Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1903 insertions, 0 deletions

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
new file mode 100644
index 000000000..5cd084e56
--- /dev/null
+++ b/drivers/net/hyperv/netvsc.c
@@ -0,0 +1,1903 @@
+// 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/highmem.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+#include <linux/if_ether.h>
+#include <linux/vmalloc.h>
+#include <linux/rtnetlink.h>
+#include <linux/prefetch.h>
+#include <linux/filter.h>
+
+#include <asm/sync_bitops.h>
+#include <asm/mshyperv.h>
+
+#include "hyperv_net.h"
+#include "netvsc_trace.h"
+
+static struct workqueue_struct *netvsc_wq;
+
+/*
+ * Switch the data path from the synthetic interface to the VF
+ * interface.
+ */
+int netvsc_switch_datapath(struct net_device *ndev, bool vf)
+{
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct hv_device *dev = net_device_ctx->device_ctx;
+	struct netvsc_device *nv_dev = rtnl_dereference(net_device_ctx->nvdev);
+	struct nvsp_message *init_pkt = &nv_dev->channel_init_pkt;
+	int ret, retry = 0;
+
+	/* Block sending traffic to VF if it's about to be gone */
+	if (!vf)
+		net_device_ctx->data_path_is_vf = vf;
+
+	memset(init_pkt, 0, sizeof(struct nvsp_message));
+	init_pkt->hdr.msg_type = NVSP_MSG4_TYPE_SWITCH_DATA_PATH;
+	if (vf)
+		init_pkt->msg.v4_msg.active_dp.active_datapath =
+			NVSP_DATAPATH_VF;
+	else
+		init_pkt->msg.v4_msg.active_dp.active_datapath =
+			NVSP_DATAPATH_SYNTHETIC;
+
+again:
+	trace_nvsp_send(ndev, init_pkt);
+
+	ret = vmbus_sendpacket(dev->channel, init_pkt,
+			       sizeof(struct nvsp_message),
+			       (unsigned long)init_pkt, VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	/* If failed to switch to/from VF, let data_path_is_vf stay false,
+	 * so we use synthetic path to send data.
+	 */
+	if (ret) {
+		if (ret != -EAGAIN) {
+			netdev_err(ndev,
+				   "Unable to send sw datapath msg, err: %d\n",
+				   ret);
+			return ret;
+		}
+
+		if (retry++ < RETRY_MAX) {
+			usleep_range(RETRY_US_LO, RETRY_US_HI);
+			goto again;
+		} else {
+			netdev_err(
+				ndev,
+				"Retry failed to send sw datapath msg, err: %d\n",
+				ret);
+			return ret;
+		}
+	}
+
+	wait_for_completion(&nv_dev->channel_init_wait);
+	net_device_ctx->data_path_is_vf = vf;
+
+	return 0;
+}
+
+/* Worker to setup sub channels on initial setup
+ * Initial hotplug event occurs in softirq context
+ * and can't wait for channels.
+ */
+static void netvsc_subchan_work(struct work_struct *w)
+{
+	struct netvsc_device *nvdev =
+		container_of(w, struct netvsc_device, subchan_work);
+	struct rndis_device *rdev;
+	int i, ret;
+
+	/* Avoid deadlock with device removal already under RTNL */
+	if (!rtnl_trylock()) {
+		schedule_work(w);
+		return;
+	}
+
+	rdev = nvdev->extension;
+	if (rdev) {
+		ret = rndis_set_subchannel(rdev->ndev, nvdev, NULL);
+		if (ret == 0) {
+			netif_device_attach(rdev->ndev);
+		} else {
+			/* fallback to only primary channel */
+			for (i = 1; i < nvdev->num_chn; i++)
+				netif_napi_del(&nvdev->chan_table[i].napi);
+
+			nvdev->max_chn = 1;
+			nvdev->num_chn = 1;
+		}
+	}
+
+	rtnl_unlock();
+}
+
+static void __free_netvsc_device(struct netvsc_device *nvdev)
+{
+	int i;
+
+	kfree(nvdev->extension);
+
+	vmbus_free_buffer(nvdev->recv_buf, nvdev->recv_buf_chunks,
+			  nvdev->recv_buf_chunk_cnt);
+	vmbus_free_buffer(nvdev->send_buf, nvdev->send_buf_chunks,
+			  nvdev->send_buf_chunk_cnt);
+	bitmap_free(nvdev->send_section_map);
+
+	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
+		xdp_rxq_info_unreg(&nvdev->chan_table[i].xdp_rxq);
+		kfree(nvdev->chan_table[i].recv_buf);
+		vfree(nvdev->chan_table[i].mrc.slots);
+	}
+
+	kfree(nvdev);
+}
+
+static void free_netvsc_device(struct work_struct *w)
+{
+	struct rcu_work *rwork = to_rcu_work(w);
+
+	__free_netvsc_device(container_of(rwork, struct netvsc_device, rwork));
+}
+
+int netvsc_workqueue_init(void)
+{
+	netvsc_wq = alloc_workqueue("hv_netvsc", WQ_UNBOUND, 0);
+
+	return netvsc_wq ? 0 : -ENOMEM;
+}
+
+void netvsc_workqueue_destroy(void)
+{
+	rcu_barrier();
+	destroy_workqueue(netvsc_wq);
+}
+
+static struct netvsc_device *alloc_net_device(void)
+{
+	struct netvsc_device *net_device;
+
+	net_device = kzalloc_obj(struct netvsc_device);
+	if (!net_device)
+		return NULL;
+
+	init_waitqueue_head(&net_device->wait_drain);
+	net_device->destroy = false;
+	net_device->tx_disable = true;
+
+	net_device->max_pkt = RNDIS_MAX_PKT_DEFAULT;
+	net_device->pkt_align = RNDIS_PKT_ALIGN_DEFAULT;
+
+	init_completion(&net_device->channel_init_wait);
+	init_waitqueue_head(&net_device->subchan_open);
+	INIT_WORK(&net_device->subchan_work, netvsc_subchan_work);
+	INIT_RCU_WORK(&net_device->rwork, free_netvsc_device);
+
+	return net_device;
+}
+
+static void free_netvsc_device_rcu(struct netvsc_device *nvdev)
+{
+	/*
+	 * Defer the actual free to process context: vunmap() and
+	 * set_memory_encrypted() cannot run from RCU softirq context.
+	 */
+	queue_rcu_work(netvsc_wq, &nvdev->rwork);
+}
+
+static void netvsc_revoke_recv_buf(struct hv_device *device,
+				   struct netvsc_device *net_device,
+				   struct net_device *ndev)
+{
+	struct nvsp_message *revoke_packet;
+	int ret;
+
+	/*
+	 * If we got a section count, it means we received a
+	 * SendReceiveBufferComplete msg (ie sent
+	 * NvspMessage1TypeSendReceiveBuffer msg) therefore, we need
+	 * to send a revoke msg here
+	 */
+	if (net_device->recv_section_cnt) {
+		/* Send the revoke receive buffer */
+		revoke_packet = &net_device->revoke_packet;
+		memset(revoke_packet, 0, sizeof(struct nvsp_message));
+
+		revoke_packet->hdr.msg_type =
+			NVSP_MSG1_TYPE_REVOKE_RECV_BUF;
+		revoke_packet->msg.v1_msg.
+		revoke_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;
+
+		trace_nvsp_send(ndev, revoke_packet);
+
+		ret = vmbus_sendpacket(device->channel,
+				       revoke_packet,
+				       sizeof(struct nvsp_message),
+				       VMBUS_RQST_ID_NO_RESPONSE,
+				       VM_PKT_DATA_INBAND, 0);
+		/* If the failure is because the channel is rescinded;
+		 * ignore the failure since we cannot send on a rescinded
+		 * channel. This would allow us to properly cleanup
+		 * even when the channel is rescinded.
+		 */
+		if (device->channel->rescind)
+			ret = 0;
+		/*
+		 * If we failed here, we might as well return and
+		 * have a leak rather than continue and a bugchk
+		 */
+		if (ret != 0) {
+			netdev_err(ndev, "unable to send "
+				"revoke receive buffer to netvsp\n");
+			return;
+		}
+		net_device->recv_section_cnt = 0;
+	}
+}
+
+static void netvsc_revoke_send_buf(struct hv_device *device,
+				   struct netvsc_device *net_device,
+				   struct net_device *ndev)
+{
+	struct nvsp_message *revoke_packet;
+	int ret;
+
+	/* Deal with the send buffer we may have setup.
+	 * If we got a  send section size, it means we received a
+	 * NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE msg (ie sent
+	 * NVSP_MSG1_TYPE_SEND_SEND_BUF msg) therefore, we need
+	 * to send a revoke msg here
+	 */
+	if (net_device->send_section_cnt) {
+		/* Send the revoke receive buffer */
+		revoke_packet = &net_device->revoke_packet;
+		memset(revoke_packet, 0, sizeof(struct nvsp_message));
+
+		revoke_packet->hdr.msg_type =
+			NVSP_MSG1_TYPE_REVOKE_SEND_BUF;
+		revoke_packet->msg.v1_msg.revoke_send_buf.id =
+			NETVSC_SEND_BUFFER_ID;
+
+		trace_nvsp_send(ndev, revoke_packet);
+
+		ret = vmbus_sendpacket(device->channel,
+				       revoke_packet,
+				       sizeof(struct nvsp_message),
+				       VMBUS_RQST_ID_NO_RESPONSE,
+				       VM_PKT_DATA_INBAND, 0);
+
+		/* If the failure is because the channel is rescinded;
+		 * ignore the failure since we cannot send on a rescinded
+		 * channel. This would allow us to properly cleanup
+		 * even when the channel is rescinded.
+		 */
+		if (device->channel->rescind)
+			ret = 0;
+
+		/* If we failed here, we might as well return and
+		 * have a leak rather than continue and a bugchk
+		 */
+		if (ret != 0) {
+			netdev_err(ndev, "unable to send "
+				   "revoke send buffer to netvsp\n");
+			return;
+		}
+		net_device->send_section_cnt = 0;
+	}
+}
+
+static void netvsc_teardown_recv_gpadl(struct hv_device *device,
+				       struct netvsc_device *net_device,
+				       struct net_device *ndev)
+{
+	int ret;
+
+	if (net_device->recv_buf_gpadl_handle.gpadl_handle) {
+		ret = vmbus_teardown_gpadl(device->channel,
+					   &net_device->recv_buf_gpadl_handle);
+
+		/* If we failed here, we might as well return and have a leak
+		 * rather than continue and a bugchk
+		 */
+		if (ret != 0) {
+			netdev_err(ndev,
+				   "unable to teardown receive buffer's gpadl\n");
+			return;
+		}
+	}
+}
+
+static void netvsc_teardown_send_gpadl(struct hv_device *device,
+				       struct netvsc_device *net_device,
+				       struct net_device *ndev)
+{
+	int ret;
+
+	if (net_device->send_buf_gpadl_handle.gpadl_handle) {
+		ret = vmbus_teardown_gpadl(device->channel,
+					   &net_device->send_buf_gpadl_handle);
+
+		/* If we failed here, we might as well return and have a leak
+		 * rather than continue and a bugchk
+		 */
+		if (ret != 0) {
+			netdev_err(ndev,
+				   "unable to teardown send buffer's gpadl\n");
+			return;
+		}
+	}
+}
+
+int netvsc_alloc_recv_comp_ring(struct netvsc_device *net_device, u32 q_idx)
+{
+	struct netvsc_channel *nvchan = &net_device->chan_table[q_idx];
+	int node = cpu_to_node(nvchan->channel->target_cpu);
+	size_t size;
+
+	size = net_device->recv_completion_cnt * sizeof(struct recv_comp_data);
+	nvchan->mrc.slots = vzalloc_node(size, node);
+	if (!nvchan->mrc.slots)
+		nvchan->mrc.slots = vzalloc(size);
+
+	return nvchan->mrc.slots ? 0 : -ENOMEM;
+}
+
+static int netvsc_init_buf(struct hv_device *device,
+			   struct netvsc_device *net_device,
+			   const struct netvsc_device_info *device_info)
+{
+	struct nvsp_1_message_send_receive_buffer_complete *resp;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct nvsp_message *init_packet;
+	unsigned int buf_size;
+	int i, ret = 0;
+
+	/* Get receive buffer area. */
+	buf_size = device_info->recv_sections * device_info->recv_section_size;
+	buf_size = roundup(buf_size, PAGE_SIZE);
+
+	/* Legacy hosts only allow smaller receive buffer */
+	if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_2)
+		buf_size = min_t(unsigned int, buf_size,
+				 NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);
+
+	net_device->recv_buf =
+		vmbus_alloc_buffer(device->channel, buf_size,
+				   &net_device->recv_buf_chunks,
+				   &net_device->recv_buf_chunk_cnt);
+	if (!net_device->recv_buf) {
+		netdev_err(ndev,
+			   "unable to allocate receive buffer of size %u\n",
+			   buf_size);
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	net_device->recv_buf_size = buf_size;
+
+	/*
+	 * Establish the gpadl handle for this buffer on this
+	 * channel.  Note: This call uses the vmbus connection rather
+	 * than the channel to establish the gpadl handle.
+	 */
+	ret = vmbus_establish_gpadl_caller_decrypted(device->channel,
+						     net_device->recv_buf,
+						     buf_size,
+						     &net_device->recv_buf_gpadl_handle);
+	if (ret != 0) {
+		netdev_err(ndev,
+			"unable to establish receive buffer's gpadl\n");
+		goto cleanup;
+	}
+
+	/* Notify the NetVsp of the gpadl handle */
+	init_packet = &net_device->channel_init_pkt;
+	memset(init_packet, 0, sizeof(struct nvsp_message));
+	init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_RECV_BUF;
+	init_packet->msg.v1_msg.send_recv_buf.
+		gpadl_handle = net_device->recv_buf_gpadl_handle.gpadl_handle;
+	init_packet->msg.v1_msg.
+		send_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;
+
+	trace_nvsp_send(ndev, init_packet);
+
+	/* Send the gpadl notification request */
+	ret = vmbus_sendpacket(device->channel, init_packet,
+			       sizeof(struct nvsp_message),
+			       (unsigned long)init_packet,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret != 0) {
+		netdev_err(ndev,
+			"unable to send receive buffer's gpadl to netvsp\n");
+		goto cleanup;
+	}
+
+	wait_for_completion(&net_device->channel_init_wait);
+
+	/* Check the response */
+	resp = &init_packet->msg.v1_msg.send_recv_buf_complete;
+	if (resp->status != NVSP_STAT_SUCCESS) {
+		netdev_err(ndev,
+			   "Unable to complete receive buffer initialization with NetVsp - status %d\n",
+			   resp->status);
+		ret = -EINVAL;
+		goto cleanup;
+	}
+
+	/* Parse the response */
+	netdev_dbg(ndev, "Receive sections: %u sub_allocs: size %u count: %u\n",
+		   resp->num_sections, resp->sections[0].sub_alloc_size,
+		   resp->sections[0].num_sub_allocs);
+
+	/* There should only be one section for the entire receive buffer */
+	if (resp->num_sections != 1 || resp->sections[0].offset != 0) {
+		ret = -EINVAL;
+		goto cleanup;
+	}
+
+	net_device->recv_section_size = resp->sections[0].sub_alloc_size;
+	net_device->recv_section_cnt = resp->sections[0].num_sub_allocs;
+
+	/* Ensure buffer will not overflow */
+	if (net_device->recv_section_size < NETVSC_MTU_MIN || (u64)net_device->recv_section_size *
+	    (u64)net_device->recv_section_cnt > (u64)buf_size) {
+		netdev_err(ndev, "invalid recv_section_size %u\n",
+			   net_device->recv_section_size);
+		ret = -EINVAL;
+		goto cleanup;
+	}
+
+	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
+		struct netvsc_channel *nvchan = &net_device->chan_table[i];
+
+		nvchan->recv_buf = kzalloc(net_device->recv_section_size, GFP_KERNEL);
+		if (nvchan->recv_buf == NULL) {
+			ret = -ENOMEM;
+			goto cleanup;
+		}
+	}
+
+	/* Setup receive completion ring.
+	 * Add 1 to the recv_section_cnt because at least one entry in a
+	 * ring buffer has to be empty.
+	 */
+	net_device->recv_completion_cnt = net_device->recv_section_cnt + 1;
+	ret = netvsc_alloc_recv_comp_ring(net_device, 0);
+	if (ret)
+		goto cleanup;
+
+	/* Now setup the send buffer. */
+	buf_size = device_info->send_sections * device_info->send_section_size;
+	buf_size = round_up(buf_size, PAGE_SIZE);
+
+	net_device->send_buf =
+		vmbus_alloc_buffer(device->channel, buf_size,
+				   &net_device->send_buf_chunks,
+				   &net_device->send_buf_chunk_cnt);
+	if (!net_device->send_buf) {
+		netdev_err(ndev, "unable to allocate send buffer of size %u\n",
+			   buf_size);
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+	net_device->send_buf_size = buf_size;
+
+	/* Establish the gpadl handle for this buffer on this
+	 * channel.  Note: This call uses the vmbus connection rather
+	 * than the channel to establish the gpadl handle.
+	 */
+	ret = vmbus_establish_gpadl_caller_decrypted(device->channel,
+						     net_device->send_buf,
+						     buf_size,
+						     &net_device->send_buf_gpadl_handle);
+	if (ret != 0) {
+		netdev_err(ndev,
+			   "unable to establish send buffer's gpadl\n");
+		goto cleanup;
+	}
+
+	/* Notify the NetVsp of the gpadl handle */
+	init_packet = &net_device->channel_init_pkt;
+	memset(init_packet, 0, sizeof(struct nvsp_message));
+	init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_SEND_BUF;
+	init_packet->msg.v1_msg.send_send_buf.gpadl_handle =
+		net_device->send_buf_gpadl_handle.gpadl_handle;
+	init_packet->msg.v1_msg.send_send_buf.id = NETVSC_SEND_BUFFER_ID;
+
+	trace_nvsp_send(ndev, init_packet);
+
+	/* Send the gpadl notification request */
+	ret = vmbus_sendpacket(device->channel, init_packet,
+			       sizeof(struct nvsp_message),
+			       (unsigned long)init_packet,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret != 0) {
+		netdev_err(ndev,
+			   "unable to send send buffer's gpadl to netvsp\n");
+		goto cleanup;
+	}
+
+	wait_for_completion(&net_device->channel_init_wait);
+
+	/* Check the response */
+	if (init_packet->msg.v1_msg.
+	    send_send_buf_complete.status != NVSP_STAT_SUCCESS) {
+		netdev_err(ndev, "Unable to complete send buffer "
+			   "initialization with NetVsp - status %d\n",
+			   init_packet->msg.v1_msg.
+			   send_send_buf_complete.status);
+		ret = -EINVAL;
+		goto cleanup;
+	}
+
+	/* Parse the response */
+	net_device->send_section_size = init_packet->msg.
+				v1_msg.send_send_buf_complete.section_size;
+	if (net_device->send_section_size < NETVSC_MTU_MIN) {
+		netdev_err(ndev, "invalid send_section_size %u\n",
+			   net_device->send_section_size);
+		ret = -EINVAL;
+		goto cleanup;
+	}
+
+	/* Section count is simply the size divided by the section size. */
+	net_device->send_section_cnt = buf_size / net_device->send_section_size;
+
+	netdev_dbg(ndev, "Send section size: %d, Section count:%d\n",
+		   net_device->send_section_size, net_device->send_section_cnt);
+
+	/* Setup state for managing the send buffer. */
+	net_device->send_section_map = bitmap_zalloc(net_device->send_section_cnt,
+						     GFP_KERNEL);
+	if (!net_device->send_section_map) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	goto exit;
+
+cleanup:
+	netvsc_revoke_recv_buf(device, net_device, ndev);
+	netvsc_revoke_send_buf(device, net_device, ndev);
+	netvsc_teardown_recv_gpadl(device, net_device, ndev);
+	netvsc_teardown_send_gpadl(device, net_device, ndev);
+
+exit:
+	return ret;
+}
+
+/* Negotiate NVSP protocol version */
+static int negotiate_nvsp_ver(struct hv_device *device,
+			      struct netvsc_device *net_device,
+			      struct nvsp_message *init_packet,
+			      u32 nvsp_ver)
+{
+	struct net_device *ndev = hv_get_drvdata(device);
+	int ret;
+
+	memset(init_packet, 0, sizeof(struct nvsp_message));
+	init_packet->hdr.msg_type = NVSP_MSG_TYPE_INIT;
+	init_packet->msg.init_msg.init.min_protocol_ver = nvsp_ver;
+	init_packet->msg.init_msg.init.max_protocol_ver = nvsp_ver;
+	trace_nvsp_send(ndev, init_packet);
+
+	/* Send the init request */
+	ret = vmbus_sendpacket(device->channel, init_packet,
+			       sizeof(struct nvsp_message),
+			       (unsigned long)init_packet,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if (ret != 0)
+		return ret;
+
+	wait_for_completion(&net_device->channel_init_wait);
+
+	if (init_packet->msg.init_msg.init_complete.status !=
+	    NVSP_STAT_SUCCESS)
+		return -EINVAL;
+
+	if (nvsp_ver == NVSP_PROTOCOL_VERSION_1)
+		return 0;
+
+	/* NVSPv2 or later: Send NDIS config */
+	memset(init_packet, 0, sizeof(struct nvsp_message));
+	init_packet->hdr.msg_type = NVSP_MSG2_TYPE_SEND_NDIS_CONFIG;
+	init_packet->msg.v2_msg.send_ndis_config.mtu = ndev->mtu + ETH_HLEN;
+	init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;
+
+	if (nvsp_ver >= NVSP_PROTOCOL_VERSION_5) {
+		if (hv_is_isolation_supported())
+			netdev_info(ndev, "SR-IOV not advertised by guests on the host supporting isolation\n");
+		else
+			init_packet->msg.v2_msg.send_ndis_config.capability.sriov = 1;
+
+		/* Teaming bit is needed to receive link speed updates */
+		init_packet->msg.v2_msg.send_ndis_config.capability.teaming = 1;
+	}
+
+	if (nvsp_ver >= NVSP_PROTOCOL_VERSION_61)
+		init_packet->msg.v2_msg.send_ndis_config.capability.rsc = 1;
+
+	trace_nvsp_send(ndev, init_packet);
+
+	ret = vmbus_sendpacket(device->channel, init_packet,
+				sizeof(struct nvsp_message),
+				VMBUS_RQST_ID_NO_RESPONSE,
+				VM_PKT_DATA_INBAND, 0);
+
+	return ret;
+}
+
+static int netvsc_connect_vsp(struct hv_device *device,
+			      struct netvsc_device *net_device,
+			      const struct netvsc_device_info *device_info)
+{
+	struct net_device *ndev = hv_get_drvdata(device);
+	static const u32 ver_list[] = {
+		NVSP_PROTOCOL_VERSION_1, NVSP_PROTOCOL_VERSION_2,
+		NVSP_PROTOCOL_VERSION_4, NVSP_PROTOCOL_VERSION_5,
+		NVSP_PROTOCOL_VERSION_6, NVSP_PROTOCOL_VERSION_61
+	};
+	struct nvsp_message *init_packet;
+	int ndis_version, i, ret;
+
+	init_packet = &net_device->channel_init_pkt;
+
+	/* Negotiate the latest NVSP protocol supported */
+	for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--)
+		if (negotiate_nvsp_ver(device, net_device, init_packet,
+				       ver_list[i])  == 0) {
+			net_device->nvsp_version = ver_list[i];
+			break;
+		}
+
+	if (i < 0) {
+		ret = -EPROTO;
+		goto cleanup;
+	}
+
+	if (hv_is_isolation_supported() && net_device->nvsp_version < NVSP_PROTOCOL_VERSION_61) {
+		netdev_err(ndev, "Invalid NVSP version 0x%x (expected >= 0x%x) from the host supporting isolation\n",
+			   net_device->nvsp_version, NVSP_PROTOCOL_VERSION_61);
+		ret = -EPROTO;
+		goto cleanup;
+	}
+
+	pr_debug("Negotiated NVSP version:%x\n", net_device->nvsp_version);
+
+	/* Send the ndis version */
+	memset(init_packet, 0, sizeof(struct nvsp_message));
+
+	if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_4)
+		ndis_version = 0x00060001;
+	else
+		ndis_version = 0x0006001e;
+
+	init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_NDIS_VER;
+	init_packet->msg.v1_msg.
+		send_ndis_ver.ndis_major_ver =
+				(ndis_version & 0xFFFF0000) >> 16;
+	init_packet->msg.v1_msg.
+		send_ndis_ver.ndis_minor_ver =
+				ndis_version & 0xFFFF;
+
+	trace_nvsp_send(ndev, init_packet);
+
+	/* Send the init request */
+	ret = vmbus_sendpacket(device->channel, init_packet,
+				sizeof(struct nvsp_message),
+				VMBUS_RQST_ID_NO_RESPONSE,
+				VM_PKT_DATA_INBAND, 0);
+	if (ret != 0)
+		goto cleanup;
+
+
+	ret = netvsc_init_buf(device, net_device, device_info);
+
+cleanup:
+	return ret;
+}
+
+/*
+ * netvsc_device_remove - Callback when the root bus device is removed
+ */
+void netvsc_device_remove(struct hv_device *device)
+{
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct netvsc_device *net_device
+		= rtnl_dereference(net_device_ctx->nvdev);
+	int i;
+
+	netvsc_revoke_recv_buf(device, net_device, ndev);
+	netvsc_revoke_send_buf(device, net_device, ndev);
+
+	RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);
+
+	/* Disable NAPI and disassociate its context from the device. */
+	for (i = 0; i < net_device->num_chn; i++) {
+		/* See also vmbus_reset_channel_cb(). */
+		/* only disable enabled NAPI channel */
+		if (i < ndev->real_num_rx_queues) {
+			netif_queue_set_napi(ndev, i, NETDEV_QUEUE_TYPE_TX,
+					     NULL);
+			netif_queue_set_napi(ndev, i, NETDEV_QUEUE_TYPE_RX,
+					     NULL);
+			napi_disable(&net_device->chan_table[i].napi);
+		}
+
+		netif_napi_del(&net_device->chan_table[i].napi);
+	}
+
+	/*
+	 * At this point, no one should be accessing net_device
+	 * except in here
+	 */
+	netdev_dbg(ndev, "net device safe to remove\n");
+
+	/* Now, we can close the channel safely */
+	vmbus_close(device->channel);
+
+	/* Must do the GPADL teardown after channel is closed */
+	netvsc_teardown_recv_gpadl(device, net_device, ndev);
+	netvsc_teardown_send_gpadl(device, net_device, ndev);
+
+	/* Release all resources */
+	free_netvsc_device_rcu(net_device);
+}
+
+#define RING_AVAIL_PERCENT_HIWATER 20
+#define RING_AVAIL_PERCENT_LOWATER 10
+
+static inline void netvsc_free_send_slot(struct netvsc_device *net_device,
+					 u32 index)
+{
+	sync_change_bit(index, net_device->send_section_map);
+}
+
+static void netvsc_send_tx_complete(struct net_device *ndev,
+				    struct netvsc_device *net_device,
+				    struct vmbus_channel *channel,
+				    const struct vmpacket_descriptor *desc,
+				    int budget)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	struct sk_buff *skb;
+	u16 q_idx = 0;
+	int queue_sends;
+	u64 cmd_rqst;
+
+	cmd_rqst = channel->request_addr_callback(channel, desc->trans_id);
+	if (cmd_rqst == VMBUS_RQST_ERROR) {
+		netdev_err(ndev, "Invalid transaction ID %llx\n", desc->trans_id);
+		return;
+	}
+
+	skb = (struct sk_buff *)(unsigned long)cmd_rqst;
+
+	/* Notify the layer above us */
+	if (likely(skb)) {
+		struct hv_netvsc_packet *packet
+			= (struct hv_netvsc_packet *)skb->cb;
+		u32 send_index = packet->send_buf_index;
+		struct netvsc_stats_tx *tx_stats;
+
+		if (send_index != NETVSC_INVALID_INDEX)
+			netvsc_free_send_slot(net_device, send_index);
+		q_idx = packet->q_idx;
+
+		tx_stats = &net_device->chan_table[q_idx].tx_stats;
+
+		u64_stats_update_begin(&tx_stats->syncp);
+		tx_stats->packets += packet->total_packets;
+		tx_stats->bytes += packet->total_bytes;
+		u64_stats_update_end(&tx_stats->syncp);
+
+		netvsc_dma_unmap(ndev_ctx->device_ctx, packet);
+		napi_consume_skb(skb, budget);
+	}
+
+	queue_sends =
+		atomic_dec_return(&net_device->chan_table[q_idx].queue_sends);
+
+	if (unlikely(net_device->destroy)) {
+		if (queue_sends == 0)
+			wake_up(&net_device->wait_drain);
+	} else {
+		struct netdev_queue *txq = netdev_get_tx_queue(ndev, q_idx);
+
+		if (netif_tx_queue_stopped(txq) && !net_device->tx_disable &&
+		    (hv_get_avail_to_write_percent(&channel->outbound) >
+		     RING_AVAIL_PERCENT_HIWATER || queue_sends < 1)) {
+			netif_tx_wake_queue(txq);
+			ndev_ctx->eth_stats.wake_queue++;
+		}
+	}
+}
+
+static void netvsc_send_completion(struct net_device *ndev,
+				   struct netvsc_device *net_device,
+				   struct vmbus_channel *incoming_channel,
+				   const struct vmpacket_descriptor *desc,
+				   int budget)
+{
+	const struct nvsp_message *nvsp_packet;
+	u32 msglen = hv_pkt_datalen(desc);
+	struct nvsp_message *pkt_rqst;
+	u64 cmd_rqst;
+	u32 status;
+
+	/* First check if this is a VMBUS completion without data payload */
+	if (!msglen) {
+		cmd_rqst = incoming_channel->request_addr_callback(incoming_channel,
+								   desc->trans_id);
+		if (cmd_rqst == VMBUS_RQST_ERROR) {
+			netdev_err(ndev, "Invalid transaction ID %llx\n", desc->trans_id);
+			return;
+		}
+
+		pkt_rqst = (struct nvsp_message *)(uintptr_t)cmd_rqst;
+		switch (pkt_rqst->hdr.msg_type) {
+		case NVSP_MSG4_TYPE_SWITCH_DATA_PATH:
+			complete(&net_device->channel_init_wait);
+			break;
+
+		default:
+			netdev_err(ndev, "Unexpected VMBUS completion!!\n");
+		}
+		return;
+	}
+
+	/* Ensure packet is big enough to read header fields */
+	if (msglen < sizeof(struct nvsp_message_header)) {
+		netdev_err(ndev, "nvsp_message length too small: %u\n", msglen);
+		return;
+	}
+
+	nvsp_packet = hv_pkt_data(desc);
+	switch (nvsp_packet->hdr.msg_type) {
+	case NVSP_MSG_TYPE_INIT_COMPLETE:
+		if (msglen < sizeof(struct nvsp_message_header) +
+				sizeof(struct nvsp_message_init_complete)) {
+			netdev_err(ndev, "nvsp_msg length too small: %u\n",
+				   msglen);
+			return;
+		}
+		break;
+
+	case NVSP_MSG1_TYPE_SEND_RECV_BUF_COMPLETE:
+		if (msglen < sizeof(struct nvsp_message_header) +
+				struct_size_t(struct nvsp_1_message_send_receive_buffer_complete,
+					      sections, 1)) {
+			netdev_err(ndev, "nvsp_msg1 length too small: %u\n",
+				   msglen);
+			return;
+		}
+		break;
+
+	case NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE:
+		if (msglen < sizeof(struct nvsp_message_header) +
+				sizeof(struct nvsp_1_message_send_send_buffer_complete)) {
+			netdev_err(ndev, "nvsp_msg1 length too small: %u\n",
+				   msglen);
+			return;
+		}
+		break;
+
+	case NVSP_MSG5_TYPE_SUBCHANNEL:
+		if (msglen < sizeof(struct nvsp_message_header) +
+				sizeof(struct nvsp_5_subchannel_complete)) {
+			netdev_err(ndev, "nvsp_msg5 length too small: %u\n",
+				   msglen);
+			return;
+		}
+		break;
+
+	case NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE:
+		if (msglen < sizeof(struct nvsp_message_header) +
+		    sizeof(struct nvsp_1_message_send_rndis_packet_complete)) {
+			if (net_ratelimit())
+				netdev_err(ndev, "nvsp_rndis_pkt_complete length too small: %u\n",
+					   msglen);
+			return;
+		}
+
+		/* If status indicates an error, output a message so we know
+		 * there's a problem. But process the completion anyway so the
+		 * resources are released.
+		 */
+		status = nvsp_packet->msg.v1_msg.send_rndis_pkt_complete.status;
+		if (status != NVSP_STAT_SUCCESS && net_ratelimit())
+			netdev_err(ndev, "nvsp_rndis_pkt_complete error status: %x\n",
+				   status);
+
+		netvsc_send_tx_complete(ndev, net_device, incoming_channel,
+					desc, budget);
+		return;
+
+	default:
+		netdev_err(ndev,
+			   "Unknown send completion type %d received!!\n",
+			   nvsp_packet->hdr.msg_type);
+		return;
+	}
+
+	/* Copy the response back */
+	memcpy(&net_device->channel_init_pkt, nvsp_packet,
+	       sizeof(struct nvsp_message));
+	complete(&net_device->channel_init_wait);
+}
+
+static u32 netvsc_get_next_send_section(struct netvsc_device *net_device)
+{
+	unsigned long *map_addr = net_device->send_section_map;
+	unsigned int i;
+
+	for_each_clear_bit(i, map_addr, net_device->send_section_cnt) {
+		if (sync_test_and_set_bit(i, map_addr) == 0)
+			return i;
+	}
+
+	return NETVSC_INVALID_INDEX;
+}
+
+static void netvsc_copy_to_send_buf(struct netvsc_device *net_device,
+				    unsigned int section_index,
+				    u32 pend_size,
+				    struct hv_netvsc_packet *packet,
+				    struct rndis_message *rndis_msg,
+				    struct hv_page_buffer *pb,
+				    bool xmit_more)
+{
+	char *start = net_device->send_buf;
+	char *dest = start + (section_index * net_device->send_section_size)
+		     + pend_size;
+	int i;
+	u32 padding = 0;
+	u32 page_count = packet->cp_partial ? 1 : packet->page_buf_cnt;
+	u32 remain;
+
+	/* Add padding */
+	remain = packet->total_data_buflen & (net_device->pkt_align - 1);
+	if (xmit_more && remain) {
+		padding = net_device->pkt_align - remain;
+		rndis_msg->msg_len += padding;
+		packet->total_data_buflen += padding;
+	}
+
+	for (i = 0; i < page_count; i++) {
+		phys_addr_t paddr = (pb[i].pfn << HV_HYP_PAGE_SHIFT) +
+				    pb[i].offset;
+		u32 len = pb[i].len;
+
+		while (len) {
+			struct page *page = phys_to_page(paddr);
+			u32 off = offset_in_page(paddr);
+			u32 chunk = min_t(u32, len, PAGE_SIZE - off);
+			char *src = kmap_local_page(page);
+
+			memcpy(dest, src + off, chunk);
+			kunmap_local(src);
+			dest += chunk;
+			paddr += chunk;
+			len -= chunk;
+		}
+	}
+
+	if (padding)
+		memset(dest, 0, padding);
+}
+
+void netvsc_dma_unmap(struct hv_device *hv_dev,
+		      struct hv_netvsc_packet *packet)
+{
+	int i;
+
+	if (!hv_is_isolation_supported())
+		return;
+
+	if (!packet->dma_range)
+		return;
+
+	for (i = 0; i < packet->page_buf_cnt; i++)
+		dma_unmap_single(&hv_dev->device, packet->dma_range[i].dma,
+				 packet->dma_range[i].mapping_size,
+				 DMA_TO_DEVICE);
+
+	kfree(packet->dma_range);
+}
+
+/* netvsc_dma_map - Map swiotlb bounce buffer with data page of
+ * packet sent by vmbus_sendpacket_pagebuffer() in the Isolation
+ * VM.
+ *
+ * In isolation VM, netvsc send buffer has been marked visible to
+ * host and so the data copied to send buffer doesn't need to use
+ * bounce buffer. The data pages handled by vmbus_sendpacket_pagebuffer()
+ * may not be copied to send buffer and so these pages need to be
+ * mapped with swiotlb bounce buffer. netvsc_dma_map() is to do
+ * that. The pfns in the struct hv_page_buffer need to be converted
+ * to bounce buffer's pfn. The loop here is necessary because the
+ * entries in the page buffer array are not necessarily full
+ * pages of data.  Each entry in the array has a separate offset and
+ * len that may be non-zero, even for entries in the middle of the
+ * array.  And the entries are not physically contiguous.  So each
+ * entry must be individually mapped rather than as a contiguous unit.
+ * So not use dma_map_sg() here.
+ */
+static int netvsc_dma_map(struct hv_device *hv_dev,
+			  struct hv_netvsc_packet *packet,
+			  struct hv_page_buffer *pb)
+{
+	u32 page_count = packet->page_buf_cnt;
+	dma_addr_t dma;
+	int i;
+
+	if (!hv_is_isolation_supported())
+		return 0;
+
+	packet->dma_range = kzalloc_objs(*packet->dma_range, page_count,
+					 GFP_ATOMIC);
+	if (!packet->dma_range)
+		return -ENOMEM;
+
+	for (i = 0; i < page_count; i++) {
+		char *src = phys_to_virt((pb[i].pfn << HV_HYP_PAGE_SHIFT)
+					 + pb[i].offset);
+		u32 len = pb[i].len;
+
+		dma = dma_map_single(&hv_dev->device, src, len,
+				     DMA_TO_DEVICE);
+		if (dma_mapping_error(&hv_dev->device, dma)) {
+			kfree(packet->dma_range);
+			return -ENOMEM;
+		}
+
+		/* pb[].offset and pb[].len are not changed during dma mapping
+		 * and so not reassign.
+		 */
+		packet->dma_range[i].dma = dma;
+		packet->dma_range[i].mapping_size = len;
+		pb[i].pfn = dma >> HV_HYP_PAGE_SHIFT;
+	}
+
+	return 0;
+}
+
+/* Build an "array" of mpb entries describing the data to be transferred
+ * over VMBus. After the desc header fields, each "array" entry is variable
+ * size, and each entry starts after the end of the previous entry. The
+ * "offset" and "len" fields for each entry imply the size of the entry.
+ *
+ * The pfns are in HV_HYP_PAGE_SIZE, because all communication with Hyper-V
+ * uses that granularity, even if the system page size of the guest is larger.
+ * Each entry in the input "pb" array must describe a contiguous range of
+ * guest physical memory so that the pfns are sequential if the range crosses
+ * a page boundary. The offset field must be < HV_HYP_PAGE_SIZE.
+ */
+static inline void netvsc_build_mpb_array(struct hv_page_buffer *pb,
+				u32 page_buffer_count,
+				struct vmbus_packet_mpb_array *desc,
+				u32 *desc_size)
+{
+	struct hv_mpb_array *mpb_entry = &desc->range;
+	int i, j;
+
+	for (i = 0; i < page_buffer_count; i++) {
+		u32 offset = pb[i].offset;
+		u32 len = pb[i].len;
+
+		mpb_entry->offset = offset;
+		mpb_entry->len = len;
+
+		for (j = 0; j < HVPFN_UP(offset + len); j++)
+			mpb_entry->pfn_array[j] = pb[i].pfn + j;
+
+		mpb_entry = (struct hv_mpb_array *)&mpb_entry->pfn_array[j];
+	}
+
+	desc->rangecount = page_buffer_count;
+	*desc_size = (char *)mpb_entry - (char *)desc;
+}
+
+static inline int netvsc_send_pkt(
+	struct hv_device *device,
+	struct hv_netvsc_packet *packet,
+	struct netvsc_device *net_device,
+	struct hv_page_buffer *pb,
+	struct sk_buff *skb)
+{
+	struct nvsp_message nvmsg;
+	struct nvsp_1_message_send_rndis_packet *rpkt =
+		&nvmsg.msg.v1_msg.send_rndis_pkt;
+	struct netvsc_channel * const nvchan =
+		&net_device->chan_table[packet->q_idx];
+	struct vmbus_channel *out_channel = nvchan->channel;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	struct netdev_queue *txq = netdev_get_tx_queue(ndev, packet->q_idx);
+	u64 req_id;
+	int ret;
+	u32 ring_avail = hv_get_avail_to_write_percent(&out_channel->outbound);
+
+	memset(&nvmsg, 0, sizeof(struct nvsp_message));
+	nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
+	if (skb)
+		rpkt->channel_type = 0;		/* 0 is RMC_DATA */
+	else
+		rpkt->channel_type = 1;		/* 1 is RMC_CONTROL */
+
+	rpkt->send_buf_section_index = packet->send_buf_index;
+	if (packet->send_buf_index == NETVSC_INVALID_INDEX)
+		rpkt->send_buf_section_size = 0;
+	else
+		rpkt->send_buf_section_size = packet->total_data_buflen;
+
+	req_id = (ulong)skb;
+
+	if (out_channel->rescind)
+		return -ENODEV;
+
+	trace_nvsp_send_pkt(ndev, out_channel, rpkt);
+
+	packet->dma_range = NULL;
+	if (packet->page_buf_cnt) {
+		struct vmbus_channel_packet_page_buffer desc;
+		u32 desc_size;
+
+		if (packet->cp_partial)
+			pb++;
+
+		ret = netvsc_dma_map(ndev_ctx->device_ctx, packet, pb);
+		if (ret) {
+			ret = -EAGAIN;
+			goto exit;
+		}
+
+		netvsc_build_mpb_array(pb, packet->page_buf_cnt,
+				(struct vmbus_packet_mpb_array *)&desc,
+				 &desc_size);
+		ret = vmbus_sendpacket_mpb_desc(out_channel,
+				(struct vmbus_packet_mpb_array *)&desc,
+				desc_size, &nvmsg, sizeof(nvmsg), req_id);
+		if (ret)
+			netvsc_dma_unmap(ndev_ctx->device_ctx, packet);
+	} else {
+		ret = vmbus_sendpacket(out_channel,
+				       &nvmsg, sizeof(nvmsg),
+				       req_id, VM_PKT_DATA_INBAND,
+				       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	}
+
+exit:
+	if (ret == 0) {
+		atomic_inc_return(&nvchan->queue_sends);
+
+		if (ring_avail < RING_AVAIL_PERCENT_LOWATER) {
+			netif_tx_stop_queue(txq);
+			ndev_ctx->eth_stats.stop_queue++;
+		}
+	} else if (ret == -EAGAIN) {
+		netif_tx_stop_queue(txq);
+		ndev_ctx->eth_stats.stop_queue++;
+	} else {
+		netdev_err(ndev,
+			   "Unable to send packet pages %u len %u, ret %d\n",
+			   packet->page_buf_cnt, packet->total_data_buflen,
+			   ret);
+	}
+
+	if (netif_tx_queue_stopped(txq) &&
+	    atomic_read(&nvchan->queue_sends) < 1 &&
+	    !net_device->tx_disable) {
+		netif_tx_wake_queue(txq);
+		ndev_ctx->eth_stats.wake_queue++;
+		if (ret == -EAGAIN)
+			ret = -ENOSPC;
+	}
+
+	return ret;
+}
+
+/* Move packet out of multi send data (msd), and clear msd */
+static inline void move_pkt_msd(struct hv_netvsc_packet **msd_send,
+				struct sk_buff **msd_skb,
+				struct multi_send_data *msdp)
+{
+	*msd_skb = msdp->skb;
+	*msd_send = msdp->pkt;
+	msdp->skb = NULL;
+	msdp->pkt = NULL;
+	msdp->count = 0;
+}
+
+/* RCU already held by caller */
+/* Batching/bouncing logic is designed to attempt to optimize
+ * performance.
+ *
+ * For small, non-LSO packets we copy the packet to a send buffer
+ * which is pre-registered with the Hyper-V side. This enables the
+ * hypervisor to avoid remapping the aperture to access the packet
+ * descriptor and data.
+ *
+ * If we already started using a buffer and the netdev is transmitting
+ * a burst of packets, keep on copying into the buffer until it is
+ * full or we are done collecting a burst. If there is an existing
+ * buffer with space for the RNDIS descriptor but not the packet, copy
+ * the RNDIS descriptor to the buffer, keeping the packet in place.
+ *
+ * If we do batching and send more than one packet using a single
+ * NetVSC message, free the SKBs of the packets copied, except for the
+ * last packet. This is done to streamline the handling of the case
+ * where the last packet only had the RNDIS descriptor copied to the
+ * send buffer, with the data pointers included in the NetVSC message.
+ */
+int netvsc_send(struct net_device *ndev,
+		struct hv_netvsc_packet *packet,
+		struct rndis_message *rndis_msg,
+		struct hv_page_buffer *pb,
+		struct sk_buff *skb,
+		bool xdp_tx)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	struct netvsc_device *net_device
+		= rcu_dereference_bh(ndev_ctx->nvdev);
+	struct hv_device *device = ndev_ctx->device_ctx;
+	int ret = 0;
+	struct netvsc_channel *nvchan;
+	u32 pktlen = packet->total_data_buflen, msd_len = 0;
+	unsigned int section_index = NETVSC_INVALID_INDEX;
+	struct multi_send_data *msdp;
+	struct hv_netvsc_packet *msd_send = NULL, *cur_send = NULL;
+	struct sk_buff *msd_skb = NULL;
+	bool try_batch, xmit_more;
+
+	/* If device is rescinded, return error and packet will get dropped. */
+	if (unlikely(!net_device || net_device->destroy))
+		return -ENODEV;
+
+	nvchan = &net_device->chan_table[packet->q_idx];
+	packet->send_buf_index = NETVSC_INVALID_INDEX;
+	packet->cp_partial = false;
+
+	/* Send a control message or XDP packet directly without accessing
+	 * msd (Multi-Send Data) field which may be changed during data packet
+	 * processing.
+	 */
+	if (!skb || xdp_tx)
+		return netvsc_send_pkt(device, packet, net_device, pb, skb);
+
+	/* batch packets in send buffer if possible */
+	msdp = &nvchan->msd;
+	if (msdp->pkt)
+		msd_len = msdp->pkt->total_data_buflen;
+
+	try_batch =  msd_len > 0 && msdp->count < net_device->max_pkt;
+	if (try_batch && msd_len + pktlen + net_device->pkt_align <
+	    net_device->send_section_size) {
+		section_index = msdp->pkt->send_buf_index;
+
+	} else if (try_batch && msd_len + packet->rmsg_size <
+		   net_device->send_section_size) {
+		section_index = msdp->pkt->send_buf_index;
+		packet->cp_partial = true;
+
+	} else if (pktlen + net_device->pkt_align <
+		   net_device->send_section_size) {
+		section_index = netvsc_get_next_send_section(net_device);
+		if (unlikely(section_index == NETVSC_INVALID_INDEX)) {
+			++ndev_ctx->eth_stats.tx_send_full;
+		} else {
+			move_pkt_msd(&msd_send, &msd_skb, msdp);
+			msd_len = 0;
+		}
+	}
+
+	/* Keep aggregating only if stack says more data is coming
+	 * and not doing mixed modes send and not flow blocked
+	 */
+	xmit_more = netdev_xmit_more() &&
+		!packet->cp_partial &&
+		!netif_xmit_stopped(netdev_get_tx_queue(ndev, packet->q_idx));
+
+	if (section_index != NETVSC_INVALID_INDEX) {
+		netvsc_copy_to_send_buf(net_device,
+					section_index, msd_len,
+					packet, rndis_msg, pb, xmit_more);
+
+		packet->send_buf_index = section_index;
+
+		if (packet->cp_partial) {
+			packet->page_buf_cnt--;
+			packet->total_data_buflen = msd_len + packet->rmsg_size;
+		} else {
+			packet->page_buf_cnt = 0;
+			packet->total_data_buflen += msd_len;
+		}
+
+		if (msdp->pkt) {
+			packet->total_packets += msdp->pkt->total_packets;
+			packet->total_bytes += msdp->pkt->total_bytes;
+		}
+
+		if (msdp->skb)
+			dev_consume_skb_any(msdp->skb);
+
+		if (xmit_more) {
+			msdp->skb = skb;
+			msdp->pkt = packet;
+			msdp->count++;
+		} else {
+			cur_send = packet;
+			msdp->skb = NULL;
+			msdp->pkt = NULL;
+			msdp->count = 0;
+		}
+	} else {
+		move_pkt_msd(&msd_send, &msd_skb, msdp);
+		cur_send = packet;
+	}
+
+	if (msd_send) {
+		int m_ret = netvsc_send_pkt(device, msd_send, net_device,
+					    NULL, msd_skb);
+
+		if (m_ret != 0) {
+			netvsc_free_send_slot(net_device,
+					      msd_send->send_buf_index);
+			dev_kfree_skb_any(msd_skb);
+		}
+	}
+
+	if (cur_send)
+		ret = netvsc_send_pkt(device, cur_send, net_device, pb, skb);
+
+	if (ret != 0 && section_index != NETVSC_INVALID_INDEX)
+		netvsc_free_send_slot(net_device, section_index);
+
+	return ret;
+}
+
+/* Send pending recv completions */
+static int send_recv_completions(struct net_device *ndev,
+				 struct netvsc_device *nvdev,
+				 struct netvsc_channel *nvchan)
+{
+	struct multi_recv_comp *mrc = &nvchan->mrc;
+	struct recv_comp_msg {
+		struct nvsp_message_header hdr;
+		u32 status;
+	}  __packed;
+	struct recv_comp_msg msg = {
+		.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE,
+	};
+	int ret;
+
+	while (mrc->first != mrc->next) {
+		const struct recv_comp_data *rcd
+			= mrc->slots + mrc->first;
+
+		msg.status = rcd->status;
+		ret = vmbus_sendpacket(nvchan->channel, &msg, sizeof(msg),
+				       rcd->tid, VM_PKT_COMP, 0);
+		if (unlikely(ret)) {
+			struct net_device_context *ndev_ctx = netdev_priv(ndev);
+
+			++ndev_ctx->eth_stats.rx_comp_busy;
+			return ret;
+		}
+
+		if (++mrc->first == nvdev->recv_completion_cnt)
+			mrc->first = 0;
+	}
+
+	/* receive completion ring has been emptied */
+	if (unlikely(nvdev->destroy))
+		wake_up(&nvdev->wait_drain);
+
+	return 0;
+}
+
+/* Count how many receive completions are outstanding */
+static void recv_comp_slot_avail(const struct netvsc_device *nvdev,
+				 const struct multi_recv_comp *mrc,
+				 u32 *filled, u32 *avail)
+{
+	u32 count = nvdev->recv_completion_cnt;
+
+	if (mrc->next >= mrc->first)
+		*filled = mrc->next - mrc->first;
+	else
+		*filled = (count - mrc->first) + mrc->next;
+
+	*avail = count - *filled - 1;
+}
+
+/* Add receive complete to ring to send to host. */
+static void enq_receive_complete(struct net_device *ndev,
+				 struct netvsc_device *nvdev, u16 q_idx,
+				 u64 tid, u32 status)
+{
+	struct netvsc_channel *nvchan = &nvdev->chan_table[q_idx];
+	struct multi_recv_comp *mrc = &nvchan->mrc;
+	struct recv_comp_data *rcd;
+	u32 filled, avail;
+
+	recv_comp_slot_avail(nvdev, mrc, &filled, &avail);
+
+	if (unlikely(filled > NAPI_POLL_WEIGHT)) {
+		send_recv_completions(ndev, nvdev, nvchan);
+		recv_comp_slot_avail(nvdev, mrc, &filled, &avail);
+	}
+
+	if (unlikely(!avail)) {
+		netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
+			   q_idx, tid);
+		return;
+	}
+
+	rcd = mrc->slots + mrc->next;
+	rcd->tid = tid;
+	rcd->status = status;
+
+	if (++mrc->next == nvdev->recv_completion_cnt)
+		mrc->next = 0;
+}
+
+static int netvsc_receive(struct net_device *ndev,
+			  struct netvsc_device *net_device,
+			  struct netvsc_channel *nvchan,
+			  const struct vmpacket_descriptor *desc)
+{
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct vmbus_channel *channel = nvchan->channel;
+	const struct vmtransfer_page_packet_header *vmxferpage_packet
+		= container_of(desc, const struct vmtransfer_page_packet_header, d);
+	const struct nvsp_message *nvsp = hv_pkt_data(desc);
+	u32 msglen = hv_pkt_datalen(desc);
+	u16 q_idx = channel->offermsg.offer.sub_channel_index;
+	char *recv_buf = net_device->recv_buf;
+	u32 status = NVSP_STAT_SUCCESS;
+	int i;
+	int count = 0;
+
+	/* Ensure packet is big enough to read header fields */
+	if (msglen < sizeof(struct nvsp_message_header)) {
+		netif_err(net_device_ctx, rx_err, ndev,
+			  "invalid nvsp header, length too small: %u\n",
+			  msglen);
+		return 0;
+	}
+
+	/* Make sure this is a valid nvsp packet */
+	if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
+		netif_err(net_device_ctx, rx_err, ndev,
+			  "Unknown nvsp packet type received %u\n",
+			  nvsp->hdr.msg_type);
+		return 0;
+	}
+
+	/* Validate xfer page pkt header */
+	if ((desc->offset8 << 3) < sizeof(struct vmtransfer_page_packet_header)) {
+		netif_err(net_device_ctx, rx_err, ndev,
+			  "Invalid xfer page pkt, offset too small: %u\n",
+			  desc->offset8 << 3);
+		return 0;
+	}
+
+	if (unlikely(vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID)) {
+		netif_err(net_device_ctx, rx_err, ndev,
+			  "Invalid xfer page set id - expecting %x got %x\n",
+			  NETVSC_RECEIVE_BUFFER_ID,
+			  vmxferpage_packet->xfer_pageset_id);
+		return 0;
+	}
+
+	count = vmxferpage_packet->range_cnt;
+
+	/* Check count for a valid value */
+	if (NETVSC_XFER_HEADER_SIZE(count) > desc->offset8 << 3) {
+		netif_err(net_device_ctx, rx_err, ndev,
+			  "Range count is not valid: %d\n",
+			  count);
+		return 0;
+	}
+
+	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
+	for (i = 0; i < count; i++) {
+		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
+		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
+		void *data;
+		int ret;
+
+		if (unlikely(offset > net_device->recv_buf_size ||
+			     buflen > net_device->recv_buf_size - offset)) {
+			nvchan->rsc.cnt = 0;
+			status = NVSP_STAT_FAIL;
+			netif_err(net_device_ctx, rx_err, ndev,
+				  "Packet offset:%u + len:%u too big\n",
+				  offset, buflen);
+
+			continue;
+		}
+
+		/* We're going to copy (sections of) the packet into nvchan->recv_buf;
+		 * make sure that nvchan->recv_buf is large enough to hold the packet.
+		 */
+		if (unlikely(buflen > net_device->recv_section_size)) {
+			nvchan->rsc.cnt = 0;
+			status = NVSP_STAT_FAIL;
+			netif_err(net_device_ctx, rx_err, ndev,
+				  "Packet too big: buflen=%u recv_section_size=%u\n",
+				  buflen, net_device->recv_section_size);
+
+			continue;
+		}
+
+		data = recv_buf + offset;
+
+		nvchan->rsc.is_last = (i == count - 1);
+
+		trace_rndis_recv(ndev, q_idx, data);
+
+		/* Pass it to the upper layer */
+		ret = rndis_filter_receive(ndev, net_device,
+					   nvchan, data, buflen);
+
+		if (unlikely(ret != NVSP_STAT_SUCCESS)) {
+			/* Drop incomplete packet */
+			nvchan->rsc.cnt = 0;
+			status = NVSP_STAT_FAIL;
+		}
+	}
+
+	enq_receive_complete(ndev, net_device, q_idx,
+			     vmxferpage_packet->d.trans_id, status);
+
+	return count;
+}
+
+static void netvsc_send_table(struct net_device *ndev,
+			      struct netvsc_device *nvscdev,
+			      const struct nvsp_message *nvmsg,
+			      u32 msglen)
+{
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	u32 count, offset, *tab;
+	int i;
+
+	/* Ensure packet is big enough to read send_table fields */
+	if (msglen < sizeof(struct nvsp_message_header) +
+		     sizeof(struct nvsp_5_send_indirect_table)) {
+		netdev_err(ndev, "nvsp_v5_msg length too small: %u\n", msglen);
+		return;
+	}
+
+	count = nvmsg->msg.v5_msg.send_table.count;
+	offset = nvmsg->msg.v5_msg.send_table.offset;
+
+	if (count != VRSS_SEND_TAB_SIZE) {
+		netdev_err(ndev, "Received wrong send-table size:%u\n", count);
+		return;
+	}
+
+	/* If negotiated version <= NVSP_PROTOCOL_VERSION_6, the offset may be
+	 * wrong due to a host bug. So fix the offset here.
+	 */
+	if (nvscdev->nvsp_version <= NVSP_PROTOCOL_VERSION_6 &&
+	    msglen >= sizeof(struct nvsp_message_header) +
+	    sizeof(union nvsp_6_message_uber) + count * sizeof(u32))
+		offset = sizeof(struct nvsp_message_header) +
+			 sizeof(union nvsp_6_message_uber);
+
+	/* Boundary check for all versions */
+	if (msglen < count * sizeof(u32) || offset > msglen - count * sizeof(u32)) {
+		netdev_err(ndev, "Received send-table offset too big:%u\n",
+			   offset);
+		return;
+	}
+
+	tab = (void *)nvmsg + offset;
+
+	for (i = 0; i < count; i++)
+		net_device_ctx->tx_table[i] = tab[i];
+}
+
+static void netvsc_send_vf(struct net_device *ndev,
+			   const struct nvsp_message *nvmsg,
+			   u32 msglen)
+{
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+
+	/* Ensure packet is big enough to read its fields */
+	if (msglen < sizeof(struct nvsp_message_header) +
+		     sizeof(struct nvsp_4_send_vf_association)) {
+		netdev_err(ndev, "nvsp_v4_msg length too small: %u\n", msglen);
+		return;
+	}
+
+	net_device_ctx->vf_alloc = nvmsg->msg.v4_msg.vf_assoc.allocated;
+	net_device_ctx->vf_serial = nvmsg->msg.v4_msg.vf_assoc.serial;
+
+	if (net_device_ctx->vf_alloc)
+		complete(&net_device_ctx->vf_add);
+
+	netdev_info(ndev, "VF slot %u %s\n",
+		    net_device_ctx->vf_serial,
+		    net_device_ctx->vf_alloc ? "added" : "removed");
+}
+
+static void netvsc_receive_inband(struct net_device *ndev,
+				  struct netvsc_device *nvscdev,
+				  const struct vmpacket_descriptor *desc)
+{
+	const struct nvsp_message *nvmsg = hv_pkt_data(desc);
+	u32 msglen = hv_pkt_datalen(desc);
+
+	/* Ensure packet is big enough to read header fields */
+	if (msglen < sizeof(struct nvsp_message_header)) {
+		netdev_err(ndev, "inband nvsp_message length too small: %u\n", msglen);
+		return;
+	}
+
+	switch (nvmsg->hdr.msg_type) {
+	case NVSP_MSG5_TYPE_SEND_INDIRECTION_TABLE:
+		netvsc_send_table(ndev, nvscdev, nvmsg, msglen);
+		break;
+
+	case NVSP_MSG4_TYPE_SEND_VF_ASSOCIATION:
+		if (hv_is_isolation_supported())
+			netdev_err(ndev, "Ignore VF_ASSOCIATION msg from the host supporting isolation\n");
+		else
+			netvsc_send_vf(ndev, nvmsg, msglen);
+		break;
+	}
+}
+
+static int netvsc_process_raw_pkt(struct hv_device *device,
+				  struct netvsc_channel *nvchan,
+				  struct netvsc_device *net_device,
+				  struct net_device *ndev,
+				  const struct vmpacket_descriptor *desc,
+				  int budget)
+{
+	struct vmbus_channel *channel = nvchan->channel;
+	const struct nvsp_message *nvmsg = hv_pkt_data(desc);
+
+	trace_nvsp_recv(ndev, channel, nvmsg);
+
+	switch (desc->type) {
+	case VM_PKT_COMP:
+		netvsc_send_completion(ndev, net_device, channel, desc, budget);
+		break;
+
+	case VM_PKT_DATA_USING_XFER_PAGES:
+		return netvsc_receive(ndev, net_device, nvchan, desc);
+
+	case VM_PKT_DATA_INBAND:
+		netvsc_receive_inband(ndev, net_device, desc);
+		break;
+
+	default:
+		netdev_err(ndev, "unhandled packet type %d, tid %llx\n",
+			   desc->type, desc->trans_id);
+		break;
+	}
+
+	return 0;
+}
+
+static struct hv_device *netvsc_channel_to_device(struct vmbus_channel *channel)
+{
+	struct vmbus_channel *primary = channel->primary_channel;
+
+	return primary ? primary->device_obj : channel->device_obj;
+}
+
+/* Network processing softirq
+ * Process data in incoming ring buffer from host
+ * Stops when ring is empty or budget is met or exceeded.
+ */
+int netvsc_poll(struct napi_struct *napi, int budget)
+{
+	struct netvsc_channel *nvchan
+		= container_of(napi, struct netvsc_channel, napi);
+	struct netvsc_device *net_device = nvchan->net_device;
+	struct vmbus_channel *channel = nvchan->channel;
+	struct hv_device *device = netvsc_channel_to_device(channel);
+	struct net_device *ndev = hv_get_drvdata(device);
+	int work_done = 0;
+	int ret;
+
+	/* If starting a new interval */
+	if (!nvchan->desc)
+		nvchan->desc = hv_pkt_iter_first(channel);
+
+	nvchan->xdp_flush = false;
+
+	while (nvchan->desc && work_done < budget) {
+		work_done += netvsc_process_raw_pkt(device, nvchan, net_device,
+						    ndev, nvchan->desc, budget);
+		nvchan->desc = hv_pkt_iter_next(channel, nvchan->desc);
+	}
+
+	if (nvchan->xdp_flush)
+		xdp_do_flush();
+
+	/* Send any pending receive completions */
+	ret = send_recv_completions(ndev, net_device, nvchan);
+
+	/* If it did not exhaust NAPI budget this time
+	 *  and not doing busy poll
+	 * then re-enable host interrupts
+	 *  and reschedule if ring is not empty
+	 *   or sending receive completion failed.
+	 */
+	if (work_done < budget &&
+	    napi_complete_done(napi, work_done) &&
+	    (ret || hv_end_read(&channel->inbound)) &&
+	    napi_schedule_prep(napi)) {
+		hv_begin_read(&channel->inbound);
+		__napi_schedule(napi);
+	}
+
+	/* Driver may overshoot since multiple packets per descriptor */
+	return min(work_done, budget);
+}
+
+/* Call back when data is available in host ring buffer.
+ * Processing is deferred until network softirq (NAPI)
+ */
+void netvsc_channel_cb(void *context)
+{
+	struct netvsc_channel *nvchan = context;
+	struct vmbus_channel *channel = nvchan->channel;
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+
+	/* preload first vmpacket descriptor */
+	prefetch(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
+
+	if (napi_schedule_prep(&nvchan->napi)) {
+		/* disable interrupts from host */
+		hv_begin_read(rbi);
+
+		__napi_schedule_irqoff(&nvchan->napi);
+	}
+}
+
+/*
+ * netvsc_device_add - Callback when the device belonging to this
+ * driver is added
+ */
+struct netvsc_device *netvsc_device_add(struct hv_device *device,
+				const struct netvsc_device_info *device_info)
+{
+	int i, ret = 0;
+	struct netvsc_device *net_device;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+
+	net_device = alloc_net_device();
+	if (!net_device)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < VRSS_SEND_TAB_SIZE; i++)
+		net_device_ctx->tx_table[i] = 0;
+
+	/* Because the device uses NAPI, all the interrupt batching and
+	 * control is done via Net softirq, not the channel handling
+	 */
+	set_channel_read_mode(device->channel, HV_CALL_ISR);
+
+	/* If we're reopening the device we may have multiple queues, fill the
+	 * chn_table with the default channel to use it before subchannels are
+	 * opened.
+	 * Initialize the channel state before we open;
+	 * we can be interrupted as soon as we open the channel.
+	 */
+
+	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
+		struct netvsc_channel *nvchan = &net_device->chan_table[i];
+
+		nvchan->channel = device->channel;
+		nvchan->net_device = net_device;
+		u64_stats_init(&nvchan->tx_stats.syncp);
+		u64_stats_init(&nvchan->rx_stats.syncp);
+
+		ret = xdp_rxq_info_reg(&nvchan->xdp_rxq, ndev, i, 0);
+
+		if (ret) {
+			netdev_err(ndev, "xdp_rxq_info_reg fail: %d\n", ret);
+			goto cleanup2;
+		}
+
+		ret = xdp_rxq_info_reg_mem_model(&nvchan->xdp_rxq,
+						 MEM_TYPE_PAGE_SHARED, NULL);
+
+		if (ret) {
+			netdev_err(ndev, "xdp reg_mem_model fail: %d\n", ret);
+			goto cleanup2;
+		}
+	}
+
+	/* Enable NAPI handler before init callbacks */
+	netif_napi_add(ndev, &net_device->chan_table[0].napi, netvsc_poll);
+	napi_enable(&net_device->chan_table[0].napi);
+	netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_RX,
+			     &net_device->chan_table[0].napi);
+	netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_TX,
+			     &net_device->chan_table[0].napi);
+
+	/* Open the channel */
+	device->channel->next_request_id_callback = vmbus_next_request_id;
+	device->channel->request_addr_callback = vmbus_request_addr;
+	device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
+	device->channel->max_pkt_size = NETVSC_MAX_PKT_SIZE;
+
+	ret = vmbus_open(device->channel, netvsc_ring_bytes,
+			 netvsc_ring_bytes,  NULL, 0,
+			 netvsc_channel_cb, net_device->chan_table);
+
+	if (ret != 0) {
+		netdev_err(ndev, "unable to open channel: %d\n", ret);
+		goto cleanup;
+	}
+
+	/* Channel is opened */
+	netdev_dbg(ndev, "hv_netvsc channel opened successfully\n");
+
+	/* Connect with the NetVsp */
+	ret = netvsc_connect_vsp(device, net_device, device_info);
+	if (ret != 0) {
+		netdev_err(ndev,
+			"unable to connect to NetVSP - %d\n", ret);
+		goto close;
+	}
+
+	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
+	 * populated.
+	 */
+	rcu_assign_pointer(net_device_ctx->nvdev, net_device);
+
+	return net_device;
+
+close:
+	RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);
+
+	/* Now, we can close the channel safely */
+	vmbus_close(device->channel);
+
+cleanup:
+	netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_TX, NULL);
+	netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_RX, NULL);
+	napi_disable(&net_device->chan_table[0].napi);
+	netif_napi_del(&net_device->chan_table[0].napi);
+
+cleanup2:
+	/*
+	 * net_device was never published, so we don't need to wait for an
+	 * RCU grace period -- call the free routine synchronously.
+	 */
+	__free_netvsc_device(net_device);
+
+	return ERR_PTR(ret);
+}