"
diff --git a/drivers/hv/mshv_trace.h b/drivers/hv/mshv_trace.h
new file mode 100644
index 000000000..e7280c47e
--- /dev/null
+++ b/drivers/hv/mshv_trace.h
@@ -0,0 +1,544 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2026, Microsoft Corporation.
+ *
+ * Tracepoint declarations for mshv driver.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mshv
+
+#if !defined(__MSHV_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _MSHV_TRACE_H_
+
+#include <linux/tracepoint.h>
+#include <hyperv/hvhdk.h>
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ../../drivers/hv
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE mshv_trace
+
+TRACE_EVENT(mshv_create_partition,
+	    TP_PROTO(u64 partition_id, int vm_fd),
+	    TP_ARGS(partition_id, vm_fd),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(int, vm_fd)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vm_fd = vm_fd;
+	    ),
+	    TP_printk("partition_id=%llu vm_fd=%d",
+		    __entry->partition_id,
+		    __entry->vm_fd
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_create_partition,
+	    TP_PROTO(u64 flags, s64 partition_id),
+	    TP_ARGS(flags, partition_id),
+	    TP_STRUCT__entry(
+		    __field(u64, flags)
+		    __field(s64, partition_id)
+	    ),
+	    TP_fast_assign(
+		    __entry->flags = flags;
+		    __entry->partition_id = partition_id;
+	    ),
+	    TP_printk("flags=%#llx partition_id=%lld",
+		    __entry->flags,
+		    __entry->partition_id
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_initialize_partition,
+	    TP_PROTO(u64 partition_id, u64 status),
+	    TP_ARGS(partition_id, status),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, status)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->status = status;
+	    ),
+	    TP_printk("partition_id=%llu status=%#llx",
+		    __entry->partition_id,
+		    __entry->status
+	    )
+);
+
+TRACE_EVENT(mshv_partition_release,
+	    TP_PROTO(u64 partition_id),
+	    TP_ARGS(partition_id),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+	    ),
+	    TP_printk("partition_id=%llu",
+		    __entry->partition_id
+	    )
+);
+
+TRACE_EVENT(mshv_destroy_partition,
+	    TP_PROTO(u64 partition_id),
+	    TP_ARGS(partition_id),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+	    ),
+	    TP_printk("partition_id=%llu",
+		    __entry->partition_id
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_finalize_partition,
+	    TP_PROTO(u64 partition_id, u64 status),
+	    TP_ARGS(partition_id, status),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, status)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->status = status;
+	    ),
+	    TP_printk("partition_id=%llu status=%#llx ",
+		    __entry->partition_id,
+		    __entry->status
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_withdraw_memory,
+	    TP_PROTO(u64 partition_id, u64 withdrawn, u64 status),
+	    TP_ARGS(partition_id, withdrawn, status),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, withdrawn)
+		    __field(u64, status)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->withdrawn = withdrawn;
+		    __entry->status = status;
+	    ),
+	    TP_printk("partition_id=%llu withdrawn=%llu status=%#llx",
+		    __entry->partition_id,
+		    __entry->withdrawn,
+		    __entry->status
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_delete_partition,
+	    TP_PROTO(u64 partition_id, u64 status),
+	    TP_ARGS(partition_id, status),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, status)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->status = status;
+	    ),
+	    TP_printk("partition_id=%llu status=%#llx",
+		    __entry->partition_id,
+		    __entry->status
+	    )
+);
+
+TRACE_EVENT(mshv_create_vp,
+	    TP_PROTO(u64 partition_id, u32 vp_index, long vp_fd),
+	    TP_ARGS(partition_id, vp_index, vp_fd),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(long, vp_fd)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->vp_fd = vp_fd;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u vp_fd=%ld",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->vp_fd
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_map_vp_state_page,
+	    TP_PROTO(u64 partition_id, u32 vp_index, u32 page_type, u64 status),
+	    TP_ARGS(partition_id, vp_index, page_type, status),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(u32, page_type)
+		    __field(u64, status)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->page_type = page_type;
+		    __entry->status = status;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u page_type=%u status=%#llx",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->page_type,
+		    __entry->status
+	    )
+);
+
+TRACE_EVENT(mshv_drain_vp_signals,
+	    TP_PROTO(u64 partition_id, u32 vp_index),
+	    TP_ARGS(partition_id, vp_index),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u",
+		    __entry->partition_id,
+		    __entry->vp_index
+	    )
+);
+
+TRACE_EVENT(mshv_disable_vp_dispatch,
+	    TP_PROTO(u64 partition_id, u32 vp_index, int ret),
+	    TP_ARGS(partition_id, vp_index, ret),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(int, ret)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->ret = ret;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u ret=%d",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->ret
+	    )
+);
+
+TRACE_EVENT(mshv_vp_release,
+	    TP_PROTO(u64 partition_id, u32 vp_index),
+	    TP_ARGS(partition_id, vp_index),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u",
+		    __entry->partition_id,
+		    __entry->vp_index
+	    )
+);
+
+TRACE_EVENT(mshv_run_vp_entry,
+	    TP_PROTO(u64 partition_id, u32 vp_index),
+	    TP_ARGS(partition_id, vp_index),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u",
+		    __entry->partition_id,
+		    __entry->vp_index
+	    )
+);
+
+TRACE_EVENT(mshv_run_vp_exit,
+	    TP_PROTO(u64 partition_id, u32 vp_index, u64 hv_message_type, long ret),
+	    TP_ARGS(partition_id, vp_index, hv_message_type, ret),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(u64, hv_message_type)
+		    __field(long, ret)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->hv_message_type = hv_message_type;
+		    __entry->ret = ret;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u hv_message_type=%#llx ret=%ld",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->hv_message_type,
+		    __entry->ret
+	    )
+);
+
+TRACE_EVENT(mshv_vp_clear_explicit_suspend,
+	    TP_PROTO(u64 partition_id, u32 vp_index, int ret),
+	    TP_ARGS(partition_id, vp_index, ret),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(int, ret)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->ret = ret;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u ret=%d",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->ret
+	    )
+);
+
+TRACE_EVENT(mshv_xfer_to_guest_mode_work,
+	    TP_PROTO(u64 partition_id, u32 vp_index, unsigned long thread_info_flag, long ret),
+	    TP_ARGS(partition_id, vp_index, thread_info_flag, ret),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(unsigned long, thread_info_flag)
+		    __field(long, ret)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->thread_info_flag = thread_info_flag;
+		    __entry->ret = ret;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u thread_info_flag=%#lx ret=%ld",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->thread_info_flag,
+		    __entry->ret
+	    )
+);
+
+TRACE_EVENT(mshv_hvcall_dispatch_vp,
+	    TP_PROTO(u64 partition_id, u32 vp_index, u32 flags,
+		     u32 dispatch_state, u32 dispatch_event, u64 irq_vectors, u64 status),
+	    TP_ARGS(partition_id, vp_index, flags, dispatch_state, dispatch_event, irq_vectors,
+		    status),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(u32, flags)
+		    __field(u32, dispatch_state)
+		    __field(u32, dispatch_event)
+		    __field(u64, irq_vectors)
+		    __field(u64, status)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->flags = flags;
+		    __entry->dispatch_state = dispatch_state;
+		    __entry->dispatch_event = dispatch_event;
+		    __entry->irq_vectors = irq_vectors;
+		    __entry->status = status;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u flags=%#x dispatch_state=%#x dispatch_event=%#x irq_vectors=%#016llx status=%#llx",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->flags,
+		    __entry->dispatch_state,
+		    __entry->dispatch_event,
+		    __entry->irq_vectors,
+		    __entry->status
+	     )
+);
+
+TRACE_EVENT(mshv_update_routing_table,
+	    TP_PROTO(u64 partition_id, void *old, void *new, u32 numents),
+	    TP_ARGS(partition_id, old, new, numents),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(struct mshv_girq_routing_table *, old)
+		    __field(struct mshv_girq_routing_table *, new)
+		    __field(u32, numents)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->old = old;
+		    __entry->new = new;
+		    __entry->numents = numents;
+	    ),
+	    TP_printk("partition_id=%llu old=%p new=%p numents=%u",
+		    __entry->partition_id,
+		    __entry->old,
+		    __entry->new,
+		    __entry->numents
+	    )
+);
+
+TRACE_EVENT(mshv_map_user_memory,
+	    TP_PROTO(u64 partition_id, u64 start_uaddr, u64 start_gfn, u64 nr_pages, u32 map_flags,
+		     long ret),
+	    TP_ARGS(partition_id, start_uaddr, start_gfn, nr_pages, map_flags, ret),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, start_uaddr)
+		    __field(u64, start_gfn)
+		    __field(u64, nr_pages)
+		    __field(u32, map_flags)
+		    __field(long, ret)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->start_uaddr = start_uaddr;
+		    __entry->start_gfn = start_gfn;
+		    __entry->nr_pages = nr_pages;
+		    __entry->map_flags = map_flags;
+		    __entry->ret = ret;
+	    ),
+	    TP_printk("partition_id=%llu start_uaddr=%#llx start_gfn=%#llx nr_pages=%llu map_flags=%#x ret=%ld",
+		    __entry->partition_id,
+		    __entry->start_uaddr,
+		    __entry->start_gfn,
+		    __entry->nr_pages,
+		    __entry->map_flags,
+		    __entry->ret
+	     )
+);
+
+TRACE_EVENT(mshv_assign_ioeventfd,
+	    TP_PROTO(u64 partition_id, u64 addr, u64 length, u64 datamatch, bool wildcard,
+		     void *eventfd, int ret),
+	    TP_ARGS(partition_id, addr, length, datamatch, wildcard, eventfd, ret),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, addr)
+		    __field(u64, length)
+		    __field(u64, datamatch)
+		    __field(bool, wildcard)
+		    __field(struct eventfd_ctx *, eventfd)
+		    __field(int, ret)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->addr = addr;
+		    __entry->length = length;
+		    __entry->datamatch = datamatch;
+		    __entry->wildcard = wildcard;
+		    __entry->eventfd = eventfd;
+		    __entry->ret = ret;
+	    ),
+	    TP_printk("partition_id=%llu addr=%#016llx length=%#llx datamatch=%#llx wildcard=%d eventfd=%p ret=%d",
+		    __entry->partition_id,
+		    __entry->addr,
+		    __entry->length,
+		    __entry->datamatch,
+		    __entry->wildcard,
+		    __entry->eventfd,
+		    __entry->ret
+	     )
+);
+
+TRACE_EVENT(mshv_deassign_ioeventfd,
+	    TP_PROTO(u64 partition_id, u64 addr, u64 length, u64 datamatch, bool wildcard,
+		     void *eventfd),
+	    TP_ARGS(partition_id, addr, length, datamatch, wildcard, eventfd),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u64, addr)
+		    __field(u64, length)
+		    __field(u64, datamatch)
+		    __field(bool, wildcard)
+		    __field(struct eventfd_ctx *, eventfd)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->addr = addr;
+		    __entry->length = length;
+		    __entry->datamatch = datamatch;
+		    __entry->wildcard = wildcard;
+		    __entry->eventfd = eventfd;
+	    ),
+	    TP_printk("partition_id=%llu addr=%#016llx length=%#llx datamatch=%#llx wildcard=%d eventfd=%p",
+		    __entry->partition_id,
+		    __entry->addr,
+		    __entry->length,
+		    __entry->datamatch,
+		    __entry->wildcard,
+		    __entry->eventfd
+	     )
+);
+
+TRACE_EVENT(mshv_vp_wait_for_hv_kick,
+	    TP_PROTO(u64 partition_id, u32 vp_index, bool kicked_by_hv, bool blocked,
+		     bool irq_pending),
+	    TP_ARGS(partition_id, vp_index, kicked_by_hv, blocked, irq_pending),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(bool, kicked_by_hv)
+		    __field(bool, blocked)
+		    __field(bool, irq_pending)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->kicked_by_hv = kicked_by_hv;
+		    __entry->blocked = blocked;
+		    __entry->irq_pending = irq_pending;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u kicked_by_hv=%d blocked=%d irq_pending=%d",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->kicked_by_hv,
+		    __entry->blocked,
+		    __entry->irq_pending
+	    )
+);
+
+TRACE_EVENT(mshv_handle_gpa_intercept,
+	    TP_PROTO(u64 partition_id, u32 vp_index, u64 gfn, u8 access_type, bool handled),
+	    TP_ARGS(partition_id, vp_index, gfn, access_type, handled),
+	    TP_STRUCT__entry(
+		    __field(u64, partition_id)
+		    __field(u32, vp_index)
+		    __field(u64, gfn)
+		    __field(u8, access_type)
+		    __field(bool, handled)
+	    ),
+	    TP_fast_assign(
+		    __entry->partition_id = partition_id;
+		    __entry->vp_index = vp_index;
+		    __entry->gfn = gfn;
+		    __entry->access_type = access_type == HV_INTERCEPT_ACCESS_READ ? 'R' :
+					   (access_type == HV_INTERCEPT_ACCESS_WRITE ? 'W' :
+					    (access_type == HV_INTERCEPT_ACCESS_EXECUTE ? 'X' : '?'));
+		    __entry->handled = handled;
+	    ),
+	    TP_printk("partition_id=%llu vp_index=%u gfn=0x%llx access_type=%c handled=%d",
+		    __entry->partition_id,
+		    __entry->vp_index,
+		    __entry->gfn,
+		    __entry->access_type,
+		    __entry->handled
+	    )
+);
+
+#endif /* _MSHV_TRACE_H_ */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/drivers/hv/mshv_vtl.h b/drivers/hv/mshv_vtl.h
new file mode 100644
index 000000000..a6eea52f7
--- /dev/null
+++ b/drivers/hv/mshv_vtl.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _MSHV_VTL_H
+#define _MSHV_VTL_H
+
+#include <linux/mshv.h>
+#include <linux/types.h>
+
+struct mshv_vtl_run {
+	u32 cancel;
+	u32 vtl_ret_action_size;
+	u32 pad[2];
+	char exit_message[MSHV_MAX_RUN_MSG_SIZE];
+	union {
+		struct mshv_vtl_cpu_context cpu_context;
+
+		/*
+		 * Reserving room for the cpu context to grow and to maintain compatibility
+		 * with user mode.
+		 */
+		char reserved[1024];
+	};
+	char vtl_ret_actions[MSHV_MAX_RUN_MSG_SIZE];
+};
+
+#endif /* _MSHV_VTL_H */
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
new file mode 100644
index 000000000..6e3c11c68
--- /dev/null
+++ b/drivers/hv/mshv_vtl_main.c
@@ -0,0 +1,1410 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023, Microsoft Corporation.
+ *
+ * Author:
+ *   Roman Kisel <romank@linux.microsoft.com>
+ *   Saurabh Sengar <ssengar@linux.microsoft.com>
+ *   Naman Jain <namjain@linux.microsoft.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/anon_inodes.h>
+#include <linux/cpuhotplug.h>
+#include <linux/count_zeros.h>
+#include <linux/entry-virt.h>
+#include <linux/eventfd.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/vmalloc.h>
+#include <asm/debugreg.h>
+#include <asm/mshyperv.h>
+#include <trace/events/ipi.h>
+#include <uapi/asm/mtrr.h>
+#include <uapi/linux/mshv.h>
+#include <hyperv/hvhdk.h>
+
+#include "../../kernel/fpu/legacy.h"
+#include "mshv.h"
+#include "mshv_vtl.h"
+#include "hyperv_vmbus.h"
+
+MODULE_AUTHOR("Microsoft");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Microsoft Hyper-V VTL Driver");
+
+#define MSHV_ENTRY_REASON_LOWER_VTL_CALL     0x1
+#define MSHV_ENTRY_REASON_INTERRUPT          0x2
+#define MSHV_ENTRY_REASON_INTERCEPT          0x3
+
+#define MSHV_REAL_OFF_SHIFT	16
+#define MSHV_PG_OFF_CPU_MASK	(BIT_ULL(MSHV_REAL_OFF_SHIFT) - 1)
+#define MSHV_RUN_PAGE_OFFSET	0
+#define MSHV_REG_PAGE_OFFSET	1
+#define VTL2_VMBUS_SINT_INDEX	7
+
+static struct device *mem_dev;
+
+static struct tasklet_struct msg_dpc;
+static wait_queue_head_t fd_wait_queue;
+static bool has_message;
+static struct eventfd_ctx *flag_eventfds[HV_EVENT_FLAGS_COUNT];
+static DEFINE_MUTEX(flag_lock);
+static bool __read_mostly mshv_has_reg_page;
+
+/* hvcall code is of type u16, allocate a bitmap of size (1 << 16) to accommodate it */
+#define MAX_BITMAP_SIZE ((U16_MAX + 1) / 8)
+
+struct mshv_vtl_hvcall_fd {
+	u8 allow_bitmap[MAX_BITMAP_SIZE];
+	bool allow_map_initialized;
+	/*
+	 * Used to protect hvcall setup in IOCTLs
+	 */
+	struct mutex init_mutex;
+	struct miscdevice *dev;
+};
+
+struct mshv_vtl_poll_file {
+	struct file *file;
+	wait_queue_entry_t wait;
+	wait_queue_head_t *wqh;
+	poll_table pt;
+	int cpu;
+};
+
+struct mshv_vtl {
+	struct device *module_dev;
+	u64 id;
+};
+
+struct mshv_vtl_per_cpu {
+	struct mshv_vtl_run *run;
+	struct page *reg_page;
+};
+
+/* SYNIC_OVERLAY_PAGE_MSR - internal, identical to hv_synic_simp */
+union hv_synic_overlay_page_msr {
+	u64 as_uint64;
+	struct {
+		u64 enabled: 1;
+		u64 reserved: 11;
+		u64 pfn: 52;
+	} __packed;
+};
+
+static struct mutex mshv_vtl_poll_file_lock;
+static union hv_register_vsm_page_offsets mshv_vsm_page_offsets;
+static union hv_register_vsm_capabilities mshv_vsm_capabilities;
+
+static DEFINE_PER_CPU(struct mshv_vtl_poll_file, mshv_vtl_poll_file);
+static DEFINE_PER_CPU(unsigned long long, num_vtl0_transitions);
+static DEFINE_PER_CPU(struct mshv_vtl_per_cpu, mshv_vtl_per_cpu);
+
+static const union hv_input_vtl input_vtl_zero;
+static const union hv_input_vtl input_vtl_normal = {
+	.use_target_vtl = 1,
+};
+
+static const struct file_operations mshv_vtl_fops;
+
+static long
+mshv_ioctl_create_vtl(void __user *user_arg, struct device *module_dev)
+{
+	struct mshv_vtl *vtl;
+	struct file *file;
+	int fd;
+
+	vtl = kzalloc_obj(*vtl);
+	if (!vtl)
+		return -ENOMEM;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0) {
+		kfree(vtl);
+		return fd;
+	}
+	file = anon_inode_getfile("mshv_vtl", &mshv_vtl_fops,
+				  vtl, O_RDWR);
+	if (IS_ERR(file)) {
+		put_unused_fd(fd);
+		kfree(vtl);
+		return PTR_ERR(file);
+	}
+	vtl->module_dev = module_dev;
+	fd_install(fd, file);
+
+	return fd;
+}
+
+static long
+mshv_ioctl_check_extension(void __user *user_arg)
+{
+	u32 arg;
+
+	if (copy_from_user(&arg, user_arg, sizeof(arg)))
+		return -EFAULT;
+
+	switch (arg) {
+	case MSHV_CAP_CORE_API_STABLE:
+		return 0;
+	case MSHV_CAP_REGISTER_PAGE:
+		return mshv_has_reg_page;
+	case MSHV_CAP_VTL_RETURN_ACTION:
+		return mshv_vsm_capabilities.return_action_available;
+	case MSHV_CAP_DR6_SHARED:
+		return mshv_vsm_capabilities.dr6_shared;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static long
+mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	struct miscdevice *misc = filp->private_data;
+
+	switch (ioctl) {
+	case MSHV_CHECK_EXTENSION:
+		return mshv_ioctl_check_extension((void __user *)arg);
+	case MSHV_CREATE_VTL:
+		return mshv_ioctl_create_vtl((void __user *)arg, misc->this_device);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations mshv_dev_fops = {
+	.owner		= THIS_MODULE,
+	.unlocked_ioctl	= mshv_dev_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice mshv_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "mshv",
+	.fops = &mshv_dev_fops,
+	.mode = 0600,
+};
+
+static struct mshv_vtl_run *mshv_vtl_this_run(void)
+{
+	return *this_cpu_ptr(&mshv_vtl_per_cpu.run);
+}
+
+static struct mshv_vtl_run *mshv_vtl_cpu_run(int cpu)
+{
+	return *per_cpu_ptr(&mshv_vtl_per_cpu.run, cpu);
+}
+
+static struct page *mshv_vtl_cpu_reg_page(int cpu)
+{
+	return *per_cpu_ptr(&mshv_vtl_per_cpu.reg_page, cpu);
+}
+
+static void mshv_vtl_configure_reg_page(struct mshv_vtl_per_cpu *per_cpu)
+{
+	struct hv_register_assoc reg_assoc = {};
+	union hv_synic_overlay_page_msr overlay = {};
+	struct page *reg_page;
+
+	reg_page = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL);
+	if (!reg_page) {
+		WARN(1, "failed to allocate register page\n");
+		return;
+	}
+
+	overlay.enabled = 1;
+	overlay.pfn = page_to_hvpfn(reg_page);
+	reg_assoc.name = HV_X64_REGISTER_REG_PAGE;
+	reg_assoc.value.reg64 = overlay.as_uint64;
+
+	if (hv_call_set_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+				     1, input_vtl_zero, &reg_assoc)) {
+		WARN(1, "failed to setup register page\n");
+		__free_page(reg_page);
+		return;
+	}
+
+	per_cpu->reg_page = reg_page;
+	mshv_has_reg_page = true;
+}
+
+static void mshv_vtl_synic_enable_regs(unsigned int cpu)
+{
+	union hv_synic_sint sint;
+
+	sint.as_uint64 = 0;
+	sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+	sint.masked = false;
+	sint.auto_eoi = hv_recommend_using_aeoi();
+
+	/* Enable intercepts */
+	if (!mshv_vsm_capabilities.intercept_page_available)
+		hv_set_msr(HV_MSR_SINT0 + HV_SYNIC_INTERCEPTION_SINT_INDEX,
+			   sint.as_uint64);
+
+	/* VTL2 Host VSP SINT is (un)masked when the user mode requests that */
+}
+
+static int mshv_vtl_get_vsm_regs(void)
+{
+	struct hv_register_assoc registers[2];
+	int ret, count = 2;
+
+	registers[0].name = HV_REGISTER_VSM_CODE_PAGE_OFFSETS;
+	registers[1].name = HV_REGISTER_VSM_CAPABILITIES;
+
+	ret = hv_call_get_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+				       count, input_vtl_zero, registers);
+	if (ret)
+		return ret;
+
+	mshv_vsm_page_offsets.as_uint64 = registers[0].value.reg64;
+	mshv_vsm_capabilities.as_uint64 = registers[1].value.reg64;
+
+	return ret;
+}
+
+static int mshv_vtl_configure_vsm_partition(struct device *dev)
+{
+	union hv_register_vsm_partition_config config;
+	struct hv_register_assoc reg_assoc;
+
+	config.as_uint64 = 0;
+	config.default_vtl_protection_mask = HV_MAP_GPA_PERMISSIONS_MASK;
+	config.enable_vtl_protection = 1;
+	config.zero_memory_on_reset = 1;
+	config.intercept_vp_startup = 1;
+	config.intercept_cpuid_unimplemented = 1;
+
+	if (mshv_vsm_capabilities.intercept_page_available) {
+		dev_dbg(dev, "using intercept page\n");
+		config.intercept_page = 1;
+	}
+
+	reg_assoc.name = HV_REGISTER_VSM_PARTITION_CONFIG;
+	reg_assoc.value.reg64 = config.as_uint64;
+
+	return hv_call_set_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+				       1, input_vtl_zero, &reg_assoc);
+}
+
+static void mshv_vtl_vmbus_isr(void)
+{
+	struct hv_per_cpu_context *per_cpu;
+	struct hv_message *msg;
+	u32 message_type;
+	union hv_synic_event_flags *event_flags;
+	struct eventfd_ctx *eventfd;
+	u16 i;
+
+	per_cpu = this_cpu_ptr(hv_context.cpu_context);
+	if (smp_processor_id() == 0) {
+		msg = (struct hv_message *)per_cpu->hyp_synic_message_page + VTL2_VMBUS_SINT_INDEX;
+		message_type = READ_ONCE(msg->header.message_type);
+		if (message_type != HVMSG_NONE)
+			tasklet_schedule(&msg_dpc);
+	}
+
+	event_flags = (union hv_synic_event_flags *)per_cpu->hyp_synic_event_page +
+			VTL2_VMBUS_SINT_INDEX;
+	for_each_set_bit(i, event_flags->flags, HV_EVENT_FLAGS_COUNT) {
+		if (!sync_test_and_clear_bit(i, event_flags->flags))
+			continue;
+		rcu_read_lock();
+		eventfd = READ_ONCE(flag_eventfds[i]);
+		if (eventfd)
+			eventfd_signal(eventfd);
+		rcu_read_unlock();
+	}
+
+	vmbus_isr();
+}
+
+static int mshv_vtl_alloc_context(unsigned int cpu)
+{
+	struct mshv_vtl_per_cpu *per_cpu = this_cpu_ptr(&mshv_vtl_per_cpu);
+
+	per_cpu->run = (struct mshv_vtl_run *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	if (!per_cpu->run)
+		return -ENOMEM;
+
+	if (mshv_vsm_capabilities.intercept_page_available)
+		mshv_vtl_configure_reg_page(per_cpu);
+
+	mshv_vtl_synic_enable_regs(cpu);
+
+	return 0;
+}
+
+static int mshv_vtl_cpuhp_online;
+
+static int hv_vtl_setup_synic(void)
+{
+	int ret;
+
+	/* Use our isr to first filter out packets destined for userspace */
+	hv_setup_vmbus_handler(mshv_vtl_vmbus_isr);
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vtl:online",
+				mshv_vtl_alloc_context, NULL);
+	if (ret < 0) {
+		hv_setup_vmbus_handler(vmbus_isr);
+		return ret;
+	}
+
+	mshv_vtl_cpuhp_online = ret;
+
+	return 0;
+}
+
+static void hv_vtl_remove_synic(void)
+{
+	cpuhp_remove_state(mshv_vtl_cpuhp_online);
+	hv_setup_vmbus_handler(vmbus_isr);
+}
+
+static int vtl_get_vp_register(struct hv_register_assoc *reg)
+{
+	return hv_call_get_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+					1, input_vtl_normal, reg);
+}
+
+static int vtl_set_vp_register(struct hv_register_assoc *reg)
+{
+	return hv_call_set_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+					1, input_vtl_normal, reg);
+}
+
+static int mshv_vtl_ioctl_add_vtl0_mem(struct mshv_vtl *vtl, void __user *arg)
+{
+	struct mshv_vtl_ram_disposition vtl0_mem;
+	struct dev_pagemap *pgmap;
+	void *addr;
+
+	if (copy_from_user(&vtl0_mem, arg, sizeof(vtl0_mem)))
+		return -EFAULT;
+	if (vtl0_mem.last_pfn <= vtl0_mem.start_pfn) {
+		dev_err(vtl->module_dev, "range start pfn (%llx) > end pfn (%llx)\n",
+			vtl0_mem.start_pfn, vtl0_mem.last_pfn);
+		return -EFAULT;
+	}
+
+	pgmap = kzalloc_obj(*pgmap);
+	if (!pgmap)
+		return -ENOMEM;
+
+	/*
+	 * vtl0_mem.last_pfn is excluded in the pagemap range for VTL0 as per design.
+	 * last_pfn is not reserved or wasted, and reflects 'start_pfn + size' of pagemap range.
+	 */
+	pgmap->ranges[0].start = PFN_PHYS(vtl0_mem.start_pfn);
+	pgmap->ranges[0].end = PFN_PHYS(vtl0_mem.last_pfn) - 1;
+	pgmap->nr_range = 1;
+	pgmap->type = MEMORY_DEVICE_GENERIC;
+
+	/*
+	 * Determine the highest page order that can be used for the given memory range.
+	 * This works best when the range is aligned; i.e. both the start and the length.
+	 * Clamp to MAX_FOLIO_ORDER to avoid a WARN in memremap_pages() when the range
+	 * alignment exceeds the maximum supported folio order for this kernel config.
+	 */
+	pgmap->vmemmap_shift = min(count_trailing_zeros(vtl0_mem.start_pfn | vtl0_mem.last_pfn),
+				   MAX_FOLIO_ORDER);
+	dev_dbg(vtl->module_dev,
+		"Add VTL0 memory: start: 0x%llx, end_pfn: 0x%llx, page order: %lu\n",
+		vtl0_mem.start_pfn, vtl0_mem.last_pfn, pgmap->vmemmap_shift);
+
+	addr = devm_memremap_pages(mem_dev, pgmap);
+	if (IS_ERR(addr)) {
+		dev_err(vtl->module_dev, "devm_memremap_pages error: %ld\n", PTR_ERR(addr));
+		kfree(pgmap);
+		return PTR_ERR(addr);
+	}
+
+	/* Don't free pgmap, since it has to stick around until the memory
+	 * is unmapped, which will never happen as there is no scenario
+	 * where VTL0 can be released/shutdown without bringing down VTL2.
+	 */
+	return 0;
+}
+
+static void mshv_vtl_cancel(int cpu)
+{
+	int here = get_cpu();
+
+	if (here != cpu) {
+		if (!xchg_relaxed(&mshv_vtl_cpu_run(cpu)->cancel, 1))
+			smp_send_reschedule(cpu);
+	} else {
+		WRITE_ONCE(mshv_vtl_this_run()->cancel, 1);
+	}
+	put_cpu();
+}
+
+static int mshv_vtl_poll_file_wake(wait_queue_entry_t *wait, unsigned int mode, int sync, void *key)
+{
+	struct mshv_vtl_poll_file *poll_file = container_of(wait, struct mshv_vtl_poll_file, wait);
+
+	mshv_vtl_cancel(poll_file->cpu);
+
+	return 0;
+}
+
+static void mshv_vtl_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh, poll_table *pt)
+{
+	struct mshv_vtl_poll_file *poll_file = container_of(pt, struct mshv_vtl_poll_file, pt);
+
+	WARN_ON(poll_file->wqh);
+	poll_file->wqh = wqh;
+	add_wait_queue(wqh, &poll_file->wait);
+}
+
+static int mshv_vtl_ioctl_set_poll_file(struct mshv_vtl_set_poll_file __user *user_input)
+{
+	struct file *file, *old_file;
+	struct mshv_vtl_poll_file *poll_file;
+	struct mshv_vtl_set_poll_file input;
+
+	if (copy_from_user(&input, user_input, sizeof(input)))
+		return -EFAULT;
+
+	if (input.cpu >= num_possible_cpus() || !cpu_online(input.cpu))
+		return -EINVAL;
+	/*
+	 * CPU Hotplug is not supported in VTL2 in OpenHCL, where this kernel driver exists.
+	 * CPU is expected to remain online after above cpu_online() check.
+	 */
+
+	file = NULL;
+	file = fget(input.fd);
+	if (!file)
+		return -EBADFD;
+
+	poll_file = per_cpu_ptr(&mshv_vtl_poll_file, READ_ONCE(input.cpu));
+	if (!poll_file)
+		return -EINVAL;
+
+	mutex_lock(&mshv_vtl_poll_file_lock);
+
+	if (poll_file->wqh)
+		remove_wait_queue(poll_file->wqh, &poll_file->wait);
+	poll_file->wqh = NULL;
+
+	old_file = poll_file->file;
+	poll_file->file = file;
+	poll_file->cpu = input.cpu;
+
+	if (file) {
+		init_waitqueue_func_entry(&poll_file->wait, mshv_vtl_poll_file_wake);
+		init_poll_funcptr(&poll_file->pt, mshv_vtl_ptable_queue_proc);
+		vfs_poll(file, &poll_file->pt);
+	}
+
+	mutex_unlock(&mshv_vtl_poll_file_lock);
+
+	if (old_file)
+		fput(old_file);
+
+	return 0;
+}
+
+/* Static table mapping register names to their corresponding actions */
+static const struct {
+	enum hv_register_name reg_name;
+	int debug_reg_num;  /* -1 if not a debug register */
+	u32 msr_addr;       /* 0 if not an MSR */
+} reg_table[] = {
+	/* Debug registers */
+	{HV_X64_REGISTER_DR0, 0, 0},
+	{HV_X64_REGISTER_DR1, 1, 0},
+	{HV_X64_REGISTER_DR2, 2, 0},
+	{HV_X64_REGISTER_DR3, 3, 0},
+	{HV_X64_REGISTER_DR6, 6, 0},
+	/* MTRR MSRs */
+	{HV_X64_REGISTER_MSR_MTRR_CAP, -1, MSR_MTRRcap},
+	{HV_X64_REGISTER_MSR_MTRR_DEF_TYPE, -1, MSR_MTRRdefType},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE0, -1, MTRRphysBase_MSR(0)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE1, -1, MTRRphysBase_MSR(1)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE2, -1, MTRRphysBase_MSR(2)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE3, -1, MTRRphysBase_MSR(3)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE4, -1, MTRRphysBase_MSR(4)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE5, -1, MTRRphysBase_MSR(5)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE6, -1, MTRRphysBase_MSR(6)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE7, -1, MTRRphysBase_MSR(7)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE8, -1, MTRRphysBase_MSR(8)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASE9, -1, MTRRphysBase_MSR(9)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEA, -1, MTRRphysBase_MSR(0xa)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEB, -1, MTRRphysBase_MSR(0xb)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEC, -1, MTRRphysBase_MSR(0xc)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASED, -1, MTRRphysBase_MSR(0xd)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEE, -1, MTRRphysBase_MSR(0xe)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_BASEF, -1, MTRRphysBase_MSR(0xf)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK0, -1, MTRRphysMask_MSR(0)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK1, -1, MTRRphysMask_MSR(1)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK2, -1, MTRRphysMask_MSR(2)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK3, -1, MTRRphysMask_MSR(3)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK4, -1, MTRRphysMask_MSR(4)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK5, -1, MTRRphysMask_MSR(5)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK6, -1, MTRRphysMask_MSR(6)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK7, -1, MTRRphysMask_MSR(7)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK8, -1, MTRRphysMask_MSR(8)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASK9, -1, MTRRphysMask_MSR(9)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKA, -1, MTRRphysMask_MSR(0xa)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKB, -1, MTRRphysMask_MSR(0xb)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKC, -1, MTRRphysMask_MSR(0xc)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKD, -1, MTRRphysMask_MSR(0xd)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKE, -1, MTRRphysMask_MSR(0xe)},
+	{HV_X64_REGISTER_MSR_MTRR_PHYS_MASKF, -1, MTRRphysMask_MSR(0xf)},
+	{HV_X64_REGISTER_MSR_MTRR_FIX64K00000, -1, MSR_MTRRfix64K_00000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX16K80000, -1, MSR_MTRRfix16K_80000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX16KA0000, -1, MSR_MTRRfix16K_A0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KC0000, -1, MSR_MTRRfix4K_C0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KC8000, -1, MSR_MTRRfix4K_C8000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KD0000, -1, MSR_MTRRfix4K_D0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KD8000, -1, MSR_MTRRfix4K_D8000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KE0000, -1, MSR_MTRRfix4K_E0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KE8000, -1, MSR_MTRRfix4K_E8000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KF0000, -1, MSR_MTRRfix4K_F0000},
+	{HV_X64_REGISTER_MSR_MTRR_FIX4KF8000, -1, MSR_MTRRfix4K_F8000},
+};
+
+static int mshv_vtl_get_set_reg(struct hv_register_assoc *regs, bool set)
+{
+	u64 *reg64;
+	enum hv_register_name gpr_name;
+	int i;
+
+	gpr_name = regs->name;
+	reg64 = &regs->value.reg64;
+
+	/* Search for the register in the table */
+	for (i = 0; i < ARRAY_SIZE(reg_table); i++) {
+		if (reg_table[i].reg_name != gpr_name)
+			continue;
+		if (reg_table[i].debug_reg_num != -1) {
+			/* Handle debug registers */
+			if (gpr_name == HV_X64_REGISTER_DR6 &&
+			    !mshv_vsm_capabilities.dr6_shared)
+				goto hypercall;
+			if (set)
+				native_set_debugreg(reg_table[i].debug_reg_num, *reg64);
+			else
+				*reg64 = native_get_debugreg(reg_table[i].debug_reg_num);
+		} else {
+			/* Handle MSRs */
+			if (set)
+				wrmsrq(reg_table[i].msr_addr, *reg64);
+			else
+				rdmsrq(reg_table[i].msr_addr, *reg64);
+		}
+		return 0;
+	}
+
+hypercall:
+	return 1;
+}
+
+static void mshv_vtl_return(struct mshv_vtl_cpu_context *vtl0)
+{
+	struct hv_vp_assist_page *hvp;
+
+	hvp = hv_vp_assist_page[smp_processor_id()];
+
+	/*
+	 * Process signal event direct set in the run page, if any.
+	 */
+	if (mshv_vsm_capabilities.return_action_available) {
+		u32 offset = READ_ONCE(mshv_vtl_this_run()->vtl_ret_action_size);
+
+		WRITE_ONCE(mshv_vtl_this_run()->vtl_ret_action_size, 0);
+
+		/*
+		 * Hypervisor will take care of clearing out the actions
+		 * set in the assist page.
+		 */
+		memcpy(hvp->vtl_ret_actions,
+		       mshv_vtl_this_run()->vtl_ret_actions,
+		       min_t(u32, offset, sizeof(hvp->vtl_ret_actions)));
+	}
+
+	mshv_vtl_return_call(vtl0);
+}
+
+static bool mshv_vtl_process_intercept(void)
+{
+	struct hv_per_cpu_context *mshv_cpu;
+	void *synic_message_page;
+	struct hv_message *msg;
+	u32 message_type;
+
+	mshv_cpu = this_cpu_ptr(hv_context.cpu_context);
+	synic_message_page = mshv_cpu->hyp_synic_message_page;
+	if (unlikely(!synic_message_page))
+		return true;
+
+	msg = (struct hv_message *)synic_message_page + HV_SYNIC_INTERCEPTION_SINT_INDEX;
+	message_type = READ_ONCE(msg->header.message_type);
+	if (message_type == HVMSG_NONE)
+		return true;
+
+	memcpy(mshv_vtl_this_run()->exit_message, msg, sizeof(*msg));
+	vmbus_signal_eom(msg, message_type);
+
+	return false;
+}
+
+static int mshv_vtl_ioctl_return_to_lower_vtl(void)
+{
+	preempt_disable();
+	for (;;) {
+		unsigned long irq_flags;
+		struct hv_vp_assist_page *hvp;
+		int ret;
+
+		if (__xfer_to_guest_mode_work_pending()) {
+			preempt_enable();
+			ret = xfer_to_guest_mode_handle_work();
+			if (ret)
+				return ret;
+			preempt_disable();
+		}
+
+		local_irq_save(irq_flags);
+		if (READ_ONCE(mshv_vtl_this_run()->cancel)) {
+			local_irq_restore(irq_flags);
+			preempt_enable();
+			return -EINTR;
+		}
+
+		mshv_vtl_return(&mshv_vtl_this_run()->cpu_context);
+		local_irq_restore(irq_flags);
+
+		hvp = hv_vp_assist_page[smp_processor_id()];
+		this_cpu_inc(num_vtl0_transitions);
+		switch (hvp->vtl_entry_reason) {
+		case MSHV_ENTRY_REASON_INTERRUPT:
+			if (!mshv_vsm_capabilities.intercept_page_available &&
+			    likely(!mshv_vtl_process_intercept()))
+				goto done;
+			break;
+
+		case MSHV_ENTRY_REASON_INTERCEPT:
+			WARN_ON(!mshv_vsm_capabilities.intercept_page_available);
+			memcpy(mshv_vtl_this_run()->exit_message, hvp->intercept_message,
+			       sizeof(hvp->intercept_message));
+			goto done;
+
+		default:
+			panic("unknown entry reason: %d", hvp->vtl_entry_reason);
+		}
+	}
+
+done:
+	preempt_enable();
+
+	return 0;
+}
+
+static long
+mshv_vtl_ioctl_get_regs(void __user *user_args)
+{
+	struct mshv_vp_registers args;
+	struct hv_register_assoc reg;
+	long ret;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	/*  This IOCTL supports processing only one register at a time. */
+	if (args.count != 1)
+		return -EINVAL;
+
+	if (copy_from_user(&reg, (void __user *)args.regs_ptr,
+			   sizeof(reg)))
+		return -EFAULT;
+
+	ret = mshv_vtl_get_set_reg(&reg, false);
+	if (!ret)
+		goto copy_args; /* No need of hypercall */
+	ret = vtl_get_vp_register(&reg);
+	if (ret)
+		return ret;
+
+copy_args:
+	if (copy_to_user((void __user *)args.regs_ptr, &reg, sizeof(reg)))
+		ret = -EFAULT;
+
+	return ret;
+}
+
+static long
+mshv_vtl_ioctl_set_regs(void __user *user_args)
+{
+	struct mshv_vp_registers args;
+	struct hv_register_assoc reg;
+	long ret;
+
+	if (copy_from_user(&args, user_args, sizeof(args)))
+		return -EFAULT;
+
+	/*  This IOCTL supports processing only one register at a time. */
+	if (args.count != 1)
+		return -EINVAL;
+
+	if (copy_from_user(&reg, (void __user *)args.regs_ptr, sizeof(reg)))
+		return -EFAULT;
+
+	ret = mshv_vtl_get_set_reg(&reg, true);
+	if (!ret)
+		return ret; /* No need of hypercall */
+	ret = vtl_set_vp_register(&reg);
+
+	return ret;
+}
+
+static long
+mshv_vtl_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	long ret;
+	struct mshv_vtl *vtl = filp->private_data;
+
+	switch (ioctl) {
+	case MSHV_SET_POLL_FILE:
+		ret = mshv_vtl_ioctl_set_poll_file((struct mshv_vtl_set_poll_file __user *)arg);
+		break;
+	case MSHV_GET_VP_REGISTERS:
+		ret = mshv_vtl_ioctl_get_regs((void __user *)arg);
+		break;
+	case MSHV_SET_VP_REGISTERS:
+		ret = mshv_vtl_ioctl_set_regs((void __user *)arg);
+		break;
+	case MSHV_RETURN_TO_LOWER_VTL:
+		ret = mshv_vtl_ioctl_return_to_lower_vtl();
+		break;
+	case MSHV_ADD_VTL0_MEMORY:
+		ret = mshv_vtl_ioctl_add_vtl0_mem(vtl, (void __user *)arg);
+		break;
+	default:
+		dev_err(vtl->module_dev, "invalid vtl ioctl: %#x\n", ioctl);
+		ret = -ENOTTY;
+	}
+
+	return ret;
+}
+
+static vm_fault_t mshv_vtl_fault(struct vm_fault *vmf)
+{
+	struct page *page;
+	int cpu = vmf->pgoff & MSHV_PG_OFF_CPU_MASK;
+	int real_off = vmf->pgoff >> MSHV_REAL_OFF_SHIFT;
+
+	if (cpu >= nr_cpu_ids || !cpu_online(cpu))
+		return VM_FAULT_SIGBUS;
+	/*
+	 * CPU Hotplug is not supported in VTL2 in OpenHCL, where this kernel driver exists.
+	 * CPU is expected to remain online after above cpu_online() check.
+	 */
+
+	if (real_off == MSHV_RUN_PAGE_OFFSET) {
+		page = virt_to_page(mshv_vtl_cpu_run(cpu));
+	} else if (real_off == MSHV_REG_PAGE_OFFSET) {
+		if (!mshv_has_reg_page)
+			return VM_FAULT_SIGBUS;
+		page = mshv_vtl_cpu_reg_page(cpu);
+	} else {
+		return VM_FAULT_NOPAGE;
+	}
+
+	get_page(page);
+	vmf->page = page;
+
+	return 0;
+}
+
+static const struct vm_operations_struct mshv_vtl_vm_ops = {
+	.fault = mshv_vtl_fault,
+};
+
+static int mshv_vtl_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &mshv_vtl_vm_ops;
+
+	return 0;
+}
+
+static int mshv_vtl_release(struct inode *inode, struct file *filp)
+{
+	struct mshv_vtl *vtl = filp->private_data;
+
+	kfree(vtl);
+
+	return 0;
+}
+
+static const struct file_operations mshv_vtl_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = mshv_vtl_ioctl,
+	.release = mshv_vtl_release,
+	.mmap = mshv_vtl_mmap,
+};
+
+static void mshv_vtl_synic_mask_vmbus_sint(void *info)
+{
+	union hv_synic_sint sint;
+	const u8 *mask = info;
+
+	sint.as_uint64 = 0;
+	sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+	sint.masked = (*mask != 0);
+	sint.auto_eoi = hv_recommend_using_aeoi();
+
+	hv_set_msr(HV_MSR_SINT0 + VTL2_VMBUS_SINT_INDEX,
+		   sint.as_uint64);
+
+	if (!sint.masked)
+		pr_debug("%s: Unmasking VTL2 VMBUS SINT on VP %d\n", __func__, smp_processor_id());
+	else
+		pr_debug("%s: Masking VTL2 VMBUS SINT on VP %d\n", __func__, smp_processor_id());
+}
+
+static void mshv_vtl_read_remote(void *buffer)
+{
+	struct hv_per_cpu_context *mshv_cpu = this_cpu_ptr(hv_context.cpu_context);
+	struct hv_message *msg = (struct hv_message *)mshv_cpu->hyp_synic_message_page +
+					VTL2_VMBUS_SINT_INDEX;
+	u32 message_type = READ_ONCE(msg->header.message_type);
+
+	WRITE_ONCE(has_message, false);
+	if (message_type == HVMSG_NONE)
+		return;
+
+	memcpy(buffer, msg, sizeof(*msg));
+	vmbus_signal_eom(msg, message_type);
+}
+
+static bool vtl_synic_mask_vmbus_sint_masked = true;
+
+static ssize_t mshv_vtl_sint_read(struct file *filp, char __user *arg, size_t size, loff_t *offset)
+{
+	struct hv_message msg = {};
+	int ret;
+
+	if (size < sizeof(msg))
+		return -EINVAL;
+
+	for (;;) {
+		smp_call_function_single(VMBUS_CONNECT_CPU, mshv_vtl_read_remote, &msg, true);
+		if (msg.header.message_type != HVMSG_NONE)
+			break;
+
+		if (READ_ONCE(vtl_synic_mask_vmbus_sint_masked))
+			return 0; /* EOF */
+
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		ret = wait_event_interruptible(fd_wait_queue,
+					       READ_ONCE(has_message) ||
+						READ_ONCE(vtl_synic_mask_vmbus_sint_masked));
+		if (ret)
+			return ret;
+	}
+
+	if (copy_to_user(arg, &msg, sizeof(msg)))
+		return -EFAULT;
+
+	return sizeof(msg);
+}
+
+static __poll_t mshv_vtl_sint_poll(struct file *filp, poll_table *wait)
+{
+	__poll_t mask = 0;
+
+	poll_wait(filp, &fd_wait_queue, wait);
+	if (READ_ONCE(has_message) || READ_ONCE(vtl_synic_mask_vmbus_sint_masked))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	return mask;
+}
+
+static void mshv_vtl_sint_on_msg_dpc(unsigned long data)
+{
+	WRITE_ONCE(has_message, true);
+	wake_up_interruptible_poll(&fd_wait_queue, EPOLLIN);
+}
+
+static int mshv_vtl_sint_ioctl_post_msg(struct mshv_vtl_sint_post_msg __user *arg)
+{
+	struct mshv_vtl_sint_post_msg message;
+	u8 payload[HV_MESSAGE_PAYLOAD_BYTE_COUNT];
+
+	if (copy_from_user(&message, arg, sizeof(message)))
+		return -EFAULT;
+	if (message.payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
+		return -EINVAL;
+	if (copy_from_user(payload, (void __user *)message.payload_ptr,
+			   message.payload_size))
+		return -EFAULT;
+
+	return hv_post_message((union hv_connection_id)message.connection_id,
+			       message.message_type, (void *)payload,
+			       message.payload_size);
+}
+
+static int mshv_vtl_sint_ioctl_signal_event(struct mshv_vtl_signal_event __user *arg)
+{
+	u64 input, status;
+	struct mshv_vtl_signal_event signal_event;
+
+	if (copy_from_user(&signal_event, arg, sizeof(signal_event)))
+		return -EFAULT;
+
+	input = signal_event.connection_id | ((u64)signal_event.flag << 32);
+
+	status = hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, input);
+
+	return hv_result_to_errno(status);
+}
+
+static int mshv_vtl_sint_ioctl_set_eventfd(struct mshv_vtl_set_eventfd __user *arg)
+{
+	struct mshv_vtl_set_eventfd set_eventfd;
+	struct eventfd_ctx *eventfd, *old_eventfd;
+
+	if (copy_from_user(&set_eventfd, arg, sizeof(set_eventfd)))
+		return -EFAULT;
+	if (set_eventfd.flag >= HV_EVENT_FLAGS_COUNT)
+		return -EINVAL;
+
+	eventfd = NULL;
+	if (set_eventfd.fd >= 0) {
+		eventfd = eventfd_ctx_fdget(set_eventfd.fd);
+		if (IS_ERR(eventfd))
+			return PTR_ERR(eventfd);
+	}
+
+	guard(mutex)(&flag_lock);
+	old_eventfd = READ_ONCE(flag_eventfds[set_eventfd.flag]);
+	WRITE_ONCE(flag_eventfds[set_eventfd.flag], eventfd);
+
+	if (old_eventfd) {
+		synchronize_rcu();
+		eventfd_ctx_put(old_eventfd);
+	}
+
+	return 0;
+}
+
+static int mshv_vtl_sint_ioctl_pause_msg_stream(struct mshv_sint_mask __user *arg)
+{
+	static DEFINE_MUTEX(vtl2_vmbus_sint_mask_mutex);
+	struct mshv_sint_mask mask;
+
+	if (copy_from_user(&mask, arg, sizeof(mask)))
+		return -EFAULT;
+	guard(mutex)(&vtl2_vmbus_sint_mask_mutex);
+	on_each_cpu(mshv_vtl_synic_mask_vmbus_sint, &mask.mask, 1);
+	WRITE_ONCE(vtl_synic_mask_vmbus_sint_masked, mask.mask != 0);
+	if (mask.mask)
+		wake_up_interruptible_poll(&fd_wait_queue, EPOLLIN);
+
+	return 0;
+}
+
+static long mshv_vtl_sint_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case MSHV_SINT_POST_MESSAGE:
+		return mshv_vtl_sint_ioctl_post_msg((struct mshv_vtl_sint_post_msg __user *)arg);
+	case MSHV_SINT_SIGNAL_EVENT:
+		return mshv_vtl_sint_ioctl_signal_event((struct mshv_vtl_signal_event __user *)arg);
+	case MSHV_SINT_SET_EVENTFD:
+		return mshv_vtl_sint_ioctl_set_eventfd((struct mshv_vtl_set_eventfd __user *)arg);
+	case MSHV_SINT_PAUSE_MESSAGE_STREAM:
+		return mshv_vtl_sint_ioctl_pause_msg_stream((struct mshv_sint_mask __user *)arg);
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+static const struct file_operations mshv_vtl_sint_ops = {
+	.owner = THIS_MODULE,
+	.read = mshv_vtl_sint_read,
+	.poll = mshv_vtl_sint_poll,
+	.unlocked_ioctl = mshv_vtl_sint_ioctl,
+};
+
+static struct miscdevice mshv_vtl_sint_dev = {
+	.name = "mshv_sint",
+	.fops = &mshv_vtl_sint_ops,
+	.mode = 0600,
+	.minor = MISC_DYNAMIC_MINOR,
+};
+
+static int mshv_vtl_hvcall_dev_open(struct inode *node, struct file *f)
+{
+	struct miscdevice *dev = f->private_data;
+	struct mshv_vtl_hvcall_fd *fd;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	fd = vzalloc(sizeof(*fd));
+	if (!fd)
+		return -ENOMEM;
+	fd->dev = dev;
+	f->private_data = fd;
+	mutex_init(&fd->init_mutex);
+
+	return 0;
+}
+
+static int mshv_vtl_hvcall_dev_release(struct inode *node, struct file *f)
+{
+	struct mshv_vtl_hvcall_fd *fd;
+
+	fd = f->private_data;
+	if (fd) {
+		vfree(fd);
+		f->private_data = NULL;
+	}
+
+	return 0;
+}
+
+static int mshv_vtl_hvcall_do_setup(struct mshv_vtl_hvcall_fd *fd,
+				    struct mshv_vtl_hvcall_setup __user *hvcall_setup_user)
+{
+	struct mshv_vtl_hvcall_setup hvcall_setup;
+
+	guard(mutex)(&fd->init_mutex);
+
+	if (fd->allow_map_initialized) {
+		dev_err(fd->dev->this_device,
+			"Hypercall allow map has already been set, pid %d\n",
+			current->pid);
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&hvcall_setup, hvcall_setup_user,
+			   sizeof(struct mshv_vtl_hvcall_setup))) {
+		return -EFAULT;
+	}
+	if (hvcall_setup.bitmap_array_size > ARRAY_SIZE(fd->allow_bitmap))
+		return -EINVAL;
+
+	if (copy_from_user(&fd->allow_bitmap,
+			   (void __user *)hvcall_setup.allow_bitmap_ptr,
+			   hvcall_setup.bitmap_array_size)) {
+		return -EFAULT;
+	}
+
+	dev_info(fd->dev->this_device, "Hypercall allow map has been set, pid %d\n",
+		 current->pid);
+	fd->allow_map_initialized = true;
+	return 0;
+}
+
+static bool mshv_vtl_hvcall_is_allowed(struct mshv_vtl_hvcall_fd *fd, u16 call_code)
+{
+	return test_bit(call_code, (unsigned long *)fd->allow_bitmap);
+}
+
+static int mshv_vtl_hvcall_call(struct mshv_vtl_hvcall_fd *fd,
+				struct mshv_vtl_hvcall __user *hvcall_user)
+{
+	struct mshv_vtl_hvcall hvcall;
+	void *in, *out;
+	int ret;
+
+	if (copy_from_user(&hvcall, hvcall_user, sizeof(struct mshv_vtl_hvcall)))
+		return -EFAULT;
+	if (hvcall.input_size > HV_HYP_PAGE_SIZE)
+		return -EINVAL;
+	if (hvcall.output_size > HV_HYP_PAGE_SIZE)
+		return -EINVAL;
+
+	/*
+	 * By default, all hypercalls are not allowed.
+	 * The user mode code has to set up the allow bitmap once.
+	 */
+
+	if (!mshv_vtl_hvcall_is_allowed(fd, hvcall.control & 0xFFFF)) {
+		dev_err(fd->dev->this_device,
+			"Hypercall with control data %#llx isn't allowed\n",
+			hvcall.control);
+		return -EPERM;
+	}
+
+	/*
+	 * This may create a problem for Confidential VM (CVM) usecase where we need to use
+	 * Hyper-V driver allocated per-cpu input and output pages (hyperv_pcpu_input_arg and
+	 * hyperv_pcpu_output_arg) for making a hypervisor call.
+	 *
+	 * TODO: Take care of this when CVM support is added.
+	 */
+	in = (void *)__get_free_page(GFP_KERNEL);
+	out = (void *)__get_free_page(GFP_KERNEL);
+	if (!in || !out) {
+		ret = -ENOMEM;
+		goto free_pages;
+	}
+
+	if (copy_from_user(in, (void __user *)hvcall.input_ptr, hvcall.input_size)) {
+		ret = -EFAULT;
+		goto free_pages;
+	}
+
+	/*
+	 * The caller supplies output_size, so clear the range copied back to
+	 * userspace in case the hypercall writes fewer bytes than requested.
+	 */
+	memset(out, 0, hvcall.output_size);
+
+	hvcall.status = hv_do_hypercall(hvcall.control, in, out);
+
+	if (copy_to_user((void __user *)hvcall.output_ptr, out, hvcall.output_size)) {
+		ret = -EFAULT;
+		goto free_pages;
+	}
+	ret = put_user(hvcall.status, &hvcall_user->status);
+free_pages:
+	free_page((unsigned long)in);
+	free_page((unsigned long)out);
+
+	return ret;
+}
+
+static long mshv_vtl_hvcall_dev_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
+{
+	struct mshv_vtl_hvcall_fd *fd = f->private_data;
+
+	switch (cmd) {
+	case MSHV_HVCALL_SETUP:
+		return mshv_vtl_hvcall_do_setup(fd, (struct mshv_vtl_hvcall_setup __user *)arg);
+	case MSHV_HVCALL:
+		return mshv_vtl_hvcall_call(fd, (struct mshv_vtl_hvcall __user *)arg);
+	default:
+		break;
+	}
+
+	return -ENOIOCTLCMD;
+}
+
+static const struct file_operations mshv_vtl_hvcall_dev_file_ops = {
+	.owner = THIS_MODULE,
+	.open = mshv_vtl_hvcall_dev_open,
+	.release = mshv_vtl_hvcall_dev_release,
+	.unlocked_ioctl = mshv_vtl_hvcall_dev_ioctl,
+};
+
+static struct miscdevice mshv_vtl_hvcall_dev = {
+	.name = "mshv_hvcall",
+	.nodename = "mshv_hvcall",
+	.fops = &mshv_vtl_hvcall_dev_file_ops,
+	.mode = 0600,
+	.minor = MISC_DYNAMIC_MINOR,
+};
+
+static int mshv_vtl_low_open(struct inode *inodep, struct file *filp)
+{
+	pid_t pid = task_pid_vnr(current);
+	uid_t uid = current_uid().val;
+	int ret = 0;
+
+	pr_debug("%s: Opening VTL low, task group %d, uid %d\n", __func__, pid, uid);
+
+	if (capable(CAP_SYS_ADMIN)) {
+		filp->private_data = inodep;
+	} else {
+		pr_err("%s: VTL low open failed: CAP_SYS_ADMIN required. task group %d, uid %d",
+		       __func__, pid, uid);
+		ret = -EPERM;
+	}
+
+	return ret;
+}
+
+static bool can_fault(struct vm_fault *vmf, unsigned long size, unsigned long *pfn)
+{
+	unsigned long mask = size - 1;
+	unsigned long start = vmf->address & ~mask;
+	unsigned long end = start + size;
+	bool is_valid;
+
+	is_valid = (vmf->address & mask) == ((vmf->pgoff << PAGE_SHIFT) & mask) &&
+		start >= vmf->vma->vm_start &&
+		end <= vmf->vma->vm_end;
+
+	if (is_valid)
+		*pfn = vmf->pgoff & ~(mask >> PAGE_SHIFT);
+
+	return is_valid;
+}
+
+static vm_fault_t mshv_vtl_low_huge_fault(struct vm_fault *vmf, unsigned int order)
+{
+	unsigned long pfn = vmf->pgoff;
+	vm_fault_t ret = VM_FAULT_FALLBACK;
+
+	switch (order) {
+	case 0:
+		return vmf_insert_mixed(vmf->vma, vmf->address, pfn);
+
+	case PMD_ORDER:
+		if (can_fault(vmf, PMD_SIZE, &pfn))
+			ret = vmf_insert_pfn_pmd(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
+		return ret;
+
+	case PUD_ORDER:
+		if (can_fault(vmf, PUD_SIZE, &pfn))
+			ret = vmf_insert_pfn_pud(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
+		return ret;
+
+	default:
+		return VM_FAULT_SIGBUS;
+	}
+}
+
+static vm_fault_t mshv_vtl_low_fault(struct vm_fault *vmf)
+{
+	return mshv_vtl_low_huge_fault(vmf, 0);
+}
+
+static const struct vm_operations_struct mshv_vtl_low_vm_ops = {
+	.fault = mshv_vtl_low_fault,
+	.huge_fault = mshv_vtl_low_huge_fault,
+};
+
+static int mshv_vtl_low_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &mshv_vtl_low_vm_ops;
+	vm_flags_set(vma, VM_HUGEPAGE | VM_MIXEDMAP);
+
+	return 0;
+}
+
+static const struct file_operations mshv_vtl_low_file_ops = {
+	.owner		= THIS_MODULE,
+	.open		= mshv_vtl_low_open,
+	.mmap		= mshv_vtl_low_mmap,
+};
+
+static struct miscdevice mshv_vtl_low = {
+	.name = "mshv_vtl_low",
+	.nodename = "mshv_vtl_low",
+	.fops = &mshv_vtl_low_file_ops,
+	.mode = 0600,
+	.minor = MISC_DYNAMIC_MINOR,
+};
+
+static int __init mshv_vtl_init(void)
+{
+	int ret;
+	struct device *dev = mshv_dev.this_device;
+
+	/*
+	 * This creates /dev/mshv which provides functionality to create VTLs and partitions.
+	 */
+	ret = misc_register(&mshv_dev);
+	if (ret) {
+		dev_err(dev, "mshv device register failed: %d\n", ret);
+		goto free_dev;
+	}
+
+	tasklet_init(&msg_dpc, mshv_vtl_sint_on_msg_dpc, 0);
+	init_waitqueue_head(&fd_wait_queue);
+
+	if (mshv_vtl_get_vsm_regs()) {
+		dev_emerg(dev, "Unable to get VSM capabilities !!\n");
+		ret = -ENODEV;
+		goto free_dev;
+	}
+	if (mshv_vtl_configure_vsm_partition(dev)) {
+		dev_emerg(dev, "VSM configuration failed !!\n");
+		ret = -ENODEV;
+		goto free_dev;
+	}
+
+	mshv_vtl_return_call_init(mshv_vsm_page_offsets.vtl_return_offset);
+	ret = hv_vtl_setup_synic();
+	if (ret)
+		goto free_dev;
+
+	/*
+	 * mshv_sint device adds VMBus relay ioctl support.
+	 * This provides a channel for VTL0 to communicate with VTL2.
+	 */
+	ret = misc_register(&mshv_vtl_sint_dev);
+	if (ret)
+		goto free_synic;
+
+	/*
+	 * mshv_hvcall device adds interface to enable userspace for direct hypercalls support.
+	 */
+	ret = misc_register(&mshv_vtl_hvcall_dev);
+	if (ret)
+		goto free_sint;
+
+	/*
+	 * mshv_vtl_low device is used to map VTL0 address space to a user-mode process in VTL2.
+	 * It implements mmap() to allow a user-mode process in VTL2 to map to the address of VTL0.
+	 */
+	ret = misc_register(&mshv_vtl_low);
+	if (ret)
+		goto free_hvcall;
+
+	/*
+	 * "mshv vtl mem dev" device is later used to setup VTL0 memory.
+	 */
+	mem_dev = kzalloc_obj(*mem_dev);
+	if (!mem_dev) {
+		ret = -ENOMEM;
+		goto free_low;
+	}
+
+	mutex_init(&mshv_vtl_poll_file_lock);
+
+	device_initialize(mem_dev);
+	dev_set_name(mem_dev, "mshv vtl mem dev");
+	ret = device_add(mem_dev);
+	if (ret) {
+		dev_err(dev, "mshv vtl mem dev add: %d\n", ret);
+		goto free_mem;
+	}
+
+	return 0;
+
+free_mem:
+	kfree(mem_dev);
+free_low:
+	misc_deregister(&mshv_vtl_low);
+free_hvcall:
+	misc_deregister(&mshv_vtl_hvcall_dev);
+free_sint:
+	misc_deregister(&mshv_vtl_sint_dev);
+free_synic:
+	hv_vtl_remove_synic();
+free_dev:
+	misc_deregister(&mshv_dev);
+
+	return ret;
+}
+
+static void __exit mshv_vtl_exit(void)
+{
+	device_del(mem_dev);
+	kfree(mem_dev);
+	misc_deregister(&mshv_vtl_low);
+	misc_deregister(&mshv_vtl_hvcall_dev);
+	misc_deregister(&mshv_vtl_sint_dev);
+	hv_vtl_remove_synic();
+	misc_deregister(&mshv_dev);
+}
+
+module_init(mshv_vtl_init);
+module_exit(mshv_vtl_exit);
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
new file mode 100644
index 000000000..592a9601f
--- /dev/null
+++ b/drivers/hv/ring_buffer.c
@@ -0,0 +1,654 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/hyperv.h>
+#include <linux/uio.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/prefetch.h>
+#include <linux/io.h>
+#include <linux/export.h>
+#include <asm/mshyperv.h>
+
+#include "hyperv_vmbus.h"
+
+#define VMBUS_PKT_TRAILER	8
+
+/*
+ * When we write to the ring buffer, check if the host needs to
+ * be signaled. Here is the details of this protocol:
+ *
+ *	1. The host guarantees that while it is draining the
+ *	   ring buffer, it will set the interrupt_mask to
+ *	   indicate it does not need to be interrupted when
+ *	   new data is placed.
+ *
+ *	2. The host guarantees that it will completely drain
+ *	   the ring buffer before exiting the read loop. Further,
+ *	   once the ring buffer is empty, it will clear the
+ *	   interrupt_mask and re-check to see if new data has
+ *	   arrived.
+ *
+ * KYS: Oct. 30, 2016:
+ * It looks like Windows hosts have logic to deal with DOS attacks that
+ * can be triggered if it receives interrupts when it is not expecting
+ * the interrupt. The host expects interrupts only when the ring
+ * transitions from empty to non-empty (or full to non full on the guest
+ * to host ring).
+ * So, base the signaling decision solely on the ring state until the
+ * host logic is fixed.
+ */
+
+static void hv_signal_on_write(u32 old_write, struct vmbus_channel *channel)
+{
+	struct hv_ring_buffer_info *rbi = &channel->outbound;
+
+	virt_mb();
+	if (READ_ONCE(rbi->ring_buffer->interrupt_mask))
+		return;
+
+	/* check interrupt_mask before read_index */
+	virt_rmb();
+	/*
+	 * This is the only case we need to signal when the
+	 * ring transitions from being empty to non-empty.
+	 */
+	if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) {
+		++channel->intr_out_empty;
+		vmbus_setevent(channel);
+	}
+}
+
+/* Get the next write location for the specified ring buffer. */
+static inline u32
+hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
+{
+	u32 next = ring_info->ring_buffer->write_index;
+
+	return next;
+}
+
+/* Set the next write location for the specified ring buffer. */
+static inline void
+hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
+		     u32 next_write_location)
+{
+	ring_info->ring_buffer->write_index = next_write_location;
+}
+
+/* Get the size of the ring buffer. */
+static inline u32
+hv_get_ring_buffersize(const struct hv_ring_buffer_info *ring_info)
+{
+	return ring_info->ring_datasize;
+}
+
+/* Get the read and write indices as u64 of the specified ring buffer. */
+static inline u64
+hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
+{
+	return (u64)ring_info->ring_buffer->write_index << 32;
+}
+
+/*
+ * Helper routine to copy from source to ring buffer.
+ * Assume there is enough room. Handles wrap-around in dest case only!!
+ */
+static u32 hv_copyto_ringbuffer(
+	struct hv_ring_buffer_info	*ring_info,
+	u32				start_write_offset,
+	const void			*src,
+	u32				srclen)
+{
+	void *ring_buffer = hv_get_ring_buffer(ring_info);
+	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
+
+	memcpy(ring_buffer + start_write_offset, src, srclen);
+
+	start_write_offset += srclen;
+	if (start_write_offset >= ring_buffer_size)
+		start_write_offset -= ring_buffer_size;
+
+	return start_write_offset;
+}
+
+/*
+ *
+ * hv_get_ringbuffer_availbytes()
+ *
+ * Get number of bytes available to read and to write to
+ * for the specified ring buffer
+ */
+static void
+hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
+			     u32 *read, u32 *write)
+{
+	u32 read_loc, write_loc, dsize;
+
+	/* Capture the read/write indices before they changed */
+	read_loc = READ_ONCE(rbi->ring_buffer->read_index);
+	write_loc = READ_ONCE(rbi->ring_buffer->write_index);
+	dsize = rbi->ring_datasize;
+
+	*write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
+		read_loc - write_loc;
+	*read = dsize - *write;
+}
+
+/* Get various debug metrics for the specified ring buffer. */
+int hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
+				struct hv_ring_buffer_debug_info *debug_info)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+
+	mutex_lock(&ring_info->ring_buffer_mutex);
+
+	if (!ring_info->ring_buffer) {
+		mutex_unlock(&ring_info->ring_buffer_mutex);
+		return -EINVAL;
+	}
+
+	hv_get_ringbuffer_availbytes(ring_info,
+				     &bytes_avail_toread,
+				     &bytes_avail_towrite);
+	debug_info->bytes_avail_toread = bytes_avail_toread;
+	debug_info->bytes_avail_towrite = bytes_avail_towrite;
+	debug_info->current_read_index = ring_info->ring_buffer->read_index;
+	debug_info->current_write_index = ring_info->ring_buffer->write_index;
+	debug_info->current_interrupt_mask
+		= ring_info->ring_buffer->interrupt_mask;
+	mutex_unlock(&ring_info->ring_buffer_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo);
+
+/* Initialize a channel's ring buffer info mutex locks */
+void hv_ringbuffer_pre_init(struct vmbus_channel *channel)
+{
+	mutex_init(&channel->inbound.ring_buffer_mutex);
+	mutex_init(&channel->outbound.ring_buffer_mutex);
+}
+
+/* Initialize the ring buffer. */
+int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
+		       struct page *pages, u32 page_cnt, u32 max_pkt_size,
+			   bool confidential)
+{
+	struct page **pages_wraparound;
+	int i;
+
+	BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));
+
+	/*
+	 * First page holds struct hv_ring_buffer, do wraparound mapping for
+	 * the rest.
+	 */
+	pages_wraparound = kzalloc_objs(struct page *, page_cnt * 2 - 1);
+	if (!pages_wraparound)
+		return -ENOMEM;
+
+	pages_wraparound[0] = pages;
+	for (i = 0; i < 2 * (page_cnt - 1); i++)
+		pages_wraparound[i + 1] =
+			&pages[i % (page_cnt - 1) + 1];
+
+	ring_info->ring_buffer = (struct hv_ring_buffer *)
+		vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
+			confidential ? PAGE_KERNEL : pgprot_decrypted(PAGE_KERNEL));
+
+	kfree(pages_wraparound);
+	if (!ring_info->ring_buffer)
+		return -ENOMEM;
+
+	/*
+	 * Ensure the header page is zero'ed since
+	 * encryption status may have changed.
+	 */
+	memset(ring_info->ring_buffer, 0, HV_HYP_PAGE_SIZE);
+
+	ring_info->ring_buffer->read_index =
+		ring_info->ring_buffer->write_index = 0;
+
+	/* Set the feature bit for enabling flow control. */
+	ring_info->ring_buffer->feature_bits.value = 1;
+
+	ring_info->ring_size = page_cnt << PAGE_SHIFT;
+	ring_info->ring_size_div10_reciprocal =
+		reciprocal_value(ring_info->ring_size / 10);
+	ring_info->ring_datasize = ring_info->ring_size -
+		sizeof(struct hv_ring_buffer);
+	ring_info->priv_read_index = 0;
+
+	/* Initialize buffer that holds copies of incoming packets */
+	if (max_pkt_size) {
+		ring_info->pkt_buffer = kzalloc(max_pkt_size, GFP_KERNEL);
+		if (!ring_info->pkt_buffer)
+			return -ENOMEM;
+		ring_info->pkt_buffer_size = max_pkt_size;
+	}
+
+	spin_lock_init(&ring_info->ring_lock);
+
+	return 0;
+}
+
+/* Cleanup the ring buffer. */
+void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
+{
+	mutex_lock(&ring_info->ring_buffer_mutex);
+	vunmap(ring_info->ring_buffer);
+	ring_info->ring_buffer = NULL;
+	mutex_unlock(&ring_info->ring_buffer_mutex);
+
+	kfree(ring_info->pkt_buffer);
+	ring_info->pkt_buffer = NULL;
+	ring_info->pkt_buffer_size = 0;
+}
+
+/*
+ * Check if the ring buffer spinlock is available to take or not; used on
+ * atomic contexts, like panic path (see the Hyper-V framebuffer driver).
+ */
+
+bool hv_ringbuffer_spinlock_busy(struct vmbus_channel *channel)
+{
+	struct hv_ring_buffer_info *rinfo = &channel->outbound;
+
+	return spin_is_locked(&rinfo->ring_lock);
+}
+EXPORT_SYMBOL_GPL(hv_ringbuffer_spinlock_busy);
+
+/* Write to the ring buffer. */
+int hv_ringbuffer_write(struct vmbus_channel *channel,
+			const struct kvec *kv_list, u32 kv_count,
+			u64 requestid, u64 *trans_id)
+{
+	int i;
+	u32 bytes_avail_towrite;
+	u32 totalbytes_towrite = sizeof(u64);
+	u32 next_write_location;
+	u32 old_write;
+	u64 prev_indices;
+	unsigned long flags;
+	struct hv_ring_buffer_info *outring_info = &channel->outbound;
+	struct vmpacket_descriptor *desc = kv_list[0].iov_base;
+	u64 __trans_id, rqst_id = VMBUS_NO_RQSTOR;
+
+	if (channel->rescind)
+		return -ENODEV;
+
+	for (i = 0; i < kv_count; i++)
+		totalbytes_towrite += kv_list[i].iov_len;
+
+	spin_lock_irqsave(&outring_info->ring_lock, flags);
+
+	bytes_avail_towrite = hv_get_bytes_to_write(outring_info);
+
+	/*
+	 * If there is only room for the packet, assume it is full.
+	 * Otherwise, the next time around, we think the ring buffer
+	 * is empty since the read index == write index.
+	 */
+	if (bytes_avail_towrite <= totalbytes_towrite) {
+		++channel->out_full_total;
+
+		if (!channel->out_full_flag) {
+			++channel->out_full_first;
+			channel->out_full_flag = true;
+		}
+
+		spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+		return -EAGAIN;
+	}
+
+	channel->out_full_flag = false;
+
+	/* Write to the ring buffer */
+	next_write_location = hv_get_next_write_location(outring_info);
+
+	old_write = next_write_location;
+
+	for (i = 0; i < kv_count; i++) {
+		next_write_location = hv_copyto_ringbuffer(outring_info,
+						     next_write_location,
+						     kv_list[i].iov_base,
+						     kv_list[i].iov_len);
+	}
+
+	/*
+	 * Allocate the request ID after the data has been copied into the
+	 * ring buffer.  Once this request ID is allocated, the completion
+	 * path could find the data and free it.
+	 */
+
+	if (desc->flags == VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED) {
+		if (channel->next_request_id_callback != NULL) {
+			rqst_id = channel->next_request_id_callback(channel, requestid);
+			if (rqst_id == VMBUS_RQST_ERROR) {
+				spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+				return -EAGAIN;
+			}
+		}
+	}
+	desc = hv_get_ring_buffer(outring_info) + old_write;
+	__trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id;
+	/*
+	 * Ensure the compiler doesn't generate code that reads the value of
+	 * the transaction ID from the ring buffer, which is shared with the
+	 * Hyper-V host and subject to being changed at any time.
+	 */
+	WRITE_ONCE(desc->trans_id, __trans_id);
+	if (trans_id)
+		*trans_id = __trans_id;
+
+	/* Set previous packet start */
+	prev_indices = hv_get_ring_bufferindices(outring_info);
+
+	next_write_location = hv_copyto_ringbuffer(outring_info,
+					     next_write_location,
+					     &prev_indices,
+					     sizeof(u64));
+
+	/* Issue a full memory barrier before updating the write index */
+	virt_mb();
+
+	/* Now, update the write location */
+	hv_set_next_write_location(outring_info, next_write_location);
+
+
+	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+
+	hv_signal_on_write(old_write, channel);
+
+	if (channel->rescind) {
+		if (rqst_id != VMBUS_NO_RQSTOR) {
+			/* Reclaim request ID to avoid leak of IDs */
+			if (channel->request_addr_callback != NULL)
+				channel->request_addr_callback(channel, rqst_id);
+		}
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+int hv_ringbuffer_read(struct vmbus_channel *channel,
+		       void *buffer, u32 buflen, u32 *buffer_actual_len,
+		       u64 *requestid, bool raw)
+{
+	struct vmpacket_descriptor *desc;
+	u32 packetlen, offset;
+
+	if (unlikely(buflen == 0))
+		return -EINVAL;
+
+	*buffer_actual_len = 0;
+	*requestid = 0;
+
+	/* Make sure there is something to read */
+	desc = hv_pkt_iter_first(channel);
+	if (desc == NULL) {
+		/*
+		 * No error is set when there is even no header, drivers are
+		 * supposed to analyze buffer_actual_len.
+		 */
+		return 0;
+	}
+
+	offset = raw ? 0 : (desc->offset8 << 3);
+	packetlen = (desc->len8 << 3) - offset;
+	*buffer_actual_len = packetlen;
+	*requestid = desc->trans_id;
+
+	if (unlikely(packetlen > buflen))
+		return -ENOBUFS;
+
+	/* since ring is double mapped, only one copy is necessary */
+	memcpy(buffer, (const char *)desc + offset, packetlen);
+
+	/* Advance ring index to next packet descriptor */
+	__hv_pkt_iter_next(channel, desc);
+
+	/* Notify host of update */
+	hv_pkt_iter_close(channel);
+
+	return 0;
+}
+
+/*
+ * Determine number of bytes available in ring buffer after
+ * the current iterator (priv_read_index) location.
+ *
+ * This is similar to hv_get_bytes_to_read but with private
+ * read index instead.
+ */
+static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
+{
+	u32 priv_read_loc = rbi->priv_read_index;
+	u32 write_loc;
+
+	/*
+	 * The Hyper-V host writes the packet data, then uses
+	 * store_release() to update the write_index.  Use load_acquire()
+	 * here to prevent loads of the packet data from being re-ordered
+	 * before the read of the write_index and potentially getting
+	 * stale data.
+	 */
+	write_loc = virt_load_acquire(&rbi->ring_buffer->write_index);
+
+	if (write_loc >= priv_read_loc)
+		return write_loc - priv_read_loc;
+	else
+		return (rbi->ring_datasize - priv_read_loc) + write_loc;
+}
+
+/*
+ * Get first vmbus packet from ring buffer after read_index
+ *
+ * If ring buffer is empty, returns NULL and no other action needed.
+ */
+struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
+{
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+	struct vmpacket_descriptor *desc, *desc_copy;
+	u32 bytes_avail, pkt_len, pkt_offset;
+
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
+
+	bytes_avail = hv_pkt_iter_avail(rbi);
+	if (bytes_avail < sizeof(struct vmpacket_descriptor))
+		return NULL;
+	bytes_avail = min(rbi->pkt_buffer_size, bytes_avail);
+
+	desc = (struct vmpacket_descriptor *)(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
+
+	/*
+	 * Ensure the compiler does not use references to incoming Hyper-V values (which
+	 * could change at any moment) when reading local variables later in the code
+	 */
+	pkt_len = READ_ONCE(desc->len8) << 3;
+	pkt_offset = READ_ONCE(desc->offset8) << 3;
+
+	/*
+	 * If pkt_len is invalid, set it to the smaller of hv_pkt_iter_avail() and
+	 * rbi->pkt_buffer_size
+	 */
+	if (pkt_len < sizeof(struct vmpacket_descriptor) || pkt_len > bytes_avail)
+		pkt_len = bytes_avail;
+
+	/*
+	 * If pkt_offset is invalid, arbitrarily set it to
+	 * the size of vmpacket_descriptor
+	 */
+	if (pkt_offset < sizeof(struct vmpacket_descriptor) || pkt_offset > pkt_len)
+		pkt_offset = sizeof(struct vmpacket_descriptor);
+
+	/* Copy the Hyper-V packet out of the ring buffer */
+	desc_copy = (struct vmpacket_descriptor *)rbi->pkt_buffer;
+	memcpy(desc_copy, desc, pkt_len);
+
+	/*
+	 * Hyper-V could still change len8 and offset8 after the earlier read.
+	 * Ensure that desc_copy has legal values for len8 and offset8 that
+	 * are consistent with the copy we just made
+	 */
+	desc_copy->len8 = pkt_len >> 3;
+	desc_copy->offset8 = pkt_offset >> 3;
+
+	return desc_copy;
+}
+EXPORT_SYMBOL_GPL(hv_pkt_iter_first);
+
+/*
+ * Get next vmbus packet from ring buffer.
+ *
+ * Advances the current location (priv_read_index) and checks for more
+ * data. If the end of the ring buffer is reached, then return NULL.
+ */
+struct vmpacket_descriptor *
+__hv_pkt_iter_next(struct vmbus_channel *channel,
+		   const struct vmpacket_descriptor *desc)
+{
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+	u32 packetlen = desc->len8 << 3;
+	u32 dsize = rbi->ring_datasize;
+
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
+	/* bump offset to next potential packet */
+	rbi->priv_read_index += packetlen + VMBUS_PKT_TRAILER;
+	if (rbi->priv_read_index >= dsize)
+		rbi->priv_read_index -= dsize;
+
+	/* more data? */
+	return hv_pkt_iter_first(channel);
+}
+EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
+
+/* How many bytes were read in this iterator cycle */
+static u32 hv_pkt_iter_bytes_read(const struct hv_ring_buffer_info *rbi,
+					u32 start_read_index)
+{
+	if (rbi->priv_read_index >= start_read_index)
+		return rbi->priv_read_index - start_read_index;
+	else
+		return rbi->ring_datasize - start_read_index +
+			rbi->priv_read_index;
+}
+
+/*
+ * Update host ring buffer after iterating over packets. If the host has
+ * stopped queuing new entries because it found the ring buffer full, and
+ * sufficient space is being freed up, signal the host. But be careful to
+ * only signal the host when necessary, both for performance reasons and
+ * because Hyper-V protects itself by throttling guests that signal
+ * inappropriately.
+ *
+ * Determining when to signal is tricky. There are three key data inputs
+ * that must be handled in this order to avoid race conditions:
+ *
+ * 1. Update the read_index
+ * 2. Read the pending_send_sz
+ * 3. Read the current write_index
+ *
+ * The interrupt_mask is not used to determine when to signal. The
+ * interrupt_mask is used only on the guest->host ring buffer when
+ * sending requests to the host. The host does not use it on the host->
+ * guest ring buffer to indicate whether it should be signaled.
+ */
+void hv_pkt_iter_close(struct vmbus_channel *channel)
+{
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+	u32 curr_write_sz, pending_sz, bytes_read, start_read_index;
+
+	/*
+	 * Make sure all reads are done before we update the read index since
+	 * the writer may start writing to the read area once the read index
+	 * is updated.
+	 */
+	virt_rmb();
+	start_read_index = rbi->ring_buffer->read_index;
+	rbi->ring_buffer->read_index = rbi->priv_read_index;
+
+	/*
+	 * Older versions of Hyper-V (before WS2102 and Win8) do not
+	 * implement pending_send_sz and simply poll if the host->guest
+	 * ring buffer is full.  No signaling is needed or expected.
+	 */
+	if (!rbi->ring_buffer->feature_bits.feat_pending_send_sz)
+		return;
+
+	/*
+	 * Issue a full memory barrier before making the signaling decision.
+	 * If reading pending_send_sz were to be reordered and happen
+	 * before we commit the new read_index, a race could occur.  If the
+	 * host were to set the pending_send_sz after we have sampled
+	 * pending_send_sz, and the ring buffer blocks before we commit the
+	 * read index, we could miss sending the interrupt. Issue a full
+	 * memory barrier to address this.
+	 */
+	virt_mb();
+
+	/*
+	 * If the pending_send_sz is zero, then the ring buffer is not
+	 * blocked and there is no need to signal.  This is far by the
+	 * most common case, so exit quickly for best performance.
+	 */
+	pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
+	if (!pending_sz)
+		return;
+
+	/*
+	 * Ensure the read of write_index in hv_get_bytes_to_write()
+	 * happens after the read of pending_send_sz.
+	 */
+	virt_rmb();
+	curr_write_sz = hv_get_bytes_to_write(rbi);
+	bytes_read = hv_pkt_iter_bytes_read(rbi, start_read_index);
+
+	/*
+	 * We want to signal the host only if we're transitioning
+	 * from a "not enough free space" state to a "enough free
+	 * space" state.  For example, it's possible that this function
+	 * could run and free up enough space to signal the host, and then
+	 * run again and free up additional space before the host has a
+	 * chance to clear the pending_send_sz.  The 2nd invocation would
+	 * be a null transition from "enough free space" to "enough free
+	 * space", which doesn't warrant a signal.
+	 *
+	 * Exactly filling the ring buffer is treated as "not enough
+	 * space". The ring buffer always must have at least one byte
+	 * empty so the empty and full conditions are distinguishable.
+	 * hv_get_bytes_to_write() doesn't fully tell the truth in
+	 * this regard.
+	 *
+	 * So first check if we were in the "enough free space" state
+	 * before we began the iteration. If so, the host was not
+	 * blocked, and there's no need to signal.
+	 */
+	if (curr_write_sz - bytes_read > pending_sz)
+		return;
+
+	/*
+	 * Similarly, if the new state is "not enough space", then
+	 * there's no need to signal.
+	 */
+	if (curr_write_sz <= pending_sz)
+		return;
+
+	++channel->intr_in_full;
+	vmbus_setevent(channel);
+}
+EXPORT_SYMBOL_GPL(hv_pkt_iter_close);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
new file mode 100644
index 000000000..5ebdbe24b
--- /dev/null
+++ b/drivers/hv/vmbus_drv.c
@@ -0,0 +1,3086 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/sysctl.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/completion.h>
+#include <linux/hyperv.h>
+#include <linux/kernel_stat.h>
+#include <linux/of_address.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/sched/isolation.h>
+#include <linux/sched/task_stack.h>
+#include <linux/smpboot.h>
+
+#include <linux/delay.h>
+#include <linux/panic_notifier.h>
+#include <linux/ptrace.h>
+#include <linux/sysfb.h>
+#include <linux/efi.h>
+#include <linux/kernel.h>
+#include <linux/syscore_ops.h>
+#include <linux/dma-map-ops.h>
+#include <linux/pci.h>
+#include <linux/export.h>
+#include <clocksource/hyperv_timer.h>
+#include <asm/mshyperv.h>
+#include "hyperv_vmbus.h"
+
+struct vmbus_dynid {
+	struct list_head node;
+	struct hv_vmbus_device_id id;
+};
+
+/* VMBus Root Device */
+static struct device  *vmbus_root_device;
+
+static int hyperv_cpuhp_online;
+
+static DEFINE_PER_CPU(long, vmbus_evt);
+
+/* Values parsed from ACPI DSDT */
+int vmbus_irq;
+int vmbus_interrupt;
+
+/*
+ * If the Confidential VMBus is used, the data on the "wire" is not
+ * visible to either the host or the hypervisor.
+ */
+static bool is_confidential;
+
+bool vmbus_is_confidential(void)
+{
+	return is_confidential;
+}
+EXPORT_SYMBOL_GPL(vmbus_is_confidential);
+
+static bool skip_vmbus_unload;
+
+/*
+ * Allow a VMBus framebuffer driver to specify that in the case of a panic,
+ * it will do the VMbus unload operation once it has flushed any dirty
+ * portions of the framebuffer to the Hyper-V host.
+ */
+void vmbus_set_skip_unload(bool skip)
+{
+	skip_vmbus_unload = skip;
+}
+EXPORT_SYMBOL_GPL(vmbus_set_skip_unload);
+
+/*
+ * The panic notifier below is responsible solely for unloading the
+ * vmbus connection, which is necessary in a panic event.
+ */
+static int hv_panic_vmbus_unload(struct notifier_block *nb, unsigned long val,
+			      void *args)
+{
+	if (!skip_vmbus_unload)
+		vmbus_initiate_unload(true);
+
+	return NOTIFY_DONE;
+}
+static struct notifier_block hyperv_panic_vmbus_unload_block = {
+	.notifier_call	= hv_panic_vmbus_unload,
+	.priority	= INT_MIN + 1, /* almost the latest one to execute */
+};
+
+static const char *fb_mmio_name = "fb_range";
+static struct resource *fb_mmio;
+static struct resource *hyperv_mmio;
+static DEFINE_MUTEX(hyperv_mmio_lock);
+
+struct device *hv_get_vmbus_root_device(void)
+{
+	return vmbus_root_device;
+}
+EXPORT_SYMBOL_GPL(hv_get_vmbus_root_device);
+
+bool hv_vmbus_exists(void)
+{
+	return vmbus_root_device != NULL;
+}
+EXPORT_SYMBOL_GPL(hv_vmbus_exists);
+
+static u8 channel_monitor_group(const struct vmbus_channel *channel)
+{
+	return (u8)channel->offermsg.monitorid / 32;
+}
+
+static u8 channel_monitor_offset(const struct vmbus_channel *channel)
+{
+	return (u8)channel->offermsg.monitorid % 32;
+}
+
+static u32 channel_pending(const struct vmbus_channel *channel,
+			   const struct hv_monitor_page *monitor_page)
+{
+	u8 monitor_group = channel_monitor_group(channel);
+
+	return monitor_page->trigger_group[monitor_group].pending;
+}
+
+static u32 channel_latency(const struct vmbus_channel *channel,
+			   const struct hv_monitor_page *monitor_page)
+{
+	u8 monitor_group = channel_monitor_group(channel);
+	u8 monitor_offset = channel_monitor_offset(channel);
+
+	return monitor_page->latency[monitor_group][monitor_offset];
+}
+
+static u32 channel_conn_id(struct vmbus_channel *channel,
+			   struct hv_monitor_page *monitor_page)
+{
+	u8 monitor_group = channel_monitor_group(channel);
+	u8 monitor_offset = channel_monitor_offset(channel);
+
+	return monitor_page->parameter[monitor_group][monitor_offset].connectionid.u.id;
+}
+
+static ssize_t id_show(struct device *dev, struct device_attribute *dev_attr,
+		       char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", hv_dev->channel->offermsg.child_relid);
+}
+static DEVICE_ATTR_RO(id);
+
+static ssize_t state_show(struct device *dev, struct device_attribute *dev_attr,
+			  char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", hv_dev->channel->state);
+}
+static DEVICE_ATTR_RO(state);
+
+static ssize_t monitor_id_show(struct device *dev,
+			       struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", hv_dev->channel->offermsg.monitorid);
+}
+static DEVICE_ATTR_RO(monitor_id);
+
+static ssize_t class_id_show(struct device *dev,
+			       struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "{%pUl}\n",
+			  &hv_dev->channel->offermsg.offer.if_type);
+}
+static DEVICE_ATTR_RO(class_id);
+
+static ssize_t device_id_show(struct device *dev,
+			      struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "{%pUl}\n",
+			  &hv_dev->channel->offermsg.offer.if_instance);
+}
+static DEVICE_ATTR_RO(device_id);
+
+static ssize_t modalias_show(struct device *dev,
+			     struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	return sysfs_emit(buf, "vmbus:%*phN\n", UUID_SIZE, &hv_dev->dev_type);
+}
+static DEVICE_ATTR_RO(modalias);
+
+#ifdef CONFIG_NUMA
+static ssize_t numa_node_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	return sysfs_emit(buf, "%d\n", cpu_to_node(hv_dev->channel->target_cpu));
+}
+static DEVICE_ATTR_RO(numa_node);
+#endif
+
+static ssize_t server_monitor_pending_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", channel_pending(hv_dev->channel,
+			  vmbus_connection.monitor_pages[0]));
+}
+static DEVICE_ATTR_RO(server_monitor_pending);
+
+static ssize_t client_monitor_pending_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", channel_pending(hv_dev->channel,
+			  vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(client_monitor_pending);
+
+static ssize_t server_monitor_latency_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", channel_latency(hv_dev->channel,
+			  vmbus_connection.monitor_pages[0]));
+}
+static DEVICE_ATTR_RO(server_monitor_latency);
+
+static ssize_t client_monitor_latency_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", channel_latency(hv_dev->channel,
+			  vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(client_monitor_latency);
+
+static ssize_t server_monitor_conn_id_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", channel_conn_id(hv_dev->channel,
+			  vmbus_connection.monitor_pages[0]));
+}
+static DEVICE_ATTR_RO(server_monitor_conn_id);
+
+static ssize_t client_monitor_conn_id_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sysfs_emit(buf, "%d\n", channel_conn_id(hv_dev->channel,
+			  vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(client_monitor_conn_id);
+
+static ssize_t out_intr_mask_show(struct device *dev,
+				  struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+					  &outbound);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", outbound.current_interrupt_mask);
+}
+static DEVICE_ATTR_RO(out_intr_mask);
+
+static ssize_t out_read_index_show(struct device *dev,
+				   struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+					  &outbound);
+	if (ret < 0)
+		return ret;
+	return sysfs_emit(buf, "%u\n", outbound.current_read_index);
+}
+static DEVICE_ATTR_RO(out_read_index);
+
+static ssize_t out_write_index_show(struct device *dev,
+				    struct device_attribute *dev_attr,
+				    char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+					  &outbound);
+	if (ret < 0)
+		return ret;
+	return sysfs_emit(buf, "%u\n", outbound.current_write_index);
+}
+static DEVICE_ATTR_RO(out_write_index);
+
+static ssize_t out_read_bytes_avail_show(struct device *dev,
+					 struct device_attribute *dev_attr,
+					 char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+					  &outbound);
+	if (ret < 0)
+		return ret;
+	return sysfs_emit(buf, "%d\n", outbound.bytes_avail_toread);
+}
+static DEVICE_ATTR_RO(out_read_bytes_avail);
+
+static ssize_t out_write_bytes_avail_show(struct device *dev,
+					  struct device_attribute *dev_attr,
+					  char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+					  &outbound);
+	if (ret < 0)
+		return ret;
+	return sysfs_emit(buf, "%d\n", outbound.bytes_avail_towrite);
+}
+static DEVICE_ATTR_RO(out_write_bytes_avail);
+
+static ssize_t in_intr_mask_show(struct device *dev,
+				 struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", inbound.current_interrupt_mask);
+}
+static DEVICE_ATTR_RO(in_intr_mask);
+
+static ssize_t in_read_index_show(struct device *dev,
+				  struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", inbound.current_read_index);
+}
+static DEVICE_ATTR_RO(in_read_index);
+
+static ssize_t in_write_index_show(struct device *dev,
+				   struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", inbound.current_write_index);
+}
+static DEVICE_ATTR_RO(in_write_index);
+
+static ssize_t in_read_bytes_avail_show(struct device *dev,
+					struct device_attribute *dev_attr,
+					char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", inbound.bytes_avail_toread);
+}
+static DEVICE_ATTR_RO(in_read_bytes_avail);
+
+static ssize_t in_write_bytes_avail_show(struct device *dev,
+					 struct device_attribute *dev_attr,
+					 char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+	int ret;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", inbound.bytes_avail_towrite);
+}
+static DEVICE_ATTR_RO(in_write_bytes_avail);
+
+static ssize_t channel_vp_mapping_show(struct device *dev,
+				       struct device_attribute *dev_attr,
+				       char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct vmbus_channel *channel = hv_dev->channel, *cur_sc;
+	int n_written;
+	struct list_head *cur;
+
+	if (!channel)
+		return -ENODEV;
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	n_written = sysfs_emit(buf, "%u:%u\n",
+			       channel->offermsg.child_relid,
+			       channel->target_cpu);
+
+	list_for_each(cur, &channel->sc_list) {
+
+		cur_sc = list_entry(cur, struct vmbus_channel, sc_list);
+		n_written += sysfs_emit_at(buf, n_written, "%u:%u\n",
+					  cur_sc->offermsg.child_relid,
+					  cur_sc->target_cpu);
+	}
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	return n_written;
+}
+static DEVICE_ATTR_RO(channel_vp_mapping);
+
+static ssize_t vendor_show(struct device *dev,
+			   struct device_attribute *dev_attr,
+			   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	return sysfs_emit(buf, "0x%x\n", hv_dev->vendor_id);
+}
+static DEVICE_ATTR_RO(vendor);
+
+static ssize_t device_show(struct device *dev,
+			   struct device_attribute *dev_attr,
+			   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	return sysfs_emit(buf, "0x%x\n", hv_dev->device_id);
+}
+static DEVICE_ATTR_RO(device);
+
+/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
+static struct attribute *vmbus_dev_attrs[] = {
+	&dev_attr_id.attr,
+	&dev_attr_state.attr,
+	&dev_attr_monitor_id.attr,
+	&dev_attr_class_id.attr,
+	&dev_attr_device_id.attr,
+	&dev_attr_modalias.attr,
+#ifdef CONFIG_NUMA
+	&dev_attr_numa_node.attr,
+#endif
+	&dev_attr_server_monitor_pending.attr,
+	&dev_attr_client_monitor_pending.attr,
+	&dev_attr_server_monitor_latency.attr,
+	&dev_attr_client_monitor_latency.attr,
+	&dev_attr_server_monitor_conn_id.attr,
+	&dev_attr_client_monitor_conn_id.attr,
+	&dev_attr_out_intr_mask.attr,
+	&dev_attr_out_read_index.attr,
+	&dev_attr_out_write_index.attr,
+	&dev_attr_out_read_bytes_avail.attr,
+	&dev_attr_out_write_bytes_avail.attr,
+	&dev_attr_in_intr_mask.attr,
+	&dev_attr_in_read_index.attr,
+	&dev_attr_in_write_index.attr,
+	&dev_attr_in_read_bytes_avail.attr,
+	&dev_attr_in_write_bytes_avail.attr,
+	&dev_attr_channel_vp_mapping.attr,
+	&dev_attr_vendor.attr,
+	&dev_attr_device.attr,
+	NULL,
+};
+
+/*
+ * Device-level attribute_group callback function. Returns the permission for
+ * each attribute, and returns 0 if an attribute is not visible.
+ */
+static umode_t vmbus_dev_attr_is_visible(struct kobject *kobj,
+					 struct attribute *attr, int idx)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	const struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	/* Hide the monitor attributes if the monitor mechanism is not used. */
+	if (!hv_dev->channel->offermsg.monitor_allocated &&
+	    (attr == &dev_attr_monitor_id.attr ||
+	     attr == &dev_attr_server_monitor_pending.attr ||
+	     attr == &dev_attr_client_monitor_pending.attr ||
+	     attr == &dev_attr_server_monitor_latency.attr ||
+	     attr == &dev_attr_client_monitor_latency.attr ||
+	     attr == &dev_attr_server_monitor_conn_id.attr ||
+	     attr == &dev_attr_client_monitor_conn_id.attr))
+		return 0;
+
+	return attr->mode;
+}
+
+static const struct attribute_group vmbus_dev_group = {
+	.attrs = vmbus_dev_attrs,
+	.is_visible = vmbus_dev_attr_is_visible
+};
+__ATTRIBUTE_GROUPS(vmbus_dev);
+
+/* Set up the attribute for /sys/bus/vmbus/hibernation */
+static ssize_t hibernation_show(const struct bus_type *bus, char *buf)
+{
+	return sprintf(buf, "%d\n", !!hv_is_hibernation_supported());
+}
+
+static BUS_ATTR_RO(hibernation);
+
+static struct attribute *vmbus_bus_attrs[] = {
+	&bus_attr_hibernation.attr,
+	NULL,
+};
+static const struct attribute_group vmbus_bus_group = {
+	.attrs = vmbus_bus_attrs,
+};
+__ATTRIBUTE_GROUPS(vmbus_bus);
+
+/*
+ * vmbus_uevent - add uevent for our device
+ *
+ * This routine is invoked when a device is added or removed on the vmbus to
+ * generate a uevent to udev in the userspace. The udev will then look at its
+ * rule and the uevent generated here to load the appropriate driver
+ *
+ * The alias string will be of the form vmbus:guid where guid is the string
+ * representation of the device guid (each byte of the guid will be
+ * represented with two hex characters.
+ */
+static int vmbus_uevent(const struct device *device, struct kobj_uevent_env *env)
+{
+	const struct hv_device *dev = device_to_hv_device(device);
+	const char *format = "MODALIAS=vmbus:%*phN";
+
+	return add_uevent_var(env, format, UUID_SIZE, &dev->dev_type);
+}
+
+static const struct hv_vmbus_device_id *
+hv_vmbus_dev_match(const struct hv_vmbus_device_id *id, const guid_t *guid)
+{
+	if (id == NULL)
+		return NULL; /* empty device table */
+
+	for (; !guid_is_null(&id->guid); id++)
+		if (guid_equal(&id->guid, guid))
+			return id;
+
+	return NULL;
+}
+
+static const struct hv_vmbus_device_id *
+hv_vmbus_dynid_match(struct hv_driver *drv, const guid_t *guid)
+{
+	const struct hv_vmbus_device_id *id = NULL;
+	struct vmbus_dynid *dynid;
+
+	spin_lock(&drv->dynids.lock);
+	list_for_each_entry(dynid, &drv->dynids.list, node) {
+		if (guid_equal(&dynid->id.guid, guid)) {
+			id = &dynid->id;
+			break;
+		}
+	}
+	spin_unlock(&drv->dynids.lock);
+
+	return id;
+}
+
+static const struct hv_vmbus_device_id vmbus_device_null;
+
+/*
+ * Return a matching hv_vmbus_device_id pointer.
+ * If there is no match, return NULL.
+ */
+static const struct hv_vmbus_device_id *hv_vmbus_get_id(const struct hv_driver *drv,
+							struct hv_device *dev)
+{
+	const guid_t *guid = &dev->dev_type;
+	const struct hv_vmbus_device_id *id;
+	int ret;
+
+	/* If a driver override is set, only bind to the matching driver */
+	ret = device_match_driver_override(&dev->device, &drv->driver);
+	if (ret == 0)
+		return NULL;
+
+	/* Look at the dynamic ids first, before the static ones */
+	id = hv_vmbus_dynid_match((struct hv_driver *)drv, guid);
+	if (!id)
+		id = hv_vmbus_dev_match(drv->id_table, guid);
+
+	/*
+	 * If there's a matching driver override, this function should succeed,
+	 * thus return a dummy device ID if no matching ID is found.
+	 */
+	if (!id && ret > 0)
+		id = &vmbus_device_null;
+
+	return id;
+}
+
+/* vmbus_add_dynid - add a new device ID to this driver and re-probe devices
+ *
+ * This function can race with vmbus_device_register(). This function is
+ * typically running on a user thread in response to writing to the "new_id"
+ * sysfs entry for a driver. vmbus_device_register() is running on a
+ * workqueue thread in response to the Hyper-V host offering a device to the
+ * guest. This function calls driver_attach(), which looks for an existing
+ * device matching the new id, and attaches the driver to which the new id
+ * has been assigned. vmbus_device_register() calls device_register(), which
+ * looks for a driver that matches the device being registered. If both
+ * operations are running simultaneously, the device driver probe function runs
+ * on whichever thread establishes the linkage between the driver and device.
+ *
+ * In most cases, it doesn't matter which thread runs the driver probe
+ * function. But if vmbus_device_register() does not find a matching driver,
+ * it proceeds to create the "channels" subdirectory and numbered per-channel
+ * subdirectory in sysfs. While that multi-step creation is in progress, this
+ * function could run the driver probe function. If the probe function checks
+ * for, or operates on, entries in the "channels" subdirectory, including by
+ * calling hv_create_ring_sysfs(), the operation may or may not succeed
+ * depending on the race. The race can't create a kernel failure in VMBus
+ * or device subsystem code, but probe functions in VMBus drivers doing such
+ * operations must be prepared for the failure case.
+ */
+static int vmbus_add_dynid(struct hv_driver *drv, guid_t *guid)
+{
+	struct vmbus_dynid *dynid;
+
+	dynid = kzalloc_obj(*dynid);
+	if (!dynid)
+		return -ENOMEM;
+
+	dynid->id.guid = *guid;
+
+	spin_lock(&drv->dynids.lock);
+	list_add_tail(&dynid->node, &drv->dynids.list);
+	spin_unlock(&drv->dynids.lock);
+
+	return driver_attach(&drv->driver);
+}
+
+static void vmbus_free_dynids(struct hv_driver *drv)
+{
+	struct vmbus_dynid *dynid, *n;
+
+	spin_lock(&drv->dynids.lock);
+	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
+		list_del(&dynid->node);
+		kfree(dynid);
+	}
+	spin_unlock(&drv->dynids.lock);
+}
+
+/*
+ * store_new_id - sysfs frontend to vmbus_add_dynid()
+ *
+ * Allow GUIDs to be added to an existing driver via sysfs.
+ */
+static ssize_t new_id_store(struct device_driver *driver, const char *buf,
+			    size_t count)
+{
+	struct hv_driver *drv = drv_to_hv_drv(driver);
+	guid_t guid;
+	ssize_t retval;
+
+	retval = guid_parse(buf, &guid);
+	if (retval)
+		return retval;
+
+	if (hv_vmbus_dynid_match(drv, &guid))
+		return -EEXIST;
+
+	retval = vmbus_add_dynid(drv, &guid);
+	if (retval)
+		return retval;
+	return count;
+}
+static DRIVER_ATTR_WO(new_id);
+
+/*
+ * store_remove_id - remove a PCI device ID from this driver
+ *
+ * Removes a dynamic pci device ID to this driver.
+ */
+static ssize_t remove_id_store(struct device_driver *driver, const char *buf,
+			       size_t count)
+{
+	struct hv_driver *drv = drv_to_hv_drv(driver);
+	struct vmbus_dynid *dynid, *n;
+	guid_t guid;
+	ssize_t retval;
+
+	retval = guid_parse(buf, &guid);
+	if (retval)
+		return retval;
+
+	retval = -ENODEV;
+	spin_lock(&drv->dynids.lock);
+	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
+		struct hv_vmbus_device_id *id = &dynid->id;
+
+		if (guid_equal(&id->guid, &guid)) {
+			list_del(&dynid->node);
+			kfree(dynid);
+			retval = count;
+			break;
+		}
+	}
+	spin_unlock(&drv->dynids.lock);
+
+	return retval;
+}
+static DRIVER_ATTR_WO(remove_id);
+
+static struct attribute *vmbus_drv_attrs[] = {
+	&driver_attr_new_id.attr,
+	&driver_attr_remove_id.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(vmbus_drv);
+
+
+/*
+ * vmbus_match - Attempt to match the specified device to the specified driver
+ */
+static int vmbus_match(struct device *device, const struct device_driver *driver)
+{
+	const struct hv_driver *drv = drv_to_hv_drv(driver);
+	struct hv_device *hv_dev = device_to_hv_device(device);
+
+	/* The hv_sock driver handles all hv_sock offers. */
+	if (is_hvsock_channel(hv_dev->channel))
+		return drv->hvsock;
+
+	if (hv_vmbus_get_id(drv, hv_dev))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * vmbus_probe - Add the new vmbus's child device
+ */
+static int vmbus_probe(struct device *child_device)
+{
+	int ret = 0;
+	struct hv_driver *drv =
+			drv_to_hv_drv(child_device->driver);
+	struct hv_device *dev = device_to_hv_device(child_device);
+	const struct hv_vmbus_device_id *dev_id;
+
+	dev_id = hv_vmbus_get_id(drv, dev);
+	if (drv->probe) {
+		ret = drv->probe(dev, dev_id);
+		if (ret != 0)
+			pr_err("probe failed for device %s (%d)\n",
+			       dev_name(child_device), ret);
+
+	} else {
+		pr_err("probe not set for driver %s\n",
+		       dev_name(child_device));
+		ret = -ENODEV;
+	}
+	return ret;
+}
+
+/*
+ * vmbus_dma_configure -- Configure DMA coherence for VMbus device
+ */
+static int vmbus_dma_configure(struct device *child_device)
+{
+	/*
+	 * On ARM64, propagate the DMA coherence setting from the top level
+	 * VMbus ACPI device to the child VMbus device being added here.
+	 * On x86/x64 coherence is assumed and these calls have no effect.
+	 */
+	hv_setup_dma_ops(child_device,
+		device_get_dma_attr(vmbus_root_device) == DEV_DMA_COHERENT);
+	return 0;
+}
+
+/*
+ * vmbus_remove - Remove a vmbus device
+ */
+static void vmbus_remove(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+	if (child_device->driver) {
+		drv = drv_to_hv_drv(child_device->driver);
+		if (drv->remove)
+			drv->remove(dev);
+	}
+}
+
+/*
+ * vmbus_shutdown - Shutdown a vmbus device
+ */
+static void vmbus_shutdown(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+
+	/* The device may not be attached yet */
+	if (!child_device->driver)
+		return;
+
+	drv = drv_to_hv_drv(child_device->driver);
+
+	if (drv->shutdown)
+		drv->shutdown(dev);
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * vmbus_suspend - Suspend a vmbus device
+ */
+static int vmbus_suspend(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+	/* The device may not be attached yet */
+	if (!child_device->driver)
+		return 0;
+
+	drv = drv_to_hv_drv(child_device->driver);
+	if (!drv->suspend)
+		return -EOPNOTSUPP;
+
+	return drv->suspend(dev);
+}
+
+/*
+ * vmbus_resume - Resume a vmbus device
+ */
+static int vmbus_resume(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+	/* The device may not be attached yet */
+	if (!child_device->driver)
+		return 0;
+
+	drv = drv_to_hv_drv(child_device->driver);
+	if (!drv->resume)
+		return -EOPNOTSUPP;
+
+	return drv->resume(dev);
+}
+#else
+#define vmbus_suspend NULL
+#define vmbus_resume NULL
+#endif /* CONFIG_PM_SLEEP */
+
+/*
+ * vmbus_device_release - Final callback release of the vmbus child device
+ */
+static void vmbus_device_release(struct device *device)
+{
+	struct hv_device *hv_dev = device_to_hv_device(device);
+	struct vmbus_channel *channel = hv_dev->channel;
+
+	hv_debug_rm_dev_dir(hv_dev);
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+	hv_process_channel_removal(channel);
+	mutex_unlock(&vmbus_connection.channel_mutex);
+	kfree(hv_dev);
+}
+
+/*
+ * Note: we must use the "noirq" ops: see the comment before vmbus_bus_pm.
+ *
+ * suspend_noirq/resume_noirq are set to NULL to support Suspend-to-Idle: we
+ * shouldn't suspend the vmbus devices upon Suspend-to-Idle, otherwise there
+ * is no way to wake up a Generation-2 VM.
+ *
+ * The other 4 ops are for hibernation.
+ */
+
+static const struct dev_pm_ops vmbus_pm = {
+	.suspend_noirq	= NULL,
+	.resume_noirq	= NULL,
+	.freeze_noirq	= vmbus_suspend,
+	.thaw_noirq	= vmbus_resume,
+	.poweroff_noirq	= vmbus_suspend,
+	.restore_noirq	= vmbus_resume,
+};
+
+/* The one and only one */
+static const struct bus_type  hv_bus = {
+	.name =		"vmbus",
+	.driver_override =	true,
+	.match =		vmbus_match,
+	.shutdown =		vmbus_shutdown,
+	.remove =		vmbus_remove,
+	.probe =		vmbus_probe,
+	.uevent =		vmbus_uevent,
+	.dma_configure =	vmbus_dma_configure,
+	.dev_groups =		vmbus_dev_groups,
+	.drv_groups =		vmbus_drv_groups,
+	.bus_groups =		vmbus_bus_groups,
+	.pm =			&vmbus_pm,
+};
+
+struct onmessage_work_context {
+	struct work_struct work;
+	struct {
+		struct hv_message_header header;
+		u8 payload[];
+	} msg;
+};
+
+static void vmbus_onmessage_work(struct work_struct *work)
+{
+	struct onmessage_work_context *ctx;
+
+	/* Do not process messages if we're in DISCONNECTED state */
+	if (vmbus_connection.conn_state == DISCONNECTED)
+		return;
+
+	ctx = container_of(work, struct onmessage_work_context,
+			   work);
+	vmbus_onmessage((struct vmbus_channel_message_header *)
+			&ctx->msg.payload);
+	kfree(ctx);
+}
+
+static void __vmbus_on_msg_dpc(void *message_page_addr)
+{
+	struct hv_message msg_copy, *msg;
+	struct vmbus_channel_message_header *hdr;
+	enum vmbus_channel_message_type msgtype;
+	const struct vmbus_channel_message_table_entry *entry;
+	struct onmessage_work_context *ctx;
+	__u8 payload_size;
+	u32 message_type;
+
+	if (!message_page_addr)
+		return;
+	msg = (struct hv_message *)message_page_addr + VMBUS_MESSAGE_SINT;
+
+	/*
+	 * 'enum vmbus_channel_message_type' is supposed to always be 'u32' as
+	 * it is being used in 'struct vmbus_channel_message_header' definition
+	 * which is supposed to match hypervisor ABI.
+	 */
+	BUILD_BUG_ON(sizeof(enum vmbus_channel_message_type) != sizeof(u32));
+
+	/*
+	 * Since the message is in memory shared with the host, an erroneous or
+	 * malicious Hyper-V could modify the message while vmbus_on_msg_dpc()
+	 * or individual message handlers are executing; to prevent this, copy
+	 * the message into private memory.
+	 */
+	memcpy(&msg_copy, msg, sizeof(struct hv_message));
+
+	message_type = msg_copy.header.message_type;
+	if (message_type == HVMSG_NONE)
+		/* no msg */
+		return;
+
+	hdr = (struct vmbus_channel_message_header *)msg_copy.u.payload;
+	msgtype = hdr->msgtype;
+
+	trace_vmbus_on_msg_dpc(hdr);
+
+	if (msgtype >= CHANNELMSG_COUNT) {
+		WARN_ONCE(1, "unknown msgtype=%d\n", msgtype);
+		goto msg_handled;
+	}
+
+	payload_size = msg_copy.header.payload_size;
+	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT) {
+		WARN_ONCE(1, "payload size is too large (%d)\n", payload_size);
+		goto msg_handled;
+	}
+
+	entry = &channel_message_table[msgtype];
+
+	if (!entry->message_handler)
+		goto msg_handled;
+
+	if (payload_size < entry->min_payload_len) {
+		WARN_ONCE(1, "message too short: msgtype=%d len=%d\n", msgtype, payload_size);
+		goto msg_handled;
+	}
+
+	if (entry->handler_type	== VMHT_BLOCKING) {
+		ctx = kmalloc_flex(*ctx, msg.payload, payload_size, GFP_ATOMIC);
+		if (ctx == NULL)
+			return;
+
+		INIT_WORK(&ctx->work, vmbus_onmessage_work);
+		ctx->msg.header = msg_copy.header;
+		memcpy(&ctx->msg.payload, msg_copy.u.payload, payload_size);
+
+		/*
+		 * The host can generate a rescind message while we
+		 * may still be handling the original offer. We deal with
+		 * this condition by relying on the synchronization provided
+		 * by offer_in_progress and by channel_mutex.  See also the
+		 * inline comments in vmbus_onoffer_rescind().
+		 */
+		switch (msgtype) {
+		case CHANNELMSG_RESCIND_CHANNELOFFER:
+			/*
+			 * If we are handling the rescind message;
+			 * schedule the work on the global work queue.
+			 *
+			 * The OFFER message and the RESCIND message should
+			 * not be handled by the same serialized work queue,
+			 * because the OFFER handler may call vmbus_open(),
+			 * which tries to open the channel by sending an
+			 * OPEN_CHANNEL message to the host and waits for
+			 * the host's response; however, if the host has
+			 * rescinded the channel before it receives the
+			 * OPEN_CHANNEL message, the host just silently
+			 * ignores the OPEN_CHANNEL message; as a result,
+			 * the guest's OFFER handler hangs for ever, if we
+			 * handle the RESCIND message in the same serialized
+			 * work queue: the RESCIND handler can not start to
+			 * run before the OFFER handler finishes.
+			 */
+			if (vmbus_connection.ignore_any_offer_msg)
+				break;
+			queue_work(vmbus_connection.rescind_work_queue, &ctx->work);
+			break;
+
+		case CHANNELMSG_OFFERCHANNEL:
+			/*
+			 * The host sends the offer message of a given channel
+			 * before sending the rescind message of the same
+			 * channel.  These messages are sent to the guest's
+			 * connect CPU; the guest then starts processing them
+			 * in the tasklet handler on this CPU:
+			 *
+			 * VMBUS_CONNECT_CPU
+			 *
+			 * [vmbus_on_msg_dpc()]
+			 * atomic_inc()  // CHANNELMSG_OFFERCHANNEL
+			 * queue_work()
+			 * ...
+			 * [vmbus_on_msg_dpc()]
+			 * schedule_work()  // CHANNELMSG_RESCIND_CHANNELOFFER
+			 *
+			 * We rely on the memory-ordering properties of the
+			 * queue_work() and schedule_work() primitives, which
+			 * guarantee that the atomic increment will be visible
+			 * to the CPUs which will execute the offer & rescind
+			 * works by the time these works will start execution.
+			 */
+			if (vmbus_connection.ignore_any_offer_msg)
+				break;
+			atomic_inc(&vmbus_connection.offer_in_progress);
+			fallthrough;
+
+		default:
+			queue_work(vmbus_connection.work_queue, &ctx->work);
+		}
+	} else
+		entry->message_handler(hdr);
+
+msg_handled:
+	vmbus_signal_eom(msg, message_type);
+}
+
+void vmbus_on_msg_dpc(unsigned long data)
+{
+	struct hv_per_cpu_context *hv_cpu = (void *)data;
+
+	__vmbus_on_msg_dpc(hv_cpu->hyp_synic_message_page);
+	__vmbus_on_msg_dpc(hv_cpu->para_synic_message_page);
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * Fake RESCIND_CHANNEL messages to clean up hv_sock channels by force for
+ * hibernation, because hv_sock connections can not persist across hibernation.
+ */
+static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
+{
+	struct onmessage_work_context *ctx;
+	struct vmbus_channel_rescind_offer *rescind;
+
+	WARN_ON(!is_hvsock_channel(channel));
+
+	/*
+	 * Allocation size is small and the allocation should really not fail,
+	 * otherwise the state of the hv_sock connections ends up in limbo.
+	 */
+	ctx = kzalloc(sizeof(*ctx) + sizeof(*rescind),
+		      GFP_KERNEL | __GFP_NOFAIL);
+
+	/*
+	 * So far, these are not really used by Linux. Just set them to the
+	 * reasonable values conforming to the definitions of the fields.
+	 */
+	ctx->msg.header.message_type = 1;
+	ctx->msg.header.payload_size = sizeof(*rescind);
+
+	/* These values are actually used by Linux. */
+	rescind = (struct vmbus_channel_rescind_offer *)ctx->msg.payload;
+	rescind->header.msgtype = CHANNELMSG_RESCIND_CHANNELOFFER;
+	rescind->child_relid = channel->offermsg.child_relid;
+
+	INIT_WORK(&ctx->work, vmbus_onmessage_work);
+
+	queue_work(vmbus_connection.work_queue, &ctx->work);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+/*
+ * Schedule all channels with events pending.
+ * The event page can be directly checked to get the id of
+ * the channel that has the interrupt pending.
+ */
+static void vmbus_chan_sched(void *event_page_addr)
+{
+	unsigned long *recv_int_page;
+	u32 maxbits, relid;
+	union hv_synic_event_flags *event;
+
+	if (!event_page_addr)
+		return;
+	event = (union hv_synic_event_flags *)event_page_addr + VMBUS_MESSAGE_SINT;
+
+	maxbits = READ_ONCE(vmbus_connection.relid_hiwater) + 1;
+	recv_int_page = event->flags;
+
+	if (unlikely(!recv_int_page))
+		return;
+
+	for_each_set_bit(relid, recv_int_page, maxbits) {
+		void (*callback_fn)(void *context);
+		struct vmbus_channel *channel;
+
+		if (!sync_test_and_clear_bit(relid, recv_int_page))
+			continue;
+
+		/* Special case - vmbus channel protocol msg */
+		if (relid == 0)
+			continue;
+
+		/*
+		 * Pairs with the kfree_rcu() in vmbus_chan_release().
+		 * Guarantees that the channel data structure doesn't
+		 * get freed while the channel pointer below is being
+		 * dereferenced.
+		 */
+		rcu_read_lock();
+
+		/* Find channel based on relid */
+		channel = relid2channel(relid);
+		if (channel == NULL)
+			goto sched_unlock_rcu;
+
+		if (channel->rescind)
+			goto sched_unlock_rcu;
+
+		/*
+		 * Make sure that the ring buffer data structure doesn't get
+		 * freed while we dereference the ring buffer pointer.  Test
+		 * for the channel's onchannel_callback being NULL within a
+		 * sched_lock critical section.  See also the inline comments
+		 * in vmbus_reset_channel_cb().
+		 */
+		spin_lock(&channel->sched_lock);
+
+		callback_fn = channel->onchannel_callback;
+		if (unlikely(callback_fn == NULL))
+			goto sched_unlock;
+
+		trace_vmbus_chan_sched(channel);
+
+		++channel->interrupts;
+
+		switch (channel->callback_mode) {
+		case HV_CALL_ISR:
+			(*callback_fn)(channel->channel_callback_context);
+			break;
+
+		case HV_CALL_BATCHED:
+			hv_begin_read(&channel->inbound);
+			fallthrough;
+		case HV_CALL_DIRECT:
+			tasklet_schedule(&channel->callback_event);
+		}
+
+sched_unlock:
+		spin_unlock(&channel->sched_lock);
+sched_unlock_rcu:
+		rcu_read_unlock();
+	}
+}
+
+static void vmbus_message_sched(struct hv_per_cpu_context *hv_cpu, void *message_page_addr)
+{
+	struct hv_message *msg;
+
+	if (!message_page_addr)
+		return;
+	msg = (struct hv_message *)message_page_addr + VMBUS_MESSAGE_SINT;
+
+	/* Check if there are actual msgs to be processed */
+	if (msg->header.message_type != HVMSG_NONE)
+		tasklet_schedule(&hv_cpu->msg_dpc);
+}
+
+static void __vmbus_isr(void)
+{
+	struct hv_per_cpu_context *hv_cpu
+		= this_cpu_ptr(hv_context.cpu_context);
+
+	vmbus_chan_sched(hv_cpu->hyp_synic_event_page);
+	vmbus_chan_sched(hv_cpu->para_synic_event_page);
+
+	vmbus_message_sched(hv_cpu, hv_cpu->hyp_synic_message_page);
+	vmbus_message_sched(hv_cpu, hv_cpu->para_synic_message_page);
+}
+
+static DEFINE_PER_CPU(bool, vmbus_irq_pending);
+static DEFINE_PER_CPU(struct task_struct *, vmbus_irqd);
+
+static void vmbus_irqd_wake(void)
+{
+	struct task_struct *tsk = __this_cpu_read(vmbus_irqd);
+
+	__this_cpu_write(vmbus_irq_pending, true);
+	wake_up_process(tsk);
+}
+
+static void vmbus_irqd_setup(unsigned int cpu)
+{
+	sched_set_fifo(current);
+}
+
+static int vmbus_irqd_should_run(unsigned int cpu)
+{
+	return __this_cpu_read(vmbus_irq_pending);
+}
+
+static void run_vmbus_irqd(unsigned int cpu)
+{
+	__this_cpu_write(vmbus_irq_pending, false);
+	__vmbus_isr();
+}
+
+static struct smp_hotplug_thread vmbus_irq_threads = {
+	.store                  = &vmbus_irqd,
+	.setup			= vmbus_irqd_setup,
+	.thread_should_run      = vmbus_irqd_should_run,
+	.thread_fn              = run_vmbus_irqd,
+	.thread_comm            = "vmbus_irq/%u",
+};
+
+void vmbus_isr(void)
+{
+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		vmbus_irqd_wake();
+	} else {
+		static DEFINE_WAIT_OVERRIDE_MAP(vmbus_map, LD_WAIT_CONFIG);
+
+		/*
+		 * vmbus_isr is never force-threaded and always invoked at hard
+		 * IRQ level. __vmbus_isr() below can acquire a spinlock_t
+		 * which becomes a sleeping lock and must not be acquired in
+		 * this context. Therefore on PREEMPT_RT this will be threaded
+		 * via vmbus_irqd_wake(). On non-PREEMPT the annotation lets
+		 * lockdep know that acquiring a spinlock_t is not an issue.
+		 */
+		lock_map_acquire_try(&vmbus_map);
+		__vmbus_isr();
+		lock_map_release(&vmbus_map);
+	}
+}
+EXPORT_SYMBOL_FOR_MODULES(vmbus_isr, "mshv_vtl");
+
+static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
+{
+	vmbus_isr();
+	return IRQ_HANDLED;
+}
+
+static void vmbus_percpu_work(struct work_struct *work)
+{
+	unsigned int cpu = smp_processor_id();
+
+	hv_synic_init(cpu);
+}
+
+static int vmbus_alloc_synic_and_connect(void)
+{
+	int ret, cpu;
+	struct work_struct __percpu *works;
+
+	ret = hv_synic_alloc();
+	if (ret < 0)
+		goto err_alloc;
+
+	works = alloc_percpu(struct work_struct);
+	if (!works) {
+		ret = -ENOMEM;
+		goto err_alloc;
+	}
+
+	/*
+	 * Initialize the per-cpu interrupt state and stimer state.
+	 * Then connect to the host.
+	 */
+	cpus_read_lock();
+	for_each_online_cpu(cpu) {
+		struct work_struct *work = per_cpu_ptr(works, cpu);
+
+		INIT_WORK(work, vmbus_percpu_work);
+		schedule_work_on(cpu, work);
+	}
+
+	for_each_online_cpu(cpu)
+		flush_work(per_cpu_ptr(works, cpu));
+
+	/* Register the callbacks for possible CPU online/offline'ing */
+	ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
+						   hv_synic_init, hv_synic_cleanup);
+	cpus_read_unlock();
+	free_percpu(works);
+	if (ret < 0)
+		goto err_alloc;
+	hyperv_cpuhp_online = ret;
+
+	ret = vmbus_connect();
+	if (ret)
+		goto err_connect;
+	return 0;
+
+err_connect:
+	cpuhp_remove_state(hyperv_cpuhp_online);
+	return -ENODEV;
+err_alloc:
+	hv_synic_free();
+	return -ENOMEM;
+}
+
+/*
+ * vmbus_bus_init -Main vmbus driver initialization routine.
+ *
+ * Here, we
+ *	- initialize the vmbus driver context
+ *	- invoke the vmbus hv main init routine
+ *	- retrieve the channel offers
+ */
+static int vmbus_bus_init(void)
+{
+	int ret;
+
+	ret = hv_init();
+	if (ret != 0) {
+		pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
+		return ret;
+	}
+
+	ret = bus_register(&hv_bus);
+	if (ret)
+		return ret;
+
+	/*
+	 * VMbus interrupts are best modeled as per-cpu interrupts. If
+	 * on an architecture with support for per-cpu IRQs (e.g. ARM64),
+	 * allocate a per-cpu IRQ using standard Linux kernel functionality.
+	 * If not on such an architecture (e.g., x86/x64), then rely on
+	 * code in the arch-specific portion of the code tree to connect
+	 * the VMbus interrupt handler.
+	 */
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		ret = smpboot_register_percpu_thread(&vmbus_irq_threads);
+		if (ret)
+			goto err_kthread;
+	}
+
+	if (vmbus_irq == -1) {
+		hv_setup_vmbus_handler(vmbus_isr);
+	} else {
+		ret = request_percpu_irq(vmbus_irq, vmbus_percpu_isr,
+				"Hyper-V VMbus", &vmbus_evt);
+		if (ret) {
+			pr_err("Can't request Hyper-V VMbus IRQ %d, Err %d",
+					vmbus_irq, ret);
+			goto err_setup;
+		}
+	}
+
+	/*
+	 * Cache the value as getting it involves a VM exit on x86(_64), and
+	 * doing that on each VP while initializing SynIC's wastes time.
+	 */
+	is_confidential = ms_hyperv.confidential_vmbus_available;
+	if (is_confidential)
+		pr_info("Establishing connection to the confidential VMBus\n");
+	hv_para_set_sint_proxy(!is_confidential);
+	ret = vmbus_alloc_synic_and_connect();
+	if (ret)
+		goto err_connect;
+
+	/*
+	 * Always register the vmbus unload panic notifier because we
+	 * need to shut the VMbus channel connection on panic.
+	 */
+	atomic_notifier_chain_register(&panic_notifier_list,
+			       &hyperv_panic_vmbus_unload_block);
+
+	vmbus_request_offers();
+
+	return 0;
+
+err_connect:
+	if (vmbus_irq == -1)
+		hv_remove_vmbus_handler();
+	else
+		free_percpu_irq(vmbus_irq, &vmbus_evt);
+err_setup:
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		smpboot_unregister_percpu_thread(&vmbus_irq_threads);
+err_kthread:
+	bus_unregister(&hv_bus);
+	return ret;
+}
+
+/**
+ * __vmbus_driver_register() - Register a vmbus's driver
+ * @hv_driver: Pointer to driver structure you want to register
+ * @owner: owner module of the drv
+ * @mod_name: module name string
+ *
+ * Registers the given driver with Linux through the 'driver_register()' call
+ * and sets up the hyper-v vmbus handling for this driver.
+ * It will return the state of the 'driver_register()' call.
+ *
+ */
+int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)
+{
+	int ret;
+
+	if (!hv_vmbus_exists())
+		return -ENODEV;
+
+	pr_info("registering driver %s\n", hv_driver->name);
+
+	hv_driver->driver.name = hv_driver->name;
+	hv_driver->driver.owner = owner;
+	hv_driver->driver.mod_name = mod_name;
+	hv_driver->driver.bus = &hv_bus;
+
+	spin_lock_init(&hv_driver->dynids.lock);
+	INIT_LIST_HEAD(&hv_driver->dynids.list);
+
+	ret = driver_register(&hv_driver->driver);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__vmbus_driver_register);
+
+/**
+ * vmbus_driver_unregister() - Unregister a vmbus's driver
+ * @hv_driver: Pointer to driver structure you want to
+ *             un-register
+ *
+ * Un-register the given driver that was previous registered with a call to
+ * vmbus_driver_register()
+ */
+void vmbus_driver_unregister(struct hv_driver *hv_driver)
+{
+	if (hv_vmbus_exists()) {
+		pr_info("unregistering driver %s\n", hv_driver->name);
+		driver_unregister(&hv_driver->driver);
+		vmbus_free_dynids(hv_driver);
+	}
+}
+EXPORT_SYMBOL_GPL(vmbus_driver_unregister);
+
+
+/*
+ * Called when last reference to channel is gone.
+ */
+static void vmbus_chan_release(struct kobject *kobj)
+{
+	struct vmbus_channel *channel
+		= container_of(kobj, struct vmbus_channel, kobj);
+
+	kfree_rcu(channel, rcu);
+}
+
+struct vmbus_chan_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct vmbus_channel *chan, char *buf);
+	ssize_t (*store)(struct vmbus_channel *chan,
+			 const char *buf, size_t count);
+};
+#define VMBUS_CHAN_ATTR(_name, _mode, _show, _store) \
+	struct vmbus_chan_attribute chan_attr_##_name \
+		= __ATTR(_name, _mode, _show, _store)
+#define VMBUS_CHAN_ATTR_RW(_name) \
+	struct vmbus_chan_attribute chan_attr_##_name = __ATTR_RW(_name)
+#define VMBUS_CHAN_ATTR_RO(_name) \
+	struct vmbus_chan_attribute chan_attr_##_name = __ATTR_RO(_name)
+#define VMBUS_CHAN_ATTR_WO(_name) \
+	struct vmbus_chan_attribute chan_attr_##_name = __ATTR_WO(_name)
+
+static ssize_t vmbus_chan_attr_show(struct kobject *kobj,
+				    struct attribute *attr, char *buf)
+{
+	const struct vmbus_chan_attribute *attribute
+		= container_of(attr, struct vmbus_chan_attribute, attr);
+	struct vmbus_channel *chan
+		= container_of(kobj, struct vmbus_channel, kobj);
+
+	if (!attribute->show)
+		return -EIO;
+
+	return attribute->show(chan, buf);
+}
+
+static ssize_t vmbus_chan_attr_store(struct kobject *kobj,
+				     struct attribute *attr, const char *buf,
+				     size_t count)
+{
+	const struct vmbus_chan_attribute *attribute
+		= container_of(attr, struct vmbus_chan_attribute, attr);
+	struct vmbus_channel *chan
+		= container_of(kobj, struct vmbus_channel, kobj);
+
+	if (!attribute->store)
+		return -EIO;
+
+	return attribute->store(chan, buf, count);
+}
+
+static const struct sysfs_ops vmbus_chan_sysfs_ops = {
+	.show = vmbus_chan_attr_show,
+	.store = vmbus_chan_attr_store,
+};
+
+static ssize_t out_mask_show(struct vmbus_channel *channel, char *buf)
+{
+	struct hv_ring_buffer_info *rbi = &channel->outbound;
+	ssize_t ret;
+
+	mutex_lock(&rbi->ring_buffer_mutex);
+	if (!rbi->ring_buffer) {
+		mutex_unlock(&rbi->ring_buffer_mutex);
+		return -EINVAL;
+	}
+
+	ret = sprintf(buf, "%u\n", rbi->ring_buffer->interrupt_mask);
+	mutex_unlock(&rbi->ring_buffer_mutex);
+	return ret;
+}
+static VMBUS_CHAN_ATTR_RO(out_mask);
+
+static ssize_t in_mask_show(struct vmbus_channel *channel, char *buf)
+{
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+	ssize_t ret;
+
+	mutex_lock(&rbi->ring_buffer_mutex);
+	if (!rbi->ring_buffer) {
+		mutex_unlock(&rbi->ring_buffer_mutex);
+		return -EINVAL;
+	}
+
+	ret = sprintf(buf, "%u\n", rbi->ring_buffer->interrupt_mask);
+	mutex_unlock(&rbi->ring_buffer_mutex);
+	return ret;
+}
+static VMBUS_CHAN_ATTR_RO(in_mask);
+
+static ssize_t read_avail_show(struct vmbus_channel *channel, char *buf)
+{
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+	ssize_t ret;
+
+	mutex_lock(&rbi->ring_buffer_mutex);
+	if (!rbi->ring_buffer) {
+		mutex_unlock(&rbi->ring_buffer_mutex);
+		return -EINVAL;
+	}
+
+	ret = sprintf(buf, "%u\n", hv_get_bytes_to_read(rbi));
+	mutex_unlock(&rbi->ring_buffer_mutex);
+	return ret;
+}
+static VMBUS_CHAN_ATTR_RO(read_avail);
+
+static ssize_t write_avail_show(struct vmbus_channel *channel, char *buf)
+{
+	struct hv_ring_buffer_info *rbi = &channel->outbound;
+	ssize_t ret;
+
+	mutex_lock(&rbi->ring_buffer_mutex);
+	if (!rbi->ring_buffer) {
+		mutex_unlock(&rbi->ring_buffer_mutex);
+		return -EINVAL;
+	}
+
+	ret = sprintf(buf, "%u\n", hv_get_bytes_to_write(rbi));
+	mutex_unlock(&rbi->ring_buffer_mutex);
+	return ret;
+}
+static VMBUS_CHAN_ATTR_RO(write_avail);
+
+static ssize_t target_cpu_show(struct vmbus_channel *channel, char *buf)
+{
+	return sprintf(buf, "%u\n", channel->target_cpu);
+}
+
+int vmbus_channel_set_cpu(struct vmbus_channel *channel, u32 target_cpu)
+{
+	u32 origin_cpu;
+	int ret = 0;
+
+	lockdep_assert_cpus_held();
+	lockdep_assert_held(&vmbus_connection.channel_mutex);
+
+	if (vmbus_proto_version < VERSION_WIN10_V4_1)
+		return -EIO;
+
+	/* Validate target_cpu for the cpumask_test_cpu() operation below. */
+	if (target_cpu >= nr_cpumask_bits)
+		return -EINVAL;
+
+	if (!cpumask_test_cpu(target_cpu, housekeeping_cpumask(HK_TYPE_MANAGED_IRQ)))
+		return -EINVAL;
+
+	if (!cpu_online(target_cpu))
+		return -EINVAL;
+
+	/*
+	 * Synchronizes vmbus_channel_set_cpu() and channel closure:
+	 *
+	 * { Initially: state = CHANNEL_OPENED }
+	 *
+	 * CPU1				CPU2
+	 *
+	 * [vmbus_channel_set_cpu()]	[vmbus_disconnect_ring()]
+	 *
+	 * LOCK channel_mutex		LOCK channel_mutex
+	 * LOAD r1 = state		LOAD r2 = state
+	 * IF (r1 == CHANNEL_OPENED)	IF (r2 == CHANNEL_OPENED)
+	 *   SEND MODIFYCHANNEL		  STORE state = CHANNEL_OPEN
+	 *   [...]			  SEND CLOSECHANNEL
+	 * UNLOCK channel_mutex		UNLOCK channel_mutex
+	 *
+	 * Forbids: r1 == r2 == CHANNEL_OPENED (i.e., CPU1's LOCK precedes
+	 * 		CPU2's LOCK) && CPU2's SEND precedes CPU1's SEND
+	 *
+	 * Note.  The host processes the channel messages "sequentially", in
+	 * the order in which they are received on a per-partition basis.
+	 */
+
+	/*
+	 * Hyper-V will ignore MODIFYCHANNEL messages for "non-open" channels;
+	 * avoid sending the message and fail here for such channels.
+	 */
+	if (channel->state != CHANNEL_OPENED_STATE) {
+		ret = -EIO;
+		goto end;
+	}
+
+	origin_cpu = channel->target_cpu;
+	if (target_cpu == origin_cpu)
+		goto end;
+
+	if (vmbus_send_modifychannel(channel,
+				     hv_cpu_number_to_vp_number(target_cpu))) {
+		ret = -EIO;
+		goto end;
+	}
+
+	/*
+	 * For version before VERSION_WIN10_V5_3, the following warning holds:
+	 *
+	 * Warning.  At this point, there is *no* guarantee that the host will
+	 * have successfully processed the vmbus_send_modifychannel() request.
+	 * See the header comment of vmbus_send_modifychannel() for more info.
+	 *
+	 * Lags in the processing of the above vmbus_send_modifychannel() can
+	 * result in missed interrupts if the "old" target CPU is taken offline
+	 * before Hyper-V starts sending interrupts to the "new" target CPU.
+	 * But apart from this offlining scenario, the code tolerates such
+	 * lags.  It will function correctly even if a channel interrupt comes
+	 * in on a CPU that is different from the channel target_cpu value.
+	 */
+
+	channel->target_cpu = target_cpu;
+
+	/* See init_vp_index(). */
+	if (hv_is_perf_channel(channel))
+		hv_update_allocated_cpus(origin_cpu, target_cpu);
+
+	/* Currently set only for storvsc channels. */
+	if (channel->change_target_cpu_callback) {
+		(*channel->change_target_cpu_callback)(channel,
+				origin_cpu, target_cpu);
+	}
+
+end:
+	return ret;
+}
+
+static ssize_t target_cpu_store(struct vmbus_channel *channel,
+				const char *buf, size_t count)
+{
+	u32 target_cpu;
+	ssize_t ret;
+
+	if (sscanf(buf, "%u", &target_cpu) != 1)
+		return -EIO;
+
+	cpus_read_lock();
+	mutex_lock(&vmbus_connection.channel_mutex);
+	ret = vmbus_channel_set_cpu(channel, target_cpu);
+	mutex_unlock(&vmbus_connection.channel_mutex);
+	cpus_read_unlock();
+
+	return ret ?: count;
+}
+static VMBUS_CHAN_ATTR(cpu, 0644, target_cpu_show, target_cpu_store);
+
+static ssize_t channel_pending_show(struct vmbus_channel *channel,
+				    char *buf)
+{
+	return sprintf(buf, "%d\n",
+		       channel_pending(channel,
+				       vmbus_connection.monitor_pages[1]));
+}
+static VMBUS_CHAN_ATTR(pending, 0444, channel_pending_show, NULL);
+
+static ssize_t channel_latency_show(struct vmbus_channel *channel,
+				    char *buf)
+{
+	return sprintf(buf, "%d\n",
+		       channel_latency(channel,
+				       vmbus_connection.monitor_pages[1]));
+}
+static VMBUS_CHAN_ATTR(latency, 0444, channel_latency_show, NULL);
+
+static ssize_t channel_interrupts_show(struct vmbus_channel *channel, char *buf)
+{
+	return sprintf(buf, "%llu\n", channel->interrupts);
+}
+static VMBUS_CHAN_ATTR(interrupts, 0444, channel_interrupts_show, NULL);
+
+static ssize_t channel_events_show(struct vmbus_channel *channel, char *buf)
+{
+	return sprintf(buf, "%llu\n", channel->sig_events);
+}
+static VMBUS_CHAN_ATTR(events, 0444, channel_events_show, NULL);
+
+static ssize_t channel_intr_in_full_show(struct vmbus_channel *channel,
+					 char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->intr_in_full);
+}
+static VMBUS_CHAN_ATTR(intr_in_full, 0444, channel_intr_in_full_show, NULL);
+
+static ssize_t channel_intr_out_empty_show(struct vmbus_channel *channel,
+					   char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->intr_out_empty);
+}
+static VMBUS_CHAN_ATTR(intr_out_empty, 0444, channel_intr_out_empty_show, NULL);
+
+static ssize_t channel_out_full_first_show(struct vmbus_channel *channel,
+					   char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->out_full_first);
+}
+static VMBUS_CHAN_ATTR(out_full_first, 0444, channel_out_full_first_show, NULL);
+
+static ssize_t channel_out_full_total_show(struct vmbus_channel *channel,
+					   char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->out_full_total);
+}
+static VMBUS_CHAN_ATTR(out_full_total, 0444, channel_out_full_total_show, NULL);
+
+static ssize_t subchannel_monitor_id_show(struct vmbus_channel *channel,
+					  char *buf)
+{
+	return sprintf(buf, "%u\n", channel->offermsg.monitorid);
+}
+static VMBUS_CHAN_ATTR(monitor_id, 0444, subchannel_monitor_id_show, NULL);
+
+static ssize_t subchannel_id_show(struct vmbus_channel *channel,
+				  char *buf)
+{
+	return sprintf(buf, "%u\n",
+		       channel->offermsg.offer.sub_channel_index);
+}
+static VMBUS_CHAN_ATTR_RO(subchannel_id);
+
+static int hv_mmap_ring_buffer_wrapper(struct file *filp, struct kobject *kobj,
+				       const struct bin_attribute *attr,
+				       struct vm_area_struct *vma)
+{
+	struct vmbus_channel *channel = container_of(kobj, struct vmbus_channel, kobj);
+	struct vm_area_desc desc;
+	int err;
+
+	/*
+	 * hv_(create|remove)_ring_sysfs implementation ensures that
+	 * mmap_prepare_ring_buffer is not NULL.
+	 */
+	compat_set_desc_from_vma(&desc, filp, vma);
+	err = channel->mmap_prepare_ring_buffer(channel, &desc);
+	if (err)
+		return err;
+
+	return __compat_vma_mmap(&desc, vma);
+}
+
+static struct bin_attribute chan_attr_ring_buffer = {
+	.attr = {
+		.name = "ring",
+		.mode = 0600,
+	},
+	.mmap = hv_mmap_ring_buffer_wrapper,
+};
+static struct attribute *vmbus_chan_attrs[] = {
+	&chan_attr_out_mask.attr,
+	&chan_attr_in_mask.attr,
+	&chan_attr_read_avail.attr,
+	&chan_attr_write_avail.attr,
+	&chan_attr_cpu.attr,
+	&chan_attr_pending.attr,
+	&chan_attr_latency.attr,
+	&chan_attr_interrupts.attr,
+	&chan_attr_events.attr,
+	&chan_attr_intr_in_full.attr,
+	&chan_attr_intr_out_empty.attr,
+	&chan_attr_out_full_first.attr,
+	&chan_attr_out_full_total.attr,
+	&chan_attr_monitor_id.attr,
+	&chan_attr_subchannel_id.attr,
+	NULL
+};
+
+static const struct bin_attribute *vmbus_chan_bin_attrs[] = {
+	&chan_attr_ring_buffer,
+	NULL
+};
+
+/*
+ * Channel-level attribute_group callback function. Returns the permission for
+ * each attribute, and returns 0 if an attribute is not visible.
+ */
+static umode_t vmbus_chan_attr_is_visible(struct kobject *kobj,
+					  struct attribute *attr, int idx)
+{
+	const struct vmbus_channel *channel =
+		container_of(kobj, struct vmbus_channel, kobj);
+
+	/* Hide the monitor attributes if the monitor mechanism is not used. */
+	if (!channel->offermsg.monitor_allocated &&
+	    (attr == &chan_attr_pending.attr ||
+	     attr == &chan_attr_latency.attr ||
+	     attr == &chan_attr_monitor_id.attr))
+		return 0;
+
+	return attr->mode;
+}
+
+static umode_t vmbus_chan_bin_attr_is_visible(struct kobject *kobj,
+					      const struct bin_attribute *attr, int idx)
+{
+	const struct vmbus_channel *channel =
+		container_of(kobj, struct vmbus_channel, kobj);
+
+	/* Hide ring attribute if channel's ring_sysfs_visible is set to false */
+	if (attr ==  &chan_attr_ring_buffer && !channel->ring_sysfs_visible)
+		return 0;
+
+	return attr->attr.mode;
+}
+
+static size_t vmbus_chan_bin_size(struct kobject *kobj,
+				  const struct bin_attribute *bin_attr, int a)
+{
+	const struct vmbus_channel *channel =
+		container_of(kobj, struct vmbus_channel, kobj);
+
+	return channel->ringbuffer_pagecount << PAGE_SHIFT;
+}
+
+static const struct attribute_group vmbus_chan_group = {
+	.attrs = vmbus_chan_attrs,
+	.bin_attrs = vmbus_chan_bin_attrs,
+	.is_visible = vmbus_chan_attr_is_visible,
+	.is_bin_visible = vmbus_chan_bin_attr_is_visible,
+	.bin_size = vmbus_chan_bin_size,
+};
+
+static const struct kobj_type vmbus_chan_ktype = {
+	.sysfs_ops = &vmbus_chan_sysfs_ops,
+	.release = vmbus_chan_release,
+};
+
+/**
+ * hv_create_ring_sysfs() - create "ring" sysfs entry corresponding to ring buffers for a channel.
+ * @channel: Pointer to vmbus_channel structure
+ * @hv_mmap_prepare_ring_buffer: function pointer for initializing the function to be called on mmap
+ *                       channel's "ring" sysfs node, which is for the ring buffer of that channel.
+ *                       Function pointer is of below type:
+ *                       int (*hv_mmap_prepare_ring_buffer)(struct vmbus_channel *channel,
+ *                                                          struct vm_area_desc *desc))
+ *                       This has a pointer to the channel and a pointer to vm_area_desc,
+ *                       used for mmap_prepare, as arguments.
+ *
+ * Sysfs node for ring buffer of a channel is created along with other fields, however its
+ * visibility is disabled by default. Sysfs creation needs to be controlled when the use-case
+ * is running.
+ * For example, HV_NIC device is used either by uio_hv_generic or hv_netvsc at any given point of
+ * time, and "ring" sysfs is needed only when uio_hv_generic is bound to that device. To avoid
+ * exposing the ring buffer by default, this function is responsible to enable visibility of
+ * ring for userspace to use.
+ * Note: Race conditions can happen with userspace and it is not encouraged to create new
+ * use-cases for this. This was added to maintain backward compatibility, while solving
+ * one of the race conditions in uio_hv_generic while creating sysfs. See comments with
+ * vmbus_add_dynid() and vmbus_device_register().
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int hv_create_ring_sysfs(struct vmbus_channel *channel,
+			 int (*hv_mmap_prepare_ring_buffer)(struct vmbus_channel *channel,
+							    struct vm_area_desc *desc))
+{
+	struct kobject *kobj = &channel->kobj;
+
+	channel->mmap_prepare_ring_buffer = hv_mmap_prepare_ring_buffer;
+	channel->ring_sysfs_visible = true;
+
+	return sysfs_update_group(kobj, &vmbus_chan_group);
+}
+EXPORT_SYMBOL_GPL(hv_create_ring_sysfs);
+
+/**
+ * hv_remove_ring_sysfs() - remove ring sysfs entry corresponding to ring buffers for a channel.
+ * @channel: Pointer to vmbus_channel structure
+ *
+ * Hide "ring" sysfs for a channel by changing its is_visible attribute and updating sysfs group.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int hv_remove_ring_sysfs(struct vmbus_channel *channel)
+{
+	struct kobject *kobj = &channel->kobj;
+	int ret;
+
+	channel->ring_sysfs_visible = false;
+	ret = sysfs_update_group(kobj, &vmbus_chan_group);
+	channel->mmap_prepare_ring_buffer = NULL;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hv_remove_ring_sysfs);
+
+/*
+ * vmbus_add_channel_kobj - setup a sub-directory under device/channels
+ */
+int vmbus_add_channel_kobj(struct hv_device *dev, struct vmbus_channel *channel)
+{
+	const struct device *device = &dev->device;
+	struct kobject *kobj = &channel->kobj;
+	u32 relid = channel->offermsg.child_relid;
+	int ret;
+
+	kobj->kset = dev->channels_kset;
+	ret = kobject_init_and_add(kobj, &vmbus_chan_ktype, NULL,
+				   "%u", relid);
+	if (ret) {
+		kobject_put(kobj);
+		return ret;
+	}
+
+	ret = sysfs_create_group(kobj, &vmbus_chan_group);
+
+	if (ret) {
+		/*
+		 * The calling functions' error handling paths will cleanup the
+		 * empty channel directory.
+		 */
+		kobject_put(kobj);
+		dev_err(device, "Unable to set up channel sysfs files\n");
+		return ret;
+	}
+
+	kobject_uevent(kobj, KOBJ_ADD);
+
+	return 0;
+}
+
+/*
+ * vmbus_remove_channel_attr_group - remove the channel's attribute group
+ */
+void vmbus_remove_channel_attr_group(struct vmbus_channel *channel)
+{
+	sysfs_remove_group(&channel->kobj, &vmbus_chan_group);
+}
+
+/*
+ * vmbus_device_create - Creates and registers a new child device
+ * on the vmbus.
+ */
+struct hv_device *vmbus_device_create(const guid_t *type,
+				      const guid_t *instance,
+				      struct vmbus_channel *channel)
+{
+	struct hv_device *child_device_obj;
+
+	child_device_obj = kzalloc_obj(struct hv_device);
+	if (!child_device_obj) {
+		pr_err("Unable to allocate device object for child device\n");
+		return NULL;
+	}
+
+	child_device_obj->channel = channel;
+	guid_copy(&child_device_obj->dev_type, type);
+	guid_copy(&child_device_obj->dev_instance, instance);
+	child_device_obj->vendor_id = PCI_VENDOR_ID_MICROSOFT;
+
+	return child_device_obj;
+}
+
+/*
+ * vmbus_device_register - Register the child device
+ */
+int vmbus_device_register(struct hv_device *child_device_obj)
+{
+	struct kobject *kobj = &child_device_obj->device.kobj;
+	int ret;
+
+	dev_set_name(&child_device_obj->device, "%pUl",
+		     &child_device_obj->channel->offermsg.offer.if_instance);
+
+	child_device_obj->device.bus = &hv_bus;
+	child_device_obj->device.parent = vmbus_root_device;
+	child_device_obj->device.release = vmbus_device_release;
+
+	child_device_obj->device.dma_parms = &child_device_obj->dma_parms;
+	child_device_obj->device.dma_mask = &child_device_obj->dma_mask;
+	dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64));
+	dma_set_coherent_mask(&child_device_obj->device, DMA_BIT_MASK(64));
+
+	/*
+	 * Register with the LDM. This will kick off the driver/device
+	 * binding...which will eventually call vmbus_match() and vmbus_probe()
+	 */
+	ret = device_register(&child_device_obj->device);
+	if (ret) {
+		pr_err("Unable to register child device\n");
+		put_device(&child_device_obj->device);
+		return ret;
+	}
+
+	/*
+	 * If device_register() found a driver to assign to the device, the
+	 * driver's probe function has already run at this point. If that
+	 * probe function accesses or operates on the "channels" subdirectory
+	 * in sysfs, those operations will have failed because the "channels"
+	 * subdirectory doesn't exist until the code below runs. Or if the
+	 * probe function creates a /dev entry, a user space program could
+	 * find and open the /dev entry, and then create a race by accessing
+	 * the "channels" subdirectory while the creation steps are in progress
+	 * here. The race can't result in a kernel failure, but the user space
+	 * program may get an error in accessing "channels" or its
+	 * subdirectories. See also comments with vmbus_add_dynid() about a
+	 * related race condition.
+	 */
+	child_device_obj->channels_kset = kset_create_and_add("channels",
+							      NULL, kobj);
+	if (!child_device_obj->channels_kset) {
+		ret = -ENOMEM;
+		goto err_dev_unregister;
+	}
+
+	ret = vmbus_add_channel_kobj(child_device_obj,
+				     child_device_obj->channel);
+	if (ret) {
+		pr_err("Unable to register primary channel\n");
+		goto err_kset_unregister;
+	}
+	hv_debug_add_dev_dir(child_device_obj);
+
+	return 0;
+
+err_kset_unregister:
+	kset_unregister(child_device_obj->channels_kset);
+
+err_dev_unregister:
+	device_unregister(&child_device_obj->device);
+	return ret;
+}
+
+/*
+ * vmbus_device_unregister - Remove the specified child device
+ * from the vmbus.
+ */
+void vmbus_device_unregister(struct hv_device *device_obj)
+{
+	pr_debug("child device %s unregistered\n",
+		dev_name(&device_obj->device));
+
+	kset_unregister(device_obj->channels_kset);
+
+	/*
+	 * Kick off the process of unregistering the device.
+	 * This will call vmbus_remove() and eventually vmbus_device_release()
+	 */
+	device_unregister(&device_obj->device);
+}
+EXPORT_SYMBOL_GPL(vmbus_device_unregister);
+
+#ifdef CONFIG_ACPI
+/*
+ * VMBUS is an acpi enumerated device. Get the information we
+ * need from DSDT.
+ */
+static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
+{
+	resource_size_t start = 0;
+	resource_size_t end = 0;
+	struct resource *new_res;
+	struct resource **old_res = &hyperv_mmio;
+	struct resource **prev_res = NULL;
+	struct resource r;
+
+	switch (res->type) {
+
+	/*
+	 * "Address" descriptors are for bus windows. Ignore
+	 * "memory" descriptors, which are for registers on
+	 * devices.
+	 */
+	case ACPI_RESOURCE_TYPE_ADDRESS32:
+		start = res->data.address32.address.minimum;
+		end = res->data.address32.address.maximum;
+		break;
+
+	case ACPI_RESOURCE_TYPE_ADDRESS64:
+		start = res->data.address64.address.minimum;
+		end = res->data.address64.address.maximum;
+		break;
+
+	/*
+	 * The IRQ information is needed only on ARM64, which Hyper-V
+	 * sets up in the extended format. IRQ information is present
+	 * on x86/x64 in the non-extended format but it is not used by
+	 * Linux. So don't bother checking for the non-extended format.
+	 */
+	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
+		if (!acpi_dev_resource_interrupt(res, 0, &r)) {
+			pr_err("Unable to parse Hyper-V ACPI interrupt\n");
+			return AE_ERROR;
+		}
+		/* ARM64 INTID for VMbus */
+		vmbus_interrupt = res->data.extended_irq.interrupts[0];
+		/* Linux IRQ number */
+		vmbus_irq = r.start;
+		return AE_OK;
+
+	default:
+		/* Unused resource type */
+		return AE_OK;
+
+	}
+	/*
+	 * Ignore ranges that are below 1MB, as they're not
+	 * necessary or useful here.
+	 */
+	if (end < 0x100000)
+		return AE_OK;
+
+	new_res = kzalloc_obj(*new_res, GFP_ATOMIC);
+	if (!new_res)
+		return AE_NO_MEMORY;
+
+	/* If this range overlaps the virtual TPM, truncate it. */
+	if (end >= VTPM_BASE_ADDRESS && start < VTPM_BASE_ADDRESS)
+		end = VTPM_BASE_ADDRESS - 1;
+
+	new_res->name = "hyperv mmio";
+	new_res->flags = IORESOURCE_MEM;
+	new_res->start = start;
+	new_res->end = end;
+
+	/*
+	 * If two ranges are adjacent, merge them.
+	 */
+	do {
+		if (!*old_res) {
+			*old_res = new_res;
+			break;
+		}
+
+		if (((*old_res)->end + 1) == new_res->start) {
+			(*old_res)->end = new_res->end;
+			kfree(new_res);
+			break;
+		}
+
+		if ((*old_res)->start == new_res->end + 1) {
+			(*old_res)->start = new_res->start;
+			kfree(new_res);
+			break;
+		}
+
+		if ((*old_res)->start > new_res->end) {
+			new_res->sibling = *old_res;
+			if (prev_res)
+				(*prev_res)->sibling = new_res;
+			*old_res = new_res;
+			break;
+		}
+
+		prev_res = old_res;
+		old_res = &(*old_res)->sibling;
+
+	} while (1);
+
+	return AE_OK;
+}
+#endif
+
+static void vmbus_mmio_remove(void)
+{
+	struct resource *cur_res;
+	struct resource *next_res;
+
+	if (hyperv_mmio) {
+		if (fb_mmio) {
+			__release_region(hyperv_mmio, fb_mmio->start,
+					 resource_size(fb_mmio));
+			fb_mmio = NULL;
+		}
+
+		for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
+			next_res = cur_res->sibling;
+			kfree(cur_res);
+		}
+	}
+}
+
+static void __maybe_unused vmbus_reserve_fb(void)
+{
+	resource_size_t start = 0, size;
+	resource_size_t low_mmio_base;
+	struct pci_dev *pdev;
+
+	if (efi_enabled(EFI_BOOT)) {
+		/* Gen2 VM: get FB base from EFI framebuffer */
+		if (IS_ENABLED(CONFIG_SYSFB)) {
+			start = sysfb_primary_display.screen.lfb_base;
+			size = max_t(__u32, sysfb_primary_display.screen.lfb_size, 0x800000);
+
+			low_mmio_base = hyperv_mmio->start;
+			if (!low_mmio_base || upper_32_bits(low_mmio_base) ||
+			    (start && start < low_mmio_base)) {
+				pr_warn("Unexpected low mmio base %pa\n", &low_mmio_base);
+			} else {
+				/*
+				 * If the kdump/kexec or CVM kernel's lfb_base
+				 * is 0, fall back to the low mmio base.
+				 */
+				if (!start)
+					start = low_mmio_base;
+				/*
+				 * Reserve half of the space below 4GB for high
+				 * resolutions, but cap the reservation to 128MB.
+				 */
+				size = min((SZ_4G - start) / 2, SZ_128M);
+			}
+		}
+	} else {
+		/* Gen1 VM: get FB base from PCI */
+		pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
+				      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
+		if (!pdev)
+			return;
+
+		if (pdev->resource[0].flags & IORESOURCE_MEM) {
+			start = pci_resource_start(pdev, 0);
+			size = pci_resource_len(pdev, 0);
+		}
+
+		/*
+		 * Release the PCI device so hyperv_drm driver can grab it
+		 * later.
+		 */
+		pci_dev_put(pdev);
+	}
+
+	if (!start) {
+		pr_warn("Unexpected framebuffer mmio base of zero\n");
+		return;
+	}
+
+	/*
+	 * Make a claim for the frame buffer in the resource tree under the
+	 * first node, which will be the one below 4GB.  The length seems to
+	 * be underreported, particularly in a Generation 1 VM.  So start out
+	 * reserving a larger area and make it smaller until it succeeds.
+	 */
+	for (; !fb_mmio && (size >= 0x100000); size >>= 1)
+		fb_mmio = __request_region(hyperv_mmio, start, size, fb_mmio_name, 0);
+
+	pr_info("hv_mmio=%pR,%pR fb=%pR\n", hyperv_mmio, hyperv_mmio->sibling, fb_mmio);
+}
+
+/**
+ * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
+ * @new:		If successful, supplied a pointer to the
+ *			allocated MMIO space.
+ * @device_obj:		Identifies the caller
+ * @min:		Minimum guest physical address of the
+ *			allocation
+ * @max:		Maximum guest physical address
+ * @size:		Size of the range to be allocated
+ * @align:		Alignment of the range to be allocated
+ * @fb_overlap_ok:	Whether this allocation can be allowed
+ *			to overlap the video frame buffer.
+ *
+ * This function walks the resources granted to VMBus by the
+ * _CRS object in the ACPI namespace underneath the parent
+ * "bridge" whether that's a root PCI bus in the Generation 1
+ * case or a Module Device in the Generation 2 case.  It then
+ * attempts to allocate from the global MMIO pool in a way that
+ * matches the constraints supplied in these parameters and by
+ * that _CRS.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
+			resource_size_t min, resource_size_t max,
+			resource_size_t size, resource_size_t align,
+			bool fb_overlap_ok)
+{
+	struct resource *iter, *shadow;
+	resource_size_t range_min, range_max, start, end;
+	const char *dev_n = dev_name(&device_obj->device);
+	int retval;
+
+	retval = -ENXIO;
+	mutex_lock(&hyperv_mmio_lock);
+
+	/*
+	 * If overlaps with frame buffers are allowed, then first attempt to
+	 * make the allocation from within the reserved region.  Because it
+	 * is already reserved, no shadow allocation is necessary.
+	 */
+	if (fb_overlap_ok && fb_mmio && !(min > fb_mmio->end) &&
+	    !(max < fb_mmio->start)) {
+
+		range_min = fb_mmio->start;
+		range_max = fb_mmio->end;
+		start = (range_min + align - 1) & ~(align - 1);
+		for (; start + size - 1 <= range_max; start += align) {
+			*new = request_mem_region_exclusive(start, size, dev_n);
+			if (*new) {
+				retval = 0;
+				goto exit;
+			}
+		}
+	}
+
+	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
+		if ((iter->start >= max) || (iter->end <= min))
+			continue;
+
+		range_min = iter->start;
+		range_max = iter->end;
+		start = (range_min + align - 1) & ~(align - 1);
+		for (; start + size - 1 <= range_max; start += align) {
+			end = start + size - 1;
+
+			/* Skip the whole fb_mmio region if not fb_overlap_ok */
+			if (!fb_overlap_ok && fb_mmio &&
+			    (((start >= fb_mmio->start) && (start <= fb_mmio->end)) ||
+			     ((end >= fb_mmio->start) && (end <= fb_mmio->end))))
+				continue;
+
+			shadow = __request_region(iter, start, size, NULL,
+						  IORESOURCE_BUSY);
+			if (!shadow)
+				continue;
+
+			*new = request_mem_region_exclusive(start, size, dev_n);
+			if (*new) {
+				shadow->name = (char *)*new;
+				retval = 0;
+				goto exit;
+			}
+
+			__release_region(iter, start, size);
+		}
+	}
+
+exit:
+	mutex_unlock(&hyperv_mmio_lock);
+	return retval;
+}
+EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);
+
+/**
+ * vmbus_free_mmio() - Free a memory-mapped I/O range.
+ * @start:		Base address of region to release.
+ * @size:		Size of the range to be allocated
+ *
+ * This function releases anything requested by
+ * vmbus_mmio_allocate().
+ */
+void vmbus_free_mmio(resource_size_t start, resource_size_t size)
+{
+	struct resource *iter;
+
+	mutex_lock(&hyperv_mmio_lock);
+
+	/*
+	 * If all bytes of the MMIO range to be released are within the
+	 * special case fb_mmio shadow region, skip releasing the shadow
+	 * region since no corresponding __request_region() was done
+	 * in vmbus_allocate_mmio().
+	 */
+	if (fb_mmio && start >= fb_mmio->start &&
+	    (start + size - 1 <= fb_mmio->end))
+		goto skip_shadow_release;
+
+	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
+		if ((iter->start >= start + size) || (iter->end <= start))
+			continue;
+
+		__release_region(iter, start, size);
+	}
+
+skip_shadow_release:
+	release_mem_region(start, size);
+	mutex_unlock(&hyperv_mmio_lock);
+
+}
+EXPORT_SYMBOL_GPL(vmbus_free_mmio);
+
+#ifdef CONFIG_ACPI
+static int vmbus_acpi_add(struct platform_device *pdev)
+{
+	acpi_status result;
+	int ret_val = -ENODEV;
+	struct acpi_device *ancestor;
+	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+
+	vmbus_root_device = &device->dev;
+
+	/*
+	 * Older versions of Hyper-V for ARM64 fail to include the _CCA
+	 * method on the top level VMbus device in the DSDT. But devices
+	 * are hardware coherent in all current Hyper-V use cases, so fix
+	 * up the ACPI device to behave as if _CCA is present and indicates
+	 * hardware coherence.
+	 */
+	ACPI_COMPANION_SET(&device->dev, device);
+	if (IS_ENABLED(CONFIG_ACPI_CCA_REQUIRED) &&
+	    device_get_dma_attr(&device->dev) == DEV_DMA_NOT_SUPPORTED) {
+		pr_info("No ACPI _CCA found; assuming coherent device I/O\n");
+		device->flags.cca_seen = true;
+		device->flags.coherent_dma = true;
+	}
+
+	result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+					vmbus_walk_resources, NULL);
+
+	if (ACPI_FAILURE(result))
+		goto acpi_walk_err;
+	/*
+	 * Some ancestor of the vmbus acpi device (Gen1 or Gen2
+	 * firmware) is the VMOD that has the mmio ranges. Get that.
+	 */
+	for (ancestor = acpi_dev_parent(device);
+	     ancestor && ancestor->handle != ACPI_ROOT_OBJECT;
+	     ancestor = acpi_dev_parent(ancestor)) {
+		result = acpi_walk_resources(ancestor->handle, METHOD_NAME__CRS,
+					     vmbus_walk_resources, NULL);
+
+		if (ACPI_FAILURE(result))
+			continue;
+		if (hyperv_mmio) {
+			vmbus_reserve_fb();
+			break;
+		}
+	}
+	ret_val = 0;
+
+acpi_walk_err:
+	if (ret_val)
+		vmbus_mmio_remove();
+	return ret_val;
+}
+#else
+static int vmbus_acpi_add(struct platform_device *pdev)
+{
+	return 0;
+}
+#endif
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+static int vmbus_set_irq(struct platform_device *pdev)
+{
+	struct irq_data *data;
+	int irq;
+	irq_hw_number_t hwirq;
+
+	irq = platform_get_irq(pdev, 0);
+	/* platform_get_irq() may not return 0. */
+	if (irq < 0)
+		return irq;
+
+	data = irq_get_irq_data(irq);
+	if (!data) {
+		pr_err("No interrupt data for VMBus virq %d\n", irq);
+		return -ENODEV;
+	}
+	hwirq = irqd_to_hwirq(data);
+
+	vmbus_irq = irq;
+	vmbus_interrupt = hwirq;
+	pr_debug("VMBus virq %d, hwirq %d\n", vmbus_irq, vmbus_interrupt);
+
+	return 0;
+}
+#endif
+
+static int vmbus_device_add(struct platform_device *pdev)
+{
+	struct resource **cur_res = &hyperv_mmio;
+	struct of_range range;
+	struct of_range_parser parser;
+	struct device_node *np = pdev->dev.of_node;
+	int ret;
+
+	vmbus_root_device = &pdev->dev;
+
+	ret = of_range_parser_init(&parser, np);
+	if (ret)
+		return ret;
+
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+	ret = vmbus_set_irq(pdev);
+	if (ret)
+		return ret;
+#endif
+	for_each_of_range(&parser, &range) {
+		struct resource *res;
+
+		res = kzalloc_obj(*res);
+		if (!res) {
+			vmbus_mmio_remove();
+			return -ENOMEM;
+		}
+
+		res->name = "hyperv mmio";
+		res->flags = range.flags;
+		res->start = range.cpu_addr;
+		res->end = range.cpu_addr + range.size;
+
+		*cur_res = res;
+		cur_res = &res->sibling;
+	}
+
+	return ret;
+}
+
+static int vmbus_platform_driver_probe(struct platform_device *pdev)
+{
+	if (acpi_disabled)
+		return vmbus_device_add(pdev);
+	else
+		return vmbus_acpi_add(pdev);
+}
+
+static void vmbus_platform_driver_remove(struct platform_device *pdev)
+{
+	vmbus_mmio_remove();
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int vmbus_bus_suspend(struct device *dev)
+{
+	struct hv_per_cpu_context *hv_cpu = per_cpu_ptr(
+			hv_context.cpu_context, VMBUS_CONNECT_CPU);
+	struct vmbus_channel *channel, *sc;
+
+	tasklet_disable(&hv_cpu->msg_dpc);
+	vmbus_connection.ignore_any_offer_msg = true;
+	/* The tasklet_enable() takes care of providing a memory barrier */
+	tasklet_enable(&hv_cpu->msg_dpc);
+
+	/* Drain all the workqueues as we are in suspend */
+	drain_workqueue(vmbus_connection.rescind_work_queue);
+	drain_workqueue(vmbus_connection.work_queue);
+	drain_workqueue(vmbus_connection.handle_primary_chan_wq);
+	drain_workqueue(vmbus_connection.handle_sub_chan_wq);
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (!is_hvsock_channel(channel))
+			continue;
+
+		vmbus_force_channel_rescinded(channel);
+	}
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	/*
+	 * Wait until all the sub-channels and hv_sock channels have been
+	 * cleaned up. Sub-channels should be destroyed upon suspend, otherwise
+	 * they would conflict with the new sub-channels that will be created
+	 * in the resume path. hv_sock channels should also be destroyed, but
+	 * a hv_sock channel of an established hv_sock connection can not be
+	 * really destroyed since it may still be referenced by the userspace
+	 * application, so we just force the hv_sock channel to be rescinded
+	 * by vmbus_force_channel_rescinded(), and the userspace application
+	 * will thoroughly destroy the channel after hibernation.
+	 *
+	 * Note: the counter nr_chan_close_on_suspend may never go above 0 if
+	 * the VM has no sub-channel and hv_sock channel, e.g. a 1-vCPU VM.
+	 */
+	if (atomic_read(&vmbus_connection.nr_chan_close_on_suspend) > 0)
+		wait_for_completion(&vmbus_connection.ready_for_suspend_event);
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		/*
+		 * Remove the channel from the array of channels and invalidate
+		 * the channel's relid.  Upon resume, vmbus_onoffer() will fix
+		 * up the relid (and other fields, if necessary) and add the
+		 * channel back to the array.
+		 */
+		vmbus_channel_unmap_relid(channel);
+		channel->offermsg.child_relid = INVALID_RELID;
+
+		if (is_hvsock_channel(channel)) {
+			if (!channel->rescind) {
+				pr_err("hv_sock channel not rescinded!\n");
+				WARN_ON_ONCE(1);
+			}
+			continue;
+		}
+
+		list_for_each_entry(sc, &channel->sc_list, sc_list) {
+			pr_err("Sub-channel not deleted!\n");
+			WARN_ON_ONCE(1);
+		}
+	}
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	vmbus_initiate_unload(false);
+
+	return 0;
+}
+
+static int vmbus_bus_resume(struct device *dev)
+{
+	struct vmbus_channel *channel;
+	struct vmbus_channel_msginfo *msginfo;
+	size_t msgsize;
+	int ret;
+
+	vmbus_connection.ignore_any_offer_msg = false;
+
+	/*
+	 * We only use the 'vmbus_proto_version', which was in use before
+	 * hibernation, to re-negotiate with the host.
+	 */
+	if (!vmbus_proto_version) {
+		pr_err("Invalid proto version = 0x%x\n", vmbus_proto_version);
+		return -EINVAL;
+	}
+
+	msgsize = sizeof(*msginfo) +
+		  sizeof(struct vmbus_channel_initiate_contact);
+
+	msginfo = kzalloc(msgsize, GFP_KERNEL);
+
+	if (msginfo == NULL)
+		return -ENOMEM;
+
+	ret = vmbus_negotiate_version(msginfo, vmbus_proto_version);
+
+	kfree(msginfo);
+
+	if (ret != 0)
+		return ret;
+
+	vmbus_request_offers();
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (channel->offermsg.child_relid != INVALID_RELID)
+			continue;
+
+		/* hvsock channels are not expected to be present. */
+		if (is_hvsock_channel(channel))
+			continue;
+
+		pr_err("channel %pUl/%pUl not present after resume.\n",
+		       &channel->offermsg.offer.if_type,
+		       &channel->offermsg.offer.if_instance);
+		/* ToDo: Cleanup these channels here */
+	}
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	/* Reset the event for the next suspend. */
+	reinit_completion(&vmbus_connection.ready_for_suspend_event);
+
+	return 0;
+}
+#else
+#define vmbus_bus_suspend NULL
+#define vmbus_bus_resume NULL
+#endif /* CONFIG_PM_SLEEP */
+
+static const __maybe_unused struct of_device_id vmbus_of_match[] = {
+	{
+		.compatible = "microsoft,vmbus",
+	},
+	{
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, vmbus_of_match);
+
+static const __maybe_unused struct acpi_device_id vmbus_acpi_device_ids[] = {
+	{"VMBUS", 0},
+	{"VMBus", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
+
+/*
+ * Note: we must use the "no_irq" ops, otherwise hibernation can not work with
+ * PCI device assignment, because "pci_dev_pm_ops" uses the "noirq" ops: in
+ * the resume path, the pci "noirq" restore op runs before "non-noirq" op (see
+ * resume_target_kernel() -> dpm_resume_start(), and hibernation_restore() ->
+ * dpm_resume_end()). This means vmbus_bus_resume() and the pci-hyperv's
+ * resume callback must also run via the "noirq" ops.
+ *
+ * Set suspend_noirq/resume_noirq to NULL for Suspend-to-Idle: see the comment
+ * earlier in this file before vmbus_pm.
+ */
+
+static const struct dev_pm_ops vmbus_bus_pm = {
+	.suspend_noirq	= NULL,
+	.resume_noirq	= NULL,
+	.freeze_noirq	= vmbus_bus_suspend,
+	.thaw_noirq	= vmbus_bus_resume,
+	.poweroff_noirq	= vmbus_bus_suspend,
+	.restore_noirq	= vmbus_bus_resume
+};
+
+static struct platform_driver vmbus_platform_driver = {
+	.probe = vmbus_platform_driver_probe,
+	.remove = vmbus_platform_driver_remove,
+	.driver = {
+		.name = "vmbus",
+		.acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
+		.of_match_table = of_match_ptr(vmbus_of_match),
+		.pm = &vmbus_bus_pm,
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
+	}
+};
+
+static void hv_kexec_handler(void)
+{
+	vmbus_initiate_unload(false);
+	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
+	mb();
+	cpuhp_remove_state(hyperv_cpuhp_online);
+};
+
+static void hv_crash_handler(struct pt_regs *regs)
+{
+	int cpu;
+
+	if (!skip_vmbus_unload)
+		vmbus_initiate_unload(true);
+	/*
+	 * In crash handler we can't schedule synic cleanup for all CPUs,
+	 * doing the cleanup for current CPU only. This should be sufficient
+	 * for kdump.
+	 */
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_hyp_synic_disable_regs(cpu);
+};
+
+static int hv_synic_suspend(void *data)
+{
+	/*
+	 * When we reach here, all the non-boot CPUs have been offlined.
+	 * If we're in a legacy configuration where stimer Direct Mode is
+	 * not enabled, the stimers on the non-boot CPUs have been unbound
+	 * in hv_synic_cleanup() -> hv_stimer_legacy_cleanup() ->
+	 * hv_stimer_cleanup() -> clockevents_unbind_device().
+	 *
+	 * hv_synic_suspend() only runs on CPU0 with interrupts disabled.
+	 * Here we do not call hv_stimer_legacy_cleanup() on CPU0 because:
+	 * 1) it's unnecessary as interrupts remain disabled between
+	 * syscore_suspend() and syscore_resume(): see create_image() and
+	 * resume_target_kernel()
+	 * 2) the stimer on CPU0 is automatically disabled later by
+	 * syscore_suspend() -> timekeeping_suspend() -> tick_suspend() -> ...
+	 * -> clockevents_shutdown() -> ... -> hv_ce_shutdown()
+	 * 3) a warning would be triggered if we call
+	 * clockevents_unbind_device(), which may sleep, in an
+	 * interrupts-disabled context.
+	 */
+
+	hv_hyp_synic_disable_regs(0);
+
+	return 0;
+}
+
+static void hv_synic_resume(void *data)
+{
+	hv_hyp_synic_enable_regs(0);
+
+	/*
+	 * Note: we don't need to call hv_stimer_init(0), because the timer
+	 * on CPU0 is not unbound in hv_synic_suspend(), and the timer is
+	 * automatically re-enabled in timekeeping_resume().
+	 */
+}
+
+/* The callbacks run only on CPU0, with irqs_disabled. */
+static const struct syscore_ops hv_synic_syscore_ops = {
+	.suspend = hv_synic_suspend,
+	.resume = hv_synic_resume,
+};
+
+static struct syscore hv_synic_syscore = {
+	.ops = &hv_synic_syscore_ops,
+};
+
+static int __init hv_acpi_init(void)
+{
+	int ret;
+
+	if (!hv_is_hyperv_initialized())
+		return -ENODEV;
+
+	if (hv_root_partition() && !hv_nested)
+		/*
+		 * A non-nested root partition does not need VMBus client
+		 * functionality. However, the mshv_root module may have
+		 * a dependency on the VMBus module as described in
+		 * commit 840b740a35bf. Return success so the module
+		 * loads even though no VMBus initialization is done.
+		 */
+		return 0;
+
+	/*
+	 * Get ACPI resources first.
+	 */
+	ret = platform_driver_register(&vmbus_platform_driver);
+	if (ret)
+		return ret;
+
+	if (!vmbus_root_device) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	/*
+	 * If we're on an architecture with a hardcoded hypervisor
+	 * vector (i.e. x86/x64), override the VMbus interrupt found
+	 * in the ACPI tables. Ensure vmbus_irq is not set since the
+	 * normal Linux IRQ mechanism is not used in this case.
+	 */
+#ifdef HYPERVISOR_CALLBACK_VECTOR
+	vmbus_interrupt = HYPERVISOR_CALLBACK_VECTOR;
+	vmbus_irq = -1;
+#endif
+
+	hv_debug_init();
+
+	ret = vmbus_bus_init();
+	if (ret)
+		goto cleanup;
+
+	hv_setup_kexec_handler(hv_kexec_handler);
+	hv_setup_crash_handler(hv_crash_handler);
+
+	register_syscore(&hv_synic_syscore);
+
+	return 0;
+
+cleanup:
+	platform_driver_unregister(&vmbus_platform_driver);
+	vmbus_root_device = NULL;
+	return ret;
+}
+
+static void __exit vmbus_exit(void)
+{
+	int cpu;
+
+	if (hv_root_partition() && !hv_nested)
+		/*
+		 * If a non-nested root partition loaded the VMBus module,
+		 * hv_acpi_init() did not do any VMBus initialization.
+		 * There's nothing to clean up, so just return.
+		 */
+		return;
+
+	unregister_syscore(&hv_synic_syscore);
+
+	hv_remove_kexec_handler();
+	hv_remove_crash_handler();
+	vmbus_connection.conn_state = DISCONNECTED;
+	hv_stimer_global_cleanup();
+	vmbus_disconnect();
+	if (vmbus_irq == -1)
+		hv_remove_vmbus_handler();
+	else
+		free_percpu_irq(vmbus_irq, &vmbus_evt);
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		smpboot_unregister_percpu_thread(&vmbus_irq_threads);
+
+	for_each_online_cpu(cpu) {
+		struct hv_per_cpu_context *hv_cpu
+			= per_cpu_ptr(hv_context.cpu_context, cpu);
+
+		tasklet_kill(&hv_cpu->msg_dpc);
+	}
+	hv_debug_rm_all_dir();
+
+	vmbus_free_channels();
+	kfree(vmbus_connection.channels);
+
+	/*
+	 * The vmbus panic notifier is always registered, hence we should
+	 * also unconditionally unregister it here as well.
+	 */
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					&hyperv_panic_vmbus_unload_block);
+
+	bus_unregister(&hv_bus);
+
+	cpuhp_remove_state(hyperv_cpuhp_online);
+	hv_synic_free();
+	platform_driver_unregister(&vmbus_platform_driver);
+}
+
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Microsoft Hyper-V VMBus Driver");
+
+subsys_initcall(hv_acpi_init);
+module_exit(vmbus_exit);