Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted

Pull I3C updates from Alexandre Belloni:
 "A new driver this cycle, for the AMD AXI I3C controller.

  There are also new features such as IBI wakeup support, SETAASA device
  discovery and ACPI support for the the DAA methods, meaning we can now
  communicate with the SPD devices on DDR5 modules.

  New driver:
   - AMD AXI I3C master controller

  Subsystem:
   - I3C Common Command Code (CCC) handling improvements, especially
     around GET CCCs
   - SETAASA device discovery support
   - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
     well as I2C devices on I3C bus
   - IBI-based wakeup support

  Drivers:
   - dw: SETAASA support
   - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
     controller support, PIO queue management support for HCI v1.2
   - renesas: improve suspend to RAM support, add runtime PM support"

* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
  i3c: dw: reduce do_daa time if there's no client
  i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
  i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
  i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
  i3c: dw: rename "pclk" to "apb" to match dt-binding
  i3c: dw: make struct dw_i3c_cmd smaller
  i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
  i3c: renesas: Don't register devices when ENTDAA times out
  i3c: master: dw-i3c-master: fix OD timing for first broadcast
  i3c: mipi-i3c-hci: Advertise IBI wakeup capability
  i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
  i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
  i3c: master: Reject IBI requests from non-IBI-capable devices
  i3c: master: Add helper to query bus wakeup requirements
  i3c: master: Report wakeup events for IBIs
  i3c: master: Support IBI-based wakeup capability
  i3c: master: Fix potential UAF in i3c_device_match()
  i3c: master: Fix potential UAF in i3c_device_uevent()
  i3c: Make dev->desc locking assumptions explicit
  i3c: master: Fix use-after-free of master->this
  ...

16 files changed, 11408 insertions, 0 deletions

diff --git a/net/vmw_vsock/Kconfig b/net/vmw_vsock/Kconfig
new file mode 100644
index 000000000..8e803c482
--- /dev/null
+++ b/net/vmw_vsock/Kconfig
@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Vsock protocol
+#
+
+config VSOCKETS
+	tristate "Virtual Socket protocol"
+	help
+	  Virtual Socket Protocol is a socket protocol similar to TCP/IP
+	  allowing communication between Virtual Machines and hypervisor
+	  or host.
+
+	  You should also select one or more hypervisor-specific transports
+	  below.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called vsock. If unsure, say N.
+
+config VSOCKETS_DIAG
+	tristate "Virtual Sockets monitoring interface"
+	depends on VSOCKETS
+	default y
+	help
+	  Support for PF_VSOCK sockets monitoring interface used by the ss tool.
+	  If unsure, say Y.
+
+	  Enable this module so userspace applications can query open sockets.
+
+config VSOCKETS_LOOPBACK
+	tristate "Virtual Sockets loopback transport"
+	depends on VSOCKETS
+	default y
+	select VIRTIO_VSOCKETS_COMMON
+	help
+	  This module implements a loopback transport for Virtual Sockets,
+	  using vmw_vsock_virtio_transport_common.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called vsock_loopback. If unsure, say N.
+
+config VMWARE_VMCI_VSOCKETS
+	tristate "VMware VMCI transport for Virtual Sockets"
+	depends on VSOCKETS && VMWARE_VMCI
+	help
+	  This module implements a VMCI transport for Virtual Sockets.
+
+	  Enable this transport if your Virtual Machine runs on a VMware
+	  hypervisor.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called vmw_vsock_vmci_transport. If unsure, say N.
+
+config VIRTIO_VSOCKETS
+	tristate "virtio transport for Virtual Sockets"
+	depends on VSOCKETS && VIRTIO
+	select VIRTIO_VSOCKETS_COMMON
+	help
+	  This module implements a virtio transport for Virtual Sockets.
+
+	  Enable this transport if your Virtual Machine host supports Virtual
+	  Sockets over virtio.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called vmw_vsock_virtio_transport. If unsure, say N.
+
+config VIRTIO_VSOCKETS_COMMON
+	tristate
+	help
+	  This option is selected by any driver which needs to access
+	  the virtio_vsock.  The module will be called
+	  vmw_vsock_virtio_transport_common.
+
+config HYPERV_VSOCKETS
+	tristate "Hyper-V transport for Virtual Sockets"
+	depends on VSOCKETS && HYPERV_VMBUS
+	help
+	  This module implements a Hyper-V transport for Virtual Sockets.
+
+	  Enable this transport if your Virtual Machine host supports Virtual
+	  Sockets over Hyper-V VMBus.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called hv_sock. If unsure, say N.
diff --git a/net/vmw_vsock/Makefile b/net/vmw_vsock/Makefile
new file mode 100644
index 000000000..5da74c4a9
--- /dev/null
+++ b/net/vmw_vsock/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_VSOCKETS) += vsock.o
+obj-$(CONFIG_VSOCKETS_DIAG) += vsock_diag.o
+obj-$(CONFIG_VMWARE_VMCI_VSOCKETS) += vmw_vsock_vmci_transport.o
+obj-$(CONFIG_VIRTIO_VSOCKETS) += vmw_vsock_virtio_transport.o
+obj-$(CONFIG_VIRTIO_VSOCKETS_COMMON) += vmw_vsock_virtio_transport_common.o
+obj-$(CONFIG_HYPERV_VSOCKETS) += hv_sock.o
+obj-$(CONFIG_VSOCKETS_LOOPBACK) += vsock_loopback.o
+
+vsock-y += af_vsock.o af_vsock_tap.o vsock_addr.o
+vsock-$(CONFIG_BPF_SYSCALL) += vsock_bpf.o
+
+vsock_diag-y += diag.o
+
+vmw_vsock_vmci_transport-y += vmci_transport.o vmci_transport_notify.o \
+	vmci_transport_notify_qstate.o
+
+vmw_vsock_virtio_transport-y += virtio_transport.o
+
+vmw_vsock_virtio_transport_common-y += virtio_transport_common.o
+
+hv_sock-y += hyperv_transport.o
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
new file mode 100644
index 000000000..a33b2a2d3
--- /dev/null
+++ b/net/vmw_vsock/af_vsock.c
@@ -0,0 +1,3131 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2007-2013 VMware, Inc. All rights reserved.
+ */
+
+/* Implementation notes:
+ *
+ * - There are two kinds of sockets: those created by user action (such as
+ * calling socket(2)) and those created by incoming connection request packets.
+ *
+ * - There are two "global" tables, one for bound sockets (sockets that have
+ * specified an address that they are responsible for) and one for connected
+ * sockets (sockets that have established a connection with another socket).
+ * These tables are "global" in that all sockets on the system are placed
+ * within them. - Note, though, that the bound table contains an extra entry
+ * for a list of unbound sockets and SOCK_DGRAM sockets will always remain in
+ * that list. The bound table is used solely for lookup of sockets when packets
+ * are received and that's not necessary for SOCK_DGRAM sockets since we create
+ * a datagram handle for each and need not perform a lookup.  Keeping SOCK_DGRAM
+ * sockets out of the bound hash buckets will reduce the chance of collisions
+ * when looking for SOCK_STREAM sockets and prevents us from having to check the
+ * socket type in the hash table lookups.
+ *
+ * - Sockets created by user action will either be "client" sockets that
+ * initiate a connection or "server" sockets that listen for connections; we do
+ * not support simultaneous connects (two "client" sockets connecting).
+ *
+ * - "Server" sockets are referred to as listener sockets throughout this
+ * implementation because they are in the TCP_LISTEN state.  When a
+ * connection request is received (the second kind of socket mentioned above),
+ * we create a new socket and refer to it as a pending socket.  These pending
+ * sockets are placed on the pending connection list of the listener socket.
+ * When future packets are received for the address the listener socket is
+ * bound to, we check if the source of the packet is from one that has an
+ * existing pending connection.  If it does, we process the packet for the
+ * pending socket.  When that socket reaches the connected state, it is removed
+ * from the listener socket's pending list and enqueued in the listener
+ * socket's accept queue.  Callers of accept(2) will accept connected sockets
+ * from the listener socket's accept queue. Once the connection is accepted,
+ * it is owned by the user process and the responsibility for cleanup falls
+ * with that user process.
+ *
+ * - It is possible that these pending sockets will never reach the connected
+ * state; in fact, we may never receive another packet after the connection
+ * request.  Because of this, we must schedule a cleanup function to run in the
+ * future, after some amount of time passes where a connection should have been
+ * established.  This function ensures that the socket is off all lists so it
+ * cannot be retrieved, then drops all references to the socket so it is cleaned
+ * up (sock_put() -> sk_free() -> our sk_destruct implementation).
+ *
+ * - Lock ordering for pending or accept queue sockets is:
+ *
+ *     lock_sock(listener);
+ *     lock_sock_nested(pending, SINGLE_DEPTH_NESTING);
+ *
+ * Using explicit nested locking keeps lockdep happy since normally only one
+ * lock of a given class may be taken at a time.
+ *
+ * - Sockets created by user action will be cleaned up when the user process
+ * calls close(2), causing our release implementation to be called. Our release
+ * implementation will perform some cleanup then drop the last reference so our
+ * sk_destruct implementation is invoked.  Our sk_destruct implementation will
+ * perform additional cleanup that's common for both types of sockets.
+ *
+ * - A socket's reference count is what ensures that the structure won't be
+ * freed.  Each entry in a list (such as the "global" bound and connected tables
+ * and the listener socket's pending list and connected queue) ensures a
+ * reference.  When we defer work until process context and pass a socket as our
+ * argument, we must ensure the reference count is increased to ensure the
+ * socket isn't freed before the function is run; the deferred function will
+ * then drop the reference.
+ *
+ * - sk->sk_state uses the TCP state constants because they are widely used by
+ * other address families and exposed to userspace tools like ss(8):
+ *
+ *   TCP_CLOSE - unconnected
+ *   TCP_SYN_SENT - connecting
+ *   TCP_ESTABLISHED - connected
+ *   TCP_CLOSING - disconnecting
+ *   TCP_LISTEN - listening
+ *
+ * - Namespaces in vsock support two different modes: "local" and "global".
+ *   Each mode defines how the namespace interacts with CIDs.
+ *   Each namespace exposes two sysctl files:
+ *
+ *   - /proc/sys/net/vsock/ns_mode (read-only) reports the current namespace's
+ *     mode, which is set at namespace creation and immutable thereafter.
+ *   - /proc/sys/net/vsock/child_ns_mode (write-once) controls what mode future
+ *     child namespaces will inherit when created. The initial value matches
+ *     the namespace's own ns_mode.
+ *
+ *   Changing child_ns_mode only affects newly created namespaces, not the
+ *   current namespace or existing children. A "local" namespace cannot set
+ *   child_ns_mode to "global". child_ns_mode is write-once, so that it may be
+ *   configured and locked down by a namespace manager. Writing a different
+ *   value after the first write returns -EBUSY. At namespace creation, ns_mode
+ *   is inherited from the parent's child_ns_mode.
+ *
+ *   The init_net mode is "global" and cannot be modified. The init_net
+ *   child_ns_mode is also write-once, so an init process (e.g. systemd) can
+ *   set it to "local" to ensure all new namespaces inherit local mode.
+ *
+ *   The modes affect the allocation and accessibility of CIDs as follows:
+ *
+ *   - global - access and allocation are all system-wide
+ *      - all CID allocation from global namespaces draw from the same
+ *        system-wide pool.
+ *      - if one global namespace has already allocated some CID, another
+ *        global namespace will not be able to allocate the same CID.
+ *      - global mode AF_VSOCK sockets can reach any VM or socket in any global
+ *        namespace, they are not contained to only their own namespace.
+ *      - AF_VSOCK sockets in a global mode namespace cannot reach VMs or
+ *        sockets in any local mode namespace.
+ *   - local - access and allocation are contained within the namespace
+ *     - CID allocation draws only from a private pool local only to the
+ *       namespace, and does not affect the CIDs available for allocation in any
+ *       other namespace (global or local).
+ *     - VMs in a local namespace do not collide with CIDs in any other local
+ *       namespace or any global namespace. For example, if a VM in a local mode
+ *       namespace is given CID 10, then CID 10 is still available for
+ *       allocation in any other namespace, but not in the same namespace.
+ *     - AF_VSOCK sockets in a local mode namespace can connect only to VMs or
+ *       other sockets within their own namespace.
+ *     - sockets bound to VMADDR_CID_ANY in local namespaces will never resolve
+ *       to any transport that is not compatible with local mode. There is no
+ *       error that propagates to the user (as there is for connection attempts)
+ *       because it is possible for some packet to reach this socket from
+ *       a different transport that *does* support local mode. For
+ *       example, virtio-vsock may not support local mode, but the socket
+ *       may still accept a connection from vhost-vsock which does.
+ */
+
+#include <linux/compat.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/cred.h>
+#include <linux/errqueue.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/sched/signal.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/net.h>
+#include <linux/proc_fs.h>
+#include <linux/poll.h>
+#include <linux/random.h>
+#include <linux/skbuff.h>
+#include <linux/smp.h>
+#include <linux/uio.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <linux/sysctl.h>
+#include <linux/unistd.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <net/sock.h>
+#include <net/af_vsock.h>
+#include <net/netns/vsock.h>
+#include <uapi/linux/vm_sockets.h>
+#include <uapi/asm-generic/ioctls.h>
+
+#define VSOCK_NET_MODE_STR_GLOBAL "global"
+#define VSOCK_NET_MODE_STR_LOCAL "local"
+
+/* 6 chars for "global", 1 for null-terminator, and 1 more for '\n'.
+ * The newline is added by proc_dostring() for read operations.
+ */
+#define VSOCK_NET_MODE_STR_MAX 8
+
+static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
+static void vsock_sk_destruct(struct sock *sk);
+static int vsock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
+static void vsock_close(struct sock *sk, long timeout);
+
+/* Protocol family. */
+struct proto vsock_proto = {
+	.name = "AF_VSOCK",
+	.owner = THIS_MODULE,
+	.obj_size = sizeof(struct vsock_sock),
+	.close = vsock_close,
+#ifdef CONFIG_BPF_SYSCALL
+	.psock_update_sk_prot = vsock_bpf_update_proto,
+#endif
+};
+
+/* The default peer timeout indicates how long we will wait for a peer response
+ * to a control message.
+ */
+#define VSOCK_DEFAULT_CONNECT_TIMEOUT (2 * HZ)
+
+#define VSOCK_DEFAULT_BUFFER_SIZE     (1024 * 256)
+#define VSOCK_DEFAULT_BUFFER_MAX_SIZE (1024 * 256)
+#define VSOCK_DEFAULT_BUFFER_MIN_SIZE 128
+
+/* Transport used for host->guest communication */
+static const struct vsock_transport *transport_h2g;
+/* Transport used for guest->host communication */
+static const struct vsock_transport *transport_g2h;
+/* Transport used for DGRAM communication */
+static const struct vsock_transport *transport_dgram;
+/* Transport used for local communication */
+static const struct vsock_transport *transport_local;
+static DEFINE_MUTEX(vsock_register_mutex);
+
+/**** UTILS ****/
+
+/* Each bound VSocket is stored in the bind hash table and each connected
+ * VSocket is stored in the connected hash table.
+ *
+ * Unbound sockets are all put on the same list attached to the end of the hash
+ * table (vsock_unbound_sockets).  Bound sockets are added to the hash table in
+ * the bucket that their local address hashes to (vsock_bound_sockets(addr)
+ * represents the list that addr hashes to).
+ *
+ * Specifically, we initialize the vsock_bind_table array to a size of
+ * VSOCK_HASH_SIZE + 1 so that vsock_bind_table[0] through
+ * vsock_bind_table[VSOCK_HASH_SIZE - 1] are for bound sockets and
+ * vsock_bind_table[VSOCK_HASH_SIZE] is for unbound sockets.  The hash function
+ * mods with VSOCK_HASH_SIZE to ensure this.
+ */
+#define MAX_PORT_RETRIES        24
+
+#define VSOCK_HASH(addr)        ((addr)->svm_port % VSOCK_HASH_SIZE)
+#define vsock_bound_sockets(addr) (&vsock_bind_table[VSOCK_HASH(addr)])
+#define vsock_unbound_sockets     (&vsock_bind_table[VSOCK_HASH_SIZE])
+
+/* XXX This can probably be implemented in a better way. */
+#define VSOCK_CONN_HASH(src, dst)				\
+	(((src)->svm_cid ^ (dst)->svm_port) % VSOCK_HASH_SIZE)
+#define vsock_connected_sockets(src, dst)		\
+	(&vsock_connected_table[VSOCK_CONN_HASH(src, dst)])
+#define vsock_connected_sockets_vsk(vsk)				\
+	vsock_connected_sockets(&(vsk)->remote_addr, &(vsk)->local_addr)
+
+struct list_head vsock_bind_table[VSOCK_HASH_SIZE + 1];
+EXPORT_SYMBOL_GPL(vsock_bind_table);
+struct list_head vsock_connected_table[VSOCK_HASH_SIZE];
+EXPORT_SYMBOL_GPL(vsock_connected_table);
+DEFINE_SPINLOCK(vsock_table_lock);
+EXPORT_SYMBOL_GPL(vsock_table_lock);
+
+/* Autobind this socket to the local address if necessary. */
+static int vsock_auto_bind(struct vsock_sock *vsk)
+{
+	struct sock *sk = sk_vsock(vsk);
+	struct sockaddr_vm local_addr;
+
+	if (vsock_addr_bound(&vsk->local_addr))
+		return 0;
+	vsock_addr_init(&local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
+	return __vsock_bind(sk, &local_addr);
+}
+
+static void vsock_init_tables(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vsock_bind_table); i++)
+		INIT_LIST_HEAD(&vsock_bind_table[i]);
+
+	for (i = 0; i < ARRAY_SIZE(vsock_connected_table); i++)
+		INIT_LIST_HEAD(&vsock_connected_table[i]);
+}
+
+static void __vsock_insert_bound(struct list_head *list,
+				 struct vsock_sock *vsk)
+{
+	sock_hold(&vsk->sk);
+	list_add(&vsk->bound_table, list);
+}
+
+static void __vsock_insert_connected(struct list_head *list,
+				     struct vsock_sock *vsk)
+{
+	sock_hold(&vsk->sk);
+	list_add(&vsk->connected_table, list);
+}
+
+static void __vsock_remove_bound(struct vsock_sock *vsk)
+{
+	list_del_init(&vsk->bound_table);
+	sock_put(&vsk->sk);
+}
+
+static void __vsock_remove_connected(struct vsock_sock *vsk)
+{
+	list_del_init(&vsk->connected_table);
+	sock_put(&vsk->sk);
+}
+
+static struct sock *__vsock_find_bound_socket_net(struct sockaddr_vm *addr,
+						  struct net *net)
+{
+	struct vsock_sock *vsk;
+
+	list_for_each_entry(vsk, vsock_bound_sockets(addr), bound_table) {
+		struct sock *sk = sk_vsock(vsk);
+
+		if (vsock_addr_equals_addr(addr, &vsk->local_addr) &&
+		    vsock_net_check_mode(sock_net(sk), net))
+			return sk;
+
+		if (addr->svm_port == vsk->local_addr.svm_port &&
+		    (vsk->local_addr.svm_cid == VMADDR_CID_ANY ||
+		     addr->svm_cid == VMADDR_CID_ANY) &&
+		     vsock_net_check_mode(sock_net(sk), net))
+			return sk;
+	}
+
+	return NULL;
+}
+
+static struct sock *
+__vsock_find_connected_socket_net(struct sockaddr_vm *src,
+				  struct sockaddr_vm *dst, struct net *net)
+{
+	struct vsock_sock *vsk;
+
+	list_for_each_entry(vsk, vsock_connected_sockets(src, dst),
+			    connected_table) {
+		struct sock *sk = sk_vsock(vsk);
+
+		if (vsock_addr_equals_addr(src, &vsk->remote_addr) &&
+		    dst->svm_port == vsk->local_addr.svm_port &&
+		    vsock_net_check_mode(sock_net(sk), net)) {
+			return sk;
+		}
+	}
+
+	return NULL;
+}
+
+static void vsock_insert_unbound(struct vsock_sock *vsk)
+{
+	spin_lock_bh(&vsock_table_lock);
+	__vsock_insert_bound(vsock_unbound_sockets, vsk);
+	spin_unlock_bh(&vsock_table_lock);
+}
+
+void vsock_insert_connected(struct vsock_sock *vsk)
+{
+	struct list_head *list = vsock_connected_sockets(
+		&vsk->remote_addr, &vsk->local_addr);
+
+	spin_lock_bh(&vsock_table_lock);
+	__vsock_insert_connected(list, vsk);
+	spin_unlock_bh(&vsock_table_lock);
+}
+EXPORT_SYMBOL_GPL(vsock_insert_connected);
+
+void vsock_remove_bound(struct vsock_sock *vsk)
+{
+	spin_lock_bh(&vsock_table_lock);
+	if (__vsock_in_bound_table(vsk))
+		__vsock_remove_bound(vsk);
+	spin_unlock_bh(&vsock_table_lock);
+}
+EXPORT_SYMBOL_GPL(vsock_remove_bound);
+
+void vsock_remove_connected(struct vsock_sock *vsk)
+{
+	spin_lock_bh(&vsock_table_lock);
+	if (__vsock_in_connected_table(vsk))
+		__vsock_remove_connected(vsk);
+	spin_unlock_bh(&vsock_table_lock);
+}
+EXPORT_SYMBOL_GPL(vsock_remove_connected);
+
+/* Find a bound socket, filtering by namespace and namespace mode.
+ *
+ * Use this in transports that are namespace-aware and can provide the
+ * network namespace context.
+ */
+struct sock *vsock_find_bound_socket_net(struct sockaddr_vm *addr,
+					 struct net *net)
+{
+	struct sock *sk;
+
+	spin_lock_bh(&vsock_table_lock);
+	sk = __vsock_find_bound_socket_net(addr, net);
+	if (sk)
+		sock_hold(sk);
+
+	spin_unlock_bh(&vsock_table_lock);
+
+	return sk;
+}
+EXPORT_SYMBOL_GPL(vsock_find_bound_socket_net);
+
+/* Find a bound socket without namespace filtering.
+ *
+ * Use this in transports that lack namespace context. All sockets are
+ * treated as if in global mode.
+ */
+struct sock *vsock_find_bound_socket(struct sockaddr_vm *addr)
+{
+	return vsock_find_bound_socket_net(addr, NULL);
+}
+EXPORT_SYMBOL_GPL(vsock_find_bound_socket);
+
+/* Find a connected socket, filtering by namespace and namespace mode.
+ *
+ * Use this in transports that are namespace-aware and can provide the
+ * network namespace context.
+ */
+struct sock *vsock_find_connected_socket_net(struct sockaddr_vm *src,
+					     struct sockaddr_vm *dst,
+					     struct net *net)
+{
+	struct sock *sk;
+
+	spin_lock_bh(&vsock_table_lock);
+	sk = __vsock_find_connected_socket_net(src, dst, net);
+	if (sk)
+		sock_hold(sk);
+
+	spin_unlock_bh(&vsock_table_lock);
+
+	return sk;
+}
+EXPORT_SYMBOL_GPL(vsock_find_connected_socket_net);
+
+/* Find a connected socket without namespace filtering.
+ *
+ * Use this in transports that lack namespace context. All sockets are
+ * treated as if in global mode.
+ */
+struct sock *vsock_find_connected_socket(struct sockaddr_vm *src,
+					 struct sockaddr_vm *dst)
+{
+	return vsock_find_connected_socket_net(src, dst, NULL);
+}
+EXPORT_SYMBOL_GPL(vsock_find_connected_socket);
+
+void vsock_remove_sock(struct vsock_sock *vsk)
+{
+	/* Transport reassignment must not remove the binding. */
+	if (sock_flag(sk_vsock(vsk), SOCK_DEAD))
+		vsock_remove_bound(vsk);
+
+	vsock_remove_connected(vsk);
+}
+EXPORT_SYMBOL_GPL(vsock_remove_sock);
+
+void vsock_for_each_connected_socket(struct vsock_transport *transport,
+				     void (*fn)(struct sock *sk))
+{
+	int i;
+
+	spin_lock_bh(&vsock_table_lock);
+
+	for (i = 0; i < ARRAY_SIZE(vsock_connected_table); i++) {
+		struct vsock_sock *vsk;
+		list_for_each_entry(vsk, &vsock_connected_table[i],
+				    connected_table) {
+			if (vsk->transport != transport)
+				continue;
+
+			fn(sk_vsock(vsk));
+		}
+	}
+
+	spin_unlock_bh(&vsock_table_lock);
+}
+EXPORT_SYMBOL_GPL(vsock_for_each_connected_socket);
+
+void vsock_add_pending(struct sock *listener, struct sock *pending)
+{
+	struct vsock_sock *vlistener;
+	struct vsock_sock *vpending;
+
+	vlistener = vsock_sk(listener);
+	vpending = vsock_sk(pending);
+
+	sock_hold(pending);
+	sock_hold(listener);
+	list_add_tail(&vpending->pending_links, &vlistener->pending_links);
+	sk_acceptq_added(listener);
+}
+EXPORT_SYMBOL_GPL(vsock_add_pending);
+
+void vsock_remove_pending(struct sock *listener, struct sock *pending)
+{
+	struct vsock_sock *vpending = vsock_sk(pending);
+
+	list_del_init(&vpending->pending_links);
+	sock_put(listener);
+	sock_put(pending);
+	sk_acceptq_removed(listener);
+}
+EXPORT_SYMBOL_GPL(vsock_remove_pending);
+
+void vsock_pending_to_accept(struct sock *listener, struct sock *pending)
+{
+	struct vsock_sock *vpending = vsock_sk(pending);
+	struct vsock_sock *vlistener = vsock_sk(listener);
+
+	list_del_init(&vpending->pending_links);
+	list_add_tail(&vpending->accept_queue, &vlistener->accept_queue);
+}
+EXPORT_SYMBOL_GPL(vsock_pending_to_accept);
+
+void vsock_enqueue_accept(struct sock *listener, struct sock *connected)
+{
+	struct vsock_sock *vlistener;
+	struct vsock_sock *vconnected;
+
+	vlistener = vsock_sk(listener);
+	vconnected = vsock_sk(connected);
+
+	sock_hold(connected);
+	sock_hold(listener);
+	list_add_tail(&vconnected->accept_queue, &vlistener->accept_queue);
+	sk_acceptq_added(listener);
+}
+EXPORT_SYMBOL_GPL(vsock_enqueue_accept);
+
+static bool vsock_use_local_transport(unsigned int remote_cid)
+{
+	lockdep_assert_held(&vsock_register_mutex);
+
+	if (!transport_local)
+		return false;
+
+	if (remote_cid == VMADDR_CID_LOCAL)
+		return true;
+
+	if (transport_g2h) {
+		return remote_cid == transport_g2h->get_local_cid();
+	} else {
+		return remote_cid == VMADDR_CID_HOST;
+	}
+}
+
+static void vsock_deassign_transport(struct vsock_sock *vsk)
+{
+	if (!vsk->transport)
+		return;
+
+	vsk->transport->destruct(vsk);
+	module_put(vsk->transport->module);
+	vsk->transport = NULL;
+}
+
+/* Assign a transport to a socket and call the .init transport callback.
+ *
+ * Note: for connection oriented socket this must be called when vsk->remote_addr
+ * is set (e.g. during the connect() or when a connection request on a listener
+ * socket is received).
+ * The vsk->remote_addr is used to decide which transport to use:
+ *  - remote CID == VMADDR_CID_LOCAL or g2h->local_cid or VMADDR_CID_HOST if
+ *    g2h is not loaded, will use local transport;
+ *  - remote CID <= VMADDR_CID_HOST or remote flags field includes
+ *    VMADDR_FLAG_TO_HOST, will use guest->host transport;
+ *  - remote CID > VMADDR_CID_HOST and h2g is loaded and h2g claims that CID,
+ *    will use host->guest transport;
+ *  - h2g not loaded or h2g does not claim that CID and g2h claims the CID via
+ *    has_remote_cid, will use guest->host transport (when g2h_fallback=1)
+ *  - anything else goes to h2g or returns -ENODEV if no h2g is available
+ */
+int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
+{
+	const struct vsock_transport *new_transport;
+	struct sock *sk = sk_vsock(vsk);
+	unsigned int remote_cid = vsk->remote_addr.svm_cid;
+	__u8 remote_flags;
+	int ret;
+
+	/* If the packet is coming with the source and destination CIDs higher
+	 * than VMADDR_CID_HOST, then a vsock channel where all the packets are
+	 * forwarded to the host should be established. Then the host will
+	 * need to forward the packets to the guest.
+	 *
+	 * The flag is set on the (listen) receive path (psk is not NULL). On
+	 * the connect path the flag can be set by the user space application.
+	 */
+	if (psk && vsk->local_addr.svm_cid > VMADDR_CID_HOST &&
+	    vsk->remote_addr.svm_cid > VMADDR_CID_HOST)
+		vsk->remote_addr.svm_flags |= VMADDR_FLAG_TO_HOST;
+
+	remote_flags = vsk->remote_addr.svm_flags;
+
+	mutex_lock(&vsock_register_mutex);
+
+	switch (sk->sk_type) {
+	case SOCK_DGRAM:
+		new_transport = transport_dgram;
+		break;
+	case SOCK_STREAM:
+	case SOCK_SEQPACKET:
+		if (vsock_use_local_transport(remote_cid))
+			new_transport = transport_local;
+		else if (remote_cid <= VMADDR_CID_HOST ||
+			 (remote_flags & VMADDR_FLAG_TO_HOST))
+			new_transport = transport_g2h;
+		else if (transport_h2g &&
+			 (!transport_h2g->has_remote_cid ||
+			  transport_h2g->has_remote_cid(vsk, remote_cid)))
+			new_transport = transport_h2g;
+		else if (sock_net(sk)->vsock.g2h_fallback &&
+			 transport_g2h && transport_g2h->has_remote_cid &&
+			 transport_g2h->has_remote_cid(vsk, remote_cid)) {
+			vsk->remote_addr.svm_flags |= VMADDR_FLAG_TO_HOST;
+			new_transport = transport_g2h;
+		} else {
+			new_transport = transport_h2g;
+		}
+		break;
+	default:
+		ret = -ESOCKTNOSUPPORT;
+		goto err;
+	}
+
+	if (vsk->transport && vsk->transport == new_transport) {
+		ret = 0;
+		goto err;
+	}
+
+	/* We increase the module refcnt to prevent the transport unloading
+	 * while there are open sockets assigned to it.
+	 */
+	if (!new_transport || !try_module_get(new_transport->module)) {
+		ret = -ENODEV;
+		goto err;
+	}
+
+	/* It's safe to release the mutex after a successful try_module_get().
+	 * Whichever transport `new_transport` points at, it won't go away until
+	 * the last module_put() below or in vsock_deassign_transport().
+	 */
+	mutex_unlock(&vsock_register_mutex);
+
+	if (vsk->transport) {
+		/* transport->release() must be called with sock lock acquired.
+		 * This path can only be taken during vsock_connect(), where we
+		 * have already held the sock lock. In the other cases, this
+		 * function is called on a new socket which is not assigned to
+		 * any transport.
+		 */
+		vsk->transport->release(vsk);
+		vsock_deassign_transport(vsk);
+
+		/* transport's release() and destruct() can touch some socket
+		 * state, since we are reassigning the socket to a new transport
+		 * during vsock_connect(), let's reset these fields to have a
+		 * clean state.
+		 */
+		sock_reset_flag(sk, SOCK_DONE);
+		sk->sk_state = TCP_CLOSE;
+		WRITE_ONCE(vsk->peer_shutdown, 0);
+	}
+
+	if (sk->sk_type == SOCK_SEQPACKET) {
+		if (!new_transport->seqpacket_allow ||
+		    !new_transport->seqpacket_allow(vsk, remote_cid)) {
+			module_put(new_transport->module);
+			return -ESOCKTNOSUPPORT;
+		}
+	}
+
+	ret = new_transport->init(vsk, psk);
+	if (ret) {
+		module_put(new_transport->module);
+		return ret;
+	}
+
+	vsk->transport = new_transport;
+
+	return 0;
+err:
+	mutex_unlock(&vsock_register_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vsock_assign_transport);
+
+/*
+ * Provide safe access to static transport_{h2g,g2h,dgram,local} callbacks.
+ * Otherwise we may race with module removal. Do not use on `vsk->transport`.
+ */
+static u32 vsock_registered_transport_cid(const struct vsock_transport **transport)
+{
+	u32 cid = VMADDR_CID_ANY;
+
+	mutex_lock(&vsock_register_mutex);
+	if (*transport)
+		cid = (*transport)->get_local_cid();
+	mutex_unlock(&vsock_register_mutex);
+
+	return cid;
+}
+
+bool vsock_find_cid(unsigned int cid)
+{
+	if (cid == vsock_registered_transport_cid(&transport_g2h))
+		return true;
+
+	if (transport_h2g && cid == VMADDR_CID_HOST)
+		return true;
+
+	if (transport_local && cid == VMADDR_CID_LOCAL)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(vsock_find_cid);
+
+static struct sock *vsock_dequeue_accept(struct sock *listener)
+{
+	struct vsock_sock *vlistener;
+	struct vsock_sock *vconnected;
+
+	vlistener = vsock_sk(listener);
+
+	if (list_empty(&vlistener->accept_queue))
+		return NULL;
+
+	vconnected = list_entry(vlistener->accept_queue.next,
+				struct vsock_sock, accept_queue);
+
+	list_del_init(&vconnected->accept_queue);
+	sock_put(listener);
+	/* The caller will need a reference on the connected socket so we let
+	 * it call sock_put().
+	 */
+
+	return sk_vsock(vconnected);
+}
+
+static bool vsock_is_accept_queue_empty(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+	return list_empty(&vsk->accept_queue);
+}
+
+static bool vsock_is_pending(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+	return !list_empty(&vsk->pending_links);
+}
+
+static int vsock_send_shutdown(struct sock *sk, int mode)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (!vsk->transport)
+		return -ENODEV;
+
+	return vsk->transport->shutdown(vsk, mode);
+}
+
+static void vsock_pending_work(struct work_struct *work)
+{
+	struct sock *sk;
+	struct sock *listener;
+	struct vsock_sock *vsk;
+	bool cleanup;
+
+	vsk = container_of(work, struct vsock_sock, pending_work.work);
+	sk = sk_vsock(vsk);
+	listener = vsk->listener;
+	cleanup = true;
+
+	lock_sock(listener);
+	lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+
+	if (vsock_is_pending(sk)) {
+		vsock_remove_pending(listener, sk);
+	} else {
+		/* We are not on the pending list so we must have been accepted
+		 * by our user process. We just need to drop our references to
+		 * the sockets and be on our way.
+		 */
+		cleanup = false;
+		goto out;
+	}
+
+	/* We need to remove ourself from the global connected sockets list so
+	 * incoming packets can't find this socket, and to reduce the reference
+	 * count.
+	 */
+	vsock_remove_connected(vsk);
+
+	sk->sk_state = TCP_CLOSE;
+
+out:
+	release_sock(sk);
+	release_sock(listener);
+	if (cleanup)
+		sock_put(sk);
+
+	sock_put(sk);
+	sock_put(listener);
+}
+
+/**** SOCKET OPERATIONS ****/
+
+static int __vsock_bind_connectible(struct vsock_sock *vsk,
+				    struct sockaddr_vm *addr)
+{
+	struct net *net = sock_net(sk_vsock(vsk));
+	struct sockaddr_vm new_addr;
+
+	if (!net->vsock.port)
+		net->vsock.port = get_random_u32_above(LAST_RESERVED_PORT);
+
+	vsock_addr_init(&new_addr, addr->svm_cid, addr->svm_port);
+
+	if (addr->svm_port == VMADDR_PORT_ANY) {
+		bool found = false;
+		unsigned int i;
+
+		for (i = 0; i < MAX_PORT_RETRIES; i++) {
+			if (net->vsock.port == VMADDR_PORT_ANY ||
+			    net->vsock.port <= LAST_RESERVED_PORT)
+				net->vsock.port = LAST_RESERVED_PORT + 1;
+
+			new_addr.svm_port = net->vsock.port++;
+
+			if (!__vsock_find_bound_socket_net(&new_addr, net)) {
+				found = true;
+				break;
+			}
+		}
+
+		if (!found)
+			return -EADDRNOTAVAIL;
+	} else {
+		/* If port is in reserved range, ensure caller
+		 * has necessary privileges.
+		 */
+		if (addr->svm_port <= LAST_RESERVED_PORT &&
+		    !capable(CAP_NET_BIND_SERVICE)) {
+			return -EACCES;
+		}
+
+		if (__vsock_find_bound_socket_net(&new_addr, net))
+			return -EADDRINUSE;
+	}
+
+	vsock_addr_init(&vsk->local_addr, new_addr.svm_cid, new_addr.svm_port);
+
+	/* Remove connection oriented sockets from the unbound list and add them
+	 * to the hash table for easy lookup by its address.  The unbound list
+	 * is simply an extra entry at the end of the hash table, a trick used
+	 * by AF_UNIX.
+	 */
+	__vsock_remove_bound(vsk);
+	__vsock_insert_bound(vsock_bound_sockets(&vsk->local_addr), vsk);
+
+	return 0;
+}
+
+static int __vsock_bind_dgram(struct vsock_sock *vsk,
+			      struct sockaddr_vm *addr)
+{
+	return vsk->transport->dgram_bind(vsk, addr);
+}
+
+static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+	int retval;
+
+	/* First ensure this socket isn't already bound. */
+	if (vsock_addr_bound(&vsk->local_addr))
+		return -EINVAL;
+
+	/* Now bind to the provided address or select appropriate values if
+	 * none are provided (VMADDR_CID_ANY and VMADDR_PORT_ANY).  Note that
+	 * like AF_INET prevents binding to a non-local IP address (in most
+	 * cases), we only allow binding to a local CID.
+	 */
+	if (addr->svm_cid != VMADDR_CID_ANY && !vsock_find_cid(addr->svm_cid))
+		return -EADDRNOTAVAIL;
+
+	switch (sk->sk_socket->type) {
+	case SOCK_STREAM:
+	case SOCK_SEQPACKET:
+		spin_lock_bh(&vsock_table_lock);
+		retval = __vsock_bind_connectible(vsk, addr);
+		spin_unlock_bh(&vsock_table_lock);
+		break;
+
+	case SOCK_DGRAM:
+		retval = __vsock_bind_dgram(vsk, addr);
+		break;
+
+	default:
+		retval = -EINVAL;
+		break;
+	}
+
+	return retval;
+}
+
+static void vsock_connect_timeout(struct work_struct *work);
+
+static struct sock *__vsock_create(struct net *net,
+				   struct socket *sock,
+				   struct sock *parent,
+				   gfp_t priority,
+				   unsigned short type,
+				   int kern)
+{
+	struct sock *sk;
+	struct vsock_sock *psk;
+	struct vsock_sock *vsk;
+
+	sk = sk_alloc(net, AF_VSOCK, priority, &vsock_proto, kern);
+	if (!sk)
+		return NULL;
+
+	sock_init_data(sock, sk);
+
+	/* sk->sk_type is normally set in sock_init_data, but only if sock is
+	 * non-NULL. We make sure that our sockets always have a type by
+	 * setting it here if needed.
+	 */
+	if (!sock)
+		sk->sk_type = type;
+
+	vsk = vsock_sk(sk);
+	vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
+	vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
+
+	sk->sk_destruct = vsock_sk_destruct;
+	sk->sk_backlog_rcv = vsock_queue_rcv_skb;
+	sock_reset_flag(sk, SOCK_DONE);
+
+	INIT_LIST_HEAD(&vsk->bound_table);
+	INIT_LIST_HEAD(&vsk->connected_table);
+	vsk->listener = NULL;
+	INIT_LIST_HEAD(&vsk->pending_links);
+	INIT_LIST_HEAD(&vsk->accept_queue);
+	vsk->sent_request = false;
+	vsk->ignore_connecting_rst = false;
+	WRITE_ONCE(vsk->peer_shutdown, 0);
+	INIT_DELAYED_WORK(&vsk->connect_work, vsock_connect_timeout);
+	INIT_DELAYED_WORK(&vsk->pending_work, vsock_pending_work);
+
+	psk = parent ? vsock_sk(parent) : NULL;
+	if (parent) {
+		vsk->trusted = psk->trusted;
+		vsk->owner = get_cred(psk->owner);
+		vsk->connect_timeout = psk->connect_timeout;
+		vsk->buffer_size = psk->buffer_size;
+		vsk->buffer_min_size = psk->buffer_min_size;
+		vsk->buffer_max_size = psk->buffer_max_size;
+		security_sk_clone(parent, sk);
+	} else {
+		vsk->trusted = ns_capable_noaudit(&init_user_ns, CAP_NET_ADMIN);
+		vsk->owner = get_current_cred();
+		vsk->connect_timeout = VSOCK_DEFAULT_CONNECT_TIMEOUT;
+		vsk->buffer_size = VSOCK_DEFAULT_BUFFER_SIZE;
+		vsk->buffer_min_size = VSOCK_DEFAULT_BUFFER_MIN_SIZE;
+		vsk->buffer_max_size = VSOCK_DEFAULT_BUFFER_MAX_SIZE;
+	}
+
+	return sk;
+}
+
+static bool sock_type_connectible(u16 type)
+{
+	return (type == SOCK_STREAM) || (type == SOCK_SEQPACKET);
+}
+
+static void __vsock_release(struct sock *sk, int level)
+{
+	struct vsock_sock *vsk;
+	struct sock *pending;
+
+	vsk = vsock_sk(sk);
+	pending = NULL;	/* Compiler warning. */
+
+	/* When "level" is SINGLE_DEPTH_NESTING, use the nested
+	 * version to avoid the warning "possible recursive locking
+	 * detected". When "level" is 0, lock_sock_nested(sk, level)
+	 * is the same as lock_sock(sk).
+	 */
+	lock_sock_nested(sk, level);
+
+	/* Indicate to vsock_remove_sock() that the socket is being released and
+	 * can be removed from the bound_table. Unlike transport reassignment
+	 * case, where the socket must remain bound despite vsock_remove_sock()
+	 * being called from the transport release() callback.
+	 */
+	sock_set_flag(sk, SOCK_DEAD);
+
+	if (vsk->transport)
+		vsk->transport->release(vsk);
+	else if (sock_type_connectible(sk->sk_type))
+		vsock_remove_sock(vsk);
+
+	sock_orphan(sk);
+	sk->sk_shutdown = SHUTDOWN_MASK;
+
+	skb_queue_purge(&sk->sk_receive_queue);
+
+	/* Clean up any sockets that never were accepted. */
+	while ((pending = vsock_dequeue_accept(sk)) != NULL) {
+		__vsock_release(pending, SINGLE_DEPTH_NESTING);
+		sock_put(pending);
+	}
+
+	release_sock(sk);
+	sock_put(sk);
+}
+
+static void vsock_sk_destruct(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	/* Flush MSG_ZEROCOPY leftovers. */
+	__skb_queue_purge(&sk->sk_error_queue);
+
+	vsock_deassign_transport(vsk);
+
+	/* When clearing these addresses, there's no need to set the family and
+	 * possibly register the address family with the kernel.
+	 */
+	vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
+	vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
+
+	put_cred(vsk->owner);
+}
+
+static int vsock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	int err;
+
+	err = sock_queue_rcv_skb(sk, skb);
+	if (err)
+		kfree_skb(skb);
+
+	return err;
+}
+
+struct sock *vsock_create_connected(struct sock *parent)
+{
+	return __vsock_create(sock_net(parent), NULL, parent, GFP_KERNEL,
+			      parent->sk_type, 0);
+}
+EXPORT_SYMBOL_GPL(vsock_create_connected);
+
+s64 vsock_stream_has_data(struct vsock_sock *vsk)
+{
+	if (WARN_ON(!vsk->transport))
+		return 0;
+
+	return vsk->transport->stream_has_data(vsk);
+}
+EXPORT_SYMBOL_GPL(vsock_stream_has_data);
+
+s64 vsock_connectible_has_data(struct vsock_sock *vsk)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	if (WARN_ON(!vsk->transport))
+		return 0;
+
+	if (sk->sk_type == SOCK_SEQPACKET)
+		return vsk->transport->seqpacket_has_data(vsk);
+	else
+		return vsock_stream_has_data(vsk);
+}
+EXPORT_SYMBOL_GPL(vsock_connectible_has_data);
+
+s64 vsock_stream_has_space(struct vsock_sock *vsk)
+{
+	if (WARN_ON(!vsk->transport))
+		return 0;
+
+	return vsk->transport->stream_has_space(vsk);
+}
+EXPORT_SYMBOL_GPL(vsock_stream_has_space);
+
+void vsock_data_ready(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (vsock_stream_has_data(vsk) >= sk->sk_rcvlowat ||
+	    sock_flag(sk, SOCK_DONE))
+		sk->sk_data_ready(sk);
+}
+EXPORT_SYMBOL_GPL(vsock_data_ready);
+
+/* Dummy callback required by sockmap.
+ * See unconditional call of saved_close() in sock_map_close().
+ */
+static void vsock_close(struct sock *sk, long timeout)
+{
+}
+
+static int vsock_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+
+	if (!sk)
+		return 0;
+
+	sk->sk_prot->close(sk, 0);
+	__vsock_release(sk, 0);
+	sock->sk = NULL;
+	sock->state = SS_FREE;
+
+	return 0;
+}
+
+static int
+vsock_bind(struct socket *sock, struct sockaddr_unsized *addr, int addr_len)
+{
+	int err;
+	struct sock *sk;
+	struct sockaddr_vm *vm_addr;
+
+	sk = sock->sk;
+
+	if (vsock_addr_cast(addr, addr_len, &vm_addr) != 0)
+		return -EINVAL;
+
+	lock_sock(sk);
+	err = __vsock_bind(sk, vm_addr);
+	release_sock(sk);
+
+	return err;
+}
+
+static int vsock_getname(struct socket *sock,
+			 struct sockaddr *addr, int peer)
+{
+	int err;
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	struct sockaddr_vm *vm_addr;
+
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+	err = 0;
+
+	lock_sock(sk);
+
+	if (peer) {
+		if (sock->state != SS_CONNECTED) {
+			err = -ENOTCONN;
+			goto out;
+		}
+		vm_addr = &vsk->remote_addr;
+	} else {
+		vm_addr = &vsk->local_addr;
+	}
+
+	BUILD_BUG_ON(sizeof(*vm_addr) > sizeof(struct sockaddr_storage));
+	memcpy(addr, vm_addr, sizeof(*vm_addr));
+	err = sizeof(*vm_addr);
+
+out:
+	release_sock(sk);
+	return err;
+}
+
+void vsock_linger(struct sock *sk)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	ssize_t (*unsent)(struct vsock_sock *vsk);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	long timeout;
+
+	if (!sock_flag(sk, SOCK_LINGER))
+		return;
+
+	timeout = sk->sk_lingertime;
+	if (!timeout)
+		return;
+
+	/* Transports must implement `unsent_bytes` if they want to support
+	 * SOCK_LINGER through `vsock_linger()` since we use it to check when
+	 * the socket can be closed.
+	 */
+	unsent = vsk->transport->unsent_bytes;
+	if (!unsent)
+		return;
+
+	add_wait_queue(sk_sleep(sk), &wait);
+
+	do {
+		if (sk_wait_event(sk, &timeout, unsent(vsk) == 0, &wait))
+			break;
+	} while (!signal_pending(current) && timeout);
+
+	remove_wait_queue(sk_sleep(sk), &wait);
+}
+EXPORT_SYMBOL_GPL(vsock_linger);
+
+static int vsock_shutdown(struct socket *sock, int mode)
+{
+	int err;
+	struct sock *sk;
+
+	/* User level uses SHUT_RD (0) and SHUT_WR (1), but the kernel uses
+	 * RCV_SHUTDOWN (1) and SEND_SHUTDOWN (2), so we must increment mode
+	 * here like the other address families do.  Note also that the
+	 * increment makes SHUT_RDWR (2) into RCV_SHUTDOWN | SEND_SHUTDOWN (3),
+	 * which is what we want.
+	 */
+	mode++;
+
+	if ((mode & ~SHUTDOWN_MASK) || !mode)
+		return -EINVAL;
+
+	/* If this is a connection oriented socket and it is not connected then
+	 * bail out immediately.  If it is a DGRAM socket then we must first
+	 * kick the socket so that it wakes up from any sleeping calls, for
+	 * example recv(), and then afterwards return the error.
+	 */
+
+	sk = sock->sk;
+
+	lock_sock(sk);
+	if (sock->state == SS_UNCONNECTED) {
+		err = -ENOTCONN;
+		if (sock_type_connectible(sk->sk_type))
+			goto out;
+	} else {
+		sock->state = SS_DISCONNECTING;
+		err = 0;
+	}
+
+	/* Receive and send shutdowns are treated alike. */
+	mode = mode & (RCV_SHUTDOWN | SEND_SHUTDOWN);
+	if (mode) {
+		sk->sk_shutdown |= mode;
+		sk->sk_state_change(sk);
+
+		if (sock_type_connectible(sk->sk_type)) {
+			sock_reset_flag(sk, SOCK_DONE);
+			vsock_send_shutdown(sk, mode);
+		}
+	}
+
+out:
+	release_sock(sk);
+	return err;
+}
+
+static __poll_t vsock_poll_shutdown(struct sock *sk, u32 peer_shutdown)
+{
+	__poll_t mask = 0;
+
+	/* INET sockets treat local write shutdown and peer write shutdown as a
+	 * case of EPOLLHUP set.
+	 */
+	if (sk->sk_shutdown == SHUTDOWN_MASK ||
+	    ((sk->sk_shutdown & SEND_SHUTDOWN) &&
+	     (peer_shutdown & SEND_SHUTDOWN)))
+		mask |= EPOLLHUP;
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN ||
+	    peer_shutdown & SEND_SHUTDOWN)
+		mask |= EPOLLRDHUP;
+
+	return mask;
+}
+
+static __poll_t vsock_poll(struct file *file, struct socket *sock,
+			       poll_table *wait)
+{
+	struct sock *sk;
+	__poll_t mask;
+	struct vsock_sock *vsk;
+
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+
+	poll_wait(file, sk_sleep(sk), wait);
+	mask = 0;
+
+	if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
+		/* Signify that there has been an error on this socket. */
+		mask |= EPOLLERR;
+
+	if (sk_is_readable(sk))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	if (sock->type == SOCK_DGRAM) {
+		u32 peer_shutdown = READ_ONCE(vsk->peer_shutdown);
+
+		/* DGRAM sockets do not take lock_sock() in poll(), so use one
+		 * lockless snapshot for all shutdown-derived mask bits.
+		 */
+		mask |= vsock_poll_shutdown(sk, peer_shutdown);
+
+		/* For datagram sockets we can read if there is something in
+		 * the queue and write as long as the socket isn't shutdown for
+		 * sending.
+		 */
+		if (!skb_queue_empty_lockless(&sk->sk_receive_queue) ||
+		    (sk->sk_shutdown & RCV_SHUTDOWN)) {
+			mask |= EPOLLIN | EPOLLRDNORM;
+		}
+
+		if (!(sk->sk_shutdown & SEND_SHUTDOWN))
+			mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
+
+	} else if (sock_type_connectible(sk->sk_type)) {
+		const struct vsock_transport *transport;
+		u32 peer_shutdown;
+
+		lock_sock(sk);
+
+		transport = vsk->transport;
+
+		/* Listening sockets that have connections in their accept
+		 * queue can be read.
+		 */
+		if (sk->sk_state == TCP_LISTEN
+		    && !vsock_is_accept_queue_empty(sk))
+			mask |= EPOLLIN | EPOLLRDNORM;
+
+		/* If there is something in the queue then we can read. */
+		if (transport && transport->stream_is_active(vsk) &&
+		    !(sk->sk_shutdown & RCV_SHUTDOWN)) {
+			bool data_ready_now = false;
+			int target = sock_rcvlowat(sk, 0, INT_MAX);
+			int ret = transport->notify_poll_in(
+					vsk, target, &data_ready_now);
+			if (ret < 0) {
+				mask |= EPOLLERR;
+			} else {
+				if (data_ready_now)
+					mask |= EPOLLIN | EPOLLRDNORM;
+
+			}
+		}
+
+		/* Sockets whose connections have been closed, reset, or
+		 * terminated should also be considered read, and we check the
+		 * shutdown flag for that.
+		 */
+		peer_shutdown = READ_ONCE(vsk->peer_shutdown);
+		mask |= vsock_poll_shutdown(sk, peer_shutdown);
+		if (sk->sk_shutdown & RCV_SHUTDOWN ||
+		    peer_shutdown & SEND_SHUTDOWN) {
+			mask |= EPOLLIN | EPOLLRDNORM;
+		}
+
+		/* Connected sockets that can produce data can be written. */
+		if (transport && sk->sk_state == TCP_ESTABLISHED) {
+			if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
+				bool space_avail_now = false;
+				int ret = transport->notify_poll_out(
+						vsk, 1, &space_avail_now);
+				if (ret < 0) {
+					mask |= EPOLLERR;
+				} else {
+					if (space_avail_now)
+						/* Remove EPOLLWRBAND since INET
+						 * sockets are not setting it.
+						 */
+						mask |= EPOLLOUT | EPOLLWRNORM;
+
+				}
+			}
+		}
+
+		/* Simulate INET socket poll behaviors, which sets
+		 * EPOLLOUT|EPOLLWRNORM when peer is closed and nothing to read,
+		 * but local send is not shutdown.
+		 */
+		if (sk->sk_state == TCP_CLOSE || sk->sk_state == TCP_CLOSING) {
+			if (!(sk->sk_shutdown & SEND_SHUTDOWN))
+				mask |= EPOLLOUT | EPOLLWRNORM;
+
+		}
+
+		release_sock(sk);
+	}
+
+	return mask;
+}
+
+static int vsock_read_skb(struct sock *sk, skb_read_actor_t read_actor)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (WARN_ON_ONCE(!vsk->transport))
+		return -ENODEV;
+
+	return vsk->transport->read_skb(vsk, read_actor);
+}
+
+static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
+			       size_t len)
+{
+	int err;
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	struct sockaddr_vm *remote_addr;
+	const struct vsock_transport *transport;
+
+	if (msg->msg_flags & MSG_OOB)
+		return -EOPNOTSUPP;
+
+	/* For now, MSG_DONTWAIT is always assumed... */
+	err = 0;
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+
+	lock_sock(sk);
+
+	transport = vsk->transport;
+
+	err = vsock_auto_bind(vsk);
+	if (err)
+		goto out;
+
+
+	/* If the provided message contains an address, use that.  Otherwise
+	 * fall back on the socket's remote handle (if it has been connected).
+	 */
+	if (msg->msg_name &&
+	    vsock_addr_cast(msg->msg_name, msg->msg_namelen,
+			    &remote_addr) == 0) {
+		/* Ensure this address is of the right type and is a valid
+		 * destination.
+		 */
+
+		if (remote_addr->svm_cid == VMADDR_CID_ANY)
+			remote_addr->svm_cid = transport->get_local_cid();
+
+		if (!vsock_addr_bound(remote_addr)) {
+			err = -EINVAL;
+			goto out;
+		}
+	} else if (sock->state == SS_CONNECTED) {
+		remote_addr = &vsk->remote_addr;
+
+		if (remote_addr->svm_cid == VMADDR_CID_ANY)
+			remote_addr->svm_cid = transport->get_local_cid();
+
+		/* XXX Should connect() or this function ensure remote_addr is
+		 * bound?
+		 */
+		if (!vsock_addr_bound(&vsk->remote_addr)) {
+			err = -EINVAL;
+			goto out;
+		}
+	} else {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (!transport->dgram_allow(vsk, remote_addr->svm_cid,
+				    remote_addr->svm_port)) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	err = transport->dgram_enqueue(vsk, remote_addr, msg, len);
+
+out:
+	release_sock(sk);
+	return err;
+}
+
+static int vsock_dgram_connect(struct socket *sock,
+			       struct sockaddr_unsized *addr, int addr_len, int flags)
+{
+	int err;
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	struct sockaddr_vm *remote_addr;
+
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+
+	err = vsock_addr_cast(addr, addr_len, &remote_addr);
+	if (err == -EAFNOSUPPORT && remote_addr->svm_family == AF_UNSPEC) {
+		lock_sock(sk);
+		vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY,
+				VMADDR_PORT_ANY);
+		sock->state = SS_UNCONNECTED;
+		release_sock(sk);
+		return 0;
+	} else if (err != 0)
+		return -EINVAL;
+
+	lock_sock(sk);
+
+	err = vsock_auto_bind(vsk);
+	if (err)
+		goto out;
+
+	if (!vsk->transport->dgram_allow(vsk, remote_addr->svm_cid,
+					 remote_addr->svm_port)) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	memcpy(&vsk->remote_addr, remote_addr, sizeof(vsk->remote_addr));
+	sock->state = SS_CONNECTED;
+
+	/* sock map disallows redirection of non-TCP sockets with sk_state !=
+	 * TCP_ESTABLISHED (see sock_map_redirect_allowed()), so we set
+	 * TCP_ESTABLISHED here to allow redirection of connected vsock dgrams.
+	 *
+	 * This doesn't seem to be abnormal state for datagram sockets, as the
+	 * same approach can be see in other datagram socket types as well
+	 * (such as unix sockets).
+	 */
+	sk->sk_state = TCP_ESTABLISHED;
+
+out:
+	release_sock(sk);
+	return err;
+}
+
+int __vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
+			  size_t len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
+}
+
+int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
+			size_t len, int flags)
+{
+#ifdef CONFIG_BPF_SYSCALL
+	struct sock *sk = sock->sk;
+	const struct proto *prot;
+
+	prot = READ_ONCE(sk->sk_prot);
+	if (prot != &vsock_proto)
+		return prot->recvmsg(sk, msg, len, flags);
+#endif
+
+	return __vsock_dgram_recvmsg(sock, msg, len, flags);
+}
+EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
+
+static int vsock_do_ioctl(struct socket *sock, unsigned int cmd,
+			  int __user *arg)
+{
+	struct sock *sk = sock->sk;
+	struct vsock_sock *vsk;
+	int ret;
+
+	vsk = vsock_sk(sk);
+
+	switch (cmd) {
+	case SIOCINQ: {
+		ssize_t n_bytes;
+
+		if (!vsk->transport) {
+			ret = -EOPNOTSUPP;
+			break;
+		}
+
+		if (sock_type_connectible(sk->sk_type) &&
+		    sk->sk_state == TCP_LISTEN) {
+			ret = -EINVAL;
+			break;
+		}
+
+		n_bytes = vsock_stream_has_data(vsk);
+		if (n_bytes < 0) {
+			ret = n_bytes;
+			break;
+		}
+		ret = put_user(n_bytes, arg);
+		break;
+	}
+	case SIOCOUTQ: {
+		ssize_t n_bytes;
+
+		if (!vsk->transport || !vsk->transport->unsent_bytes) {
+			ret = -EOPNOTSUPP;
+			break;
+		}
+
+		if (sock_type_connectible(sk->sk_type) && sk->sk_state == TCP_LISTEN) {
+			ret = -EINVAL;
+			break;
+		}
+
+		n_bytes = vsk->transport->unsent_bytes(vsk);
+		if (n_bytes < 0) {
+			ret = n_bytes;
+			break;
+		}
+
+		ret = put_user(n_bytes, arg);
+		break;
+	}
+	default:
+		ret = -ENOIOCTLCMD;
+	}
+
+	return ret;
+}
+
+static int vsock_ioctl(struct socket *sock, unsigned int cmd,
+		       unsigned long arg)
+{
+	int ret;
+
+	lock_sock(sock->sk);
+	ret = vsock_do_ioctl(sock, cmd, (int __user *)arg);
+	release_sock(sock->sk);
+
+	return ret;
+}
+
+static const struct proto_ops vsock_dgram_ops = {
+	.family = PF_VSOCK,
+	.owner = THIS_MODULE,
+	.release = vsock_release,
+	.bind = vsock_bind,
+	.connect = vsock_dgram_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = sock_no_accept,
+	.getname = vsock_getname,
+	.poll = vsock_poll,
+	.ioctl = vsock_ioctl,
+	.listen = sock_no_listen,
+	.shutdown = vsock_shutdown,
+	.sendmsg = vsock_dgram_sendmsg,
+	.recvmsg = vsock_dgram_recvmsg,
+	.mmap = sock_no_mmap,
+	.read_skb = vsock_read_skb,
+};
+
+static int vsock_transport_cancel_pkt(struct vsock_sock *vsk)
+{
+	const struct vsock_transport *transport = vsk->transport;
+
+	if (!transport || !transport->cancel_pkt)
+		return -EOPNOTSUPP;
+
+	return transport->cancel_pkt(vsk);
+}
+
+static void vsock_connect_timeout(struct work_struct *work)
+{
+	struct sock *sk;
+	struct vsock_sock *vsk;
+
+	vsk = container_of(work, struct vsock_sock, connect_work.work);
+	sk = sk_vsock(vsk);
+
+	lock_sock(sk);
+	if (sk->sk_state == TCP_SYN_SENT &&
+	    (sk->sk_shutdown != SHUTDOWN_MASK)) {
+		sk->sk_state = TCP_CLOSE;
+		sk->sk_socket->state = SS_UNCONNECTED;
+		sk->sk_err = ETIMEDOUT;
+		sk_error_report(sk);
+		vsock_transport_cancel_pkt(vsk);
+	}
+	release_sock(sk);
+
+	sock_put(sk);
+}
+
+static int vsock_connect(struct socket *sock, struct sockaddr_unsized *addr,
+			 int addr_len, int flags)
+{
+	int err;
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	const struct vsock_transport *transport;
+	struct sockaddr_vm *remote_addr;
+	long timeout;
+	DEFINE_WAIT(wait);
+
+	err = 0;
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+
+	lock_sock(sk);
+
+	/* XXX AF_UNSPEC should make us disconnect like AF_INET. */
+	switch (sock->state) {
+	case SS_CONNECTED:
+		err = -EISCONN;
+		goto out;
+	case SS_DISCONNECTING:
+		err = -EINVAL;
+		goto out;
+	case SS_CONNECTING:
+		/* This continues on so we can move sock into the SS_CONNECTED
+		 * state once the connection has completed (at which point err
+		 * will be set to zero also).  Otherwise, we will either wait
+		 * for the connection or return -EALREADY should this be a
+		 * non-blocking call.
+		 */
+		err = -EALREADY;
+		if (flags & O_NONBLOCK)
+			goto out;
+		break;
+	default:
+		if ((sk->sk_state == TCP_LISTEN) ||
+		    vsock_addr_cast(addr, addr_len, &remote_addr) != 0) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		/* Set the remote address that we are connecting to. */
+		memcpy(&vsk->remote_addr, remote_addr,
+		       sizeof(vsk->remote_addr));
+
+		err = vsock_assign_transport(vsk, NULL);
+		if (err)
+			goto out;
+
+		transport = vsk->transport;
+
+		/* The hypervisor and well-known contexts do not have socket
+		 * endpoints.
+		 */
+		if (!transport ||
+		    !transport->stream_allow(vsk, remote_addr->svm_cid,
+					     remote_addr->svm_port)) {
+			err = -ENETUNREACH;
+			goto out;
+		}
+
+		if (vsock_msgzerocopy_allow(transport)) {
+			set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
+		} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
+			/* If this option was set before 'connect()',
+			 * when transport was unknown, check that this
+			 * feature is supported here.
+			 */
+			err = -EOPNOTSUPP;
+			goto out;
+		}
+
+		err = vsock_auto_bind(vsk);
+		if (err)
+			goto out;
+
+		sk->sk_state = TCP_SYN_SENT;
+
+		err = transport->connect(vsk);
+		if (err < 0)
+			goto out;
+
+		/* sk_err might have been set as a result of an earlier
+		 * (failed) connect attempt.
+		 */
+		sk->sk_err = 0;
+
+		/* Mark sock as connecting and set the error code to in
+		 * progress in case this is a non-blocking connect.
+		 */
+		sock->state = SS_CONNECTING;
+		err = -EINPROGRESS;
+	}
+
+	/* The receive path will handle all communication until we are able to
+	 * enter the connected state.  Here we wait for the connection to be
+	 * completed or a notification of an error.
+	 */
+	timeout = vsk->connect_timeout;
+	prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+
+	/* If the socket is already closing or it is in an error state, there
+	 * is no point in waiting.
+	 */
+	while (sk->sk_state != TCP_ESTABLISHED &&
+	       sk->sk_state != TCP_CLOSING && sk->sk_err == 0) {
+		if (flags & O_NONBLOCK) {
+			/* If we're not going to block, we schedule a timeout
+			 * function to generate a timeout on the connection
+			 * attempt, in case the peer doesn't respond in a
+			 * timely manner. We hold on to the socket until the
+			 * timeout fires.
+			 */
+			sock_hold(sk);
+
+			/* If the timeout function is already scheduled,
+			 * reschedule it, then ungrab the socket refcount to
+			 * keep it balanced.
+			 */
+			if (mod_delayed_work(system_percpu_wq, &vsk->connect_work,
+					     timeout))
+				sock_put(sk);
+
+			/* Skip ahead to preserve error code set above. */
+			goto out_wait;
+		}
+
+		release_sock(sk);
+		timeout = schedule_timeout(timeout);
+		lock_sock(sk);
+
+		/* Connection established. Whatever happens to socket once we
+		 * release it, that's not connect()'s concern. No need to go
+		 * into signal and timeout handling. Call it a day.
+		 *
+		 * Note that allowing to "reset" an already established socket
+		 * here is racy and insecure.
+		 */
+		if (sk->sk_state == TCP_ESTABLISHED)
+			break;
+
+		/* If connection was _not_ established and a signal/timeout came
+		 * to be, we want the socket's state reset. User space may want
+		 * to retry.
+		 *
+		 * sk_state != TCP_ESTABLISHED implies that socket is not on
+		 * vsock_connected_table. We keep the binding and the transport
+		 * assigned.
+		 */
+		if (signal_pending(current) || timeout == 0) {
+			err = timeout == 0 ? -ETIMEDOUT : sock_intr_errno(timeout);
+
+			/* Listener might have already responded with
+			 * VIRTIO_VSOCK_OP_RESPONSE. Its handling expects our
+			 * sk_state == TCP_SYN_SENT, which hereby we break.
+			 * In such case VIRTIO_VSOCK_OP_RST will follow.
+			 */
+			sk->sk_state = TCP_CLOSE;
+			sock->state = SS_UNCONNECTED;
+
+			/* Try to cancel VIRTIO_VSOCK_OP_REQUEST skb sent out by
+			 * transport->connect().
+			 */
+			vsock_transport_cancel_pkt(vsk);
+
+			goto out_wait;
+		}
+
+		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+	}
+
+	err = sock_error(sk);
+	if (err) {
+		sk->sk_state = TCP_CLOSE;
+		sock->state = SS_UNCONNECTED;
+	}
+
+out_wait:
+	finish_wait(sk_sleep(sk), &wait);
+out:
+	release_sock(sk);
+	return err;
+}
+
+static int vsock_accept(struct socket *sock, struct socket *newsock,
+			struct proto_accept_arg *arg)
+{
+	struct sock *listener;
+	int err;
+	struct sock *connected;
+	struct vsock_sock *vconnected;
+	long timeout;
+	DEFINE_WAIT(wait);
+
+	err = 0;
+	listener = sock->sk;
+
+	lock_sock(listener);
+
+	if (!sock_type_connectible(sock->type)) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (listener->sk_state != TCP_LISTEN) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* Wait for children sockets to appear; these are the new sockets
+	 * created upon connection establishment.
+	 */
+	timeout = sock_rcvtimeo(listener, arg->flags & O_NONBLOCK);
+
+	while ((connected = vsock_dequeue_accept(listener)) == NULL &&
+		timeout != 0) {
+		prepare_to_wait(sk_sleep(listener), &wait, TASK_INTERRUPTIBLE);
+		release_sock(listener);
+		timeout = schedule_timeout(timeout);
+		finish_wait(sk_sleep(listener), &wait);
+		lock_sock(listener);
+
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeout);
+			goto out;
+		}
+	}
+
+	if (!connected) {
+		err = -EAGAIN;
+	} else {
+		sk_acceptq_removed(listener);
+
+		lock_sock_nested(connected, SINGLE_DEPTH_NESTING);
+		vconnected = vsock_sk(connected);
+
+		newsock->state = SS_CONNECTED;
+		sock_graft(connected, newsock);
+
+		set_bit(SOCK_CUSTOM_SOCKOPT,
+			&connected->sk_socket->flags);
+
+		if (vsock_msgzerocopy_allow(vconnected->transport))
+			set_bit(SOCK_SUPPORT_ZC,
+				&connected->sk_socket->flags);
+
+		release_sock(connected);
+		sock_put(connected);
+	}
+
+out:
+	release_sock(listener);
+	return err;
+}
+
+static int vsock_listen(struct socket *sock, int backlog)
+{
+	int err;
+	struct sock *sk;
+	struct vsock_sock *vsk;
+
+	sk = sock->sk;
+
+	lock_sock(sk);
+
+	if (!sock_type_connectible(sk->sk_type)) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (sock->state != SS_UNCONNECTED) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	vsk = vsock_sk(sk);
+
+	if (!vsock_addr_bound(&vsk->local_addr)) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	sk->sk_max_ack_backlog = backlog;
+	sk->sk_state = TCP_LISTEN;
+
+	err = 0;
+
+out:
+	release_sock(sk);
+	return err;
+}
+
+static void vsock_update_buffer_size(struct vsock_sock *vsk,
+				     const struct vsock_transport *transport,
+				     u64 val)
+{
+	if (val < vsk->buffer_min_size)
+		val = vsk->buffer_min_size;
+
+	if (val > vsk->buffer_max_size)
+		val = vsk->buffer_max_size;
+
+	if (val != vsk->buffer_size &&
+	    transport && transport->notify_buffer_size)
+		transport->notify_buffer_size(vsk, &val);
+
+	vsk->buffer_size = val;
+}
+
+static int vsock_connectible_setsockopt(struct socket *sock,
+					int level,
+					int optname,
+					sockptr_t optval,
+					unsigned int optlen)
+{
+	int err;
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	const struct vsock_transport *transport;
+	u64 val;
+
+	if (level != AF_VSOCK && level != SOL_SOCKET)
+		return -ENOPROTOOPT;
+
+#define COPY_IN(_v)                                       \
+	do {						  \
+		if (optlen < sizeof(_v)) {		  \
+			err = -EINVAL;			  \
+			goto exit;			  \
+		}					  \
+		if (copy_from_sockptr(&_v, optval, sizeof(_v)) != 0) {	\
+			err = -EFAULT;					\
+			goto exit;					\
+		}							\
+	} while (0)
+
+	err = 0;
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+
+	lock_sock(sk);
+
+	transport = vsk->transport;
+
+	if (level == SOL_SOCKET) {
+		int zerocopy;
+
+		if (optname != SO_ZEROCOPY) {
+			release_sock(sk);
+			return sock_setsockopt(sock, level, optname, optval, optlen);
+		}
+
+		/* Use 'int' type here, because variable to
+		 * set this option usually has this type.
+		 */
+		COPY_IN(zerocopy);
+
+		if (zerocopy < 0 || zerocopy > 1) {
+			err = -EINVAL;
+			goto exit;
+		}
+
+		if (transport && !vsock_msgzerocopy_allow(transport)) {
+			err = -EOPNOTSUPP;
+			goto exit;
+		}
+
+		sock_valbool_flag(sk, SOCK_ZEROCOPY, zerocopy);
+		goto exit;
+	}
+
+	switch (optname) {
+	case SO_VM_SOCKETS_BUFFER_SIZE:
+		COPY_IN(val);
+		vsock_update_buffer_size(vsk, transport, val);
+		break;
+
+	case SO_VM_SOCKETS_BUFFER_MAX_SIZE:
+		COPY_IN(val);
+		vsk->buffer_max_size = val;
+		vsock_update_buffer_size(vsk, transport, vsk->buffer_size);
+		break;
+
+	case SO_VM_SOCKETS_BUFFER_MIN_SIZE:
+		COPY_IN(val);
+		vsk->buffer_min_size = val;
+		vsock_update_buffer_size(vsk, transport, vsk->buffer_size);
+		break;
+
+	case SO_VM_SOCKETS_CONNECT_TIMEOUT_NEW:
+	case SO_VM_SOCKETS_CONNECT_TIMEOUT_OLD: {
+		struct __kernel_sock_timeval tv;
+
+		err = sock_copy_user_timeval(&tv, optval, optlen,
+					     optname == SO_VM_SOCKETS_CONNECT_TIMEOUT_OLD);
+		if (err)
+			break;
+		if (tv.tv_sec >= 0 && tv.tv_usec < USEC_PER_SEC &&
+		    tv.tv_sec < (MAX_SCHEDULE_TIMEOUT / HZ - 1)) {
+			vsk->connect_timeout = tv.tv_sec * HZ +
+				DIV_ROUND_UP((unsigned long)tv.tv_usec, (USEC_PER_SEC / HZ));
+			if (vsk->connect_timeout == 0)
+				vsk->connect_timeout =
+				    VSOCK_DEFAULT_CONNECT_TIMEOUT;
+
+		} else {
+			err = -ERANGE;
+		}
+		break;
+	}
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+#undef COPY_IN
+
+exit:
+	release_sock(sk);
+	return err;
+}
+
+static int vsock_connectible_getsockopt(struct socket *sock,
+					int level, int optname,
+					sockopt_t *opt)
+{
+	struct sock *sk = sock->sk;
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	union {
+		u64 val64;
+		struct old_timeval32 tm32;
+		struct __kernel_old_timeval tm;
+		struct  __kernel_sock_timeval stm;
+	} v;
+
+	int lv = sizeof(v.val64);
+	int len;
+
+	if (level != AF_VSOCK)
+		return -ENOPROTOOPT;
+
+	len = opt->optlen;
+
+	memset(&v, 0, sizeof(v));
+
+	switch (optname) {
+	case SO_VM_SOCKETS_BUFFER_SIZE:
+		v.val64 = vsk->buffer_size;
+		break;
+
+	case SO_VM_SOCKETS_BUFFER_MAX_SIZE:
+		v.val64 = vsk->buffer_max_size;
+		break;
+
+	case SO_VM_SOCKETS_BUFFER_MIN_SIZE:
+		v.val64 = vsk->buffer_min_size;
+		break;
+
+	case SO_VM_SOCKETS_CONNECT_TIMEOUT_NEW:
+	case SO_VM_SOCKETS_CONNECT_TIMEOUT_OLD:
+		lv = sock_get_timeout(vsk->connect_timeout, &v,
+				      optname == SO_VM_SOCKETS_CONNECT_TIMEOUT_OLD);
+		break;
+
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	if (len < lv)
+		return -EINVAL;
+	if (len > lv)
+		len = lv;
+	if (copy_to_iter(&v, len, &opt->iter_out) != len)
+		return -EFAULT;
+
+	opt->optlen = len;
+
+	return 0;
+}
+
+static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
+				     size_t len)
+{
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	const struct vsock_transport *transport;
+	ssize_t total_written;
+	long timeout;
+	int err;
+	struct vsock_transport_send_notify_data send_data;
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+	sk = sock->sk;
+	vsk = vsock_sk(sk);
+	total_written = 0;
+	err = 0;
+
+	if (msg->msg_flags & MSG_OOB)
+		return -EOPNOTSUPP;
+
+	lock_sock(sk);
+
+	transport = vsk->transport;
+
+	/* Callers should not provide a destination with connection oriented
+	 * sockets.
+	 */
+	if (msg->msg_namelen) {
+		err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
+		goto out;
+	}
+
+	/* Send data only if both sides are not shutdown in the direction. */
+	if (sk->sk_shutdown & SEND_SHUTDOWN ||
+	    vsk->peer_shutdown & RCV_SHUTDOWN) {
+		err = -EPIPE;
+		goto out;
+	}
+
+	if (!transport || sk->sk_state != TCP_ESTABLISHED ||
+	    !vsock_addr_bound(&vsk->local_addr)) {
+		err = -ENOTCONN;
+		goto out;
+	}
+
+	if (!vsock_addr_bound(&vsk->remote_addr)) {
+		err = -EDESTADDRREQ;
+		goto out;
+	}
+
+	if (msg->msg_flags & MSG_ZEROCOPY &&
+	    !vsock_msgzerocopy_allow(transport)) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	/* Wait for room in the produce queue to enqueue our user's data. */
+	timeout = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
+
+	err = transport->notify_send_init(vsk, &send_data);
+	if (err < 0)
+		goto out;
+
+	while (total_written < len) {
+		ssize_t written;
+
+		add_wait_queue(sk_sleep(sk), &wait);
+		while (vsock_stream_has_space(vsk) == 0 &&
+		       sk->sk_err == 0 &&
+		       !(sk->sk_shutdown & SEND_SHUTDOWN) &&
+		       !(vsk->peer_shutdown & RCV_SHUTDOWN)) {
+
+			/* Don't wait for non-blocking sockets. */
+			if (timeout == 0) {
+				err = -EAGAIN;
+				remove_wait_queue(sk_sleep(sk), &wait);
+				goto out_err;
+			}
+
+			err = transport->notify_send_pre_block(vsk, &send_data);
+			if (err < 0) {
+				remove_wait_queue(sk_sleep(sk), &wait);
+				goto out_err;
+			}
+
+			release_sock(sk);
+			timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout);
+			lock_sock(sk);
+			if (signal_pending(current)) {
+				err = sock_intr_errno(timeout);
+				remove_wait_queue(sk_sleep(sk), &wait);
+				goto out_err;
+			} else if (timeout == 0) {
+				err = -EAGAIN;
+				remove_wait_queue(sk_sleep(sk), &wait);
+				goto out_err;
+			}
+		}
+		remove_wait_queue(sk_sleep(sk), &wait);
+
+		/* These checks occur both as part of and after the loop
+		 * conditional since we need to check before and after
+		 * sleeping.
+		 */
+		if (sk->sk_err) {
+			err = -sk->sk_err;
+			goto out_err;
+		} else if ((sk->sk_shutdown & SEND_SHUTDOWN) ||
+			   (vsk->peer_shutdown & RCV_SHUTDOWN)) {
+			err = -EPIPE;
+			goto out_err;
+		}
+
+		err = transport->notify_send_pre_enqueue(vsk, &send_data);
+		if (err < 0)
+			goto out_err;
+
+		/* Note that enqueue will only write as many bytes as are free
+		 * in the produce queue, so we don't need to ensure len is
+		 * smaller than the queue size.  It is the caller's
+		 * responsibility to check how many bytes we were able to send.
+		 */
+
+		if (sk->sk_type == SOCK_SEQPACKET) {
+			written = transport->seqpacket_enqueue(vsk,
+						msg, len - total_written);
+		} else {
+			written = transport->stream_enqueue(vsk,
+					msg, len - total_written);
+		}
+
+		if (written < 0) {
+			err = written;
+			goto out_err;
+		}
+
+		total_written += written;
+
+		err = transport->notify_send_post_enqueue(
+				vsk, written, &send_data);
+		if (err < 0)
+			goto out_err;
+
+	}
+
+out_err:
+	if (total_written > 0) {
+		/* Return number of written bytes only if:
+		 * 1) SOCK_STREAM socket.
+		 * 2) SOCK_SEQPACKET socket when whole buffer is sent.
+		 */
+		if (sk->sk_type == SOCK_STREAM || total_written == len)
+			err = total_written;
+	}
+out:
+	if (sk->sk_type == SOCK_STREAM)
+		err = sk_stream_error(sk, msg->msg_flags, err);
+
+	release_sock(sk);
+	return err;
+}
+
+static int vsock_connectible_wait_data(struct sock *sk,
+				       struct wait_queue_entry *wait,
+				       long timeout,
+				       struct vsock_transport_recv_notify_data *recv_data,
+				       size_t target)
+{
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+	s64 data;
+	int err;
+
+	vsk = vsock_sk(sk);
+	err = 0;
+	transport = vsk->transport;
+
+	while (1) {
+		prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
+		data = vsock_connectible_has_data(vsk);
+		if (data != 0)
+			break;
+
+		if (sk->sk_err != 0 ||
+		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
+		    (vsk->peer_shutdown & SEND_SHUTDOWN)) {
+			break;
+		}
+
+		/* Don't wait for non-blocking sockets. */
+		if (timeout == 0) {
+			err = -EAGAIN;
+			break;
+		}
+
+		if (recv_data) {
+			err = transport->notify_recv_pre_block(vsk, target, recv_data);
+			if (err < 0)
+				break;
+		}
+
+		release_sock(sk);
+		timeout = schedule_timeout(timeout);
+		lock_sock(sk);
+
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeout);
+			break;
+		} else if (timeout == 0) {
+			err = -EAGAIN;
+			break;
+		}
+	}
+
+	finish_wait(sk_sleep(sk), wait);
+
+	if (err)
+		return err;
+
+	/* Internal transport error when checking for available
+	 * data. XXX This should be changed to a connection
+	 * reset in a later change.
+	 */
+	if (data < 0)
+		return -ENOMEM;
+
+	return data;
+}
+
+static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
+				  size_t len, int flags)
+{
+	struct vsock_transport_recv_notify_data recv_data;
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+	ssize_t copied;
+	size_t target;
+	long timeout;
+	int err;
+
+	DEFINE_WAIT(wait);
+
+	vsk = vsock_sk(sk);
+	transport = vsk->transport;
+
+	/* We must not copy less than target bytes into the user's buffer
+	 * before returning successfully, so we wait for the consume queue to
+	 * have that much data to consume before dequeueing.  Note that this
+	 * makes it impossible to handle cases where target is greater than the
+	 * queue size.
+	 */
+	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
+	if (target >= transport->stream_rcvhiwat(vsk)) {
+		err = -ENOMEM;
+		goto out;
+	}
+	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+	copied = 0;
+
+	err = transport->notify_recv_init(vsk, target, &recv_data);
+	if (err < 0)
+		goto out;
+
+
+	while (1) {
+		ssize_t read;
+
+		err = vsock_connectible_wait_data(sk, &wait, timeout,
+						  &recv_data, target);
+		if (err <= 0)
+			break;
+
+		err = transport->notify_recv_pre_dequeue(vsk, target,
+							 &recv_data);
+		if (err < 0)
+			break;
+
+		read = transport->stream_dequeue(vsk, msg, len - copied, flags);
+		if (read < 0) {
+			err = read;
+			break;
+		}
+
+		copied += read;
+
+		err = transport->notify_recv_post_dequeue(vsk, target, read,
+						!(flags & MSG_PEEK), &recv_data);
+		if (err < 0)
+			goto out;
+
+		if (read >= target || flags & MSG_PEEK)
+			break;
+
+		target -= read;
+	}
+
+	if (sk->sk_err)
+		err = -sk->sk_err;
+	else if (sk->sk_shutdown & RCV_SHUTDOWN)
+		err = 0;
+
+	if (copied > 0)
+		err = copied;
+
+out:
+	return err;
+}
+
+static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
+				     size_t len, int flags)
+{
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+	ssize_t msg_len;
+	long timeout;
+	int err = 0;
+	DEFINE_WAIT(wait);
+
+	vsk = vsock_sk(sk);
+	transport = vsk->transport;
+
+	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+
+	err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
+	if (err <= 0)
+		goto out;
+
+	msg_len = transport->seqpacket_dequeue(vsk, msg, flags);
+
+	if (msg_len < 0) {
+		err = msg_len;
+		goto out;
+	}
+
+	if (sk->sk_err) {
+		err = -sk->sk_err;
+	} else if (sk->sk_shutdown & RCV_SHUTDOWN) {
+		err = 0;
+	} else {
+		/* User sets MSG_TRUNC, so return real length of
+		 * packet.
+		 */
+		if (flags & MSG_TRUNC)
+			err = msg_len;
+		else
+			err = len - msg_data_left(msg);
+
+		/* Always set MSG_TRUNC if real length of packet is
+		 * bigger than user's buffer.
+		 */
+		if (msg_len > len)
+			msg->msg_flags |= MSG_TRUNC;
+	}
+
+out:
+	return err;
+}
+
+int
+__vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+			    int flags)
+{
+	struct sock *sk;
+	struct vsock_sock *vsk;
+	const struct vsock_transport *transport;
+	int err;
+
+	sk = sock->sk;
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return sock_recv_errqueue(sk, msg, len, SOL_VSOCK, VSOCK_RECVERR);
+
+	vsk = vsock_sk(sk);
+	err = 0;
+
+	lock_sock(sk);
+
+	transport = vsk->transport;
+
+	if (!transport || sk->sk_state != TCP_ESTABLISHED) {
+		/* Recvmsg is supposed to return 0 if a peer performs an
+		 * orderly shutdown. Differentiate between that case and when a
+		 * peer has not connected or a local shutdown occurred with the
+		 * SOCK_DONE flag.
+		 */
+		if (sock_flag(sk, SOCK_DONE))
+			err = 0;
+		else
+			err = -ENOTCONN;
+
+		goto out;
+	}
+
+	if (flags & MSG_OOB) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	/* We don't check peer_shutdown flag here since peer may actually shut
+	 * down, but there can be data in the queue that a local socket can
+	 * receive.
+	 */
+	if (sk->sk_shutdown & RCV_SHUTDOWN) {
+		err = 0;
+		goto out;
+	}
+
+	/* It is valid on Linux to pass in a zero-length receive buffer.  This
+	 * is not an error.  We may as well bail out now.
+	 */
+	if (!len) {
+		err = 0;
+		goto out;
+	}
+
+	if (sk->sk_type == SOCK_STREAM)
+		err = __vsock_stream_recvmsg(sk, msg, len, flags);
+	else
+		err = __vsock_seqpacket_recvmsg(sk, msg, len, flags);
+
+out:
+	release_sock(sk);
+	return err;
+}
+
+int
+vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+			  int flags)
+{
+#ifdef CONFIG_BPF_SYSCALL
+	struct sock *sk = sock->sk;
+	const struct proto *prot;
+
+	prot = READ_ONCE(sk->sk_prot);
+	if (prot != &vsock_proto)
+		return prot->recvmsg(sk, msg, len, flags);
+#endif
+
+	return __vsock_connectible_recvmsg(sock, msg, len, flags);
+}
+EXPORT_SYMBOL_GPL(vsock_connectible_recvmsg);
+
+static int vsock_set_rcvlowat(struct sock *sk, int val)
+{
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+
+	if (val > vsk->buffer_size)
+		return -EINVAL;
+
+	transport = vsk->transport;
+
+	if (transport && transport->notify_set_rcvlowat) {
+		int err;
+
+		err = transport->notify_set_rcvlowat(vsk, val);
+		if (err)
+			return err;
+	}
+
+	WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
+	return 0;
+}
+
+static const struct proto_ops vsock_stream_ops = {
+	.family = PF_VSOCK,
+	.owner = THIS_MODULE,
+	.release = vsock_release,
+	.bind = vsock_bind,
+	.connect = vsock_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = vsock_accept,
+	.getname = vsock_getname,
+	.poll = vsock_poll,
+	.ioctl = vsock_ioctl,
+	.listen = vsock_listen,
+	.shutdown = vsock_shutdown,
+	.setsockopt = vsock_connectible_setsockopt,
+	.getsockopt_iter = vsock_connectible_getsockopt,
+	.sendmsg = vsock_connectible_sendmsg,
+	.recvmsg = vsock_connectible_recvmsg,
+	.mmap = sock_no_mmap,
+	.set_rcvlowat = vsock_set_rcvlowat,
+	.read_skb = vsock_read_skb,
+};
+
+static const struct proto_ops vsock_seqpacket_ops = {
+	.family = PF_VSOCK,
+	.owner = THIS_MODULE,
+	.release = vsock_release,
+	.bind = vsock_bind,
+	.connect = vsock_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = vsock_accept,
+	.getname = vsock_getname,
+	.poll = vsock_poll,
+	.ioctl = vsock_ioctl,
+	.listen = vsock_listen,
+	.shutdown = vsock_shutdown,
+	.setsockopt = vsock_connectible_setsockopt,
+	.getsockopt_iter = vsock_connectible_getsockopt,
+	.sendmsg = vsock_connectible_sendmsg,
+	.recvmsg = vsock_connectible_recvmsg,
+	.mmap = sock_no_mmap,
+	.read_skb = vsock_read_skb,
+};
+
+static int vsock_create(struct net *net, struct socket *sock,
+			int protocol, int kern)
+{
+	struct vsock_sock *vsk;
+	struct sock *sk;
+	int ret;
+
+	if (!sock)
+		return -EINVAL;
+
+	if (protocol && protocol != PF_VSOCK)
+		return -EPROTONOSUPPORT;
+
+	switch (sock->type) {
+	case SOCK_DGRAM:
+		sock->ops = &vsock_dgram_ops;
+		break;
+	case SOCK_STREAM:
+		sock->ops = &vsock_stream_ops;
+		break;
+	case SOCK_SEQPACKET:
+		sock->ops = &vsock_seqpacket_ops;
+		break;
+	default:
+		return -ESOCKTNOSUPPORT;
+	}
+
+	sock->state = SS_UNCONNECTED;
+
+	sk = __vsock_create(net, sock, NULL, GFP_KERNEL, 0, kern);
+	if (!sk)
+		return -ENOMEM;
+
+	vsk = vsock_sk(sk);
+
+	if (sock->type == SOCK_DGRAM) {
+		ret = vsock_assign_transport(vsk, NULL);
+		if (ret < 0) {
+			sock->sk = NULL;
+			sock_put(sk);
+			return ret;
+		}
+	}
+
+	/* SOCK_DGRAM doesn't have 'setsockopt' callback set in its
+	 * proto_ops, so there is no handler for custom logic.
+	 */
+	if (sock_type_connectible(sock->type))
+		set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
+
+	vsock_insert_unbound(vsk);
+
+	return 0;
+}
+
+static const struct net_proto_family vsock_family_ops = {
+	.family = AF_VSOCK,
+	.create = vsock_create,
+	.owner = THIS_MODULE,
+};
+
+static long vsock_dev_do_ioctl(struct file *filp,
+			       unsigned int cmd, void __user *ptr)
+{
+	u32 __user *p = ptr;
+	int retval = 0;
+	u32 cid;
+
+	switch (cmd) {
+	case IOCTL_VM_SOCKETS_GET_LOCAL_CID:
+		/* To be compatible with the VMCI behavior, we prioritize the
+		 * guest CID instead of well-know host CID (VMADDR_CID_HOST).
+		 */
+		cid = vsock_registered_transport_cid(&transport_g2h);
+		if (cid == VMADDR_CID_ANY)
+			cid = vsock_registered_transport_cid(&transport_h2g);
+		if (cid == VMADDR_CID_ANY)
+			cid = vsock_registered_transport_cid(&transport_local);
+
+		if (put_user(cid, p) != 0)
+			retval = -EFAULT;
+		break;
+
+	default:
+		retval = -ENOIOCTLCMD;
+	}
+
+	return retval;
+}
+
+static long vsock_dev_ioctl(struct file *filp,
+			    unsigned int cmd, unsigned long arg)
+{
+	return vsock_dev_do_ioctl(filp, cmd, (void __user *)arg);
+}
+
+#ifdef CONFIG_COMPAT
+static long vsock_dev_compat_ioctl(struct file *filp,
+				   unsigned int cmd, unsigned long arg)
+{
+	return vsock_dev_do_ioctl(filp, cmd, compat_ptr(arg));
+}
+#endif
+
+static const struct file_operations vsock_device_ops = {
+	.owner		= THIS_MODULE,
+	.unlocked_ioctl	= vsock_dev_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= vsock_dev_compat_ioctl,
+#endif
+	.open		= nonseekable_open,
+};
+
+static struct miscdevice vsock_device = {
+	.name		= "vsock",
+	.fops		= &vsock_device_ops,
+};
+
+static int __vsock_net_mode_string(const struct ctl_table *table, int write,
+				   void *buffer, size_t *lenp, loff_t *ppos,
+				   enum vsock_net_mode mode,
+				   enum vsock_net_mode *new_mode)
+{
+	char data[VSOCK_NET_MODE_STR_MAX] = {0};
+	struct ctl_table tmp;
+	int ret;
+
+	if (!table->data || !table->maxlen || !*lenp) {
+		*lenp = 0;
+		return 0;
+	}
+
+	tmp = *table;
+	tmp.data = data;
+
+	if (!write) {
+		const char *p;
+
+		switch (mode) {
+		case VSOCK_NET_MODE_GLOBAL:
+			p = VSOCK_NET_MODE_STR_GLOBAL;
+			break;
+		case VSOCK_NET_MODE_LOCAL:
+			p = VSOCK_NET_MODE_STR_LOCAL;
+			break;
+		default:
+			WARN_ONCE(true, "netns has invalid vsock mode");
+			*lenp = 0;
+			return 0;
+		}
+
+		strscpy(data, p, sizeof(data));
+		tmp.maxlen = strlen(p);
+	}
+
+	ret = proc_dostring(&tmp, write, buffer, lenp, ppos);
+	if (ret || !write)
+		return ret;
+
+	if (*lenp >= sizeof(data))
+		return -EINVAL;
+
+	if (!strncmp(data, VSOCK_NET_MODE_STR_GLOBAL, sizeof(data)))
+		*new_mode = VSOCK_NET_MODE_GLOBAL;
+	else if (!strncmp(data, VSOCK_NET_MODE_STR_LOCAL, sizeof(data)))
+		*new_mode = VSOCK_NET_MODE_LOCAL;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int vsock_net_mode_string(const struct ctl_table *table, int write,
+				 void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct net *net;
+
+	if (write)
+		return -EPERM;
+
+	net = container_of(table->data, struct net, vsock.mode);
+
+	return __vsock_net_mode_string(table, write, buffer, lenp, ppos,
+				       vsock_net_mode(net), NULL);
+}
+
+static int vsock_net_child_mode_string(const struct ctl_table *table, int write,
+				       void *buffer, size_t *lenp, loff_t *ppos)
+{
+	enum vsock_net_mode new_mode;
+	struct net *net;
+	int ret;
+
+	net = container_of(table->data, struct net, vsock.child_ns_mode);
+
+	ret = __vsock_net_mode_string(table, write, buffer, lenp, ppos,
+				      vsock_net_child_mode(net), &new_mode);
+	if (ret)
+		return ret;
+
+	if (write) {
+		/* Prevent a "local" namespace from escalating to "global",
+		 * which would give nested namespaces access to global CIDs.
+		 */
+		if (vsock_net_mode(net) == VSOCK_NET_MODE_LOCAL &&
+		    new_mode == VSOCK_NET_MODE_GLOBAL)
+			return -EPERM;
+
+		if (!vsock_net_set_child_mode(net, new_mode))
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+static const struct ctl_table vsock_table[] = {
+	{
+		.procname	= "ns_mode",
+		.data		= &init_net.vsock.mode,
+		.maxlen		= VSOCK_NET_MODE_STR_MAX,
+		.mode		= 0444,
+		.proc_handler	= vsock_net_mode_string
+	},
+	{
+		.procname	= "child_ns_mode",
+		.data		= &init_net.vsock.child_ns_mode,
+		.maxlen		= VSOCK_NET_MODE_STR_MAX,
+		.mode		= 0644,
+		.proc_handler	= vsock_net_child_mode_string
+	},
+	{
+		.procname	= "g2h_fallback",
+		.data		= &init_net.vsock.g2h_fallback,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+};
+
+static const struct ctl_table *vsock_table_dup(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = kmemdup(vsock_table, sizeof(vsock_table), GFP_KERNEL);
+	if (!table)
+		return NULL;
+
+	table[0].data = &net->vsock.mode;
+	table[1].data = &net->vsock.child_ns_mode;
+	table[2].data = &net->vsock.g2h_fallback;
+
+	return table;
+}
+
+static int __net_init vsock_sysctl_register(struct net *net)
+{
+	const struct ctl_table *table;
+
+	if (net_eq(net, &init_net)) {
+		table = vsock_table;
+	} else {
+		table = vsock_table_dup(net);
+		if (!table)
+			goto err_alloc;
+	}
+
+	net->vsock.sysctl_hdr = register_net_sysctl_sz(net, "net/vsock", table,
+						       ARRAY_SIZE(vsock_table));
+	if (!net->vsock.sysctl_hdr)
+		goto err_reg;
+
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static void vsock_sysctl_unregister(struct net *net)
+{
+	const struct ctl_table *table;
+
+	table = net->vsock.sysctl_hdr->ctl_table_arg;
+	unregister_net_sysctl_table(net->vsock.sysctl_hdr);
+	if (!net_eq(net, &init_net))
+		kfree(table);
+}
+
+static void vsock_net_init(struct net *net)
+{
+	if (net_eq(net, &init_net))
+		net->vsock.mode = VSOCK_NET_MODE_GLOBAL;
+	else
+		net->vsock.mode = vsock_net_child_mode(current->nsproxy->net_ns);
+
+	net->vsock.child_ns_mode = net->vsock.mode;
+	net->vsock.child_ns_mode_locked = 0;
+	net->vsock.g2h_fallback = 1;
+}
+
+static __net_init int vsock_sysctl_init_net(struct net *net)
+{
+	vsock_net_init(net);
+
+	if (vsock_sysctl_register(net))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static __net_exit void vsock_sysctl_exit_net(struct net *net)
+{
+	vsock_sysctl_unregister(net);
+}
+
+static struct pernet_operations vsock_sysctl_ops = {
+	.init = vsock_sysctl_init_net,
+	.exit = vsock_sysctl_exit_net,
+};
+
+static int __init vsock_init(void)
+{
+	int err = 0;
+
+	vsock_init_tables();
+
+	vsock_proto.owner = THIS_MODULE;
+	vsock_device.minor = MISC_DYNAMIC_MINOR;
+	err = misc_register(&vsock_device);
+	if (err) {
+		pr_err("Failed to register misc device\n");
+		goto err_reset_transport;
+	}
+
+	err = proto_register(&vsock_proto, 1);	/* we want our slab */
+	if (err) {
+		pr_err("Cannot register vsock protocol\n");
+		goto err_deregister_misc;
+	}
+
+	err = sock_register(&vsock_family_ops);
+	if (err) {
+		pr_err("could not register af_vsock (%d) address family: %d\n",
+		       AF_VSOCK, err);
+		goto err_unregister_proto;
+	}
+
+	if (register_pernet_subsys(&vsock_sysctl_ops)) {
+		err = -ENOMEM;
+		goto err_unregister_sock;
+	}
+
+	vsock_bpf_build_proto();
+
+	return 0;
+
+err_unregister_sock:
+	sock_unregister(AF_VSOCK);
+err_unregister_proto:
+	proto_unregister(&vsock_proto);
+err_deregister_misc:
+	misc_deregister(&vsock_device);
+err_reset_transport:
+	return err;
+}
+
+static void __exit vsock_exit(void)
+{
+	misc_deregister(&vsock_device);
+	sock_unregister(AF_VSOCK);
+	proto_unregister(&vsock_proto);
+	unregister_pernet_subsys(&vsock_sysctl_ops);
+}
+
+const struct vsock_transport *vsock_core_get_transport(struct vsock_sock *vsk)
+{
+	return vsk->transport;
+}
+EXPORT_SYMBOL_GPL(vsock_core_get_transport);
+
+int vsock_core_register(const struct vsock_transport *t, int features)
+{
+	const struct vsock_transport *t_h2g, *t_g2h, *t_dgram, *t_local;
+	int err = mutex_lock_interruptible(&vsock_register_mutex);
+
+	if (err)
+		return err;
+
+	t_h2g = transport_h2g;
+	t_g2h = transport_g2h;
+	t_dgram = transport_dgram;
+	t_local = transport_local;
+
+	if (features & VSOCK_TRANSPORT_F_H2G) {
+		if (t_h2g) {
+			err = -EBUSY;
+			goto err_busy;
+		}
+		t_h2g = t;
+	}
+
+	if (features & VSOCK_TRANSPORT_F_G2H) {
+		if (t_g2h) {
+			err = -EBUSY;
+			goto err_busy;
+		}
+		t_g2h = t;
+	}
+
+	if (features & VSOCK_TRANSPORT_F_DGRAM) {
+		if (t_dgram) {
+			err = -EBUSY;
+			goto err_busy;
+		}
+		t_dgram = t;
+	}
+
+	if (features & VSOCK_TRANSPORT_F_LOCAL) {
+		if (t_local) {
+			err = -EBUSY;
+			goto err_busy;
+		}
+		t_local = t;
+	}
+
+	transport_h2g = t_h2g;
+	transport_g2h = t_g2h;
+	transport_dgram = t_dgram;
+	transport_local = t_local;
+
+err_busy:
+	mutex_unlock(&vsock_register_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(vsock_core_register);
+
+void vsock_core_unregister(const struct vsock_transport *t)
+{
+	mutex_lock(&vsock_register_mutex);
+
+	if (transport_h2g == t)
+		transport_h2g = NULL;
+
+	if (transport_g2h == t)
+		transport_g2h = NULL;
+
+	if (transport_dgram == t)
+		transport_dgram = NULL;
+
+	if (transport_local == t)
+		transport_local = NULL;
+
+	mutex_unlock(&vsock_register_mutex);
+}
+EXPORT_SYMBOL_GPL(vsock_core_unregister);
+
+module_init(vsock_init);
+module_exit(vsock_exit);
+
+MODULE_AUTHOR("VMware, Inc.");
+MODULE_DESCRIPTION("VMware Virtual Socket Family");
+MODULE_VERSION("1.0.2.0-k");
+MODULE_LICENSE("GPL v2");
diff --git a/net/vmw_vsock/af_vsock_tap.c b/net/vmw_vsock/af_vsock_tap.c
new file mode 100644
index 000000000..30ee7e4fe
--- /dev/null
+++ b/net/vmw_vsock/af_vsock_tap.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Tap functions for AF_VSOCK sockets.
+ *
+ * Code based on net/netlink/af_netlink.c tap functions.
+ */
+
+#include <linux/module.h>
+#include <net/sock.h>
+#include <net/af_vsock.h>
+#include <linux/if_arp.h>
+
+static DEFINE_SPINLOCK(vsock_tap_lock);
+static struct list_head vsock_tap_all __read_mostly =
+				LIST_HEAD_INIT(vsock_tap_all);
+
+int vsock_add_tap(struct vsock_tap *vt)
+{
+	if (unlikely(vt->dev->type != ARPHRD_VSOCKMON))
+		return -EINVAL;
+
+	__module_get(vt->module);
+
+	spin_lock(&vsock_tap_lock);
+	list_add_rcu(&vt->list, &vsock_tap_all);
+	spin_unlock(&vsock_tap_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vsock_add_tap);
+
+int vsock_remove_tap(struct vsock_tap *vt)
+{
+	struct vsock_tap *tmp;
+	bool found = false;
+
+	spin_lock(&vsock_tap_lock);
+
+	list_for_each_entry(tmp, &vsock_tap_all, list) {
+		if (vt == tmp) {
+			list_del_rcu(&vt->list);
+			found = true;
+			goto out;
+		}
+	}
+
+	pr_warn("vsock_remove_tap: %p not found\n", vt);
+out:
+	spin_unlock(&vsock_tap_lock);
+
+	synchronize_net();
+
+	if (found)
+		module_put(vt->module);
+
+	return found ? 0 : -ENODEV;
+}
+EXPORT_SYMBOL_GPL(vsock_remove_tap);
+
+static int __vsock_deliver_tap_skb(struct sk_buff *skb,
+				   struct net_device *dev)
+{
+	int ret = 0;
+	struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
+	if (nskb) {
+		dev_hold(dev);
+
+		nskb->dev = dev;
+		ret = dev_queue_xmit(nskb);
+		if (unlikely(ret > 0))
+			ret = net_xmit_errno(ret);
+
+		dev_put(dev);
+	}
+
+	return ret;
+}
+
+static void __vsock_deliver_tap(struct sk_buff *skb)
+{
+	int ret;
+	struct vsock_tap *tmp;
+
+	list_for_each_entry_rcu(tmp, &vsock_tap_all, list) {
+		ret = __vsock_deliver_tap_skb(skb, tmp->dev);
+		if (unlikely(ret))
+			break;
+	}
+}
+
+void vsock_deliver_tap(struct sk_buff *build_skb(void *opaque), void *opaque)
+{
+	struct sk_buff *skb;
+
+	rcu_read_lock();
+
+	if (likely(list_empty(&vsock_tap_all)))
+		goto out;
+
+	skb = build_skb(opaque);
+	if (skb) {
+		__vsock_deliver_tap(skb);
+		consume_skb(skb);
+	}
+
+out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(vsock_deliver_tap);
diff --git a/net/vmw_vsock/diag.c b/net/vmw_vsock/diag.c
new file mode 100644
index 000000000..ab87ef66c
--- /dev/null
+++ b/net/vmw_vsock/diag.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vsock sock_diag(7) module
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ * Author: Stefan Hajnoczi <stefanha@redhat.com>
+ */
+
+#include <linux/module.h>
+#include <linux/sock_diag.h>
+#include <linux/vm_sockets_diag.h>
+#include <net/af_vsock.h>
+
+static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
+			u32 portid, u32 seq, u32 flags)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+	struct vsock_diag_msg *rep;
+	struct nlmsghdr *nlh;
+
+	nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
+			flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	rep = nlmsg_data(nlh);
+	rep->vdiag_family = AF_VSOCK;
+
+	/* Lock order dictates that sk_lock is acquired before
+	 * vsock_table_lock, so we cannot lock here.  Simply don't take
+	 * sk_lock; sk is guaranteed to stay alive since vsock_table_lock is
+	 * held.
+	 */
+	rep->vdiag_type = sk->sk_type;
+	rep->vdiag_state = sk->sk_state;
+	rep->vdiag_shutdown = sk->sk_shutdown;
+	rep->vdiag_src_cid = vsk->local_addr.svm_cid;
+	rep->vdiag_src_port = vsk->local_addr.svm_port;
+	rep->vdiag_dst_cid = vsk->remote_addr.svm_cid;
+	rep->vdiag_dst_port = vsk->remote_addr.svm_port;
+	rep->vdiag_ino = sock_i_ino(sk);
+
+	sock_diag_save_cookie(sk, rep->vdiag_cookie);
+
+	return 0;
+}
+
+static int vsock_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct vsock_diag_req *req;
+	struct vsock_sock *vsk;
+	unsigned int bucket;
+	unsigned int last_i;
+	unsigned int table;
+	struct net *net;
+	unsigned int i;
+
+	req = nlmsg_data(cb->nlh);
+	net = sock_net(skb->sk);
+
+	/* State saved between calls: */
+	table = cb->args[0];
+	bucket = cb->args[1];
+	i = last_i = cb->args[2];
+
+	/* TODO VMCI pending sockets? */
+
+	spin_lock_bh(&vsock_table_lock);
+
+	/* Bind table (locally created sockets) */
+	if (table == 0) {
+		while (bucket < ARRAY_SIZE(vsock_bind_table)) {
+			struct list_head *head = &vsock_bind_table[bucket];
+
+			i = 0;
+			list_for_each_entry(vsk, head, bound_table) {
+				struct sock *sk = sk_vsock(vsk);
+
+				if (!net_eq(sock_net(sk), net))
+					continue;
+				if (i < last_i)
+					goto next_bind;
+				if (!(req->vdiag_states & (1 << sk->sk_state)))
+					goto next_bind;
+				if (sk_diag_fill(sk, skb,
+						 NETLINK_CB(cb->skb).portid,
+						 cb->nlh->nlmsg_seq,
+						 NLM_F_MULTI) < 0)
+					goto done;
+next_bind:
+				i++;
+			}
+			last_i = 0;
+			bucket++;
+		}
+
+		table++;
+		bucket = 0;
+	}
+
+	/* Connected table (accepted connections) */
+	while (bucket < ARRAY_SIZE(vsock_connected_table)) {
+		struct list_head *head = &vsock_connected_table[bucket];
+
+		i = 0;
+		list_for_each_entry(vsk, head, connected_table) {
+			struct sock *sk = sk_vsock(vsk);
+
+			/* Skip sockets we've already seen above */
+			if (__vsock_in_bound_table(vsk))
+				continue;
+
+			if (!net_eq(sock_net(sk), net))
+				continue;
+			if (i < last_i)
+				goto next_connected;
+			if (!(req->vdiag_states & (1 << sk->sk_state)))
+				goto next_connected;
+			if (sk_diag_fill(sk, skb,
+					 NETLINK_CB(cb->skb).portid,
+					 cb->nlh->nlmsg_seq,
+					 NLM_F_MULTI) < 0)
+				goto done;
+next_connected:
+			i++;
+		}
+		last_i = 0;
+		bucket++;
+	}
+
+done:
+	spin_unlock_bh(&vsock_table_lock);
+
+	cb->args[0] = table;
+	cb->args[1] = bucket;
+	cb->args[2] = i;
+
+	return skb->len;
+}
+
+static int vsock_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
+{
+	int hdrlen = sizeof(struct vsock_diag_req);
+	struct net *net = sock_net(skb->sk);
+
+	if (nlmsg_len(h) < hdrlen)
+		return -EINVAL;
+
+	if (h->nlmsg_flags & NLM_F_DUMP) {
+		struct netlink_dump_control c = {
+			.dump = vsock_diag_dump,
+		};
+		return netlink_dump_start(net->diag_nlsk, skb, h, &c);
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const struct sock_diag_handler vsock_diag_handler = {
+	.owner = THIS_MODULE,
+	.family = AF_VSOCK,
+	.dump = vsock_diag_handler_dump,
+};
+
+static int __init vsock_diag_init(void)
+{
+	return sock_diag_register(&vsock_diag_handler);
+}
+
+static void __exit vsock_diag_exit(void)
+{
+	sock_diag_unregister(&vsock_diag_handler);
+}
+
+module_init(vsock_diag_init);
+module_exit(vsock_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("VMware Virtual Sockets monitoring via SOCK_DIAG");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG,
+			       40 /* AF_VSOCK */);
diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
new file mode 100644
index 000000000..5405c2680
--- /dev/null
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -0,0 +1,992 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Hyper-V transport for vsock
+ *
+ * Hyper-V Sockets supplies a byte-stream based communication mechanism
+ * between the host and the VM. This driver implements the necessary
+ * support in the VM by introducing the new vsock transport.
+ *
+ * Copyright (c) 2017, Microsoft Corporation.
+ */
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/hyperv.h>
+#include <net/sock.h>
+#include <net/af_vsock.h>
+#include <hyperv/hvhdk.h>
+
+/* Older (VMBUS version 'VERSION_WIN10' or before) Windows hosts have some
+ * stricter requirements on the hv_sock ring buffer size of six 4K pages.
+ * HV_HYP_PAGE_SIZE is defined as 4K. Newer hosts don't have this limitation;
+ * but, keep the defaults the same for compat.
+ */
+#define RINGBUFFER_HVS_RCV_SIZE (HV_HYP_PAGE_SIZE * 6)
+#define RINGBUFFER_HVS_SND_SIZE (HV_HYP_PAGE_SIZE * 6)
+#define RINGBUFFER_HVS_MAX_SIZE (HV_HYP_PAGE_SIZE * 64)
+
+/* The MTU is 16KB per the host side's design */
+#define HVS_MTU_SIZE		(1024 * 16)
+
+/* How long to wait for graceful shutdown of a connection */
+#define HVS_CLOSE_TIMEOUT (8 * HZ)
+
+struct vmpipe_proto_header {
+	u32 pkt_type;
+	u32 data_size;
+};
+
+/* For recv, we use the VMBus in-place packet iterator APIs to directly copy
+ * data from the ringbuffer into the userspace buffer.
+ */
+struct hvs_recv_buf {
+	/* The header before the payload data */
+	struct vmpipe_proto_header hdr;
+
+	/* The payload */
+	u8 data[HVS_MTU_SIZE];
+};
+
+/* We can send up to HVS_MTU_SIZE bytes of payload to the host, but let's use
+ * a smaller size, i.e. HVS_SEND_BUF_SIZE, to maximize concurrency between the
+ * guest and the host processing as one VMBUS packet is the smallest processing
+ * unit.
+ *
+ * Note: the buffer can be eliminated in the future when we add new VMBus
+ * ringbuffer APIs that allow us to directly copy data from userspace buffer
+ * to VMBus ringbuffer.
+ */
+#define HVS_SEND_BUF_SIZE \
+		(HV_HYP_PAGE_SIZE - sizeof(struct vmpipe_proto_header))
+
+struct hvs_send_buf {
+	/* The header before the payload data */
+	struct vmpipe_proto_header hdr;
+
+	/* The payload */
+	u8 data[HVS_SEND_BUF_SIZE];
+};
+
+#define HVS_HEADER_LEN	(sizeof(struct vmpacket_descriptor) + \
+			 sizeof(struct vmpipe_proto_header))
+
+/* See 'prev_indices' in hv_ringbuffer_read(), hv_ringbuffer_write(), and
+ * __hv_pkt_iter_next().
+ */
+#define VMBUS_PKT_TRAILER_SIZE	(sizeof(u64))
+
+#define HVS_PKT_LEN(payload_len)	(HVS_HEADER_LEN + \
+					 ALIGN((payload_len), 8) + \
+					 VMBUS_PKT_TRAILER_SIZE)
+
+/* Upper bound on the size of a VMbus packet for hv_sock */
+#define HVS_MAX_PKT_SIZE	HVS_PKT_LEN(HVS_MTU_SIZE)
+
+union hvs_service_id {
+	guid_t	srv_id;
+
+	struct {
+		unsigned int svm_port;
+		unsigned char b[sizeof(guid_t) - sizeof(unsigned int)];
+	};
+};
+
+/* Per-socket state (accessed via vsk->trans) */
+struct hvsock {
+	struct vsock_sock *vsk;
+
+	guid_t vm_srv_id;
+	guid_t host_srv_id;
+
+	struct vmbus_channel *chan;
+	struct vmpacket_descriptor *recv_desc;
+
+	/* The length of the payload not delivered to userland yet */
+	u32 recv_data_len;
+	/* The offset of the payload */
+	u32 recv_data_off;
+
+	/* Have we sent the zero-length packet (FIN)? */
+	bool fin_sent;
+};
+
+/* In the VM, we support Hyper-V Sockets with AF_VSOCK, and the endpoint is
+ * <cid, port> (see struct sockaddr_vm). Note: cid is not really used here:
+ * when we write apps to connect to the host, we can only use VMADDR_CID_ANY
+ * or VMADDR_CID_HOST (both are equivalent) as the remote cid, and when we
+ * write apps to bind() & listen() in the VM, we can only use VMADDR_CID_ANY
+ * as the local cid.
+ *
+ * On the host, Hyper-V Sockets are supported by Winsock AF_HYPERV:
+ * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/user-
+ * guide/make-integration-service, and the endpoint is <VmID, ServiceId> with
+ * the below sockaddr:
+ *
+ * struct SOCKADDR_HV
+ * {
+ *    ADDRESS_FAMILY Family;
+ *    USHORT Reserved;
+ *    GUID VmId;
+ *    GUID ServiceId;
+ * };
+ * Note: VmID is not used by Linux VM and actually it isn't transmitted via
+ * VMBus, because here it's obvious the host and the VM can easily identify
+ * each other. Though the VmID is useful on the host, especially in the case
+ * of Windows container, Linux VM doesn't need it at all.
+ *
+ * To make use of the AF_VSOCK infrastructure in Linux VM, we have to limit
+ * the available GUID space of SOCKADDR_HV so that we can create a mapping
+ * between AF_VSOCK port and SOCKADDR_HV Service GUID. The rule of writing
+ * Hyper-V Sockets apps on the host and in Linux VM is:
+ *
+ ****************************************************************************
+ * The only valid Service GUIDs, from the perspectives of both the host and *
+ * Linux VM, that can be connected by the other end, must conform to this   *
+ * format: <port>-facb-11e6-bd58-64006a7986d3.                              *
+ ****************************************************************************
+ *
+ * When we write apps on the host to connect(), the GUID ServiceID is used.
+ * When we write apps in Linux VM to connect(), we only need to specify the
+ * port and the driver will form the GUID and use that to request the host.
+ *
+ */
+
+/* 00000000-facb-11e6-bd58-64006a7986d3 */
+static const guid_t srv_id_template =
+	GUID_INIT(0x00000000, 0xfacb, 0x11e6, 0xbd, 0x58,
+		  0x64, 0x00, 0x6a, 0x79, 0x86, 0xd3);
+
+static bool hvs_check_transport(struct vsock_sock *vsk);
+
+static bool is_valid_srv_id(const guid_t *id)
+{
+	return !memcmp(&id->b[4], &srv_id_template.b[4], sizeof(guid_t) - 4);
+}
+
+static unsigned int get_port_by_srv_id(const guid_t *svr_id)
+{
+	return *((unsigned int *)svr_id);
+}
+
+static void hvs_addr_init(struct sockaddr_vm *addr, const guid_t *svr_id)
+{
+	unsigned int port = get_port_by_srv_id(svr_id);
+
+	vsock_addr_init(addr, VMADDR_CID_ANY, port);
+}
+
+static void hvs_set_channel_pending_send_size(struct vmbus_channel *chan)
+{
+	set_channel_pending_send_size(chan,
+				      HVS_PKT_LEN(HVS_SEND_BUF_SIZE));
+
+	virt_mb();
+}
+
+static bool hvs_channel_readable(struct vmbus_channel *chan)
+{
+	u32 readable = hv_get_bytes_to_read(&chan->inbound);
+
+	/* 0-size payload means FIN */
+	return readable >= HVS_PKT_LEN(0);
+}
+
+static int hvs_channel_readable_payload(struct vmbus_channel *chan)
+{
+	u32 readable = hv_get_bytes_to_read(&chan->inbound);
+
+	if (readable > HVS_PKT_LEN(0)) {
+		/* At least we have 1 byte to read. We don't need to return
+		 * the exact readable bytes: see vsock_connectible_recvmsg() ->
+		 * vsock_stream_has_data().
+		 */
+		return 1;
+	}
+
+	if (readable == HVS_PKT_LEN(0)) {
+		/* 0-size payload means FIN */
+		return 0;
+	}
+
+	/* No payload or FIN */
+	return -1;
+}
+
+static size_t hvs_channel_writable_bytes(struct vmbus_channel *chan)
+{
+	u32 writeable = hv_get_bytes_to_write(&chan->outbound);
+	size_t ret;
+
+	/* The ringbuffer mustn't be 100% full, and we should reserve a
+	 * zero-length-payload packet for the FIN: see hv_ringbuffer_write()
+	 * and hvs_shutdown().
+	 */
+	if (writeable <= HVS_PKT_LEN(1) + HVS_PKT_LEN(0))
+		return 0;
+
+	ret = writeable - HVS_PKT_LEN(1) - HVS_PKT_LEN(0);
+
+	return round_down(ret, 8);
+}
+
+static int __hvs_send_data(struct vmbus_channel *chan,
+			   struct vmpipe_proto_header *hdr,
+			   size_t to_write)
+{
+	hdr->pkt_type = 1;
+	hdr->data_size = to_write;
+	return vmbus_sendpacket(chan, hdr, sizeof(*hdr) + to_write,
+				0, VM_PKT_DATA_INBAND, 0);
+}
+
+static int hvs_send_data(struct vmbus_channel *chan,
+			 struct hvs_send_buf *send_buf, size_t to_write)
+{
+	return __hvs_send_data(chan, &send_buf->hdr, to_write);
+}
+
+static void hvs_channel_cb(void *ctx)
+{
+	struct sock *sk = (struct sock *)ctx;
+	struct vsock_sock *vsk = vsock_sk(sk);
+	struct hvsock *hvs = vsk->trans;
+	struct vmbus_channel *chan = hvs->chan;
+
+	if (hvs_channel_readable(chan))
+		sk->sk_data_ready(sk);
+
+	if (hv_get_bytes_to_write(&chan->outbound) > 0)
+		sk->sk_write_space(sk);
+}
+
+static void hvs_do_close_lock_held(struct vsock_sock *vsk,
+				   bool cancel_timeout)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_set_flag(sk, SOCK_DONE);
+	WRITE_ONCE(vsk->peer_shutdown, SHUTDOWN_MASK);
+	if (vsock_stream_has_data(vsk) <= 0)
+		sk->sk_state = TCP_CLOSING;
+	sk->sk_state_change(sk);
+	if (vsk->close_work_scheduled &&
+	    (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) {
+		vsk->close_work_scheduled = false;
+		vsock_remove_sock(vsk);
+
+		/* Release the reference taken while scheduling the timeout */
+		sock_put(sk);
+	}
+}
+
+static void hvs_close_connection(struct vmbus_channel *chan)
+{
+	struct sock *sk = get_per_channel_state(chan);
+
+	lock_sock(sk);
+	hvs_do_close_lock_held(vsock_sk(sk), true);
+	release_sock(sk);
+
+	/* Release the refcnt for the channel that's opened in
+	 * hvs_open_connection().
+	 */
+	sock_put(sk);
+}
+
+static void hvs_open_connection(struct vmbus_channel *chan)
+{
+	guid_t *if_instance, *if_type;
+	unsigned char conn_from_host;
+
+	struct sockaddr_vm addr;
+	struct sock *sk, *new = NULL;
+	struct vsock_sock *vnew = NULL;
+	struct hvsock *hvs = NULL;
+	struct hvsock *hvs_new = NULL;
+	int rcvbuf;
+	int ret;
+	int sndbuf;
+
+	if_type = &chan->offermsg.offer.if_type;
+	if_instance = &chan->offermsg.offer.if_instance;
+	conn_from_host = chan->offermsg.offer.u.pipe.user_def[0];
+	if (!is_valid_srv_id(if_type))
+		return;
+
+	hvs_addr_init(&addr, conn_from_host ? if_type : if_instance);
+	sk = vsock_find_bound_socket(&addr);
+	if (!sk)
+		return;
+
+	lock_sock(sk);
+	if ((conn_from_host && sk->sk_state != TCP_LISTEN) ||
+	    (!conn_from_host && sk->sk_state != TCP_SYN_SENT))
+		goto out;
+
+	if (conn_from_host) {
+		if (sk_acceptq_is_full(sk))
+			goto out;
+
+		new = vsock_create_connected(sk);
+		if (!new)
+			goto out;
+
+		new->sk_state = TCP_SYN_SENT;
+		vnew = vsock_sk(new);
+
+		hvs_addr_init(&vnew->local_addr, if_type);
+
+		/* Remote peer is always the host */
+		vsock_addr_init(&vnew->remote_addr,
+				VMADDR_CID_HOST, VMADDR_PORT_ANY);
+		vnew->remote_addr.svm_port = get_port_by_srv_id(if_instance);
+		ret = vsock_assign_transport(vnew, vsock_sk(sk));
+		/* Transport assigned (looking at remote_addr) must be the
+		 * same where we received the request.
+		 */
+		if (ret || !hvs_check_transport(vnew)) {
+			sock_put(new);
+			goto out;
+		}
+		hvs_new = vnew->trans;
+		hvs_new->chan = chan;
+	} else {
+		hvs = vsock_sk(sk)->trans;
+		hvs->chan = chan;
+	}
+
+	set_channel_read_mode(chan, HV_CALL_DIRECT);
+
+	/* Use the socket buffer sizes as hints for the VMBUS ring size. For
+	 * server side sockets, 'sk' is the parent socket and thus, this will
+	 * allow the child sockets to inherit the size from the parent. Keep
+	 * the mins to the default value and align to page size as per VMBUS
+	 * requirements.
+	 * For the max, the socket core library will limit the socket buffer
+	 * size that can be set by the user, but, since currently, the hv_sock
+	 * VMBUS ring buffer is physically contiguous allocation, restrict it
+	 * further.
+	 * Older versions of hv_sock host side code cannot handle bigger VMBUS
+	 * ring buffer size. Use the version number to limit the change to newer
+	 * versions.
+	 */
+	if (vmbus_proto_version < VERSION_WIN10_V5) {
+		sndbuf = RINGBUFFER_HVS_SND_SIZE;
+		rcvbuf = RINGBUFFER_HVS_RCV_SIZE;
+	} else {
+		sndbuf = max_t(int, sk->sk_sndbuf, RINGBUFFER_HVS_SND_SIZE);
+		sndbuf = min_t(int, sndbuf, RINGBUFFER_HVS_MAX_SIZE);
+		sndbuf = VMBUS_RING_SIZE(sndbuf);
+		rcvbuf = max_t(int, sk->sk_rcvbuf, RINGBUFFER_HVS_RCV_SIZE);
+		rcvbuf = min_t(int, rcvbuf, RINGBUFFER_HVS_MAX_SIZE);
+		rcvbuf = VMBUS_RING_SIZE(rcvbuf);
+	}
+
+	chan->max_pkt_size = HVS_MAX_PKT_SIZE;
+
+	ret = vmbus_open(chan, sndbuf, rcvbuf, NULL, 0, hvs_channel_cb,
+			 conn_from_host ? new : sk);
+	if (ret != 0) {
+		if (conn_from_host) {
+			hvs_new->chan = NULL;
+			sock_put(new);
+		} else {
+			hvs->chan = NULL;
+		}
+		goto out;
+	}
+
+	set_per_channel_state(chan, conn_from_host ? new : sk);
+
+	/* This reference will be dropped by hvs_close_connection(). */
+	sock_hold(conn_from_host ? new : sk);
+	vmbus_set_chn_rescind_callback(chan, hvs_close_connection);
+
+	/* Set the pending send size to max packet size to always get
+	 * notifications from the host when there is enough writable space.
+	 * The host is optimized to send notifications only when the pending
+	 * size boundary is crossed, and not always.
+	 */
+	hvs_set_channel_pending_send_size(chan);
+
+	if (conn_from_host) {
+		new->sk_state = TCP_ESTABLISHED;
+
+		hvs_new->vm_srv_id = *if_type;
+		hvs_new->host_srv_id = *if_instance;
+
+		vsock_insert_connected(vnew);
+
+		vsock_enqueue_accept(sk, new);
+	} else {
+		sk->sk_state = TCP_ESTABLISHED;
+		sk->sk_socket->state = SS_CONNECTED;
+
+		vsock_insert_connected(vsock_sk(sk));
+	}
+
+	sk->sk_state_change(sk);
+
+out:
+	/* Release refcnt obtained when we called vsock_find_bound_socket() */
+	sock_put(sk);
+
+	release_sock(sk);
+}
+
+static u32 hvs_get_local_cid(void)
+{
+	return VMADDR_CID_ANY;
+}
+
+static int hvs_sock_init(struct vsock_sock *vsk, struct vsock_sock *psk)
+{
+	struct hvsock *hvs;
+	struct sock *sk = sk_vsock(vsk);
+
+	hvs = kzalloc_obj(*hvs);
+	if (!hvs)
+		return -ENOMEM;
+
+	vsk->trans = hvs;
+	hvs->vsk = vsk;
+	sk->sk_sndbuf = RINGBUFFER_HVS_SND_SIZE;
+	sk->sk_rcvbuf = RINGBUFFER_HVS_RCV_SIZE;
+	return 0;
+}
+
+static int hvs_connect(struct vsock_sock *vsk)
+{
+	union hvs_service_id vm, host;
+	struct hvsock *h = vsk->trans;
+
+	vm.srv_id = srv_id_template;
+	vm.svm_port = vsk->local_addr.svm_port;
+	h->vm_srv_id = vm.srv_id;
+
+	host.srv_id = srv_id_template;
+	host.svm_port = vsk->remote_addr.svm_port;
+	h->host_srv_id = host.srv_id;
+
+	return vmbus_send_tl_connect_request(&h->vm_srv_id, &h->host_srv_id);
+}
+
+static void hvs_shutdown_lock_held(struct hvsock *hvs, int mode)
+{
+	struct vmpipe_proto_header hdr;
+
+	if (hvs->fin_sent || !hvs->chan)
+		return;
+
+	/* It can't fail: see hvs_channel_writable_bytes(). */
+	(void)__hvs_send_data(hvs->chan, &hdr, 0);
+	hvs->fin_sent = true;
+}
+
+static int hvs_shutdown(struct vsock_sock *vsk, int mode)
+{
+	if (!(mode & SEND_SHUTDOWN))
+		return 0;
+
+	hvs_shutdown_lock_held(vsk->trans, mode);
+	return 0;
+}
+
+static void hvs_close_timeout(struct work_struct *work)
+{
+	struct vsock_sock *vsk =
+		container_of(work, struct vsock_sock, close_work.work);
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_hold(sk);
+	lock_sock(sk);
+	if (!sock_flag(sk, SOCK_DONE))
+		hvs_do_close_lock_held(vsk, false);
+
+	vsk->close_work_scheduled = false;
+	release_sock(sk);
+	sock_put(sk);
+}
+
+/* Returns true, if it is safe to remove socket; false otherwise */
+static bool hvs_close_lock_held(struct vsock_sock *vsk)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	if (!(sk->sk_state == TCP_ESTABLISHED ||
+	      sk->sk_state == TCP_CLOSING))
+		return true;
+
+	if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
+		hvs_shutdown_lock_held(vsk->trans, SHUTDOWN_MASK);
+
+	if (sock_flag(sk, SOCK_DONE))
+		return true;
+
+	/* This reference will be dropped by the delayed close routine */
+	sock_hold(sk);
+	INIT_DELAYED_WORK(&vsk->close_work, hvs_close_timeout);
+	vsk->close_work_scheduled = true;
+	schedule_delayed_work(&vsk->close_work, HVS_CLOSE_TIMEOUT);
+	return false;
+}
+
+static void hvs_release(struct vsock_sock *vsk)
+{
+	bool remove_sock;
+
+	remove_sock = hvs_close_lock_held(vsk);
+	if (remove_sock)
+		vsock_remove_sock(vsk);
+}
+
+static void hvs_destruct(struct vsock_sock *vsk)
+{
+	struct hvsock *hvs = vsk->trans;
+	struct vmbus_channel *chan = hvs->chan;
+
+	if (chan)
+		vmbus_hvsock_device_unregister(chan);
+
+	kfree(hvs);
+	vsk->trans = NULL;
+}
+
+static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
+{
+	return -EOPNOTSUPP;
+}
+
+static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
+			     size_t len, int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+static int hvs_dgram_enqueue(struct vsock_sock *vsk,
+			     struct sockaddr_vm *remote, struct msghdr *msg,
+			     size_t dgram_len)
+{
+	return -EOPNOTSUPP;
+}
+
+static bool hvs_dgram_allow(struct vsock_sock *vsk, u32 cid, u32 port)
+{
+	return false;
+}
+
+static int hvs_update_recv_data(struct hvsock *hvs)
+{
+	struct hvs_recv_buf *recv_buf;
+	u32 pkt_len, payload_len;
+
+	pkt_len = hv_pkt_len(hvs->recv_desc);
+
+	if (pkt_len < HVS_HEADER_LEN)
+		return -EIO;
+
+	recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
+	payload_len = recv_buf->hdr.data_size;
+
+	if (payload_len > pkt_len - HVS_HEADER_LEN ||
+	    payload_len > HVS_MTU_SIZE)
+		return -EIO;
+
+	if (payload_len == 0)
+		WRITE_ONCE(hvs->vsk->peer_shutdown,
+			   READ_ONCE(hvs->vsk->peer_shutdown) |
+			   SEND_SHUTDOWN);
+
+	hvs->recv_data_len = payload_len;
+	hvs->recv_data_off = 0;
+
+	return 0;
+}
+
+static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
+				  size_t len, int flags)
+{
+	struct hvsock *hvs = vsk->trans;
+	bool need_refill = !hvs->recv_desc;
+	struct hvs_recv_buf *recv_buf;
+	u32 to_read;
+	int ret;
+
+	if (flags & MSG_PEEK)
+		return -EOPNOTSUPP;
+
+	if (need_refill) {
+		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
+		if (!hvs->recv_desc)
+			return -ENOBUFS;
+		ret = hvs_update_recv_data(hvs);
+		if (ret)
+			return ret;
+	}
+
+	recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
+	to_read = min_t(u32, len, hvs->recv_data_len);
+	ret = memcpy_to_msg(msg, recv_buf->data + hvs->recv_data_off, to_read);
+	if (ret != 0)
+		return ret;
+
+	hvs->recv_data_len -= to_read;
+	if (hvs->recv_data_len == 0) {
+		hvs->recv_desc = hv_pkt_iter_next(hvs->chan, hvs->recv_desc);
+		if (hvs->recv_desc) {
+			ret = hvs_update_recv_data(hvs);
+			if (ret)
+				return ret;
+		}
+	} else {
+		hvs->recv_data_off += to_read;
+	}
+
+	return to_read;
+}
+
+static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg,
+				  size_t len)
+{
+	struct hvsock *hvs = vsk->trans;
+	struct vmbus_channel *chan = hvs->chan;
+	struct hvs_send_buf *send_buf;
+	ssize_t to_write, max_writable;
+	ssize_t ret = 0;
+	ssize_t bytes_written = 0;
+
+	BUILD_BUG_ON(sizeof(*send_buf) != HV_HYP_PAGE_SIZE);
+
+	send_buf = kmalloc_obj(*send_buf);
+	if (!send_buf)
+		return -ENOMEM;
+
+	/* Reader(s) could be draining data from the channel as we write.
+	 * Maximize bandwidth, by iterating until the channel is found to be
+	 * full.
+	 */
+	while (len) {
+		max_writable = hvs_channel_writable_bytes(chan);
+		if (!max_writable)
+			break;
+		to_write = min_t(ssize_t, len, max_writable);
+		to_write = min_t(ssize_t, to_write, HVS_SEND_BUF_SIZE);
+		/* memcpy_from_msg is safe for loop as it advances the offsets
+		 * within the message iterator.
+		 */
+		ret = memcpy_from_msg(send_buf->data, msg, to_write);
+		if (ret < 0)
+			goto out;
+
+		ret = hvs_send_data(hvs->chan, send_buf, to_write);
+		if (ret < 0)
+			goto out;
+
+		bytes_written += to_write;
+		len -= to_write;
+	}
+out:
+	/* If any data has been sent, return that */
+	if (bytes_written)
+		ret = bytes_written;
+	kfree(send_buf);
+	return ret;
+}
+
+static s64 hvs_stream_has_data(struct vsock_sock *vsk)
+{
+	struct hvsock *hvs = vsk->trans;
+	s64 ret;
+
+	if (hvs->recv_data_len > 0)
+		return hvs->recv_data_len;
+
+	switch (hvs_channel_readable_payload(hvs->chan)) {
+	case 1:
+		if (hvs->recv_desc) {
+			/* Here hvs->recv_data_len is 0, so hvs->recv_desc must
+			 * be NULL unless it points to the 0-byte-payload FIN
+			 * packet or a malformed/short packet: see
+			 * hvs_update_recv_data().
+			 *
+			 * If hvs->recv_desc points to the FIN packet, here all
+			 * the payload has been dequeued and the peer_shutdown
+			 * flag is set, but hvs_channel_readable_payload() still
+			 * returns 1, because the VMBus ringbuffer's read_index
+			 * is not updated for the FIN packet:
+			 * hvs_stream_dequeue() -> hv_pkt_iter_next() updates
+			 * the cached priv_read_index but has no opportunity to
+			 * update the read_index in hv_pkt_iter_close() as
+			 * hvs_stream_has_data() returns 0 for the FIN packet,
+			 * so it won't get dequeued.
+			 *
+			 * In case hvs->recv_desc points to a malformed/short
+			 * packet, return -EIO.
+			 */
+			if (!(vsk->peer_shutdown & SEND_SHUTDOWN))
+				return -EIO;
+
+			return 0;
+		}
+
+		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
+		if (!hvs->recv_desc)
+			return -ENOBUFS;
+
+		ret = hvs_update_recv_data(hvs);
+		if (ret)
+			return ret;
+		return hvs->recv_data_len;
+	case 0:
+		WRITE_ONCE(vsk->peer_shutdown,
+			   READ_ONCE(vsk->peer_shutdown) | SEND_SHUTDOWN);
+		ret = 0;
+		break;
+	default: /* -1 */
+		ret = 0;
+		break;
+	}
+
+	return ret;
+}
+
+static s64 hvs_stream_has_space(struct vsock_sock *vsk)
+{
+	struct hvsock *hvs = vsk->trans;
+
+	return hvs_channel_writable_bytes(hvs->chan);
+}
+
+static u64 hvs_stream_rcvhiwat(struct vsock_sock *vsk)
+{
+	return HVS_MTU_SIZE + 1;
+}
+
+static bool hvs_stream_is_active(struct vsock_sock *vsk)
+{
+	struct hvsock *hvs = vsk->trans;
+
+	return hvs->chan != NULL;
+}
+
+static bool hvs_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port)
+{
+	if (!vsock_net_mode_global(vsk))
+		return false;
+
+	if (cid == VMADDR_CID_HOST)
+		return true;
+
+	return false;
+}
+
+static
+int hvs_notify_poll_in(struct vsock_sock *vsk, size_t target, bool *readable)
+{
+	struct hvsock *hvs = vsk->trans;
+
+	*readable = hvs_channel_readable(hvs->chan);
+	return 0;
+}
+
+static
+int hvs_notify_poll_out(struct vsock_sock *vsk, size_t target, bool *writable)
+{
+	*writable = hvs_stream_has_space(vsk) > 0;
+
+	return 0;
+}
+
+static
+int hvs_notify_recv_init(struct vsock_sock *vsk, size_t target,
+			 struct vsock_transport_recv_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_recv_pre_block(struct vsock_sock *vsk, size_t target,
+			      struct vsock_transport_recv_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_recv_pre_dequeue(struct vsock_sock *vsk, size_t target,
+				struct vsock_transport_recv_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_recv_post_dequeue(struct vsock_sock *vsk, size_t target,
+				 ssize_t copied, bool data_read,
+				 struct vsock_transport_recv_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_send_init(struct vsock_sock *vsk,
+			 struct vsock_transport_send_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_send_pre_block(struct vsock_sock *vsk,
+			      struct vsock_transport_send_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_send_pre_enqueue(struct vsock_sock *vsk,
+				struct vsock_transport_send_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_send_post_enqueue(struct vsock_sock *vsk, ssize_t written,
+				 struct vsock_transport_send_notify_data *d)
+{
+	return 0;
+}
+
+static
+int hvs_notify_set_rcvlowat(struct vsock_sock *vsk, int val)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct vsock_transport hvs_transport = {
+	.module                   = THIS_MODULE,
+
+	.get_local_cid            = hvs_get_local_cid,
+
+	.init                     = hvs_sock_init,
+	.destruct                 = hvs_destruct,
+	.release                  = hvs_release,
+	.connect                  = hvs_connect,
+	.shutdown                 = hvs_shutdown,
+
+	.dgram_bind               = hvs_dgram_bind,
+	.dgram_dequeue            = hvs_dgram_dequeue,
+	.dgram_enqueue            = hvs_dgram_enqueue,
+	.dgram_allow              = hvs_dgram_allow,
+
+	.stream_dequeue           = hvs_stream_dequeue,
+	.stream_enqueue           = hvs_stream_enqueue,
+	.stream_has_data          = hvs_stream_has_data,
+	.stream_has_space         = hvs_stream_has_space,
+	.stream_rcvhiwat          = hvs_stream_rcvhiwat,
+	.stream_is_active         = hvs_stream_is_active,
+	.stream_allow             = hvs_stream_allow,
+
+	.notify_poll_in           = hvs_notify_poll_in,
+	.notify_poll_out          = hvs_notify_poll_out,
+	.notify_recv_init         = hvs_notify_recv_init,
+	.notify_recv_pre_block    = hvs_notify_recv_pre_block,
+	.notify_recv_pre_dequeue  = hvs_notify_recv_pre_dequeue,
+	.notify_recv_post_dequeue = hvs_notify_recv_post_dequeue,
+	.notify_send_init         = hvs_notify_send_init,
+	.notify_send_pre_block    = hvs_notify_send_pre_block,
+	.notify_send_pre_enqueue  = hvs_notify_send_pre_enqueue,
+	.notify_send_post_enqueue = hvs_notify_send_post_enqueue,
+
+	.notify_set_rcvlowat      = hvs_notify_set_rcvlowat
+};
+
+static bool hvs_check_transport(struct vsock_sock *vsk)
+{
+	return vsk->transport == &hvs_transport;
+}
+
+static int hvs_probe(struct hv_device *hdev,
+		     const struct hv_vmbus_device_id *dev_id)
+{
+	struct vmbus_channel *chan = hdev->channel;
+
+	hvs_open_connection(chan);
+
+	/* Always return success to suppress the unnecessary error message
+	 * in vmbus_probe(): on error the host will rescind the device in
+	 * 30 seconds and we can do cleanup at that time in
+	 * vmbus_onoffer_rescind().
+	 */
+	return 0;
+}
+
+static void hvs_remove(struct hv_device *hdev)
+{
+	struct vmbus_channel *chan = hdev->channel;
+
+	vmbus_close(chan);
+}
+
+/* hv_sock connections can not persist across hibernation, and all the hv_sock
+ * channels are forced to be rescinded before hibernation: see
+ * vmbus_bus_suspend(). Here the dummy hvs_suspend() and hvs_resume()
+ * are only needed because hibernation requires that every vmbus device's
+ * driver should have a .suspend and .resume callback: see vmbus_suspend().
+ */
+static int hvs_suspend(struct hv_device *hv_dev)
+{
+	/* Dummy */
+	return 0;
+}
+
+static int hvs_resume(struct hv_device *dev)
+{
+	/* Dummy */
+	return 0;
+}
+
+/* This isn't really used. See vmbus_match() and vmbus_probe() */
+static const struct hv_vmbus_device_id id_table[] = {
+	{},
+};
+
+static struct hv_driver hvs_drv = {
+	.name		= "hv_sock",
+	.hvsock		= true,
+	.id_table	= id_table,
+	.probe		= hvs_probe,
+	.remove		= hvs_remove,
+	.suspend	= hvs_suspend,
+	.resume		= hvs_resume,
+};
+
+static int __init hvs_init(void)
+{
+	int ret;
+
+	if (vmbus_proto_version < VERSION_WIN10)
+		return -ENODEV;
+
+	ret = vmbus_driver_register(&hvs_drv);
+	if (ret != 0)
+		return ret;
+
+	ret = vsock_core_register(&hvs_transport, VSOCK_TRANSPORT_F_G2H);
+	if (ret) {
+		vmbus_driver_unregister(&hvs_drv);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit hvs_exit(void)
+{
+	vsock_core_unregister(&hvs_transport);
+	vmbus_driver_unregister(&hvs_drv);
+}
+
+module_init(hvs_init);
+module_exit(hvs_exit);
+
+MODULE_DESCRIPTION("Hyper-V Sockets");
+MODULE_VERSION("1.0.0");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NETPROTO(PF_VSOCK);
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
new file mode 100644
index 000000000..96c9fe8d3
--- /dev/null
+++ b/net/vmw_vsock/virtio_transport.c
@@ -0,0 +1,989 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * virtio transport for vsock
+ *
+ * Copyright (C) 2013-2015 Red Hat, Inc.
+ * Author: Asias He <asias@redhat.com>
+ *         Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * Some of the code is take from Gerd Hoffmann <kraxel@redhat.com>'s
+ * early virtio-vsock proof-of-concept bits.
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/atomic.h>
+#include <linux/virtio.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_vsock.h>
+#include <linux/dma-mapping.h>
+#include <net/sock.h>
+#include <linux/mutex.h>
+#include <net/af_vsock.h>
+
+static struct workqueue_struct *virtio_vsock_workqueue;
+static struct virtio_vsock __rcu *the_virtio_vsock;
+static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
+static struct virtio_transport virtio_transport; /* forward declaration */
+
+struct virtio_vsock {
+	struct virtio_device *vdev;
+	struct virtqueue *vqs[VSOCK_VQ_MAX];
+
+	/* Virtqueue processing is deferred to a workqueue */
+	struct work_struct tx_work;
+	struct work_struct rx_work;
+	struct work_struct event_work;
+
+	/* The following fields are protected by tx_lock.  vqs[VSOCK_VQ_TX]
+	 * must be accessed with tx_lock held.
+	 */
+	struct mutex tx_lock;
+	bool tx_run;
+
+	struct work_struct send_pkt_work;
+	struct sk_buff_head send_pkt_queue;
+
+	atomic_t queued_replies;
+
+	/* The following fields are protected by rx_lock.  vqs[VSOCK_VQ_RX]
+	 * must be accessed with rx_lock held.
+	 */
+	struct mutex rx_lock;
+	bool rx_run;
+	int rx_buf_nr;
+	int rx_buf_max_nr;
+
+	u32 guest_cid;
+	bool seqpacket_allow;
+
+	/* These fields are used only in tx path in function
+	 * 'virtio_transport_send_pkt_work()', so to save
+	 * stack space in it, place both of them here. Each
+	 * pointer from 'out_sgs' points to the corresponding
+	 * element in 'out_bufs' - this is initialized in
+	 * 'virtio_vsock_probe()'. Both fields are protected
+	 * by 'tx_lock'. +1 is needed for packet header.
+	 */
+	struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1];
+	struct scatterlist out_bufs[MAX_SKB_FRAGS + 1];
+
+	/* The following fields are protected by event_lock.
+	 * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
+	 */
+	struct mutex event_lock;
+	bool event_run;
+	__dma_from_device_group_begin();
+	struct virtio_vsock_event event_list[8];
+	__dma_from_device_group_end();
+};
+
+static u32 virtio_transport_get_local_cid(void)
+{
+	struct virtio_vsock *vsock;
+	u32 ret;
+
+	rcu_read_lock();
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (!vsock) {
+		ret = VMADDR_CID_ANY;
+		goto out_rcu;
+	}
+
+	ret = vsock->guest_cid;
+out_rcu:
+	rcu_read_unlock();
+	return ret;
+}
+
+/* Caller need to hold vsock->tx_lock on vq */
+static int virtio_transport_send_skb(struct sk_buff *skb, struct virtqueue *vq,
+				     struct virtio_vsock *vsock, gfp_t gfp)
+{
+	int ret, in_sg = 0, out_sg = 0;
+	struct scatterlist **sgs;
+
+	sgs = vsock->out_sgs;
+	sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
+		    sizeof(*virtio_vsock_hdr(skb)));
+	out_sg++;
+
+	if (!skb_is_nonlinear(skb)) {
+		if (skb->len > 0) {
+			sg_init_one(sgs[out_sg], skb->data, skb->len);
+			out_sg++;
+		}
+	} else {
+		struct skb_shared_info *si;
+		int i;
+
+		/* If skb is nonlinear, then its buffer must contain
+		 * only header and nothing more. Data is stored in
+		 * the fragged part.
+		 */
+		WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));
+
+		si = skb_shinfo(skb);
+
+		for (i = 0; i < si->nr_frags; i++) {
+			skb_frag_t *skb_frag = &si->frags[i];
+			void *va;
+
+			/* We will use 'page_to_virt()' for the userspace page
+			 * here, because virtio or dma-mapping layers will call
+			 * 'virt_to_phys()' later to fill the buffer descriptor.
+			 * We don't touch memory at "virtual" address of this page.
+			 */
+			va = page_to_virt(skb_frag_page(skb_frag));
+			sg_init_one(sgs[out_sg],
+				    va + skb_frag_off(skb_frag),
+				    skb_frag_size(skb_frag));
+			out_sg++;
+		}
+	}
+
+	ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, gfp);
+	/* Usually this means that there is no more space available in
+	 * the vq
+	 */
+	if (ret < 0)
+		return ret;
+
+	virtio_transport_deliver_tap_pkt(skb);
+	return 0;
+}
+
+static void
+virtio_transport_send_pkt_work(struct work_struct *work)
+{
+	struct virtio_vsock *vsock =
+		container_of(work, struct virtio_vsock, send_pkt_work);
+	struct virtqueue *vq;
+	bool added = false;
+	bool restart_rx = false;
+
+	mutex_lock(&vsock->tx_lock);
+
+	if (!vsock->tx_run)
+		goto out;
+
+	vq = vsock->vqs[VSOCK_VQ_TX];
+
+	for (;;) {
+		struct sk_buff *skb;
+		bool reply;
+		int ret;
+
+		skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
+		if (!skb)
+			break;
+
+		reply = virtio_vsock_skb_reply(skb);
+
+		ret = virtio_transport_send_skb(skb, vq, vsock, GFP_KERNEL);
+		if (ret < 0) {
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
+			break;
+		}
+
+		if (reply) {
+			struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
+			int val;
+
+			val = atomic_dec_return(&vsock->queued_replies);
+
+			/* Do we now have resources to resume rx processing? */
+			if (val + 1 == virtqueue_get_vring_size(rx_vq))
+				restart_rx = true;
+		}
+
+		added = true;
+	}
+
+	if (added)
+		virtqueue_kick(vq);
+
+out:
+	mutex_unlock(&vsock->tx_lock);
+
+	if (restart_rx)
+		queue_work(virtio_vsock_workqueue, &vsock->rx_work);
+}
+
+/* Caller need to hold RCU for vsock.
+ * Returns 0 if the packet is successfully put on the vq.
+ */
+static int virtio_transport_send_skb_fast_path(struct virtio_vsock *vsock, struct sk_buff *skb)
+{
+	struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];
+	int ret;
+
+	/* Inside RCU, can't sleep! */
+	ret = mutex_trylock(&vsock->tx_lock);
+	if (unlikely(ret == 0))
+		return -EBUSY;
+
+	ret = virtio_transport_send_skb(skb, vq, vsock, GFP_ATOMIC);
+	if (ret == 0)
+		virtqueue_kick(vq);
+
+	mutex_unlock(&vsock->tx_lock);
+
+	return ret;
+}
+
+static int
+virtio_transport_send_pkt(struct sk_buff *skb, struct net *net)
+{
+	struct virtio_vsock_hdr *hdr;
+	struct virtio_vsock *vsock;
+	int len = skb->len;
+
+	hdr = virtio_vsock_hdr(skb);
+
+	rcu_read_lock();
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (!vsock) {
+		kfree_skb(skb);
+		len = -ENODEV;
+		goto out_rcu;
+	}
+
+	if (le64_to_cpu(hdr->dst_cid) == vsock->guest_cid) {
+		kfree_skb(skb);
+		len = -ENODEV;
+		goto out_rcu;
+	}
+
+	/* If send_pkt_queue is empty, we can safely bypass this queue
+	 * because packet order is maintained and (try) to put the packet
+	 * on the virtqueue using virtio_transport_send_skb_fast_path.
+	 * If this fails we simply put the packet on the intermediate
+	 * queue and schedule the worker.
+	 */
+	if (!skb_queue_empty_lockless(&vsock->send_pkt_queue) ||
+	    virtio_transport_send_skb_fast_path(vsock, skb)) {
+		if (virtio_vsock_skb_reply(skb))
+			atomic_inc(&vsock->queued_replies);
+
+		virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
+		queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+	}
+
+out_rcu:
+	rcu_read_unlock();
+	return len;
+}
+
+static int
+virtio_transport_cancel_pkt(struct vsock_sock *vsk)
+{
+	struct virtio_vsock *vsock;
+	int cnt = 0, ret;
+
+	rcu_read_lock();
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (!vsock) {
+		ret = -ENODEV;
+		goto out_rcu;
+	}
+
+	cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
+
+	if (cnt) {
+		struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
+		int new_cnt;
+
+		new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
+		if (new_cnt + cnt >= virtqueue_get_vring_size(rx_vq) &&
+		    new_cnt < virtqueue_get_vring_size(rx_vq))
+			queue_work(virtio_vsock_workqueue, &vsock->rx_work);
+	}
+
+	ret = 0;
+
+out_rcu:
+	rcu_read_unlock();
+	return ret;
+}
+
+static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
+{
+	int total_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
+	struct scatterlist pkt, *p;
+	struct virtqueue *vq;
+	struct sk_buff *skb;
+	int ret;
+
+	vq = vsock->vqs[VSOCK_VQ_RX];
+
+	do {
+		skb = virtio_vsock_alloc_linear_skb(total_len, GFP_KERNEL);
+		if (!skb)
+			break;
+
+		memset(skb->head, 0, VIRTIO_VSOCK_SKB_HEADROOM);
+		sg_init_one(&pkt, virtio_vsock_hdr(skb), total_len);
+		p = &pkt;
+		ret = virtqueue_add_sgs(vq, &p, 0, 1, skb, GFP_KERNEL);
+		if (ret < 0) {
+			kfree_skb(skb);
+			break;
+		}
+
+		vsock->rx_buf_nr++;
+	} while (vq->num_free);
+	if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
+		vsock->rx_buf_max_nr = vsock->rx_buf_nr;
+	virtqueue_kick(vq);
+}
+
+static void virtio_transport_tx_work(struct work_struct *work)
+{
+	struct virtio_vsock *vsock =
+		container_of(work, struct virtio_vsock, tx_work);
+	struct virtqueue *vq;
+	bool added = false;
+
+	mutex_lock(&vsock->tx_lock);
+
+	if (!vsock->tx_run)
+		goto out;
+
+	vq = vsock->vqs[VSOCK_VQ_TX];
+
+	do {
+		struct sk_buff *skb;
+		unsigned int len;
+
+		virtqueue_disable_cb(vq);
+		while ((skb = virtqueue_get_buf(vq, &len)) != NULL) {
+			virtio_transport_consume_skb_sent(skb, true);
+			added = true;
+		}
+	} while (!virtqueue_enable_cb(vq));
+
+out:
+	mutex_unlock(&vsock->tx_lock);
+
+	if (added)
+		queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+}
+
+/* Is there space left for replies to rx packets? */
+static bool virtio_transport_more_replies(struct virtio_vsock *vsock)
+{
+	struct virtqueue *vq = vsock->vqs[VSOCK_VQ_RX];
+	int val;
+
+	smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
+	val = atomic_read(&vsock->queued_replies);
+
+	return val < virtqueue_get_vring_size(vq);
+}
+
+/* event_lock must be held */
+static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
+				       struct virtio_vsock_event *event)
+{
+	struct scatterlist sg;
+	struct virtqueue *vq;
+
+	vq = vsock->vqs[VSOCK_VQ_EVENT];
+
+	sg_init_one(&sg, event, sizeof(*event));
+
+	return virtqueue_add_inbuf_cache_clean(vq, &sg, 1, event, GFP_KERNEL);
+}
+
+/* event_lock must be held */
+static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
+{
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(vsock->event_list); i++) {
+		struct virtio_vsock_event *event = &vsock->event_list[i];
+
+		virtio_vsock_event_fill_one(vsock, event);
+	}
+
+	virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
+}
+
+static void virtio_vsock_reset_sock(struct sock *sk)
+{
+	/* vmci_transport.c doesn't take sk_lock here either.  At least we're
+	 * under vsock_table_lock so the sock cannot disappear while we're
+	 * executing.
+	 */
+
+	sk->sk_state = TCP_CLOSE;
+	sk->sk_err = ECONNRESET;
+	sk_error_report(sk);
+}
+
+static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
+{
+	struct virtio_device *vdev = vsock->vdev;
+	__le64 guest_cid;
+
+	vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
+			  &guest_cid, sizeof(guest_cid));
+	vsock->guest_cid = le64_to_cpu(guest_cid);
+}
+
+/* event_lock must be held */
+static void virtio_vsock_event_handle(struct virtio_vsock *vsock,
+				      struct virtio_vsock_event *event)
+{
+	switch (le32_to_cpu(event->id)) {
+	case VIRTIO_VSOCK_EVENT_TRANSPORT_RESET:
+		virtio_vsock_update_guest_cid(vsock);
+		vsock_for_each_connected_socket(&virtio_transport.transport,
+						virtio_vsock_reset_sock);
+		break;
+	}
+}
+
+static void virtio_transport_event_work(struct work_struct *work)
+{
+	struct virtio_vsock *vsock =
+		container_of(work, struct virtio_vsock, event_work);
+	struct virtqueue *vq;
+
+	mutex_lock(&vsock->event_lock);
+
+	if (!vsock->event_run)
+		goto out;
+
+	vq = vsock->vqs[VSOCK_VQ_EVENT];
+
+	do {
+		struct virtio_vsock_event *event;
+		unsigned int len;
+
+		virtqueue_disable_cb(vq);
+		while ((event = virtqueue_get_buf(vq, &len)) != NULL) {
+			if (len == sizeof(*event))
+				virtio_vsock_event_handle(vsock, event);
+
+			virtio_vsock_event_fill_one(vsock, event);
+		}
+	} while (!virtqueue_enable_cb(vq));
+
+	virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
+out:
+	mutex_unlock(&vsock->event_lock);
+}
+
+static void virtio_vsock_event_done(struct virtqueue *vq)
+{
+	struct virtio_vsock *vsock = vq->vdev->priv;
+
+	if (!vsock)
+		return;
+	queue_work(virtio_vsock_workqueue, &vsock->event_work);
+}
+
+static void virtio_vsock_tx_done(struct virtqueue *vq)
+{
+	struct virtio_vsock *vsock = vq->vdev->priv;
+
+	if (!vsock)
+		return;
+	queue_work(virtio_vsock_workqueue, &vsock->tx_work);
+}
+
+static void virtio_vsock_rx_done(struct virtqueue *vq)
+{
+	struct virtio_vsock *vsock = vq->vdev->priv;
+
+	if (!vsock)
+		return;
+	queue_work(virtio_vsock_workqueue, &vsock->rx_work);
+}
+
+static bool virtio_transport_can_msgzerocopy(int bufs_num)
+{
+	struct virtio_vsock *vsock;
+	bool res = false;
+
+	rcu_read_lock();
+
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (vsock) {
+		struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];
+
+		/* Check that tx queue is large enough to keep whole
+		 * data to send. This is needed, because when there is
+		 * not enough free space in the queue, current skb to
+		 * send will be reinserted to the head of tx list of
+		 * the socket to retry transmission later, so if skb
+		 * is bigger than whole queue, it will be reinserted
+		 * again and again, thus blocking other skbs to be sent.
+		 * Each page of the user provided buffer will be added
+		 * as a single buffer to the tx virtqueue, so compare
+		 * number of pages against maximum capacity of the queue.
+		 */
+		if (bufs_num <= vq->num_max)
+			res = true;
+	}
+
+	rcu_read_unlock();
+
+	return res;
+}
+
+static bool virtio_transport_msgzerocopy_allow(void)
+{
+	return true;
+}
+
+bool virtio_transport_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port)
+{
+	return vsock_net_mode_global(vsk);
+}
+
+static bool virtio_transport_seqpacket_allow(struct vsock_sock *vsk,
+					     u32 remote_cid);
+
+static bool virtio_transport_has_remote_cid(struct vsock_sock *vsk, u32 cid)
+{
+	/* The CID could be implemented by the host. Always assume it is. */
+	return true;
+}
+
+static struct virtio_transport virtio_transport = {
+	.transport = {
+		.module                   = THIS_MODULE,
+
+		.get_local_cid            = virtio_transport_get_local_cid,
+		.has_remote_cid           = virtio_transport_has_remote_cid,
+
+		.init                     = virtio_transport_do_socket_init,
+		.destruct                 = virtio_transport_destruct,
+		.release                  = virtio_transport_release,
+		.connect                  = virtio_transport_connect,
+		.shutdown                 = virtio_transport_shutdown,
+		.cancel_pkt               = virtio_transport_cancel_pkt,
+
+		.dgram_bind               = virtio_transport_dgram_bind,
+		.dgram_dequeue            = virtio_transport_dgram_dequeue,
+		.dgram_enqueue            = virtio_transport_dgram_enqueue,
+		.dgram_allow              = virtio_transport_dgram_allow,
+
+		.stream_dequeue           = virtio_transport_stream_dequeue,
+		.stream_enqueue           = virtio_transport_stream_enqueue,
+		.stream_has_data          = virtio_transport_stream_has_data,
+		.stream_has_space         = virtio_transport_stream_has_space,
+		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
+		.stream_is_active         = virtio_transport_stream_is_active,
+		.stream_allow             = virtio_transport_stream_allow,
+
+		.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
+		.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
+		.seqpacket_allow          = virtio_transport_seqpacket_allow,
+		.seqpacket_has_data       = virtio_transport_seqpacket_has_data,
+
+		.msgzerocopy_allow        = virtio_transport_msgzerocopy_allow,
+
+		.notify_poll_in           = virtio_transport_notify_poll_in,
+		.notify_poll_out          = virtio_transport_notify_poll_out,
+		.notify_recv_init         = virtio_transport_notify_recv_init,
+		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
+		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
+		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
+		.notify_send_init         = virtio_transport_notify_send_init,
+		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
+		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
+		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
+		.notify_buffer_size       = virtio_transport_notify_buffer_size,
+		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
+
+		.unsent_bytes             = virtio_transport_unsent_bytes,
+
+		.read_skb = virtio_transport_read_skb,
+	},
+
+	.send_pkt = virtio_transport_send_pkt,
+	.can_msgzerocopy = virtio_transport_can_msgzerocopy,
+};
+
+static bool
+virtio_transport_seqpacket_allow(struct vsock_sock *vsk, u32 remote_cid)
+{
+	struct virtio_vsock *vsock;
+	bool seqpacket_allow;
+
+	if (!vsock_net_mode_global(vsk))
+		return false;
+
+	seqpacket_allow = false;
+	rcu_read_lock();
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (vsock)
+		seqpacket_allow = vsock->seqpacket_allow;
+	rcu_read_unlock();
+
+	return seqpacket_allow;
+}
+
+static void virtio_transport_rx_work(struct work_struct *work)
+{
+	struct virtio_vsock *vsock =
+		container_of(work, struct virtio_vsock, rx_work);
+	struct virtqueue *vq;
+
+	mutex_lock(&vsock->rx_lock);
+
+	if (!vsock->rx_run)
+		goto out_nofill;
+
+	vq = vsock->vqs[VSOCK_VQ_RX];
+
+	do {
+		virtqueue_disable_cb(vq);
+		for (;;) {
+			unsigned int len, payload_len;
+			struct virtio_vsock_hdr *hdr;
+			struct sk_buff *skb;
+
+			if (!virtio_transport_more_replies(vsock)) {
+				/* Stop rx until the device processes already
+				 * pending replies.  Leave rx virtqueue
+				 * callbacks disabled.
+				 */
+				goto out;
+			}
+
+			skb = virtqueue_get_buf(vq, &len);
+			if (!skb)
+				break;
+
+			vsock->rx_buf_nr--;
+
+			/* Drop short/long packets */
+			if (unlikely(len < sizeof(*hdr) ||
+				     len > virtio_vsock_skb_len(skb))) {
+				kfree_skb(skb);
+				continue;
+			}
+
+			hdr = virtio_vsock_hdr(skb);
+			payload_len = le32_to_cpu(hdr->len);
+			if (unlikely(payload_len > len - sizeof(*hdr))) {
+				kfree_skb(skb);
+				continue;
+			}
+
+			if (payload_len)
+				virtio_vsock_skb_put(skb, payload_len);
+
+			virtio_transport_deliver_tap_pkt(skb);
+
+			/* Force virtio-transport into global mode since it
+			 * does not yet support local-mode namespacing.
+			 */
+			virtio_transport_recv_pkt(&virtio_transport, skb, NULL);
+		}
+	} while (!virtqueue_enable_cb(vq));
+
+out:
+	if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
+		virtio_vsock_rx_fill(vsock);
+out_nofill:
+	mutex_unlock(&vsock->rx_lock);
+}
+
+static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
+{
+	struct virtio_device *vdev = vsock->vdev;
+	struct virtqueue_info vqs_info[] = {
+		{ "rx", virtio_vsock_rx_done },
+		{ "tx", virtio_vsock_tx_done },
+		{ "event", virtio_vsock_event_done },
+	};
+	int ret;
+
+	mutex_lock(&vsock->rx_lock);
+	vsock->rx_buf_nr = 0;
+	vsock->rx_buf_max_nr = 0;
+	mutex_unlock(&vsock->rx_lock);
+
+	atomic_set(&vsock->queued_replies, 0);
+
+	ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, vqs_info, NULL);
+	if (ret < 0)
+		return ret;
+
+	virtio_vsock_update_guest_cid(vsock);
+
+	virtio_device_ready(vdev);
+
+	return 0;
+}
+
+static void virtio_vsock_vqs_start(struct virtio_vsock *vsock)
+{
+	mutex_lock(&vsock->tx_lock);
+	vsock->tx_run = true;
+	mutex_unlock(&vsock->tx_lock);
+
+	mutex_lock(&vsock->rx_lock);
+	virtio_vsock_rx_fill(vsock);
+	vsock->rx_run = true;
+	mutex_unlock(&vsock->rx_lock);
+
+	mutex_lock(&vsock->event_lock);
+	virtio_vsock_event_fill(vsock);
+	vsock->event_run = true;
+	mutex_unlock(&vsock->event_lock);
+
+	/* virtio_transport_send_pkt() can queue packets once
+	 * the_virtio_vsock is set, but they won't be processed until
+	 * vsock->tx_run is set to true. We queue vsock->send_pkt_work
+	 * when initialization finishes to send those packets queued
+	 * earlier.
+	 * We don't need to queue the other workers (rx, event) because
+	 * as long as we don't fill the queues with empty buffers, the
+	 * host can't send us any notification.
+	 */
+	queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+}
+
+static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
+{
+	struct virtio_device *vdev = vsock->vdev;
+	struct sk_buff *skb;
+
+	/* Reset all connected sockets when the VQs disappear */
+	vsock_for_each_connected_socket(&virtio_transport.transport,
+					virtio_vsock_reset_sock);
+
+	/* Stop all work handlers to make sure no one is accessing the device,
+	 * so we can safely call virtio_reset_device().
+	 */
+	mutex_lock(&vsock->rx_lock);
+	vsock->rx_run = false;
+	mutex_unlock(&vsock->rx_lock);
+
+	mutex_lock(&vsock->tx_lock);
+	vsock->tx_run = false;
+	mutex_unlock(&vsock->tx_lock);
+
+	mutex_lock(&vsock->event_lock);
+	vsock->event_run = false;
+	mutex_unlock(&vsock->event_lock);
+
+	/* Flush all device writes and interrupts, device will not use any
+	 * more buffers.
+	 */
+	virtio_reset_device(vdev);
+
+	mutex_lock(&vsock->rx_lock);
+	while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
+		kfree_skb(skb);
+	mutex_unlock(&vsock->rx_lock);
+
+	mutex_lock(&vsock->tx_lock);
+	while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
+		kfree_skb(skb);
+	mutex_unlock(&vsock->tx_lock);
+
+	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
+
+	/* Delete virtqueues and flush outstanding callbacks if any */
+	vdev->config->del_vqs(vdev);
+}
+
+static int virtio_vsock_probe(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = NULL;
+	int ret;
+	int i;
+
+	ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
+	if (ret)
+		return ret;
+
+	/* Only one virtio-vsock device per guest is supported */
+	if (rcu_dereference_protected(the_virtio_vsock,
+				lockdep_is_held(&the_virtio_vsock_mutex))) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	vsock = kzalloc_obj(*vsock);
+	if (!vsock) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	vsock->vdev = vdev;
+
+
+	mutex_init(&vsock->tx_lock);
+	mutex_init(&vsock->rx_lock);
+	mutex_init(&vsock->event_lock);
+	skb_queue_head_init(&vsock->send_pkt_queue);
+	INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
+	INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
+	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
+	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
+
+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
+		vsock->seqpacket_allow = true;
+
+	vdev->priv = vsock;
+
+	ret = virtio_vsock_vqs_init(vsock);
+	if (ret < 0)
+		goto out;
+
+	for (i = 0; i < ARRAY_SIZE(vsock->out_sgs); i++)
+		vsock->out_sgs[i] = &vsock->out_bufs[i];
+
+	rcu_assign_pointer(the_virtio_vsock, vsock);
+	virtio_vsock_vqs_start(vsock);
+
+	mutex_unlock(&the_virtio_vsock_mutex);
+
+	return 0;
+
+out:
+	kfree(vsock);
+	mutex_unlock(&the_virtio_vsock_mutex);
+	return ret;
+}
+
+static void virtio_vsock_remove(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = vdev->priv;
+
+	mutex_lock(&the_virtio_vsock_mutex);
+
+	vdev->priv = NULL;
+	rcu_assign_pointer(the_virtio_vsock, NULL);
+	synchronize_rcu();
+
+	virtio_vsock_vqs_del(vsock);
+
+	/* Other works can be queued before 'config->del_vqs()', so we flush
+	 * all works before to free the vsock object to avoid use after free.
+	 */
+	flush_work(&vsock->rx_work);
+	flush_work(&vsock->tx_work);
+	flush_work(&vsock->event_work);
+	flush_work(&vsock->send_pkt_work);
+
+	mutex_unlock(&the_virtio_vsock_mutex);
+
+	kfree(vsock);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_vsock_freeze(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = vdev->priv;
+
+	mutex_lock(&the_virtio_vsock_mutex);
+
+	rcu_assign_pointer(the_virtio_vsock, NULL);
+	synchronize_rcu();
+
+	virtio_vsock_vqs_del(vsock);
+
+	mutex_unlock(&the_virtio_vsock_mutex);
+
+	return 0;
+}
+
+static int virtio_vsock_restore(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = vdev->priv;
+	int ret;
+
+	mutex_lock(&the_virtio_vsock_mutex);
+
+	/* Only one virtio-vsock device per guest is supported */
+	if (rcu_dereference_protected(the_virtio_vsock,
+				lockdep_is_held(&the_virtio_vsock_mutex))) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	ret = virtio_vsock_vqs_init(vsock);
+	if (ret < 0)
+		goto out;
+
+	rcu_assign_pointer(the_virtio_vsock, vsock);
+	virtio_vsock_vqs_start(vsock);
+
+out:
+	mutex_unlock(&the_virtio_vsock_mutex);
+	return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static unsigned int features[] = {
+	VIRTIO_VSOCK_F_SEQPACKET
+};
+
+static struct virtio_driver virtio_vsock_driver = {
+	.feature_table = features,
+	.feature_table_size = ARRAY_SIZE(features),
+	.driver.name = KBUILD_MODNAME,
+	.id_table = id_table,
+	.probe = virtio_vsock_probe,
+	.remove = virtio_vsock_remove,
+#ifdef CONFIG_PM_SLEEP
+	.freeze = virtio_vsock_freeze,
+	.restore = virtio_vsock_restore,
+#endif
+};
+
+static int __init virtio_vsock_init(void)
+{
+	int ret;
+
+	virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", WQ_PERCPU, 0);
+	if (!virtio_vsock_workqueue)
+		return -ENOMEM;
+
+	ret = vsock_core_register(&virtio_transport.transport,
+				  VSOCK_TRANSPORT_F_G2H);
+	if (ret)
+		goto out_wq;
+
+	ret = register_virtio_driver(&virtio_vsock_driver);
+	if (ret)
+		goto out_vci;
+
+	return 0;
+
+out_vci:
+	vsock_core_unregister(&virtio_transport.transport);
+out_wq:
+	destroy_workqueue(virtio_vsock_workqueue);
+	return ret;
+}
+
+static void __exit virtio_vsock_exit(void)
+{
+	unregister_virtio_driver(&virtio_vsock_driver);
+	vsock_core_unregister(&virtio_transport.transport);
+	destroy_workqueue(virtio_vsock_workqueue);
+}
+
+module_init(virtio_vsock_init);
+module_exit(virtio_vsock_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Asias He");
+MODULE_DESCRIPTION("virtio transport for vsock");
+MODULE_DEVICE_TABLE(virtio, id_table);
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
new file mode 100644
index 000000000..88df82364
--- /dev/null
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -0,0 +1,1989 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * common code for virtio vsock
+ *
+ * Copyright (C) 2013-2015 Red Hat, Inc.
+ * Author: Asias He <asias@redhat.com>
+ *         Stefan Hajnoczi <stefanha@redhat.com>
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/sched/signal.h>
+#include <linux/ctype.h>
+#include <linux/list.h>
+#include <linux/virtio_vsock.h>
+#include <uapi/linux/vsockmon.h>
+
+#include <net/sock.h>
+#include <net/af_vsock.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/vsock_virtio_transport_common.h>
+
+/* How long to wait for graceful shutdown of a connection */
+#define VSOCK_CLOSE_TIMEOUT (8 * HZ)
+
+/* Threshold for detecting small packets to copy */
+#define GOOD_COPY_LEN  128
+
+/* Max payload that can be collapsed into a single linear skb, using the same
+ * allocation threshold as virtio_vsock_alloc_skb() to avoid adding pressure
+ * on the page allocator.
+ */
+#define MAX_COLLAPSE_LEN \
+	SKB_MAX_ORDER(VIRTIO_VSOCK_SKB_HEADROOM, PAGE_ALLOC_COSTLY_ORDER)
+
+static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
+					       bool cancel_timeout);
+static s64 virtio_transport_has_space(struct virtio_vsock_sock *vvs);
+
+static const struct virtio_transport *
+virtio_transport_get_ops(struct vsock_sock *vsk)
+{
+	const struct vsock_transport *t = vsock_core_get_transport(vsk);
+
+	if (WARN_ON(!t))
+		return NULL;
+
+	return container_of(t, struct virtio_transport, transport);
+}
+
+static bool virtio_transport_can_zcopy(const struct virtio_transport *t_ops,
+				       struct virtio_vsock_pkt_info *info,
+				       size_t pkt_len)
+{
+	struct iov_iter *iov_iter;
+
+	if (!info->msg)
+		return false;
+
+	iov_iter = &info->msg->msg_iter;
+
+	if (iov_iter->iov_offset)
+		return false;
+
+	/* We can't send whole iov. */
+	if (iov_iter->count > pkt_len)
+		return false;
+
+	/* Check that transport can send data in zerocopy mode. */
+	if (t_ops->can_msgzerocopy) {
+		int pages_to_send = iov_iter_npages(iov_iter, MAX_SKB_FRAGS);
+
+		/* +1 is for packet header. */
+		return t_ops->can_msgzerocopy(pages_to_send + 1);
+	}
+
+	return true;
+}
+
+static int virtio_transport_fill_skb(struct sk_buff *skb,
+				     struct virtio_vsock_pkt_info *info,
+				     size_t len,
+				     bool zcopy)
+{
+	struct msghdr *msg = info->msg;
+
+	if (zcopy)
+		return __zerocopy_sg_from_iter(msg, NULL, skb,
+					       &msg->msg_iter, len, NULL);
+
+	virtio_vsock_skb_put(skb, len);
+	return skb_copy_datagram_from_iter_full(skb, 0, &msg->msg_iter, len);
+}
+
+static void virtio_transport_init_hdr(struct sk_buff *skb,
+				      struct virtio_vsock_pkt_info *info,
+				      size_t payload_len,
+				      u32 src_cid,
+				      u32 src_port,
+				      u32 dst_cid,
+				      u32 dst_port)
+{
+	struct virtio_vsock_hdr *hdr;
+
+	hdr = virtio_vsock_hdr(skb);
+	hdr->type	= cpu_to_le16(info->type);
+	hdr->op		= cpu_to_le16(info->op);
+	hdr->src_cid	= cpu_to_le64(src_cid);
+	hdr->dst_cid	= cpu_to_le64(dst_cid);
+	hdr->src_port	= cpu_to_le32(src_port);
+	hdr->dst_port	= cpu_to_le32(dst_port);
+	hdr->flags	= cpu_to_le32(info->flags);
+	hdr->len	= cpu_to_le32(payload_len);
+	hdr->buf_alloc	= cpu_to_le32(0);
+	hdr->fwd_cnt	= cpu_to_le32(0);
+}
+
+/* Packet capture */
+static struct sk_buff *virtio_transport_build_skb(void *opaque)
+{
+	struct virtio_vsock_hdr *pkt_hdr;
+	struct sk_buff *pkt = opaque;
+	struct af_vsockmon_hdr *hdr;
+	struct sk_buff *skb;
+	size_t payload_len;
+
+	/* A packet could be split to fit the RX buffer, so we use
+	 * the payload length from the header, which has been updated
+	 * by the sender to reflect the fragment size.
+	 */
+	pkt_hdr = virtio_vsock_hdr(pkt);
+	payload_len = le32_to_cpu(pkt_hdr->len);
+
+	skb = alloc_skb(sizeof(*hdr) + sizeof(*pkt_hdr) + payload_len,
+			GFP_ATOMIC);
+	if (!skb)
+		return NULL;
+
+	hdr = skb_put(skb, sizeof(*hdr));
+
+	/* pkt->hdr is little-endian so no need to byteswap here */
+	hdr->src_cid = pkt_hdr->src_cid;
+	hdr->src_port = pkt_hdr->src_port;
+	hdr->dst_cid = pkt_hdr->dst_cid;
+	hdr->dst_port = pkt_hdr->dst_port;
+
+	hdr->transport = cpu_to_le16(AF_VSOCK_TRANSPORT_VIRTIO);
+	hdr->len = cpu_to_le16(sizeof(*pkt_hdr));
+	memset(hdr->reserved, 0, sizeof(hdr->reserved));
+
+	switch (le16_to_cpu(pkt_hdr->op)) {
+	case VIRTIO_VSOCK_OP_REQUEST:
+	case VIRTIO_VSOCK_OP_RESPONSE:
+		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONNECT);
+		break;
+	case VIRTIO_VSOCK_OP_RST:
+	case VIRTIO_VSOCK_OP_SHUTDOWN:
+		hdr->op = cpu_to_le16(AF_VSOCK_OP_DISCONNECT);
+		break;
+	case VIRTIO_VSOCK_OP_RW:
+		hdr->op = cpu_to_le16(AF_VSOCK_OP_PAYLOAD);
+		break;
+	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
+	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
+		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
+		break;
+	default:
+		hdr->op = cpu_to_le16(AF_VSOCK_OP_UNKNOWN);
+		break;
+	}
+
+	skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr));
+
+	if (payload_len) {
+		struct iov_iter iov_iter;
+		struct kvec kvec;
+		void *data = skb_put(skb, payload_len);
+
+		kvec.iov_base = data;
+		kvec.iov_len = payload_len;
+		iov_iter_kvec(&iov_iter, ITER_DEST, &kvec, 1, payload_len);
+
+		if (skb_copy_datagram_iter(pkt, VIRTIO_VSOCK_SKB_CB(pkt)->offset,
+					   &iov_iter, payload_len)) {
+			kfree_skb(skb);
+			return NULL;
+		}
+	}
+
+	return skb;
+}
+
+void virtio_transport_deliver_tap_pkt(struct sk_buff *skb)
+{
+	if (virtio_vsock_skb_tap_delivered(skb))
+		return;
+
+	vsock_deliver_tap(virtio_transport_build_skb, skb);
+	virtio_vsock_skb_set_tap_delivered(skb);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
+
+static u16 virtio_transport_get_type(struct sock *sk)
+{
+	if (sk->sk_type == SOCK_STREAM)
+		return VIRTIO_VSOCK_TYPE_STREAM;
+	else
+		return VIRTIO_VSOCK_TYPE_SEQPACKET;
+}
+
+/* Returns new sk_buff on success, otherwise returns NULL. */
+static struct sk_buff *virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
+						  size_t payload_len,
+						  bool zcopy,
+						  struct ubuf_info *uarg,
+						  u32 src_cid,
+						  u32 src_port,
+						  u32 dst_cid,
+						  u32 dst_port)
+{
+	struct vsock_sock *vsk;
+	struct sk_buff *skb;
+	size_t skb_len;
+
+	skb_len = VIRTIO_VSOCK_SKB_HEADROOM;
+
+	if (!zcopy)
+		skb_len += payload_len;
+
+	skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	virtio_transport_init_hdr(skb, info, payload_len, src_cid, src_port,
+				  dst_cid, dst_port);
+
+	vsk = info->vsk;
+
+	/* If 'vsk' != NULL then payload is always present, so we
+	 * will never call '__zerocopy_sg_from_iter()' below without
+	 * setting skb owner in 'skb_set_owner_w()'. The only case
+	 * when 'vsk' == NULL is VIRTIO_VSOCK_OP_RST control message
+	 * without payload.
+	 */
+	WARN_ON_ONCE(!(vsk && (info->msg && payload_len)) && zcopy);
+
+	/* Set owner here, because '__zerocopy_sg_from_iter()' uses
+	 * owner of skb without check to update 'sk_wmem_alloc'.
+	 */
+	if (vsk)
+		skb_set_owner_w(skb, sk_vsock(vsk));
+
+	if (info->msg && payload_len > 0) {
+		int err;
+
+		/* Bind the zerocopy lifetime before filling frags so error
+		 * rollback frees managed fixed-buffer pages through
+		 * the uarg-aware path.
+		 */
+		skb_zcopy_set(skb, uarg, NULL);
+
+		err = virtio_transport_fill_skb(skb, info, payload_len, zcopy);
+		if (err)
+			goto out;
+
+		if (msg_data_left(info->msg) == 0 &&
+		    info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
+			struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+
+			hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
+
+			if (info->msg->msg_flags & MSG_EOR)
+				hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
+		}
+	}
+
+	if (info->reply)
+		virtio_vsock_skb_set_reply(skb);
+
+	trace_virtio_transport_alloc_pkt(src_cid, src_port,
+					 dst_cid, dst_port,
+					 payload_len,
+					 info->type,
+					 info->op,
+					 info->flags,
+					 zcopy);
+
+	return skb;
+out:
+	kfree_skb(skb);
+	return NULL;
+}
+
+/* This function can only be used on connecting/connected sockets,
+ * since a socket assigned to a transport is required.
+ *
+ * Do not use on listener sockets!
+ */
+static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
+					  struct virtio_vsock_pkt_info *info)
+{
+	u32 max_skb_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
+	u32 src_cid, src_port, dst_cid, dst_port;
+	const struct virtio_transport *t_ops;
+	struct iov_iter_state msg_iter_state;
+	struct virtio_vsock_sock *vvs;
+	struct ubuf_info *uarg = NULL;
+	u32 pkt_len = info->pkt_len;
+	bool can_zcopy = false;
+	bool have_uref = false;
+	u32 rest_len;
+	int ret;
+
+	info->type = virtio_transport_get_type(sk_vsock(vsk));
+
+	t_ops = virtio_transport_get_ops(vsk);
+	if (unlikely(!t_ops))
+		return -EFAULT;
+
+	src_cid = t_ops->transport.get_local_cid();
+	src_port = vsk->local_addr.svm_port;
+	if (!info->remote_cid) {
+		dst_cid	= vsk->remote_addr.svm_cid;
+		dst_port = vsk->remote_addr.svm_port;
+	} else {
+		dst_cid = info->remote_cid;
+		dst_port = info->remote_port;
+	}
+
+	vvs = vsk->trans;
+
+	/* virtio_transport_get_credit might return less than pkt_len credit */
+	pkt_len = virtio_transport_get_credit(vvs, pkt_len);
+
+	/* Do not send zero length OP_RW pkt */
+	if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
+		return pkt_len;
+
+	if (info->msg && (info->msg->msg_flags & MSG_ZEROCOPY)) {
+		/* If 'info->msg' is not NULL, this is only VIRTIO_VSOCK_OP_RW.
+		 * 'MSG_ZEROCOPY' flag handling here is based on the same flag
+		 * handling from 'tcp_sendmsg_locked()'.
+		 */
+		if (info->msg->msg_ubuf) {
+			uarg = info->msg->msg_ubuf;
+			can_zcopy = virtio_transport_can_zcopy(t_ops, info, pkt_len);
+		} else if (sock_flag(sk_vsock(vsk), SOCK_ZEROCOPY)) {
+			uarg = msg_zerocopy_realloc(sk_vsock(vsk), pkt_len,
+						    NULL, false);
+			if (!uarg) {
+				virtio_transport_put_credit(vvs, pkt_len);
+				return -ENOMEM;
+			}
+
+			can_zcopy = virtio_transport_can_zcopy(t_ops, info, pkt_len);
+			if (!can_zcopy)
+				uarg_to_msgzc(uarg)->zerocopy = 0;
+
+			have_uref = true;
+		}
+
+		/* 'can_zcopy' means that this transmission will be
+		 * in zerocopy way (e.g. using 'frags' array).
+		 */
+		if (can_zcopy)
+			max_skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE,
+					    (MAX_SKB_FRAGS * PAGE_SIZE));
+	}
+
+	rest_len = pkt_len;
+
+	do {
+		struct sk_buff *skb;
+		size_t skb_len;
+
+		/* Save iterator state in case allocation or transmission fails
+		 * so we can restore it and retry.
+		 */
+		if (info->msg)
+			iov_iter_save_state(&info->msg->msg_iter, &msg_iter_state);
+
+		skb_len = min(max_skb_len, rest_len);
+
+		/* Note: virtio_transport_alloc_skb() can advance info->msg->msg_iter
+		 * even if it fails (e.g. partial GUP success).
+		 */
+		skb = virtio_transport_alloc_skb(info, skb_len, can_zcopy,
+						 uarg,
+						 src_cid, src_port,
+						 dst_cid, dst_port);
+		if (!skb) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		virtio_transport_inc_tx_pkt(vvs, skb);
+
+		ret = t_ops->send_pkt(skb, info->net);
+		if (ret < 0)
+			break;
+
+		/* Both virtio and vhost 'send_pkt()' returns 'skb_len',
+		 * but for reliability use 'ret' instead of 'skb_len'.
+		 * Also if partial send happens (e.g. 'ret' != 'skb_len')
+		 * somehow, we break this loop, but account such returned
+		 * value in 'virtio_transport_put_credit()'.
+		 */
+		rest_len -= ret;
+
+		if (WARN_ONCE(ret != skb_len,
+			      "'send_pkt()' returns %i, but %zu expected\n",
+			      ret, skb_len))
+			break;
+	} while (rest_len);
+
+	if (info->msg && ret < 0)
+		iov_iter_restore(&info->msg->msg_iter, &msg_iter_state);
+
+	virtio_transport_put_credit(vvs, rest_len);
+
+	/* msg_zerocopy_realloc() initializes the ubuf_info refcnt to 1.
+	 * skb_zcopy_set() increases it for each skb, so we can drop that
+	 * initial reference to keep it balanced.
+	 */
+	if (have_uref) {
+		if (rest_len == pkt_len)
+			/* No data sent, abort the notification. */
+			net_zcopy_put_abort(uarg, true);
+		else
+			net_zcopy_put(uarg);
+	}
+
+	/* Return number of bytes, if any data has been sent. */
+	if (rest_len != pkt_len)
+		ret = pkt_len - rest_len;
+
+	return ret;
+}
+
+static bool virtio_transport_can_collapse(struct sk_buff *skb)
+{
+	/* skbs that are partially consumed, mark a SEQPACKET message boundary,
+	 * or are already large enough should not be collapsed: they either
+	 * need special accounting, carry protocol state, or already have a
+	 * good data-to-overhead ratio.
+	 */
+	if (VIRTIO_VSOCK_SKB_CB(skb)->offset)
+		return false;
+	if (le32_to_cpu(virtio_vsock_hdr(skb)->flags) & VIRTIO_VSOCK_SEQ_EOM)
+		return false;
+	if (skb->len >= MAX_COLLAPSE_LEN)
+		return false;
+	return true;
+}
+
+/* Iterate through the packets in the queue starting from the current skb to
+ * count the number of bytes we can collapse.
+ */
+static unsigned int
+virtio_transport_collapse_size(struct sk_buff *skb, struct sk_buff_head *queue)
+{
+	unsigned int target = skb->len - VIRTIO_VSOCK_SKB_CB(skb)->offset;
+
+	while ((skb = skb_peek_next(skb, queue)) &&
+	       virtio_transport_can_collapse(skb)) {
+		unsigned int len = skb->len - VIRTIO_VSOCK_SKB_CB(skb)->offset;
+
+		if (len > MAX_COLLAPSE_LEN - target)
+			return target;
+
+		target += len;
+	}
+
+	return target;
+}
+
+/* Called under lock_sock to compact the receive queue by merging small skbs.
+ * @min_to_free: minimum number of skbs to eliminate from the queue. May free
+ *               more to fill each collapsed skb to capacity.
+ */
+static void
+virtio_transport_collapse_rx_queue(struct virtio_vsock_sock *vvs,
+				   u32 min_to_free)
+{
+	struct sk_buff *skb, *next_skb, *new_skb = NULL;
+	struct sk_buff_head new_queue;
+	u32 saved = 0;
+
+	__skb_queue_head_init(&new_queue);
+
+	skb_queue_walk_safe(&vvs->rx_queue, skb, next_skb) {
+		struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+		u32 src_off = VIRTIO_VSOCK_SKB_CB(skb)->offset;
+		u32 src_len = skb->len - src_off;
+		bool keep;
+
+		keep = !virtio_transport_can_collapse(skb);
+		if (keep) {
+			/* Finalize pending collapsed skb to preserve packet
+			 * ordering.
+			 */
+			if (new_skb) {
+				__skb_queue_tail(&new_queue, new_skb);
+				new_skb = NULL;
+				saved--;
+			}
+			goto next;
+		}
+
+		/* Finalize if this packet won't fit in the remaining tailroom,
+		 * so we can allocate a right-sized new_skb.
+		 */
+		if (new_skb && src_len > skb_tailroom(new_skb)) {
+			__skb_queue_tail(&new_queue, new_skb);
+			new_skb = NULL;
+			saved--;
+		}
+
+		if (!new_skb) {
+			unsigned int alloc_size;
+
+			/* Check after finalizing to opportunistically fill
+			 * each collapsed skb to capacity, merging more skbs
+			 * than strictly required.
+			 */
+			if (saved >= min_to_free)
+				break;
+
+			alloc_size = virtio_transport_collapse_size(skb, &vvs->rx_queue);
+
+			/* Only this skb's data is eligible, nothing to merge
+			 * with. Keep as-is.
+			 */
+			if (alloc_size <= src_len) {
+				keep = true;
+				goto next;
+			}
+
+			new_skb = virtio_vsock_alloc_linear_skb(alloc_size +
+					VIRTIO_VSOCK_SKB_HEADROOM, GFP_KERNEL);
+			if (!new_skb)
+				break;
+
+			memcpy(virtio_vsock_hdr(new_skb), hdr,
+			       sizeof(struct virtio_vsock_hdr));
+			virtio_vsock_hdr(new_skb)->len = 0;
+		}
+
+		/* Cannot fail since src_off/src_len are within bounds, but if
+		 * it does, discard new_skb to avoid queuing corrupted data.
+		 */
+		if (WARN_ON_ONCE(skb_copy_bits(skb, src_off,
+					       skb_put(new_skb, src_len),
+					       src_len))) {
+			kfree_skb(new_skb);
+			new_skb = NULL;
+			break;
+		}
+
+		le32_add_cpu(&virtio_vsock_hdr(new_skb)->len, src_len);
+		virtio_vsock_hdr(new_skb)->flags |= hdr->flags;
+
+next:
+		__skb_unlink(skb, &vvs->rx_queue);
+		if (keep) {
+			__skb_queue_tail(&new_queue, skb);
+		} else {
+			consume_skb(skb);
+			saved++;
+		}
+	}
+
+	if (new_skb)
+		__skb_queue_tail(&new_queue, new_skb);
+
+	skb_queue_splice(&new_queue, &vvs->rx_queue);
+}
+
+static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
+					u32 len)
+{
+	u64 skb_overhead = (skb_queue_len(&vvs->rx_queue) + 1) * SKB_TRUESIZE(0);
+
+	/* Allow at most buf_alloc * 2 total budget (payload + overhead),
+	 * similar to how SO_RCVBUF is doubled to reserve space for sk_buff
+	 * metadata. Check payload against buf_alloc to be sure the other
+	 * peer is respecting the credit, and sk_buff overhead to bound
+	 * queue growth.
+	 */
+	if ((u64)vvs->buf_used + len > vvs->buf_alloc ||
+	    skb_overhead > vvs->buf_alloc)
+		return false;
+
+	vvs->rx_bytes += len;
+	vvs->buf_used += len;
+	return true;
+}
+
+static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
+					u32 bytes_read, u32 bytes_dequeued)
+{
+	vvs->rx_bytes -= bytes_read;
+	vvs->buf_used -= bytes_dequeued;
+	vvs->fwd_cnt += bytes_dequeued;
+}
+
+void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+
+	spin_lock_bh(&vvs->rx_lock);
+	vvs->last_fwd_cnt = vvs->fwd_cnt;
+	hdr->fwd_cnt = cpu_to_le32(vvs->fwd_cnt);
+	hdr->buf_alloc = cpu_to_le32(vvs->buf_alloc);
+	spin_unlock_bh(&vvs->rx_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt);
+
+void virtio_transport_consume_skb_sent(struct sk_buff *skb, bool consume)
+{
+	struct sock *s = skb->sk;
+
+	if (s && skb->len) {
+		struct vsock_sock *vs = vsock_sk(s);
+		struct virtio_vsock_sock *vvs;
+
+		vvs = vs->trans;
+
+		spin_lock_bh(&vvs->tx_lock);
+		vvs->bytes_unsent -= skb->len;
+		spin_unlock_bh(&vvs->tx_lock);
+	}
+
+	if (consume)
+		consume_skb(skb);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_consume_skb_sent);
+
+u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 credit)
+{
+	u32 ret;
+
+	if (!credit)
+		return 0;
+
+	spin_lock_bh(&vvs->tx_lock);
+	ret = min_t(u32, credit, virtio_transport_has_space(vvs));
+	vvs->tx_cnt += ret;
+	vvs->bytes_unsent += ret;
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_get_credit);
+
+void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit)
+{
+	if (!credit)
+		return;
+
+	spin_lock_bh(&vvs->tx_lock);
+	vvs->tx_cnt -= credit;
+	vvs->bytes_unsent -= credit;
+	spin_unlock_bh(&vvs->tx_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_put_credit);
+
+static int virtio_transport_send_credit_update(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_CREDIT_UPDATE,
+		.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
+static ssize_t
+virtio_transport_stream_do_peek(struct vsock_sock *vsk,
+				struct msghdr *msg,
+				size_t len)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	struct sk_buff *skb;
+	size_t total = 0;
+	int err;
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	skb_queue_walk(&vvs->rx_queue, skb) {
+		size_t bytes;
+
+		bytes = min_t(size_t, len - total,
+			      skb->len - VIRTIO_VSOCK_SKB_CB(skb)->offset);
+
+		spin_unlock_bh(&vvs->rx_lock);
+
+		/* sk_lock is held by caller so no one else can dequeue.
+		 * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
+		 */
+		err = skb_copy_datagram_iter(skb, VIRTIO_VSOCK_SKB_CB(skb)->offset,
+					     &msg->msg_iter, bytes);
+		if (err)
+			goto out;
+
+		total += bytes;
+
+		spin_lock_bh(&vvs->rx_lock);
+
+		if (total == len)
+			break;
+	}
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return total;
+
+out:
+	if (total)
+		err = total;
+	return err;
+}
+
+static ssize_t
+virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   size_t len)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	struct sk_buff *skb;
+	u32 fwd_cnt_delta;
+	bool low_rx_bytes;
+	int err = -EFAULT;
+	size_t total = 0;
+	u32 free_space;
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	if (WARN_ONCE(skb_queue_empty(&vvs->rx_queue) && vvs->rx_bytes,
+		      "rx_queue is empty, but rx_bytes is non-zero\n")) {
+		spin_unlock_bh(&vvs->rx_lock);
+		return err;
+	}
+
+	while (total < len && !skb_queue_empty(&vvs->rx_queue)) {
+		size_t bytes, dequeued = 0;
+
+		skb = skb_peek(&vvs->rx_queue);
+
+		bytes = min_t(size_t, len - total,
+			      skb->len - VIRTIO_VSOCK_SKB_CB(skb)->offset);
+
+		/* sk_lock is held by caller so no one else can dequeue.
+		 * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
+		 */
+		spin_unlock_bh(&vvs->rx_lock);
+
+		err = skb_copy_datagram_iter(skb,
+					     VIRTIO_VSOCK_SKB_CB(skb)->offset,
+					     &msg->msg_iter, bytes);
+		if (err)
+			goto out;
+
+		spin_lock_bh(&vvs->rx_lock);
+
+		total += bytes;
+
+		VIRTIO_VSOCK_SKB_CB(skb)->offset += bytes;
+
+		if (skb->len == VIRTIO_VSOCK_SKB_CB(skb)->offset) {
+			dequeued = le32_to_cpu(virtio_vsock_hdr(skb)->len);
+			__skb_unlink(skb, &vvs->rx_queue);
+			consume_skb(skb);
+		}
+
+		virtio_transport_dec_rx_pkt(vvs, bytes, dequeued);
+	}
+
+	fwd_cnt_delta = vvs->fwd_cnt - vvs->last_fwd_cnt;
+	free_space = vvs->buf_alloc - fwd_cnt_delta;
+	low_rx_bytes = (vvs->rx_bytes <
+			sock_rcvlowat(sk_vsock(vsk), 0, INT_MAX));
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	/* To reduce the number of credit update messages,
+	 * don't update credits as long as lots of space is available.
+	 * Note: the limit chosen here is arbitrary. Setting the limit
+	 * too high causes extra messages. Too low causes transmitter
+	 * stalls. As stalls are in theory more expensive than extra
+	 * messages, we set the limit to a high value. TODO: experiment
+	 * with different values. Also send credit update message when
+	 * number of bytes in rx queue is not enough to wake up reader.
+	 */
+	if (fwd_cnt_delta &&
+	    (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE || low_rx_bytes))
+		virtio_transport_send_credit_update(vsk);
+
+	return total;
+
+out:
+	if (total)
+		err = total;
+	return err;
+}
+
+static ssize_t
+virtio_transport_seqpacket_do_peek(struct vsock_sock *vsk,
+				   struct msghdr *msg)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	struct sk_buff *skb;
+	size_t total, len;
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	if (!vvs->msg_count) {
+		spin_unlock_bh(&vvs->rx_lock);
+		return 0;
+	}
+
+	total = 0;
+	len = msg_data_left(msg);
+
+	skb_queue_walk(&vvs->rx_queue, skb) {
+		struct virtio_vsock_hdr *hdr;
+
+		if (total < len) {
+			size_t bytes;
+			int err;
+
+			bytes = len - total;
+			if (bytes > skb->len)
+				bytes = skb->len;
+
+			spin_unlock_bh(&vvs->rx_lock);
+
+			/* sk_lock is held by caller so no one else can dequeue.
+			 * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
+			 */
+			err = skb_copy_datagram_iter(skb, VIRTIO_VSOCK_SKB_CB(skb)->offset,
+						     &msg->msg_iter, bytes);
+			if (err)
+				return err;
+
+			spin_lock_bh(&vvs->rx_lock);
+		}
+
+		total += skb->len;
+		hdr = virtio_vsock_hdr(skb);
+
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
+			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR)
+				msg->msg_flags |= MSG_EOR;
+
+			break;
+		}
+	}
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return total;
+}
+
+static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
+						 struct msghdr *msg,
+						 int flags)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	int dequeued_len = 0;
+	size_t user_buf_len = msg_data_left(msg);
+	bool msg_ready = false;
+	struct sk_buff *skb;
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	if (vvs->msg_count == 0) {
+		spin_unlock_bh(&vvs->rx_lock);
+		return 0;
+	}
+
+	while (!msg_ready) {
+		struct virtio_vsock_hdr *hdr;
+		size_t pkt_len;
+
+		skb = __skb_dequeue(&vvs->rx_queue);
+		if (!skb)
+			break;
+		hdr = virtio_vsock_hdr(skb);
+		pkt_len = (size_t)le32_to_cpu(hdr->len);
+
+		if (dequeued_len >= 0) {
+			size_t bytes_to_copy;
+
+			bytes_to_copy = min(user_buf_len, pkt_len);
+
+			if (bytes_to_copy) {
+				int err;
+
+				/* sk_lock is held by caller so no one else can dequeue.
+				 * Unlock rx_lock since skb_copy_datagram_iter() may sleep.
+				 */
+				spin_unlock_bh(&vvs->rx_lock);
+
+				err = skb_copy_datagram_iter(skb, 0,
+							     &msg->msg_iter,
+							     bytes_to_copy);
+				if (err) {
+					/* Copy of message failed. Rest of
+					 * fragments will be freed without copy.
+					 */
+					dequeued_len = err;
+				} else {
+					user_buf_len -= bytes_to_copy;
+				}
+
+				spin_lock_bh(&vvs->rx_lock);
+			}
+
+			if (dequeued_len >= 0)
+				dequeued_len += pkt_len;
+		}
+
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
+			msg_ready = true;
+			vvs->msg_count--;
+
+			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR)
+				msg->msg_flags |= MSG_EOR;
+		}
+
+		virtio_transport_dec_rx_pkt(vvs, pkt_len, pkt_len);
+		kfree_skb(skb);
+	}
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	virtio_transport_send_credit_update(vsk);
+
+	return dequeued_len;
+}
+
+ssize_t
+virtio_transport_stream_dequeue(struct vsock_sock *vsk,
+				struct msghdr *msg,
+				size_t len, int flags)
+{
+	if (flags & MSG_PEEK)
+		return virtio_transport_stream_do_peek(vsk, msg, len);
+	else
+		return virtio_transport_stream_do_dequeue(vsk, msg, len);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_dequeue);
+
+ssize_t
+virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   int flags)
+{
+	if (flags & MSG_PEEK)
+		return virtio_transport_seqpacket_do_peek(vsk, msg);
+	else
+		return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
+
+static u32 virtio_transport_tx_buf_size(struct virtio_vsock_sock *vvs)
+{
+	/* The peer advertises its receive buffer via peer_buf_alloc, but we
+	 * cap it to our local buf_alloc so a remote peer cannot force us to
+	 * queue more data than our own buffer configuration allows.
+	 */
+	return min(vvs->peer_buf_alloc, vvs->buf_alloc);
+}
+
+int
+virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   size_t len)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	spin_lock_bh(&vvs->tx_lock);
+
+	if (len > virtio_transport_tx_buf_size(vvs)) {
+		spin_unlock_bh(&vvs->tx_lock);
+		return -EMSGSIZE;
+	}
+
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return virtio_transport_stream_enqueue(vsk, msg, len);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
+
+int
+virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
+			       struct msghdr *msg,
+			       size_t len, int flags)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
+
+s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	s64 bytes;
+
+	spin_lock_bh(&vvs->rx_lock);
+	bytes = vvs->rx_bytes;
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_has_data);
+
+u32 virtio_transport_seqpacket_has_data(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	u32 msg_count;
+
+	spin_lock_bh(&vvs->rx_lock);
+	msg_count = vvs->msg_count;
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return msg_count;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_has_data);
+
+static s64 virtio_transport_has_space(struct virtio_vsock_sock *vvs)
+{
+	s64 bytes;
+
+	/* Use s64 arithmetic so if the peer shrinks peer_buf_alloc while
+	 * we have bytes in flight (tx_cnt - peer_fwd_cnt), the subtraction
+	 * does not underflow.
+	 */
+	bytes = (s64)virtio_transport_tx_buf_size(vvs) -
+		(vvs->tx_cnt - vvs->peer_fwd_cnt);
+	if (bytes < 0)
+		bytes = 0;
+
+	return bytes;
+}
+
+s64 virtio_transport_stream_has_space(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	s64 bytes;
+
+	spin_lock_bh(&vvs->tx_lock);
+	bytes = virtio_transport_has_space(vvs);
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_has_space);
+
+int virtio_transport_do_socket_init(struct vsock_sock *vsk,
+				    struct vsock_sock *psk)
+{
+	struct virtio_vsock_sock *vvs;
+
+	vvs = kzalloc_obj(*vvs);
+	if (!vvs)
+		return -ENOMEM;
+
+	vsk->trans = vvs;
+	vvs->vsk = vsk;
+	if (psk && psk->trans) {
+		struct virtio_vsock_sock *ptrans = psk->trans;
+
+		vvs->peer_buf_alloc = ptrans->peer_buf_alloc;
+	}
+
+	if (vsk->buffer_size > VIRTIO_VSOCK_MAX_BUF_SIZE)
+		vsk->buffer_size = VIRTIO_VSOCK_MAX_BUF_SIZE;
+
+	vvs->buf_alloc = vsk->buffer_size;
+
+	spin_lock_init(&vvs->rx_lock);
+	spin_lock_init(&vvs->tx_lock);
+	skb_queue_head_init(&vvs->rx_queue);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_do_socket_init);
+
+/* sk_lock held by the caller */
+void virtio_transport_notify_buffer_size(struct vsock_sock *vsk, u64 *val)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	if (*val > VIRTIO_VSOCK_MAX_BUF_SIZE)
+		*val = VIRTIO_VSOCK_MAX_BUF_SIZE;
+
+	vvs->buf_alloc = *val;
+
+	virtio_transport_send_credit_update(vsk);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_buffer_size);
+
+int
+virtio_transport_notify_poll_in(struct vsock_sock *vsk,
+				size_t target,
+				bool *data_ready_now)
+{
+	*data_ready_now = vsock_stream_has_data(vsk) >= target;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_poll_in);
+
+int
+virtio_transport_notify_poll_out(struct vsock_sock *vsk,
+				 size_t target,
+				 bool *space_avail_now)
+{
+	s64 free_space;
+
+	free_space = vsock_stream_has_space(vsk);
+	if (free_space > 0)
+		*space_avail_now = true;
+	else if (free_space == 0)
+		*space_avail_now = false;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_poll_out);
+
+int virtio_transport_notify_recv_init(struct vsock_sock *vsk,
+	size_t target, struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_init);
+
+int virtio_transport_notify_recv_pre_block(struct vsock_sock *vsk,
+	size_t target, struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_pre_block);
+
+int virtio_transport_notify_recv_pre_dequeue(struct vsock_sock *vsk,
+	size_t target, struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_pre_dequeue);
+
+int virtio_transport_notify_recv_post_dequeue(struct vsock_sock *vsk,
+	size_t target, ssize_t copied, bool data_read,
+	struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_post_dequeue);
+
+int virtio_transport_notify_send_init(struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_init);
+
+int virtio_transport_notify_send_pre_block(struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_pre_block);
+
+int virtio_transport_notify_send_pre_enqueue(struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_pre_enqueue);
+
+int virtio_transport_notify_send_post_enqueue(struct vsock_sock *vsk,
+	ssize_t written, struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_post_enqueue);
+
+u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk)
+{
+	return vsk->buffer_size;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_rcvhiwat);
+
+bool virtio_transport_stream_is_active(struct vsock_sock *vsk)
+{
+	return true;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_is_active);
+
+int virtio_transport_dgram_bind(struct vsock_sock *vsk,
+				struct sockaddr_vm *addr)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind);
+
+bool virtio_transport_dgram_allow(struct vsock_sock *vsk, u32 cid, u32 port)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_allow);
+
+int virtio_transport_connect(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_REQUEST,
+		.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_connect);
+
+int virtio_transport_shutdown(struct vsock_sock *vsk, int mode)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_SHUTDOWN,
+		.flags = (mode & RCV_SHUTDOWN ?
+			  VIRTIO_VSOCK_SHUTDOWN_RCV : 0) |
+			 (mode & SEND_SHUTDOWN ?
+			  VIRTIO_VSOCK_SHUTDOWN_SEND : 0),
+		.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_shutdown);
+
+int
+virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
+			       struct sockaddr_vm *remote_addr,
+			       struct msghdr *msg,
+			       size_t dgram_len)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_enqueue);
+
+ssize_t
+virtio_transport_stream_enqueue(struct vsock_sock *vsk,
+				struct msghdr *msg,
+				size_t len)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RW,
+		.msg = msg,
+		.pkt_len = len,
+		.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_enqueue);
+
+void virtio_transport_destruct(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	virtio_transport_cancel_close_work(vsk, true);
+
+	kfree(vvs);
+	vsk->trans = NULL;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_destruct);
+
+ssize_t virtio_transport_unsent_bytes(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	size_t ret;
+
+	spin_lock_bh(&vvs->tx_lock);
+	ret = vvs->bytes_unsent;
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_unsent_bytes);
+
+static int virtio_transport_reset(struct vsock_sock *vsk,
+				  struct sk_buff *skb)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RST,
+		.reply = !!skb,
+		.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
+	};
+
+	/* Send RST only if the original pkt is not a RST pkt */
+	if (skb && le16_to_cpu(virtio_vsock_hdr(skb)->op) == VIRTIO_VSOCK_OP_RST)
+		return 0;
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
+/* Normally packets are associated with a socket.  There may be no socket if an
+ * attempt was made to connect to a socket that does not exist.
+ *
+ * net refers to the namespace of whoever sent the invalid message. For
+ * loopback, this is the namespace of the socket. For vhost, this is the
+ * namespace of the VM (i.e., vhost_vsock).
+ */
+static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
+					  struct sk_buff *skb, struct net *net)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RST,
+		.type = le16_to_cpu(hdr->type),
+		.reply = true,
+
+		/* Set sk owner to socket we are replying to (may be NULL for
+		 * non-loopback). This keeps a reference to the sock and
+		 * sock_net(sk) until the reply skb is freed.
+		 */
+		.vsk = vsock_sk(skb->sk),
+
+		/* net is not defined here because we pass it directly to
+		 * t->send_pkt(), instead of relying on
+		 * virtio_transport_send_pkt_info() to pass it. It is not needed
+		 * by virtio_transport_alloc_skb().
+		 */
+	};
+	struct sk_buff *reply;
+
+	/* Send RST only if the original pkt is not a RST pkt */
+	if (le16_to_cpu(hdr->op) == VIRTIO_VSOCK_OP_RST)
+		return 0;
+
+	if (!t)
+		return -ENOTCONN;
+
+	reply = virtio_transport_alloc_skb(&info, 0, false, NULL,
+					   le64_to_cpu(hdr->dst_cid),
+					   le32_to_cpu(hdr->dst_port),
+					   le64_to_cpu(hdr->src_cid),
+					   le32_to_cpu(hdr->src_port));
+	if (!reply)
+		return -ENOMEM;
+
+	return t->send_pkt(reply, net);
+}
+
+/* This function should be called with sk_lock held and SOCK_DONE set */
+static void virtio_transport_remove_sock(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	/* We don't need to take rx_lock, as the socket is closing and we are
+	 * removing it.
+	 */
+	__skb_queue_purge(&vvs->rx_queue);
+	vsock_remove_sock(vsk);
+}
+
+static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
+					       bool cancel_timeout)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	if (vsk->close_work_scheduled &&
+	    (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) {
+		vsk->close_work_scheduled = false;
+
+		virtio_transport_remove_sock(vsk);
+
+		/* Release refcnt obtained when we scheduled the timeout */
+		sock_put(sk);
+	}
+}
+
+static void virtio_transport_do_close(struct vsock_sock *vsk,
+				      bool cancel_timeout)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_set_flag(sk, SOCK_DONE);
+	WRITE_ONCE(vsk->peer_shutdown, SHUTDOWN_MASK);
+	if (vsock_stream_has_data(vsk) <= 0)
+		sk->sk_state = TCP_CLOSING;
+	sk->sk_state_change(sk);
+
+	virtio_transport_cancel_close_work(vsk, cancel_timeout);
+}
+
+static void virtio_transport_close_timeout(struct work_struct *work)
+{
+	struct vsock_sock *vsk =
+		container_of(work, struct vsock_sock, close_work.work);
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_hold(sk);
+	lock_sock(sk);
+
+	if (!sock_flag(sk, SOCK_DONE)) {
+		(void)virtio_transport_reset(vsk, NULL);
+
+		virtio_transport_do_close(vsk, false);
+	}
+
+	vsk->close_work_scheduled = false;
+
+	release_sock(sk);
+	sock_put(sk);
+}
+
+/* User context, vsk->sk is locked */
+static bool virtio_transport_close(struct vsock_sock *vsk)
+{
+	struct sock *sk = &vsk->sk;
+
+	if (!(sk->sk_state == TCP_ESTABLISHED ||
+	      sk->sk_state == TCP_CLOSING))
+		return true;
+
+	/* Already received SHUTDOWN from peer, reply with RST */
+	if ((vsk->peer_shutdown & SHUTDOWN_MASK) == SHUTDOWN_MASK) {
+		(void)virtio_transport_reset(vsk, NULL);
+		return true;
+	}
+
+	if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
+		(void)virtio_transport_shutdown(vsk, SHUTDOWN_MASK);
+
+	if (!(current->flags & PF_EXITING))
+		vsock_linger(sk);
+
+	if (sock_flag(sk, SOCK_DONE)) {
+		return true;
+	}
+
+	sock_hold(sk);
+	INIT_DELAYED_WORK(&vsk->close_work,
+			  virtio_transport_close_timeout);
+	vsk->close_work_scheduled = true;
+	schedule_delayed_work(&vsk->close_work, VSOCK_CLOSE_TIMEOUT);
+	return false;
+}
+
+void virtio_transport_release(struct vsock_sock *vsk)
+{
+	struct sock *sk = &vsk->sk;
+	bool remove_sock = true;
+
+	if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
+		remove_sock = virtio_transport_close(vsk);
+
+	if (remove_sock) {
+		sock_set_flag(sk, SOCK_DONE);
+		virtio_transport_remove_sock(vsk);
+	}
+}
+EXPORT_SYMBOL_GPL(virtio_transport_release);
+
+static int
+virtio_transport_recv_connecting(struct sock *sk,
+				 struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	int skerr;
+	int err;
+
+	switch (le16_to_cpu(hdr->op)) {
+	case VIRTIO_VSOCK_OP_RESPONSE:
+		sk->sk_state = TCP_ESTABLISHED;
+		sk->sk_socket->state = SS_CONNECTED;
+		vsock_insert_connected(vsk);
+		sk->sk_state_change(sk);
+		break;
+	case VIRTIO_VSOCK_OP_INVALID:
+		break;
+	case VIRTIO_VSOCK_OP_RST:
+		skerr = ECONNRESET;
+		err = 0;
+		goto destroy;
+	default:
+		skerr = EPROTO;
+		err = -EINVAL;
+		goto destroy;
+	}
+	return 0;
+
+destroy:
+	virtio_transport_reset(vsk, skb);
+	sk->sk_state = TCP_CLOSE;
+	sk->sk_err = skerr;
+	sk_error_report(sk);
+	return err;
+}
+
+static bool
+virtio_transport_recv_enqueue(struct vsock_sock *vsk,
+			      struct sk_buff *skb)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	bool can_enqueue, free_pkt = false;
+	u32 len, queue_max, queue_len;
+	struct virtio_vsock_hdr *hdr;
+
+	hdr = virtio_vsock_hdr(skb);
+	len = le32_to_cpu(hdr->len);
+
+	/* virtio_transport_inc_rx_pkt() rejects packets when the per-skb
+	 * overhead (skb_queue_len * SKB_TRUESIZE(0)) exceeds buf_alloc.
+	 * Proactively collapse the queue before that happens.
+	 * No rx_lock needed: lock_sock is held by caller, preventing
+	 * concurrent enqueue or dequeue.
+	 */
+	queue_max = vvs->buf_alloc / SKB_TRUESIZE(0);
+	queue_len = skb_queue_len(&vvs->rx_queue);
+	if (queue_len >= queue_max) {
+		/* Walking a large queue may take a significant amount of time
+		 * and cache misses, causing traffic burstiness. Limit the
+		 * collapse to freeing room for this packet and the next one.
+		 * It may free more to fill each collapsed skb to capacity.
+		 */
+		virtio_transport_collapse_rx_queue(vvs, queue_len + 2 - queue_max);
+	}
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	can_enqueue = virtio_transport_inc_rx_pkt(vvs, len);
+	if (!can_enqueue)
+		goto out;
+
+	if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)
+		vvs->msg_count++;
+
+	/* Try to copy small packets into the buffer of last packet queued,
+	 * to avoid wasting memory queueing the entire buffer with a small
+	 * payload. Skip non-linear (e.g. zerocopy) skbs; these carry payload
+	 * in skb_shinfo.
+	 */
+	if (len <= GOOD_COPY_LEN && !skb_queue_empty(&vvs->rx_queue) &&
+	    !skb_is_nonlinear(skb)) {
+		struct virtio_vsock_hdr *last_hdr;
+		struct sk_buff *last_skb;
+
+		last_skb = skb_peek_tail(&vvs->rx_queue);
+		last_hdr = virtio_vsock_hdr(last_skb);
+
+		/* If there is space in the last packet queued, we copy the
+		 * new packet in its buffer. We avoid this if the last packet
+		 * queued has VIRTIO_VSOCK_SEQ_EOM set, because this is
+		 * delimiter of SEQPACKET message, so 'pkt' is the first packet
+		 * of a new message.
+		 */
+		if (skb->len < skb_tailroom(last_skb) &&
+		    !(le32_to_cpu(last_hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)) {
+			memcpy(skb_put(last_skb, skb->len), skb->data, skb->len);
+			free_pkt = true;
+			last_hdr->flags |= hdr->flags;
+			le32_add_cpu(&last_hdr->len, len);
+			goto out;
+		}
+	}
+
+	__skb_queue_tail(&vvs->rx_queue, skb);
+
+out:
+	spin_unlock_bh(&vvs->rx_lock);
+	if (free_pkt)
+		kfree_skb(skb);
+
+	return can_enqueue;
+}
+
+static int
+virtio_transport_recv_connected(struct sock *sk,
+				struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	int err = 0;
+
+	switch (le16_to_cpu(hdr->op)) {
+	case VIRTIO_VSOCK_OP_RW:
+		if (!virtio_transport_recv_enqueue(vsk, skb)) {
+			/* There is no more space to queue the packet, so let's
+			 * close the connection; otherwise, we'll lose data.
+			 */
+			(void)virtio_transport_reset(vsk, skb);
+			virtio_transport_do_close(vsk, true);
+			sk->sk_err = ENOBUFS;
+			sk_error_report(sk);
+			vsock_remove_sock(vsk);
+			break;
+		}
+		vsock_data_ready(sk);
+		return err;
+	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
+		virtio_transport_send_credit_update(vsk);
+		break;
+	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
+		sk->sk_write_space(sk);
+		break;
+	case VIRTIO_VSOCK_OP_SHUTDOWN: {
+		u32 peer_shutdown = READ_ONCE(vsk->peer_shutdown);
+
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SHUTDOWN_RCV)
+			peer_shutdown |= RCV_SHUTDOWN;
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SHUTDOWN_SEND)
+			peer_shutdown |= SEND_SHUTDOWN;
+		WRITE_ONCE(vsk->peer_shutdown, peer_shutdown);
+		if (peer_shutdown == SHUTDOWN_MASK) {
+			if (vsock_stream_has_data(vsk) <= 0 && !sock_flag(sk, SOCK_DONE)) {
+				(void)virtio_transport_reset(vsk, NULL);
+				virtio_transport_do_close(vsk, true);
+			}
+			/* Remove this socket anyway because the remote peer sent
+			 * the shutdown. This way a new connection will succeed
+			 * if the remote peer uses the same source port,
+			 * even if the old socket is still unreleased, but now disconnected.
+			 */
+			vsock_remove_sock(vsk);
+		}
+		if (le32_to_cpu(virtio_vsock_hdr(skb)->flags))
+			sk->sk_state_change(sk);
+		break;
+	}
+	case VIRTIO_VSOCK_OP_RST:
+		virtio_transport_do_close(vsk, true);
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	kfree_skb(skb);
+	return err;
+}
+
+static void
+virtio_transport_recv_disconnecting(struct sock *sk,
+				    struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (le16_to_cpu(hdr->op) == VIRTIO_VSOCK_OP_RST)
+		virtio_transport_do_close(vsk, true);
+}
+
+static int
+virtio_transport_send_response(struct vsock_sock *vsk,
+			       struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RESPONSE,
+		.remote_cid = le64_to_cpu(hdr->src_cid),
+		.remote_port = le32_to_cpu(hdr->src_port),
+		.reply = true,
+		.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
+static bool virtio_transport_space_update(struct sock *sk,
+					  struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	bool space_available;
+
+	/* Listener sockets are not associated with any transport, so we are
+	 * not able to take the state to see if there is space available in the
+	 * remote peer, but since they are only used to receive requests, we
+	 * can assume that there is always space available in the other peer.
+	 */
+	if (!vvs)
+		return true;
+
+	/* buf_alloc and fwd_cnt is always included in the hdr */
+	spin_lock_bh(&vvs->tx_lock);
+	vvs->peer_buf_alloc = le32_to_cpu(hdr->buf_alloc);
+	vvs->peer_fwd_cnt = le32_to_cpu(hdr->fwd_cnt);
+	space_available = virtio_transport_has_space(vvs);
+	spin_unlock_bh(&vvs->tx_lock);
+	return space_available;
+}
+
+/* Handle server socket */
+static int
+virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
+			     struct virtio_transport *t)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	struct vsock_sock *vchild;
+	struct sock *child;
+	int ret;
+
+	if (le16_to_cpu(hdr->op) != VIRTIO_VSOCK_OP_REQUEST) {
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
+		return -EINVAL;
+	}
+
+	if (sk_acceptq_is_full(sk)) {
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
+		return -ENOMEM;
+	}
+
+	/* __vsock_release() might have already flushed accept_queue.
+	 * Subsequent enqueues would lead to a memory leak.
+	 */
+	if (sk->sk_shutdown == SHUTDOWN_MASK) {
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
+		return -ESHUTDOWN;
+	}
+
+	child = vsock_create_connected(sk);
+	if (!child) {
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
+		return -ENOMEM;
+	}
+
+	lock_sock_nested(child, SINGLE_DEPTH_NESTING);
+
+	child->sk_state = TCP_ESTABLISHED;
+
+	vchild = vsock_sk(child);
+	vsock_addr_init(&vchild->local_addr, le64_to_cpu(hdr->dst_cid),
+			le32_to_cpu(hdr->dst_port));
+	vsock_addr_init(&vchild->remote_addr, le64_to_cpu(hdr->src_cid),
+			le32_to_cpu(hdr->src_port));
+
+	ret = vsock_assign_transport(vchild, vsk);
+	/* Transport assigned (looking at remote_addr) must be the same
+	 * where we received the request.
+	 */
+	if (ret || vchild->transport != &t->transport) {
+		release_sock(child);
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
+		sock_put(child);
+		return ret;
+	}
+
+	if (virtio_transport_space_update(child, skb))
+		child->sk_write_space(child);
+
+	vsock_insert_connected(vchild);
+	vsock_enqueue_accept(sk, child);
+	virtio_transport_send_response(vchild, skb);
+
+	release_sock(child);
+
+	sk->sk_data_ready(sk);
+	return 0;
+}
+
+static bool virtio_transport_valid_type(u16 type)
+{
+	return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
+	       (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
+}
+
+/* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
+ * lock.
+ */
+void virtio_transport_recv_pkt(struct virtio_transport *t,
+			       struct sk_buff *skb, struct net *net)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct sockaddr_vm src, dst;
+	struct vsock_sock *vsk;
+	struct sock *sk;
+	bool space_available;
+
+	vsock_addr_init(&src, le64_to_cpu(hdr->src_cid),
+			le32_to_cpu(hdr->src_port));
+	vsock_addr_init(&dst, le64_to_cpu(hdr->dst_cid),
+			le32_to_cpu(hdr->dst_port));
+
+	trace_virtio_transport_recv_pkt(src.svm_cid, src.svm_port,
+					dst.svm_cid, dst.svm_port,
+					le32_to_cpu(hdr->len),
+					le16_to_cpu(hdr->type),
+					le16_to_cpu(hdr->op),
+					le32_to_cpu(hdr->flags),
+					le32_to_cpu(hdr->buf_alloc),
+					le32_to_cpu(hdr->fwd_cnt));
+
+	if (!virtio_transport_valid_type(le16_to_cpu(hdr->type))) {
+		(void)virtio_transport_reset_no_sock(t, skb, net);
+		goto free_pkt;
+	}
+
+	/* The socket must be in connected or bound table
+	 * otherwise send reset back
+	 */
+	sk = vsock_find_connected_socket_net(&src, &dst, net);
+	if (!sk) {
+		sk = vsock_find_bound_socket_net(&dst, net);
+		if (!sk) {
+			(void)virtio_transport_reset_no_sock(t, skb, net);
+			goto free_pkt;
+		}
+	}
+
+	if (virtio_transport_get_type(sk) != le16_to_cpu(hdr->type)) {
+		(void)virtio_transport_reset_no_sock(t, skb, net);
+		sock_put(sk);
+		goto free_pkt;
+	}
+
+	if (!skb_set_owner_sk_safe(skb, sk)) {
+		WARN_ONCE(1, "receiving vsock socket has sk_refcnt == 0\n");
+		goto free_pkt;
+	}
+
+	vsk = vsock_sk(sk);
+
+	lock_sock(sk);
+
+	/* Check if sk has been closed or assigned to another transport before
+	 * lock_sock (note: listener sockets are not assigned to any transport)
+	 */
+	if (sock_flag(sk, SOCK_DONE) ||
+	    (sk->sk_state != TCP_LISTEN && vsk->transport != &t->transport)) {
+		(void)virtio_transport_reset_no_sock(t, skb, net);
+		release_sock(sk);
+		sock_put(sk);
+		goto free_pkt;
+	}
+
+	space_available = virtio_transport_space_update(sk, skb);
+
+	/* Update CID in case it has changed after a transport reset event */
+	if (vsk->local_addr.svm_cid != VMADDR_CID_ANY)
+		vsk->local_addr.svm_cid = dst.svm_cid;
+
+	if (space_available)
+		sk->sk_write_space(sk);
+
+	switch (sk->sk_state) {
+	case TCP_LISTEN:
+		virtio_transport_recv_listen(sk, skb, t);
+		kfree_skb(skb);
+		break;
+	case TCP_SYN_SENT:
+		virtio_transport_recv_connecting(sk, skb);
+		kfree_skb(skb);
+		break;
+	case TCP_ESTABLISHED:
+		virtio_transport_recv_connected(sk, skb);
+		break;
+	case TCP_CLOSING:
+		virtio_transport_recv_disconnecting(sk, skb);
+		kfree_skb(skb);
+		break;
+	default:
+		(void)virtio_transport_reset_no_sock(t, skb, net);
+		kfree_skb(skb);
+		break;
+	}
+
+	release_sock(sk);
+
+	/* Release refcnt obtained when we fetched this socket out of the
+	 * bound or connected list.
+	 */
+	sock_put(sk);
+	return;
+
+free_pkt:
+	kfree_skb(skb);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_recv_pkt);
+
+/* Remove skbs found in a queue that have a vsk that matches.
+ *
+ * Each skb is freed.
+ *
+ * Returns the count of skbs that were reply packets.
+ */
+int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *queue)
+{
+	struct sk_buff_head freeme;
+	struct sk_buff *skb, *tmp;
+	int cnt = 0;
+
+	skb_queue_head_init(&freeme);
+
+	spin_lock_bh(&queue->lock);
+	skb_queue_walk_safe(queue, skb, tmp) {
+		if (vsock_sk(skb->sk) != vsk)
+			continue;
+
+		__skb_unlink(skb, queue);
+		__skb_queue_tail(&freeme, skb);
+
+		if (virtio_vsock_skb_reply(skb))
+			cnt++;
+	}
+	spin_unlock_bh(&queue->lock);
+
+	__skb_queue_purge(&freeme);
+
+	return cnt;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_purge_skbs);
+
+int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_actor)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	struct sock *sk = sk_vsock(vsk);
+	struct virtio_vsock_hdr *hdr;
+	struct sk_buff *skb;
+	u32 pkt_len;
+	int off = 0;
+	int err;
+
+	spin_lock_bh(&vvs->rx_lock);
+	/* Use __skb_recv_datagram() for race-free handling of the receive. It
+	 * works for types other than dgrams.
+	 */
+	skb = __skb_recv_datagram(sk, &vvs->rx_queue, MSG_DONTWAIT, &off, &err);
+	if (!skb) {
+		spin_unlock_bh(&vvs->rx_lock);
+		return err;
+	}
+
+	hdr = virtio_vsock_hdr(skb);
+	if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)
+		vvs->msg_count--;
+
+	pkt_len = le32_to_cpu(hdr->len);
+	virtio_transport_dec_rx_pkt(vvs, pkt_len, pkt_len);
+	spin_unlock_bh(&vvs->rx_lock);
+
+	virtio_transport_send_credit_update(vsk);
+
+	return recv_actor(sk, skb);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_read_skb);
+
+int virtio_transport_notify_set_rcvlowat(struct vsock_sock *vsk, int val)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	bool send_update;
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	/* If number of available bytes is less than new SO_RCVLOWAT value,
+	 * kick sender to send more data, because sender may sleep in its
+	 * 'send()' syscall waiting for enough space at our side. Also
+	 * don't send credit update when peer already knows actual value -
+	 * such transmission will be useless.
+	 */
+	send_update = (vvs->rx_bytes < val) &&
+		      (vvs->fwd_cnt != vvs->last_fwd_cnt);
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	if (send_update) {
+		int err;
+
+		err = virtio_transport_send_credit_update(vsk);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_set_rcvlowat);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Asias He");
+MODULE_DESCRIPTION("common code for virtio vsock");
diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
new file mode 100644
index 000000000..1c4ee039c
--- /dev/null
+++ b/net/vmw_vsock/vmci_transport.c
@@ -0,0 +1,2172 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2007-2013 VMware, Inc. All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/cred.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/net.h>
+#include <linux/poll.h>
+#include <linux/skbuff.h>
+#include <linux/smp.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <linux/unistd.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <net/sock.h>
+#include <net/af_vsock.h>
+
+#include "vmci_transport_notify.h"
+
+static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg);
+static int vmci_transport_recv_stream_cb(void *data, struct vmci_datagram *dg);
+static void vmci_transport_peer_detach_cb(u32 sub_id,
+					  const struct vmci_event_data *ed,
+					  void *client_data);
+static void vmci_transport_recv_pkt_work(struct work_struct *work);
+static void vmci_transport_cleanup(struct work_struct *work);
+static int vmci_transport_recv_listen(struct sock *sk,
+				      struct vmci_transport_packet *pkt);
+static int vmci_transport_recv_connecting_server(
+					struct sock *sk,
+					struct sock *pending,
+					struct vmci_transport_packet *pkt);
+static int vmci_transport_recv_connecting_client(
+					struct sock *sk,
+					struct vmci_transport_packet *pkt);
+static int vmci_transport_recv_connecting_client_negotiate(
+					struct sock *sk,
+					struct vmci_transport_packet *pkt);
+static int vmci_transport_recv_connecting_client_invalid(
+					struct sock *sk,
+					struct vmci_transport_packet *pkt);
+static int vmci_transport_recv_connected(struct sock *sk,
+					 struct vmci_transport_packet *pkt);
+static bool vmci_transport_old_proto_override(bool *old_pkt_proto);
+static u16 vmci_transport_new_proto_supported_versions(void);
+static bool vmci_transport_proto_to_notify_struct(struct sock *sk, u16 *proto,
+						  bool old_pkt_proto);
+static bool vmci_check_transport(struct vsock_sock *vsk);
+
+struct vmci_transport_recv_pkt_info {
+	struct work_struct work;
+	struct sock *sk;
+	struct vmci_transport_packet pkt;
+};
+
+static LIST_HEAD(vmci_transport_cleanup_list);
+static DEFINE_SPINLOCK(vmci_transport_cleanup_lock);
+static DECLARE_WORK(vmci_transport_cleanup_work, vmci_transport_cleanup);
+
+static struct vmci_handle vmci_transport_stream_handle = { VMCI_INVALID_ID,
+							   VMCI_INVALID_ID };
+static u32 vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;
+
+static int PROTOCOL_OVERRIDE = -1;
+
+static struct vsock_transport vmci_transport; /* forward declaration */
+
+/* Helper function to convert from a VMCI error code to a VSock error code. */
+
+static s32 vmci_transport_error_to_vsock_error(s32 vmci_error)
+{
+	switch (vmci_error) {
+	case VMCI_ERROR_NO_MEM:
+		return -ENOMEM;
+	case VMCI_ERROR_DUPLICATE_ENTRY:
+	case VMCI_ERROR_ALREADY_EXISTS:
+		return -EADDRINUSE;
+	case VMCI_ERROR_NO_ACCESS:
+		return -EPERM;
+	case VMCI_ERROR_NO_RESOURCES:
+		return -ENOBUFS;
+	case VMCI_ERROR_INVALID_RESOURCE:
+		return -EHOSTUNREACH;
+	case VMCI_ERROR_INVALID_ARGS:
+	default:
+		break;
+	}
+	return -EINVAL;
+}
+
+static u32 vmci_transport_peer_rid(u32 peer_cid)
+{
+	if (VMADDR_CID_HYPERVISOR == peer_cid)
+		return VMCI_TRANSPORT_HYPERVISOR_PACKET_RID;
+
+	return VMCI_TRANSPORT_PACKET_RID;
+}
+
+static inline void
+vmci_transport_packet_init(struct vmci_transport_packet *pkt,
+			   struct sockaddr_vm *src,
+			   struct sockaddr_vm *dst,
+			   u8 type,
+			   u64 size,
+			   u64 mode,
+			   struct vmci_transport_waiting_info *wait,
+			   u16 proto,
+			   struct vmci_handle handle)
+{
+	memset(pkt, 0, sizeof(*pkt));
+
+	/* We register the stream control handler as an any cid handle so we
+	 * must always send from a source address of VMADDR_CID_ANY
+	 */
+	pkt->dg.src = vmci_make_handle(VMADDR_CID_ANY,
+				       VMCI_TRANSPORT_PACKET_RID);
+	pkt->dg.dst = vmci_make_handle(dst->svm_cid,
+				       vmci_transport_peer_rid(dst->svm_cid));
+	pkt->dg.payload_size = sizeof(*pkt) - sizeof(pkt->dg);
+	pkt->version = VMCI_TRANSPORT_PACKET_VERSION;
+	pkt->type = type;
+	pkt->src_port = src->svm_port;
+	pkt->dst_port = dst->svm_port;
+
+	switch (pkt->type) {
+	case VMCI_TRANSPORT_PACKET_TYPE_INVALID:
+		pkt->u.size = 0;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_REQUEST:
+	case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE:
+		pkt->u.size = size;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_OFFER:
+	case VMCI_TRANSPORT_PACKET_TYPE_ATTACH:
+		pkt->u.handle = handle;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
+	case VMCI_TRANSPORT_PACKET_TYPE_READ:
+	case VMCI_TRANSPORT_PACKET_TYPE_RST:
+		pkt->u.size = 0;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN:
+		pkt->u.mode = mode;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_WAITING_READ:
+	case VMCI_TRANSPORT_PACKET_TYPE_WAITING_WRITE:
+		pkt->u.wait = *wait;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_REQUEST2:
+	case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2:
+		pkt->u.size = size;
+		pkt->proto = proto;
+		break;
+	}
+}
+
+static inline void
+vmci_transport_packet_get_addresses(struct vmci_transport_packet *pkt,
+				    struct sockaddr_vm *local,
+				    struct sockaddr_vm *remote)
+{
+	vsock_addr_init(local, pkt->dg.dst.context, pkt->dst_port);
+	vsock_addr_init(remote, pkt->dg.src.context, pkt->src_port);
+}
+
+static int
+__vmci_transport_send_control_pkt(struct vmci_transport_packet *pkt,
+				  struct sockaddr_vm *src,
+				  struct sockaddr_vm *dst,
+				  enum vmci_transport_packet_type type,
+				  u64 size,
+				  u64 mode,
+				  struct vmci_transport_waiting_info *wait,
+				  u16 proto,
+				  struct vmci_handle handle,
+				  bool convert_error)
+{
+	int err;
+
+	vmci_transport_packet_init(pkt, src, dst, type, size, mode, wait,
+				   proto, handle);
+	err = vmci_datagram_send(&pkt->dg);
+	if (convert_error && (err < 0))
+		return vmci_transport_error_to_vsock_error(err);
+
+	return err;
+}
+
+static int
+vmci_transport_reply_control_pkt_fast(struct vmci_transport_packet *pkt,
+				      enum vmci_transport_packet_type type,
+				      u64 size,
+				      u64 mode,
+				      struct vmci_transport_waiting_info *wait,
+				      struct vmci_handle handle)
+{
+	struct vmci_transport_packet reply;
+	struct sockaddr_vm src, dst;
+
+	if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST) {
+		return 0;
+	} else {
+		vmci_transport_packet_get_addresses(pkt, &src, &dst);
+		return __vmci_transport_send_control_pkt(&reply, &src, &dst,
+							 type,
+							 size, mode, wait,
+							 VSOCK_PROTO_INVALID,
+							 handle, true);
+	}
+}
+
+static int
+vmci_transport_send_control_pkt_bh(struct sockaddr_vm *src,
+				   struct sockaddr_vm *dst,
+				   enum vmci_transport_packet_type type,
+				   u64 size,
+				   u64 mode,
+				   struct vmci_transport_waiting_info *wait,
+				   struct vmci_handle handle)
+{
+	/* Note that it is safe to use a single packet across all CPUs since
+	 * two tasklets of the same type are guaranteed to not ever run
+	 * simultaneously. If that ever changes, or VMCI stops using tasklets,
+	 * we can use per-cpu packets.
+	 */
+	static struct vmci_transport_packet pkt;
+
+	return __vmci_transport_send_control_pkt(&pkt, src, dst, type,
+						 size, mode, wait,
+						 VSOCK_PROTO_INVALID, handle,
+						 false);
+}
+
+static int
+vmci_transport_alloc_send_control_pkt(struct sockaddr_vm *src,
+				      struct sockaddr_vm *dst,
+				      enum vmci_transport_packet_type type,
+				      u64 size,
+				      u64 mode,
+				      struct vmci_transport_waiting_info *wait,
+				      u16 proto,
+				      struct vmci_handle handle)
+{
+	struct vmci_transport_packet *pkt;
+	int err;
+
+	pkt = kmalloc_obj(*pkt);
+	if (!pkt)
+		return -ENOMEM;
+
+	err = __vmci_transport_send_control_pkt(pkt, src, dst, type, size,
+						mode, wait, proto, handle,
+						true);
+	kfree(pkt);
+
+	return err;
+}
+
+static int
+vmci_transport_send_control_pkt(struct sock *sk,
+				enum vmci_transport_packet_type type,
+				u64 size,
+				u64 mode,
+				struct vmci_transport_waiting_info *wait,
+				u16 proto,
+				struct vmci_handle handle)
+{
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+
+	if (!vsock_addr_bound(&vsk->local_addr))
+		return -EINVAL;
+
+	if (!vsock_addr_bound(&vsk->remote_addr))
+		return -EINVAL;
+
+	return vmci_transport_alloc_send_control_pkt(&vsk->local_addr,
+						     &vsk->remote_addr,
+						     type, size, mode,
+						     wait, proto, handle);
+}
+
+static int vmci_transport_send_reset_bh(struct sockaddr_vm *dst,
+					struct sockaddr_vm *src,
+					struct vmci_transport_packet *pkt)
+{
+	if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
+		return 0;
+	return vmci_transport_send_control_pkt_bh(
+					dst, src,
+					VMCI_TRANSPORT_PACKET_TYPE_RST, 0,
+					0, NULL, VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_reset(struct sock *sk,
+				     struct vmci_transport_packet *pkt)
+{
+	struct sockaddr_vm *dst_ptr;
+	struct sockaddr_vm dst;
+	struct vsock_sock *vsk;
+
+	if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
+		return 0;
+
+	vsk = vsock_sk(sk);
+
+	if (!vsock_addr_bound(&vsk->local_addr))
+		return -EINVAL;
+
+	if (vsock_addr_bound(&vsk->remote_addr)) {
+		dst_ptr = &vsk->remote_addr;
+	} else {
+		vsock_addr_init(&dst, pkt->dg.src.context,
+				pkt->src_port);
+		dst_ptr = &dst;
+	}
+	return vmci_transport_alloc_send_control_pkt(&vsk->local_addr, dst_ptr,
+					     VMCI_TRANSPORT_PACKET_TYPE_RST,
+					     0, 0, NULL, VSOCK_PROTO_INVALID,
+					     VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_negotiate(struct sock *sk, size_t size)
+{
+	return vmci_transport_send_control_pkt(
+					sk,
+					VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE,
+					size, 0, NULL,
+					VSOCK_PROTO_INVALID,
+					VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_negotiate2(struct sock *sk, size_t size,
+					  u16 version)
+{
+	return vmci_transport_send_control_pkt(
+					sk,
+					VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2,
+					size, 0, NULL, version,
+					VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_qp_offer(struct sock *sk,
+					struct vmci_handle handle)
+{
+	return vmci_transport_send_control_pkt(
+					sk, VMCI_TRANSPORT_PACKET_TYPE_OFFER, 0,
+					0, NULL,
+					VSOCK_PROTO_INVALID, handle);
+}
+
+static int vmci_transport_send_attach(struct sock *sk,
+				      struct vmci_handle handle)
+{
+	return vmci_transport_send_control_pkt(
+					sk, VMCI_TRANSPORT_PACKET_TYPE_ATTACH,
+					0, 0, NULL, VSOCK_PROTO_INVALID,
+					handle);
+}
+
+static int vmci_transport_reply_reset(struct vmci_transport_packet *pkt)
+{
+	return vmci_transport_reply_control_pkt_fast(
+						pkt,
+						VMCI_TRANSPORT_PACKET_TYPE_RST,
+						0, 0, NULL,
+						VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_invalid_bh(struct sockaddr_vm *dst,
+					  struct sockaddr_vm *src)
+{
+	return vmci_transport_send_control_pkt_bh(
+					dst, src,
+					VMCI_TRANSPORT_PACKET_TYPE_INVALID,
+					0, 0, NULL, VMCI_INVALID_HANDLE);
+}
+
+int vmci_transport_send_wrote_bh(struct sockaddr_vm *dst,
+				 struct sockaddr_vm *src)
+{
+	return vmci_transport_send_control_pkt_bh(
+					dst, src,
+					VMCI_TRANSPORT_PACKET_TYPE_WROTE, 0,
+					0, NULL, VMCI_INVALID_HANDLE);
+}
+
+int vmci_transport_send_read_bh(struct sockaddr_vm *dst,
+				struct sockaddr_vm *src)
+{
+	return vmci_transport_send_control_pkt_bh(
+					dst, src,
+					VMCI_TRANSPORT_PACKET_TYPE_READ, 0,
+					0, NULL, VMCI_INVALID_HANDLE);
+}
+
+int vmci_transport_send_wrote(struct sock *sk)
+{
+	return vmci_transport_send_control_pkt(
+					sk, VMCI_TRANSPORT_PACKET_TYPE_WROTE, 0,
+					0, NULL, VSOCK_PROTO_INVALID,
+					VMCI_INVALID_HANDLE);
+}
+
+int vmci_transport_send_read(struct sock *sk)
+{
+	return vmci_transport_send_control_pkt(
+					sk, VMCI_TRANSPORT_PACKET_TYPE_READ, 0,
+					0, NULL, VSOCK_PROTO_INVALID,
+					VMCI_INVALID_HANDLE);
+}
+
+int vmci_transport_send_waiting_write(struct sock *sk,
+				      struct vmci_transport_waiting_info *wait)
+{
+	return vmci_transport_send_control_pkt(
+				sk, VMCI_TRANSPORT_PACKET_TYPE_WAITING_WRITE,
+				0, 0, wait, VSOCK_PROTO_INVALID,
+				VMCI_INVALID_HANDLE);
+}
+
+int vmci_transport_send_waiting_read(struct sock *sk,
+				     struct vmci_transport_waiting_info *wait)
+{
+	return vmci_transport_send_control_pkt(
+				sk, VMCI_TRANSPORT_PACKET_TYPE_WAITING_READ,
+				0, 0, wait, VSOCK_PROTO_INVALID,
+				VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_shutdown(struct vsock_sock *vsk, int mode)
+{
+	return vmci_transport_send_control_pkt(
+					&vsk->sk,
+					VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN,
+					0, mode, NULL,
+					VSOCK_PROTO_INVALID,
+					VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_conn_request(struct sock *sk, size_t size)
+{
+	return vmci_transport_send_control_pkt(sk,
+					VMCI_TRANSPORT_PACKET_TYPE_REQUEST,
+					size, 0, NULL,
+					VSOCK_PROTO_INVALID,
+					VMCI_INVALID_HANDLE);
+}
+
+static int vmci_transport_send_conn_request2(struct sock *sk, size_t size,
+					     u16 version)
+{
+	return vmci_transport_send_control_pkt(
+					sk, VMCI_TRANSPORT_PACKET_TYPE_REQUEST2,
+					size, 0, NULL, version,
+					VMCI_INVALID_HANDLE);
+}
+
+static struct sock *vmci_transport_get_pending(
+					struct sock *listener,
+					struct vmci_transport_packet *pkt)
+{
+	struct vsock_sock *vlistener;
+	struct vsock_sock *vpending;
+	struct sock *pending;
+	struct sockaddr_vm src;
+
+	vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port);
+
+	vlistener = vsock_sk(listener);
+
+	list_for_each_entry(vpending, &vlistener->pending_links,
+			    pending_links) {
+		if (vsock_addr_equals_addr(&src, &vpending->remote_addr) &&
+		    pkt->dst_port == vpending->local_addr.svm_port) {
+			pending = sk_vsock(vpending);
+			sock_hold(pending);
+			goto found;
+		}
+	}
+
+	pending = NULL;
+found:
+	return pending;
+
+}
+
+static void vmci_transport_release_pending(struct sock *pending)
+{
+	sock_put(pending);
+}
+
+/* We allow two kinds of sockets to communicate with a restricted VM: 1)
+ * trusted sockets 2) sockets from applications running as the same user as the
+ * VM (this is only true for the host side and only when using hosted products)
+ */
+
+static bool vmci_transport_is_trusted(struct vsock_sock *vsock, u32 peer_cid)
+{
+	return vsock->trusted ||
+	       vmci_is_context_owner(peer_cid, vsock->owner->uid);
+}
+
+/* We allow sending datagrams to and receiving datagrams from a restricted VM
+ * only if it is trusted as described in vmci_transport_is_trusted.
+ */
+
+static bool vmci_transport_allow_dgram(struct vsock_sock *vsock, u32 peer_cid)
+{
+	if (VMADDR_CID_HYPERVISOR == peer_cid)
+		return true;
+
+	if (vsock->cached_peer != peer_cid) {
+		vsock->cached_peer = peer_cid;
+		if (!vmci_transport_is_trusted(vsock, peer_cid) &&
+		    (vmci_context_get_priv_flags(peer_cid) &
+		     VMCI_PRIVILEGE_FLAG_RESTRICTED)) {
+			vsock->cached_peer_allow_dgram = false;
+		} else {
+			vsock->cached_peer_allow_dgram = true;
+		}
+	}
+
+	return vsock->cached_peer_allow_dgram;
+}
+
+static int
+vmci_transport_queue_pair_alloc(struct vmci_qp **qpair,
+				struct vmci_handle *handle,
+				u64 produce_size,
+				u64 consume_size,
+				u32 peer, u32 flags, bool trusted)
+{
+	int err = 0;
+
+	if (trusted) {
+		/* Try to allocate our queue pair as trusted. This will only
+		 * work if vsock is running in the host.
+		 */
+
+		err = vmci_qpair_alloc(qpair, handle, produce_size,
+				       consume_size,
+				       peer, flags,
+				       VMCI_PRIVILEGE_FLAG_TRUSTED);
+		if (err != VMCI_ERROR_NO_ACCESS)
+			goto out;
+
+	}
+
+	err = vmci_qpair_alloc(qpair, handle, produce_size, consume_size,
+			       peer, flags, VMCI_NO_PRIVILEGE_FLAGS);
+out:
+	if (err < 0) {
+		pr_err_once("Could not attach to queue pair with %d\n", err);
+		err = vmci_transport_error_to_vsock_error(err);
+	}
+
+	return err;
+}
+
+static int
+vmci_transport_datagram_create_hnd(u32 resource_id,
+				   u32 flags,
+				   vmci_datagram_recv_cb recv_cb,
+				   void *client_data,
+				   struct vmci_handle *out_handle)
+{
+	int err = 0;
+
+	/* Try to allocate our datagram handler as trusted. This will only work
+	 * if vsock is running in the host.
+	 */
+
+	err = vmci_datagram_create_handle_priv(resource_id, flags,
+					       VMCI_PRIVILEGE_FLAG_TRUSTED,
+					       recv_cb,
+					       client_data, out_handle);
+
+	if (err == VMCI_ERROR_NO_ACCESS)
+		err = vmci_datagram_create_handle(resource_id, flags,
+						  recv_cb, client_data,
+						  out_handle);
+
+	return err;
+}
+
+/* This is invoked as part of a tasklet that's scheduled when the VMCI
+ * interrupt fires.  This is run in bottom-half context and if it ever needs to
+ * sleep it should defer that work to a work queue.
+ */
+
+static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
+{
+	struct sock *sk;
+	size_t size;
+	struct sk_buff *skb;
+	struct vsock_sock *vsk;
+
+	sk = (struct sock *)data;
+
+	/* This handler is privileged when this module is running on the host.
+	 * We will get datagrams from all endpoints (even VMs that are in a
+	 * restricted context). If we get one from a restricted context then
+	 * the destination socket must be trusted.
+	 *
+	 * NOTE: We access the socket struct without holding the lock here.
+	 * This is ok because the field we are interested is never modified
+	 * outside of the create and destruct socket functions.
+	 */
+	vsk = vsock_sk(sk);
+	if (!vmci_transport_allow_dgram(vsk, dg->src.context))
+		return VMCI_ERROR_NO_ACCESS;
+
+	size = VMCI_DG_SIZE(dg);
+
+	/* Attach the packet to the socket's receive queue as an sk_buff. */
+	skb = alloc_skb(size, GFP_ATOMIC);
+	if (!skb)
+		return VMCI_ERROR_NO_MEM;
+
+	/* sk_receive_skb() will do a sock_put(), so hold here. */
+	sock_hold(sk);
+	skb_put(skb, size);
+	memcpy(skb->data, dg, size);
+	sk_receive_skb(sk, skb, 0);
+
+	return VMCI_SUCCESS;
+}
+
+static bool vmci_transport_stream_allow(struct vsock_sock *vsk, u32 cid,
+					u32 port)
+{
+	static const u32 non_socket_contexts[] = {
+		VMADDR_CID_LOCAL,
+	};
+	int i;
+
+	if (!vsock_net_mode_global(vsk))
+		return false;
+
+	BUILD_BUG_ON(sizeof(cid) != sizeof(*non_socket_contexts));
+
+	for (i = 0; i < ARRAY_SIZE(non_socket_contexts); i++) {
+		if (cid == non_socket_contexts[i])
+			return false;
+	}
+
+	return true;
+}
+
+/* This is invoked as part of a tasklet that's scheduled when the VMCI
+ * interrupt fires.  This is run in bottom-half context but it defers most of
+ * its work to the packet handling work queue.
+ */
+
+static int vmci_transport_recv_stream_cb(void *data, struct vmci_datagram *dg)
+{
+	struct sock *sk;
+	struct sockaddr_vm dst;
+	struct sockaddr_vm src;
+	struct vmci_transport_packet *pkt;
+	struct vsock_sock *vsk;
+	bool bh_process_pkt;
+	int err;
+
+	sk = NULL;
+	err = VMCI_SUCCESS;
+	bh_process_pkt = false;
+
+	/* Ignore incoming packets from resources that aren't vsock
+	 * implementations.
+	 */
+	if (vmci_transport_peer_rid(dg->src.context) != dg->src.resource)
+		return VMCI_ERROR_NO_ACCESS;
+
+	if (VMCI_DG_SIZE(dg) < sizeof(*pkt))
+		/* Drop datagrams that do not contain full VSock packets. */
+		return VMCI_ERROR_INVALID_ARGS;
+
+	pkt = (struct vmci_transport_packet *)dg;
+
+	/* Find the socket that should handle this packet.  First we look for a
+	 * connected socket and if there is none we look for a socket bound to
+	 * the destintation address.
+	 */
+	vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port);
+	vsock_addr_init(&dst, pkt->dg.dst.context, pkt->dst_port);
+
+	sk = vsock_find_connected_socket(&src, &dst);
+	if (!sk) {
+		sk = vsock_find_bound_socket(&dst);
+		if (!sk) {
+			/* We could not find a socket for this specified
+			 * address.  If this packet is a RST, we just drop it.
+			 * If it is another packet, we send a RST.  Note that
+			 * we do not send a RST reply to RSTs so that we do not
+			 * continually send RSTs between two endpoints.
+			 *
+			 * Note that since this is a reply, dst is src and src
+			 * is dst.
+			 */
+			if (vmci_transport_send_reset_bh(&dst, &src, pkt) < 0)
+				pr_err("unable to send reset\n");
+
+			err = VMCI_ERROR_NOT_FOUND;
+			goto out;
+		}
+	}
+
+	/* If the received packet type is beyond all types known to this
+	 * implementation, reply with an invalid message.  Hopefully this will
+	 * help when implementing backwards compatibility in the future.
+	 */
+	if (pkt->type >= VMCI_TRANSPORT_PACKET_TYPE_MAX) {
+		vmci_transport_send_invalid_bh(&dst, &src);
+		err = VMCI_ERROR_INVALID_ARGS;
+		goto out;
+	}
+
+	/* This handler is privileged when this module is running on the host.
+	 * We will get datagram connect requests from all endpoints (even VMs
+	 * that are in a restricted context). If we get one from a restricted
+	 * context then the destination socket must be trusted.
+	 *
+	 * NOTE: We access the socket struct without holding the lock here.
+	 * This is ok because the field we are interested is never modified
+	 * outside of the create and destruct socket functions.
+	 */
+	vsk = vsock_sk(sk);
+	if (!vmci_transport_allow_dgram(vsk, pkt->dg.src.context)) {
+		err = VMCI_ERROR_NO_ACCESS;
+		goto out;
+	}
+
+	/* Ignore incoming packets from contexts without sockets. */
+	if (!vmci_transport_stream_allow(vsk, dg->src.context, -1)) {
+		err = VMCI_ERROR_NO_ACCESS;
+		goto out;
+	}
+
+	/* We do most everything in a work queue, but let's fast path the
+	 * notification of reads and writes to help data transfer performance.
+	 * We can only do this if there is no process context code executing
+	 * for this socket since that may change the state.
+	 */
+	bh_lock_sock(sk);
+
+	if (!sock_owned_by_user(sk)) {
+		/* The local context ID may be out of date, update it. */
+		vsk->local_addr.svm_cid = dst.svm_cid;
+
+		if (sk->sk_state == TCP_ESTABLISHED)
+			vmci_trans(vsk)->notify_ops->handle_notify_pkt(
+					sk, pkt, true, &dst, &src,
+					&bh_process_pkt);
+	}
+
+	bh_unlock_sock(sk);
+
+	if (!bh_process_pkt) {
+		struct vmci_transport_recv_pkt_info *recv_pkt_info;
+
+		recv_pkt_info = kmalloc_obj(*recv_pkt_info, GFP_ATOMIC);
+		if (!recv_pkt_info) {
+			if (vmci_transport_send_reset_bh(&dst, &src, pkt) < 0)
+				pr_err("unable to send reset\n");
+
+			err = VMCI_ERROR_NO_MEM;
+			goto out;
+		}
+
+		recv_pkt_info->sk = sk;
+		memcpy(&recv_pkt_info->pkt, pkt, sizeof(recv_pkt_info->pkt));
+		INIT_WORK(&recv_pkt_info->work, vmci_transport_recv_pkt_work);
+
+		schedule_work(&recv_pkt_info->work);
+		/* Clear sk so that the reference count incremented by one of
+		 * the Find functions above is not decremented below.  We need
+		 * that reference count for the packet handler we've scheduled
+		 * to run.
+		 */
+		sk = NULL;
+	}
+
+out:
+	if (sk)
+		sock_put(sk);
+
+	return err;
+}
+
+static void vmci_transport_handle_detach(struct sock *sk)
+{
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+	if (!vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle)) {
+		sock_set_flag(sk, SOCK_DONE);
+
+		/* On a detach the peer will not be sending or receiving
+		 * anymore.
+		 */
+		WRITE_ONCE(vsk->peer_shutdown, SHUTDOWN_MASK);
+
+		/* We should not be sending anymore since the peer won't be
+		 * there to receive, but we can still receive if there is data
+		 * left in our consume queue. If the local endpoint is a host,
+		 * we can't call vsock_stream_has_data, since that may block,
+		 * but a host endpoint can't read data once the VM has
+		 * detached, so there is no available data in that case.
+		 */
+		if (vsk->local_addr.svm_cid == VMADDR_CID_HOST ||
+		    vsock_stream_has_data(vsk) <= 0) {
+			if (sk->sk_state == TCP_SYN_SENT) {
+				/* The peer may detach from a queue pair while
+				 * we are still in the connecting state, i.e.,
+				 * if the peer VM is killed after attaching to
+				 * a queue pair, but before we complete the
+				 * handshake. In that case, we treat the detach
+				 * event like a reset.
+				 */
+
+				sk->sk_state = TCP_CLOSE;
+				sk->sk_err = ECONNRESET;
+				sk_error_report(sk);
+				return;
+			}
+			sk->sk_state = TCP_CLOSE;
+		}
+		sk->sk_state_change(sk);
+	}
+}
+
+static void vmci_transport_peer_detach_cb(u32 sub_id,
+					  const struct vmci_event_data *e_data,
+					  void *client_data)
+{
+	struct vmci_transport *trans = client_data;
+	const struct vmci_event_payload_qp *e_payload;
+
+	e_payload = vmci_event_data_const_payload(e_data);
+
+	/* XXX This is lame, we should provide a way to lookup sockets by
+	 * qp_handle.
+	 */
+	if (vmci_handle_is_invalid(e_payload->handle) ||
+	    !vmci_handle_is_equal(trans->qp_handle, e_payload->handle))
+		return;
+
+	/* We don't ask for delayed CBs when we subscribe to this event (we
+	 * pass 0 as flags to vmci_event_subscribe()).  VMCI makes no
+	 * guarantees in that case about what context we might be running in,
+	 * so it could be BH or process, blockable or non-blockable.  So we
+	 * need to account for all possible contexts here.
+	 */
+	spin_lock_bh(&trans->lock);
+	if (!trans->sk)
+		goto out;
+
+	/* Apart from here, trans->lock is only grabbed as part of sk destruct,
+	 * where trans->sk isn't locked.
+	 */
+	bh_lock_sock(trans->sk);
+
+	vmci_transport_handle_detach(trans->sk);
+
+	bh_unlock_sock(trans->sk);
+ out:
+	spin_unlock_bh(&trans->lock);
+}
+
+static void vmci_transport_qp_resumed_cb(u32 sub_id,
+					 const struct vmci_event_data *e_data,
+					 void *client_data)
+{
+	vsock_for_each_connected_socket(&vmci_transport,
+					vmci_transport_handle_detach);
+}
+
+static void vmci_transport_recv_pkt_work(struct work_struct *work)
+{
+	struct vmci_transport_recv_pkt_info *recv_pkt_info;
+	struct vmci_transport_packet *pkt;
+	struct sock *sk;
+
+	recv_pkt_info =
+		container_of(work, struct vmci_transport_recv_pkt_info, work);
+	sk = recv_pkt_info->sk;
+	pkt = &recv_pkt_info->pkt;
+
+	lock_sock(sk);
+
+	/* The local context ID may be out of date. */
+	vsock_sk(sk)->local_addr.svm_cid = pkt->dg.dst.context;
+
+	switch (sk->sk_state) {
+	case TCP_LISTEN:
+		vmci_transport_recv_listen(sk, pkt);
+		break;
+	case TCP_SYN_SENT:
+		/* Processing of pending connections for servers goes through
+		 * the listening socket, so see vmci_transport_recv_listen()
+		 * for that path.
+		 */
+		vmci_transport_recv_connecting_client(sk, pkt);
+		break;
+	case TCP_ESTABLISHED:
+		vmci_transport_recv_connected(sk, pkt);
+		break;
+	default:
+		/* Because this function does not run in the same context as
+		 * vmci_transport_recv_stream_cb it is possible that the
+		 * socket has closed. We need to let the other side know or it
+		 * could be sitting in a connect and hang forever. Send a
+		 * reset to prevent that.
+		 */
+		vmci_transport_send_reset(sk, pkt);
+		break;
+	}
+
+	release_sock(sk);
+	kfree(recv_pkt_info);
+	/* Release reference obtained in the stream callback when we fetched
+	 * this socket out of the bound or connected list.
+	 */
+	sock_put(sk);
+}
+
+static int vmci_transport_recv_listen(struct sock *sk,
+				      struct vmci_transport_packet *pkt)
+{
+	struct sock *pending;
+	struct vsock_sock *vpending;
+	int err;
+	u64 qp_size;
+	bool old_request = false;
+	bool old_pkt_proto = false;
+
+	/* Because we are in the listen state, we could be receiving a packet
+	 * for ourself or any previous connection requests that we received.
+	 * If it's the latter, we try to find a socket in our list of pending
+	 * connections and, if we do, call the appropriate handler for the
+	 * state that socket is in.  Otherwise we try to service the
+	 * connection request.
+	 */
+	pending = vmci_transport_get_pending(sk, pkt);
+	if (pending) {
+		lock_sock(pending);
+
+		/* The local context ID may be out of date. */
+		vsock_sk(pending)->local_addr.svm_cid = pkt->dg.dst.context;
+
+		switch (pending->sk_state) {
+		case TCP_SYN_SENT:
+			err = vmci_transport_recv_connecting_server(sk,
+								    pending,
+								    pkt);
+			break;
+		default:
+			vmci_transport_send_reset(pending, pkt);
+			err = -EINVAL;
+		}
+
+		if (err < 0)
+			vsock_remove_pending(sk, pending);
+
+		release_sock(pending);
+		vmci_transport_release_pending(pending);
+
+		return err;
+	}
+
+	/* The listen state only accepts connection requests.  Reply with a
+	 * reset unless we received a reset.
+	 */
+
+	if (!(pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST ||
+	      pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST2)) {
+		vmci_transport_reply_reset(pkt);
+		return -EINVAL;
+	}
+
+	if (pkt->u.size == 0) {
+		vmci_transport_reply_reset(pkt);
+		return -EINVAL;
+	}
+
+	/* If this socket can't accommodate this connection request, we send a
+	 * reset.  Otherwise we create and initialize a child socket and reply
+	 * with a connection negotiation.
+	 */
+	if (sk_acceptq_is_full(sk)) {
+		vmci_transport_reply_reset(pkt);
+		return -ECONNREFUSED;
+	}
+
+	pending = vsock_create_connected(sk);
+	if (!pending) {
+		vmci_transport_send_reset(sk, pkt);
+		return -ENOMEM;
+	}
+
+	vpending = vsock_sk(pending);
+
+	vsock_addr_init(&vpending->local_addr, pkt->dg.dst.context,
+			pkt->dst_port);
+	vsock_addr_init(&vpending->remote_addr, pkt->dg.src.context,
+			pkt->src_port);
+
+	err = vsock_assign_transport(vpending, vsock_sk(sk));
+	/* Transport assigned (looking at remote_addr) must be the same
+	 * where we received the request.
+	 */
+	if (err || !vmci_check_transport(vpending)) {
+		vmci_transport_send_reset(sk, pkt);
+		sock_put(pending);
+		return err;
+	}
+
+	/* If the proposed size fits within our min/max, accept it. Otherwise
+	 * propose our own size.
+	 */
+	if (pkt->u.size >= vpending->buffer_min_size &&
+	    pkt->u.size <= vpending->buffer_max_size) {
+		qp_size = pkt->u.size;
+	} else {
+		qp_size = vpending->buffer_size;
+	}
+
+	/* Figure out if we are using old or new requests based on the
+	 * overrides pkt types sent by our peer.
+	 */
+	if (vmci_transport_old_proto_override(&old_pkt_proto)) {
+		old_request = old_pkt_proto;
+	} else {
+		if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST)
+			old_request = true;
+		else if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST2)
+			old_request = false;
+
+	}
+
+	if (old_request) {
+		/* Handle a REQUEST (or override) */
+		u16 version = VSOCK_PROTO_INVALID;
+		if (vmci_transport_proto_to_notify_struct(
+			pending, &version, true))
+			err = vmci_transport_send_negotiate(pending, qp_size);
+		else
+			err = -EINVAL;
+
+	} else {
+		/* Handle a REQUEST2 (or override) */
+		int proto_int = pkt->proto;
+		int pos;
+		u16 active_proto_version = 0;
+
+		/* The list of possible protocols is the intersection of all
+		 * protocols the client supports ... plus all the protocols we
+		 * support.
+		 */
+		proto_int &= vmci_transport_new_proto_supported_versions();
+
+		/* We choose the highest possible protocol version and use that
+		 * one.
+		 */
+		pos = fls(proto_int);
+		if (pos) {
+			active_proto_version = (1 << (pos - 1));
+			if (vmci_transport_proto_to_notify_struct(
+				pending, &active_proto_version, false))
+				err = vmci_transport_send_negotiate2(pending,
+							qp_size,
+							active_proto_version);
+			else
+				err = -EINVAL;
+
+		} else {
+			err = -EINVAL;
+		}
+	}
+
+	if (err < 0) {
+		vmci_transport_send_reset(sk, pkt);
+		sock_put(pending);
+		err = vmci_transport_error_to_vsock_error(err);
+		goto out;
+	}
+
+	vsock_add_pending(sk, pending);
+
+	pending->sk_state = TCP_SYN_SENT;
+	vmci_trans(vpending)->produce_size =
+		vmci_trans(vpending)->consume_size = qp_size;
+	vpending->buffer_size = qp_size;
+
+	vmci_trans(vpending)->notify_ops->process_request(pending);
+
+	/* We might never receive another message for this socket and it's not
+	 * connected to any process, so we have to ensure it gets cleaned up
+	 * ourself.  Our delayed work function will take care of that.  Note
+	 * that we do not ever cancel this function since we have few
+	 * guarantees about its state when calling cancel_delayed_work().
+	 * Instead we hold a reference on the socket for that function and make
+	 * it capable of handling cases where it needs to do nothing but
+	 * release that reference.
+	 */
+	vpending->listener = sk;
+	sock_hold(sk);
+	sock_hold(pending);
+	schedule_delayed_work(&vpending->pending_work, HZ);
+
+out:
+	return err;
+}
+
+static int
+vmci_transport_recv_connecting_server(struct sock *listener,
+				      struct sock *pending,
+				      struct vmci_transport_packet *pkt)
+{
+	struct vsock_sock *vpending;
+	struct vmci_handle handle;
+	struct vmci_qp *qpair;
+	bool is_local;
+	u32 flags;
+	u32 detach_sub_id;
+	int err;
+	int skerr;
+
+	vpending = vsock_sk(pending);
+	detach_sub_id = VMCI_INVALID_ID;
+
+	switch (pkt->type) {
+	case VMCI_TRANSPORT_PACKET_TYPE_OFFER:
+		if (vmci_handle_is_invalid(pkt->u.handle)) {
+			vmci_transport_send_reset(pending, pkt);
+			skerr = EPROTO;
+			err = -EINVAL;
+			goto destroy;
+		}
+		break;
+	default:
+		/* Close and cleanup the connection. */
+		vmci_transport_send_reset(pending, pkt);
+		skerr = EPROTO;
+		err = -EINVAL;
+		goto destroy;
+	}
+
+	/* In order to complete the connection we need to attach to the offered
+	 * queue pair and send an attach notification.  We also subscribe to the
+	 * detach event so we know when our peer goes away, and we do that
+	 * before attaching so we don't miss an event.  If all this succeeds,
+	 * we update our state and wakeup anything waiting in accept() for a
+	 * connection.
+	 */
+
+	/* We don't care about attach since we ensure the other side has
+	 * attached by specifying the ATTACH_ONLY flag below.
+	 */
+	err = vmci_event_subscribe(VMCI_EVENT_QP_PEER_DETACH,
+				   vmci_transport_peer_detach_cb,
+				   vmci_trans(vpending), &detach_sub_id);
+	if (err < VMCI_SUCCESS) {
+		vmci_transport_send_reset(pending, pkt);
+		err = vmci_transport_error_to_vsock_error(err);
+		skerr = -err;
+		goto destroy;
+	}
+
+	vmci_trans(vpending)->detach_sub_id = detach_sub_id;
+
+	/* Now attach to the queue pair the client created. */
+	handle = pkt->u.handle;
+
+	/* vpending->local_addr always has a context id so we do not need to
+	 * worry about VMADDR_CID_ANY in this case.
+	 */
+	is_local =
+	    vpending->remote_addr.svm_cid == vpending->local_addr.svm_cid;
+	flags = VMCI_QPFLAG_ATTACH_ONLY;
+	flags |= is_local ? VMCI_QPFLAG_LOCAL : 0;
+
+	err = vmci_transport_queue_pair_alloc(
+					&qpair,
+					&handle,
+					vmci_trans(vpending)->produce_size,
+					vmci_trans(vpending)->consume_size,
+					pkt->dg.src.context,
+					flags,
+					vmci_transport_is_trusted(
+						vpending,
+						vpending->remote_addr.svm_cid));
+	if (err < 0) {
+		vmci_transport_send_reset(pending, pkt);
+		skerr = -err;
+		goto destroy;
+	}
+
+	vmci_trans(vpending)->qp_handle = handle;
+	vmci_trans(vpending)->qpair = qpair;
+
+	/* When we send the attach message, we must be ready to handle incoming
+	 * control messages on the newly connected socket. So we move the
+	 * pending socket to the connected state before sending the attach
+	 * message. Otherwise, an incoming packet triggered by the attach being
+	 * received by the peer may be processed concurrently with what happens
+	 * below after sending the attach message, and that incoming packet
+	 * will find the listening socket instead of the (currently) pending
+	 * socket. Note that enqueueing the socket increments the reference
+	 * count, so even if a reset comes before the connection is accepted,
+	 * the socket will be valid until it is removed from the queue.
+	 *
+	 * If we fail sending the attach below, we remove the socket from the
+	 * connected list and move the socket to TCP_CLOSE before
+	 * releasing the lock, so a pending slow path processing of an incoming
+	 * packet will not see the socket in the connected state in that case.
+	 */
+	pending->sk_state = TCP_ESTABLISHED;
+
+	vsock_insert_connected(vpending);
+
+	/* Notify our peer of our attach. */
+	err = vmci_transport_send_attach(pending, handle);
+	if (err < 0) {
+		vsock_remove_connected(vpending);
+		pr_err("Could not send attach\n");
+		vmci_transport_send_reset(pending, pkt);
+		err = vmci_transport_error_to_vsock_error(err);
+		skerr = -err;
+		goto destroy;
+	}
+
+	/* We have a connection. Move the now connected socket from the
+	 * listener's pending list to the accept queue so callers of accept()
+	 * can find it.
+	 */
+	vsock_pending_to_accept(listener, pending);
+
+	/* Callers of accept() will be waiting on the listening socket, not
+	 * the pending socket.
+	 */
+	listener->sk_data_ready(listener);
+
+	return 0;
+
+destroy:
+	pending->sk_err = skerr;
+	pending->sk_state = TCP_CLOSE;
+	/* As long as we drop our reference, all necessary cleanup will handle
+	 * when the cleanup function drops its reference and our destruct
+	 * implementation is called.  Note that since the listen handler will
+	 * remove pending from the pending list upon our failure, the cleanup
+	 * function won't drop the additional reference, which is why we do it
+	 * here.
+	 */
+	sock_put(pending);
+
+	return err;
+}
+
+static int
+vmci_transport_recv_connecting_client(struct sock *sk,
+				      struct vmci_transport_packet *pkt)
+{
+	struct vsock_sock *vsk;
+	int err;
+	int skerr;
+
+	vsk = vsock_sk(sk);
+
+	switch (pkt->type) {
+	case VMCI_TRANSPORT_PACKET_TYPE_ATTACH:
+		if (vmci_handle_is_invalid(pkt->u.handle) ||
+		    !vmci_handle_is_equal(pkt->u.handle,
+					  vmci_trans(vsk)->qp_handle)) {
+			skerr = EPROTO;
+			err = -EINVAL;
+			goto destroy;
+		}
+
+		/* Signify the socket is connected and wakeup the waiter in
+		 * connect(). Also place the socket in the connected table for
+		 * accounting (it can already be found since it's in the bound
+		 * table).
+		 */
+		sk->sk_state = TCP_ESTABLISHED;
+		sk->sk_socket->state = SS_CONNECTED;
+		vsock_insert_connected(vsk);
+		sk->sk_state_change(sk);
+
+		break;
+	case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE:
+	case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2:
+		if (pkt->u.size == 0
+		    || pkt->dg.src.context != vsk->remote_addr.svm_cid
+		    || pkt->src_port != vsk->remote_addr.svm_port
+		    || !vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle)
+		    || vmci_trans(vsk)->qpair
+		    || vmci_trans(vsk)->produce_size != 0
+		    || vmci_trans(vsk)->consume_size != 0
+		    || vmci_trans(vsk)->detach_sub_id != VMCI_INVALID_ID) {
+			skerr = EPROTO;
+			err = -EINVAL;
+
+			goto destroy;
+		}
+
+		err = vmci_transport_recv_connecting_client_negotiate(sk, pkt);
+		if (err) {
+			skerr = -err;
+			goto destroy;
+		}
+
+		break;
+	case VMCI_TRANSPORT_PACKET_TYPE_INVALID:
+		err = vmci_transport_recv_connecting_client_invalid(sk, pkt);
+		if (err) {
+			skerr = -err;
+			goto destroy;
+		}
+
+		break;
+	case VMCI_TRANSPORT_PACKET_TYPE_RST:
+		/* Older versions of the linux code (WS 6.5 / ESX 4.0) used to
+		 * continue processing here after they sent an INVALID packet.
+		 * This meant that we got a RST after the INVALID. We ignore a
+		 * RST after an INVALID. The common code doesn't send the RST
+		 * ... so we can hang if an old version of the common code
+		 * fails between getting a REQUEST and sending an OFFER back.
+		 * Not much we can do about it... except hope that it doesn't
+		 * happen.
+		 */
+		if (vsk->ignore_connecting_rst) {
+			vsk->ignore_connecting_rst = false;
+		} else {
+			skerr = ECONNRESET;
+			err = 0;
+			goto destroy;
+		}
+
+		break;
+	default:
+		/* Close and cleanup the connection. */
+		skerr = EPROTO;
+		err = -EINVAL;
+		goto destroy;
+	}
+
+	return 0;
+
+destroy:
+	vmci_transport_send_reset(sk, pkt);
+
+	sk->sk_state = TCP_CLOSE;
+	sk->sk_err = skerr;
+	sk_error_report(sk);
+	return err;
+}
+
+static int vmci_transport_recv_connecting_client_negotiate(
+					struct sock *sk,
+					struct vmci_transport_packet *pkt)
+{
+	int err;
+	struct vsock_sock *vsk;
+	struct vmci_handle handle;
+	struct vmci_qp *qpair;
+	u32 detach_sub_id;
+	bool is_local;
+	u32 flags;
+	bool old_proto = true;
+	bool old_pkt_proto;
+	u16 version;
+
+	vsk = vsock_sk(sk);
+	handle = VMCI_INVALID_HANDLE;
+	detach_sub_id = VMCI_INVALID_ID;
+
+	/* If we have gotten here then we should be past the point where old
+	 * linux vsock could have sent the bogus rst.
+	 */
+	vsk->sent_request = false;
+	vsk->ignore_connecting_rst = false;
+
+	/* Verify that we're OK with the proposed queue pair size */
+	if (pkt->u.size < vsk->buffer_min_size ||
+	    pkt->u.size > vsk->buffer_max_size) {
+		err = -EINVAL;
+		goto destroy;
+	}
+
+	/* At this point we know the CID the peer is using to talk to us. */
+
+	if (vsk->local_addr.svm_cid == VMADDR_CID_ANY)
+		vsk->local_addr.svm_cid = pkt->dg.dst.context;
+
+	/* Setup the notify ops to be the highest supported version that both
+	 * the server and the client support.
+	 */
+
+	if (vmci_transport_old_proto_override(&old_pkt_proto)) {
+		old_proto = old_pkt_proto;
+	} else {
+		if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE)
+			old_proto = true;
+		else if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2)
+			old_proto = false;
+
+	}
+
+	if (old_proto)
+		version = VSOCK_PROTO_INVALID;
+	else
+		version = pkt->proto;
+
+	if (!vmci_transport_proto_to_notify_struct(sk, &version, old_proto)) {
+		err = -EINVAL;
+		goto destroy;
+	}
+
+	/* Subscribe to detach events first.
+	 *
+	 * XXX We attach once for each queue pair created for now so it is easy
+	 * to find the socket (it's provided), but later we should only
+	 * subscribe once and add a way to lookup sockets by queue pair handle.
+	 */
+	err = vmci_event_subscribe(VMCI_EVENT_QP_PEER_DETACH,
+				   vmci_transport_peer_detach_cb,
+				   vmci_trans(vsk), &detach_sub_id);
+	if (err < VMCI_SUCCESS) {
+		err = vmci_transport_error_to_vsock_error(err);
+		goto destroy;
+	}
+
+	/* Make VMCI select the handle for us. */
+	handle = VMCI_INVALID_HANDLE;
+	is_local = vsk->remote_addr.svm_cid == vsk->local_addr.svm_cid;
+	flags = is_local ? VMCI_QPFLAG_LOCAL : 0;
+
+	err = vmci_transport_queue_pair_alloc(&qpair,
+					      &handle,
+					      pkt->u.size,
+					      pkt->u.size,
+					      vsk->remote_addr.svm_cid,
+					      flags,
+					      vmci_transport_is_trusted(
+						  vsk,
+						  vsk->
+						  remote_addr.svm_cid));
+	if (err < 0)
+		goto destroy;
+
+	err = vmci_transport_send_qp_offer(sk, handle);
+	if (err < 0) {
+		err = vmci_transport_error_to_vsock_error(err);
+		goto destroy;
+	}
+
+	vmci_trans(vsk)->qp_handle = handle;
+	vmci_trans(vsk)->qpair = qpair;
+
+	vmci_trans(vsk)->produce_size = vmci_trans(vsk)->consume_size =
+		pkt->u.size;
+
+	vmci_trans(vsk)->detach_sub_id = detach_sub_id;
+
+	vmci_trans(vsk)->notify_ops->process_negotiate(sk);
+
+	return 0;
+
+destroy:
+	if (detach_sub_id != VMCI_INVALID_ID)
+		vmci_event_unsubscribe(detach_sub_id);
+
+	if (!vmci_handle_is_invalid(handle))
+		vmci_qpair_detach(&qpair);
+
+	return err;
+}
+
+static int
+vmci_transport_recv_connecting_client_invalid(struct sock *sk,
+					      struct vmci_transport_packet *pkt)
+{
+	int err = 0;
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (vsk->sent_request) {
+		vsk->sent_request = false;
+		vsk->ignore_connecting_rst = true;
+
+		err = vmci_transport_send_conn_request(sk, vsk->buffer_size);
+		if (err < 0)
+			err = vmci_transport_error_to_vsock_error(err);
+		else
+			err = 0;
+
+	}
+
+	return err;
+}
+
+static int vmci_transport_recv_connected(struct sock *sk,
+					 struct vmci_transport_packet *pkt)
+{
+	struct vsock_sock *vsk;
+	bool pkt_processed = false;
+
+	/* In cases where we are closing the connection, it's sufficient to
+	 * mark the state change (and maybe error) and wake up any waiting
+	 * threads. Since this is a connected socket, it's owned by a user
+	 * process and will be cleaned up when the failure is passed back on
+	 * the current or next system call.  Our system call implementations
+	 * must therefore check for error and state changes on entry and when
+	 * being awoken.
+	 */
+	switch (pkt->type) {
+	case VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN:
+		if (pkt->u.mode) {
+			vsk = vsock_sk(sk);
+
+			WRITE_ONCE(vsk->peer_shutdown,
+				   READ_ONCE(vsk->peer_shutdown) |
+				   pkt->u.mode);
+			sk->sk_state_change(sk);
+		}
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_RST:
+		vsk = vsock_sk(sk);
+		/* It is possible that we sent our peer a message (e.g a
+		 * WAITING_READ) right before we got notified that the peer had
+		 * detached. If that happens then we can get a RST pkt back
+		 * from our peer even though there is data available for us to
+		 * read. In that case, don't shutdown the socket completely but
+		 * instead allow the local client to finish reading data off
+		 * the queuepair. Always treat a RST pkt in connected mode like
+		 * a clean shutdown.
+		 */
+		sock_set_flag(sk, SOCK_DONE);
+		WRITE_ONCE(vsk->peer_shutdown, SHUTDOWN_MASK);
+		if (vsock_stream_has_data(vsk) <= 0)
+			sk->sk_state = TCP_CLOSING;
+
+		sk->sk_state_change(sk);
+		break;
+
+	default:
+		vsk = vsock_sk(sk);
+		vmci_trans(vsk)->notify_ops->handle_notify_pkt(
+				sk, pkt, false, NULL, NULL,
+				&pkt_processed);
+		if (!pkt_processed)
+			return -EINVAL;
+
+		break;
+	}
+
+	return 0;
+}
+
+static int vmci_transport_socket_init(struct vsock_sock *vsk,
+				      struct vsock_sock *psk)
+{
+	vsk->trans = kmalloc_obj(struct vmci_transport);
+	if (!vsk->trans)
+		return -ENOMEM;
+
+	vmci_trans(vsk)->dg_handle = VMCI_INVALID_HANDLE;
+	vmci_trans(vsk)->qp_handle = VMCI_INVALID_HANDLE;
+	vmci_trans(vsk)->qpair = NULL;
+	vmci_trans(vsk)->produce_size = vmci_trans(vsk)->consume_size = 0;
+	vmci_trans(vsk)->detach_sub_id = VMCI_INVALID_ID;
+	vmci_trans(vsk)->notify_ops = NULL;
+	INIT_LIST_HEAD(&vmci_trans(vsk)->elem);
+	vmci_trans(vsk)->sk = &vsk->sk;
+	spin_lock_init(&vmci_trans(vsk)->lock);
+
+	return 0;
+}
+
+static void vmci_transport_free_resources(struct list_head *transport_list)
+{
+	while (!list_empty(transport_list)) {
+		struct vmci_transport *transport =
+		    list_first_entry(transport_list, struct vmci_transport,
+				     elem);
+		list_del(&transport->elem);
+
+		if (transport->detach_sub_id != VMCI_INVALID_ID) {
+			vmci_event_unsubscribe(transport->detach_sub_id);
+			transport->detach_sub_id = VMCI_INVALID_ID;
+		}
+
+		if (!vmci_handle_is_invalid(transport->qp_handle)) {
+			vmci_qpair_detach(&transport->qpair);
+			transport->qp_handle = VMCI_INVALID_HANDLE;
+			transport->produce_size = 0;
+			transport->consume_size = 0;
+		}
+
+		kfree(transport);
+	}
+}
+
+static void vmci_transport_cleanup(struct work_struct *work)
+{
+	LIST_HEAD(pending);
+
+	spin_lock_bh(&vmci_transport_cleanup_lock);
+	list_replace_init(&vmci_transport_cleanup_list, &pending);
+	spin_unlock_bh(&vmci_transport_cleanup_lock);
+	vmci_transport_free_resources(&pending);
+}
+
+static void vmci_transport_destruct(struct vsock_sock *vsk)
+{
+	/* transport can be NULL if we hit a failure at init() time */
+	if (!vmci_trans(vsk))
+		return;
+
+	/* Ensure that the detach callback doesn't use the sk/vsk
+	 * we are about to destruct.
+	 */
+	spin_lock_bh(&vmci_trans(vsk)->lock);
+	vmci_trans(vsk)->sk = NULL;
+	spin_unlock_bh(&vmci_trans(vsk)->lock);
+
+	if (vmci_trans(vsk)->notify_ops)
+		vmci_trans(vsk)->notify_ops->socket_destruct(vsk);
+
+	spin_lock_bh(&vmci_transport_cleanup_lock);
+	list_add(&vmci_trans(vsk)->elem, &vmci_transport_cleanup_list);
+	spin_unlock_bh(&vmci_transport_cleanup_lock);
+	schedule_work(&vmci_transport_cleanup_work);
+
+	vsk->trans = NULL;
+}
+
+static void vmci_transport_release(struct vsock_sock *vsk)
+{
+	vsock_remove_sock(vsk);
+
+	if (!vmci_handle_is_invalid(vmci_trans(vsk)->dg_handle)) {
+		vmci_datagram_destroy_handle(vmci_trans(vsk)->dg_handle);
+		vmci_trans(vsk)->dg_handle = VMCI_INVALID_HANDLE;
+	}
+}
+
+static int vmci_transport_dgram_bind(struct vsock_sock *vsk,
+				     struct sockaddr_vm *addr)
+{
+	u32 port;
+	u32 flags;
+	int err;
+
+	/* VMCI will select a resource ID for us if we provide
+	 * VMCI_INVALID_ID.
+	 */
+	port = addr->svm_port == VMADDR_PORT_ANY ?
+			VMCI_INVALID_ID : addr->svm_port;
+
+	if (port <= LAST_RESERVED_PORT && !capable(CAP_NET_BIND_SERVICE))
+		return -EACCES;
+
+	flags = addr->svm_cid == VMADDR_CID_ANY ?
+				VMCI_FLAG_ANYCID_DG_HND : 0;
+
+	err = vmci_transport_datagram_create_hnd(port, flags,
+						 vmci_transport_recv_dgram_cb,
+						 &vsk->sk,
+						 &vmci_trans(vsk)->dg_handle);
+	if (err < VMCI_SUCCESS)
+		return vmci_transport_error_to_vsock_error(err);
+	vsock_addr_init(&vsk->local_addr, addr->svm_cid,
+			vmci_trans(vsk)->dg_handle.resource);
+
+	return 0;
+}
+
+static int vmci_transport_dgram_enqueue(
+	struct vsock_sock *vsk,
+	struct sockaddr_vm *remote_addr,
+	struct msghdr *msg,
+	size_t len)
+{
+	int err;
+	struct vmci_datagram *dg;
+
+	if (len > VMCI_MAX_DG_PAYLOAD_SIZE)
+		return -EMSGSIZE;
+
+	if (!vmci_transport_allow_dgram(vsk, remote_addr->svm_cid))
+		return -EPERM;
+
+	/* Allocate a buffer for the user's message and our packet header. */
+	dg = kmalloc(len + sizeof(*dg), GFP_KERNEL);
+	if (!dg)
+		return -ENOMEM;
+
+	err = memcpy_from_msg(VMCI_DG_PAYLOAD(dg), msg, len);
+	if (err) {
+		kfree(dg);
+		return err;
+	}
+
+	dg->dst = vmci_make_handle(remote_addr->svm_cid,
+				   remote_addr->svm_port);
+	dg->src = vmci_make_handle(vsk->local_addr.svm_cid,
+				   vsk->local_addr.svm_port);
+	dg->payload_size = len;
+
+	err = vmci_datagram_send(dg);
+	kfree(dg);
+	if (err < 0)
+		return vmci_transport_error_to_vsock_error(err);
+
+	return err - sizeof(*dg);
+}
+
+static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
+					struct msghdr *msg, size_t len,
+					int flags)
+{
+	int err;
+	struct vmci_datagram *dg;
+	size_t payload_len;
+	struct sk_buff *skb;
+
+	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
+		return -EOPNOTSUPP;
+
+	/* Retrieve the head sk_buff from the socket's receive queue. */
+	err = 0;
+	skb = skb_recv_datagram(&vsk->sk, flags, &err);
+	if (!skb)
+		return err;
+
+	dg = (struct vmci_datagram *)skb->data;
+	if (!dg)
+		/* err is 0, meaning we read zero bytes. */
+		goto out;
+
+	payload_len = dg->payload_size;
+	/* Ensure the sk_buff matches the payload size claimed in the packet. */
+	if (payload_len != skb->len - sizeof(*dg)) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (payload_len > len) {
+		payload_len = len;
+		msg->msg_flags |= MSG_TRUNC;
+	}
+
+	/* Place the datagram payload in the user's iovec. */
+	err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
+	if (err)
+		goto out;
+
+	if (msg->msg_name) {
+		/* Provide the address of the sender. */
+		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
+		vsock_addr_init(vm_addr, dg->src.context, dg->src.resource);
+		msg->msg_namelen = sizeof(*vm_addr);
+	}
+	err = payload_len;
+
+out:
+	skb_free_datagram(&vsk->sk, skb);
+	return err;
+}
+
+static bool vmci_transport_dgram_allow(struct vsock_sock *vsk, u32 cid,
+				       u32 port)
+{
+	if (!vsock_net_mode_global(vsk))
+		return false;
+
+	if (cid == VMADDR_CID_HYPERVISOR) {
+		/* Registrations of PBRPC Servers do not modify VMX/Hypervisor
+		 * state and are allowed.
+		 */
+		return port == VMCI_UNITY_PBRPC_REGISTER;
+	}
+
+	return true;
+}
+
+static int vmci_transport_connect(struct vsock_sock *vsk)
+{
+	int err;
+	bool old_pkt_proto = false;
+	struct sock *sk = &vsk->sk;
+
+	if (vmci_transport_old_proto_override(&old_pkt_proto) &&
+		old_pkt_proto) {
+		err = vmci_transport_send_conn_request(sk, vsk->buffer_size);
+		if (err < 0) {
+			sk->sk_state = TCP_CLOSE;
+			return err;
+		}
+	} else {
+		int supported_proto_versions =
+			vmci_transport_new_proto_supported_versions();
+		err = vmci_transport_send_conn_request2(sk, vsk->buffer_size,
+				supported_proto_versions);
+		if (err < 0) {
+			sk->sk_state = TCP_CLOSE;
+			return err;
+		}
+
+		vsk->sent_request = true;
+	}
+
+	return err;
+}
+
+static ssize_t vmci_transport_stream_dequeue(
+	struct vsock_sock *vsk,
+	struct msghdr *msg,
+	size_t len,
+	int flags)
+{
+	ssize_t err;
+
+	if (flags & MSG_PEEK)
+		err = vmci_qpair_peekv(vmci_trans(vsk)->qpair, msg, len, 0);
+	else
+		err = vmci_qpair_dequev(vmci_trans(vsk)->qpair, msg, len, 0);
+
+	if (err < 0)
+		err = -ENOMEM;
+
+	return err;
+}
+
+static ssize_t vmci_transport_stream_enqueue(
+	struct vsock_sock *vsk,
+	struct msghdr *msg,
+	size_t len)
+{
+	ssize_t err;
+
+	err = vmci_qpair_enquev(vmci_trans(vsk)->qpair, msg, len, 0);
+	if (err < 0)
+		err = -ENOMEM;
+
+	return err;
+}
+
+static s64 vmci_transport_stream_has_data(struct vsock_sock *vsk)
+{
+	return vmci_qpair_consume_buf_ready(vmci_trans(vsk)->qpair);
+}
+
+static s64 vmci_transport_stream_has_space(struct vsock_sock *vsk)
+{
+	return vmci_qpair_produce_free_space(vmci_trans(vsk)->qpair);
+}
+
+static u64 vmci_transport_stream_rcvhiwat(struct vsock_sock *vsk)
+{
+	return vmci_trans(vsk)->consume_size;
+}
+
+static bool vmci_transport_stream_is_active(struct vsock_sock *vsk)
+{
+	return !vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle);
+}
+
+static int vmci_transport_notify_poll_in(
+	struct vsock_sock *vsk,
+	size_t target,
+	bool *data_ready_now)
+{
+	return vmci_trans(vsk)->notify_ops->poll_in(
+			&vsk->sk, target, data_ready_now);
+}
+
+static int vmci_transport_notify_poll_out(
+	struct vsock_sock *vsk,
+	size_t target,
+	bool *space_available_now)
+{
+	return vmci_trans(vsk)->notify_ops->poll_out(
+			&vsk->sk, target, space_available_now);
+}
+
+static int vmci_transport_notify_recv_init(
+	struct vsock_sock *vsk,
+	size_t target,
+	struct vsock_transport_recv_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->recv_init(
+			&vsk->sk, target,
+			(struct vmci_transport_recv_notify_data *)data);
+}
+
+static int vmci_transport_notify_recv_pre_block(
+	struct vsock_sock *vsk,
+	size_t target,
+	struct vsock_transport_recv_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->recv_pre_block(
+			&vsk->sk, target,
+			(struct vmci_transport_recv_notify_data *)data);
+}
+
+static int vmci_transport_notify_recv_pre_dequeue(
+	struct vsock_sock *vsk,
+	size_t target,
+	struct vsock_transport_recv_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->recv_pre_dequeue(
+			&vsk->sk, target,
+			(struct vmci_transport_recv_notify_data *)data);
+}
+
+static int vmci_transport_notify_recv_post_dequeue(
+	struct vsock_sock *vsk,
+	size_t target,
+	ssize_t copied,
+	bool data_read,
+	struct vsock_transport_recv_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->recv_post_dequeue(
+			&vsk->sk, target, copied, data_read,
+			(struct vmci_transport_recv_notify_data *)data);
+}
+
+static int vmci_transport_notify_send_init(
+	struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->send_init(
+			&vsk->sk,
+			(struct vmci_transport_send_notify_data *)data);
+}
+
+static int vmci_transport_notify_send_pre_block(
+	struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->send_pre_block(
+			&vsk->sk,
+			(struct vmci_transport_send_notify_data *)data);
+}
+
+static int vmci_transport_notify_send_pre_enqueue(
+	struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->send_pre_enqueue(
+			&vsk->sk,
+			(struct vmci_transport_send_notify_data *)data);
+}
+
+static int vmci_transport_notify_send_post_enqueue(
+	struct vsock_sock *vsk,
+	ssize_t written,
+	struct vsock_transport_send_notify_data *data)
+{
+	return vmci_trans(vsk)->notify_ops->send_post_enqueue(
+			&vsk->sk, written,
+			(struct vmci_transport_send_notify_data *)data);
+}
+
+static bool vmci_transport_old_proto_override(bool *old_pkt_proto)
+{
+	if (PROTOCOL_OVERRIDE != -1) {
+		if (PROTOCOL_OVERRIDE == 0)
+			*old_pkt_proto = true;
+		else
+			*old_pkt_proto = false;
+
+		pr_info("Proto override in use\n");
+		return true;
+	}
+
+	return false;
+}
+
+static bool vmci_transport_proto_to_notify_struct(struct sock *sk,
+						  u16 *proto,
+						  bool old_pkt_proto)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (old_pkt_proto) {
+		if (*proto != VSOCK_PROTO_INVALID) {
+			pr_err("Can't set both an old and new protocol\n");
+			return false;
+		}
+		vmci_trans(vsk)->notify_ops = &vmci_transport_notify_pkt_ops;
+		goto exit;
+	}
+
+	switch (*proto) {
+	case VSOCK_PROTO_PKT_ON_NOTIFY:
+		vmci_trans(vsk)->notify_ops =
+			&vmci_transport_notify_pkt_q_state_ops;
+		break;
+	default:
+		pr_err("Unknown notify protocol version\n");
+		return false;
+	}
+
+exit:
+	vmci_trans(vsk)->notify_ops->socket_init(sk);
+	return true;
+}
+
+static u16 vmci_transport_new_proto_supported_versions(void)
+{
+	if (PROTOCOL_OVERRIDE != -1)
+		return PROTOCOL_OVERRIDE;
+
+	return VSOCK_PROTO_ALL_SUPPORTED;
+}
+
+static u32 vmci_transport_get_local_cid(void)
+{
+	return vmci_get_context_id();
+}
+
+static struct vsock_transport vmci_transport = {
+	.module = THIS_MODULE,
+	.init = vmci_transport_socket_init,
+	.destruct = vmci_transport_destruct,
+	.release = vmci_transport_release,
+	.connect = vmci_transport_connect,
+	.dgram_bind = vmci_transport_dgram_bind,
+	.dgram_dequeue = vmci_transport_dgram_dequeue,
+	.dgram_enqueue = vmci_transport_dgram_enqueue,
+	.dgram_allow = vmci_transport_dgram_allow,
+	.stream_dequeue = vmci_transport_stream_dequeue,
+	.stream_enqueue = vmci_transport_stream_enqueue,
+	.stream_has_data = vmci_transport_stream_has_data,
+	.stream_has_space = vmci_transport_stream_has_space,
+	.stream_rcvhiwat = vmci_transport_stream_rcvhiwat,
+	.stream_is_active = vmci_transport_stream_is_active,
+	.stream_allow = vmci_transport_stream_allow,
+	.notify_poll_in = vmci_transport_notify_poll_in,
+	.notify_poll_out = vmci_transport_notify_poll_out,
+	.notify_recv_init = vmci_transport_notify_recv_init,
+	.notify_recv_pre_block = vmci_transport_notify_recv_pre_block,
+	.notify_recv_pre_dequeue = vmci_transport_notify_recv_pre_dequeue,
+	.notify_recv_post_dequeue = vmci_transport_notify_recv_post_dequeue,
+	.notify_send_init = vmci_transport_notify_send_init,
+	.notify_send_pre_block = vmci_transport_notify_send_pre_block,
+	.notify_send_pre_enqueue = vmci_transport_notify_send_pre_enqueue,
+	.notify_send_post_enqueue = vmci_transport_notify_send_post_enqueue,
+	.shutdown = vmci_transport_shutdown,
+	.get_local_cid = vmci_transport_get_local_cid,
+};
+
+static bool vmci_check_transport(struct vsock_sock *vsk)
+{
+	return vsk->transport == &vmci_transport;
+}
+
+static void vmci_vsock_transport_cb(bool is_host)
+{
+	int features;
+
+	if (is_host)
+		features = VSOCK_TRANSPORT_F_H2G;
+	else
+		features = VSOCK_TRANSPORT_F_G2H;
+
+	vsock_core_register(&vmci_transport, features);
+}
+
+static int __init vmci_transport_init(void)
+{
+	int err;
+
+	/* Create the datagram handle that we will use to send and receive all
+	 * VSocket control messages for this context.
+	 */
+	err = vmci_transport_datagram_create_hnd(VMCI_TRANSPORT_PACKET_RID,
+						 VMCI_FLAG_ANYCID_DG_HND,
+						 vmci_transport_recv_stream_cb,
+						 NULL,
+						 &vmci_transport_stream_handle);
+	if (err < VMCI_SUCCESS) {
+		pr_err("Unable to create datagram handle. (%d)\n", err);
+		return vmci_transport_error_to_vsock_error(err);
+	}
+	err = vmci_event_subscribe(VMCI_EVENT_QP_RESUMED,
+				   vmci_transport_qp_resumed_cb,
+				   NULL, &vmci_transport_qp_resumed_sub_id);
+	if (err < VMCI_SUCCESS) {
+		pr_err("Unable to subscribe to resumed event. (%d)\n", err);
+		err = vmci_transport_error_to_vsock_error(err);
+		vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;
+		goto err_destroy_stream_handle;
+	}
+
+	/* Register only with dgram feature, other features (H2G, G2H) will be
+	 * registered when the first host or guest becomes active.
+	 */
+	err = vsock_core_register(&vmci_transport, VSOCK_TRANSPORT_F_DGRAM);
+	if (err < 0)
+		goto err_unsubscribe;
+
+	err = vmci_register_vsock_callback(vmci_vsock_transport_cb);
+	if (err < 0)
+		goto err_unregister;
+
+	return 0;
+
+err_unregister:
+	vsock_core_unregister(&vmci_transport);
+err_unsubscribe:
+	vmci_event_unsubscribe(vmci_transport_qp_resumed_sub_id);
+err_destroy_stream_handle:
+	vmci_datagram_destroy_handle(vmci_transport_stream_handle);
+	return err;
+}
+module_init(vmci_transport_init);
+
+static void __exit vmci_transport_exit(void)
+{
+	cancel_work_sync(&vmci_transport_cleanup_work);
+	vmci_transport_free_resources(&vmci_transport_cleanup_list);
+
+	if (!vmci_handle_is_invalid(vmci_transport_stream_handle)) {
+		if (vmci_datagram_destroy_handle(
+			vmci_transport_stream_handle) != VMCI_SUCCESS)
+			pr_err("Couldn't destroy datagram handle\n");
+		vmci_transport_stream_handle = VMCI_INVALID_HANDLE;
+	}
+
+	if (vmci_transport_qp_resumed_sub_id != VMCI_INVALID_ID) {
+		vmci_event_unsubscribe(vmci_transport_qp_resumed_sub_id);
+		vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;
+	}
+
+	vmci_register_vsock_callback(NULL);
+	vsock_core_unregister(&vmci_transport);
+}
+module_exit(vmci_transport_exit);
+
+MODULE_AUTHOR("VMware, Inc.");
+MODULE_DESCRIPTION("VMCI transport for Virtual Sockets");
+MODULE_VERSION("1.0.5.0-k");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("vmware_vsock");
+MODULE_ALIAS_NETPROTO(PF_VSOCK);
diff --git a/net/vmw_vsock/vmci_transport.h b/net/vmw_vsock/vmci_transport.h
new file mode 100644
index 000000000..dbda3abab
--- /dev/null
+++ b/net/vmw_vsock/vmci_transport.h
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2013 VMware, Inc. All rights reserved.
+ */
+
+#ifndef _VMCI_TRANSPORT_H_
+#define _VMCI_TRANSPORT_H_
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+
+#include <net/vsock_addr.h>
+#include <net/af_vsock.h>
+
+/* If the packet format changes in a release then this should change too. */
+#define VMCI_TRANSPORT_PACKET_VERSION 1
+
+/* The resource ID on which control packets are sent. */
+#define VMCI_TRANSPORT_PACKET_RID 1
+
+/* The resource ID on which control packets are sent to the hypervisor. */
+#define VMCI_TRANSPORT_HYPERVISOR_PACKET_RID 15
+
+#define VSOCK_PROTO_INVALID        0
+#define VSOCK_PROTO_PKT_ON_NOTIFY (1 << 0)
+#define VSOCK_PROTO_ALL_SUPPORTED (VSOCK_PROTO_PKT_ON_NOTIFY)
+
+#define vmci_trans(_vsk) ((struct vmci_transport *)((_vsk)->trans))
+
+enum vmci_transport_packet_type {
+	VMCI_TRANSPORT_PACKET_TYPE_INVALID = 0,
+	VMCI_TRANSPORT_PACKET_TYPE_REQUEST,
+	VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE,
+	VMCI_TRANSPORT_PACKET_TYPE_OFFER,
+	VMCI_TRANSPORT_PACKET_TYPE_ATTACH,
+	VMCI_TRANSPORT_PACKET_TYPE_WROTE,
+	VMCI_TRANSPORT_PACKET_TYPE_READ,
+	VMCI_TRANSPORT_PACKET_TYPE_RST,
+	VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN,
+	VMCI_TRANSPORT_PACKET_TYPE_WAITING_WRITE,
+	VMCI_TRANSPORT_PACKET_TYPE_WAITING_READ,
+	VMCI_TRANSPORT_PACKET_TYPE_REQUEST2,
+	VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2,
+	VMCI_TRANSPORT_PACKET_TYPE_MAX
+};
+
+struct vmci_transport_waiting_info {
+	u64 generation;
+	u64 offset;
+};
+
+/* Control packet type for STREAM sockets.  DGRAMs have no control packets nor
+ * special packet header for data packets, they are just raw VMCI DGRAM
+ * messages.  For STREAMs, control packets are sent over the control channel
+ * while data is written and read directly from queue pairs with no packet
+ * format.
+ */
+struct vmci_transport_packet {
+	struct vmci_datagram dg;
+	u8 version;
+	u8 type;
+	u16 proto;
+	u32 src_port;
+	u32 dst_port;
+	u32 _reserved2;
+	union {
+		u64 size;
+		u64 mode;
+		struct vmci_handle handle;
+		struct vmci_transport_waiting_info wait;
+	} u;
+};
+
+struct vmci_transport_notify_pkt {
+	u64 write_notify_window;
+	u64 write_notify_min_window;
+	bool peer_waiting_read;
+	bool peer_waiting_write;
+	bool peer_waiting_write_detected;
+	bool sent_waiting_read;
+	bool sent_waiting_write;
+	struct vmci_transport_waiting_info peer_waiting_read_info;
+	struct vmci_transport_waiting_info peer_waiting_write_info;
+	u64 produce_q_generation;
+	u64 consume_q_generation;
+};
+
+struct vmci_transport_notify_pkt_q_state {
+	u64 write_notify_window;
+	u64 write_notify_min_window;
+	bool peer_waiting_write;
+	bool peer_waiting_write_detected;
+};
+
+union vmci_transport_notify {
+	struct vmci_transport_notify_pkt pkt;
+	struct vmci_transport_notify_pkt_q_state pkt_q_state;
+};
+
+/* Our transport-specific data. */
+struct vmci_transport {
+	/* For DGRAMs. */
+	struct vmci_handle dg_handle;
+	/* For STREAMs. */
+	struct vmci_handle qp_handle;
+	struct vmci_qp *qpair;
+	u64 produce_size;
+	u64 consume_size;
+	u32 detach_sub_id;
+	union vmci_transport_notify notify;
+	const struct vmci_transport_notify_ops *notify_ops;
+	struct list_head elem;
+	struct sock *sk;
+	spinlock_t lock; /* protects sk. */
+};
+
+int vmci_transport_send_wrote_bh(struct sockaddr_vm *dst,
+				 struct sockaddr_vm *src);
+int vmci_transport_send_read_bh(struct sockaddr_vm *dst,
+				struct sockaddr_vm *src);
+int vmci_transport_send_wrote(struct sock *sk);
+int vmci_transport_send_read(struct sock *sk);
+int vmci_transport_send_waiting_write(struct sock *sk,
+				      struct vmci_transport_waiting_info *wait);
+int vmci_transport_send_waiting_read(struct sock *sk,
+				     struct vmci_transport_waiting_info *wait);
+
+#endif
diff --git a/net/vmw_vsock/vmci_transport_notify.c b/net/vmw_vsock/vmci_transport_notify.c
new file mode 100644
index 000000000..7c3a7db13
--- /dev/null
+++ b/net/vmw_vsock/vmci_transport_notify.c
@@ -0,0 +1,672 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2009-2013 VMware, Inc. All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <net/sock.h>
+
+#include "vmci_transport_notify.h"
+
+#define PKT_FIELD(vsk, field_name) (vmci_trans(vsk)->notify.pkt.field_name)
+
+static bool vmci_transport_notify_waiting_write(struct vsock_sock *vsk)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	bool retval;
+	u64 notify_limit;
+
+	if (!PKT_FIELD(vsk, peer_waiting_write))
+		return false;
+
+#ifdef VSOCK_OPTIMIZATION_FLOW_CONTROL
+	/* When the sender blocks, we take that as a sign that the sender is
+	 * faster than the receiver. To reduce the transmit rate of the sender,
+	 * we delay the sending of the read notification by decreasing the
+	 * write_notify_window. The notification is delayed until the number of
+	 * bytes used in the queue drops below the write_notify_window.
+	 */
+
+	if (!PKT_FIELD(vsk, peer_waiting_write_detected)) {
+		PKT_FIELD(vsk, peer_waiting_write_detected) = true;
+		if (PKT_FIELD(vsk, write_notify_window) < PAGE_SIZE) {
+			PKT_FIELD(vsk, write_notify_window) =
+			    PKT_FIELD(vsk, write_notify_min_window);
+		} else {
+			PKT_FIELD(vsk, write_notify_window) -= PAGE_SIZE;
+			if (PKT_FIELD(vsk, write_notify_window) <
+			    PKT_FIELD(vsk, write_notify_min_window))
+				PKT_FIELD(vsk, write_notify_window) =
+				    PKT_FIELD(vsk, write_notify_min_window);
+
+		}
+	}
+	notify_limit = vmci_trans(vsk)->consume_size -
+		PKT_FIELD(vsk, write_notify_window);
+#else
+	notify_limit = 0;
+#endif
+
+	/* For now we ignore the wait information and just see if the free
+	 * space exceeds the notify limit.  Note that improving this function
+	 * to be more intelligent will not require a protocol change and will
+	 * retain compatibility between endpoints with mixed versions of this
+	 * function.
+	 *
+	 * The notify_limit is used to delay notifications in the case where
+	 * flow control is enabled. Below the test is expressed in terms of
+	 * free space in the queue: if free_space > ConsumeSize -
+	 * write_notify_window then notify An alternate way of expressing this
+	 * is to rewrite the expression to use the data ready in the receive
+	 * queue: if write_notify_window > bufferReady then notify as
+	 * free_space == ConsumeSize - bufferReady.
+	 */
+	retval = vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair) >
+		notify_limit;
+#ifdef VSOCK_OPTIMIZATION_FLOW_CONTROL
+	if (retval) {
+		/*
+		 * Once we notify the peer, we reset the detected flag so the
+		 * next wait will again cause a decrease in the window size.
+		 */
+
+		PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+	}
+#endif
+	return retval;
+#else
+	return true;
+#endif
+}
+
+static bool vmci_transport_notify_waiting_read(struct vsock_sock *vsk)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	if (!PKT_FIELD(vsk, peer_waiting_read))
+		return false;
+
+	/* For now we ignore the wait information and just see if there is any
+	 * data for our peer to read.  Note that improving this function to be
+	 * more intelligent will not require a protocol change and will retain
+	 * compatibility between endpoints with mixed versions of this
+	 * function.
+	 */
+	return vmci_qpair_produce_buf_ready(vmci_trans(vsk)->qpair) > 0;
+#else
+	return true;
+#endif
+}
+
+static void
+vmci_transport_handle_waiting_read(struct sock *sk,
+				   struct vmci_transport_packet *pkt,
+				   bool bottom_half,
+				   struct sockaddr_vm *dst,
+				   struct sockaddr_vm *src)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, peer_waiting_read) = true;
+	memcpy(&PKT_FIELD(vsk, peer_waiting_read_info), &pkt->u.wait,
+	       sizeof(PKT_FIELD(vsk, peer_waiting_read_info)));
+
+	if (vmci_transport_notify_waiting_read(vsk)) {
+		bool sent;
+
+		if (bottom_half)
+			sent = vmci_transport_send_wrote_bh(dst, src) > 0;
+		else
+			sent = vmci_transport_send_wrote(sk) > 0;
+
+		if (sent)
+			PKT_FIELD(vsk, peer_waiting_read) = false;
+	}
+#endif
+}
+
+static void
+vmci_transport_handle_waiting_write(struct sock *sk,
+				    struct vmci_transport_packet *pkt,
+				    bool bottom_half,
+				    struct sockaddr_vm *dst,
+				    struct sockaddr_vm *src)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, peer_waiting_write) = true;
+	memcpy(&PKT_FIELD(vsk, peer_waiting_write_info), &pkt->u.wait,
+	       sizeof(PKT_FIELD(vsk, peer_waiting_write_info)));
+
+	if (vmci_transport_notify_waiting_write(vsk)) {
+		bool sent;
+
+		if (bottom_half)
+			sent = vmci_transport_send_read_bh(dst, src) > 0;
+		else
+			sent = vmci_transport_send_read(sk) > 0;
+
+		if (sent)
+			PKT_FIELD(vsk, peer_waiting_write) = false;
+	}
+#endif
+}
+
+static void
+vmci_transport_handle_read(struct sock *sk,
+			   struct vmci_transport_packet *pkt,
+			   bool bottom_half,
+			   struct sockaddr_vm *dst, struct sockaddr_vm *src)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+	PKT_FIELD(vsk, sent_waiting_write) = false;
+#endif
+
+	sk->sk_write_space(sk);
+}
+
+static bool send_waiting_read(struct sock *sk, u64 room_needed)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	struct vsock_sock *vsk;
+	struct vmci_transport_waiting_info waiting_info;
+	u64 tail;
+	u64 head;
+	u64 room_left;
+	bool ret;
+
+	vsk = vsock_sk(sk);
+
+	if (PKT_FIELD(vsk, sent_waiting_read))
+		return true;
+
+	if (PKT_FIELD(vsk, write_notify_window) <
+			vmci_trans(vsk)->consume_size)
+		PKT_FIELD(vsk, write_notify_window) =
+		    min(PKT_FIELD(vsk, write_notify_window) + PAGE_SIZE,
+			vmci_trans(vsk)->consume_size);
+
+	vmci_qpair_get_consume_indexes(vmci_trans(vsk)->qpair, &tail, &head);
+	room_left = vmci_trans(vsk)->consume_size - head;
+	if (room_needed >= room_left) {
+		waiting_info.offset = room_needed - room_left;
+		waiting_info.generation =
+		    PKT_FIELD(vsk, consume_q_generation) + 1;
+	} else {
+		waiting_info.offset = head + room_needed;
+		waiting_info.generation = PKT_FIELD(vsk, consume_q_generation);
+	}
+
+	ret = vmci_transport_send_waiting_read(sk, &waiting_info) > 0;
+	if (ret)
+		PKT_FIELD(vsk, sent_waiting_read) = true;
+
+	return ret;
+#else
+	return true;
+#endif
+}
+
+static bool send_waiting_write(struct sock *sk, u64 room_needed)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	struct vsock_sock *vsk;
+	struct vmci_transport_waiting_info waiting_info;
+	u64 tail;
+	u64 head;
+	u64 room_left;
+	bool ret;
+
+	vsk = vsock_sk(sk);
+
+	if (PKT_FIELD(vsk, sent_waiting_write))
+		return true;
+
+	vmci_qpair_get_produce_indexes(vmci_trans(vsk)->qpair, &tail, &head);
+	room_left = vmci_trans(vsk)->produce_size - tail;
+	if (room_needed + 1 >= room_left) {
+		/* Wraps around to current generation. */
+		waiting_info.offset = room_needed + 1 - room_left;
+		waiting_info.generation = PKT_FIELD(vsk, produce_q_generation);
+	} else {
+		waiting_info.offset = tail + room_needed + 1;
+		waiting_info.generation =
+		    PKT_FIELD(vsk, produce_q_generation) - 1;
+	}
+
+	ret = vmci_transport_send_waiting_write(sk, &waiting_info) > 0;
+	if (ret)
+		PKT_FIELD(vsk, sent_waiting_write) = true;
+
+	return ret;
+#else
+	return true;
+#endif
+}
+
+static int vmci_transport_send_read_notification(struct sock *sk)
+{
+	struct vsock_sock *vsk;
+	bool sent_read;
+	unsigned int retries;
+	int err;
+
+	vsk = vsock_sk(sk);
+	sent_read = false;
+	retries = 0;
+	err = 0;
+
+	if (vmci_transport_notify_waiting_write(vsk)) {
+		/* Notify the peer that we have read, retrying the send on
+		 * failure up to our maximum value.  XXX For now we just log
+		 * the failure, but later we should schedule a work item to
+		 * handle the resend until it succeeds.  That would require
+		 * keeping track of work items in the vsk and cleaning them up
+		 * upon socket close.
+		 */
+		while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
+		       !sent_read &&
+		       retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+			err = vmci_transport_send_read(sk);
+			if (err >= 0)
+				sent_read = true;
+
+			retries++;
+		}
+
+		if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS)
+			pr_err("%p unable to send read notify to peer\n", sk);
+		else
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+			PKT_FIELD(vsk, peer_waiting_write) = false;
+#endif
+
+	}
+	return err;
+}
+
+static void
+vmci_transport_handle_wrote(struct sock *sk,
+			    struct vmci_transport_packet *pkt,
+			    bool bottom_half,
+			    struct sockaddr_vm *dst, struct sockaddr_vm *src)
+{
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	struct vsock_sock *vsk = vsock_sk(sk);
+	PKT_FIELD(vsk, sent_waiting_read) = false;
+#endif
+	vsock_data_ready(sk);
+}
+
+static void vmci_transport_notify_pkt_socket_init(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
+	PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
+	PKT_FIELD(vsk, peer_waiting_read) = false;
+	PKT_FIELD(vsk, peer_waiting_write) = false;
+	PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+	PKT_FIELD(vsk, sent_waiting_read) = false;
+	PKT_FIELD(vsk, sent_waiting_write) = false;
+	PKT_FIELD(vsk, produce_q_generation) = 0;
+	PKT_FIELD(vsk, consume_q_generation) = 0;
+
+	memset(&PKT_FIELD(vsk, peer_waiting_read_info), 0,
+	       sizeof(PKT_FIELD(vsk, peer_waiting_read_info)));
+	memset(&PKT_FIELD(vsk, peer_waiting_write_info), 0,
+	       sizeof(PKT_FIELD(vsk, peer_waiting_write_info)));
+}
+
+static void vmci_transport_notify_pkt_socket_destruct(struct vsock_sock *vsk)
+{
+}
+
+static int
+vmci_transport_notify_pkt_poll_in(struct sock *sk,
+				  size_t target, bool *data_ready_now)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (vsock_stream_has_data(vsk) >= target) {
+		*data_ready_now = true;
+	} else {
+		/* We can't read right now because there is not enough data
+		 * in the queue. Ask for notifications when there is something
+		 * to read.
+		 */
+		if (sk->sk_state == TCP_ESTABLISHED) {
+			if (!send_waiting_read(sk, 1))
+				return -1;
+
+		}
+		*data_ready_now = false;
+	}
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_poll_out(struct sock *sk,
+				   size_t target, bool *space_avail_now)
+{
+	s64 produce_q_free_space;
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	produce_q_free_space = vsock_stream_has_space(vsk);
+	if (produce_q_free_space > 0) {
+		*space_avail_now = true;
+		return 0;
+	} else if (produce_q_free_space == 0) {
+		/* This is a connected socket but we can't currently send data.
+		 * Notify the peer that we are waiting if the queue is full. We
+		 * only send a waiting write if the queue is full because
+		 * otherwise we end up in an infinite WAITING_WRITE, READ,
+		 * WAITING_WRITE, READ, etc. loop. Treat failing to send the
+		 * notification as a socket error, passing that back through
+		 * the mask.
+		 */
+		if (!send_waiting_write(sk, 1))
+			return -1;
+
+		*space_avail_now = false;
+	}
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_init(
+			struct sock *sk,
+			size_t target,
+			struct vmci_transport_recv_notify_data *data)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+#ifdef VSOCK_OPTIMIZATION_WAITING_NOTIFY
+	data->consume_head = 0;
+	data->produce_tail = 0;
+#ifdef VSOCK_OPTIMIZATION_FLOW_CONTROL
+	data->notify_on_block = false;
+
+	if (PKT_FIELD(vsk, write_notify_min_window) < target + 1) {
+		PKT_FIELD(vsk, write_notify_min_window) = target + 1;
+		if (PKT_FIELD(vsk, write_notify_window) <
+		    PKT_FIELD(vsk, write_notify_min_window)) {
+			/* If the current window is smaller than the new
+			 * minimal window size, we need to reevaluate whether
+			 * we need to notify the sender. If the number of ready
+			 * bytes are smaller than the new window, we need to
+			 * send a notification to the sender before we block.
+			 */
+
+			PKT_FIELD(vsk, write_notify_window) =
+			    PKT_FIELD(vsk, write_notify_min_window);
+			data->notify_on_block = true;
+		}
+	}
+#endif
+#endif
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_pre_block(
+				struct sock *sk,
+				size_t target,
+				struct vmci_transport_recv_notify_data *data)
+{
+	int err = 0;
+
+	/* Notify our peer that we are waiting for data to read. */
+	if (!send_waiting_read(sk, target)) {
+		err = -EHOSTUNREACH;
+		return err;
+	}
+#ifdef VSOCK_OPTIMIZATION_FLOW_CONTROL
+	if (data->notify_on_block) {
+		err = vmci_transport_send_read_notification(sk);
+		if (err < 0)
+			return err;
+
+		data->notify_on_block = false;
+	}
+#endif
+
+	return err;
+}
+
+static int
+vmci_transport_notify_pkt_recv_pre_dequeue(
+				struct sock *sk,
+				size_t target,
+				struct vmci_transport_recv_notify_data *data)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	/* Now consume up to len bytes from the queue.  Note that since we have
+	 * the socket locked we should copy at least ready bytes.
+	 */
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	vmci_qpair_get_consume_indexes(vmci_trans(vsk)->qpair,
+				       &data->produce_tail,
+				       &data->consume_head);
+#endif
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_post_dequeue(
+				struct sock *sk,
+				size_t target,
+				ssize_t copied,
+				bool data_read,
+				struct vmci_transport_recv_notify_data *data)
+{
+	struct vsock_sock *vsk;
+	int err;
+
+	vsk = vsock_sk(sk);
+	err = 0;
+
+	if (data_read) {
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+		/* Detect a wrap-around to maintain queue generation.  Note
+		 * that this is safe since we hold the socket lock across the
+		 * two queue pair operations.
+		 */
+		if (copied >=
+			vmci_trans(vsk)->consume_size - data->consume_head)
+			PKT_FIELD(vsk, consume_q_generation)++;
+#endif
+
+		err = vmci_transport_send_read_notification(sk);
+		if (err < 0)
+			return err;
+
+	}
+	return err;
+}
+
+static int
+vmci_transport_notify_pkt_send_init(
+			struct sock *sk,
+			struct vmci_transport_send_notify_data *data)
+{
+#ifdef VSOCK_OPTIMIZATION_WAITING_NOTIFY
+	data->consume_head = 0;
+	data->produce_tail = 0;
+#endif
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_send_pre_block(
+				struct sock *sk,
+				struct vmci_transport_send_notify_data *data)
+{
+	/* Notify our peer that we are waiting for room to write. */
+	if (!send_waiting_write(sk, 1))
+		return -EHOSTUNREACH;
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_send_pre_enqueue(
+				struct sock *sk,
+				struct vmci_transport_send_notify_data *data)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	vmci_qpair_get_produce_indexes(vmci_trans(vsk)->qpair,
+				       &data->produce_tail,
+				       &data->consume_head);
+#endif
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_send_post_enqueue(
+				struct sock *sk,
+				ssize_t written,
+				struct vmci_transport_send_notify_data *data)
+{
+	int err = 0;
+	struct vsock_sock *vsk;
+	bool sent_wrote = false;
+	int retries = 0;
+
+	vsk = vsock_sk(sk);
+
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+	/* Detect a wrap-around to maintain queue generation.  Note that this
+	 * is safe since we hold the socket lock across the two queue pair
+	 * operations.
+	 */
+	if (written >= vmci_trans(vsk)->produce_size - data->produce_tail)
+		PKT_FIELD(vsk, produce_q_generation)++;
+
+#endif
+
+	if (vmci_transport_notify_waiting_read(vsk)) {
+		/* Notify the peer that we have written, retrying the send on
+		 * failure up to our maximum value. See the XXX comment for the
+		 * corresponding piece of code in StreamRecvmsg() for potential
+		 * improvements.
+		 */
+		while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
+		       !sent_wrote &&
+		       retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+			err = vmci_transport_send_wrote(sk);
+			if (err >= 0)
+				sent_wrote = true;
+
+			retries++;
+		}
+
+		if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+			pr_err("%p unable to send wrote notify to peer\n", sk);
+			return err;
+		} else {
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+			PKT_FIELD(vsk, peer_waiting_read) = false;
+#endif
+		}
+	}
+	return err;
+}
+
+static void
+vmci_transport_notify_pkt_handle_pkt(
+			struct sock *sk,
+			struct vmci_transport_packet *pkt,
+			bool bottom_half,
+			struct sockaddr_vm *dst,
+			struct sockaddr_vm *src, bool *pkt_processed)
+{
+	bool processed = false;
+
+	switch (pkt->type) {
+	case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
+		vmci_transport_handle_wrote(sk, pkt, bottom_half, dst, src);
+		processed = true;
+		break;
+	case VMCI_TRANSPORT_PACKET_TYPE_READ:
+		vmci_transport_handle_read(sk, pkt, bottom_half, dst, src);
+		processed = true;
+		break;
+	case VMCI_TRANSPORT_PACKET_TYPE_WAITING_WRITE:
+		vmci_transport_handle_waiting_write(sk, pkt, bottom_half,
+						    dst, src);
+		processed = true;
+		break;
+
+	case VMCI_TRANSPORT_PACKET_TYPE_WAITING_READ:
+		vmci_transport_handle_waiting_read(sk, pkt, bottom_half,
+						   dst, src);
+		processed = true;
+		break;
+	}
+
+	if (pkt_processed)
+		*pkt_processed = processed;
+}
+
+static void vmci_transport_notify_pkt_process_request(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
+	if (vmci_trans(vsk)->consume_size <
+		PKT_FIELD(vsk, write_notify_min_window))
+		PKT_FIELD(vsk, write_notify_min_window) =
+			vmci_trans(vsk)->consume_size;
+}
+
+static void vmci_transport_notify_pkt_process_negotiate(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
+	if (vmci_trans(vsk)->consume_size <
+		PKT_FIELD(vsk, write_notify_min_window))
+		PKT_FIELD(vsk, write_notify_min_window) =
+			vmci_trans(vsk)->consume_size;
+}
+
+/* Socket control packet based operations. */
+const struct vmci_transport_notify_ops vmci_transport_notify_pkt_ops = {
+	.socket_init = vmci_transport_notify_pkt_socket_init,
+	.socket_destruct = vmci_transport_notify_pkt_socket_destruct,
+	.poll_in = vmci_transport_notify_pkt_poll_in,
+	.poll_out = vmci_transport_notify_pkt_poll_out,
+	.handle_notify_pkt = vmci_transport_notify_pkt_handle_pkt,
+	.recv_init = vmci_transport_notify_pkt_recv_init,
+	.recv_pre_block = vmci_transport_notify_pkt_recv_pre_block,
+	.recv_pre_dequeue = vmci_transport_notify_pkt_recv_pre_dequeue,
+	.recv_post_dequeue = vmci_transport_notify_pkt_recv_post_dequeue,
+	.send_init = vmci_transport_notify_pkt_send_init,
+	.send_pre_block = vmci_transport_notify_pkt_send_pre_block,
+	.send_pre_enqueue = vmci_transport_notify_pkt_send_pre_enqueue,
+	.send_post_enqueue = vmci_transport_notify_pkt_send_post_enqueue,
+	.process_request = vmci_transport_notify_pkt_process_request,
+	.process_negotiate = vmci_transport_notify_pkt_process_negotiate,
+};
diff --git a/net/vmw_vsock/vmci_transport_notify.h b/net/vmw_vsock/vmci_transport_notify.h
new file mode 100644
index 000000000..a1aa5a998
--- /dev/null
+++ b/net/vmw_vsock/vmci_transport_notify.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2009-2013 VMware, Inc. All rights reserved.
+ */
+
+#ifndef __VMCI_TRANSPORT_NOTIFY_H__
+#define __VMCI_TRANSPORT_NOTIFY_H__
+
+#include <linux/types.h>
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+
+#include "vmci_transport.h"
+
+/* Comment this out to compare with old protocol. */
+#define VSOCK_OPTIMIZATION_WAITING_NOTIFY 1
+#if defined(VSOCK_OPTIMIZATION_WAITING_NOTIFY)
+/* Comment this out to remove flow control for "new" protocol */
+#define VSOCK_OPTIMIZATION_FLOW_CONTROL 1
+#endif
+
+#define VMCI_TRANSPORT_MAX_DGRAM_RESENDS       10
+
+struct vmci_transport_recv_notify_data {
+	u64 consume_head;
+	u64 produce_tail;
+	bool notify_on_block;
+};
+
+struct vmci_transport_send_notify_data {
+	u64 consume_head;
+	u64 produce_tail;
+};
+
+/* Socket notification callbacks. */
+struct vmci_transport_notify_ops {
+	void (*socket_init) (struct sock *sk);
+	void (*socket_destruct) (struct vsock_sock *vsk);
+	int (*poll_in) (struct sock *sk, size_t target,
+			  bool *data_ready_now);
+	int (*poll_out) (struct sock *sk, size_t target,
+			   bool *space_avail_now);
+	void (*handle_notify_pkt) (struct sock *sk,
+				   struct vmci_transport_packet *pkt,
+				   bool bottom_half, struct sockaddr_vm *dst,
+				   struct sockaddr_vm *src,
+				   bool *pkt_processed);
+	int (*recv_init) (struct sock *sk, size_t target,
+			  struct vmci_transport_recv_notify_data *data);
+	int (*recv_pre_block) (struct sock *sk, size_t target,
+			       struct vmci_transport_recv_notify_data *data);
+	int (*recv_pre_dequeue) (struct sock *sk, size_t target,
+				 struct vmci_transport_recv_notify_data *data);
+	int (*recv_post_dequeue) (struct sock *sk, size_t target,
+				  ssize_t copied, bool data_read,
+				  struct vmci_transport_recv_notify_data *data);
+	int (*send_init) (struct sock *sk,
+			  struct vmci_transport_send_notify_data *data);
+	int (*send_pre_block) (struct sock *sk,
+			       struct vmci_transport_send_notify_data *data);
+	int (*send_pre_enqueue) (struct sock *sk,
+				 struct vmci_transport_send_notify_data *data);
+	int (*send_post_enqueue) (struct sock *sk, ssize_t written,
+				  struct vmci_transport_send_notify_data *data);
+	void (*process_request) (struct sock *sk);
+	void (*process_negotiate) (struct sock *sk);
+};
+
+extern const struct vmci_transport_notify_ops vmci_transport_notify_pkt_ops;
+extern const
+struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops;
+
+#endif /* __VMCI_TRANSPORT_NOTIFY_H__ */
diff --git a/net/vmw_vsock/vmci_transport_notify_qstate.c b/net/vmw_vsock/vmci_transport_notify_qstate.c
new file mode 100644
index 000000000..e96a88d85
--- /dev/null
+++ b/net/vmw_vsock/vmci_transport_notify_qstate.c
@@ -0,0 +1,430 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2009-2013 VMware, Inc. All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <net/sock.h>
+
+#include "vmci_transport_notify.h"
+
+#define PKT_FIELD(vsk, field_name) \
+	(vmci_trans(vsk)->notify.pkt_q_state.field_name)
+
+static bool vmci_transport_notify_waiting_write(struct vsock_sock *vsk)
+{
+	bool retval;
+	u64 notify_limit;
+
+	if (!PKT_FIELD(vsk, peer_waiting_write))
+		return false;
+
+	/* When the sender blocks, we take that as a sign that the sender is
+	 * faster than the receiver. To reduce the transmit rate of the sender,
+	 * we delay the sending of the read notification by decreasing the
+	 * write_notify_window. The notification is delayed until the number of
+	 * bytes used in the queue drops below the write_notify_window.
+	 */
+
+	if (!PKT_FIELD(vsk, peer_waiting_write_detected)) {
+		PKT_FIELD(vsk, peer_waiting_write_detected) = true;
+		if (PKT_FIELD(vsk, write_notify_window) < PAGE_SIZE) {
+			PKT_FIELD(vsk, write_notify_window) =
+			    PKT_FIELD(vsk, write_notify_min_window);
+		} else {
+			PKT_FIELD(vsk, write_notify_window) -= PAGE_SIZE;
+			if (PKT_FIELD(vsk, write_notify_window) <
+			    PKT_FIELD(vsk, write_notify_min_window))
+				PKT_FIELD(vsk, write_notify_window) =
+				    PKT_FIELD(vsk, write_notify_min_window);
+
+		}
+	}
+	notify_limit = vmci_trans(vsk)->consume_size -
+		PKT_FIELD(vsk, write_notify_window);
+
+	/* The notify_limit is used to delay notifications in the case where
+	 * flow control is enabled. Below the test is expressed in terms of
+	 * free space in the queue: if free_space > ConsumeSize -
+	 * write_notify_window then notify An alternate way of expressing this
+	 * is to rewrite the expression to use the data ready in the receive
+	 * queue: if write_notify_window > bufferReady then notify as
+	 * free_space == ConsumeSize - bufferReady.
+	 */
+
+	retval = vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair) >
+		notify_limit;
+
+	if (retval) {
+		/* Once we notify the peer, we reset the detected flag so the
+		 * next wait will again cause a decrease in the window size.
+		 */
+
+		PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+	}
+	return retval;
+}
+
+static void
+vmci_transport_handle_read(struct sock *sk,
+			   struct vmci_transport_packet *pkt,
+			   bool bottom_half,
+			   struct sockaddr_vm *dst, struct sockaddr_vm *src)
+{
+	sk->sk_write_space(sk);
+}
+
+static void
+vmci_transport_handle_wrote(struct sock *sk,
+			    struct vmci_transport_packet *pkt,
+			    bool bottom_half,
+			    struct sockaddr_vm *dst, struct sockaddr_vm *src)
+{
+	vsock_data_ready(sk);
+}
+
+static void vsock_block_update_write_window(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (PKT_FIELD(vsk, write_notify_window) < vmci_trans(vsk)->consume_size)
+		PKT_FIELD(vsk, write_notify_window) =
+		    min(PKT_FIELD(vsk, write_notify_window) + PAGE_SIZE,
+			vmci_trans(vsk)->consume_size);
+}
+
+static int vmci_transport_send_read_notification(struct sock *sk)
+{
+	struct vsock_sock *vsk;
+	bool sent_read;
+	unsigned int retries;
+	int err;
+
+	vsk = vsock_sk(sk);
+	sent_read = false;
+	retries = 0;
+	err = 0;
+
+	if (vmci_transport_notify_waiting_write(vsk)) {
+		/* Notify the peer that we have read, retrying the send on
+		 * failure up to our maximum value.  XXX For now we just log
+		 * the failure, but later we should schedule a work item to
+		 * handle the resend until it succeeds.  That would require
+		 * keeping track of work items in the vsk and cleaning them up
+		 * upon socket close.
+		 */
+		while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
+		       !sent_read &&
+		       retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+			err = vmci_transport_send_read(sk);
+			if (err >= 0)
+				sent_read = true;
+
+			retries++;
+		}
+
+		if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_read)
+			pr_err("%p unable to send read notification to peer\n",
+			       sk);
+		else
+			PKT_FIELD(vsk, peer_waiting_write) = false;
+
+	}
+	return err;
+}
+
+static void vmci_transport_notify_pkt_socket_init(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
+	PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
+	PKT_FIELD(vsk, peer_waiting_write) = false;
+	PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+}
+
+static void vmci_transport_notify_pkt_socket_destruct(struct vsock_sock *vsk)
+{
+	PKT_FIELD(vsk, write_notify_window) = PAGE_SIZE;
+	PKT_FIELD(vsk, write_notify_min_window) = PAGE_SIZE;
+	PKT_FIELD(vsk, peer_waiting_write) = false;
+	PKT_FIELD(vsk, peer_waiting_write_detected) = false;
+}
+
+static int
+vmci_transport_notify_pkt_poll_in(struct sock *sk,
+				  size_t target, bool *data_ready_now)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (vsock_stream_has_data(vsk) >= target) {
+		*data_ready_now = true;
+	} else {
+		/* We can't read right now because there is not enough data
+		 * in the queue. Ask for notifications when there is something
+		 * to read.
+		 */
+		if (sk->sk_state == TCP_ESTABLISHED)
+			vsock_block_update_write_window(sk);
+		*data_ready_now = false;
+	}
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_poll_out(struct sock *sk,
+				   size_t target, bool *space_avail_now)
+{
+	s64 produce_q_free_space;
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	produce_q_free_space = vsock_stream_has_space(vsk);
+	if (produce_q_free_space > 0) {
+		*space_avail_now = true;
+		return 0;
+	} else if (produce_q_free_space == 0) {
+		/* This is a connected socket but we can't currently send data.
+		 * Nothing else to do.
+		 */
+		*space_avail_now = false;
+	}
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_init(
+				struct sock *sk,
+				size_t target,
+				struct vmci_transport_recv_notify_data *data)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	data->consume_head = 0;
+	data->produce_tail = 0;
+	data->notify_on_block = false;
+
+	if (PKT_FIELD(vsk, write_notify_min_window) < target + 1) {
+		PKT_FIELD(vsk, write_notify_min_window) = target + 1;
+		if (PKT_FIELD(vsk, write_notify_window) <
+		    PKT_FIELD(vsk, write_notify_min_window)) {
+			/* If the current window is smaller than the new
+			 * minimal window size, we need to reevaluate whether
+			 * we need to notify the sender. If the number of ready
+			 * bytes are smaller than the new window, we need to
+			 * send a notification to the sender before we block.
+			 */
+
+			PKT_FIELD(vsk, write_notify_window) =
+			    PKT_FIELD(vsk, write_notify_min_window);
+			data->notify_on_block = true;
+		}
+	}
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_recv_pre_block(
+				struct sock *sk,
+				size_t target,
+				struct vmci_transport_recv_notify_data *data)
+{
+	int err = 0;
+
+	vsock_block_update_write_window(sk);
+
+	if (data->notify_on_block) {
+		err = vmci_transport_send_read_notification(sk);
+		if (err < 0)
+			return err;
+		data->notify_on_block = false;
+	}
+
+	return err;
+}
+
+static int
+vmci_transport_notify_pkt_recv_post_dequeue(
+				struct sock *sk,
+				size_t target,
+				ssize_t copied,
+				bool data_read,
+				struct vmci_transport_recv_notify_data *data)
+{
+	struct vsock_sock *vsk;
+	int err;
+	bool was_full = false;
+	u64 free_space;
+
+	vsk = vsock_sk(sk);
+	err = 0;
+
+	if (data_read) {
+		smp_mb();
+
+		free_space =
+			vmci_qpair_consume_free_space(vmci_trans(vsk)->qpair);
+		was_full = free_space == copied;
+
+		if (was_full)
+			PKT_FIELD(vsk, peer_waiting_write) = true;
+
+		err = vmci_transport_send_read_notification(sk);
+		if (err < 0)
+			return err;
+
+		/* See the comment in
+		 * vmci_transport_notify_pkt_send_post_enqueue().
+		 */
+		vsock_data_ready(sk);
+	}
+
+	return err;
+}
+
+static int
+vmci_transport_notify_pkt_send_init(
+				struct sock *sk,
+				struct vmci_transport_send_notify_data *data)
+{
+	data->consume_head = 0;
+	data->produce_tail = 0;
+
+	return 0;
+}
+
+static int
+vmci_transport_notify_pkt_send_post_enqueue(
+				struct sock *sk,
+				ssize_t written,
+				struct vmci_transport_send_notify_data *data)
+{
+	int err = 0;
+	struct vsock_sock *vsk;
+	bool sent_wrote = false;
+	bool was_empty;
+	int retries = 0;
+
+	vsk = vsock_sk(sk);
+
+	smp_mb();
+
+	was_empty =
+		vmci_qpair_produce_buf_ready(vmci_trans(vsk)->qpair) == written;
+	if (was_empty) {
+		while (!(vsk->peer_shutdown & RCV_SHUTDOWN) &&
+		       !sent_wrote &&
+		       retries < VMCI_TRANSPORT_MAX_DGRAM_RESENDS) {
+			err = vmci_transport_send_wrote(sk);
+			if (err >= 0)
+				sent_wrote = true;
+
+			retries++;
+		}
+	}
+
+	if (retries >= VMCI_TRANSPORT_MAX_DGRAM_RESENDS && !sent_wrote) {
+		pr_err("%p unable to send wrote notification to peer\n",
+		       sk);
+		return err;
+	}
+
+	return err;
+}
+
+static void
+vmci_transport_notify_pkt_handle_pkt(
+				struct sock *sk,
+				struct vmci_transport_packet *pkt,
+				bool bottom_half,
+				struct sockaddr_vm *dst,
+				struct sockaddr_vm *src, bool *pkt_processed)
+{
+	bool processed = false;
+
+	switch (pkt->type) {
+	case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
+		vmci_transport_handle_wrote(sk, pkt, bottom_half, dst, src);
+		processed = true;
+		break;
+	case VMCI_TRANSPORT_PACKET_TYPE_READ:
+		vmci_transport_handle_read(sk, pkt, bottom_half, dst, src);
+		processed = true;
+		break;
+	}
+
+	if (pkt_processed)
+		*pkt_processed = processed;
+}
+
+static void vmci_transport_notify_pkt_process_request(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
+	if (vmci_trans(vsk)->consume_size <
+		PKT_FIELD(vsk, write_notify_min_window))
+		PKT_FIELD(vsk, write_notify_min_window) =
+			vmci_trans(vsk)->consume_size;
+}
+
+static void vmci_transport_notify_pkt_process_negotiate(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	PKT_FIELD(vsk, write_notify_window) = vmci_trans(vsk)->consume_size;
+	if (vmci_trans(vsk)->consume_size <
+		PKT_FIELD(vsk, write_notify_min_window))
+		PKT_FIELD(vsk, write_notify_min_window) =
+			vmci_trans(vsk)->consume_size;
+}
+
+static int
+vmci_transport_notify_pkt_recv_pre_dequeue(
+				struct sock *sk,
+				size_t target,
+				struct vmci_transport_recv_notify_data *data)
+{
+	return 0; /* NOP for QState. */
+}
+
+static int
+vmci_transport_notify_pkt_send_pre_block(
+				struct sock *sk,
+				struct vmci_transport_send_notify_data *data)
+{
+	return 0; /* NOP for QState. */
+}
+
+static int
+vmci_transport_notify_pkt_send_pre_enqueue(
+				struct sock *sk,
+				struct vmci_transport_send_notify_data *data)
+{
+	return 0; /* NOP for QState. */
+}
+
+/* Socket always on control packet based operations. */
+const struct vmci_transport_notify_ops vmci_transport_notify_pkt_q_state_ops = {
+	.socket_init = vmci_transport_notify_pkt_socket_init,
+	.socket_destruct = vmci_transport_notify_pkt_socket_destruct,
+	.poll_in = vmci_transport_notify_pkt_poll_in,
+	.poll_out = vmci_transport_notify_pkt_poll_out,
+	.handle_notify_pkt = vmci_transport_notify_pkt_handle_pkt,
+	.recv_init = vmci_transport_notify_pkt_recv_init,
+	.recv_pre_block = vmci_transport_notify_pkt_recv_pre_block,
+	.recv_pre_dequeue = vmci_transport_notify_pkt_recv_pre_dequeue,
+	.recv_post_dequeue = vmci_transport_notify_pkt_recv_post_dequeue,
+	.send_init = vmci_transport_notify_pkt_send_init,
+	.send_pre_block = vmci_transport_notify_pkt_send_pre_block,
+	.send_pre_enqueue = vmci_transport_notify_pkt_send_pre_enqueue,
+	.send_post_enqueue = vmci_transport_notify_pkt_send_post_enqueue,
+	.process_request = vmci_transport_notify_pkt_process_request,
+	.process_negotiate = vmci_transport_notify_pkt_process_negotiate,
+};
diff --git a/net/vmw_vsock/vsock_addr.c b/net/vmw_vsock/vsock_addr.c
new file mode 100644
index 000000000..a986aa6ff
--- /dev/null
+++ b/net/vmw_vsock/vsock_addr.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMware vSockets Driver
+ *
+ * Copyright (C) 2007-2012 VMware, Inc. All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <net/sock.h>
+#include <net/vsock_addr.h>
+
+void vsock_addr_init(struct sockaddr_vm *addr, u32 cid, u32 port)
+{
+	memset(addr, 0, sizeof(*addr));
+	addr->svm_family = AF_VSOCK;
+	addr->svm_cid = cid;
+	addr->svm_port = port;
+}
+EXPORT_SYMBOL_GPL(vsock_addr_init);
+
+int vsock_addr_validate(const struct sockaddr_vm *addr)
+{
+	__u8 svm_valid_flags = VMADDR_FLAG_TO_HOST;
+
+	if (!addr)
+		return -EFAULT;
+
+	if (addr->svm_family != AF_VSOCK)
+		return -EAFNOSUPPORT;
+
+	if (addr->svm_flags & ~svm_valid_flags)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vsock_addr_validate);
+
+bool vsock_addr_bound(const struct sockaddr_vm *addr)
+{
+	return addr->svm_port != VMADDR_PORT_ANY;
+}
+EXPORT_SYMBOL_GPL(vsock_addr_bound);
+
+void vsock_addr_unbind(struct sockaddr_vm *addr)
+{
+	vsock_addr_init(addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
+}
+EXPORT_SYMBOL_GPL(vsock_addr_unbind);
+
+bool vsock_addr_equals_addr(const struct sockaddr_vm *addr,
+			    const struct sockaddr_vm *other)
+{
+	return addr->svm_cid == other->svm_cid &&
+		addr->svm_port == other->svm_port;
+}
+EXPORT_SYMBOL_GPL(vsock_addr_equals_addr);
+
+int vsock_addr_cast(const struct sockaddr_unsized *addr,
+		    size_t len, struct sockaddr_vm **out_addr)
+{
+	if (len < sizeof(**out_addr))
+		return -EFAULT;
+
+	*out_addr = (struct sockaddr_vm *)addr;
+	return vsock_addr_validate(*out_addr);
+}
+EXPORT_SYMBOL_GPL(vsock_addr_cast);
diff --git a/net/vmw_vsock/vsock_bpf.c b/net/vmw_vsock/vsock_bpf.c
new file mode 100644
index 000000000..9049d2648
--- /dev/null
+++ b/net/vmw_vsock/vsock_bpf.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Bobby Eshleman <bobby.eshleman@bytedance.com>
+ *
+ * Based off of net/unix/unix_bpf.c
+ */
+
+#include <linux/bpf.h>
+#include <linux/module.h>
+#include <linux/skmsg.h>
+#include <linux/socket.h>
+#include <linux/wait.h>
+#include <net/af_vsock.h>
+#include <net/sock.h>
+
+#define vsock_sk_has_data(__sk, __psock)				\
+		({	!skb_queue_empty(&(__sk)->sk_receive_queue) ||	\
+			!skb_queue_empty(&(__psock)->ingress_skb) ||	\
+			!list_empty(&(__psock)->ingress_msg);		\
+		})
+
+static struct proto *vsock_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(vsock_prot_lock);
+static struct proto vsock_bpf_prot;
+
+static bool vsock_has_data(struct sock *sk, struct sk_psock *psock)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+	s64 ret;
+
+	ret = vsock_connectible_has_data(vsk);
+	if (ret > 0)
+		return true;
+
+	return vsock_sk_has_data(sk, psock);
+}
+
+static bool vsock_msg_wait_data(struct sock *sk, struct sk_psock *psock, long timeo)
+{
+	bool ret;
+
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		return true;
+
+	if (!timeo)
+		return false;
+
+	add_wait_queue(sk_sleep(sk), &wait);
+	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	ret = vsock_has_data(sk, psock);
+	if (!ret) {
+		wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+		ret = vsock_has_data(sk, psock);
+	}
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	return ret;
+}
+
+static int __vsock_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags)
+{
+	struct socket *sock = sk->sk_socket;
+	int err;
+
+	if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
+		err = __vsock_connectible_recvmsg(sock, msg, len, flags);
+	else if (sk->sk_type == SOCK_DGRAM)
+		err = __vsock_dgram_recvmsg(sock, msg, len, flags);
+	else
+		err = -EPROTOTYPE;
+
+	return err;
+}
+
+static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
+			     size_t len, int flags)
+{
+	struct sk_psock *psock;
+	struct vsock_sock *vsk;
+	int copied;
+
+	psock = sk_psock_get(sk);
+	if (unlikely(!psock))
+		return __vsock_recvmsg(sk, msg, len, flags);
+
+	lock_sock(sk);
+	vsk = vsock_sk(sk);
+
+	if (WARN_ON_ONCE(!vsk->transport)) {
+		copied = -ENODEV;
+		goto out;
+	}
+
+	if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) {
+		release_sock(sk);
+		sk_psock_put(sk, psock);
+		return __vsock_recvmsg(sk, msg, len, flags);
+	}
+
+	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
+	while (copied == 0) {
+		long timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+
+		if (!vsock_msg_wait_data(sk, psock, timeo)) {
+			copied = -EAGAIN;
+			break;
+		}
+
+		if (sk_psock_queue_empty(psock)) {
+			release_sock(sk);
+			sk_psock_put(sk, psock);
+			return __vsock_recvmsg(sk, msg, len, flags);
+		}
+
+		copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
+	}
+
+out:
+	release_sock(sk);
+	sk_psock_put(sk, psock);
+
+	return copied;
+}
+
+static void vsock_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
+{
+	*prot        = *base;
+	prot->close  = sock_map_close;
+	prot->recvmsg = vsock_bpf_recvmsg;
+	prot->sock_is_readable = sk_msg_is_readable;
+}
+
+static void vsock_bpf_check_needs_rebuild(struct proto *ops)
+{
+	/* Paired with the smp_store_release() below. */
+	if (unlikely(ops != smp_load_acquire(&vsock_prot_saved))) {
+		spin_lock_bh(&vsock_prot_lock);
+		if (likely(ops != vsock_prot_saved)) {
+			vsock_bpf_rebuild_protos(&vsock_bpf_prot, ops);
+			/* Make sure proto function pointers are updated before publishing the
+			 * pointer to the struct.
+			 */
+			smp_store_release(&vsock_prot_saved, ops);
+		}
+		spin_unlock_bh(&vsock_prot_lock);
+	}
+}
+
+int vsock_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+	struct vsock_sock *vsk;
+
+	if (restore) {
+		sk->sk_write_space = psock->saved_write_space;
+		sock_replace_proto(sk, psock->sk_proto);
+		return 0;
+	}
+
+	vsk = vsock_sk(sk);
+	if (!vsk->transport)
+		return -ENODEV;
+
+	if (!vsk->transport->read_skb)
+		return -EOPNOTSUPP;
+
+	vsock_bpf_check_needs_rebuild(psock->sk_proto);
+	sock_replace_proto(sk, &vsock_bpf_prot);
+	return 0;
+}
+
+void __init vsock_bpf_build_proto(void)
+{
+	vsock_bpf_rebuild_protos(&vsock_bpf_prot, &vsock_proto);
+}
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
new file mode 100644
index 000000000..8068d1b6e
--- /dev/null
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* loopback transport for vsock using virtio_transport_common APIs
+ *
+ * Copyright (C) 2013-2019 Red Hat, Inc.
+ * Authors: Asias He <asias@redhat.com>
+ *          Stefan Hajnoczi <stefanha@redhat.com>
+ *          Stefano Garzarella <sgarzare@redhat.com>
+ *
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/virtio_vsock.h>
+
+struct vsock_loopback {
+	struct workqueue_struct *workqueue;
+
+	struct sk_buff_head pkt_queue;
+	struct work_struct pkt_work;
+};
+
+static struct vsock_loopback the_vsock_loopback;
+
+static u32 vsock_loopback_get_local_cid(void)
+{
+	return VMADDR_CID_LOCAL;
+}
+
+static int vsock_loopback_send_pkt(struct sk_buff *skb, struct net *net)
+{
+	struct vsock_loopback *vsock = &the_vsock_loopback;
+	int len = skb->len;
+
+	virtio_vsock_skb_queue_tail(&vsock->pkt_queue, skb);
+	queue_work(vsock->workqueue, &vsock->pkt_work);
+
+	return len;
+}
+
+static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
+{
+	struct vsock_loopback *vsock = &the_vsock_loopback;
+
+	virtio_transport_purge_skbs(vsk, &vsock->pkt_queue);
+
+	return 0;
+}
+
+static bool vsock_loopback_seqpacket_allow(struct vsock_sock *vsk,
+					   u32 remote_cid);
+
+static bool vsock_loopback_stream_allow(struct vsock_sock *vsk, u32 cid,
+					u32 port)
+{
+	return true;
+}
+
+static bool vsock_loopback_msgzerocopy_allow(void)
+{
+	return true;
+}
+
+static struct virtio_transport loopback_transport = {
+	.transport = {
+		.module                   = THIS_MODULE,
+
+		.get_local_cid            = vsock_loopback_get_local_cid,
+
+		.init                     = virtio_transport_do_socket_init,
+		.destruct                 = virtio_transport_destruct,
+		.release                  = virtio_transport_release,
+		.connect                  = virtio_transport_connect,
+		.shutdown                 = virtio_transport_shutdown,
+		.cancel_pkt               = vsock_loopback_cancel_pkt,
+
+		.dgram_bind               = virtio_transport_dgram_bind,
+		.dgram_dequeue            = virtio_transport_dgram_dequeue,
+		.dgram_enqueue            = virtio_transport_dgram_enqueue,
+		.dgram_allow              = virtio_transport_dgram_allow,
+
+		.stream_dequeue           = virtio_transport_stream_dequeue,
+		.stream_enqueue           = virtio_transport_stream_enqueue,
+		.stream_has_data          = virtio_transport_stream_has_data,
+		.stream_has_space         = virtio_transport_stream_has_space,
+		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
+		.stream_is_active         = virtio_transport_stream_is_active,
+		.stream_allow             = vsock_loopback_stream_allow,
+
+		.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
+		.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
+		.seqpacket_allow          = vsock_loopback_seqpacket_allow,
+		.seqpacket_has_data       = virtio_transport_seqpacket_has_data,
+
+		.msgzerocopy_allow        = vsock_loopback_msgzerocopy_allow,
+
+		.notify_poll_in           = virtio_transport_notify_poll_in,
+		.notify_poll_out          = virtio_transport_notify_poll_out,
+		.notify_recv_init         = virtio_transport_notify_recv_init,
+		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
+		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
+		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
+		.notify_send_init         = virtio_transport_notify_send_init,
+		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
+		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
+		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
+		.notify_buffer_size       = virtio_transport_notify_buffer_size,
+		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
+
+		.unsent_bytes             = virtio_transport_unsent_bytes,
+
+		.read_skb = virtio_transport_read_skb,
+	},
+
+	.send_pkt = vsock_loopback_send_pkt,
+};
+
+static bool
+vsock_loopback_seqpacket_allow(struct vsock_sock *vsk, u32 remote_cid)
+{
+	return vsock_net_mode_global(vsk);
+}
+
+static void vsock_loopback_work(struct work_struct *work)
+{
+	struct vsock_loopback *vsock =
+		container_of(work, struct vsock_loopback, pkt_work);
+	struct sk_buff_head pkts;
+	struct sk_buff *skb;
+
+	skb_queue_head_init(&pkts);
+
+	spin_lock_bh(&vsock->pkt_queue.lock);
+	skb_queue_splice_init(&vsock->pkt_queue, &pkts);
+	spin_unlock_bh(&vsock->pkt_queue.lock);
+
+	while ((skb = __skb_dequeue(&pkts))) {
+		/* Decrement the bytes_unsent counter without deallocating skb
+		 * It is freed by the receiver.
+		 */
+		virtio_transport_consume_skb_sent(skb, false);
+		virtio_transport_deliver_tap_pkt(skb);
+		virtio_transport_recv_pkt(&loopback_transport, skb,
+					  sock_net(skb->sk));
+	}
+}
+
+static int __init vsock_loopback_init(void)
+{
+	struct vsock_loopback *vsock = &the_vsock_loopback;
+	int ret;
+
+	vsock->workqueue = alloc_workqueue("vsock-loopback", WQ_PERCPU, 0);
+	if (!vsock->workqueue)
+		return -ENOMEM;
+
+	skb_queue_head_init(&vsock->pkt_queue);
+	INIT_WORK(&vsock->pkt_work, vsock_loopback_work);
+
+	ret = vsock_core_register(&loopback_transport.transport,
+				  VSOCK_TRANSPORT_F_LOCAL);
+	if (ret)
+		goto out_wq;
+
+	return 0;
+
+out_wq:
+	destroy_workqueue(vsock->workqueue);
+	return ret;
+}
+
+static void __exit vsock_loopback_exit(void)
+{
+	struct vsock_loopback *vsock = &the_vsock_loopback;
+
+	vsock_core_unregister(&loopback_transport.transport);
+
+	flush_work(&vsock->pkt_work);
+
+	virtio_vsock_skb_queue_purge(&vsock->pkt_queue);
+
+	destroy_workqueue(vsock->workqueue);
+}
+
+module_init(vsock_loopback_init);
+module_exit(vsock_loopback_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Stefano Garzarella <sgarzare@redhat.com>");
+MODULE_DESCRIPTION("loopback transport for vsock");
+MODULE_ALIAS_NETPROTO(PF_VSOCK);