Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

12 files changed, 12588 insertions, 0 deletions

diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
new file mode 100644
index 000000000..b455d9ab6
--- /dev/null
+++ b/drivers/vhost/Kconfig
@@ -0,0 +1,97 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config VHOST_IOTLB
+	tristate
+	help
+	  Generic IOTLB implementation for vhost and vringh.
+	  This option is selected by any driver which needs to support
+	  an IOMMU in software.
+
+config VHOST_RING
+	tristate
+	select VHOST_IOTLB
+	help
+	  This option is selected by any driver which needs to access
+	  the host side of a virtio ring.
+
+config VHOST_TASK
+	bool
+	default n
+
+config VHOST
+	tristate
+	select VHOST_IOTLB
+	select VHOST_TASK
+	help
+	  This option is selected by any driver which needs to access
+	  the core of vhost.
+
+menuconfig VHOST_MENU
+	bool "VHOST drivers"
+	default y
+
+if VHOST_MENU
+
+config VHOST_NET
+	tristate "Host kernel accelerator for virtio net"
+	depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP)
+	select VHOST
+	help
+	  This kernel module can be loaded in host kernel to accelerate
+	  guest networking with virtio_net. Not to be confused with virtio_net
+	  module itself which needs to be loaded in guest kernel.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called vhost_net.
+
+config VHOST_SCSI
+	tristate "VHOST_SCSI TCM fabric driver"
+	depends on TARGET_CORE && EVENTFD
+	select VHOST
+	default n
+	help
+	Say M here to enable the vhost_scsi TCM fabric module
+	for use with virtio-scsi guests
+
+config VHOST_VSOCK
+	tristate "vhost virtio-vsock driver"
+	depends on VSOCKETS && EVENTFD
+	select VHOST
+	select VIRTIO_VSOCKETS_COMMON
+	default n
+	help
+	This kernel module can be loaded in the host kernel to provide AF_VSOCK
+	sockets for communicating with guests.  The guests must have the
+	virtio_transport.ko driver loaded to use the virtio-vsock device.
+
+	To compile this driver as a module, choose M here: the module will be called
+	vhost_vsock.
+
+config VHOST_VDPA
+	tristate "Vhost driver for vDPA-based backend"
+	depends on EVENTFD
+	select VHOST
+	select IRQ_BYPASS_MANAGER
+	depends on VDPA
+	help
+	  This kernel module can be loaded in host kernel to accelerate
+	  guest virtio devices with the vDPA-based backends.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called vhost_vdpa.
+
+config VHOST_CROSS_ENDIAN_LEGACY
+	bool "Cross-endian support for vhost"
+	default n
+	help
+	  This option allows vhost to support guests with a different byte
+	  ordering from host while using legacy virtio.
+
+	  Userspace programs can control the feature using the
+	  VHOST_SET_VRING_ENDIAN and VHOST_GET_VRING_ENDIAN ioctls.
+
+	  This is only useful on a few platforms (ppc64 and arm64). Since it
+	  adds some overhead, it is disabled by default.
+
+	  If unsure, say "N".
+
+endif
diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
new file mode 100644
index 000000000..f3e1897cc
--- /dev/null
+++ b/drivers/vhost/Makefile
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_VHOST_NET) += vhost_net.o
+vhost_net-y := net.o
+
+obj-$(CONFIG_VHOST_SCSI) += vhost_scsi.o
+vhost_scsi-y := scsi.o
+
+obj-$(CONFIG_VHOST_VSOCK) += vhost_vsock.o
+vhost_vsock-y := vsock.o
+
+obj-$(CONFIG_VHOST_RING) += vringh.o
+
+obj-$(CONFIG_VHOST_VDPA) += vhost_vdpa.o
+vhost_vdpa-y := vdpa.o
+
+obj-$(CONFIG_VHOST)	+= vhost.o
+
+obj-$(CONFIG_VHOST_IOTLB) += vhost_iotlb.o
+vhost_iotlb-y := iotlb.o
diff --git a/drivers/vhost/iotlb.c b/drivers/vhost/iotlb.c
new file mode 100644
index 000000000..ea61330a3
--- /dev/null
+++ b/drivers/vhost/iotlb.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2020 Red Hat, Inc.
+ * Author: Jason Wang <jasowang@redhat.com>
+ *
+ * IOTLB implementation for vhost.
+ */
+#include <linux/slab.h>
+#include <linux/vhost_iotlb.h>
+#include <linux/module.h>
+
+#define MOD_VERSION  "0.1"
+#define MOD_DESC     "VHOST IOTLB"
+#define MOD_AUTHOR   "Jason Wang <jasowang@redhat.com>"
+#define MOD_LICENSE  "GPL v2"
+
+#define START(map) ((map)->start)
+#define LAST(map) ((map)->last)
+
+INTERVAL_TREE_DEFINE(struct vhost_iotlb_map,
+		     rb, __u64, __subtree_last,
+		     START, LAST, static inline, vhost_iotlb_itree);
+
+/**
+ * vhost_iotlb_map_free - remove a map node and free it
+ * @iotlb: the IOTLB
+ * @map: the map that want to be remove and freed
+ */
+void vhost_iotlb_map_free(struct vhost_iotlb *iotlb,
+			  struct vhost_iotlb_map *map)
+{
+	vhost_iotlb_itree_remove(map, &iotlb->root);
+	list_del(&map->link);
+	kfree(map);
+	iotlb->nmaps--;
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_map_free);
+
+/**
+ * vhost_iotlb_add_range_ctx - add a new range to vhost IOTLB
+ * @iotlb: the IOTLB
+ * @start: start of the IOVA range
+ * @last: last of IOVA range
+ * @addr: the address that is mapped to @start
+ * @perm: access permission of this range
+ * @opaque: the opaque pointer for the new mapping
+ *
+ * Returns an error last is smaller than start or memory allocation
+ * fails
+ */
+int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb,
+			      u64 start, u64 last,
+			      u64 addr, unsigned int perm,
+			      void *opaque)
+{
+	struct vhost_iotlb_map *map;
+
+	if (last < start)
+		return -EFAULT;
+
+	/* If the range being mapped is [0, ULONG_MAX], split it into two entries
+	 * otherwise its size would overflow u64.
+	 */
+	if (start == 0 && last == ULONG_MAX) {
+		u64 mid = last / 2;
+		int err = vhost_iotlb_add_range_ctx(iotlb, start, mid, addr,
+				perm, opaque);
+
+		if (err)
+			return err;
+
+		addr += mid + 1;
+		start = mid + 1;
+	}
+
+	if (iotlb->limit &&
+	    iotlb->nmaps == iotlb->limit &&
+	    iotlb->flags & VHOST_IOTLB_FLAG_RETIRE) {
+		map = list_first_entry(&iotlb->list, typeof(*map), link);
+		vhost_iotlb_map_free(iotlb, map);
+	}
+
+	map = kmalloc(sizeof(*map), GFP_ATOMIC);
+	if (!map)
+		return -ENOMEM;
+
+	map->start = start;
+	map->size = last - start + 1;
+	map->last = last;
+	map->addr = addr;
+	map->perm = perm;
+	map->opaque = opaque;
+
+	iotlb->nmaps++;
+	vhost_iotlb_itree_insert(map, &iotlb->root);
+
+	INIT_LIST_HEAD(&map->link);
+	list_add_tail(&map->link, &iotlb->list);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_add_range_ctx);
+
+int vhost_iotlb_add_range(struct vhost_iotlb *iotlb,
+			  u64 start, u64 last,
+			  u64 addr, unsigned int perm)
+{
+	return vhost_iotlb_add_range_ctx(iotlb, start, last,
+					 addr, perm, NULL);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_add_range);
+
+/**
+ * vhost_iotlb_del_range - delete overlapped ranges from vhost IOTLB
+ * @iotlb: the IOTLB
+ * @start: start of the IOVA range
+ * @last: last of IOVA range
+ */
+void vhost_iotlb_del_range(struct vhost_iotlb *iotlb, u64 start, u64 last)
+{
+	struct vhost_iotlb_map *map;
+
+	while ((map = vhost_iotlb_itree_iter_first(&iotlb->root,
+						   start, last)))
+		vhost_iotlb_map_free(iotlb, map);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_del_range);
+
+/**
+ * vhost_iotlb_init - initialize a vhost IOTLB
+ * @iotlb: the IOTLB that needs to be initialized
+ * @limit: maximum number of IOTLB entries
+ * @flags: VHOST_IOTLB_FLAG_XXX
+ */
+void vhost_iotlb_init(struct vhost_iotlb *iotlb, unsigned int limit,
+		      unsigned int flags)
+{
+	iotlb->root = RB_ROOT_CACHED;
+	iotlb->limit = limit;
+	iotlb->nmaps = 0;
+	iotlb->flags = flags;
+	INIT_LIST_HEAD(&iotlb->list);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_init);
+
+/**
+ * vhost_iotlb_alloc - add a new vhost IOTLB
+ * @limit: maximum number of IOTLB entries
+ * @flags: VHOST_IOTLB_FLAG_XXX
+ *
+ * Returns an error is memory allocation fails
+ */
+struct vhost_iotlb *vhost_iotlb_alloc(unsigned int limit, unsigned int flags)
+{
+	struct vhost_iotlb *iotlb = kzalloc(sizeof(*iotlb), GFP_KERNEL);
+
+	if (!iotlb)
+		return NULL;
+
+	vhost_iotlb_init(iotlb, limit, flags);
+
+	return iotlb;
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_alloc);
+
+/**
+ * vhost_iotlb_reset - reset vhost IOTLB (free all IOTLB entries)
+ * @iotlb: the IOTLB to be reset
+ */
+void vhost_iotlb_reset(struct vhost_iotlb *iotlb)
+{
+	vhost_iotlb_del_range(iotlb, 0ULL, 0ULL - 1);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_reset);
+
+/**
+ * vhost_iotlb_free - reset and free vhost IOTLB
+ * @iotlb: the IOTLB to be freed
+ */
+void vhost_iotlb_free(struct vhost_iotlb *iotlb)
+{
+	if (iotlb) {
+		vhost_iotlb_reset(iotlb);
+		kfree(iotlb);
+	}
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_free);
+
+/**
+ * vhost_iotlb_itree_first - return the first overlapped range
+ * @iotlb: the IOTLB
+ * @start: start of IOVA range
+ * @last: last byte in IOVA range
+ */
+struct vhost_iotlb_map *
+vhost_iotlb_itree_first(struct vhost_iotlb *iotlb, u64 start, u64 last)
+{
+	return vhost_iotlb_itree_iter_first(&iotlb->root, start, last);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_itree_first);
+
+/**
+ * vhost_iotlb_itree_next - return the next overlapped range
+ * @map: the starting map node
+ * @start: start of IOVA range
+ * @last: last byte IOVA range
+ */
+struct vhost_iotlb_map *
+vhost_iotlb_itree_next(struct vhost_iotlb_map *map, u64 start, u64 last)
+{
+	return vhost_iotlb_itree_iter_next(map, start, last);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_itree_next);
+
+MODULE_VERSION(MOD_VERSION);
+MODULE_DESCRIPTION(MOD_DESC);
+MODULE_AUTHOR(MOD_AUTHOR);
+MODULE_LICENSE(MOD_LICENSE);
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
new file mode 100644
index 000000000..f2ed7167c
--- /dev/null
+++ b/drivers/vhost/net.c
@@ -0,0 +1,1815 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2009 Red Hat, Inc.
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ * virtio-net server in host kernel.
+ */
+
+#include <linux/compat.h>
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/virtio_net.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/sched/clock.h>
+#include <linux/sched/signal.h>
+#include <linux/vmalloc.h>
+
+#include <linux/net.h>
+#include <linux/if_packet.h>
+#include <linux/if_arp.h>
+#include <linux/if_tun.h>
+#include <linux/if_macvlan.h>
+#include <linux/if_tap.h>
+#include <linux/if_vlan.h>
+#include <linux/skb_array.h>
+#include <linux/skbuff.h>
+
+#include <net/sock.h>
+#include <net/xdp.h>
+
+#include "vhost.h"
+
+static int experimental_zcopytx = 0;
+module_param(experimental_zcopytx, int, 0444);
+MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
+		                       " 1 -Enable; 0 - Disable");
+
+/* Max number of bytes transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others. */
+#define VHOST_NET_WEIGHT 0x80000
+
+/* Max number of packets transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others with small
+ * pkts.
+ */
+#define VHOST_NET_PKT_WEIGHT 256
+
+/* MAX number of TX used buffers for outstanding zerocopy */
+#define VHOST_MAX_PEND 128
+#define VHOST_GOODCOPY_LEN 256
+
+/*
+ * For transmit, used buffer len is unused; we override it to track buffer
+ * status internally; used for zerocopy tx only.
+ */
+/* Lower device DMA failed */
+#define VHOST_DMA_FAILED_LEN	((__force __virtio32)3)
+/* Lower device DMA done */
+#define VHOST_DMA_DONE_LEN	((__force __virtio32)2)
+/* Lower device DMA in progress */
+#define VHOST_DMA_IN_PROGRESS	((__force __virtio32)1)
+/* Buffer unused */
+#define VHOST_DMA_CLEAR_LEN	((__force __virtio32)0)
+
+#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
+
+enum {
+	VHOST_NET_FEATURES = VHOST_FEATURES |
+			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
+			 (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+			 (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
+			 (1ULL << VIRTIO_F_RING_RESET)
+};
+
+enum {
+	VHOST_NET_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
+};
+
+enum {
+	VHOST_NET_VQ_RX = 0,
+	VHOST_NET_VQ_TX = 1,
+	VHOST_NET_VQ_MAX = 2,
+};
+
+struct vhost_net_ubuf_ref {
+	/* refcount follows semantics similar to kref:
+	 *  0: object is released
+	 *  1: no outstanding ubufs
+	 * >1: outstanding ubufs
+	 */
+	atomic_t refcount;
+	wait_queue_head_t wait;
+	struct vhost_virtqueue *vq;
+};
+
+#define VHOST_NET_BATCH 64
+struct vhost_net_buf {
+	void **queue;
+	int tail;
+	int head;
+};
+
+struct vhost_net_virtqueue {
+	struct vhost_virtqueue vq;
+	size_t vhost_hlen;
+	size_t sock_hlen;
+	/* vhost zerocopy support fields below: */
+	/* last used idx for outstanding DMA zerocopy buffers */
+	int upend_idx;
+	/* For TX, first used idx for DMA done zerocopy buffers
+	 * For RX, number of batched heads
+	 */
+	int done_idx;
+	/* Number of XDP frames batched */
+	int batched_xdp;
+	/* an array of userspace buffers info */
+	struct ubuf_info_msgzc *ubuf_info;
+	/* Reference counting for outstanding ubufs.
+	 * Protected by vq mutex. Writers must also take device mutex. */
+	struct vhost_net_ubuf_ref *ubufs;
+	struct ptr_ring *rx_ring;
+	struct vhost_net_buf rxq;
+	/* Batched XDP buffs */
+	struct xdp_buff *xdp;
+};
+
+struct vhost_net {
+	struct vhost_dev dev;
+	struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
+	struct vhost_poll poll[VHOST_NET_VQ_MAX];
+	/* Number of TX recently submitted.
+	 * Protected by tx vq lock. */
+	unsigned tx_packets;
+	/* Number of times zerocopy TX recently failed.
+	 * Protected by tx vq lock. */
+	unsigned tx_zcopy_err;
+	/* Flush in progress. Protected by tx vq lock. */
+	bool tx_flush;
+	/* Private page frag */
+	struct page_frag page_frag;
+	/* Refcount bias of page frag */
+	int refcnt_bias;
+};
+
+static unsigned vhost_net_zcopy_mask __read_mostly;
+
+static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
+{
+	if (rxq->tail != rxq->head)
+		return rxq->queue[rxq->head];
+	else
+		return NULL;
+}
+
+static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
+{
+	return rxq->tail - rxq->head;
+}
+
+static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
+{
+	return rxq->tail == rxq->head;
+}
+
+static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
+{
+	void *ret = vhost_net_buf_get_ptr(rxq);
+	++rxq->head;
+	return ret;
+}
+
+static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
+{
+	struct vhost_net_buf *rxq = &nvq->rxq;
+
+	rxq->head = 0;
+	rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
+					      VHOST_NET_BATCH);
+	return rxq->tail;
+}
+
+static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
+{
+	struct vhost_net_buf *rxq = &nvq->rxq;
+
+	if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
+		ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
+				   vhost_net_buf_get_size(rxq),
+				   tun_ptr_free);
+		rxq->head = rxq->tail = 0;
+	}
+}
+
+static int vhost_net_buf_peek_len(void *ptr)
+{
+	if (tun_is_xdp_frame(ptr)) {
+		struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
+
+		return xdpf->len;
+	}
+
+	return __skb_array_len_with_tag(ptr);
+}
+
+static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
+{
+	struct vhost_net_buf *rxq = &nvq->rxq;
+
+	if (!vhost_net_buf_is_empty(rxq))
+		goto out;
+
+	if (!vhost_net_buf_produce(nvq))
+		return 0;
+
+out:
+	return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
+}
+
+static void vhost_net_buf_init(struct vhost_net_buf *rxq)
+{
+	rxq->head = rxq->tail = 0;
+}
+
+static void vhost_net_enable_zcopy(int vq)
+{
+	vhost_net_zcopy_mask |= 0x1 << vq;
+}
+
+static struct vhost_net_ubuf_ref *
+vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
+{
+	struct vhost_net_ubuf_ref *ubufs;
+	/* No zero copy backend? Nothing to count. */
+	if (!zcopy)
+		return NULL;
+	ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
+	if (!ubufs)
+		return ERR_PTR(-ENOMEM);
+	atomic_set(&ubufs->refcount, 1);
+	init_waitqueue_head(&ubufs->wait);
+	ubufs->vq = vq;
+	return ubufs;
+}
+
+static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
+{
+	int r = atomic_sub_return(1, &ubufs->refcount);
+	if (unlikely(!r))
+		wake_up(&ubufs->wait);
+	return r;
+}
+
+static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
+{
+	vhost_net_ubuf_put(ubufs);
+	wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
+}
+
+static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
+{
+	vhost_net_ubuf_put_and_wait(ubufs);
+	kfree(ubufs);
+}
+
+static void vhost_net_clear_ubuf_info(struct vhost_net *n)
+{
+	int i;
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		kfree(n->vqs[i].ubuf_info);
+		n->vqs[i].ubuf_info = NULL;
+	}
+}
+
+static int vhost_net_set_ubuf_info(struct vhost_net *n)
+{
+	bool zcopy;
+	int i;
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		zcopy = vhost_net_zcopy_mask & (0x1 << i);
+		if (!zcopy)
+			continue;
+		n->vqs[i].ubuf_info =
+			kmalloc_array(UIO_MAXIOV,
+				      sizeof(*n->vqs[i].ubuf_info),
+				      GFP_KERNEL);
+		if  (!n->vqs[i].ubuf_info)
+			goto err;
+	}
+	return 0;
+
+err:
+	vhost_net_clear_ubuf_info(n);
+	return -ENOMEM;
+}
+
+static void vhost_net_vq_reset(struct vhost_net *n)
+{
+	int i;
+
+	vhost_net_clear_ubuf_info(n);
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+		n->vqs[i].done_idx = 0;
+		n->vqs[i].upend_idx = 0;
+		n->vqs[i].ubufs = NULL;
+		n->vqs[i].vhost_hlen = 0;
+		n->vqs[i].sock_hlen = 0;
+		vhost_net_buf_init(&n->vqs[i].rxq);
+	}
+
+}
+
+static void vhost_net_tx_packet(struct vhost_net *net)
+{
+	++net->tx_packets;
+	if (net->tx_packets < 1024)
+		return;
+	net->tx_packets = 0;
+	net->tx_zcopy_err = 0;
+}
+
+static void vhost_net_tx_err(struct vhost_net *net)
+{
+	++net->tx_zcopy_err;
+}
+
+static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
+{
+	/* TX flush waits for outstanding DMAs to be done.
+	 * Don't start new DMAs.
+	 */
+	return !net->tx_flush &&
+		net->tx_packets / 64 >= net->tx_zcopy_err;
+}
+
+static bool vhost_sock_zcopy(struct socket *sock)
+{
+	return unlikely(experimental_zcopytx) &&
+		sock_flag(sock->sk, SOCK_ZEROCOPY);
+}
+
+static bool vhost_sock_xdp(struct socket *sock)
+{
+	return sock_flag(sock->sk, SOCK_XDP);
+}
+
+/* In case of DMA done not in order in lower device driver for some reason.
+ * upend_idx is used to track end of used idx, done_idx is used to track head
+ * of used idx. Once lower device DMA done contiguously, we will signal KVM
+ * guest used idx.
+ */
+static void vhost_zerocopy_signal_used(struct vhost_net *net,
+				       struct vhost_virtqueue *vq)
+{
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	int i, add;
+	int j = 0;
+
+	for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
+		if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
+			vhost_net_tx_err(net);
+		if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
+			vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
+			++j;
+		} else
+			break;
+	}
+	while (j) {
+		add = min(UIO_MAXIOV - nvq->done_idx, j);
+		vhost_add_used_and_signal_n(vq->dev, vq,
+					    &vq->heads[nvq->done_idx], add);
+		nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
+		j -= add;
+	}
+}
+
+static void vhost_zerocopy_callback(struct sk_buff *skb,
+				    struct ubuf_info *ubuf_base, bool success)
+{
+	struct ubuf_info_msgzc *ubuf = uarg_to_msgzc(ubuf_base);
+	struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
+	struct vhost_virtqueue *vq = ubufs->vq;
+	int cnt;
+
+	rcu_read_lock_bh();
+
+	/* set len to mark this desc buffers done DMA */
+	vq->heads[ubuf->desc].len = success ?
+		VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
+	cnt = vhost_net_ubuf_put(ubufs);
+
+	/*
+	 * Trigger polling thread if guest stopped submitting new buffers:
+	 * in this case, the refcount after decrement will eventually reach 1.
+	 * We also trigger polling periodically after each 16 packets
+	 * (the value 16 here is more or less arbitrary, it's tuned to trigger
+	 * less than 10% of times).
+	 */
+	if (cnt <= 1 || !(cnt % 16))
+		vhost_poll_queue(&vq->poll);
+
+	rcu_read_unlock_bh();
+}
+
+static inline unsigned long busy_clock(void)
+{
+	return local_clock() >> 10;
+}
+
+static bool vhost_can_busy_poll(unsigned long endtime)
+{
+	return likely(!need_resched() && !time_after(busy_clock(), endtime) &&
+		      !signal_pending(current));
+}
+
+static void vhost_net_disable_vq(struct vhost_net *n,
+				 struct vhost_virtqueue *vq)
+{
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
+	if (!vhost_vq_get_backend(vq))
+		return;
+	vhost_poll_stop(poll);
+}
+
+static int vhost_net_enable_vq(struct vhost_net *n,
+				struct vhost_virtqueue *vq)
+{
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
+	struct socket *sock;
+
+	sock = vhost_vq_get_backend(vq);
+	if (!sock)
+		return 0;
+
+	return vhost_poll_start(poll, sock->file);
+}
+
+static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
+{
+	struct vhost_virtqueue *vq = &nvq->vq;
+	struct vhost_dev *dev = vq->dev;
+
+	if (!nvq->done_idx)
+		return;
+
+	vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
+	nvq->done_idx = 0;
+}
+
+static void vhost_tx_batch(struct vhost_net *net,
+			   struct vhost_net_virtqueue *nvq,
+			   struct socket *sock,
+			   struct msghdr *msghdr)
+{
+	struct tun_msg_ctl ctl = {
+		.type = TUN_MSG_PTR,
+		.num = nvq->batched_xdp,
+		.ptr = nvq->xdp,
+	};
+	int i, err;
+
+	if (nvq->batched_xdp == 0)
+		goto signal_used;
+
+	msghdr->msg_control = &ctl;
+	msghdr->msg_controllen = sizeof(ctl);
+	err = sock->ops->sendmsg(sock, msghdr, 0);
+	if (unlikely(err < 0)) {
+		vq_err(&nvq->vq, "Fail to batch sending packets\n");
+
+		/* free pages owned by XDP; since this is an unlikely error path,
+		 * keep it simple and avoid more complex bulk update for the
+		 * used pages
+		 */
+		for (i = 0; i < nvq->batched_xdp; ++i)
+			put_page(virt_to_head_page(nvq->xdp[i].data));
+		nvq->batched_xdp = 0;
+		nvq->done_idx = 0;
+		return;
+	}
+
+signal_used:
+	vhost_net_signal_used(nvq);
+	nvq->batched_xdp = 0;
+}
+
+static int sock_has_rx_data(struct socket *sock)
+{
+	if (unlikely(!sock))
+		return 0;
+
+	if (sock->ops->peek_len)
+		return sock->ops->peek_len(sock);
+
+	return skb_queue_empty(&sock->sk->sk_receive_queue);
+}
+
+static void vhost_net_busy_poll_try_queue(struct vhost_net *net,
+					  struct vhost_virtqueue *vq)
+{
+	if (!vhost_vq_avail_empty(&net->dev, vq)) {
+		vhost_poll_queue(&vq->poll);
+	} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+		vhost_disable_notify(&net->dev, vq);
+		vhost_poll_queue(&vq->poll);
+	}
+}
+
+static void vhost_net_busy_poll(struct vhost_net *net,
+				struct vhost_virtqueue *rvq,
+				struct vhost_virtqueue *tvq,
+				bool *busyloop_intr,
+				bool poll_rx)
+{
+	unsigned long busyloop_timeout;
+	unsigned long endtime;
+	struct socket *sock;
+	struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;
+
+	/* Try to hold the vq mutex of the paired virtqueue. We can't
+	 * use mutex_lock() here since we could not guarantee a
+	 * consistenet lock ordering.
+	 */
+	if (!mutex_trylock(&vq->mutex))
+		return;
+
+	vhost_disable_notify(&net->dev, vq);
+	sock = vhost_vq_get_backend(rvq);
+
+	busyloop_timeout = poll_rx ? rvq->busyloop_timeout:
+				     tvq->busyloop_timeout;
+
+	preempt_disable();
+	endtime = busy_clock() + busyloop_timeout;
+
+	while (vhost_can_busy_poll(endtime)) {
+		if (vhost_vq_has_work(vq)) {
+			*busyloop_intr = true;
+			break;
+		}
+
+		if ((sock_has_rx_data(sock) &&
+		     !vhost_vq_avail_empty(&net->dev, rvq)) ||
+		    !vhost_vq_avail_empty(&net->dev, tvq))
+			break;
+
+		cpu_relax();
+	}
+
+	preempt_enable();
+
+	if (poll_rx || sock_has_rx_data(sock))
+		vhost_net_busy_poll_try_queue(net, vq);
+	else if (!poll_rx) /* On tx here, sock has no rx data. */
+		vhost_enable_notify(&net->dev, rvq);
+
+	mutex_unlock(&vq->mutex);
+}
+
+static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
+				    struct vhost_net_virtqueue *tnvq,
+				    unsigned int *out_num, unsigned int *in_num,
+				    struct msghdr *msghdr, bool *busyloop_intr)
+{
+	struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
+	struct vhost_virtqueue *rvq = &rnvq->vq;
+	struct vhost_virtqueue *tvq = &tnvq->vq;
+
+	int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
+				  out_num, in_num, NULL, NULL);
+
+	if (r == tvq->num && tvq->busyloop_timeout) {
+		/* Flush batched packets first */
+		if (!vhost_sock_zcopy(vhost_vq_get_backend(tvq)))
+			vhost_tx_batch(net, tnvq,
+				       vhost_vq_get_backend(tvq),
+				       msghdr);
+
+		vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);
+
+		r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
+				      out_num, in_num, NULL, NULL);
+	}
+
+	return r;
+}
+
+static bool vhost_exceeds_maxpend(struct vhost_net *net)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+
+	return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
+	       min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
+}
+
+static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
+			    size_t hdr_size, int out)
+{
+	/* Skip header. TODO: support TSO. */
+	size_t len = iov_length(vq->iov, out);
+
+	iov_iter_init(iter, ITER_SOURCE, vq->iov, out, len);
+	iov_iter_advance(iter, hdr_size);
+
+	return iov_iter_count(iter);
+}
+
+static int get_tx_bufs(struct vhost_net *net,
+		       struct vhost_net_virtqueue *nvq,
+		       struct msghdr *msg,
+		       unsigned int *out, unsigned int *in,
+		       size_t *len, bool *busyloop_intr)
+{
+	struct vhost_virtqueue *vq = &nvq->vq;
+	int ret;
+
+	ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, msg, busyloop_intr);
+
+	if (ret < 0 || ret == vq->num)
+		return ret;
+
+	if (*in) {
+		vq_err(vq, "Unexpected descriptor format for TX: out %d, int %d\n",
+			*out, *in);
+		return -EFAULT;
+	}
+
+	/* Sanity check */
+	*len = init_iov_iter(vq, &msg->msg_iter, nvq->vhost_hlen, *out);
+	if (*len == 0) {
+		vq_err(vq, "Unexpected header len for TX: %zd expected %zd\n",
+			*len, nvq->vhost_hlen);
+		return -EFAULT;
+	}
+
+	return ret;
+}
+
+static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
+{
+	return total_len < VHOST_NET_WEIGHT &&
+	       !vhost_vq_avail_empty(vq->dev, vq);
+}
+
+static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz,
+				       struct page_frag *pfrag, gfp_t gfp)
+{
+	if (pfrag->page) {
+		if (pfrag->offset + sz <= pfrag->size)
+			return true;
+		__page_frag_cache_drain(pfrag->page, net->refcnt_bias);
+	}
+
+	pfrag->offset = 0;
+	net->refcnt_bias = 0;
+	if (SKB_FRAG_PAGE_ORDER) {
+		/* Avoid direct reclaim but allow kswapd to wake */
+		pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
+					  __GFP_COMP | __GFP_NOWARN |
+					  __GFP_NORETRY,
+					  SKB_FRAG_PAGE_ORDER);
+		if (likely(pfrag->page)) {
+			pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
+			goto done;
+		}
+	}
+	pfrag->page = alloc_page(gfp);
+	if (likely(pfrag->page)) {
+		pfrag->size = PAGE_SIZE;
+		goto done;
+	}
+	return false;
+
+done:
+	net->refcnt_bias = USHRT_MAX;
+	page_ref_add(pfrag->page, USHRT_MAX - 1);
+	return true;
+}
+
+#define VHOST_NET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
+
+static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
+			       struct iov_iter *from)
+{
+	struct vhost_virtqueue *vq = &nvq->vq;
+	struct vhost_net *net = container_of(vq->dev, struct vhost_net,
+					     dev);
+	struct socket *sock = vhost_vq_get_backend(vq);
+	struct page_frag *alloc_frag = &net->page_frag;
+	struct virtio_net_hdr *gso;
+	struct xdp_buff *xdp = &nvq->xdp[nvq->batched_xdp];
+	struct tun_xdp_hdr *hdr;
+	size_t len = iov_iter_count(from);
+	int headroom = vhost_sock_xdp(sock) ? XDP_PACKET_HEADROOM : 0;
+	int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+	int pad = SKB_DATA_ALIGN(VHOST_NET_RX_PAD + headroom + nvq->sock_hlen);
+	int sock_hlen = nvq->sock_hlen;
+	void *buf;
+	int copied;
+
+	if (unlikely(len < nvq->sock_hlen))
+		return -EFAULT;
+
+	if (SKB_DATA_ALIGN(len + pad) +
+	    SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE)
+		return -ENOSPC;
+
+	buflen += SKB_DATA_ALIGN(len + pad);
+	alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
+	if (unlikely(!vhost_net_page_frag_refill(net, buflen,
+						 alloc_frag, GFP_KERNEL)))
+		return -ENOMEM;
+
+	buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
+	copied = copy_page_from_iter(alloc_frag->page,
+				     alloc_frag->offset +
+				     offsetof(struct tun_xdp_hdr, gso),
+				     sock_hlen, from);
+	if (copied != sock_hlen)
+		return -EFAULT;
+
+	hdr = buf;
+	gso = &hdr->gso;
+
+	if ((gso->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
+	    vhost16_to_cpu(vq, gso->csum_start) +
+	    vhost16_to_cpu(vq, gso->csum_offset) + 2 >
+	    vhost16_to_cpu(vq, gso->hdr_len)) {
+		gso->hdr_len = cpu_to_vhost16(vq,
+			       vhost16_to_cpu(vq, gso->csum_start) +
+			       vhost16_to_cpu(vq, gso->csum_offset) + 2);
+
+		if (vhost16_to_cpu(vq, gso->hdr_len) > len)
+			return -EINVAL;
+	}
+
+	len -= sock_hlen;
+	copied = copy_page_from_iter(alloc_frag->page,
+				     alloc_frag->offset + pad,
+				     len, from);
+	if (copied != len)
+		return -EFAULT;
+
+	xdp_init_buff(xdp, buflen, NULL);
+	xdp_prepare_buff(xdp, buf, pad, len, true);
+	hdr->buflen = buflen;
+
+	--net->refcnt_bias;
+	alloc_frag->offset += buflen;
+
+	++nvq->batched_xdp;
+
+	return 0;
+}
+
+static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+	unsigned out, in;
+	int head;
+	struct msghdr msg = {
+		.msg_name = NULL,
+		.msg_namelen = 0,
+		.msg_control = NULL,
+		.msg_controllen = 0,
+		.msg_flags = MSG_DONTWAIT,
+	};
+	size_t len, total_len = 0;
+	int err;
+	int sent_pkts = 0;
+	bool sock_can_batch = (sock->sk->sk_sndbuf == INT_MAX);
+
+	do {
+		bool busyloop_intr = false;
+
+		if (nvq->done_idx == VHOST_NET_BATCH)
+			vhost_tx_batch(net, nvq, sock, &msg);
+
+		head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
+				   &busyloop_intr);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(head < 0))
+			break;
+		/* Nothing new?  Wait for eventfd to tell us they refilled. */
+		if (head == vq->num) {
+			if (unlikely(busyloop_intr)) {
+				vhost_poll_queue(&vq->poll);
+			} else if (unlikely(vhost_enable_notify(&net->dev,
+								vq))) {
+				vhost_disable_notify(&net->dev, vq);
+				continue;
+			}
+			break;
+		}
+
+		total_len += len;
+
+		/* For simplicity, TX batching is only enabled if
+		 * sndbuf is unlimited.
+		 */
+		if (sock_can_batch) {
+			err = vhost_net_build_xdp(nvq, &msg.msg_iter);
+			if (!err) {
+				goto done;
+			} else if (unlikely(err != -ENOSPC)) {
+				vhost_tx_batch(net, nvq, sock, &msg);
+				vhost_discard_vq_desc(vq, 1);
+				vhost_net_enable_vq(net, vq);
+				break;
+			}
+
+			/* We can't build XDP buff, go for single
+			 * packet path but let's flush batched
+			 * packets.
+			 */
+			vhost_tx_batch(net, nvq, sock, &msg);
+			msg.msg_control = NULL;
+		} else {
+			if (tx_can_batch(vq, total_len))
+				msg.msg_flags |= MSG_MORE;
+			else
+				msg.msg_flags &= ~MSG_MORE;
+		}
+
+		err = sock->ops->sendmsg(sock, &msg, len);
+		if (unlikely(err < 0)) {
+			if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) {
+				vhost_discard_vq_desc(vq, 1);
+				vhost_net_enable_vq(net, vq);
+				break;
+			}
+			pr_debug("Fail to send packet: err %d", err);
+		} else if (unlikely(err != len))
+			pr_debug("Truncated TX packet: len %d != %zd\n",
+				 err, len);
+done:
+		vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
+		vq->heads[nvq->done_idx].len = 0;
+		++nvq->done_idx;
+	} while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
+
+	vhost_tx_batch(net, nvq, sock, &msg);
+}
+
+static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+	unsigned out, in;
+	int head;
+	struct msghdr msg = {
+		.msg_name = NULL,
+		.msg_namelen = 0,
+		.msg_control = NULL,
+		.msg_controllen = 0,
+		.msg_flags = MSG_DONTWAIT,
+	};
+	struct tun_msg_ctl ctl;
+	size_t len, total_len = 0;
+	int err;
+	struct vhost_net_ubuf_ref *ubufs;
+	struct ubuf_info_msgzc *ubuf;
+	bool zcopy_used;
+	int sent_pkts = 0;
+
+	do {
+		bool busyloop_intr;
+
+		/* Release DMAs done buffers first */
+		vhost_zerocopy_signal_used(net, vq);
+
+		busyloop_intr = false;
+		head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
+				   &busyloop_intr);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(head < 0))
+			break;
+		/* Nothing new?  Wait for eventfd to tell us they refilled. */
+		if (head == vq->num) {
+			if (unlikely(busyloop_intr)) {
+				vhost_poll_queue(&vq->poll);
+			} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+				vhost_disable_notify(&net->dev, vq);
+				continue;
+			}
+			break;
+		}
+
+		zcopy_used = len >= VHOST_GOODCOPY_LEN
+			     && !vhost_exceeds_maxpend(net)
+			     && vhost_net_tx_select_zcopy(net);
+
+		/* use msg_control to pass vhost zerocopy ubuf info to skb */
+		if (zcopy_used) {
+			ubuf = nvq->ubuf_info + nvq->upend_idx;
+			vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
+			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
+			ubuf->ctx = nvq->ubufs;
+			ubuf->desc = nvq->upend_idx;
+			ubuf->ubuf.callback = vhost_zerocopy_callback;
+			ubuf->ubuf.flags = SKBFL_ZEROCOPY_FRAG;
+			refcount_set(&ubuf->ubuf.refcnt, 1);
+			msg.msg_control = &ctl;
+			ctl.type = TUN_MSG_UBUF;
+			ctl.ptr = &ubuf->ubuf;
+			msg.msg_controllen = sizeof(ctl);
+			ubufs = nvq->ubufs;
+			atomic_inc(&ubufs->refcount);
+			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
+		} else {
+			msg.msg_control = NULL;
+			ubufs = NULL;
+		}
+		total_len += len;
+		if (tx_can_batch(vq, total_len) &&
+		    likely(!vhost_exceeds_maxpend(net))) {
+			msg.msg_flags |= MSG_MORE;
+		} else {
+			msg.msg_flags &= ~MSG_MORE;
+		}
+
+		err = sock->ops->sendmsg(sock, &msg, len);
+		if (unlikely(err < 0)) {
+			bool retry = err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS;
+
+			if (zcopy_used) {
+				if (vq->heads[ubuf->desc].len == VHOST_DMA_IN_PROGRESS)
+					vhost_net_ubuf_put(ubufs);
+				if (retry)
+					nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
+						% UIO_MAXIOV;
+				else
+					vq->heads[ubuf->desc].len = VHOST_DMA_DONE_LEN;
+			}
+			if (retry) {
+				vhost_discard_vq_desc(vq, 1);
+				vhost_net_enable_vq(net, vq);
+				break;
+			}
+			pr_debug("Fail to send packet: err %d", err);
+		} else if (unlikely(err != len))
+			pr_debug("Truncated TX packet: "
+				 " len %d != %zd\n", err, len);
+		if (!zcopy_used)
+			vhost_add_used_and_signal(&net->dev, vq, head, 0);
+		else
+			vhost_zerocopy_signal_used(net, vq);
+		vhost_net_tx_packet(net);
+	} while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
+}
+
+/* Expects to be always run from workqueue - which acts as
+ * read-size critical section for our kind of RCU. */
+static void handle_tx(struct vhost_net *net)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+	struct socket *sock;
+
+	mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
+	sock = vhost_vq_get_backend(vq);
+	if (!sock)
+		goto out;
+
+	if (!vq_meta_prefetch(vq))
+		goto out;
+
+	vhost_disable_notify(&net->dev, vq);
+	vhost_net_disable_vq(net, vq);
+
+	if (vhost_sock_zcopy(sock))
+		handle_tx_zerocopy(net, sock);
+	else
+		handle_tx_copy(net, sock);
+
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
+{
+	struct sk_buff *head;
+	int len = 0;
+	unsigned long flags;
+
+	if (rvq->rx_ring)
+		return vhost_net_buf_peek(rvq);
+
+	spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
+	head = skb_peek(&sk->sk_receive_queue);
+	if (likely(head)) {
+		len = head->len;
+		if (skb_vlan_tag_present(head))
+			len += VLAN_HLEN;
+	}
+
+	spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
+	return len;
+}
+
+static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
+				      bool *busyloop_intr)
+{
+	struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
+	struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *rvq = &rnvq->vq;
+	struct vhost_virtqueue *tvq = &tnvq->vq;
+	int len = peek_head_len(rnvq, sk);
+
+	if (!len && rvq->busyloop_timeout) {
+		/* Flush batched heads first */
+		vhost_net_signal_used(rnvq);
+		/* Both tx vq and rx socket were polled here */
+		vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
+
+		len = peek_head_len(rnvq, sk);
+	}
+
+	return len;
+}
+
+/* This is a multi-buffer version of vhost_get_desc, that works if
+ *	vq has read descriptors only.
+ * @vq		- the relevant virtqueue
+ * @datalen	- data length we'll be reading
+ * @iovcount	- returned count of io vectors we fill
+ * @log		- vhost log
+ * @log_num	- log offset
+ * @quota       - headcount quota, 1 for big buffer
+ *	returns number of buffer heads allocated, negative on error
+ */
+static int get_rx_bufs(struct vhost_virtqueue *vq,
+		       struct vring_used_elem *heads,
+		       int datalen,
+		       unsigned *iovcount,
+		       struct vhost_log *log,
+		       unsigned *log_num,
+		       unsigned int quota)
+{
+	unsigned int out, in;
+	int seg = 0;
+	int headcount = 0;
+	unsigned d;
+	int r, nlogs = 0;
+	/* len is always initialized before use since we are always called with
+	 * datalen > 0.
+	 */
+	u32 len;
+
+	while (datalen > 0 && headcount < quota) {
+		if (unlikely(seg >= UIO_MAXIOV)) {
+			r = -ENOBUFS;
+			goto err;
+		}
+		r = vhost_get_vq_desc(vq, vq->iov + seg,
+				      ARRAY_SIZE(vq->iov) - seg, &out,
+				      &in, log, log_num);
+		if (unlikely(r < 0))
+			goto err;
+
+		d = r;
+		if (d == vq->num) {
+			r = 0;
+			goto err;
+		}
+		if (unlikely(out || in <= 0)) {
+			vq_err(vq, "unexpected descriptor format for RX: "
+				"out %d, in %d\n", out, in);
+			r = -EINVAL;
+			goto err;
+		}
+		if (unlikely(log)) {
+			nlogs += *log_num;
+			log += *log_num;
+		}
+		heads[headcount].id = cpu_to_vhost32(vq, d);
+		len = iov_length(vq->iov + seg, in);
+		heads[headcount].len = cpu_to_vhost32(vq, len);
+		datalen -= len;
+		++headcount;
+		seg += in;
+	}
+	heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
+	*iovcount = seg;
+	if (unlikely(log))
+		*log_num = nlogs;
+
+	/* Detect overrun */
+	if (unlikely(datalen > 0)) {
+		r = UIO_MAXIOV + 1;
+		goto err;
+	}
+	return headcount;
+err:
+	vhost_discard_vq_desc(vq, headcount);
+	return r;
+}
+
+/* Expects to be always run from workqueue - which acts as
+ * read-size critical section for our kind of RCU. */
+static void handle_rx(struct vhost_net *net)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+	unsigned in, log;
+	struct vhost_log *vq_log;
+	struct msghdr msg = {
+		.msg_name = NULL,
+		.msg_namelen = 0,
+		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
+		.msg_controllen = 0,
+		.msg_flags = MSG_DONTWAIT,
+	};
+	struct virtio_net_hdr hdr = {
+		.flags = 0,
+		.gso_type = VIRTIO_NET_HDR_GSO_NONE
+	};
+	size_t total_len = 0;
+	int err, mergeable;
+	s16 headcount;
+	size_t vhost_hlen, sock_hlen;
+	size_t vhost_len, sock_len;
+	bool busyloop_intr = false;
+	struct socket *sock;
+	struct iov_iter fixup;
+	__virtio16 num_buffers;
+	int recv_pkts = 0;
+
+	mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
+	sock = vhost_vq_get_backend(vq);
+	if (!sock)
+		goto out;
+
+	if (!vq_meta_prefetch(vq))
+		goto out;
+
+	vhost_disable_notify(&net->dev, vq);
+	vhost_net_disable_vq(net, vq);
+
+	vhost_hlen = nvq->vhost_hlen;
+	sock_hlen = nvq->sock_hlen;
+
+	vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
+		vq->log : NULL;
+	mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
+
+	do {
+		sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
+						      &busyloop_intr);
+		if (!sock_len)
+			break;
+		sock_len += sock_hlen;
+		vhost_len = sock_len + vhost_hlen;
+		headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
+					vhost_len, &in, vq_log, &log,
+					likely(mergeable) ? UIO_MAXIOV : 1);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(headcount < 0))
+			goto out;
+		/* OK, now we need to know about added descriptors. */
+		if (!headcount) {
+			if (unlikely(busyloop_intr)) {
+				vhost_poll_queue(&vq->poll);
+			} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+				/* They have slipped one in as we were
+				 * doing that: check again. */
+				vhost_disable_notify(&net->dev, vq);
+				continue;
+			}
+			/* Nothing new?  Wait for eventfd to tell us
+			 * they refilled. */
+			goto out;
+		}
+		busyloop_intr = false;
+		if (nvq->rx_ring)
+			msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
+		/* On overrun, truncate and discard */
+		if (unlikely(headcount > UIO_MAXIOV)) {
+			iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, 1, 1);
+			err = sock->ops->recvmsg(sock, &msg,
+						 1, MSG_DONTWAIT | MSG_TRUNC);
+			pr_debug("Discarded rx packet: len %zd\n", sock_len);
+			continue;
+		}
+		/* We don't need to be notified again. */
+		iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, in, vhost_len);
+		fixup = msg.msg_iter;
+		if (unlikely((vhost_hlen))) {
+			/* We will supply the header ourselves
+			 * TODO: support TSO.
+			 */
+			iov_iter_advance(&msg.msg_iter, vhost_hlen);
+		}
+		err = sock->ops->recvmsg(sock, &msg,
+					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
+		/* Userspace might have consumed the packet meanwhile:
+		 * it's not supposed to do this usually, but might be hard
+		 * to prevent. Discard data we got (if any) and keep going. */
+		if (unlikely(err != sock_len)) {
+			pr_debug("Discarded rx packet: "
+				 " len %d, expected %zd\n", err, sock_len);
+			vhost_discard_vq_desc(vq, headcount);
+			continue;
+		}
+		/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
+		if (unlikely(vhost_hlen)) {
+			if (copy_to_iter(&hdr, sizeof(hdr),
+					 &fixup) != sizeof(hdr)) {
+				vq_err(vq, "Unable to write vnet_hdr "
+				       "at addr %p\n", vq->iov->iov_base);
+				goto out;
+			}
+		} else {
+			/* Header came from socket; we'll need to patch
+			 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
+			 */
+			iov_iter_advance(&fixup, sizeof(hdr));
+		}
+		/* TODO: Should check and handle checksum. */
+
+		num_buffers = cpu_to_vhost16(vq, headcount);
+		if (likely(mergeable) &&
+		    copy_to_iter(&num_buffers, sizeof num_buffers,
+				 &fixup) != sizeof num_buffers) {
+			vq_err(vq, "Failed num_buffers write");
+			vhost_discard_vq_desc(vq, headcount);
+			goto out;
+		}
+		nvq->done_idx += headcount;
+		if (nvq->done_idx > VHOST_NET_BATCH)
+			vhost_net_signal_used(nvq);
+		if (unlikely(vq_log))
+			vhost_log_write(vq, vq_log, log, vhost_len,
+					vq->iov, in);
+		total_len += vhost_len;
+	} while (likely(!vhost_exceeds_weight(vq, ++recv_pkts, total_len)));
+
+	if (unlikely(busyloop_intr))
+		vhost_poll_queue(&vq->poll);
+	else if (!sock_len)
+		vhost_net_enable_vq(net, vq);
+out:
+	vhost_net_signal_used(nvq);
+	mutex_unlock(&vq->mutex);
+}
+
+static void handle_tx_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
+
+	handle_tx(net);
+}
+
+static void handle_rx_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
+
+	handle_rx(net);
+}
+
+static void handle_tx_net(struct vhost_work *work)
+{
+	struct vhost_net *net = container_of(work, struct vhost_net,
+					     poll[VHOST_NET_VQ_TX].work);
+	handle_tx(net);
+}
+
+static void handle_rx_net(struct vhost_work *work)
+{
+	struct vhost_net *net = container_of(work, struct vhost_net,
+					     poll[VHOST_NET_VQ_RX].work);
+	handle_rx(net);
+}
+
+static int vhost_net_open(struct inode *inode, struct file *f)
+{
+	struct vhost_net *n;
+	struct vhost_dev *dev;
+	struct vhost_virtqueue **vqs;
+	void **queue;
+	struct xdp_buff *xdp;
+	int i;
+
+	n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (!n)
+		return -ENOMEM;
+	vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		kvfree(n);
+		return -ENOMEM;
+	}
+
+	queue = kmalloc_array(VHOST_NET_BATCH, sizeof(void *),
+			      GFP_KERNEL);
+	if (!queue) {
+		kfree(vqs);
+		kvfree(n);
+		return -ENOMEM;
+	}
+	n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
+
+	xdp = kmalloc_array(VHOST_NET_BATCH, sizeof(*xdp), GFP_KERNEL);
+	if (!xdp) {
+		kfree(vqs);
+		kvfree(n);
+		kfree(queue);
+		return -ENOMEM;
+	}
+	n->vqs[VHOST_NET_VQ_TX].xdp = xdp;
+
+	dev = &n->dev;
+	vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
+	vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
+	n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
+	n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
+	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+		n->vqs[i].ubufs = NULL;
+		n->vqs[i].ubuf_info = NULL;
+		n->vqs[i].upend_idx = 0;
+		n->vqs[i].done_idx = 0;
+		n->vqs[i].batched_xdp = 0;
+		n->vqs[i].vhost_hlen = 0;
+		n->vqs[i].sock_hlen = 0;
+		n->vqs[i].rx_ring = NULL;
+		vhost_net_buf_init(&n->vqs[i].rxq);
+	}
+	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
+		       UIO_MAXIOV + VHOST_NET_BATCH,
+		       VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT, true,
+		       NULL);
+
+	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev,
+			vqs[VHOST_NET_VQ_TX]);
+	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev,
+			vqs[VHOST_NET_VQ_RX]);
+
+	f->private_data = n;
+	n->page_frag.page = NULL;
+	n->refcnt_bias = 0;
+
+	return 0;
+}
+
+static struct socket *vhost_net_stop_vq(struct vhost_net *n,
+					struct vhost_virtqueue *vq)
+{
+	struct socket *sock;
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+
+	mutex_lock(&vq->mutex);
+	sock = vhost_vq_get_backend(vq);
+	vhost_net_disable_vq(n, vq);
+	vhost_vq_set_backend(vq, NULL);
+	vhost_net_buf_unproduce(nvq);
+	nvq->rx_ring = NULL;
+	mutex_unlock(&vq->mutex);
+	return sock;
+}
+
+static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
+			   struct socket **rx_sock)
+{
+	*tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
+	*rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
+}
+
+static void vhost_net_flush(struct vhost_net *n)
+{
+	vhost_dev_flush(&n->dev);
+	if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
+		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		n->tx_flush = true;
+		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		/* Wait for all lower device DMAs done. */
+		vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
+		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		n->tx_flush = false;
+		atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
+		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+	}
+}
+
+static int vhost_net_release(struct inode *inode, struct file *f)
+{
+	struct vhost_net *n = f->private_data;
+	struct socket *tx_sock;
+	struct socket *rx_sock;
+
+	vhost_net_stop(n, &tx_sock, &rx_sock);
+	vhost_net_flush(n);
+	vhost_dev_stop(&n->dev);
+	vhost_dev_cleanup(&n->dev);
+	vhost_net_vq_reset(n);
+	if (tx_sock)
+		sockfd_put(tx_sock);
+	if (rx_sock)
+		sockfd_put(rx_sock);
+	/* Make sure no callbacks are outstanding */
+	synchronize_rcu();
+	/* We do an extra flush before freeing memory,
+	 * since jobs can re-queue themselves. */
+	vhost_net_flush(n);
+	kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
+	kfree(n->vqs[VHOST_NET_VQ_TX].xdp);
+	kfree(n->dev.vqs);
+	if (n->page_frag.page)
+		__page_frag_cache_drain(n->page_frag.page, n->refcnt_bias);
+	kvfree(n);
+	return 0;
+}
+
+static struct socket *get_raw_socket(int fd)
+{
+	int r;
+	struct socket *sock = sockfd_lookup(fd, &r);
+
+	if (!sock)
+		return ERR_PTR(-ENOTSOCK);
+
+	/* Parameter checking */
+	if (sock->sk->sk_type != SOCK_RAW) {
+		r = -ESOCKTNOSUPPORT;
+		goto err;
+	}
+
+	if (sock->sk->sk_family != AF_PACKET) {
+		r = -EPFNOSUPPORT;
+		goto err;
+	}
+	return sock;
+err:
+	sockfd_put(sock);
+	return ERR_PTR(r);
+}
+
+static struct ptr_ring *get_tap_ptr_ring(struct file *file)
+{
+	struct ptr_ring *ring;
+	ring = tun_get_tx_ring(file);
+	if (!IS_ERR(ring))
+		goto out;
+	ring = tap_get_ptr_ring(file);
+	if (!IS_ERR(ring))
+		goto out;
+	ring = NULL;
+out:
+	return ring;
+}
+
+static struct socket *get_tap_socket(int fd)
+{
+	struct file *file = fget(fd);
+	struct socket *sock;
+
+	if (!file)
+		return ERR_PTR(-EBADF);
+	sock = tun_get_socket(file);
+	if (!IS_ERR(sock))
+		return sock;
+	sock = tap_get_socket(file);
+	if (IS_ERR(sock))
+		fput(file);
+	return sock;
+}
+
+static struct socket *get_socket(int fd)
+{
+	struct socket *sock;
+
+	/* special case to disable backend */
+	if (fd == -1)
+		return NULL;
+	sock = get_raw_socket(fd);
+	if (!IS_ERR(sock))
+		return sock;
+	sock = get_tap_socket(fd);
+	if (!IS_ERR(sock))
+		return sock;
+	return ERR_PTR(-ENOTSOCK);
+}
+
+static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
+{
+	struct socket *sock, *oldsock;
+	struct vhost_virtqueue *vq;
+	struct vhost_net_virtqueue *nvq;
+	struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
+	int r;
+
+	mutex_lock(&n->dev.mutex);
+	r = vhost_dev_check_owner(&n->dev);
+	if (r)
+		goto err;
+
+	if (index >= VHOST_NET_VQ_MAX) {
+		r = -ENOBUFS;
+		goto err;
+	}
+	vq = &n->vqs[index].vq;
+	nvq = &n->vqs[index];
+	mutex_lock(&vq->mutex);
+
+	if (fd == -1)
+		vhost_clear_msg(&n->dev);
+
+	/* Verify that ring has been setup correctly. */
+	if (!vhost_vq_access_ok(vq)) {
+		r = -EFAULT;
+		goto err_vq;
+	}
+	sock = get_socket(fd);
+	if (IS_ERR(sock)) {
+		r = PTR_ERR(sock);
+		goto err_vq;
+	}
+
+	/* start polling new socket */
+	oldsock = vhost_vq_get_backend(vq);
+	if (sock != oldsock) {
+		ubufs = vhost_net_ubuf_alloc(vq,
+					     sock && vhost_sock_zcopy(sock));
+		if (IS_ERR(ubufs)) {
+			r = PTR_ERR(ubufs);
+			goto err_ubufs;
+		}
+
+		vhost_net_disable_vq(n, vq);
+		vhost_vq_set_backend(vq, sock);
+		vhost_net_buf_unproduce(nvq);
+		r = vhost_vq_init_access(vq);
+		if (r)
+			goto err_used;
+		r = vhost_net_enable_vq(n, vq);
+		if (r)
+			goto err_used;
+		if (index == VHOST_NET_VQ_RX) {
+			if (sock)
+				nvq->rx_ring = get_tap_ptr_ring(sock->file);
+			else
+				nvq->rx_ring = NULL;
+		}
+
+		oldubufs = nvq->ubufs;
+		nvq->ubufs = ubufs;
+
+		n->tx_packets = 0;
+		n->tx_zcopy_err = 0;
+		n->tx_flush = false;
+	}
+
+	mutex_unlock(&vq->mutex);
+
+	if (oldubufs) {
+		vhost_net_ubuf_put_wait_and_free(oldubufs);
+		mutex_lock(&vq->mutex);
+		vhost_zerocopy_signal_used(n, vq);
+		mutex_unlock(&vq->mutex);
+	}
+
+	if (oldsock) {
+		vhost_dev_flush(&n->dev);
+		sockfd_put(oldsock);
+	}
+
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+
+err_used:
+	vhost_vq_set_backend(vq, oldsock);
+	vhost_net_enable_vq(n, vq);
+	if (ubufs)
+		vhost_net_ubuf_put_wait_and_free(ubufs);
+err_ubufs:
+	if (sock)
+		sockfd_put(sock);
+err_vq:
+	mutex_unlock(&vq->mutex);
+err:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
+static long vhost_net_reset_owner(struct vhost_net *n)
+{
+	struct socket *tx_sock = NULL;
+	struct socket *rx_sock = NULL;
+	long err;
+	struct vhost_iotlb *umem;
+
+	mutex_lock(&n->dev.mutex);
+	err = vhost_dev_check_owner(&n->dev);
+	if (err)
+		goto done;
+	umem = vhost_dev_reset_owner_prepare();
+	if (!umem) {
+		err = -ENOMEM;
+		goto done;
+	}
+	vhost_net_stop(n, &tx_sock, &rx_sock);
+	vhost_net_flush(n);
+	vhost_dev_stop(&n->dev);
+	vhost_dev_reset_owner(&n->dev, umem);
+	vhost_net_vq_reset(n);
+done:
+	mutex_unlock(&n->dev.mutex);
+	if (tx_sock)
+		sockfd_put(tx_sock);
+	if (rx_sock)
+		sockfd_put(rx_sock);
+	return err;
+}
+
+static int vhost_net_set_features(struct vhost_net *n, u64 features)
+{
+	size_t vhost_hlen, sock_hlen, hdr_len;
+	int i;
+
+	hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+			       (1ULL << VIRTIO_F_VERSION_1))) ?
+			sizeof(struct virtio_net_hdr_mrg_rxbuf) :
+			sizeof(struct virtio_net_hdr);
+	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
+		/* vhost provides vnet_hdr */
+		vhost_hlen = hdr_len;
+		sock_hlen = 0;
+	} else {
+		/* socket provides vnet_hdr */
+		vhost_hlen = 0;
+		sock_hlen = hdr_len;
+	}
+	mutex_lock(&n->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&n->dev))
+		goto out_unlock;
+
+	if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
+		if (vhost_init_device_iotlb(&n->dev))
+			goto out_unlock;
+	}
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		mutex_lock(&n->vqs[i].vq.mutex);
+		n->vqs[i].vq.acked_features = features;
+		n->vqs[i].vhost_hlen = vhost_hlen;
+		n->vqs[i].sock_hlen = sock_hlen;
+		mutex_unlock(&n->vqs[i].vq.mutex);
+	}
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&n->dev.mutex);
+	return -EFAULT;
+}
+
+static long vhost_net_set_owner(struct vhost_net *n)
+{
+	int r;
+
+	mutex_lock(&n->dev.mutex);
+	if (vhost_dev_has_owner(&n->dev)) {
+		r = -EBUSY;
+		goto out;
+	}
+	r = vhost_net_set_ubuf_info(n);
+	if (r)
+		goto out;
+	r = vhost_dev_set_owner(&n->dev);
+	if (r)
+		vhost_net_clear_ubuf_info(n);
+	vhost_net_flush(n);
+out:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
+static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
+			    unsigned long arg)
+{
+	struct vhost_net *n = f->private_data;
+	void __user *argp = (void __user *)arg;
+	u64 __user *featurep = argp;
+	struct vhost_vring_file backend;
+	u64 features;
+	int r;
+
+	switch (ioctl) {
+	case VHOST_NET_SET_BACKEND:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+		return vhost_net_set_backend(n, backend.index, backend.fd);
+	case VHOST_GET_FEATURES:
+		features = VHOST_NET_FEATURES;
+		if (copy_to_user(featurep, &features, sizeof features))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_FEATURES:
+		if (copy_from_user(&features, featurep, sizeof features))
+			return -EFAULT;
+		if (features & ~VHOST_NET_FEATURES)
+			return -EOPNOTSUPP;
+		return vhost_net_set_features(n, features);
+	case VHOST_GET_BACKEND_FEATURES:
+		features = VHOST_NET_BACKEND_FEATURES;
+		if (copy_to_user(featurep, &features, sizeof(features)))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_BACKEND_FEATURES:
+		if (copy_from_user(&features, featurep, sizeof(features)))
+			return -EFAULT;
+		if (features & ~VHOST_NET_BACKEND_FEATURES)
+			return -EOPNOTSUPP;
+		vhost_set_backend_features(&n->dev, features);
+		return 0;
+	case VHOST_RESET_OWNER:
+		return vhost_net_reset_owner(n);
+	case VHOST_SET_OWNER:
+		return vhost_net_set_owner(n);
+	default:
+		mutex_lock(&n->dev.mutex);
+		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vring_ioctl(&n->dev, ioctl, argp);
+		else
+			vhost_net_flush(n);
+		mutex_unlock(&n->dev.mutex);
+		return r;
+	}
+}
+
+static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct vhost_net *n = file->private_data;
+	struct vhost_dev *dev = &n->dev;
+	int noblock = file->f_flags & O_NONBLOCK;
+
+	return vhost_chr_read_iter(dev, to, noblock);
+}
+
+static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
+					struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct vhost_net *n = file->private_data;
+	struct vhost_dev *dev = &n->dev;
+
+	return vhost_chr_write_iter(dev, from);
+}
+
+static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
+{
+	struct vhost_net *n = file->private_data;
+	struct vhost_dev *dev = &n->dev;
+
+	return vhost_chr_poll(file, dev, wait);
+}
+
+static const struct file_operations vhost_net_fops = {
+	.owner          = THIS_MODULE,
+	.release        = vhost_net_release,
+	.read_iter      = vhost_net_chr_read_iter,
+	.write_iter     = vhost_net_chr_write_iter,
+	.poll           = vhost_net_chr_poll,
+	.unlocked_ioctl = vhost_net_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+	.open           = vhost_net_open,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice vhost_net_misc = {
+	.minor = VHOST_NET_MINOR,
+	.name = "vhost-net",
+	.fops = &vhost_net_fops,
+};
+
+static int __init vhost_net_init(void)
+{
+	if (experimental_zcopytx)
+		vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
+	return misc_register(&vhost_net_misc);
+}
+module_init(vhost_net_init);
+
+static void __exit vhost_net_exit(void)
+{
+	misc_deregister(&vhost_net_misc);
+}
+module_exit(vhost_net_exit);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Michael S. Tsirkin");
+MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
+MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
+MODULE_ALIAS("devname:vhost-net");
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
new file mode 100644
index 000000000..abef0619c
--- /dev/null
+++ b/drivers/vhost/scsi.c
@@ -0,0 +1,2637 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*******************************************************************************
+ * Vhost kernel TCM fabric driver for virtio SCSI initiators
+ *
+ * (C) Copyright 2010-2013 Datera, Inc.
+ * (C) Copyright 2010-2012 IBM Corp.
+ *
+ * Authors: Nicholas A. Bellinger <nab@daterainc.com>
+ *          Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
+ ****************************************************************************/
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <generated/utsrelease.h>
+#include <linux/utsname.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/configfs.h>
+#include <linux/ctype.h>
+#include <linux/compat.h>
+#include <linux/eventfd.h>
+#include <linux/fs.h>
+#include <linux/vmalloc.h>
+#include <linux/miscdevice.h>
+#include <linux/blk_types.h>
+#include <linux/bio.h>
+#include <asm/unaligned.h>
+#include <scsi/scsi_common.h>
+#include <scsi/scsi_proto.h>
+#include <target/target_core_base.h>
+#include <target/target_core_fabric.h>
+#include <linux/vhost.h>
+#include <linux/virtio_scsi.h>
+#include <linux/llist.h>
+#include <linux/bitmap.h>
+
+#include "vhost.h"
+
+#define VHOST_SCSI_VERSION  "v0.1"
+#define VHOST_SCSI_NAMELEN 256
+#define VHOST_SCSI_MAX_CDB_SIZE 32
+#define VHOST_SCSI_PREALLOC_SGLS 2048
+#define VHOST_SCSI_PREALLOC_UPAGES 2048
+#define VHOST_SCSI_PREALLOC_PROT_SGLS 2048
+
+/* Max number of requests before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others with
+ * request.
+ */
+#define VHOST_SCSI_WEIGHT 256
+
+struct vhost_scsi_inflight {
+	/* Wait for the flush operation to finish */
+	struct completion comp;
+	/* Refcount for the inflight reqs */
+	struct kref kref;
+};
+
+struct vhost_scsi_cmd {
+	/* Descriptor from vhost_get_vq_desc() for virt_queue segment */
+	int tvc_vq_desc;
+	/* virtio-scsi initiator task attribute */
+	int tvc_task_attr;
+	/* virtio-scsi response incoming iovecs */
+	int tvc_in_iovs;
+	/* virtio-scsi initiator data direction */
+	enum dma_data_direction tvc_data_direction;
+	/* Expected data transfer length from virtio-scsi header */
+	u32 tvc_exp_data_len;
+	/* The Tag from include/linux/virtio_scsi.h:struct virtio_scsi_cmd_req */
+	u64 tvc_tag;
+	/* The number of scatterlists associated with this cmd */
+	u32 tvc_sgl_count;
+	u32 tvc_prot_sgl_count;
+	/* Saved unpacked SCSI LUN for vhost_scsi_target_queue_cmd() */
+	u32 tvc_lun;
+	u32 copied_iov:1;
+	const void *saved_iter_addr;
+	struct iov_iter saved_iter;
+	/* Pointer to the SGL formatted memory from virtio-scsi */
+	struct scatterlist *tvc_sgl;
+	struct scatterlist *tvc_prot_sgl;
+	struct page **tvc_upages;
+	/* Pointer to response header iovec */
+	struct iovec *tvc_resp_iov;
+	/* Pointer to vhost_scsi for our device */
+	struct vhost_scsi *tvc_vhost;
+	/* Pointer to vhost_virtqueue for the cmd */
+	struct vhost_virtqueue *tvc_vq;
+	/* Pointer to vhost nexus memory */
+	struct vhost_scsi_nexus *tvc_nexus;
+	/* The TCM I/O descriptor that is accessed via container_of() */
+	struct se_cmd tvc_se_cmd;
+	/* Copy of the incoming SCSI command descriptor block (CDB) */
+	unsigned char tvc_cdb[VHOST_SCSI_MAX_CDB_SIZE];
+	/* Sense buffer that will be mapped into outgoing status */
+	unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER];
+	/* Completed commands list, serviced from vhost worker thread */
+	struct llist_node tvc_completion_list;
+	/* Used to track inflight cmd */
+	struct vhost_scsi_inflight *inflight;
+};
+
+struct vhost_scsi_nexus {
+	/* Pointer to TCM session for I_T Nexus */
+	struct se_session *tvn_se_sess;
+};
+
+struct vhost_scsi_tpg {
+	/* Vhost port target portal group tag for TCM */
+	u16 tport_tpgt;
+	/* Used to track number of TPG Port/Lun Links wrt to explict I_T Nexus shutdown */
+	int tv_tpg_port_count;
+	/* Used for vhost_scsi device reference to tpg_nexus, protected by tv_tpg_mutex */
+	int tv_tpg_vhost_count;
+	/* Used for enabling T10-PI with legacy devices */
+	int tv_fabric_prot_type;
+	/* list for vhost_scsi_list */
+	struct list_head tv_tpg_list;
+	/* Used to protect access for tpg_nexus */
+	struct mutex tv_tpg_mutex;
+	/* Pointer to the TCM VHost I_T Nexus for this TPG endpoint */
+	struct vhost_scsi_nexus *tpg_nexus;
+	/* Pointer back to vhost_scsi_tport */
+	struct vhost_scsi_tport *tport;
+	/* Returned by vhost_scsi_make_tpg() */
+	struct se_portal_group se_tpg;
+	/* Pointer back to vhost_scsi, protected by tv_tpg_mutex */
+	struct vhost_scsi *vhost_scsi;
+};
+
+struct vhost_scsi_tport {
+	/* SCSI protocol the tport is providing */
+	u8 tport_proto_id;
+	/* Binary World Wide unique Port Name for Vhost Target port */
+	u64 tport_wwpn;
+	/* ASCII formatted WWPN for Vhost Target port */
+	char tport_name[VHOST_SCSI_NAMELEN];
+	/* Returned by vhost_scsi_make_tport() */
+	struct se_wwn tport_wwn;
+};
+
+struct vhost_scsi_evt {
+	/* event to be sent to guest */
+	struct virtio_scsi_event event;
+	/* event list, serviced from vhost worker thread */
+	struct llist_node list;
+};
+
+enum {
+	VHOST_SCSI_VQ_CTL = 0,
+	VHOST_SCSI_VQ_EVT = 1,
+	VHOST_SCSI_VQ_IO = 2,
+};
+
+/* Note: can't set VIRTIO_F_VERSION_1 yet, since that implies ANY_LAYOUT. */
+enum {
+	VHOST_SCSI_FEATURES = VHOST_FEATURES | (1ULL << VIRTIO_SCSI_F_HOTPLUG) |
+					       (1ULL << VIRTIO_SCSI_F_T10_PI)
+};
+
+#define VHOST_SCSI_MAX_TARGET	256
+#define VHOST_SCSI_MAX_IO_VQ	1024
+#define VHOST_SCSI_MAX_EVENT	128
+
+static unsigned vhost_scsi_max_io_vqs = 128;
+module_param_named(max_io_vqs, vhost_scsi_max_io_vqs, uint, 0644);
+MODULE_PARM_DESC(max_io_vqs, "Set the max number of IO virtqueues a vhost scsi device can support. The default is 128. The max is 1024.");
+
+struct vhost_scsi_virtqueue {
+	struct vhost_virtqueue vq;
+	struct vhost_scsi *vs;
+	/*
+	 * Reference counting for inflight reqs, used for flush operation. At
+	 * each time, one reference tracks new commands submitted, while we
+	 * wait for another one to reach 0.
+	 */
+	struct vhost_scsi_inflight inflights[2];
+	/*
+	 * Indicate current inflight in use, protected by vq->mutex.
+	 * Writers must also take dev mutex and flush under it.
+	 */
+	int inflight_idx;
+	struct vhost_scsi_cmd *scsi_cmds;
+	struct sbitmap scsi_tags;
+	int max_cmds;
+
+	struct vhost_work completion_work;
+	struct llist_head completion_list;
+};
+
+struct vhost_scsi {
+	/* Protected by vhost_scsi->dev.mutex */
+	struct vhost_scsi_tpg **vs_tpg;
+	char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
+
+	struct vhost_dev dev;
+	struct vhost_scsi_virtqueue *vqs;
+	struct vhost_scsi_inflight **old_inflight;
+
+	struct vhost_work vs_event_work; /* evt injection work item */
+	struct llist_head vs_event_list; /* evt injection queue */
+
+	bool vs_events_missed; /* any missed events, protected by vq->mutex */
+	int vs_events_nr; /* num of pending events, protected by vq->mutex */
+};
+
+struct vhost_scsi_tmf {
+	struct vhost_work vwork;
+	struct vhost_scsi *vhost;
+	struct vhost_scsi_virtqueue *svq;
+
+	struct se_cmd se_cmd;
+	u8 scsi_resp;
+	struct vhost_scsi_inflight *inflight;
+	struct iovec resp_iov;
+	int in_iovs;
+	int vq_desc;
+};
+
+/*
+ * Context for processing request and control queue operations.
+ */
+struct vhost_scsi_ctx {
+	int head;
+	unsigned int out, in;
+	size_t req_size, rsp_size;
+	size_t out_size, in_size;
+	u8 *target, *lunp;
+	void *req;
+	struct iov_iter out_iter;
+};
+
+/*
+ * Global mutex to protect vhost_scsi TPG list for vhost IOCTLs and LIO
+ * configfs management operations.
+ */
+static DEFINE_MUTEX(vhost_scsi_mutex);
+static LIST_HEAD(vhost_scsi_list);
+
+static void vhost_scsi_done_inflight(struct kref *kref)
+{
+	struct vhost_scsi_inflight *inflight;
+
+	inflight = container_of(kref, struct vhost_scsi_inflight, kref);
+	complete(&inflight->comp);
+}
+
+static void vhost_scsi_init_inflight(struct vhost_scsi *vs,
+				    struct vhost_scsi_inflight *old_inflight[])
+{
+	struct vhost_scsi_inflight *new_inflight;
+	struct vhost_virtqueue *vq;
+	int idx, i;
+
+	for (i = 0; i < vs->dev.nvqs;  i++) {
+		vq = &vs->vqs[i].vq;
+
+		mutex_lock(&vq->mutex);
+
+		/* store old infight */
+		idx = vs->vqs[i].inflight_idx;
+		if (old_inflight)
+			old_inflight[i] = &vs->vqs[i].inflights[idx];
+
+		/* setup new infight */
+		vs->vqs[i].inflight_idx = idx ^ 1;
+		new_inflight = &vs->vqs[i].inflights[idx ^ 1];
+		kref_init(&new_inflight->kref);
+		init_completion(&new_inflight->comp);
+
+		mutex_unlock(&vq->mutex);
+	}
+}
+
+static struct vhost_scsi_inflight *
+vhost_scsi_get_inflight(struct vhost_virtqueue *vq)
+{
+	struct vhost_scsi_inflight *inflight;
+	struct vhost_scsi_virtqueue *svq;
+
+	svq = container_of(vq, struct vhost_scsi_virtqueue, vq);
+	inflight = &svq->inflights[svq->inflight_idx];
+	kref_get(&inflight->kref);
+
+	return inflight;
+}
+
+static void vhost_scsi_put_inflight(struct vhost_scsi_inflight *inflight)
+{
+	kref_put(&inflight->kref, vhost_scsi_done_inflight);
+}
+
+static int vhost_scsi_check_true(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static char *vhost_scsi_get_fabric_wwn(struct se_portal_group *se_tpg)
+{
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+	struct vhost_scsi_tport *tport = tpg->tport;
+
+	return &tport->tport_name[0];
+}
+
+static u16 vhost_scsi_get_tpgt(struct se_portal_group *se_tpg)
+{
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+	return tpg->tport_tpgt;
+}
+
+static int vhost_scsi_check_prot_fabric_only(struct se_portal_group *se_tpg)
+{
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+
+	return tpg->tv_fabric_prot_type;
+}
+
+static void vhost_scsi_release_cmd_res(struct se_cmd *se_cmd)
+{
+	struct vhost_scsi_cmd *tv_cmd = container_of(se_cmd,
+				struct vhost_scsi_cmd, tvc_se_cmd);
+	struct vhost_scsi_virtqueue *svq = container_of(tv_cmd->tvc_vq,
+				struct vhost_scsi_virtqueue, vq);
+	struct vhost_scsi_inflight *inflight = tv_cmd->inflight;
+	int i;
+
+	if (tv_cmd->tvc_sgl_count) {
+		for (i = 0; i < tv_cmd->tvc_sgl_count; i++) {
+			if (tv_cmd->copied_iov)
+				__free_page(sg_page(&tv_cmd->tvc_sgl[i]));
+			else
+				put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+		}
+		kfree(tv_cmd->saved_iter_addr);
+	}
+	if (tv_cmd->tvc_prot_sgl_count) {
+		for (i = 0; i < tv_cmd->tvc_prot_sgl_count; i++)
+			put_page(sg_page(&tv_cmd->tvc_prot_sgl[i]));
+	}
+
+	sbitmap_clear_bit(&svq->scsi_tags, se_cmd->map_tag);
+	vhost_scsi_put_inflight(inflight);
+}
+
+static void vhost_scsi_release_tmf_res(struct vhost_scsi_tmf *tmf)
+{
+	struct vhost_scsi_inflight *inflight = tmf->inflight;
+
+	kfree(tmf);
+	vhost_scsi_put_inflight(inflight);
+}
+
+static void vhost_scsi_release_cmd(struct se_cmd *se_cmd)
+{
+	if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) {
+		struct vhost_scsi_tmf *tmf = container_of(se_cmd,
+					struct vhost_scsi_tmf, se_cmd);
+		struct vhost_virtqueue *vq = &tmf->svq->vq;
+
+		vhost_vq_work_queue(vq, &tmf->vwork);
+	} else {
+		struct vhost_scsi_cmd *cmd = container_of(se_cmd,
+					struct vhost_scsi_cmd, tvc_se_cmd);
+		struct vhost_scsi_virtqueue *svq =  container_of(cmd->tvc_vq,
+					struct vhost_scsi_virtqueue, vq);
+
+		llist_add(&cmd->tvc_completion_list, &svq->completion_list);
+		vhost_vq_work_queue(&svq->vq, &svq->completion_work);
+	}
+}
+
+static int vhost_scsi_write_pending(struct se_cmd *se_cmd)
+{
+	/* Go ahead and process the write immediately */
+	target_execute_cmd(se_cmd);
+	return 0;
+}
+
+static int vhost_scsi_queue_data_in(struct se_cmd *se_cmd)
+{
+	transport_generic_free_cmd(se_cmd, 0);
+	return 0;
+}
+
+static int vhost_scsi_queue_status(struct se_cmd *se_cmd)
+{
+	transport_generic_free_cmd(se_cmd, 0);
+	return 0;
+}
+
+static void vhost_scsi_queue_tm_rsp(struct se_cmd *se_cmd)
+{
+	struct vhost_scsi_tmf *tmf = container_of(se_cmd, struct vhost_scsi_tmf,
+						  se_cmd);
+
+	tmf->scsi_resp = se_cmd->se_tmr_req->response;
+	transport_generic_free_cmd(&tmf->se_cmd, 0);
+}
+
+static void vhost_scsi_aborted_task(struct se_cmd *se_cmd)
+{
+	return;
+}
+
+static void vhost_scsi_free_evt(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
+{
+	vs->vs_events_nr--;
+	kfree(evt);
+}
+
+static struct vhost_scsi_evt *
+vhost_scsi_allocate_evt(struct vhost_scsi *vs,
+		       u32 event, u32 reason)
+{
+	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
+	struct vhost_scsi_evt *evt;
+
+	if (vs->vs_events_nr > VHOST_SCSI_MAX_EVENT) {
+		vs->vs_events_missed = true;
+		return NULL;
+	}
+
+	evt = kzalloc(sizeof(*evt), GFP_KERNEL);
+	if (!evt) {
+		vq_err(vq, "Failed to allocate vhost_scsi_evt\n");
+		vs->vs_events_missed = true;
+		return NULL;
+	}
+
+	evt->event.event = cpu_to_vhost32(vq, event);
+	evt->event.reason = cpu_to_vhost32(vq, reason);
+	vs->vs_events_nr++;
+
+	return evt;
+}
+
+static int vhost_scsi_check_stop_free(struct se_cmd *se_cmd)
+{
+	return target_put_sess_cmd(se_cmd);
+}
+
+static void
+vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
+{
+	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
+	struct virtio_scsi_event *event = &evt->event;
+	struct virtio_scsi_event __user *eventp;
+	unsigned out, in;
+	int head, ret;
+
+	if (!vhost_vq_get_backend(vq)) {
+		vs->vs_events_missed = true;
+		return;
+	}
+
+again:
+	vhost_disable_notify(&vs->dev, vq);
+	head = vhost_get_vq_desc(vq, vq->iov,
+			ARRAY_SIZE(vq->iov), &out, &in,
+			NULL, NULL);
+	if (head < 0) {
+		vs->vs_events_missed = true;
+		return;
+	}
+	if (head == vq->num) {
+		if (vhost_enable_notify(&vs->dev, vq))
+			goto again;
+		vs->vs_events_missed = true;
+		return;
+	}
+
+	if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {
+		vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes\n",
+				vq->iov[out].iov_len);
+		vs->vs_events_missed = true;
+		return;
+	}
+
+	if (vs->vs_events_missed) {
+		event->event |= cpu_to_vhost32(vq, VIRTIO_SCSI_T_EVENTS_MISSED);
+		vs->vs_events_missed = false;
+	}
+
+	eventp = vq->iov[out].iov_base;
+	ret = __copy_to_user(eventp, event, sizeof(*event));
+	if (!ret)
+		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+	else
+		vq_err(vq, "Faulted on vhost_scsi_send_event\n");
+}
+
+static void vhost_scsi_evt_work(struct vhost_work *work)
+{
+	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
+					vs_event_work);
+	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
+	struct vhost_scsi_evt *evt, *t;
+	struct llist_node *llnode;
+
+	mutex_lock(&vq->mutex);
+	llnode = llist_del_all(&vs->vs_event_list);
+	llist_for_each_entry_safe(evt, t, llnode, list) {
+		vhost_scsi_do_evt_work(vs, evt);
+		vhost_scsi_free_evt(vs, evt);
+	}
+	mutex_unlock(&vq->mutex);
+}
+
+static int vhost_scsi_copy_sgl_to_iov(struct vhost_scsi_cmd *cmd)
+{
+	struct iov_iter *iter = &cmd->saved_iter;
+	struct scatterlist *sg = cmd->tvc_sgl;
+	struct page *page;
+	size_t len;
+	int i;
+
+	for (i = 0; i < cmd->tvc_sgl_count; i++) {
+		page = sg_page(&sg[i]);
+		len = sg[i].length;
+
+		if (copy_page_to_iter(page, 0, len, iter) != len) {
+			pr_err("Could not copy data while handling misaligned cmd. Error %zu\n",
+			       len);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+/* Fill in status and signal that we are done processing this command
+ *
+ * This is scheduled in the vhost work queue so we are called with the owner
+ * process mm and can access the vring.
+ */
+static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
+{
+	struct vhost_scsi_virtqueue *svq = container_of(work,
+				struct vhost_scsi_virtqueue, completion_work);
+	struct virtio_scsi_cmd_resp v_rsp;
+	struct vhost_scsi_cmd *cmd, *t;
+	struct llist_node *llnode;
+	struct se_cmd *se_cmd;
+	struct iov_iter iov_iter;
+	bool signal = false;
+	int ret;
+
+	llnode = llist_del_all(&svq->completion_list);
+	llist_for_each_entry_safe(cmd, t, llnode, tvc_completion_list) {
+		se_cmd = &cmd->tvc_se_cmd;
+
+		pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
+			cmd, se_cmd->residual_count, se_cmd->scsi_status);
+		memset(&v_rsp, 0, sizeof(v_rsp));
+
+		if (cmd->saved_iter_addr && vhost_scsi_copy_sgl_to_iov(cmd)) {
+			v_rsp.response = VIRTIO_SCSI_S_BAD_TARGET;
+		} else {
+			v_rsp.resid = cpu_to_vhost32(cmd->tvc_vq,
+						     se_cmd->residual_count);
+			/* TODO is status_qualifier field needed? */
+			v_rsp.status = se_cmd->scsi_status;
+			v_rsp.sense_len = cpu_to_vhost32(cmd->tvc_vq,
+							 se_cmd->scsi_sense_length);
+			memcpy(v_rsp.sense, cmd->tvc_sense_buf,
+			       se_cmd->scsi_sense_length);
+		}
+
+		iov_iter_init(&iov_iter, ITER_DEST, cmd->tvc_resp_iov,
+			      cmd->tvc_in_iovs, sizeof(v_rsp));
+		ret = copy_to_iter(&v_rsp, sizeof(v_rsp), &iov_iter);
+		if (likely(ret == sizeof(v_rsp))) {
+			signal = true;
+
+			vhost_add_used(cmd->tvc_vq, cmd->tvc_vq_desc, 0);
+		} else
+			pr_err("Faulted on virtio_scsi_cmd_resp\n");
+
+		vhost_scsi_release_cmd_res(se_cmd);
+	}
+
+	if (signal)
+		vhost_signal(&svq->vs->dev, &svq->vq);
+}
+
+static struct vhost_scsi_cmd *
+vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
+		   unsigned char *cdb, u64 scsi_tag, u16 lun, u8 task_attr,
+		   u32 exp_data_len, int data_direction)
+{
+	struct vhost_scsi_virtqueue *svq = container_of(vq,
+					struct vhost_scsi_virtqueue, vq);
+	struct vhost_scsi_cmd *cmd;
+	struct vhost_scsi_nexus *tv_nexus;
+	struct scatterlist *sg, *prot_sg;
+	struct iovec *tvc_resp_iov;
+	struct page **pages;
+	int tag;
+
+	tv_nexus = tpg->tpg_nexus;
+	if (!tv_nexus) {
+		pr_err("Unable to locate active struct vhost_scsi_nexus\n");
+		return ERR_PTR(-EIO);
+	}
+
+	tag = sbitmap_get(&svq->scsi_tags);
+	if (tag < 0) {
+		pr_err("Unable to obtain tag for vhost_scsi_cmd\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	cmd = &svq->scsi_cmds[tag];
+	sg = cmd->tvc_sgl;
+	prot_sg = cmd->tvc_prot_sgl;
+	pages = cmd->tvc_upages;
+	tvc_resp_iov = cmd->tvc_resp_iov;
+	memset(cmd, 0, sizeof(*cmd));
+	cmd->tvc_sgl = sg;
+	cmd->tvc_prot_sgl = prot_sg;
+	cmd->tvc_upages = pages;
+	cmd->tvc_se_cmd.map_tag = tag;
+	cmd->tvc_tag = scsi_tag;
+	cmd->tvc_lun = lun;
+	cmd->tvc_task_attr = task_attr;
+	cmd->tvc_exp_data_len = exp_data_len;
+	cmd->tvc_data_direction = data_direction;
+	cmd->tvc_nexus = tv_nexus;
+	cmd->inflight = vhost_scsi_get_inflight(vq);
+	cmd->tvc_resp_iov = tvc_resp_iov;
+
+	memcpy(cmd->tvc_cdb, cdb, VHOST_SCSI_MAX_CDB_SIZE);
+
+	return cmd;
+}
+
+/*
+ * Map a user memory range into a scatterlist
+ *
+ * Returns the number of scatterlist entries used or -errno on error.
+ */
+static int
+vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
+		      struct iov_iter *iter,
+		      struct scatterlist *sgl,
+		      bool is_prot)
+{
+	struct page **pages = cmd->tvc_upages;
+	struct scatterlist *sg = sgl;
+	ssize_t bytes, mapped_bytes;
+	size_t offset, mapped_offset;
+	unsigned int npages = 0;
+
+	bytes = iov_iter_get_pages2(iter, pages, LONG_MAX,
+				VHOST_SCSI_PREALLOC_UPAGES, &offset);
+	/* No pages were pinned */
+	if (bytes <= 0)
+		return bytes < 0 ? bytes : -EFAULT;
+
+	mapped_bytes = bytes;
+	mapped_offset = offset;
+
+	while (bytes) {
+		unsigned n = min_t(unsigned, PAGE_SIZE - offset, bytes);
+		/*
+		 * The block layer requires bios/requests to be a multiple of
+		 * 512 bytes, but Windows can send us vecs that are misaligned.
+		 * This can result in bios and later requests with misaligned
+		 * sizes if we have to break up a cmd/scatterlist into multiple
+		 * bios.
+		 *
+		 * We currently only break up a command into multiple bios if
+		 * we hit the vec/seg limit, so check if our sgl_count is
+		 * greater than the max and if a vec in the cmd has a
+		 * misaligned offset/size.
+		 */
+		if (!is_prot &&
+		    (offset & (SECTOR_SIZE - 1) || n & (SECTOR_SIZE - 1)) &&
+		    cmd->tvc_sgl_count > BIO_MAX_VECS) {
+			WARN_ONCE(true,
+				  "vhost-scsi detected misaligned IO. Performance may be degraded.");
+			goto revert_iter_get_pages;
+		}
+
+		sg_set_page(sg++, pages[npages++], n, offset);
+		bytes -= n;
+		offset = 0;
+	}
+
+	return npages;
+
+revert_iter_get_pages:
+	iov_iter_revert(iter, mapped_bytes);
+
+	npages = 0;
+	while (mapped_bytes) {
+		unsigned int n = min_t(unsigned int, PAGE_SIZE - mapped_offset,
+				       mapped_bytes);
+
+		put_page(pages[npages++]);
+
+		mapped_bytes -= n;
+		mapped_offset = 0;
+	}
+
+	return -EINVAL;
+}
+
+static int
+vhost_scsi_calc_sgls(struct iov_iter *iter, size_t bytes, int max_sgls)
+{
+	int sgl_count = 0;
+
+	if (!iter || !iter_iov(iter)) {
+		pr_err("%s: iter->iov is NULL, but expected bytes: %zu"
+		       " present\n", __func__, bytes);
+		return -EINVAL;
+	}
+
+	sgl_count = iov_iter_npages(iter, 0xffff);
+	if (sgl_count > max_sgls) {
+		pr_err("%s: requested sgl_count: %d exceeds pre-allocated"
+		       " max_sgls: %d\n", __func__, sgl_count, max_sgls);
+		return -EINVAL;
+	}
+	return sgl_count;
+}
+
+static int
+vhost_scsi_copy_iov_to_sgl(struct vhost_scsi_cmd *cmd, struct iov_iter *iter,
+			   struct scatterlist *sg, int sg_count)
+{
+	size_t len = iov_iter_count(iter);
+	unsigned int nbytes = 0;
+	struct page *page;
+	int i;
+
+	if (cmd->tvc_data_direction == DMA_FROM_DEVICE) {
+		cmd->saved_iter_addr = dup_iter(&cmd->saved_iter, iter,
+						GFP_KERNEL);
+		if (!cmd->saved_iter_addr)
+			return -ENOMEM;
+	}
+
+	for (i = 0; i < sg_count; i++) {
+		page = alloc_page(GFP_KERNEL);
+		if (!page) {
+			i--;
+			goto err;
+		}
+
+		nbytes = min_t(unsigned int, PAGE_SIZE, len);
+		sg_set_page(&sg[i], page, nbytes, 0);
+
+		if (cmd->tvc_data_direction == DMA_TO_DEVICE &&
+		    copy_page_from_iter(page, 0, nbytes, iter) != nbytes)
+			goto err;
+
+		len -= nbytes;
+	}
+
+	cmd->copied_iov = 1;
+	return 0;
+
+err:
+	pr_err("Could not read %u bytes while handling misaligned cmd\n",
+	       nbytes);
+
+	for (; i >= 0; i--)
+		__free_page(sg_page(&sg[i]));
+	kfree(cmd->saved_iter_addr);
+	return -ENOMEM;
+}
+
+static int
+vhost_scsi_map_iov_to_sgl(struct vhost_scsi_cmd *cmd, struct iov_iter *iter,
+			  struct scatterlist *sg, int sg_count, bool is_prot)
+{
+	struct scatterlist *p = sg;
+	size_t revert_bytes;
+	int ret;
+
+	while (iov_iter_count(iter)) {
+		ret = vhost_scsi_map_to_sgl(cmd, iter, sg, is_prot);
+		if (ret < 0) {
+			revert_bytes = 0;
+
+			while (p < sg) {
+				struct page *page = sg_page(p);
+
+				if (page) {
+					put_page(page);
+					revert_bytes += p->length;
+				}
+				p++;
+			}
+
+			iov_iter_revert(iter, revert_bytes);
+			return ret;
+		}
+		sg += ret;
+	}
+
+	return 0;
+}
+
+static int
+vhost_scsi_mapal(struct vhost_scsi_cmd *cmd,
+		 size_t prot_bytes, struct iov_iter *prot_iter,
+		 size_t data_bytes, struct iov_iter *data_iter)
+{
+	int sgl_count, ret;
+
+	if (prot_bytes) {
+		sgl_count = vhost_scsi_calc_sgls(prot_iter, prot_bytes,
+						 VHOST_SCSI_PREALLOC_PROT_SGLS);
+		if (sgl_count < 0)
+			return sgl_count;
+
+		sg_init_table(cmd->tvc_prot_sgl, sgl_count);
+		cmd->tvc_prot_sgl_count = sgl_count;
+		pr_debug("%s prot_sg %p prot_sgl_count %u\n", __func__,
+			 cmd->tvc_prot_sgl, cmd->tvc_prot_sgl_count);
+
+		ret = vhost_scsi_map_iov_to_sgl(cmd, prot_iter,
+						cmd->tvc_prot_sgl,
+						cmd->tvc_prot_sgl_count, true);
+		if (ret < 0) {
+			cmd->tvc_prot_sgl_count = 0;
+			return ret;
+		}
+	}
+	sgl_count = vhost_scsi_calc_sgls(data_iter, data_bytes,
+					 VHOST_SCSI_PREALLOC_SGLS);
+	if (sgl_count < 0)
+		return sgl_count;
+
+	sg_init_table(cmd->tvc_sgl, sgl_count);
+	cmd->tvc_sgl_count = sgl_count;
+	pr_debug("%s data_sg %p data_sgl_count %u\n", __func__,
+		  cmd->tvc_sgl, cmd->tvc_sgl_count);
+
+	ret = vhost_scsi_map_iov_to_sgl(cmd, data_iter, cmd->tvc_sgl,
+					cmd->tvc_sgl_count, false);
+	if (ret == -EINVAL) {
+		sg_init_table(cmd->tvc_sgl, cmd->tvc_sgl_count);
+		ret = vhost_scsi_copy_iov_to_sgl(cmd, data_iter, cmd->tvc_sgl,
+						 cmd->tvc_sgl_count);
+	}
+
+	if (ret < 0) {
+		cmd->tvc_sgl_count = 0;
+		return ret;
+	}
+	return 0;
+}
+
+static int vhost_scsi_to_tcm_attr(int attr)
+{
+	switch (attr) {
+	case VIRTIO_SCSI_S_SIMPLE:
+		return TCM_SIMPLE_TAG;
+	case VIRTIO_SCSI_S_ORDERED:
+		return TCM_ORDERED_TAG;
+	case VIRTIO_SCSI_S_HEAD:
+		return TCM_HEAD_TAG;
+	case VIRTIO_SCSI_S_ACA:
+		return TCM_ACA_TAG;
+	default:
+		break;
+	}
+	return TCM_SIMPLE_TAG;
+}
+
+static void vhost_scsi_target_queue_cmd(struct vhost_scsi_cmd *cmd)
+{
+	struct se_cmd *se_cmd = &cmd->tvc_se_cmd;
+	struct vhost_scsi_nexus *tv_nexus;
+	struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
+
+	/* FIXME: BIDI operation */
+	if (cmd->tvc_sgl_count) {
+		sg_ptr = cmd->tvc_sgl;
+
+		if (cmd->tvc_prot_sgl_count)
+			sg_prot_ptr = cmd->tvc_prot_sgl;
+		else
+			se_cmd->prot_pto = true;
+	} else {
+		sg_ptr = NULL;
+	}
+	tv_nexus = cmd->tvc_nexus;
+
+	se_cmd->tag = 0;
+	target_init_cmd(se_cmd, tv_nexus->tvn_se_sess, &cmd->tvc_sense_buf[0],
+			cmd->tvc_lun, cmd->tvc_exp_data_len,
+			vhost_scsi_to_tcm_attr(cmd->tvc_task_attr),
+			cmd->tvc_data_direction, TARGET_SCF_ACK_KREF);
+
+	if (target_submit_prep(se_cmd, cmd->tvc_cdb, sg_ptr,
+			       cmd->tvc_sgl_count, NULL, 0, sg_prot_ptr,
+			       cmd->tvc_prot_sgl_count, GFP_KERNEL))
+		return;
+
+	target_queue_submission(se_cmd);
+}
+
+static void
+vhost_scsi_send_bad_target(struct vhost_scsi *vs,
+			   struct vhost_virtqueue *vq,
+			   int head, unsigned out)
+{
+	struct virtio_scsi_cmd_resp __user *resp;
+	struct virtio_scsi_cmd_resp rsp;
+	int ret;
+
+	memset(&rsp, 0, sizeof(rsp));
+	rsp.response = VIRTIO_SCSI_S_BAD_TARGET;
+	resp = vq->iov[out].iov_base;
+	ret = __copy_to_user(resp, &rsp, sizeof(rsp));
+	if (!ret)
+		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+	else
+		pr_err("Faulted on virtio_scsi_cmd_resp\n");
+}
+
+static int
+vhost_scsi_get_desc(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
+		    struct vhost_scsi_ctx *vc)
+{
+	int ret = -ENXIO;
+
+	vc->head = vhost_get_vq_desc(vq, vq->iov,
+				     ARRAY_SIZE(vq->iov), &vc->out, &vc->in,
+				     NULL, NULL);
+
+	pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
+		 vc->head, vc->out, vc->in);
+
+	/* On error, stop handling until the next kick. */
+	if (unlikely(vc->head < 0))
+		goto done;
+
+	/* Nothing new?  Wait for eventfd to tell us they refilled. */
+	if (vc->head == vq->num) {
+		if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
+			vhost_disable_notify(&vs->dev, vq);
+			ret = -EAGAIN;
+		}
+		goto done;
+	}
+
+	/*
+	 * Get the size of request and response buffers.
+	 * FIXME: Not correct for BIDI operation
+	 */
+	vc->out_size = iov_length(vq->iov, vc->out);
+	vc->in_size = iov_length(&vq->iov[vc->out], vc->in);
+
+	/*
+	 * Copy over the virtio-scsi request header, which for a
+	 * ANY_LAYOUT enabled guest may span multiple iovecs, or a
+	 * single iovec may contain both the header + outgoing
+	 * WRITE payloads.
+	 *
+	 * copy_from_iter() will advance out_iter, so that it will
+	 * point at the start of the outgoing WRITE payload, if
+	 * DMA_TO_DEVICE is set.
+	 */
+	iov_iter_init(&vc->out_iter, ITER_SOURCE, vq->iov, vc->out, vc->out_size);
+	ret = 0;
+
+done:
+	return ret;
+}
+
+static int
+vhost_scsi_chk_size(struct vhost_virtqueue *vq, struct vhost_scsi_ctx *vc)
+{
+	if (unlikely(vc->in_size < vc->rsp_size)) {
+		vq_err(vq,
+		       "Response buf too small, need min %zu bytes got %zu",
+		       vc->rsp_size, vc->in_size);
+		return -EINVAL;
+	} else if (unlikely(vc->out_size < vc->req_size)) {
+		vq_err(vq,
+		       "Request buf too small, need min %zu bytes got %zu",
+		       vc->req_size, vc->out_size);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int
+vhost_scsi_get_req(struct vhost_virtqueue *vq, struct vhost_scsi_ctx *vc,
+		   struct vhost_scsi_tpg **tpgp)
+{
+	int ret = -EIO;
+
+	if (unlikely(!copy_from_iter_full(vc->req, vc->req_size,
+					  &vc->out_iter))) {
+		vq_err(vq, "Faulted on copy_from_iter_full\n");
+	} else if (unlikely(*vc->lunp != 1)) {
+		/* virtio-scsi spec requires byte 0 of the lun to be 1 */
+		vq_err(vq, "Illegal virtio-scsi lun: %u\n", *vc->lunp);
+	} else {
+		struct vhost_scsi_tpg **vs_tpg, *tpg;
+
+		vs_tpg = vhost_vq_get_backend(vq);	/* validated at handler entry */
+
+		tpg = READ_ONCE(vs_tpg[*vc->target]);
+		if (unlikely(!tpg)) {
+			vq_err(vq, "Target 0x%x does not exist\n", *vc->target);
+		} else {
+			if (tpgp)
+				*tpgp = tpg;
+			ret = 0;
+		}
+	}
+
+	return ret;
+}
+
+static u16 vhost_buf_to_lun(u8 *lun_buf)
+{
+	return ((lun_buf[2] << 8) | lun_buf[3]) & 0x3FFF;
+}
+
+static void
+vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
+{
+	struct vhost_scsi_tpg **vs_tpg, *tpg;
+	struct virtio_scsi_cmd_req v_req;
+	struct virtio_scsi_cmd_req_pi v_req_pi;
+	struct vhost_scsi_ctx vc;
+	struct vhost_scsi_cmd *cmd;
+	struct iov_iter in_iter, prot_iter, data_iter;
+	u64 tag;
+	u32 exp_data_len, data_direction;
+	int ret, prot_bytes, i, c = 0;
+	u16 lun;
+	u8 task_attr;
+	bool t10_pi = vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI);
+	void *cdb;
+
+	mutex_lock(&vq->mutex);
+	/*
+	 * We can handle the vq only after the endpoint is setup by calling the
+	 * VHOST_SCSI_SET_ENDPOINT ioctl.
+	 */
+	vs_tpg = vhost_vq_get_backend(vq);
+	if (!vs_tpg)
+		goto out;
+
+	memset(&vc, 0, sizeof(vc));
+	vc.rsp_size = sizeof(struct virtio_scsi_cmd_resp);
+
+	vhost_disable_notify(&vs->dev, vq);
+
+	do {
+		ret = vhost_scsi_get_desc(vs, vq, &vc);
+		if (ret)
+			goto err;
+
+		/*
+		 * Setup pointers and values based upon different virtio-scsi
+		 * request header if T10_PI is enabled in KVM guest.
+		 */
+		if (t10_pi) {
+			vc.req = &v_req_pi;
+			vc.req_size = sizeof(v_req_pi);
+			vc.lunp = &v_req_pi.lun[0];
+			vc.target = &v_req_pi.lun[1];
+		} else {
+			vc.req = &v_req;
+			vc.req_size = sizeof(v_req);
+			vc.lunp = &v_req.lun[0];
+			vc.target = &v_req.lun[1];
+		}
+
+		/*
+		 * Validate the size of request and response buffers.
+		 * Check for a sane response buffer so we can report
+		 * early errors back to the guest.
+		 */
+		ret = vhost_scsi_chk_size(vq, &vc);
+		if (ret)
+			goto err;
+
+		ret = vhost_scsi_get_req(vq, &vc, &tpg);
+		if (ret)
+			goto err;
+
+		ret = -EIO;	/* bad target on any error from here on */
+
+		/*
+		 * Determine data_direction by calculating the total outgoing
+		 * iovec sizes + incoming iovec sizes vs. virtio-scsi request +
+		 * response headers respectively.
+		 *
+		 * For DMA_TO_DEVICE this is out_iter, which is already pointing
+		 * to the right place.
+		 *
+		 * For DMA_FROM_DEVICE, the iovec will be just past the end
+		 * of the virtio-scsi response header in either the same
+		 * or immediately following iovec.
+		 *
+		 * Any associated T10_PI bytes for the outgoing / incoming
+		 * payloads are included in calculation of exp_data_len here.
+		 */
+		prot_bytes = 0;
+
+		if (vc.out_size > vc.req_size) {
+			data_direction = DMA_TO_DEVICE;
+			exp_data_len = vc.out_size - vc.req_size;
+			data_iter = vc.out_iter;
+		} else if (vc.in_size > vc.rsp_size) {
+			data_direction = DMA_FROM_DEVICE;
+			exp_data_len = vc.in_size - vc.rsp_size;
+
+			iov_iter_init(&in_iter, ITER_DEST, &vq->iov[vc.out], vc.in,
+				      vc.rsp_size + exp_data_len);
+			iov_iter_advance(&in_iter, vc.rsp_size);
+			data_iter = in_iter;
+		} else {
+			data_direction = DMA_NONE;
+			exp_data_len = 0;
+		}
+		/*
+		 * If T10_PI header + payload is present, setup prot_iter values
+		 * and recalculate data_iter for vhost_scsi_mapal() mapping to
+		 * host scatterlists via get_user_pages_fast().
+		 */
+		if (t10_pi) {
+			if (v_req_pi.pi_bytesout) {
+				if (data_direction != DMA_TO_DEVICE) {
+					vq_err(vq, "Received non zero pi_bytesout,"
+						" but wrong data_direction\n");
+					goto err;
+				}
+				prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesout);
+			} else if (v_req_pi.pi_bytesin) {
+				if (data_direction != DMA_FROM_DEVICE) {
+					vq_err(vq, "Received non zero pi_bytesin,"
+						" but wrong data_direction\n");
+					goto err;
+				}
+				prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
+			}
+			/*
+			 * Set prot_iter to data_iter and truncate it to
+			 * prot_bytes, and advance data_iter past any
+			 * preceeding prot_bytes that may be present.
+			 *
+			 * Also fix up the exp_data_len to reflect only the
+			 * actual data payload length.
+			 */
+			if (prot_bytes) {
+				exp_data_len -= prot_bytes;
+				prot_iter = data_iter;
+				iov_iter_truncate(&prot_iter, prot_bytes);
+				iov_iter_advance(&data_iter, prot_bytes);
+			}
+			tag = vhost64_to_cpu(vq, v_req_pi.tag);
+			task_attr = v_req_pi.task_attr;
+			cdb = &v_req_pi.cdb[0];
+			lun = vhost_buf_to_lun(v_req_pi.lun);
+		} else {
+			tag = vhost64_to_cpu(vq, v_req.tag);
+			task_attr = v_req.task_attr;
+			cdb = &v_req.cdb[0];
+			lun = vhost_buf_to_lun(v_req.lun);
+		}
+		/*
+		 * Check that the received CDB size does not exceeded our
+		 * hardcoded max for vhost-scsi, then get a pre-allocated
+		 * cmd descriptor for the new virtio-scsi tag.
+		 *
+		 * TODO what if cdb was too small for varlen cdb header?
+		 */
+		if (unlikely(scsi_command_size(cdb) > VHOST_SCSI_MAX_CDB_SIZE)) {
+			vq_err(vq, "Received SCSI CDB with command_size: %d that"
+				" exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
+				scsi_command_size(cdb), VHOST_SCSI_MAX_CDB_SIZE);
+				goto err;
+		}
+		cmd = vhost_scsi_get_cmd(vq, tpg, cdb, tag, lun, task_attr,
+					 exp_data_len + prot_bytes,
+					 data_direction);
+		if (IS_ERR(cmd)) {
+			vq_err(vq, "vhost_scsi_get_cmd failed %ld\n",
+			       PTR_ERR(cmd));
+			goto err;
+		}
+		cmd->tvc_vhost = vs;
+		cmd->tvc_vq = vq;
+		for (i = 0; i < vc.in ; i++)
+			cmd->tvc_resp_iov[i] = vq->iov[vc.out + i];
+		cmd->tvc_in_iovs = vc.in;
+
+		pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
+			 cmd->tvc_cdb[0], cmd->tvc_lun);
+		pr_debug("cmd: %p exp_data_len: %d, prot_bytes: %d data_direction:"
+			 " %d\n", cmd, exp_data_len, prot_bytes, data_direction);
+
+		if (data_direction != DMA_NONE) {
+			if (unlikely(vhost_scsi_mapal(cmd, prot_bytes,
+						      &prot_iter, exp_data_len,
+						      &data_iter))) {
+				vq_err(vq, "Failed to map iov to sgl\n");
+				vhost_scsi_release_cmd_res(&cmd->tvc_se_cmd);
+				goto err;
+			}
+		}
+		/*
+		 * Save the descriptor from vhost_get_vq_desc() to be used to
+		 * complete the virtio-scsi request in TCM callback context via
+		 * vhost_scsi_queue_data_in() and vhost_scsi_queue_status()
+		 */
+		cmd->tvc_vq_desc = vc.head;
+		vhost_scsi_target_queue_cmd(cmd);
+		ret = 0;
+err:
+		/*
+		 * ENXIO:  No more requests, or read error, wait for next kick
+		 * EINVAL: Invalid response buffer, drop the request
+		 * EIO:    Respond with bad target
+		 * EAGAIN: Pending request
+		 */
+		if (ret == -ENXIO)
+			break;
+		else if (ret == -EIO)
+			vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out);
+	} while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static void
+vhost_scsi_send_tmf_resp(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
+			 int in_iovs, int vq_desc, struct iovec *resp_iov,
+			 int tmf_resp_code)
+{
+	struct virtio_scsi_ctrl_tmf_resp rsp;
+	struct iov_iter iov_iter;
+	int ret;
+
+	pr_debug("%s\n", __func__);
+	memset(&rsp, 0, sizeof(rsp));
+	rsp.response = tmf_resp_code;
+
+	iov_iter_init(&iov_iter, ITER_DEST, resp_iov, in_iovs, sizeof(rsp));
+
+	ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
+	if (likely(ret == sizeof(rsp)))
+		vhost_add_used_and_signal(&vs->dev, vq, vq_desc, 0);
+	else
+		pr_err("Faulted on virtio_scsi_ctrl_tmf_resp\n");
+}
+
+static void vhost_scsi_tmf_resp_work(struct vhost_work *work)
+{
+	struct vhost_scsi_tmf *tmf = container_of(work, struct vhost_scsi_tmf,
+						  vwork);
+	struct vhost_virtqueue *ctl_vq, *vq;
+	int resp_code, i;
+
+	if (tmf->scsi_resp == TMR_FUNCTION_COMPLETE) {
+		/*
+		 * Flush IO vqs that don't share a worker with the ctl to make
+		 * sure they have sent their responses before us.
+		 */
+		ctl_vq = &tmf->vhost->vqs[VHOST_SCSI_VQ_CTL].vq;
+		for (i = VHOST_SCSI_VQ_IO; i < tmf->vhost->dev.nvqs; i++) {
+			vq = &tmf->vhost->vqs[i].vq;
+
+			if (vhost_vq_is_setup(vq) &&
+			    vq->worker != ctl_vq->worker)
+				vhost_vq_flush(vq);
+		}
+
+		resp_code = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+	} else {
+		resp_code = VIRTIO_SCSI_S_FUNCTION_REJECTED;
+	}
+
+	vhost_scsi_send_tmf_resp(tmf->vhost, &tmf->svq->vq, tmf->in_iovs,
+				 tmf->vq_desc, &tmf->resp_iov, resp_code);
+	vhost_scsi_release_tmf_res(tmf);
+}
+
+static void
+vhost_scsi_handle_tmf(struct vhost_scsi *vs, struct vhost_scsi_tpg *tpg,
+		      struct vhost_virtqueue *vq,
+		      struct virtio_scsi_ctrl_tmf_req *vtmf,
+		      struct vhost_scsi_ctx *vc)
+{
+	struct vhost_scsi_virtqueue *svq = container_of(vq,
+					struct vhost_scsi_virtqueue, vq);
+	struct vhost_scsi_tmf *tmf;
+
+	if (vhost32_to_cpu(vq, vtmf->subtype) !=
+	    VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET)
+		goto send_reject;
+
+	if (!tpg->tpg_nexus || !tpg->tpg_nexus->tvn_se_sess) {
+		pr_err("Unable to locate active struct vhost_scsi_nexus for LUN RESET.\n");
+		goto send_reject;
+	}
+
+	tmf = kzalloc(sizeof(*tmf), GFP_KERNEL);
+	if (!tmf)
+		goto send_reject;
+
+	vhost_work_init(&tmf->vwork, vhost_scsi_tmf_resp_work);
+	tmf->vhost = vs;
+	tmf->svq = svq;
+	tmf->resp_iov = vq->iov[vc->out];
+	tmf->vq_desc = vc->head;
+	tmf->in_iovs = vc->in;
+	tmf->inflight = vhost_scsi_get_inflight(vq);
+
+	if (target_submit_tmr(&tmf->se_cmd, tpg->tpg_nexus->tvn_se_sess, NULL,
+			      vhost_buf_to_lun(vtmf->lun), NULL,
+			      TMR_LUN_RESET, GFP_KERNEL, 0,
+			      TARGET_SCF_ACK_KREF) < 0) {
+		vhost_scsi_release_tmf_res(tmf);
+		goto send_reject;
+	}
+
+	return;
+
+send_reject:
+	vhost_scsi_send_tmf_resp(vs, vq, vc->in, vc->head, &vq->iov[vc->out],
+				 VIRTIO_SCSI_S_FUNCTION_REJECTED);
+}
+
+static void
+vhost_scsi_send_an_resp(struct vhost_scsi *vs,
+			struct vhost_virtqueue *vq,
+			struct vhost_scsi_ctx *vc)
+{
+	struct virtio_scsi_ctrl_an_resp rsp;
+	struct iov_iter iov_iter;
+	int ret;
+
+	pr_debug("%s\n", __func__);
+	memset(&rsp, 0, sizeof(rsp));	/* event_actual = 0 */
+	rsp.response = VIRTIO_SCSI_S_OK;
+
+	iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[vc->out], vc->in, sizeof(rsp));
+
+	ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
+	if (likely(ret == sizeof(rsp)))
+		vhost_add_used_and_signal(&vs->dev, vq, vc->head, 0);
+	else
+		pr_err("Faulted on virtio_scsi_ctrl_an_resp\n");
+}
+
+static void
+vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
+{
+	struct vhost_scsi_tpg *tpg;
+	union {
+		__virtio32 type;
+		struct virtio_scsi_ctrl_an_req an;
+		struct virtio_scsi_ctrl_tmf_req tmf;
+	} v_req;
+	struct vhost_scsi_ctx vc;
+	size_t typ_size;
+	int ret, c = 0;
+
+	mutex_lock(&vq->mutex);
+	/*
+	 * We can handle the vq only after the endpoint is setup by calling the
+	 * VHOST_SCSI_SET_ENDPOINT ioctl.
+	 */
+	if (!vhost_vq_get_backend(vq))
+		goto out;
+
+	memset(&vc, 0, sizeof(vc));
+
+	vhost_disable_notify(&vs->dev, vq);
+
+	do {
+		ret = vhost_scsi_get_desc(vs, vq, &vc);
+		if (ret)
+			goto err;
+
+		/*
+		 * Get the request type first in order to setup
+		 * other parameters dependent on the type.
+		 */
+		vc.req = &v_req.type;
+		typ_size = sizeof(v_req.type);
+
+		if (unlikely(!copy_from_iter_full(vc.req, typ_size,
+						  &vc.out_iter))) {
+			vq_err(vq, "Faulted on copy_from_iter tmf type\n");
+			/*
+			 * The size of the response buffer depends on the
+			 * request type and must be validated against it.
+			 * Since the request type is not known, don't send
+			 * a response.
+			 */
+			continue;
+		}
+
+		switch (vhost32_to_cpu(vq, v_req.type)) {
+		case VIRTIO_SCSI_T_TMF:
+			vc.req = &v_req.tmf;
+			vc.req_size = sizeof(struct virtio_scsi_ctrl_tmf_req);
+			vc.rsp_size = sizeof(struct virtio_scsi_ctrl_tmf_resp);
+			vc.lunp = &v_req.tmf.lun[0];
+			vc.target = &v_req.tmf.lun[1];
+			break;
+		case VIRTIO_SCSI_T_AN_QUERY:
+		case VIRTIO_SCSI_T_AN_SUBSCRIBE:
+			vc.req = &v_req.an;
+			vc.req_size = sizeof(struct virtio_scsi_ctrl_an_req);
+			vc.rsp_size = sizeof(struct virtio_scsi_ctrl_an_resp);
+			vc.lunp = &v_req.an.lun[0];
+			vc.target = NULL;
+			break;
+		default:
+			vq_err(vq, "Unknown control request %d", v_req.type);
+			continue;
+		}
+
+		/*
+		 * Validate the size of request and response buffers.
+		 * Check for a sane response buffer so we can report
+		 * early errors back to the guest.
+		 */
+		ret = vhost_scsi_chk_size(vq, &vc);
+		if (ret)
+			goto err;
+
+		/*
+		 * Get the rest of the request now that its size is known.
+		 */
+		vc.req += typ_size;
+		vc.req_size -= typ_size;
+
+		ret = vhost_scsi_get_req(vq, &vc, &tpg);
+		if (ret)
+			goto err;
+
+		if (v_req.type == VIRTIO_SCSI_T_TMF)
+			vhost_scsi_handle_tmf(vs, tpg, vq, &v_req.tmf, &vc);
+		else
+			vhost_scsi_send_an_resp(vs, vq, &vc);
+err:
+		/*
+		 * ENXIO:  No more requests, or read error, wait for next kick
+		 * EINVAL: Invalid response buffer, drop the request
+		 * EIO:    Respond with bad target
+		 * EAGAIN: Pending request
+		 */
+		if (ret == -ENXIO)
+			break;
+		else if (ret == -EIO)
+			vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out);
+	} while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						poll.work);
+	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
+
+	pr_debug("%s: The handling func for control queue.\n", __func__);
+	vhost_scsi_ctl_handle_vq(vs, vq);
+}
+
+static void
+vhost_scsi_send_evt(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
+		    struct vhost_scsi_tpg *tpg, struct se_lun *lun,
+		    u32 event, u32 reason)
+{
+	struct vhost_scsi_evt *evt;
+
+	evt = vhost_scsi_allocate_evt(vs, event, reason);
+	if (!evt)
+		return;
+
+	if (tpg && lun) {
+		/* TODO: share lun setup code with virtio-scsi.ko */
+		/*
+		 * Note: evt->event is zeroed when we allocate it and
+		 * lun[4-7] need to be zero according to virtio-scsi spec.
+		 */
+		evt->event.lun[0] = 0x01;
+		evt->event.lun[1] = tpg->tport_tpgt;
+		if (lun->unpacked_lun >= 256)
+			evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
+		evt->event.lun[3] = lun->unpacked_lun & 0xFF;
+	}
+
+	llist_add(&evt->list, &vs->vs_event_list);
+	vhost_vq_work_queue(vq, &vs->vs_event_work);
+}
+
+static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						poll.work);
+	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
+
+	mutex_lock(&vq->mutex);
+	if (!vhost_vq_get_backend(vq))
+		goto out;
+
+	if (vs->vs_events_missed)
+		vhost_scsi_send_evt(vs, vq, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT,
+				    0);
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static void vhost_scsi_handle_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						poll.work);
+	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
+
+	vhost_scsi_handle_vq(vs, vq);
+}
+
+/* Callers must hold dev mutex */
+static void vhost_scsi_flush(struct vhost_scsi *vs)
+{
+	int i;
+
+	/* Init new inflight and remember the old inflight */
+	vhost_scsi_init_inflight(vs, vs->old_inflight);
+
+	/*
+	 * The inflight->kref was initialized to 1. We decrement it here to
+	 * indicate the start of the flush operation so that it will reach 0
+	 * when all the reqs are finished.
+	 */
+	for (i = 0; i < vs->dev.nvqs; i++)
+		kref_put(&vs->old_inflight[i]->kref, vhost_scsi_done_inflight);
+
+	/* Flush both the vhost poll and vhost work */
+	vhost_dev_flush(&vs->dev);
+
+	/* Wait for all reqs issued before the flush to be finished */
+	for (i = 0; i < vs->dev.nvqs; i++)
+		wait_for_completion(&vs->old_inflight[i]->comp);
+}
+
+static void vhost_scsi_destroy_vq_cmds(struct vhost_virtqueue *vq)
+{
+	struct vhost_scsi_virtqueue *svq = container_of(vq,
+					struct vhost_scsi_virtqueue, vq);
+	struct vhost_scsi_cmd *tv_cmd;
+	unsigned int i;
+
+	if (!svq->scsi_cmds)
+		return;
+
+	for (i = 0; i < svq->max_cmds; i++) {
+		tv_cmd = &svq->scsi_cmds[i];
+
+		kfree(tv_cmd->tvc_sgl);
+		kfree(tv_cmd->tvc_prot_sgl);
+		kfree(tv_cmd->tvc_upages);
+		kfree(tv_cmd->tvc_resp_iov);
+	}
+
+	sbitmap_free(&svq->scsi_tags);
+	kfree(svq->scsi_cmds);
+	svq->scsi_cmds = NULL;
+}
+
+static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds)
+{
+	struct vhost_scsi_virtqueue *svq = container_of(vq,
+					struct vhost_scsi_virtqueue, vq);
+	struct vhost_scsi_cmd *tv_cmd;
+	unsigned int i;
+
+	if (svq->scsi_cmds)
+		return 0;
+
+	if (sbitmap_init_node(&svq->scsi_tags, max_cmds, -1, GFP_KERNEL,
+			      NUMA_NO_NODE, false, true))
+		return -ENOMEM;
+	svq->max_cmds = max_cmds;
+
+	svq->scsi_cmds = kcalloc(max_cmds, sizeof(*tv_cmd), GFP_KERNEL);
+	if (!svq->scsi_cmds) {
+		sbitmap_free(&svq->scsi_tags);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < max_cmds; i++) {
+		tv_cmd = &svq->scsi_cmds[i];
+
+		tv_cmd->tvc_sgl = kcalloc(VHOST_SCSI_PREALLOC_SGLS,
+					  sizeof(struct scatterlist),
+					  GFP_KERNEL);
+		if (!tv_cmd->tvc_sgl) {
+			pr_err("Unable to allocate tv_cmd->tvc_sgl\n");
+			goto out;
+		}
+
+		tv_cmd->tvc_upages = kcalloc(VHOST_SCSI_PREALLOC_UPAGES,
+					     sizeof(struct page *),
+					     GFP_KERNEL);
+		if (!tv_cmd->tvc_upages) {
+			pr_err("Unable to allocate tv_cmd->tvc_upages\n");
+			goto out;
+		}
+
+		tv_cmd->tvc_resp_iov = kcalloc(UIO_MAXIOV,
+					       sizeof(struct iovec),
+					       GFP_KERNEL);
+		if (!tv_cmd->tvc_resp_iov) {
+			pr_err("Unable to allocate tv_cmd->tvc_resp_iov\n");
+			goto out;
+		}
+
+		tv_cmd->tvc_prot_sgl = kcalloc(VHOST_SCSI_PREALLOC_PROT_SGLS,
+					       sizeof(struct scatterlist),
+					       GFP_KERNEL);
+		if (!tv_cmd->tvc_prot_sgl) {
+			pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n");
+			goto out;
+		}
+	}
+	return 0;
+out:
+	vhost_scsi_destroy_vq_cmds(vq);
+	return -ENOMEM;
+}
+
+/*
+ * Called from vhost_scsi_ioctl() context to walk the list of available
+ * vhost_scsi_tpg with an active struct vhost_scsi_nexus
+ *
+ *  The lock nesting rule is:
+ *    vs->dev.mutex -> vhost_scsi_mutex -> tpg->tv_tpg_mutex -> vq->mutex
+ */
+static int
+vhost_scsi_set_endpoint(struct vhost_scsi *vs,
+			struct vhost_scsi_target *t)
+{
+	struct se_portal_group *se_tpg;
+	struct vhost_scsi_tport *tv_tport;
+	struct vhost_scsi_tpg *tpg;
+	struct vhost_scsi_tpg **vs_tpg;
+	struct vhost_virtqueue *vq;
+	int index, ret, i, len;
+	bool match = false;
+
+	mutex_lock(&vs->dev.mutex);
+
+	/* Verify that ring has been setup correctly. */
+	for (index = 0; index < vs->dev.nvqs; ++index) {
+		/* Verify that ring has been setup correctly. */
+		if (!vhost_vq_access_ok(&vs->vqs[index].vq)) {
+			ret = -EFAULT;
+			goto out;
+		}
+	}
+
+	len = sizeof(vs_tpg[0]) * VHOST_SCSI_MAX_TARGET;
+	vs_tpg = kzalloc(len, GFP_KERNEL);
+	if (!vs_tpg) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	if (vs->vs_tpg)
+		memcpy(vs_tpg, vs->vs_tpg, len);
+
+	mutex_lock(&vhost_scsi_mutex);
+	list_for_each_entry(tpg, &vhost_scsi_list, tv_tpg_list) {
+		mutex_lock(&tpg->tv_tpg_mutex);
+		if (!tpg->tpg_nexus) {
+			mutex_unlock(&tpg->tv_tpg_mutex);
+			continue;
+		}
+		if (tpg->tv_tpg_vhost_count != 0) {
+			mutex_unlock(&tpg->tv_tpg_mutex);
+			continue;
+		}
+		tv_tport = tpg->tport;
+
+		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
+			if (vs->vs_tpg && vs->vs_tpg[tpg->tport_tpgt]) {
+				mutex_unlock(&tpg->tv_tpg_mutex);
+				mutex_unlock(&vhost_scsi_mutex);
+				ret = -EEXIST;
+				goto undepend;
+			}
+			/*
+			 * In order to ensure individual vhost-scsi configfs
+			 * groups cannot be removed while in use by vhost ioctl,
+			 * go ahead and take an explicit se_tpg->tpg_group.cg_item
+			 * dependency now.
+			 */
+			se_tpg = &tpg->se_tpg;
+			ret = target_depend_item(&se_tpg->tpg_group.cg_item);
+			if (ret) {
+				pr_warn("target_depend_item() failed: %d\n", ret);
+				mutex_unlock(&tpg->tv_tpg_mutex);
+				mutex_unlock(&vhost_scsi_mutex);
+				goto undepend;
+			}
+			tpg->tv_tpg_vhost_count++;
+			tpg->vhost_scsi = vs;
+			vs_tpg[tpg->tport_tpgt] = tpg;
+			match = true;
+		}
+		mutex_unlock(&tpg->tv_tpg_mutex);
+	}
+	mutex_unlock(&vhost_scsi_mutex);
+
+	if (match) {
+		memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
+		       sizeof(vs->vs_vhost_wwpn));
+
+		for (i = VHOST_SCSI_VQ_IO; i < vs->dev.nvqs; i++) {
+			vq = &vs->vqs[i].vq;
+			if (!vhost_vq_is_setup(vq))
+				continue;
+
+			ret = vhost_scsi_setup_vq_cmds(vq, vq->num);
+			if (ret)
+				goto destroy_vq_cmds;
+		}
+
+		for (i = 0; i < vs->dev.nvqs; i++) {
+			vq = &vs->vqs[i].vq;
+			mutex_lock(&vq->mutex);
+			vhost_vq_set_backend(vq, vs_tpg);
+			vhost_vq_init_access(vq);
+			mutex_unlock(&vq->mutex);
+		}
+		ret = 0;
+	} else {
+		ret = -EEXIST;
+	}
+
+	/*
+	 * Act as synchronize_rcu to make sure access to
+	 * old vs->vs_tpg is finished.
+	 */
+	vhost_scsi_flush(vs);
+	kfree(vs->vs_tpg);
+	vs->vs_tpg = vs_tpg;
+	goto out;
+
+destroy_vq_cmds:
+	for (i--; i >= VHOST_SCSI_VQ_IO; i--) {
+		if (!vhost_vq_get_backend(&vs->vqs[i].vq))
+			vhost_scsi_destroy_vq_cmds(&vs->vqs[i].vq);
+	}
+undepend:
+	for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
+		tpg = vs_tpg[i];
+		if (tpg) {
+			mutex_lock(&tpg->tv_tpg_mutex);
+			tpg->vhost_scsi = NULL;
+			tpg->tv_tpg_vhost_count--;
+			mutex_unlock(&tpg->tv_tpg_mutex);
+			target_undepend_item(&tpg->se_tpg.tpg_group.cg_item);
+		}
+	}
+	kfree(vs_tpg);
+out:
+	mutex_unlock(&vs->dev.mutex);
+	return ret;
+}
+
+static int
+vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
+			  struct vhost_scsi_target *t)
+{
+	struct se_portal_group *se_tpg;
+	struct vhost_scsi_tport *tv_tport;
+	struct vhost_scsi_tpg *tpg;
+	struct vhost_virtqueue *vq;
+	bool match = false;
+	int index, ret, i;
+	u8 target;
+
+	mutex_lock(&vs->dev.mutex);
+	/* Verify that ring has been setup correctly. */
+	for (index = 0; index < vs->dev.nvqs; ++index) {
+		if (!vhost_vq_access_ok(&vs->vqs[index].vq)) {
+			ret = -EFAULT;
+			goto err_dev;
+		}
+	}
+
+	if (!vs->vs_tpg) {
+		ret = 0;
+		goto err_dev;
+	}
+
+	for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
+		target = i;
+		tpg = vs->vs_tpg[target];
+		if (!tpg)
+			continue;
+
+		tv_tport = tpg->tport;
+		if (!tv_tport) {
+			ret = -ENODEV;
+			goto err_dev;
+		}
+
+		if (strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
+			pr_warn("tv_tport->tport_name: %s, tpg->tport_tpgt: %hu"
+				" does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
+				tv_tport->tport_name, tpg->tport_tpgt,
+				t->vhost_wwpn, t->vhost_tpgt);
+			ret = -EINVAL;
+			goto err_dev;
+		}
+		match = true;
+	}
+	if (!match)
+		goto free_vs_tpg;
+
+	/* Prevent new cmds from starting and accessing the tpgs/sessions */
+	for (i = 0; i < vs->dev.nvqs; i++) {
+		vq = &vs->vqs[i].vq;
+		mutex_lock(&vq->mutex);
+		vhost_vq_set_backend(vq, NULL);
+		mutex_unlock(&vq->mutex);
+	}
+	/* Make sure cmds are not running before tearing them down. */
+	vhost_scsi_flush(vs);
+
+	for (i = 0; i < vs->dev.nvqs; i++) {
+		vq = &vs->vqs[i].vq;
+		vhost_scsi_destroy_vq_cmds(vq);
+	}
+
+	/*
+	 * We can now release our hold on the tpg and sessions and userspace
+	 * can free them after this point.
+	 */
+	for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
+		target = i;
+		tpg = vs->vs_tpg[target];
+		if (!tpg)
+			continue;
+
+		mutex_lock(&tpg->tv_tpg_mutex);
+
+		tpg->tv_tpg_vhost_count--;
+		tpg->vhost_scsi = NULL;
+		vs->vs_tpg[target] = NULL;
+
+		mutex_unlock(&tpg->tv_tpg_mutex);
+
+		se_tpg = &tpg->se_tpg;
+		target_undepend_item(&se_tpg->tpg_group.cg_item);
+	}
+
+free_vs_tpg:
+	/*
+	 * Act as synchronize_rcu to make sure access to
+	 * old vs->vs_tpg is finished.
+	 */
+	vhost_scsi_flush(vs);
+	kfree(vs->vs_tpg);
+	vs->vs_tpg = NULL;
+	WARN_ON(vs->vs_events_nr);
+	mutex_unlock(&vs->dev.mutex);
+	return 0;
+
+err_dev:
+	mutex_unlock(&vs->dev.mutex);
+	return ret;
+}
+
+static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
+{
+	struct vhost_virtqueue *vq;
+	int i;
+
+	if (features & ~VHOST_SCSI_FEATURES)
+		return -EOPNOTSUPP;
+
+	mutex_lock(&vs->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&vs->dev)) {
+		mutex_unlock(&vs->dev.mutex);
+		return -EFAULT;
+	}
+
+	for (i = 0; i < vs->dev.nvqs; i++) {
+		vq = &vs->vqs[i].vq;
+		mutex_lock(&vq->mutex);
+		vq->acked_features = features;
+		mutex_unlock(&vq->mutex);
+	}
+	mutex_unlock(&vs->dev.mutex);
+	return 0;
+}
+
+static int vhost_scsi_open(struct inode *inode, struct file *f)
+{
+	struct vhost_scsi_virtqueue *svq;
+	struct vhost_scsi *vs;
+	struct vhost_virtqueue **vqs;
+	int r = -ENOMEM, i, nvqs = vhost_scsi_max_io_vqs;
+
+	vs = kvzalloc(sizeof(*vs), GFP_KERNEL);
+	if (!vs)
+		goto err_vs;
+
+	if (nvqs > VHOST_SCSI_MAX_IO_VQ) {
+		pr_err("Invalid max_io_vqs of %d. Using %d.\n", nvqs,
+		       VHOST_SCSI_MAX_IO_VQ);
+		nvqs = VHOST_SCSI_MAX_IO_VQ;
+	} else if (nvqs == 0) {
+		pr_err("Invalid max_io_vqs of %d. Using 1.\n", nvqs);
+		nvqs = 1;
+	}
+	nvqs += VHOST_SCSI_VQ_IO;
+
+	vs->old_inflight = kmalloc_array(nvqs, sizeof(*vs->old_inflight),
+					 GFP_KERNEL | __GFP_ZERO);
+	if (!vs->old_inflight)
+		goto err_inflight;
+
+	vs->vqs = kmalloc_array(nvqs, sizeof(*vs->vqs),
+				GFP_KERNEL | __GFP_ZERO);
+	if (!vs->vqs)
+		goto err_vqs;
+
+	vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
+	if (!vqs)
+		goto err_local_vqs;
+
+	vhost_work_init(&vs->vs_event_work, vhost_scsi_evt_work);
+
+	vs->vs_events_nr = 0;
+	vs->vs_events_missed = false;
+
+	vqs[VHOST_SCSI_VQ_CTL] = &vs->vqs[VHOST_SCSI_VQ_CTL].vq;
+	vqs[VHOST_SCSI_VQ_EVT] = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
+	vs->vqs[VHOST_SCSI_VQ_CTL].vq.handle_kick = vhost_scsi_ctl_handle_kick;
+	vs->vqs[VHOST_SCSI_VQ_EVT].vq.handle_kick = vhost_scsi_evt_handle_kick;
+	for (i = VHOST_SCSI_VQ_IO; i < nvqs; i++) {
+		svq = &vs->vqs[i];
+
+		vqs[i] = &svq->vq;
+		svq->vs = vs;
+		init_llist_head(&svq->completion_list);
+		vhost_work_init(&svq->completion_work,
+				vhost_scsi_complete_cmd_work);
+		svq->vq.handle_kick = vhost_scsi_handle_kick;
+	}
+	vhost_dev_init(&vs->dev, vqs, nvqs, UIO_MAXIOV,
+		       VHOST_SCSI_WEIGHT, 0, true, NULL);
+
+	vhost_scsi_init_inflight(vs, NULL);
+
+	f->private_data = vs;
+	return 0;
+
+err_local_vqs:
+	kfree(vs->vqs);
+err_vqs:
+	kfree(vs->old_inflight);
+err_inflight:
+	kvfree(vs);
+err_vs:
+	return r;
+}
+
+static int vhost_scsi_release(struct inode *inode, struct file *f)
+{
+	struct vhost_scsi *vs = f->private_data;
+	struct vhost_scsi_target t;
+
+	mutex_lock(&vs->dev.mutex);
+	memcpy(t.vhost_wwpn, vs->vs_vhost_wwpn, sizeof(t.vhost_wwpn));
+	mutex_unlock(&vs->dev.mutex);
+	vhost_scsi_clear_endpoint(vs, &t);
+	vhost_dev_stop(&vs->dev);
+	vhost_dev_cleanup(&vs->dev);
+	kfree(vs->dev.vqs);
+	kfree(vs->vqs);
+	kfree(vs->old_inflight);
+	kvfree(vs);
+	return 0;
+}
+
+static long
+vhost_scsi_ioctl(struct file *f,
+		 unsigned int ioctl,
+		 unsigned long arg)
+{
+	struct vhost_scsi *vs = f->private_data;
+	struct vhost_scsi_target backend;
+	void __user *argp = (void __user *)arg;
+	u64 __user *featurep = argp;
+	u32 __user *eventsp = argp;
+	u32 events_missed;
+	u64 features;
+	int r, abi_version = VHOST_SCSI_ABI_VERSION;
+	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
+
+	switch (ioctl) {
+	case VHOST_SCSI_SET_ENDPOINT:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+		if (backend.reserved != 0)
+			return -EOPNOTSUPP;
+
+		return vhost_scsi_set_endpoint(vs, &backend);
+	case VHOST_SCSI_CLEAR_ENDPOINT:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+		if (backend.reserved != 0)
+			return -EOPNOTSUPP;
+
+		return vhost_scsi_clear_endpoint(vs, &backend);
+	case VHOST_SCSI_GET_ABI_VERSION:
+		if (copy_to_user(argp, &abi_version, sizeof abi_version))
+			return -EFAULT;
+		return 0;
+	case VHOST_SCSI_SET_EVENTS_MISSED:
+		if (get_user(events_missed, eventsp))
+			return -EFAULT;
+		mutex_lock(&vq->mutex);
+		vs->vs_events_missed = events_missed;
+		mutex_unlock(&vq->mutex);
+		return 0;
+	case VHOST_SCSI_GET_EVENTS_MISSED:
+		mutex_lock(&vq->mutex);
+		events_missed = vs->vs_events_missed;
+		mutex_unlock(&vq->mutex);
+		if (put_user(events_missed, eventsp))
+			return -EFAULT;
+		return 0;
+	case VHOST_GET_FEATURES:
+		features = VHOST_SCSI_FEATURES;
+		if (copy_to_user(featurep, &features, sizeof features))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_FEATURES:
+		if (copy_from_user(&features, featurep, sizeof features))
+			return -EFAULT;
+		return vhost_scsi_set_features(vs, features);
+	case VHOST_NEW_WORKER:
+	case VHOST_FREE_WORKER:
+	case VHOST_ATTACH_VRING_WORKER:
+	case VHOST_GET_VRING_WORKER:
+		mutex_lock(&vs->dev.mutex);
+		r = vhost_worker_ioctl(&vs->dev, ioctl, argp);
+		mutex_unlock(&vs->dev.mutex);
+		return r;
+	default:
+		mutex_lock(&vs->dev.mutex);
+		r = vhost_dev_ioctl(&vs->dev, ioctl, argp);
+		/* TODO: flush backend after dev ioctl. */
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vring_ioctl(&vs->dev, ioctl, argp);
+		mutex_unlock(&vs->dev.mutex);
+		return r;
+	}
+}
+
+static const struct file_operations vhost_scsi_fops = {
+	.owner          = THIS_MODULE,
+	.release        = vhost_scsi_release,
+	.unlocked_ioctl = vhost_scsi_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.open           = vhost_scsi_open,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice vhost_scsi_misc = {
+	MISC_DYNAMIC_MINOR,
+	"vhost-scsi",
+	&vhost_scsi_fops,
+};
+
+static int __init vhost_scsi_register(void)
+{
+	return misc_register(&vhost_scsi_misc);
+}
+
+static void vhost_scsi_deregister(void)
+{
+	misc_deregister(&vhost_scsi_misc);
+}
+
+static char *vhost_scsi_dump_proto_id(struct vhost_scsi_tport *tport)
+{
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return "SAS";
+	case SCSI_PROTOCOL_FCP:
+		return "FCP";
+	case SCSI_PROTOCOL_ISCSI:
+		return "iSCSI";
+	default:
+		break;
+	}
+
+	return "Unknown";
+}
+
+static void
+vhost_scsi_do_plug(struct vhost_scsi_tpg *tpg,
+		  struct se_lun *lun, bool plug)
+{
+
+	struct vhost_scsi *vs = tpg->vhost_scsi;
+	struct vhost_virtqueue *vq;
+	u32 reason;
+
+	if (!vs)
+		return;
+
+	if (plug)
+		reason = VIRTIO_SCSI_EVT_RESET_RESCAN;
+	else
+		reason = VIRTIO_SCSI_EVT_RESET_REMOVED;
+
+	vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
+	mutex_lock(&vq->mutex);
+	/*
+	 * We can't queue events if the backend has been cleared, because
+	 * we could end up queueing an event after the flush.
+	 */
+	if (!vhost_vq_get_backend(vq))
+		goto unlock;
+
+	if (vhost_has_feature(vq, VIRTIO_SCSI_F_HOTPLUG))
+		vhost_scsi_send_evt(vs, vq, tpg, lun,
+				   VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
+unlock:
+	mutex_unlock(&vq->mutex);
+}
+
+static void vhost_scsi_hotplug(struct vhost_scsi_tpg *tpg, struct se_lun *lun)
+{
+	vhost_scsi_do_plug(tpg, lun, true);
+}
+
+static void vhost_scsi_hotunplug(struct vhost_scsi_tpg *tpg, struct se_lun *lun)
+{
+	vhost_scsi_do_plug(tpg, lun, false);
+}
+
+static int vhost_scsi_port_link(struct se_portal_group *se_tpg,
+			       struct se_lun *lun)
+{
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tpg->tv_tpg_port_count++;
+	vhost_scsi_hotplug(tpg, lun);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	return 0;
+}
+
+static void vhost_scsi_port_unlink(struct se_portal_group *se_tpg,
+				  struct se_lun *lun)
+{
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tpg->tv_tpg_port_count--;
+	vhost_scsi_hotunplug(tpg, lun);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+}
+
+static ssize_t vhost_scsi_tpg_attrib_fabric_prot_type_store(
+		struct config_item *item, const char *page, size_t count)
+{
+	struct se_portal_group *se_tpg = attrib_to_tpg(item);
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+	unsigned long val;
+	int ret = kstrtoul(page, 0, &val);
+
+	if (ret) {
+		pr_err("kstrtoul() returned %d for fabric_prot_type\n", ret);
+		return ret;
+	}
+	if (val != 0 && val != 1 && val != 3) {
+		pr_err("Invalid vhost_scsi fabric_prot_type: %lu\n", val);
+		return -EINVAL;
+	}
+	tpg->tv_fabric_prot_type = val;
+
+	return count;
+}
+
+static ssize_t vhost_scsi_tpg_attrib_fabric_prot_type_show(
+		struct config_item *item, char *page)
+{
+	struct se_portal_group *se_tpg = attrib_to_tpg(item);
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+
+	return sysfs_emit(page, "%d\n", tpg->tv_fabric_prot_type);
+}
+
+CONFIGFS_ATTR(vhost_scsi_tpg_attrib_, fabric_prot_type);
+
+static struct configfs_attribute *vhost_scsi_tpg_attrib_attrs[] = {
+	&vhost_scsi_tpg_attrib_attr_fabric_prot_type,
+	NULL,
+};
+
+static int vhost_scsi_make_nexus(struct vhost_scsi_tpg *tpg,
+				const char *name)
+{
+	struct vhost_scsi_nexus *tv_nexus;
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	if (tpg->tpg_nexus) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_debug("tpg->tpg_nexus already exists\n");
+		return -EEXIST;
+	}
+
+	tv_nexus = kzalloc(sizeof(*tv_nexus), GFP_KERNEL);
+	if (!tv_nexus) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to allocate struct vhost_scsi_nexus\n");
+		return -ENOMEM;
+	}
+	/*
+	 * Since we are running in 'demo mode' this call with generate a
+	 * struct se_node_acl for the vhost_scsi struct se_portal_group with
+	 * the SCSI Initiator port name of the passed configfs group 'name'.
+	 */
+	tv_nexus->tvn_se_sess = target_setup_session(&tpg->se_tpg, 0, 0,
+					TARGET_PROT_DIN_PASS | TARGET_PROT_DOUT_PASS,
+					(unsigned char *)name, tv_nexus, NULL);
+	if (IS_ERR(tv_nexus->tvn_se_sess)) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		kfree(tv_nexus);
+		return -ENOMEM;
+	}
+	tpg->tpg_nexus = tv_nexus;
+
+	mutex_unlock(&tpg->tv_tpg_mutex);
+	return 0;
+}
+
+static int vhost_scsi_drop_nexus(struct vhost_scsi_tpg *tpg)
+{
+	struct se_session *se_sess;
+	struct vhost_scsi_nexus *tv_nexus;
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tv_nexus = tpg->tpg_nexus;
+	if (!tv_nexus) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+
+	se_sess = tv_nexus->tvn_se_sess;
+	if (!se_sess) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+
+	if (tpg->tv_tpg_port_count != 0) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to remove TCM_vhost I_T Nexus with"
+			" active TPG port count: %d\n",
+			tpg->tv_tpg_port_count);
+		return -EBUSY;
+	}
+
+	if (tpg->tv_tpg_vhost_count != 0) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to remove TCM_vhost I_T Nexus with"
+			" active TPG vhost count: %d\n",
+			tpg->tv_tpg_vhost_count);
+		return -EBUSY;
+	}
+
+	pr_debug("TCM_vhost_ConfigFS: Removing I_T Nexus to emulated"
+		" %s Initiator Port: %s\n", vhost_scsi_dump_proto_id(tpg->tport),
+		tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
+
+	/*
+	 * Release the SCSI I_T Nexus to the emulated vhost Target Port
+	 */
+	target_remove_session(se_sess);
+	tpg->tpg_nexus = NULL;
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	kfree(tv_nexus);
+	return 0;
+}
+
+static ssize_t vhost_scsi_tpg_nexus_show(struct config_item *item, char *page)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+	struct vhost_scsi_nexus *tv_nexus;
+	ssize_t ret;
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tv_nexus = tpg->tpg_nexus;
+	if (!tv_nexus) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+	ret = sysfs_emit(page, "%s\n",
+			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	return ret;
+}
+
+static ssize_t vhost_scsi_tpg_nexus_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+	struct vhost_scsi_tport *tport_wwn = tpg->tport;
+	unsigned char i_port[VHOST_SCSI_NAMELEN], *ptr, *port_ptr;
+	int ret;
+	/*
+	 * Shutdown the active I_T nexus if 'NULL' is passed..
+	 */
+	if (!strncmp(page, "NULL", 4)) {
+		ret = vhost_scsi_drop_nexus(tpg);
+		return (!ret) ? count : ret;
+	}
+	/*
+	 * Otherwise make sure the passed virtual Initiator port WWN matches
+	 * the fabric protocol_id set in vhost_scsi_make_tport(), and call
+	 * vhost_scsi_make_nexus().
+	 */
+	if (strlen(page) >= VHOST_SCSI_NAMELEN) {
+		pr_err("Emulated NAA Sas Address: %s, exceeds"
+				" max: %d\n", page, VHOST_SCSI_NAMELEN);
+		return -EINVAL;
+	}
+	snprintf(&i_port[0], VHOST_SCSI_NAMELEN, "%s", page);
+
+	ptr = strstr(i_port, "naa.");
+	if (ptr) {
+		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
+			pr_err("Passed SAS Initiator Port %s does not"
+				" match target port protoid: %s\n", i_port,
+				vhost_scsi_dump_proto_id(tport_wwn));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[0];
+		goto check_newline;
+	}
+	ptr = strstr(i_port, "fc.");
+	if (ptr) {
+		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
+			pr_err("Passed FCP Initiator Port %s does not"
+				" match target port protoid: %s\n", i_port,
+				vhost_scsi_dump_proto_id(tport_wwn));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[3]; /* Skip over "fc." */
+		goto check_newline;
+	}
+	ptr = strstr(i_port, "iqn.");
+	if (ptr) {
+		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
+			pr_err("Passed iSCSI Initiator Port %s does not"
+				" match target port protoid: %s\n", i_port,
+				vhost_scsi_dump_proto_id(tport_wwn));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[0];
+		goto check_newline;
+	}
+	pr_err("Unable to locate prefix for emulated Initiator Port:"
+			" %s\n", i_port);
+	return -EINVAL;
+	/*
+	 * Clear any trailing newline for the NAA WWN
+	 */
+check_newline:
+	if (i_port[strlen(i_port)-1] == '\n')
+		i_port[strlen(i_port)-1] = '\0';
+
+	ret = vhost_scsi_make_nexus(tpg, port_ptr);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+CONFIGFS_ATTR(vhost_scsi_tpg_, nexus);
+
+static struct configfs_attribute *vhost_scsi_tpg_attrs[] = {
+	&vhost_scsi_tpg_attr_nexus,
+	NULL,
+};
+
+static struct se_portal_group *
+vhost_scsi_make_tpg(struct se_wwn *wwn, const char *name)
+{
+	struct vhost_scsi_tport *tport = container_of(wwn,
+			struct vhost_scsi_tport, tport_wwn);
+
+	struct vhost_scsi_tpg *tpg;
+	u16 tpgt;
+	int ret;
+
+	if (strstr(name, "tpgt_") != name)
+		return ERR_PTR(-EINVAL);
+	if (kstrtou16(name + 5, 10, &tpgt) || tpgt >= VHOST_SCSI_MAX_TARGET)
+		return ERR_PTR(-EINVAL);
+
+	tpg = kzalloc(sizeof(*tpg), GFP_KERNEL);
+	if (!tpg) {
+		pr_err("Unable to allocate struct vhost_scsi_tpg");
+		return ERR_PTR(-ENOMEM);
+	}
+	mutex_init(&tpg->tv_tpg_mutex);
+	INIT_LIST_HEAD(&tpg->tv_tpg_list);
+	tpg->tport = tport;
+	tpg->tport_tpgt = tpgt;
+
+	ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
+	if (ret < 0) {
+		kfree(tpg);
+		return NULL;
+	}
+	mutex_lock(&vhost_scsi_mutex);
+	list_add_tail(&tpg->tv_tpg_list, &vhost_scsi_list);
+	mutex_unlock(&vhost_scsi_mutex);
+
+	return &tpg->se_tpg;
+}
+
+static void vhost_scsi_drop_tpg(struct se_portal_group *se_tpg)
+{
+	struct vhost_scsi_tpg *tpg = container_of(se_tpg,
+				struct vhost_scsi_tpg, se_tpg);
+
+	mutex_lock(&vhost_scsi_mutex);
+	list_del(&tpg->tv_tpg_list);
+	mutex_unlock(&vhost_scsi_mutex);
+	/*
+	 * Release the virtual I_T Nexus for this vhost TPG
+	 */
+	vhost_scsi_drop_nexus(tpg);
+	/*
+	 * Deregister the se_tpg from TCM..
+	 */
+	core_tpg_deregister(se_tpg);
+	kfree(tpg);
+}
+
+static struct se_wwn *
+vhost_scsi_make_tport(struct target_fabric_configfs *tf,
+		     struct config_group *group,
+		     const char *name)
+{
+	struct vhost_scsi_tport *tport;
+	char *ptr;
+	u64 wwpn = 0;
+	int off = 0;
+
+	/* if (vhost_scsi_parse_wwn(name, &wwpn, 1) < 0)
+		return ERR_PTR(-EINVAL); */
+
+	tport = kzalloc(sizeof(*tport), GFP_KERNEL);
+	if (!tport) {
+		pr_err("Unable to allocate struct vhost_scsi_tport");
+		return ERR_PTR(-ENOMEM);
+	}
+	tport->tport_wwpn = wwpn;
+	/*
+	 * Determine the emulated Protocol Identifier and Target Port Name
+	 * based on the incoming configfs directory name.
+	 */
+	ptr = strstr(name, "naa.");
+	if (ptr) {
+		tport->tport_proto_id = SCSI_PROTOCOL_SAS;
+		goto check_len;
+	}
+	ptr = strstr(name, "fc.");
+	if (ptr) {
+		tport->tport_proto_id = SCSI_PROTOCOL_FCP;
+		off = 3; /* Skip over "fc." */
+		goto check_len;
+	}
+	ptr = strstr(name, "iqn.");
+	if (ptr) {
+		tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
+		goto check_len;
+	}
+
+	pr_err("Unable to locate prefix for emulated Target Port:"
+			" %s\n", name);
+	kfree(tport);
+	return ERR_PTR(-EINVAL);
+
+check_len:
+	if (strlen(name) >= VHOST_SCSI_NAMELEN) {
+		pr_err("Emulated %s Address: %s, exceeds"
+			" max: %d\n", name, vhost_scsi_dump_proto_id(tport),
+			VHOST_SCSI_NAMELEN);
+		kfree(tport);
+		return ERR_PTR(-EINVAL);
+	}
+	snprintf(&tport->tport_name[0], VHOST_SCSI_NAMELEN, "%s", &name[off]);
+
+	pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
+		" %s Address: %s\n", vhost_scsi_dump_proto_id(tport), name);
+
+	return &tport->tport_wwn;
+}
+
+static void vhost_scsi_drop_tport(struct se_wwn *wwn)
+{
+	struct vhost_scsi_tport *tport = container_of(wwn,
+				struct vhost_scsi_tport, tport_wwn);
+
+	pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
+		" %s Address: %s\n", vhost_scsi_dump_proto_id(tport),
+		tport->tport_name);
+
+	kfree(tport);
+}
+
+static ssize_t
+vhost_scsi_wwn_version_show(struct config_item *item, char *page)
+{
+	return sysfs_emit(page, "TCM_VHOST fabric module %s on %s/%s"
+		"on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname,
+		utsname()->machine);
+}
+
+CONFIGFS_ATTR_RO(vhost_scsi_wwn_, version);
+
+static struct configfs_attribute *vhost_scsi_wwn_attrs[] = {
+	&vhost_scsi_wwn_attr_version,
+	NULL,
+};
+
+static const struct target_core_fabric_ops vhost_scsi_ops = {
+	.module				= THIS_MODULE,
+	.fabric_name			= "vhost",
+	.max_data_sg_nents		= VHOST_SCSI_PREALLOC_SGLS,
+	.tpg_get_wwn			= vhost_scsi_get_fabric_wwn,
+	.tpg_get_tag			= vhost_scsi_get_tpgt,
+	.tpg_check_demo_mode		= vhost_scsi_check_true,
+	.tpg_check_demo_mode_cache	= vhost_scsi_check_true,
+	.tpg_check_prot_fabric_only	= vhost_scsi_check_prot_fabric_only,
+	.release_cmd			= vhost_scsi_release_cmd,
+	.check_stop_free		= vhost_scsi_check_stop_free,
+	.sess_get_initiator_sid		= NULL,
+	.write_pending			= vhost_scsi_write_pending,
+	.queue_data_in			= vhost_scsi_queue_data_in,
+	.queue_status			= vhost_scsi_queue_status,
+	.queue_tm_rsp			= vhost_scsi_queue_tm_rsp,
+	.aborted_task			= vhost_scsi_aborted_task,
+	/*
+	 * Setup callers for generic logic in target_core_fabric_configfs.c
+	 */
+	.fabric_make_wwn		= vhost_scsi_make_tport,
+	.fabric_drop_wwn		= vhost_scsi_drop_tport,
+	.fabric_make_tpg		= vhost_scsi_make_tpg,
+	.fabric_drop_tpg		= vhost_scsi_drop_tpg,
+	.fabric_post_link		= vhost_scsi_port_link,
+	.fabric_pre_unlink		= vhost_scsi_port_unlink,
+
+	.tfc_wwn_attrs			= vhost_scsi_wwn_attrs,
+	.tfc_tpg_base_attrs		= vhost_scsi_tpg_attrs,
+	.tfc_tpg_attrib_attrs		= vhost_scsi_tpg_attrib_attrs,
+};
+
+static int __init vhost_scsi_init(void)
+{
+	int ret = -ENOMEM;
+
+	pr_debug("TCM_VHOST fabric module %s on %s/%s"
+		" on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname,
+		utsname()->machine);
+
+	ret = vhost_scsi_register();
+	if (ret < 0)
+		goto out;
+
+	ret = target_register_template(&vhost_scsi_ops);
+	if (ret < 0)
+		goto out_vhost_scsi_deregister;
+
+	return 0;
+
+out_vhost_scsi_deregister:
+	vhost_scsi_deregister();
+out:
+	return ret;
+};
+
+static void vhost_scsi_exit(void)
+{
+	target_unregister_template(&vhost_scsi_ops);
+	vhost_scsi_deregister();
+};
+
+MODULE_DESCRIPTION("VHOST_SCSI series fabric driver");
+MODULE_ALIAS("tcm_vhost");
+MODULE_LICENSE("GPL");
+module_init(vhost_scsi_init);
+module_exit(vhost_scsi_exit);
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
new file mode 100644
index 000000000..42c955a5b
--- /dev/null
+++ b/drivers/vhost/test.c
@@ -0,0 +1,373 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2009 Red Hat, Inc.
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ * test virtio server in host kernel.
+ */
+
+#include <linux/compat.h>
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+
+#include "test.h"
+#include "vhost.h"
+
+/* Max number of bytes transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others. */
+#define VHOST_TEST_WEIGHT 0x80000
+
+/* Max number of packets transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others with
+ * pkts.
+ */
+#define VHOST_TEST_PKT_WEIGHT 256
+
+enum {
+	VHOST_TEST_VQ = 0,
+	VHOST_TEST_VQ_MAX = 1,
+};
+
+struct vhost_test {
+	struct vhost_dev dev;
+	struct vhost_virtqueue vqs[VHOST_TEST_VQ_MAX];
+};
+
+/* Expects to be always run from workqueue - which acts as
+ * read-size critical section for our kind of RCU. */
+static void handle_vq(struct vhost_test *n)
+{
+	struct vhost_virtqueue *vq = &n->vqs[VHOST_TEST_VQ];
+	unsigned out, in;
+	int head;
+	size_t len, total_len = 0;
+	void *private;
+
+	mutex_lock(&vq->mutex);
+	private = vhost_vq_get_backend(vq);
+	if (!private) {
+		mutex_unlock(&vq->mutex);
+		return;
+	}
+
+	vhost_disable_notify(&n->dev, vq);
+
+	for (;;) {
+		head = vhost_get_vq_desc(vq, vq->iov,
+					 ARRAY_SIZE(vq->iov),
+					 &out, &in,
+					 NULL, NULL);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(head < 0))
+			break;
+		/* Nothing new?  Wait for eventfd to tell us they refilled. */
+		if (head == vq->num) {
+			if (unlikely(vhost_enable_notify(&n->dev, vq))) {
+				vhost_disable_notify(&n->dev, vq);
+				continue;
+			}
+			break;
+		}
+		if (in) {
+			vq_err(vq, "Unexpected descriptor format for TX: "
+			       "out %d, int %d\n", out, in);
+			break;
+		}
+		len = iov_length(vq->iov, out);
+		/* Sanity check */
+		if (!len) {
+			vq_err(vq, "Unexpected 0 len for TX\n");
+			break;
+		}
+		vhost_add_used_and_signal(&n->dev, vq, head, 0);
+		total_len += len;
+		if (unlikely(vhost_exceeds_weight(vq, 0, total_len)))
+			break;
+	}
+
+	mutex_unlock(&vq->mutex);
+}
+
+static void handle_vq_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_test *n = container_of(vq->dev, struct vhost_test, dev);
+
+	handle_vq(n);
+}
+
+static int vhost_test_open(struct inode *inode, struct file *f)
+{
+	struct vhost_test *n = kmalloc(sizeof *n, GFP_KERNEL);
+	struct vhost_dev *dev;
+	struct vhost_virtqueue **vqs;
+
+	if (!n)
+		return -ENOMEM;
+	vqs = kmalloc_array(VHOST_TEST_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		kfree(n);
+		return -ENOMEM;
+	}
+
+	dev = &n->dev;
+	vqs[VHOST_TEST_VQ] = &n->vqs[VHOST_TEST_VQ];
+	n->vqs[VHOST_TEST_VQ].handle_kick = handle_vq_kick;
+	vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX, UIO_MAXIOV,
+		       VHOST_TEST_PKT_WEIGHT, VHOST_TEST_WEIGHT, true, NULL);
+
+	f->private_data = n;
+
+	return 0;
+}
+
+static void *vhost_test_stop_vq(struct vhost_test *n,
+				struct vhost_virtqueue *vq)
+{
+	void *private;
+
+	mutex_lock(&vq->mutex);
+	private = vhost_vq_get_backend(vq);
+	vhost_vq_set_backend(vq, NULL);
+	mutex_unlock(&vq->mutex);
+	return private;
+}
+
+static void vhost_test_stop(struct vhost_test *n, void **privatep)
+{
+	*privatep = vhost_test_stop_vq(n, n->vqs + VHOST_TEST_VQ);
+}
+
+static void vhost_test_flush(struct vhost_test *n)
+{
+	vhost_dev_flush(&n->dev);
+}
+
+static int vhost_test_release(struct inode *inode, struct file *f)
+{
+	struct vhost_test *n = f->private_data;
+	void  *private;
+
+	vhost_test_stop(n, &private);
+	vhost_test_flush(n);
+	vhost_dev_stop(&n->dev);
+	vhost_dev_cleanup(&n->dev);
+	kfree(n->dev.vqs);
+	kfree(n);
+	return 0;
+}
+
+static long vhost_test_run(struct vhost_test *n, int test)
+{
+	void *priv, *oldpriv;
+	struct vhost_virtqueue *vq;
+	int r, index;
+
+	if (test < 0 || test > 1)
+		return -EINVAL;
+
+	mutex_lock(&n->dev.mutex);
+	r = vhost_dev_check_owner(&n->dev);
+	if (r)
+		goto err;
+
+	for (index = 0; index < n->dev.nvqs; ++index) {
+		/* Verify that ring has been setup correctly. */
+		if (!vhost_vq_access_ok(&n->vqs[index])) {
+			r = -EFAULT;
+			goto err;
+		}
+	}
+
+	for (index = 0; index < n->dev.nvqs; ++index) {
+		vq = n->vqs + index;
+		mutex_lock(&vq->mutex);
+		priv = test ? n : NULL;
+
+		/* start polling new socket */
+		oldpriv = vhost_vq_get_backend(vq);
+		vhost_vq_set_backend(vq, priv);
+
+		r = vhost_vq_init_access(&n->vqs[index]);
+
+		mutex_unlock(&vq->mutex);
+
+		if (r)
+			goto err;
+
+		if (oldpriv) {
+			vhost_test_flush(n);
+		}
+	}
+
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+
+err:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
+static long vhost_test_reset_owner(struct vhost_test *n)
+{
+	void *priv = NULL;
+	long err;
+	struct vhost_iotlb *umem;
+
+	mutex_lock(&n->dev.mutex);
+	err = vhost_dev_check_owner(&n->dev);
+	if (err)
+		goto done;
+	umem = vhost_dev_reset_owner_prepare();
+	if (!umem) {
+		err = -ENOMEM;
+		goto done;
+	}
+	vhost_test_stop(n, &priv);
+	vhost_test_flush(n);
+	vhost_dev_stop(&n->dev);
+	vhost_dev_reset_owner(&n->dev, umem);
+done:
+	mutex_unlock(&n->dev.mutex);
+	return err;
+}
+
+static int vhost_test_set_features(struct vhost_test *n, u64 features)
+{
+	struct vhost_virtqueue *vq;
+
+	mutex_lock(&n->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&n->dev)) {
+		mutex_unlock(&n->dev.mutex);
+		return -EFAULT;
+	}
+	vq = &n->vqs[VHOST_TEST_VQ];
+	mutex_lock(&vq->mutex);
+	vq->acked_features = features;
+	mutex_unlock(&vq->mutex);
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+}
+
+static long vhost_test_set_backend(struct vhost_test *n, unsigned index, int fd)
+{
+	static void *backend;
+
+	const bool enable = fd != -1;
+	struct vhost_virtqueue *vq;
+	int r;
+
+	mutex_lock(&n->dev.mutex);
+	r = vhost_dev_check_owner(&n->dev);
+	if (r)
+		goto err;
+
+	if (index >= VHOST_TEST_VQ_MAX) {
+		r = -ENOBUFS;
+		goto err;
+	}
+	vq = &n->vqs[index];
+	mutex_lock(&vq->mutex);
+
+	/* Verify that ring has been setup correctly. */
+	if (!vhost_vq_access_ok(vq)) {
+		r = -EFAULT;
+		goto err_vq;
+	}
+	if (!enable) {
+		vhost_poll_stop(&vq->poll);
+		backend = vhost_vq_get_backend(vq);
+		vhost_vq_set_backend(vq, NULL);
+	} else {
+		vhost_vq_set_backend(vq, backend);
+		r = vhost_vq_init_access(vq);
+		if (r == 0)
+			r = vhost_poll_start(&vq->poll, vq->kick);
+	}
+
+	mutex_unlock(&vq->mutex);
+
+	if (enable) {
+		vhost_test_flush(n);
+	}
+
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+
+err_vq:
+	mutex_unlock(&vq->mutex);
+err:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
+static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
+			     unsigned long arg)
+{
+	struct vhost_vring_file backend;
+	struct vhost_test *n = f->private_data;
+	void __user *argp = (void __user *)arg;
+	u64 __user *featurep = argp;
+	int test;
+	u64 features;
+	int r;
+	switch (ioctl) {
+	case VHOST_TEST_RUN:
+		if (copy_from_user(&test, argp, sizeof test))
+			return -EFAULT;
+		return vhost_test_run(n, test);
+	case VHOST_TEST_SET_BACKEND:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+		return vhost_test_set_backend(n, backend.index, backend.fd);
+	case VHOST_GET_FEATURES:
+		features = VHOST_FEATURES;
+		if (copy_to_user(featurep, &features, sizeof features))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_FEATURES:
+		if (copy_from_user(&features, featurep, sizeof features))
+			return -EFAULT;
+		if (features & ~VHOST_FEATURES)
+			return -EOPNOTSUPP;
+		return vhost_test_set_features(n, features);
+	case VHOST_RESET_OWNER:
+		return vhost_test_reset_owner(n);
+	default:
+		mutex_lock(&n->dev.mutex);
+		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
+                if (r == -ENOIOCTLCMD)
+                        r = vhost_vring_ioctl(&n->dev, ioctl, argp);
+		vhost_test_flush(n);
+		mutex_unlock(&n->dev.mutex);
+		return r;
+	}
+}
+
+static const struct file_operations vhost_test_fops = {
+	.owner          = THIS_MODULE,
+	.release        = vhost_test_release,
+	.unlocked_ioctl = vhost_test_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+	.open           = vhost_test_open,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice vhost_test_misc = {
+	MISC_DYNAMIC_MINOR,
+	"vhost-test",
+	&vhost_test_fops,
+};
+module_misc_device(vhost_test_misc);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Michael S. Tsirkin");
+MODULE_DESCRIPTION("Host kernel side for virtio simulator");
diff --git a/drivers/vhost/test.h b/drivers/vhost/test.h
new file mode 100644
index 000000000..822bc4bee
--- /dev/null
+++ b/drivers/vhost/test.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LINUX_VHOST_TEST_H
+#define LINUX_VHOST_TEST_H
+
+/* Start a given test on the virtio null device. 0 stops all tests. */
+#define VHOST_TEST_RUN _IOW(VHOST_VIRTIO, 0x31, int)
+#define VHOST_TEST_SET_BACKEND _IOW(VHOST_VIRTIO, 0x32, int)
+
+#endif
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
new file mode 100644
index 000000000..fb590e346
--- /dev/null
+++ b/drivers/vhost/vdpa.c
@@ -0,0 +1,1574 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018-2020 Intel Corporation.
+ * Copyright (C) 2020 Red Hat, Inc.
+ *
+ * Author: Tiwei Bie <tiwei.bie@intel.com>
+ *         Jason Wang <jasowang@redhat.com>
+ *
+ * Thanks Michael S. Tsirkin for the valuable comments and
+ * suggestions.  And thanks to Cunming Liang and Zhihong Wang for all
+ * their supports.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/iommu.h>
+#include <linux/uuid.h>
+#include <linux/vdpa.h>
+#include <linux/nospec.h>
+#include <linux/vhost.h>
+
+#include "vhost.h"
+
+enum {
+	VHOST_VDPA_BACKEND_FEATURES =
+	(1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2) |
+	(1ULL << VHOST_BACKEND_F_IOTLB_BATCH) |
+	(1ULL << VHOST_BACKEND_F_IOTLB_ASID),
+};
+
+#define VHOST_VDPA_DEV_MAX (1U << MINORBITS)
+
+#define VHOST_VDPA_IOTLB_BUCKETS 16
+
+struct vhost_vdpa_as {
+	struct hlist_node hash_link;
+	struct vhost_iotlb iotlb;
+	u32 id;
+};
+
+struct vhost_vdpa {
+	struct vhost_dev vdev;
+	struct iommu_domain *domain;
+	struct vhost_virtqueue *vqs;
+	struct completion completion;
+	struct vdpa_device *vdpa;
+	struct hlist_head as[VHOST_VDPA_IOTLB_BUCKETS];
+	struct device dev;
+	struct cdev cdev;
+	atomic_t opened;
+	u32 nvqs;
+	int virtio_id;
+	int minor;
+	struct eventfd_ctx *config_ctx;
+	int in_batch;
+	struct vdpa_iova_range range;
+	u32 batch_asid;
+};
+
+static DEFINE_IDA(vhost_vdpa_ida);
+
+static dev_t vhost_vdpa_major;
+
+static void vhost_vdpa_iotlb_unmap(struct vhost_vdpa *v,
+				   struct vhost_iotlb *iotlb, u64 start,
+				   u64 last, u32 asid);
+
+static inline u32 iotlb_to_asid(struct vhost_iotlb *iotlb)
+{
+	struct vhost_vdpa_as *as = container_of(iotlb, struct
+						vhost_vdpa_as, iotlb);
+	return as->id;
+}
+
+static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32 asid)
+{
+	struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
+	struct vhost_vdpa_as *as;
+
+	hlist_for_each_entry(as, head, hash_link)
+		if (as->id == asid)
+			return as;
+
+	return NULL;
+}
+
+static struct vhost_iotlb *asid_to_iotlb(struct vhost_vdpa *v, u32 asid)
+{
+	struct vhost_vdpa_as *as = asid_to_as(v, asid);
+
+	if (!as)
+		return NULL;
+
+	return &as->iotlb;
+}
+
+static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
+{
+	struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
+	struct vhost_vdpa_as *as;
+
+	if (asid_to_as(v, asid))
+		return NULL;
+
+	if (asid >= v->vdpa->nas)
+		return NULL;
+
+	as = kmalloc(sizeof(*as), GFP_KERNEL);
+	if (!as)
+		return NULL;
+
+	vhost_iotlb_init(&as->iotlb, 0, 0);
+	as->id = asid;
+	hlist_add_head(&as->hash_link, head);
+
+	return as;
+}
+
+static struct vhost_vdpa_as *vhost_vdpa_find_alloc_as(struct vhost_vdpa *v,
+						      u32 asid)
+{
+	struct vhost_vdpa_as *as = asid_to_as(v, asid);
+
+	if (as)
+		return as;
+
+	return vhost_vdpa_alloc_as(v, asid);
+}
+
+static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
+{
+	struct vhost_vdpa_as *as = asid_to_as(v, asid);
+
+	if (!as)
+		return -EINVAL;
+
+	hlist_del(&as->hash_link);
+	vhost_vdpa_iotlb_unmap(v, &as->iotlb, 0ULL, 0ULL - 1, asid);
+	kfree(as);
+
+	return 0;
+}
+
+static void handle_vq_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_vdpa *v = container_of(vq->dev, struct vhost_vdpa, vdev);
+	const struct vdpa_config_ops *ops = v->vdpa->config;
+
+	ops->kick_vq(v->vdpa, vq - v->vqs);
+}
+
+static irqreturn_t vhost_vdpa_virtqueue_cb(void *private)
+{
+	struct vhost_virtqueue *vq = private;
+	struct eventfd_ctx *call_ctx = vq->call_ctx.ctx;
+
+	if (call_ctx)
+		eventfd_signal(call_ctx, 1);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t vhost_vdpa_config_cb(void *private)
+{
+	struct vhost_vdpa *v = private;
+	struct eventfd_ctx *config_ctx = v->config_ctx;
+
+	if (config_ctx)
+		eventfd_signal(config_ctx, 1);
+
+	return IRQ_HANDLED;
+}
+
+static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid)
+{
+	struct vhost_virtqueue *vq = &v->vqs[qid];
+	const struct vdpa_config_ops *ops = v->vdpa->config;
+	struct vdpa_device *vdpa = v->vdpa;
+	int ret, irq;
+
+	if (!ops->get_vq_irq)
+		return;
+
+	irq = ops->get_vq_irq(vdpa, qid);
+	if (irq < 0)
+		return;
+
+	irq_bypass_unregister_producer(&vq->call_ctx.producer);
+	if (!vq->call_ctx.ctx)
+		return;
+
+	vq->call_ctx.producer.token = vq->call_ctx.ctx;
+	vq->call_ctx.producer.irq = irq;
+	ret = irq_bypass_register_producer(&vq->call_ctx.producer);
+	if (unlikely(ret))
+		dev_info(&v->dev, "vq %u, irq bypass producer (token %p) registration fails, ret =  %d\n",
+			 qid, vq->call_ctx.producer.token, ret);
+}
+
+static void vhost_vdpa_unsetup_vq_irq(struct vhost_vdpa *v, u16 qid)
+{
+	struct vhost_virtqueue *vq = &v->vqs[qid];
+
+	irq_bypass_unregister_producer(&vq->call_ctx.producer);
+}
+
+static int vhost_vdpa_reset(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+
+	v->in_batch = 0;
+
+	return vdpa_reset(vdpa);
+}
+
+static long vhost_vdpa_bind_mm(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!vdpa->use_va || !ops->bind_mm)
+		return 0;
+
+	return ops->bind_mm(vdpa, v->vdev.mm);
+}
+
+static void vhost_vdpa_unbind_mm(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!vdpa->use_va || !ops->unbind_mm)
+		return;
+
+	ops->unbind_mm(vdpa);
+}
+
+static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 device_id;
+
+	device_id = ops->get_device_id(vdpa);
+
+	if (copy_to_user(argp, &device_id, sizeof(device_id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_get_status(struct vhost_vdpa *v, u8 __user *statusp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u8 status;
+
+	status = ops->get_status(vdpa);
+
+	if (copy_to_user(statusp, &status, sizeof(status)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u8 status, status_old;
+	u32 nvqs = v->nvqs;
+	int ret;
+	u16 i;
+
+	if (copy_from_user(&status, statusp, sizeof(status)))
+		return -EFAULT;
+
+	status_old = ops->get_status(vdpa);
+
+	/*
+	 * Userspace shouldn't remove status bits unless reset the
+	 * status to 0.
+	 */
+	if (status != 0 && (status_old & ~status) != 0)
+		return -EINVAL;
+
+	if ((status_old & VIRTIO_CONFIG_S_DRIVER_OK) && !(status & VIRTIO_CONFIG_S_DRIVER_OK))
+		for (i = 0; i < nvqs; i++)
+			vhost_vdpa_unsetup_vq_irq(v, i);
+
+	if (status == 0) {
+		ret = vdpa_reset(vdpa);
+		if (ret)
+			return ret;
+	} else
+		vdpa_set_status(vdpa, status);
+
+	if ((status & VIRTIO_CONFIG_S_DRIVER_OK) && !(status_old & VIRTIO_CONFIG_S_DRIVER_OK))
+		for (i = 0; i < nvqs; i++)
+			vhost_vdpa_setup_vq_irq(v, i);
+
+	return 0;
+}
+
+static int vhost_vdpa_config_validate(struct vhost_vdpa *v,
+				      struct vhost_vdpa_config *c)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	size_t size = vdpa->config->get_config_size(vdpa);
+
+	if (c->len == 0 || c->off > size)
+		return -EINVAL;
+
+	if (c->len > size - c->off)
+		return -E2BIG;
+
+	return 0;
+}
+
+static long vhost_vdpa_get_config(struct vhost_vdpa *v,
+				  struct vhost_vdpa_config __user *c)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	struct vhost_vdpa_config config;
+	unsigned long size = offsetof(struct vhost_vdpa_config, buf);
+	u8 *buf;
+
+	if (copy_from_user(&config, c, size))
+		return -EFAULT;
+	if (vhost_vdpa_config_validate(v, &config))
+		return -EINVAL;
+	buf = kvzalloc(config.len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	vdpa_get_config(vdpa, config.off, buf, config.len);
+
+	if (copy_to_user(c->buf, buf, config.len)) {
+		kvfree(buf);
+		return -EFAULT;
+	}
+
+	kvfree(buf);
+	return 0;
+}
+
+static long vhost_vdpa_set_config(struct vhost_vdpa *v,
+				  struct vhost_vdpa_config __user *c)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	struct vhost_vdpa_config config;
+	unsigned long size = offsetof(struct vhost_vdpa_config, buf);
+	u8 *buf;
+
+	if (copy_from_user(&config, c, size))
+		return -EFAULT;
+	if (vhost_vdpa_config_validate(v, &config))
+		return -EINVAL;
+
+	buf = vmemdup_user(c->buf, config.len);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	vdpa_set_config(vdpa, config.off, buf, config.len);
+
+	kvfree(buf);
+	return 0;
+}
+
+static bool vhost_vdpa_can_suspend(const struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	return ops->suspend;
+}
+
+static bool vhost_vdpa_can_resume(const struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	return ops->resume;
+}
+
+static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u64 features;
+
+	features = ops->get_device_features(vdpa);
+
+	if (copy_to_user(featurep, &features, sizeof(features)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static u64 vhost_vdpa_get_backend_features(const struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!ops->get_backend_features)
+		return 0;
+	else
+		return ops->get_backend_features(vdpa);
+}
+
+static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_dev *d = &v->vdev;
+	u64 actual_features;
+	u64 features;
+	int i;
+
+	/*
+	 * It's not allowed to change the features after they have
+	 * been negotiated.
+	 */
+	if (ops->get_status(vdpa) & VIRTIO_CONFIG_S_FEATURES_OK)
+		return -EBUSY;
+
+	if (copy_from_user(&features, featurep, sizeof(features)))
+		return -EFAULT;
+
+	if (vdpa_set_features(vdpa, features))
+		return -EINVAL;
+
+	/* let the vqs know what has been configured */
+	actual_features = ops->get_driver_features(vdpa);
+	for (i = 0; i < d->nvqs; ++i) {
+		struct vhost_virtqueue *vq = d->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vq->acked_features = actual_features;
+		mutex_unlock(&vq->mutex);
+	}
+
+	return 0;
+}
+
+static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u16 num;
+
+	num = ops->get_vq_num_max(vdpa);
+
+	if (copy_to_user(argp, &num, sizeof(num)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static void vhost_vdpa_config_put(struct vhost_vdpa *v)
+{
+	if (v->config_ctx) {
+		eventfd_ctx_put(v->config_ctx);
+		v->config_ctx = NULL;
+	}
+}
+
+static long vhost_vdpa_set_config_call(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_callback cb;
+	int fd;
+	struct eventfd_ctx *ctx;
+
+	cb.callback = vhost_vdpa_config_cb;
+	cb.private = v;
+	if (copy_from_user(&fd, argp, sizeof(fd)))
+		return  -EFAULT;
+
+	ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
+	swap(ctx, v->config_ctx);
+
+	if (!IS_ERR_OR_NULL(ctx))
+		eventfd_ctx_put(ctx);
+
+	if (IS_ERR(v->config_ctx)) {
+		long ret = PTR_ERR(v->config_ctx);
+
+		v->config_ctx = NULL;
+		return ret;
+	}
+
+	v->vdpa->config->set_config_cb(v->vdpa, &cb);
+
+	return 0;
+}
+
+static long vhost_vdpa_get_iova_range(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vhost_vdpa_iova_range range = {
+		.first = v->range.first,
+		.last = v->range.last,
+	};
+
+	if (copy_to_user(argp, &range, sizeof(range)))
+		return -EFAULT;
+	return 0;
+}
+
+static long vhost_vdpa_get_config_size(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 size;
+
+	size = ops->get_config_size(vdpa);
+
+	if (copy_to_user(argp, &size, sizeof(size)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+
+	if (copy_to_user(argp, &vdpa->nvqs, sizeof(vdpa->nvqs)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/* After a successful return of ioctl the device must not process more
+ * virtqueue descriptors. The device can answer to read or writes of config
+ * fields as if it were not suspended. In particular, writing to "queue_enable"
+ * with a value of 1 will not make the device start processing buffers.
+ */
+static long vhost_vdpa_suspend(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!ops->suspend)
+		return -EOPNOTSUPP;
+
+	return ops->suspend(vdpa);
+}
+
+/* After a successful return of this ioctl the device resumes processing
+ * virtqueue descriptors. The device becomes fully operational the same way it
+ * was before it was suspended.
+ */
+static long vhost_vdpa_resume(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!ops->resume)
+		return -EOPNOTSUPP;
+
+	return ops->resume(vdpa);
+}
+
+static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
+				   void __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vdpa_vq_state vq_state;
+	struct vdpa_callback cb;
+	struct vhost_virtqueue *vq;
+	struct vhost_vring_state s;
+	u32 idx;
+	long r;
+
+	r = get_user(idx, (u32 __user *)argp);
+	if (r < 0)
+		return r;
+
+	if (idx >= v->nvqs)
+		return -ENOBUFS;
+
+	idx = array_index_nospec(idx, v->nvqs);
+	vq = &v->vqs[idx];
+
+	switch (cmd) {
+	case VHOST_VDPA_SET_VRING_ENABLE:
+		if (copy_from_user(&s, argp, sizeof(s)))
+			return -EFAULT;
+		ops->set_vq_ready(vdpa, idx, s.num);
+		return 0;
+	case VHOST_VDPA_GET_VRING_GROUP:
+		if (!ops->get_vq_group)
+			return -EOPNOTSUPP;
+		s.index = idx;
+		s.num = ops->get_vq_group(vdpa, idx);
+		if (s.num >= vdpa->ngroups)
+			return -EIO;
+		else if (copy_to_user(argp, &s, sizeof(s)))
+			return -EFAULT;
+		return 0;
+	case VHOST_VDPA_SET_GROUP_ASID:
+		if (copy_from_user(&s, argp, sizeof(s)))
+			return -EFAULT;
+		if (s.num >= vdpa->nas)
+			return -EINVAL;
+		if (!ops->set_group_asid)
+			return -EOPNOTSUPP;
+		return ops->set_group_asid(vdpa, idx, s.num);
+	case VHOST_GET_VRING_BASE:
+		r = ops->get_vq_state(v->vdpa, idx, &vq_state);
+		if (r)
+			return r;
+
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+			vq->last_avail_idx = vq_state.packed.last_avail_idx |
+					     (vq_state.packed.last_avail_counter << 15);
+			vq->last_used_idx = vq_state.packed.last_used_idx |
+					    (vq_state.packed.last_used_counter << 15);
+		} else {
+			vq->last_avail_idx = vq_state.split.avail_index;
+		}
+		break;
+	}
+
+	r = vhost_vring_ioctl(&v->vdev, cmd, argp);
+	if (r)
+		return r;
+
+	switch (cmd) {
+	case VHOST_SET_VRING_ADDR:
+		if (ops->set_vq_address(vdpa, idx,
+					(u64)(uintptr_t)vq->desc,
+					(u64)(uintptr_t)vq->avail,
+					(u64)(uintptr_t)vq->used))
+			r = -EINVAL;
+		break;
+
+	case VHOST_SET_VRING_BASE:
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+			vq_state.packed.last_avail_idx = vq->last_avail_idx & 0x7fff;
+			vq_state.packed.last_avail_counter = !!(vq->last_avail_idx & 0x8000);
+			vq_state.packed.last_used_idx = vq->last_used_idx & 0x7fff;
+			vq_state.packed.last_used_counter = !!(vq->last_used_idx & 0x8000);
+		} else {
+			vq_state.split.avail_index = vq->last_avail_idx;
+		}
+		r = ops->set_vq_state(vdpa, idx, &vq_state);
+		break;
+
+	case VHOST_SET_VRING_CALL:
+		if (vq->call_ctx.ctx) {
+			cb.callback = vhost_vdpa_virtqueue_cb;
+			cb.private = vq;
+			cb.trigger = vq->call_ctx.ctx;
+		} else {
+			cb.callback = NULL;
+			cb.private = NULL;
+			cb.trigger = NULL;
+		}
+		ops->set_vq_cb(vdpa, idx, &cb);
+		vhost_vdpa_setup_vq_irq(v, idx);
+		break;
+
+	case VHOST_SET_VRING_NUM:
+		ops->set_vq_num(vdpa, idx, vq->num);
+		break;
+	}
+
+	return r;
+}
+
+static long vhost_vdpa_unlocked_ioctl(struct file *filep,
+				      unsigned int cmd, unsigned long arg)
+{
+	struct vhost_vdpa *v = filep->private_data;
+	struct vhost_dev *d = &v->vdev;
+	void __user *argp = (void __user *)arg;
+	u64 __user *featurep = argp;
+	u64 features;
+	long r = 0;
+
+	if (cmd == VHOST_SET_BACKEND_FEATURES) {
+		if (copy_from_user(&features, featurep, sizeof(features)))
+			return -EFAULT;
+		if (features & ~(VHOST_VDPA_BACKEND_FEATURES |
+				 BIT_ULL(VHOST_BACKEND_F_SUSPEND) |
+				 BIT_ULL(VHOST_BACKEND_F_RESUME) |
+				 BIT_ULL(VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK)))
+			return -EOPNOTSUPP;
+		if ((features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
+		     !vhost_vdpa_can_suspend(v))
+			return -EOPNOTSUPP;
+		if ((features & BIT_ULL(VHOST_BACKEND_F_RESUME)) &&
+		     !vhost_vdpa_can_resume(v))
+			return -EOPNOTSUPP;
+		vhost_set_backend_features(&v->vdev, features);
+		return 0;
+	}
+
+	mutex_lock(&d->mutex);
+
+	switch (cmd) {
+	case VHOST_VDPA_GET_DEVICE_ID:
+		r = vhost_vdpa_get_device_id(v, argp);
+		break;
+	case VHOST_VDPA_GET_STATUS:
+		r = vhost_vdpa_get_status(v, argp);
+		break;
+	case VHOST_VDPA_SET_STATUS:
+		r = vhost_vdpa_set_status(v, argp);
+		break;
+	case VHOST_VDPA_GET_CONFIG:
+		r = vhost_vdpa_get_config(v, argp);
+		break;
+	case VHOST_VDPA_SET_CONFIG:
+		r = vhost_vdpa_set_config(v, argp);
+		break;
+	case VHOST_GET_FEATURES:
+		r = vhost_vdpa_get_features(v, argp);
+		break;
+	case VHOST_SET_FEATURES:
+		r = vhost_vdpa_set_features(v, argp);
+		break;
+	case VHOST_VDPA_GET_VRING_NUM:
+		r = vhost_vdpa_get_vring_num(v, argp);
+		break;
+	case VHOST_VDPA_GET_GROUP_NUM:
+		if (copy_to_user(argp, &v->vdpa->ngroups,
+				 sizeof(v->vdpa->ngroups)))
+			r = -EFAULT;
+		break;
+	case VHOST_VDPA_GET_AS_NUM:
+		if (copy_to_user(argp, &v->vdpa->nas, sizeof(v->vdpa->nas)))
+			r = -EFAULT;
+		break;
+	case VHOST_SET_LOG_BASE:
+	case VHOST_SET_LOG_FD:
+		r = -ENOIOCTLCMD;
+		break;
+	case VHOST_VDPA_SET_CONFIG_CALL:
+		r = vhost_vdpa_set_config_call(v, argp);
+		break;
+	case VHOST_GET_BACKEND_FEATURES:
+		features = VHOST_VDPA_BACKEND_FEATURES;
+		if (vhost_vdpa_can_suspend(v))
+			features |= BIT_ULL(VHOST_BACKEND_F_SUSPEND);
+		if (vhost_vdpa_can_resume(v))
+			features |= BIT_ULL(VHOST_BACKEND_F_RESUME);
+		features |= vhost_vdpa_get_backend_features(v);
+		if (copy_to_user(featurep, &features, sizeof(features)))
+			r = -EFAULT;
+		break;
+	case VHOST_VDPA_GET_IOVA_RANGE:
+		r = vhost_vdpa_get_iova_range(v, argp);
+		break;
+	case VHOST_VDPA_GET_CONFIG_SIZE:
+		r = vhost_vdpa_get_config_size(v, argp);
+		break;
+	case VHOST_VDPA_GET_VQS_COUNT:
+		r = vhost_vdpa_get_vqs_count(v, argp);
+		break;
+	case VHOST_VDPA_SUSPEND:
+		r = vhost_vdpa_suspend(v);
+		break;
+	case VHOST_VDPA_RESUME:
+		r = vhost_vdpa_resume(v);
+		break;
+	default:
+		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vdpa_vring_ioctl(v, cmd, argp);
+		break;
+	}
+
+	if (r)
+		goto out;
+
+	switch (cmd) {
+	case VHOST_SET_OWNER:
+		r = vhost_vdpa_bind_mm(v);
+		if (r)
+			vhost_dev_reset_owner(d, NULL);
+		break;
+	}
+out:
+	mutex_unlock(&d->mutex);
+	return r;
+}
+static void vhost_vdpa_general_unmap(struct vhost_vdpa *v,
+				     struct vhost_iotlb_map *map, u32 asid)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	if (ops->dma_map) {
+		ops->dma_unmap(vdpa, asid, map->start, map->size);
+	} else if (ops->set_map == NULL) {
+		iommu_unmap(v->domain, map->start, map->size);
+	}
+}
+
+static void vhost_vdpa_pa_unmap(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
+				u64 start, u64 last, u32 asid)
+{
+	struct vhost_dev *dev = &v->vdev;
+	struct vhost_iotlb_map *map;
+	struct page *page;
+	unsigned long pfn, pinned;
+
+	while ((map = vhost_iotlb_itree_first(iotlb, start, last)) != NULL) {
+		pinned = PFN_DOWN(map->size);
+		for (pfn = PFN_DOWN(map->addr);
+		     pinned > 0; pfn++, pinned--) {
+			page = pfn_to_page(pfn);
+			if (map->perm & VHOST_ACCESS_WO)
+				set_page_dirty_lock(page);
+			unpin_user_page(page);
+		}
+		atomic64_sub(PFN_DOWN(map->size), &dev->mm->pinned_vm);
+		vhost_vdpa_general_unmap(v, map, asid);
+		vhost_iotlb_map_free(iotlb, map);
+	}
+}
+
+static void vhost_vdpa_va_unmap(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
+				u64 start, u64 last, u32 asid)
+{
+	struct vhost_iotlb_map *map;
+	struct vdpa_map_file *map_file;
+
+	while ((map = vhost_iotlb_itree_first(iotlb, start, last)) != NULL) {
+		map_file = (struct vdpa_map_file *)map->opaque;
+		fput(map_file->file);
+		kfree(map_file);
+		vhost_vdpa_general_unmap(v, map, asid);
+		vhost_iotlb_map_free(iotlb, map);
+	}
+}
+
+static void vhost_vdpa_iotlb_unmap(struct vhost_vdpa *v,
+				   struct vhost_iotlb *iotlb, u64 start,
+				   u64 last, u32 asid)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+
+	if (vdpa->use_va)
+		return vhost_vdpa_va_unmap(v, iotlb, start, last, asid);
+
+	return vhost_vdpa_pa_unmap(v, iotlb, start, last, asid);
+}
+
+static int perm_to_iommu_flags(u32 perm)
+{
+	int flags = 0;
+
+	switch (perm) {
+	case VHOST_ACCESS_WO:
+		flags |= IOMMU_WRITE;
+		break;
+	case VHOST_ACCESS_RO:
+		flags |= IOMMU_READ;
+		break;
+	case VHOST_ACCESS_RW:
+		flags |= (IOMMU_WRITE | IOMMU_READ);
+		break;
+	default:
+		WARN(1, "invalidate vhost IOTLB permission\n");
+		break;
+	}
+
+	return flags | IOMMU_CACHE;
+}
+
+static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
+			  u64 iova, u64 size, u64 pa, u32 perm, void *opaque)
+{
+	struct vhost_dev *dev = &v->vdev;
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 asid = iotlb_to_asid(iotlb);
+	int r = 0;
+
+	r = vhost_iotlb_add_range_ctx(iotlb, iova, iova + size - 1,
+				      pa, perm, opaque);
+	if (r)
+		return r;
+
+	if (ops->dma_map) {
+		r = ops->dma_map(vdpa, asid, iova, size, pa, perm, opaque);
+	} else if (ops->set_map) {
+		if (!v->in_batch)
+			r = ops->set_map(vdpa, asid, iotlb);
+	} else {
+		r = iommu_map(v->domain, iova, pa, size,
+			      perm_to_iommu_flags(perm), GFP_KERNEL);
+	}
+	if (r) {
+		vhost_iotlb_del_range(iotlb, iova, iova + size - 1);
+		return r;
+	}
+
+	if (!vdpa->use_va)
+		atomic64_add(PFN_DOWN(size), &dev->mm->pinned_vm);
+
+	return 0;
+}
+
+static void vhost_vdpa_unmap(struct vhost_vdpa *v,
+			     struct vhost_iotlb *iotlb,
+			     u64 iova, u64 size)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 asid = iotlb_to_asid(iotlb);
+
+	vhost_vdpa_iotlb_unmap(v, iotlb, iova, iova + size - 1, asid);
+
+	if (ops->set_map) {
+		if (!v->in_batch)
+			ops->set_map(vdpa, asid, iotlb);
+	}
+
+}
+
+static int vhost_vdpa_va_map(struct vhost_vdpa *v,
+			     struct vhost_iotlb *iotlb,
+			     u64 iova, u64 size, u64 uaddr, u32 perm)
+{
+	struct vhost_dev *dev = &v->vdev;
+	u64 offset, map_size, map_iova = iova;
+	struct vdpa_map_file *map_file;
+	struct vm_area_struct *vma;
+	int ret = 0;
+
+	mmap_read_lock(dev->mm);
+
+	while (size) {
+		vma = find_vma(dev->mm, uaddr);
+		if (!vma) {
+			ret = -EINVAL;
+			break;
+		}
+		map_size = min(size, vma->vm_end - uaddr);
+		if (!(vma->vm_file && (vma->vm_flags & VM_SHARED) &&
+			!(vma->vm_flags & (VM_IO | VM_PFNMAP))))
+			goto next;
+
+		map_file = kzalloc(sizeof(*map_file), GFP_KERNEL);
+		if (!map_file) {
+			ret = -ENOMEM;
+			break;
+		}
+		offset = (vma->vm_pgoff << PAGE_SHIFT) + uaddr - vma->vm_start;
+		map_file->offset = offset;
+		map_file->file = get_file(vma->vm_file);
+		ret = vhost_vdpa_map(v, iotlb, map_iova, map_size, uaddr,
+				     perm, map_file);
+		if (ret) {
+			fput(map_file->file);
+			kfree(map_file);
+			break;
+		}
+next:
+		size -= map_size;
+		uaddr += map_size;
+		map_iova += map_size;
+	}
+	if (ret)
+		vhost_vdpa_unmap(v, iotlb, iova, map_iova - iova);
+
+	mmap_read_unlock(dev->mm);
+
+	return ret;
+}
+
+static int vhost_vdpa_pa_map(struct vhost_vdpa *v,
+			     struct vhost_iotlb *iotlb,
+			     u64 iova, u64 size, u64 uaddr, u32 perm)
+{
+	struct vhost_dev *dev = &v->vdev;
+	struct page **page_list;
+	unsigned long list_size = PAGE_SIZE / sizeof(struct page *);
+	unsigned int gup_flags = FOLL_LONGTERM;
+	unsigned long npages, cur_base, map_pfn, last_pfn = 0;
+	unsigned long lock_limit, sz2pin, nchunks, i;
+	u64 start = iova;
+	long pinned;
+	int ret = 0;
+
+	/* Limit the use of memory for bookkeeping */
+	page_list = (struct page **) __get_free_page(GFP_KERNEL);
+	if (!page_list)
+		return -ENOMEM;
+
+	if (perm & VHOST_ACCESS_WO)
+		gup_flags |= FOLL_WRITE;
+
+	npages = PFN_UP(size + (iova & ~PAGE_MASK));
+	if (!npages) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	mmap_read_lock(dev->mm);
+
+	lock_limit = PFN_DOWN(rlimit(RLIMIT_MEMLOCK));
+	if (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	cur_base = uaddr & PAGE_MASK;
+	iova &= PAGE_MASK;
+	nchunks = 0;
+
+	while (npages) {
+		sz2pin = min_t(unsigned long, npages, list_size);
+		pinned = pin_user_pages(cur_base, sz2pin,
+					gup_flags, page_list);
+		if (sz2pin != pinned) {
+			if (pinned < 0) {
+				ret = pinned;
+			} else {
+				unpin_user_pages(page_list, pinned);
+				ret = -ENOMEM;
+			}
+			goto out;
+		}
+		nchunks++;
+
+		if (!last_pfn)
+			map_pfn = page_to_pfn(page_list[0]);
+
+		for (i = 0; i < pinned; i++) {
+			unsigned long this_pfn = page_to_pfn(page_list[i]);
+			u64 csize;
+
+			if (last_pfn && (this_pfn != last_pfn + 1)) {
+				/* Pin a contiguous chunk of memory */
+				csize = PFN_PHYS(last_pfn - map_pfn + 1);
+				ret = vhost_vdpa_map(v, iotlb, iova, csize,
+						     PFN_PHYS(map_pfn),
+						     perm, NULL);
+				if (ret) {
+					/*
+					 * Unpin the pages that are left unmapped
+					 * from this point on in the current
+					 * page_list. The remaining outstanding
+					 * ones which may stride across several
+					 * chunks will be covered in the common
+					 * error path subsequently.
+					 */
+					unpin_user_pages(&page_list[i],
+							 pinned - i);
+					goto out;
+				}
+
+				map_pfn = this_pfn;
+				iova += csize;
+				nchunks = 0;
+			}
+
+			last_pfn = this_pfn;
+		}
+
+		cur_base += PFN_PHYS(pinned);
+		npages -= pinned;
+	}
+
+	/* Pin the rest chunk */
+	ret = vhost_vdpa_map(v, iotlb, iova, PFN_PHYS(last_pfn - map_pfn + 1),
+			     PFN_PHYS(map_pfn), perm, NULL);
+out:
+	if (ret) {
+		if (nchunks) {
+			unsigned long pfn;
+
+			/*
+			 * Unpin the outstanding pages which are yet to be
+			 * mapped but haven't due to vdpa_map() or
+			 * pin_user_pages() failure.
+			 *
+			 * Mapped pages are accounted in vdpa_map(), hence
+			 * the corresponding unpinning will be handled by
+			 * vdpa_unmap().
+			 */
+			WARN_ON(!last_pfn);
+			for (pfn = map_pfn; pfn <= last_pfn; pfn++)
+				unpin_user_page(pfn_to_page(pfn));
+		}
+		vhost_vdpa_unmap(v, iotlb, start, size);
+	}
+unlock:
+	mmap_read_unlock(dev->mm);
+free:
+	free_page((unsigned long)page_list);
+	return ret;
+
+}
+
+static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
+					   struct vhost_iotlb *iotlb,
+					   struct vhost_iotlb_msg *msg)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+
+	if (msg->iova < v->range.first || !msg->size ||
+	    msg->iova > U64_MAX - msg->size + 1 ||
+	    msg->iova + msg->size - 1 > v->range.last)
+		return -EINVAL;
+
+	if (vhost_iotlb_itree_first(iotlb, msg->iova,
+				    msg->iova + msg->size - 1))
+		return -EEXIST;
+
+	if (vdpa->use_va)
+		return vhost_vdpa_va_map(v, iotlb, msg->iova, msg->size,
+					 msg->uaddr, msg->perm);
+
+	return vhost_vdpa_pa_map(v, iotlb, msg->iova, msg->size, msg->uaddr,
+				 msg->perm);
+}
+
+static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
+					struct vhost_iotlb_msg *msg)
+{
+	struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_iotlb *iotlb = NULL;
+	struct vhost_vdpa_as *as = NULL;
+	int r = 0;
+
+	mutex_lock(&dev->mutex);
+
+	r = vhost_dev_check_owner(dev);
+	if (r)
+		goto unlock;
+
+	if (msg->type == VHOST_IOTLB_UPDATE ||
+	    msg->type == VHOST_IOTLB_BATCH_BEGIN) {
+		as = vhost_vdpa_find_alloc_as(v, asid);
+		if (!as) {
+			dev_err(&v->dev, "can't find and alloc asid %d\n",
+				asid);
+			r = -EINVAL;
+			goto unlock;
+		}
+		iotlb = &as->iotlb;
+	} else
+		iotlb = asid_to_iotlb(v, asid);
+
+	if ((v->in_batch && v->batch_asid != asid) || !iotlb) {
+		if (v->in_batch && v->batch_asid != asid) {
+			dev_info(&v->dev, "batch id %d asid %d\n",
+				 v->batch_asid, asid);
+		}
+		if (!iotlb)
+			dev_err(&v->dev, "no iotlb for asid %d\n", asid);
+		r = -EINVAL;
+		goto unlock;
+	}
+
+	switch (msg->type) {
+	case VHOST_IOTLB_UPDATE:
+		r = vhost_vdpa_process_iotlb_update(v, iotlb, msg);
+		break;
+	case VHOST_IOTLB_INVALIDATE:
+		vhost_vdpa_unmap(v, iotlb, msg->iova, msg->size);
+		break;
+	case VHOST_IOTLB_BATCH_BEGIN:
+		v->batch_asid = asid;
+		v->in_batch = true;
+		break;
+	case VHOST_IOTLB_BATCH_END:
+		if (v->in_batch && ops->set_map)
+			ops->set_map(vdpa, asid, iotlb);
+		v->in_batch = false;
+		break;
+	default:
+		r = -EINVAL;
+		break;
+	}
+unlock:
+	mutex_unlock(&dev->mutex);
+
+	return r;
+}
+
+static ssize_t vhost_vdpa_chr_write_iter(struct kiocb *iocb,
+					 struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct vhost_vdpa *v = file->private_data;
+	struct vhost_dev *dev = &v->vdev;
+
+	return vhost_chr_write_iter(dev, from);
+}
+
+static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct device *dma_dev = vdpa_get_dma_dev(vdpa);
+	const struct bus_type *bus;
+	int ret;
+
+	/* Device want to do DMA by itself */
+	if (ops->set_map || ops->dma_map)
+		return 0;
+
+	bus = dma_dev->bus;
+	if (!bus)
+		return -EFAULT;
+
+	if (!device_iommu_capable(dma_dev, IOMMU_CAP_CACHE_COHERENCY)) {
+		dev_warn_once(&v->dev,
+			      "Failed to allocate domain, device is not IOMMU cache coherent capable\n");
+		return -ENOTSUPP;
+	}
+
+	v->domain = iommu_domain_alloc(bus);
+	if (!v->domain)
+		return -EIO;
+
+	ret = iommu_attach_device(v->domain, dma_dev);
+	if (ret)
+		goto err_attach;
+
+	return 0;
+
+err_attach:
+	iommu_domain_free(v->domain);
+	v->domain = NULL;
+	return ret;
+}
+
+static void vhost_vdpa_free_domain(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	struct device *dma_dev = vdpa_get_dma_dev(vdpa);
+
+	if (v->domain) {
+		iommu_detach_device(v->domain, dma_dev);
+		iommu_domain_free(v->domain);
+	}
+
+	v->domain = NULL;
+}
+
+static void vhost_vdpa_set_iova_range(struct vhost_vdpa *v)
+{
+	struct vdpa_iova_range *range = &v->range;
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (ops->get_iova_range) {
+		*range = ops->get_iova_range(vdpa);
+	} else if (v->domain && v->domain->geometry.force_aperture) {
+		range->first = v->domain->geometry.aperture_start;
+		range->last = v->domain->geometry.aperture_end;
+	} else {
+		range->first = 0;
+		range->last = ULLONG_MAX;
+	}
+}
+
+static void vhost_vdpa_cleanup(struct vhost_vdpa *v)
+{
+	struct vhost_vdpa_as *as;
+	u32 asid;
+
+	for (asid = 0; asid < v->vdpa->nas; asid++) {
+		as = asid_to_as(v, asid);
+		if (as)
+			vhost_vdpa_remove_as(v, asid);
+	}
+
+	vhost_vdpa_free_domain(v);
+	vhost_dev_cleanup(&v->vdev);
+	kfree(v->vdev.vqs);
+}
+
+static int vhost_vdpa_open(struct inode *inode, struct file *filep)
+{
+	struct vhost_vdpa *v;
+	struct vhost_dev *dev;
+	struct vhost_virtqueue **vqs;
+	int r, opened;
+	u32 i, nvqs;
+
+	v = container_of(inode->i_cdev, struct vhost_vdpa, cdev);
+
+	opened = atomic_cmpxchg(&v->opened, 0, 1);
+	if (opened)
+		return -EBUSY;
+
+	nvqs = v->nvqs;
+	r = vhost_vdpa_reset(v);
+	if (r)
+		goto err;
+
+	vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		r = -ENOMEM;
+		goto err;
+	}
+
+	dev = &v->vdev;
+	for (i = 0; i < nvqs; i++) {
+		vqs[i] = &v->vqs[i];
+		vqs[i]->handle_kick = handle_vq_kick;
+	}
+	vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false,
+		       vhost_vdpa_process_iotlb_msg);
+
+	r = vhost_vdpa_alloc_domain(v);
+	if (r)
+		goto err_alloc_domain;
+
+	vhost_vdpa_set_iova_range(v);
+
+	filep->private_data = v;
+
+	return 0;
+
+err_alloc_domain:
+	vhost_vdpa_cleanup(v);
+err:
+	atomic_dec(&v->opened);
+	return r;
+}
+
+static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
+{
+	u32 i;
+
+	for (i = 0; i < v->nvqs; i++)
+		vhost_vdpa_unsetup_vq_irq(v, i);
+}
+
+static int vhost_vdpa_release(struct inode *inode, struct file *filep)
+{
+	struct vhost_vdpa *v = filep->private_data;
+	struct vhost_dev *d = &v->vdev;
+
+	mutex_lock(&d->mutex);
+	filep->private_data = NULL;
+	vhost_vdpa_clean_irq(v);
+	vhost_vdpa_reset(v);
+	vhost_dev_stop(&v->vdev);
+	vhost_vdpa_unbind_mm(v);
+	vhost_vdpa_config_put(v);
+	vhost_vdpa_cleanup(v);
+	mutex_unlock(&d->mutex);
+
+	atomic_dec(&v->opened);
+	complete(&v->completion);
+
+	return 0;
+}
+
+#ifdef CONFIG_MMU
+static vm_fault_t vhost_vdpa_fault(struct vm_fault *vmf)
+{
+	struct vhost_vdpa *v = vmf->vma->vm_file->private_data;
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vdpa_notification_area notify;
+	struct vm_area_struct *vma = vmf->vma;
+	u16 index = vma->vm_pgoff;
+
+	notify = ops->get_vq_notification(vdpa, index);
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	if (remap_pfn_range(vma, vmf->address & PAGE_MASK,
+			    PFN_DOWN(notify.addr), PAGE_SIZE,
+			    vma->vm_page_prot))
+		return VM_FAULT_SIGBUS;
+
+	return VM_FAULT_NOPAGE;
+}
+
+static const struct vm_operations_struct vhost_vdpa_vm_ops = {
+	.fault = vhost_vdpa_fault,
+};
+
+static int vhost_vdpa_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct vhost_vdpa *v = vma->vm_file->private_data;
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vdpa_notification_area notify;
+	unsigned long index = vma->vm_pgoff;
+
+	if (vma->vm_end - vma->vm_start != PAGE_SIZE)
+		return -EINVAL;
+	if ((vma->vm_flags & VM_SHARED) == 0)
+		return -EINVAL;
+	if (vma->vm_flags & VM_READ)
+		return -EINVAL;
+	if (index > 65535)
+		return -EINVAL;
+	if (!ops->get_vq_notification)
+		return -ENOTSUPP;
+
+	/* To be safe and easily modelled by userspace, We only
+	 * support the doorbell which sits on the page boundary and
+	 * does not share the page with other registers.
+	 */
+	notify = ops->get_vq_notification(vdpa, index);
+	if (notify.addr & (PAGE_SIZE - 1))
+		return -EINVAL;
+	if (vma->vm_end - vma->vm_start != notify.size)
+		return -ENOTSUPP;
+
+	vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
+	vma->vm_ops = &vhost_vdpa_vm_ops;
+	return 0;
+}
+#endif /* CONFIG_MMU */
+
+static const struct file_operations vhost_vdpa_fops = {
+	.owner		= THIS_MODULE,
+	.open		= vhost_vdpa_open,
+	.release	= vhost_vdpa_release,
+	.write_iter	= vhost_vdpa_chr_write_iter,
+	.unlocked_ioctl	= vhost_vdpa_unlocked_ioctl,
+#ifdef CONFIG_MMU
+	.mmap		= vhost_vdpa_mmap,
+#endif /* CONFIG_MMU */
+	.compat_ioctl	= compat_ptr_ioctl,
+};
+
+static void vhost_vdpa_release_dev(struct device *device)
+{
+	struct vhost_vdpa *v =
+	       container_of(device, struct vhost_vdpa, dev);
+
+	ida_simple_remove(&vhost_vdpa_ida, v->minor);
+	kfree(v->vqs);
+	kfree(v);
+}
+
+static int vhost_vdpa_probe(struct vdpa_device *vdpa)
+{
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_vdpa *v;
+	int minor;
+	int i, r;
+
+	/* We can't support platform IOMMU device with more than 1
+	 * group or as
+	 */
+	if (!ops->set_map && !ops->dma_map &&
+	    (vdpa->ngroups > 1 || vdpa->nas > 1))
+		return -EOPNOTSUPP;
+
+	v = kzalloc(sizeof(*v), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (!v)
+		return -ENOMEM;
+
+	minor = ida_simple_get(&vhost_vdpa_ida, 0,
+			       VHOST_VDPA_DEV_MAX, GFP_KERNEL);
+	if (minor < 0) {
+		kfree(v);
+		return minor;
+	}
+
+	atomic_set(&v->opened, 0);
+	v->minor = minor;
+	v->vdpa = vdpa;
+	v->nvqs = vdpa->nvqs;
+	v->virtio_id = ops->get_device_id(vdpa);
+
+	device_initialize(&v->dev);
+	v->dev.release = vhost_vdpa_release_dev;
+	v->dev.parent = &vdpa->dev;
+	v->dev.devt = MKDEV(MAJOR(vhost_vdpa_major), minor);
+	v->vqs = kmalloc_array(v->nvqs, sizeof(struct vhost_virtqueue),
+			       GFP_KERNEL);
+	if (!v->vqs) {
+		r = -ENOMEM;
+		goto err;
+	}
+
+	r = dev_set_name(&v->dev, "vhost-vdpa-%u", minor);
+	if (r)
+		goto err;
+
+	cdev_init(&v->cdev, &vhost_vdpa_fops);
+	v->cdev.owner = THIS_MODULE;
+
+	r = cdev_device_add(&v->cdev, &v->dev);
+	if (r)
+		goto err;
+
+	init_completion(&v->completion);
+	vdpa_set_drvdata(vdpa, v);
+
+	for (i = 0; i < VHOST_VDPA_IOTLB_BUCKETS; i++)
+		INIT_HLIST_HEAD(&v->as[i]);
+
+	return 0;
+
+err:
+	put_device(&v->dev);
+	return r;
+}
+
+static void vhost_vdpa_remove(struct vdpa_device *vdpa)
+{
+	struct vhost_vdpa *v = vdpa_get_drvdata(vdpa);
+	int opened;
+
+	cdev_device_del(&v->cdev, &v->dev);
+
+	do {
+		opened = atomic_cmpxchg(&v->opened, 0, 1);
+		if (!opened)
+			break;
+		wait_for_completion(&v->completion);
+	} while (1);
+
+	put_device(&v->dev);
+}
+
+static struct vdpa_driver vhost_vdpa_driver = {
+	.driver = {
+		.name	= "vhost_vdpa",
+	},
+	.probe	= vhost_vdpa_probe,
+	.remove	= vhost_vdpa_remove,
+};
+
+static int __init vhost_vdpa_init(void)
+{
+	int r;
+
+	r = alloc_chrdev_region(&vhost_vdpa_major, 0, VHOST_VDPA_DEV_MAX,
+				"vhost-vdpa");
+	if (r)
+		goto err_alloc_chrdev;
+
+	r = vdpa_register_driver(&vhost_vdpa_driver);
+	if (r)
+		goto err_vdpa_register_driver;
+
+	return 0;
+
+err_vdpa_register_driver:
+	unregister_chrdev_region(vhost_vdpa_major, VHOST_VDPA_DEV_MAX);
+err_alloc_chrdev:
+	return r;
+}
+module_init(vhost_vdpa_init);
+
+static void __exit vhost_vdpa_exit(void)
+{
+	vdpa_unregister_driver(&vhost_vdpa_driver);
+	unregister_chrdev_region(vhost_vdpa_major, VHOST_VDPA_DEV_MAX);
+}
+module_exit(vhost_vdpa_exit);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_DESCRIPTION("vDPA-based vhost backend for virtio");
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
new file mode 100644
index 000000000..e0c181ad1
--- /dev/null
+++ b/drivers/vhost/vhost.c
@@ -0,0 +1,2937 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2006 Rusty Russell IBM Corporation
+ *
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ * Inspiration, some code, and most witty comments come from
+ * Documentation/virtual/lguest/lguest.c, by Rusty Russell
+ *
+ * Generic code for virtio server in host kernel.
+ */
+
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/uio.h>
+#include <linux/mm.h>
+#include <linux/miscdevice.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/sort.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/vhost_task.h>
+#include <linux/interval_tree_generic.h>
+#include <linux/nospec.h>
+#include <linux/kcov.h>
+
+#include "vhost.h"
+
+static ushort max_mem_regions = 64;
+module_param(max_mem_regions, ushort, 0444);
+MODULE_PARM_DESC(max_mem_regions,
+	"Maximum number of memory regions in memory map. (default: 64)");
+static int max_iotlb_entries = 2048;
+module_param(max_iotlb_entries, int, 0444);
+MODULE_PARM_DESC(max_iotlb_entries,
+	"Maximum number of iotlb entries. (default: 2048)");
+
+enum {
+	VHOST_MEMORY_F_LOG = 0x1,
+};
+
+#define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
+#define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
+
+#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
+static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
+{
+	vq->user_be = !virtio_legacy_is_little_endian();
+}
+
+static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
+{
+	vq->user_be = true;
+}
+
+static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
+{
+	vq->user_be = false;
+}
+
+static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
+{
+	struct vhost_vring_state s;
+
+	if (vq->private_data)
+		return -EBUSY;
+
+	if (copy_from_user(&s, argp, sizeof(s)))
+		return -EFAULT;
+
+	if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
+	    s.num != VHOST_VRING_BIG_ENDIAN)
+		return -EINVAL;
+
+	if (s.num == VHOST_VRING_BIG_ENDIAN)
+		vhost_enable_cross_endian_big(vq);
+	else
+		vhost_enable_cross_endian_little(vq);
+
+	return 0;
+}
+
+static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
+				   int __user *argp)
+{
+	struct vhost_vring_state s = {
+		.index = idx,
+		.num = vq->user_be
+	};
+
+	if (copy_to_user(argp, &s, sizeof(s)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static void vhost_init_is_le(struct vhost_virtqueue *vq)
+{
+	/* Note for legacy virtio: user_be is initialized at reset time
+	 * according to the host endianness. If userspace does not set an
+	 * explicit endianness, the default behavior is native endian, as
+	 * expected by legacy virtio.
+	 */
+	vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
+}
+#else
+static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
+{
+}
+
+static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
+{
+	return -ENOIOCTLCMD;
+}
+
+static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
+				   int __user *argp)
+{
+	return -ENOIOCTLCMD;
+}
+
+static void vhost_init_is_le(struct vhost_virtqueue *vq)
+{
+	vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
+		|| virtio_legacy_is_little_endian();
+}
+#endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
+
+static void vhost_reset_is_le(struct vhost_virtqueue *vq)
+{
+	vhost_init_is_le(vq);
+}
+
+struct vhost_flush_struct {
+	struct vhost_work work;
+	struct completion wait_event;
+};
+
+static void vhost_flush_work(struct vhost_work *work)
+{
+	struct vhost_flush_struct *s;
+
+	s = container_of(work, struct vhost_flush_struct, work);
+	complete(&s->wait_event);
+}
+
+static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
+			    poll_table *pt)
+{
+	struct vhost_poll *poll;
+
+	poll = container_of(pt, struct vhost_poll, table);
+	poll->wqh = wqh;
+	add_wait_queue(wqh, &poll->wait);
+}
+
+static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
+			     void *key)
+{
+	struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
+	struct vhost_work *work = &poll->work;
+
+	if (!(key_to_poll(key) & poll->mask))
+		return 0;
+
+	if (!poll->dev->use_worker)
+		work->fn(work);
+	else
+		vhost_poll_queue(poll);
+
+	return 0;
+}
+
+void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
+{
+	clear_bit(VHOST_WORK_QUEUED, &work->flags);
+	work->fn = fn;
+}
+EXPORT_SYMBOL_GPL(vhost_work_init);
+
+/* Init poll structure */
+void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
+		     __poll_t mask, struct vhost_dev *dev,
+		     struct vhost_virtqueue *vq)
+{
+	init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
+	init_poll_funcptr(&poll->table, vhost_poll_func);
+	poll->mask = mask;
+	poll->dev = dev;
+	poll->wqh = NULL;
+	poll->vq = vq;
+
+	vhost_work_init(&poll->work, fn);
+}
+EXPORT_SYMBOL_GPL(vhost_poll_init);
+
+/* Start polling a file. We add ourselves to file's wait queue. The caller must
+ * keep a reference to a file until after vhost_poll_stop is called. */
+int vhost_poll_start(struct vhost_poll *poll, struct file *file)
+{
+	__poll_t mask;
+
+	if (poll->wqh)
+		return 0;
+
+	mask = vfs_poll(file, &poll->table);
+	if (mask)
+		vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
+	if (mask & EPOLLERR) {
+		vhost_poll_stop(poll);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_poll_start);
+
+/* Stop polling a file. After this function returns, it becomes safe to drop the
+ * file reference. You must also flush afterwards. */
+void vhost_poll_stop(struct vhost_poll *poll)
+{
+	if (poll->wqh) {
+		remove_wait_queue(poll->wqh, &poll->wait);
+		poll->wqh = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(vhost_poll_stop);
+
+static void vhost_worker_queue(struct vhost_worker *worker,
+			       struct vhost_work *work)
+{
+	if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
+		/* We can only add the work to the list after we're
+		 * sure it was not in the list.
+		 * test_and_set_bit() implies a memory barrier.
+		 */
+		llist_add(&work->node, &worker->work_list);
+		vhost_task_wake(worker->vtsk);
+	}
+}
+
+bool vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work)
+{
+	struct vhost_worker *worker;
+	bool queued = false;
+
+	rcu_read_lock();
+	worker = rcu_dereference(vq->worker);
+	if (worker) {
+		queued = true;
+		vhost_worker_queue(worker, work);
+	}
+	rcu_read_unlock();
+
+	return queued;
+}
+EXPORT_SYMBOL_GPL(vhost_vq_work_queue);
+
+void vhost_vq_flush(struct vhost_virtqueue *vq)
+{
+	struct vhost_flush_struct flush;
+
+	init_completion(&flush.wait_event);
+	vhost_work_init(&flush.work, vhost_flush_work);
+
+	if (vhost_vq_work_queue(vq, &flush.work))
+		wait_for_completion(&flush.wait_event);
+}
+EXPORT_SYMBOL_GPL(vhost_vq_flush);
+
+/**
+ * vhost_worker_flush - flush a worker
+ * @worker: worker to flush
+ *
+ * This does not use RCU to protect the worker, so the device or worker
+ * mutex must be held.
+ */
+static void vhost_worker_flush(struct vhost_worker *worker)
+{
+	struct vhost_flush_struct flush;
+
+	init_completion(&flush.wait_event);
+	vhost_work_init(&flush.work, vhost_flush_work);
+
+	vhost_worker_queue(worker, &flush.work);
+	wait_for_completion(&flush.wait_event);
+}
+
+void vhost_dev_flush(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker;
+	unsigned long i;
+
+	xa_for_each(&dev->worker_xa, i, worker) {
+		mutex_lock(&worker->mutex);
+		if (!worker->attachment_cnt) {
+			mutex_unlock(&worker->mutex);
+			continue;
+		}
+		vhost_worker_flush(worker);
+		mutex_unlock(&worker->mutex);
+	}
+}
+EXPORT_SYMBOL_GPL(vhost_dev_flush);
+
+/* A lockless hint for busy polling code to exit the loop */
+bool vhost_vq_has_work(struct vhost_virtqueue *vq)
+{
+	struct vhost_worker *worker;
+	bool has_work = false;
+
+	rcu_read_lock();
+	worker = rcu_dereference(vq->worker);
+	if (worker && !llist_empty(&worker->work_list))
+		has_work = true;
+	rcu_read_unlock();
+
+	return has_work;
+}
+EXPORT_SYMBOL_GPL(vhost_vq_has_work);
+
+void vhost_poll_queue(struct vhost_poll *poll)
+{
+	vhost_vq_work_queue(poll->vq, &poll->work);
+}
+EXPORT_SYMBOL_GPL(vhost_poll_queue);
+
+static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
+{
+	int j;
+
+	for (j = 0; j < VHOST_NUM_ADDRS; j++)
+		vq->meta_iotlb[j] = NULL;
+}
+
+static void vhost_vq_meta_reset(struct vhost_dev *d)
+{
+	int i;
+
+	for (i = 0; i < d->nvqs; ++i)
+		__vhost_vq_meta_reset(d->vqs[i]);
+}
+
+static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
+{
+	call_ctx->ctx = NULL;
+	memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
+}
+
+bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
+{
+	return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
+}
+EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
+
+static void vhost_vq_reset(struct vhost_dev *dev,
+			   struct vhost_virtqueue *vq)
+{
+	vq->num = 1;
+	vq->desc = NULL;
+	vq->avail = NULL;
+	vq->used = NULL;
+	vq->last_avail_idx = 0;
+	vq->avail_idx = 0;
+	vq->last_used_idx = 0;
+	vq->signalled_used = 0;
+	vq->signalled_used_valid = false;
+	vq->used_flags = 0;
+	vq->log_used = false;
+	vq->log_addr = -1ull;
+	vq->private_data = NULL;
+	vq->acked_features = 0;
+	vq->acked_backend_features = 0;
+	vq->log_base = NULL;
+	vq->error_ctx = NULL;
+	vq->kick = NULL;
+	vq->log_ctx = NULL;
+	vhost_disable_cross_endian(vq);
+	vhost_reset_is_le(vq);
+	vq->busyloop_timeout = 0;
+	vq->umem = NULL;
+	vq->iotlb = NULL;
+	rcu_assign_pointer(vq->worker, NULL);
+	vhost_vring_call_reset(&vq->call_ctx);
+	__vhost_vq_meta_reset(vq);
+}
+
+static bool vhost_worker(void *data)
+{
+	struct vhost_worker *worker = data;
+	struct vhost_work *work, *work_next;
+	struct llist_node *node;
+
+	node = llist_del_all(&worker->work_list);
+	if (node) {
+		__set_current_state(TASK_RUNNING);
+
+		node = llist_reverse_order(node);
+		/* make sure flag is seen after deletion */
+		smp_wmb();
+		llist_for_each_entry_safe(work, work_next, node, node) {
+			clear_bit(VHOST_WORK_QUEUED, &work->flags);
+			kcov_remote_start_common(worker->kcov_handle);
+			work->fn(work);
+			kcov_remote_stop();
+			cond_resched();
+		}
+	}
+
+	return !!node;
+}
+
+static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
+{
+	kfree(vq->indirect);
+	vq->indirect = NULL;
+	kfree(vq->log);
+	vq->log = NULL;
+	kfree(vq->heads);
+	vq->heads = NULL;
+}
+
+/* Helper to allocate iovec buffers for all vqs. */
+static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
+{
+	struct vhost_virtqueue *vq;
+	int i;
+
+	for (i = 0; i < dev->nvqs; ++i) {
+		vq = dev->vqs[i];
+		vq->indirect = kmalloc_array(UIO_MAXIOV,
+					     sizeof(*vq->indirect),
+					     GFP_KERNEL);
+		vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
+					GFP_KERNEL);
+		vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
+					  GFP_KERNEL);
+		if (!vq->indirect || !vq->log || !vq->heads)
+			goto err_nomem;
+	}
+	return 0;
+
+err_nomem:
+	for (; i >= 0; --i)
+		vhost_vq_free_iovecs(dev->vqs[i]);
+	return -ENOMEM;
+}
+
+static void vhost_dev_free_iovecs(struct vhost_dev *dev)
+{
+	int i;
+
+	for (i = 0; i < dev->nvqs; ++i)
+		vhost_vq_free_iovecs(dev->vqs[i]);
+}
+
+bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
+			  int pkts, int total_len)
+{
+	struct vhost_dev *dev = vq->dev;
+
+	if ((dev->byte_weight && total_len >= dev->byte_weight) ||
+	    pkts >= dev->weight) {
+		vhost_poll_queue(&vq->poll);
+		return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
+
+static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
+				   unsigned int num)
+{
+	size_t event __maybe_unused =
+	       vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
+
+	return size_add(struct_size(vq->avail, ring, num), event);
+}
+
+static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
+				  unsigned int num)
+{
+	size_t event __maybe_unused =
+	       vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
+
+	return size_add(struct_size(vq->used, ring, num), event);
+}
+
+static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
+				  unsigned int num)
+{
+	return sizeof(*vq->desc) * num;
+}
+
+void vhost_dev_init(struct vhost_dev *dev,
+		    struct vhost_virtqueue **vqs, int nvqs,
+		    int iov_limit, int weight, int byte_weight,
+		    bool use_worker,
+		    int (*msg_handler)(struct vhost_dev *dev, u32 asid,
+				       struct vhost_iotlb_msg *msg))
+{
+	struct vhost_virtqueue *vq;
+	int i;
+
+	dev->vqs = vqs;
+	dev->nvqs = nvqs;
+	mutex_init(&dev->mutex);
+	dev->log_ctx = NULL;
+	dev->umem = NULL;
+	dev->iotlb = NULL;
+	dev->mm = NULL;
+	dev->iov_limit = iov_limit;
+	dev->weight = weight;
+	dev->byte_weight = byte_weight;
+	dev->use_worker = use_worker;
+	dev->msg_handler = msg_handler;
+	init_waitqueue_head(&dev->wait);
+	INIT_LIST_HEAD(&dev->read_list);
+	INIT_LIST_HEAD(&dev->pending_list);
+	spin_lock_init(&dev->iotlb_lock);
+	xa_init_flags(&dev->worker_xa, XA_FLAGS_ALLOC);
+
+	for (i = 0; i < dev->nvqs; ++i) {
+		vq = dev->vqs[i];
+		vq->log = NULL;
+		vq->indirect = NULL;
+		vq->heads = NULL;
+		vq->dev = dev;
+		mutex_init(&vq->mutex);
+		vhost_vq_reset(dev, vq);
+		if (vq->handle_kick)
+			vhost_poll_init(&vq->poll, vq->handle_kick,
+					EPOLLIN, dev, vq);
+	}
+}
+EXPORT_SYMBOL_GPL(vhost_dev_init);
+
+/* Caller should have device mutex */
+long vhost_dev_check_owner(struct vhost_dev *dev)
+{
+	/* Are you the owner? If not, I don't think you mean to do that */
+	return dev->mm == current->mm ? 0 : -EPERM;
+}
+EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
+
+/* Caller should have device mutex */
+bool vhost_dev_has_owner(struct vhost_dev *dev)
+{
+	return dev->mm;
+}
+EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
+
+static void vhost_attach_mm(struct vhost_dev *dev)
+{
+	/* No owner, become one */
+	if (dev->use_worker) {
+		dev->mm = get_task_mm(current);
+	} else {
+		/* vDPA device does not use worker thead, so there's
+		 * no need to hold the address space for mm. This help
+		 * to avoid deadlock in the case of mmap() which may
+		 * held the refcnt of the file and depends on release
+		 * method to remove vma.
+		 */
+		dev->mm = current->mm;
+		mmgrab(dev->mm);
+	}
+}
+
+static void vhost_detach_mm(struct vhost_dev *dev)
+{
+	if (!dev->mm)
+		return;
+
+	if (dev->use_worker)
+		mmput(dev->mm);
+	else
+		mmdrop(dev->mm);
+
+	dev->mm = NULL;
+}
+
+static void vhost_worker_destroy(struct vhost_dev *dev,
+				 struct vhost_worker *worker)
+{
+	if (!worker)
+		return;
+
+	WARN_ON(!llist_empty(&worker->work_list));
+	xa_erase(&dev->worker_xa, worker->id);
+	vhost_task_stop(worker->vtsk);
+	kfree(worker);
+}
+
+static void vhost_workers_free(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker;
+	unsigned long i;
+
+	if (!dev->use_worker)
+		return;
+
+	for (i = 0; i < dev->nvqs; i++)
+		rcu_assign_pointer(dev->vqs[i]->worker, NULL);
+	/*
+	 * Free the default worker we created and cleanup workers userspace
+	 * created but couldn't clean up (it forgot or crashed).
+	 */
+	xa_for_each(&dev->worker_xa, i, worker)
+		vhost_worker_destroy(dev, worker);
+	xa_destroy(&dev->worker_xa);
+}
+
+static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker;
+	struct vhost_task *vtsk;
+	char name[TASK_COMM_LEN];
+	int ret;
+	u32 id;
+
+	worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
+	if (!worker)
+		return NULL;
+
+	snprintf(name, sizeof(name), "vhost-%d", current->pid);
+
+	vtsk = vhost_task_create(vhost_worker, worker, name);
+	if (!vtsk)
+		goto free_worker;
+
+	mutex_init(&worker->mutex);
+	init_llist_head(&worker->work_list);
+	worker->kcov_handle = kcov_common_handle();
+	worker->vtsk = vtsk;
+
+	vhost_task_start(vtsk);
+
+	ret = xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL);
+	if (ret < 0)
+		goto stop_worker;
+	worker->id = id;
+
+	return worker;
+
+stop_worker:
+	vhost_task_stop(vtsk);
+free_worker:
+	kfree(worker);
+	return NULL;
+}
+
+/* Caller must have device mutex */
+static void __vhost_vq_attach_worker(struct vhost_virtqueue *vq,
+				     struct vhost_worker *worker)
+{
+	struct vhost_worker *old_worker;
+
+	old_worker = rcu_dereference_check(vq->worker,
+					   lockdep_is_held(&vq->dev->mutex));
+
+	mutex_lock(&worker->mutex);
+	worker->attachment_cnt++;
+	mutex_unlock(&worker->mutex);
+	rcu_assign_pointer(vq->worker, worker);
+
+	if (!old_worker)
+		return;
+	/*
+	 * Take the worker mutex to make sure we see the work queued from
+	 * device wide flushes which doesn't use RCU for execution.
+	 */
+	mutex_lock(&old_worker->mutex);
+	old_worker->attachment_cnt--;
+	/*
+	 * We don't want to call synchronize_rcu for every vq during setup
+	 * because it will slow down VM startup. If we haven't done
+	 * VHOST_SET_VRING_KICK and not done the driver specific
+	 * SET_ENDPOINT/RUNNUNG then we can skip the sync since there will
+	 * not be any works queued for scsi and net.
+	 */
+	mutex_lock(&vq->mutex);
+	if (!vhost_vq_get_backend(vq) && !vq->kick) {
+		mutex_unlock(&vq->mutex);
+		mutex_unlock(&old_worker->mutex);
+		/*
+		 * vsock can queue anytime after VHOST_VSOCK_SET_GUEST_CID.
+		 * Warn if it adds support for multiple workers but forgets to
+		 * handle the early queueing case.
+		 */
+		WARN_ON(!old_worker->attachment_cnt &&
+			!llist_empty(&old_worker->work_list));
+		return;
+	}
+	mutex_unlock(&vq->mutex);
+
+	/* Make sure new vq queue/flush/poll calls see the new worker */
+	synchronize_rcu();
+	/* Make sure whatever was queued gets run */
+	vhost_worker_flush(old_worker);
+	mutex_unlock(&old_worker->mutex);
+}
+
+ /* Caller must have device mutex */
+static int vhost_vq_attach_worker(struct vhost_virtqueue *vq,
+				  struct vhost_vring_worker *info)
+{
+	unsigned long index = info->worker_id;
+	struct vhost_dev *dev = vq->dev;
+	struct vhost_worker *worker;
+
+	if (!dev->use_worker)
+		return -EINVAL;
+
+	worker = xa_find(&dev->worker_xa, &index, UINT_MAX, XA_PRESENT);
+	if (!worker || worker->id != info->worker_id)
+		return -ENODEV;
+
+	__vhost_vq_attach_worker(vq, worker);
+	return 0;
+}
+
+/* Caller must have device mutex */
+static int vhost_new_worker(struct vhost_dev *dev,
+			    struct vhost_worker_state *info)
+{
+	struct vhost_worker *worker;
+
+	worker = vhost_worker_create(dev);
+	if (!worker)
+		return -ENOMEM;
+
+	info->worker_id = worker->id;
+	return 0;
+}
+
+/* Caller must have device mutex */
+static int vhost_free_worker(struct vhost_dev *dev,
+			     struct vhost_worker_state *info)
+{
+	unsigned long index = info->worker_id;
+	struct vhost_worker *worker;
+
+	worker = xa_find(&dev->worker_xa, &index, UINT_MAX, XA_PRESENT);
+	if (!worker || worker->id != info->worker_id)
+		return -ENODEV;
+
+	mutex_lock(&worker->mutex);
+	if (worker->attachment_cnt) {
+		mutex_unlock(&worker->mutex);
+		return -EBUSY;
+	}
+	mutex_unlock(&worker->mutex);
+
+	vhost_worker_destroy(dev, worker);
+	return 0;
+}
+
+static int vhost_get_vq_from_user(struct vhost_dev *dev, void __user *argp,
+				  struct vhost_virtqueue **vq, u32 *id)
+{
+	u32 __user *idxp = argp;
+	u32 idx;
+	long r;
+
+	r = get_user(idx, idxp);
+	if (r < 0)
+		return r;
+
+	if (idx >= dev->nvqs)
+		return -ENOBUFS;
+
+	idx = array_index_nospec(idx, dev->nvqs);
+
+	*vq = dev->vqs[idx];
+	*id = idx;
+	return 0;
+}
+
+/* Caller must have device mutex */
+long vhost_worker_ioctl(struct vhost_dev *dev, unsigned int ioctl,
+			void __user *argp)
+{
+	struct vhost_vring_worker ring_worker;
+	struct vhost_worker_state state;
+	struct vhost_worker *worker;
+	struct vhost_virtqueue *vq;
+	long ret;
+	u32 idx;
+
+	if (!dev->use_worker)
+		return -EINVAL;
+
+	if (!vhost_dev_has_owner(dev))
+		return -EINVAL;
+
+	ret = vhost_dev_check_owner(dev);
+	if (ret)
+		return ret;
+
+	switch (ioctl) {
+	/* dev worker ioctls */
+	case VHOST_NEW_WORKER:
+		ret = vhost_new_worker(dev, &state);
+		if (!ret && copy_to_user(argp, &state, sizeof(state)))
+			ret = -EFAULT;
+		return ret;
+	case VHOST_FREE_WORKER:
+		if (copy_from_user(&state, argp, sizeof(state)))
+			return -EFAULT;
+		return vhost_free_worker(dev, &state);
+	/* vring worker ioctls */
+	case VHOST_ATTACH_VRING_WORKER:
+	case VHOST_GET_VRING_WORKER:
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	ret = vhost_get_vq_from_user(dev, argp, &vq, &idx);
+	if (ret)
+		return ret;
+
+	switch (ioctl) {
+	case VHOST_ATTACH_VRING_WORKER:
+		if (copy_from_user(&ring_worker, argp, sizeof(ring_worker))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		ret = vhost_vq_attach_worker(vq, &ring_worker);
+		break;
+	case VHOST_GET_VRING_WORKER:
+		worker = rcu_dereference_check(vq->worker,
+					       lockdep_is_held(&dev->mutex));
+		if (!worker) {
+			ret = -EINVAL;
+			break;
+		}
+
+		ring_worker.index = idx;
+		ring_worker.worker_id = worker->id;
+
+		if (copy_to_user(argp, &ring_worker, sizeof(ring_worker)))
+			ret = -EFAULT;
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vhost_worker_ioctl);
+
+/* Caller should have device mutex */
+long vhost_dev_set_owner(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker;
+	int err, i;
+
+	/* Is there an owner already? */
+	if (vhost_dev_has_owner(dev)) {
+		err = -EBUSY;
+		goto err_mm;
+	}
+
+	vhost_attach_mm(dev);
+
+	err = vhost_dev_alloc_iovecs(dev);
+	if (err)
+		goto err_iovecs;
+
+	if (dev->use_worker) {
+		/*
+		 * This should be done last, because vsock can queue work
+		 * before VHOST_SET_OWNER so it simplifies the failure path
+		 * below since we don't have to worry about vsock queueing
+		 * while we free the worker.
+		 */
+		worker = vhost_worker_create(dev);
+		if (!worker) {
+			err = -ENOMEM;
+			goto err_worker;
+		}
+
+		for (i = 0; i < dev->nvqs; i++)
+			__vhost_vq_attach_worker(dev->vqs[i], worker);
+	}
+
+	return 0;
+
+err_worker:
+	vhost_dev_free_iovecs(dev);
+err_iovecs:
+	vhost_detach_mm(dev);
+err_mm:
+	return err;
+}
+EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
+
+static struct vhost_iotlb *iotlb_alloc(void)
+{
+	return vhost_iotlb_alloc(max_iotlb_entries,
+				 VHOST_IOTLB_FLAG_RETIRE);
+}
+
+struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
+{
+	return iotlb_alloc();
+}
+EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
+
+/* Caller should have device mutex */
+void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
+{
+	int i;
+
+	vhost_dev_cleanup(dev);
+
+	dev->umem = umem;
+	/* We don't need VQ locks below since vhost_dev_cleanup makes sure
+	 * VQs aren't running.
+	 */
+	for (i = 0; i < dev->nvqs; ++i)
+		dev->vqs[i]->umem = umem;
+}
+EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
+
+void vhost_dev_stop(struct vhost_dev *dev)
+{
+	int i;
+
+	for (i = 0; i < dev->nvqs; ++i) {
+		if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick)
+			vhost_poll_stop(&dev->vqs[i]->poll);
+	}
+
+	vhost_dev_flush(dev);
+}
+EXPORT_SYMBOL_GPL(vhost_dev_stop);
+
+void vhost_clear_msg(struct vhost_dev *dev)
+{
+	struct vhost_msg_node *node, *n;
+
+	spin_lock(&dev->iotlb_lock);
+
+	list_for_each_entry_safe(node, n, &dev->read_list, node) {
+		list_del(&node->node);
+		kfree(node);
+	}
+
+	list_for_each_entry_safe(node, n, &dev->pending_list, node) {
+		list_del(&node->node);
+		kfree(node);
+	}
+
+	spin_unlock(&dev->iotlb_lock);
+}
+EXPORT_SYMBOL_GPL(vhost_clear_msg);
+
+void vhost_dev_cleanup(struct vhost_dev *dev)
+{
+	int i;
+
+	for (i = 0; i < dev->nvqs; ++i) {
+		if (dev->vqs[i]->error_ctx)
+			eventfd_ctx_put(dev->vqs[i]->error_ctx);
+		if (dev->vqs[i]->kick)
+			fput(dev->vqs[i]->kick);
+		if (dev->vqs[i]->call_ctx.ctx)
+			eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
+		vhost_vq_reset(dev, dev->vqs[i]);
+	}
+	vhost_dev_free_iovecs(dev);
+	if (dev->log_ctx)
+		eventfd_ctx_put(dev->log_ctx);
+	dev->log_ctx = NULL;
+	/* No one will access memory at this point */
+	vhost_iotlb_free(dev->umem);
+	dev->umem = NULL;
+	vhost_iotlb_free(dev->iotlb);
+	dev->iotlb = NULL;
+	vhost_clear_msg(dev);
+	wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
+	vhost_workers_free(dev);
+	vhost_detach_mm(dev);
+}
+EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
+
+static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
+{
+	u64 a = addr / VHOST_PAGE_SIZE / 8;
+
+	/* Make sure 64 bit math will not overflow. */
+	if (a > ULONG_MAX - (unsigned long)log_base ||
+	    a + (unsigned long)log_base > ULONG_MAX)
+		return false;
+
+	return access_ok(log_base + a,
+			 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
+}
+
+/* Make sure 64 bit math will not overflow. */
+static bool vhost_overflow(u64 uaddr, u64 size)
+{
+	if (uaddr > ULONG_MAX || size > ULONG_MAX)
+		return true;
+
+	if (!size)
+		return false;
+
+	return uaddr > ULONG_MAX - size + 1;
+}
+
+/* Caller should have vq mutex and device mutex. */
+static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
+				int log_all)
+{
+	struct vhost_iotlb_map *map;
+
+	if (!umem)
+		return false;
+
+	list_for_each_entry(map, &umem->list, link) {
+		unsigned long a = map->addr;
+
+		if (vhost_overflow(map->addr, map->size))
+			return false;
+
+
+		if (!access_ok((void __user *)a, map->size))
+			return false;
+		else if (log_all && !log_access_ok(log_base,
+						   map->start,
+						   map->size))
+			return false;
+	}
+	return true;
+}
+
+static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
+					       u64 addr, unsigned int size,
+					       int type)
+{
+	const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
+
+	if (!map)
+		return NULL;
+
+	return (void __user *)(uintptr_t)(map->addr + addr - map->start);
+}
+
+/* Can we switch to this memory table? */
+/* Caller should have device mutex but not vq mutex */
+static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
+			     int log_all)
+{
+	int i;
+
+	for (i = 0; i < d->nvqs; ++i) {
+		bool ok;
+		bool log;
+
+		mutex_lock(&d->vqs[i]->mutex);
+		log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
+		/* If ring is inactive, will check when it's enabled. */
+		if (d->vqs[i]->private_data)
+			ok = vq_memory_access_ok(d->vqs[i]->log_base,
+						 umem, log);
+		else
+			ok = true;
+		mutex_unlock(&d->vqs[i]->mutex);
+		if (!ok)
+			return false;
+	}
+	return true;
+}
+
+static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
+			  struct iovec iov[], int iov_size, int access);
+
+static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
+			      const void *from, unsigned size)
+{
+	int ret;
+
+	if (!vq->iotlb)
+		return __copy_to_user(to, from, size);
+	else {
+		/* This function should be called after iotlb
+		 * prefetch, which means we're sure that all vq
+		 * could be access through iotlb. So -EAGAIN should
+		 * not happen in this case.
+		 */
+		struct iov_iter t;
+		void __user *uaddr = vhost_vq_meta_fetch(vq,
+				     (u64)(uintptr_t)to, size,
+				     VHOST_ADDR_USED);
+
+		if (uaddr)
+			return __copy_to_user(uaddr, from, size);
+
+		ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
+				     ARRAY_SIZE(vq->iotlb_iov),
+				     VHOST_ACCESS_WO);
+		if (ret < 0)
+			goto out;
+		iov_iter_init(&t, ITER_DEST, vq->iotlb_iov, ret, size);
+		ret = copy_to_iter(from, size, &t);
+		if (ret == size)
+			ret = 0;
+	}
+out:
+	return ret;
+}
+
+static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
+				void __user *from, unsigned size)
+{
+	int ret;
+
+	if (!vq->iotlb)
+		return __copy_from_user(to, from, size);
+	else {
+		/* This function should be called after iotlb
+		 * prefetch, which means we're sure that vq
+		 * could be access through iotlb. So -EAGAIN should
+		 * not happen in this case.
+		 */
+		void __user *uaddr = vhost_vq_meta_fetch(vq,
+				     (u64)(uintptr_t)from, size,
+				     VHOST_ADDR_DESC);
+		struct iov_iter f;
+
+		if (uaddr)
+			return __copy_from_user(to, uaddr, size);
+
+		ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
+				     ARRAY_SIZE(vq->iotlb_iov),
+				     VHOST_ACCESS_RO);
+		if (ret < 0) {
+			vq_err(vq, "IOTLB translation failure: uaddr "
+			       "%p size 0x%llx\n", from,
+			       (unsigned long long) size);
+			goto out;
+		}
+		iov_iter_init(&f, ITER_SOURCE, vq->iotlb_iov, ret, size);
+		ret = copy_from_iter(to, size, &f);
+		if (ret == size)
+			ret = 0;
+	}
+
+out:
+	return ret;
+}
+
+static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
+					  void __user *addr, unsigned int size,
+					  int type)
+{
+	int ret;
+
+	ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
+			     ARRAY_SIZE(vq->iotlb_iov),
+			     VHOST_ACCESS_RO);
+	if (ret < 0) {
+		vq_err(vq, "IOTLB translation failure: uaddr "
+			"%p size 0x%llx\n", addr,
+			(unsigned long long) size);
+		return NULL;
+	}
+
+	if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
+		vq_err(vq, "Non atomic userspace memory access: uaddr "
+			"%p size 0x%llx\n", addr,
+			(unsigned long long) size);
+		return NULL;
+	}
+
+	return vq->iotlb_iov[0].iov_base;
+}
+
+/* This function should be called after iotlb
+ * prefetch, which means we're sure that vq
+ * could be access through iotlb. So -EAGAIN should
+ * not happen in this case.
+ */
+static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
+					    void __user *addr, unsigned int size,
+					    int type)
+{
+	void __user *uaddr = vhost_vq_meta_fetch(vq,
+			     (u64)(uintptr_t)addr, size, type);
+	if (uaddr)
+		return uaddr;
+
+	return __vhost_get_user_slow(vq, addr, size, type);
+}
+
+#define vhost_put_user(vq, x, ptr)		\
+({ \
+	int ret; \
+	if (!vq->iotlb) { \
+		ret = __put_user(x, ptr); \
+	} else { \
+		__typeof__(ptr) to = \
+			(__typeof__(ptr)) __vhost_get_user(vq, ptr,	\
+					  sizeof(*ptr), VHOST_ADDR_USED); \
+		if (to != NULL) \
+			ret = __put_user(x, to); \
+		else \
+			ret = -EFAULT;	\
+	} \
+	ret; \
+})
+
+static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
+{
+	return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
+			      vhost_avail_event(vq));
+}
+
+static inline int vhost_put_used(struct vhost_virtqueue *vq,
+				 struct vring_used_elem *head, int idx,
+				 int count)
+{
+	return vhost_copy_to_user(vq, vq->used->ring + idx, head,
+				  count * sizeof(*head));
+}
+
+static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
+
+{
+	return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
+			      &vq->used->flags);
+}
+
+static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
+
+{
+	return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
+			      &vq->used->idx);
+}
+
+#define vhost_get_user(vq, x, ptr, type)		\
+({ \
+	int ret; \
+	if (!vq->iotlb) { \
+		ret = __get_user(x, ptr); \
+	} else { \
+		__typeof__(ptr) from = \
+			(__typeof__(ptr)) __vhost_get_user(vq, ptr, \
+							   sizeof(*ptr), \
+							   type); \
+		if (from != NULL) \
+			ret = __get_user(x, from); \
+		else \
+			ret = -EFAULT; \
+	} \
+	ret; \
+})
+
+#define vhost_get_avail(vq, x, ptr) \
+	vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
+
+#define vhost_get_used(vq, x, ptr) \
+	vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
+
+static void vhost_dev_lock_vqs(struct vhost_dev *d)
+{
+	int i = 0;
+	for (i = 0; i < d->nvqs; ++i)
+		mutex_lock_nested(&d->vqs[i]->mutex, i);
+}
+
+static void vhost_dev_unlock_vqs(struct vhost_dev *d)
+{
+	int i = 0;
+	for (i = 0; i < d->nvqs; ++i)
+		mutex_unlock(&d->vqs[i]->mutex);
+}
+
+static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
+				      __virtio16 *idx)
+{
+	return vhost_get_avail(vq, *idx, &vq->avail->idx);
+}
+
+static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
+				       __virtio16 *head, int idx)
+{
+	return vhost_get_avail(vq, *head,
+			       &vq->avail->ring[idx & (vq->num - 1)]);
+}
+
+static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
+					__virtio16 *flags)
+{
+	return vhost_get_avail(vq, *flags, &vq->avail->flags);
+}
+
+static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
+				       __virtio16 *event)
+{
+	return vhost_get_avail(vq, *event, vhost_used_event(vq));
+}
+
+static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
+				     __virtio16 *idx)
+{
+	return vhost_get_used(vq, *idx, &vq->used->idx);
+}
+
+static inline int vhost_get_desc(struct vhost_virtqueue *vq,
+				 struct vring_desc *desc, int idx)
+{
+	return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
+}
+
+static void vhost_iotlb_notify_vq(struct vhost_dev *d,
+				  struct vhost_iotlb_msg *msg)
+{
+	struct vhost_msg_node *node, *n;
+
+	spin_lock(&d->iotlb_lock);
+
+	list_for_each_entry_safe(node, n, &d->pending_list, node) {
+		struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
+		if (msg->iova <= vq_msg->iova &&
+		    msg->iova + msg->size - 1 >= vq_msg->iova &&
+		    vq_msg->type == VHOST_IOTLB_MISS) {
+			vhost_poll_queue(&node->vq->poll);
+			list_del(&node->node);
+			kfree(node);
+		}
+	}
+
+	spin_unlock(&d->iotlb_lock);
+}
+
+static bool umem_access_ok(u64 uaddr, u64 size, int access)
+{
+	unsigned long a = uaddr;
+
+	/* Make sure 64 bit math will not overflow. */
+	if (vhost_overflow(uaddr, size))
+		return false;
+
+	if ((access & VHOST_ACCESS_RO) &&
+	    !access_ok((void __user *)a, size))
+		return false;
+	if ((access & VHOST_ACCESS_WO) &&
+	    !access_ok((void __user *)a, size))
+		return false;
+	return true;
+}
+
+static int vhost_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
+				   struct vhost_iotlb_msg *msg)
+{
+	int ret = 0;
+
+	if (asid != 0)
+		return -EINVAL;
+
+	mutex_lock(&dev->mutex);
+	vhost_dev_lock_vqs(dev);
+	switch (msg->type) {
+	case VHOST_IOTLB_UPDATE:
+		if (!dev->iotlb) {
+			ret = -EFAULT;
+			break;
+		}
+		if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
+			ret = -EFAULT;
+			break;
+		}
+		vhost_vq_meta_reset(dev);
+		if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
+					  msg->iova + msg->size - 1,
+					  msg->uaddr, msg->perm)) {
+			ret = -ENOMEM;
+			break;
+		}
+		vhost_iotlb_notify_vq(dev, msg);
+		break;
+	case VHOST_IOTLB_INVALIDATE:
+		if (!dev->iotlb) {
+			ret = -EFAULT;
+			break;
+		}
+		vhost_vq_meta_reset(dev);
+		vhost_iotlb_del_range(dev->iotlb, msg->iova,
+				      msg->iova + msg->size - 1);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	vhost_dev_unlock_vqs(dev);
+	mutex_unlock(&dev->mutex);
+
+	return ret;
+}
+ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
+			     struct iov_iter *from)
+{
+	struct vhost_iotlb_msg msg;
+	size_t offset;
+	int type, ret;
+	u32 asid = 0;
+
+	ret = copy_from_iter(&type, sizeof(type), from);
+	if (ret != sizeof(type)) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	switch (type) {
+	case VHOST_IOTLB_MSG:
+		/* There maybe a hole after type for V1 message type,
+		 * so skip it here.
+		 */
+		offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
+		break;
+	case VHOST_IOTLB_MSG_V2:
+		if (vhost_backend_has_feature(dev->vqs[0],
+					      VHOST_BACKEND_F_IOTLB_ASID)) {
+			ret = copy_from_iter(&asid, sizeof(asid), from);
+			if (ret != sizeof(asid)) {
+				ret = -EINVAL;
+				goto done;
+			}
+			offset = 0;
+		} else
+			offset = sizeof(__u32);
+		break;
+	default:
+		ret = -EINVAL;
+		goto done;
+	}
+
+	iov_iter_advance(from, offset);
+	ret = copy_from_iter(&msg, sizeof(msg), from);
+	if (ret != sizeof(msg)) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	if (msg.type == VHOST_IOTLB_UPDATE && msg.size == 0) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	if (dev->msg_handler)
+		ret = dev->msg_handler(dev, asid, &msg);
+	else
+		ret = vhost_process_iotlb_msg(dev, asid, &msg);
+	if (ret) {
+		ret = -EFAULT;
+		goto done;
+	}
+
+	ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
+	      sizeof(struct vhost_msg_v2);
+done:
+	return ret;
+}
+EXPORT_SYMBOL(vhost_chr_write_iter);
+
+__poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
+			    poll_table *wait)
+{
+	__poll_t mask = 0;
+
+	poll_wait(file, &dev->wait, wait);
+
+	if (!list_empty(&dev->read_list))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	return mask;
+}
+EXPORT_SYMBOL(vhost_chr_poll);
+
+ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
+			    int noblock)
+{
+	DEFINE_WAIT(wait);
+	struct vhost_msg_node *node;
+	ssize_t ret = 0;
+	unsigned size = sizeof(struct vhost_msg);
+
+	if (iov_iter_count(to) < size)
+		return 0;
+
+	while (1) {
+		if (!noblock)
+			prepare_to_wait(&dev->wait, &wait,
+					TASK_INTERRUPTIBLE);
+
+		node = vhost_dequeue_msg(dev, &dev->read_list);
+		if (node)
+			break;
+		if (noblock) {
+			ret = -EAGAIN;
+			break;
+		}
+		if (signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+		if (!dev->iotlb) {
+			ret = -EBADFD;
+			break;
+		}
+
+		schedule();
+	}
+
+	if (!noblock)
+		finish_wait(&dev->wait, &wait);
+
+	if (node) {
+		struct vhost_iotlb_msg *msg;
+		void *start = &node->msg;
+
+		switch (node->msg.type) {
+		case VHOST_IOTLB_MSG:
+			size = sizeof(node->msg);
+			msg = &node->msg.iotlb;
+			break;
+		case VHOST_IOTLB_MSG_V2:
+			size = sizeof(node->msg_v2);
+			msg = &node->msg_v2.iotlb;
+			break;
+		default:
+			BUG();
+			break;
+		}
+
+		ret = copy_to_iter(start, size, to);
+		if (ret != size || msg->type != VHOST_IOTLB_MISS) {
+			kfree(node);
+			return ret;
+		}
+		vhost_enqueue_msg(dev, &dev->pending_list, node);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
+
+static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
+{
+	struct vhost_dev *dev = vq->dev;
+	struct vhost_msg_node *node;
+	struct vhost_iotlb_msg *msg;
+	bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
+
+	node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
+	if (!node)
+		return -ENOMEM;
+
+	if (v2) {
+		node->msg_v2.type = VHOST_IOTLB_MSG_V2;
+		msg = &node->msg_v2.iotlb;
+	} else {
+		msg = &node->msg.iotlb;
+	}
+
+	msg->type = VHOST_IOTLB_MISS;
+	msg->iova = iova;
+	msg->perm = access;
+
+	vhost_enqueue_msg(dev, &dev->read_list, node);
+
+	return 0;
+}
+
+static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
+			 vring_desc_t __user *desc,
+			 vring_avail_t __user *avail,
+			 vring_used_t __user *used)
+
+{
+	/* If an IOTLB device is present, the vring addresses are
+	 * GIOVAs. Access validation occurs at prefetch time. */
+	if (vq->iotlb)
+		return true;
+
+	return access_ok(desc, vhost_get_desc_size(vq, num)) &&
+	       access_ok(avail, vhost_get_avail_size(vq, num)) &&
+	       access_ok(used, vhost_get_used_size(vq, num));
+}
+
+static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
+				 const struct vhost_iotlb_map *map,
+				 int type)
+{
+	int access = (type == VHOST_ADDR_USED) ?
+		     VHOST_ACCESS_WO : VHOST_ACCESS_RO;
+
+	if (likely(map->perm & access))
+		vq->meta_iotlb[type] = map;
+}
+
+static bool iotlb_access_ok(struct vhost_virtqueue *vq,
+			    int access, u64 addr, u64 len, int type)
+{
+	const struct vhost_iotlb_map *map;
+	struct vhost_iotlb *umem = vq->iotlb;
+	u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
+
+	if (vhost_vq_meta_fetch(vq, addr, len, type))
+		return true;
+
+	while (len > s) {
+		map = vhost_iotlb_itree_first(umem, addr, last);
+		if (map == NULL || map->start > addr) {
+			vhost_iotlb_miss(vq, addr, access);
+			return false;
+		} else if (!(map->perm & access)) {
+			/* Report the possible access violation by
+			 * request another translation from userspace.
+			 */
+			return false;
+		}
+
+		size = map->size - addr + map->start;
+
+		if (orig_addr == addr && size >= len)
+			vhost_vq_meta_update(vq, map, type);
+
+		s += size;
+		addr += size;
+	}
+
+	return true;
+}
+
+int vq_meta_prefetch(struct vhost_virtqueue *vq)
+{
+	unsigned int num = vq->num;
+
+	if (!vq->iotlb)
+		return 1;
+
+	return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
+			       vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
+	       iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
+			       vhost_get_avail_size(vq, num),
+			       VHOST_ADDR_AVAIL) &&
+	       iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
+			       vhost_get_used_size(vq, num), VHOST_ADDR_USED);
+}
+EXPORT_SYMBOL_GPL(vq_meta_prefetch);
+
+/* Can we log writes? */
+/* Caller should have device mutex but not vq mutex */
+bool vhost_log_access_ok(struct vhost_dev *dev)
+{
+	return memory_access_ok(dev, dev->umem, 1);
+}
+EXPORT_SYMBOL_GPL(vhost_log_access_ok);
+
+static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
+				  void __user *log_base,
+				  bool log_used,
+				  u64 log_addr)
+{
+	/* If an IOTLB device is present, log_addr is a GIOVA that
+	 * will never be logged by log_used(). */
+	if (vq->iotlb)
+		return true;
+
+	return !log_used || log_access_ok(log_base, log_addr,
+					  vhost_get_used_size(vq, vq->num));
+}
+
+/* Verify access for write logging. */
+/* Caller should have vq mutex and device mutex */
+static bool vq_log_access_ok(struct vhost_virtqueue *vq,
+			     void __user *log_base)
+{
+	return vq_memory_access_ok(log_base, vq->umem,
+				   vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
+		vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
+}
+
+/* Can we start vq? */
+/* Caller should have vq mutex and device mutex */
+bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
+{
+	if (!vq_log_access_ok(vq, vq->log_base))
+		return false;
+
+	return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
+}
+EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
+
+static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
+{
+	struct vhost_memory mem, *newmem;
+	struct vhost_memory_region *region;
+	struct vhost_iotlb *newumem, *oldumem;
+	unsigned long size = offsetof(struct vhost_memory, regions);
+	int i;
+
+	if (copy_from_user(&mem, m, size))
+		return -EFAULT;
+	if (mem.padding)
+		return -EOPNOTSUPP;
+	if (mem.nregions > max_mem_regions)
+		return -E2BIG;
+	newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
+			GFP_KERNEL);
+	if (!newmem)
+		return -ENOMEM;
+
+	memcpy(newmem, &mem, size);
+	if (copy_from_user(newmem->regions, m->regions,
+			   flex_array_size(newmem, regions, mem.nregions))) {
+		kvfree(newmem);
+		return -EFAULT;
+	}
+
+	newumem = iotlb_alloc();
+	if (!newumem) {
+		kvfree(newmem);
+		return -ENOMEM;
+	}
+
+	for (region = newmem->regions;
+	     region < newmem->regions + mem.nregions;
+	     region++) {
+		if (vhost_iotlb_add_range(newumem,
+					  region->guest_phys_addr,
+					  region->guest_phys_addr +
+					  region->memory_size - 1,
+					  region->userspace_addr,
+					  VHOST_MAP_RW))
+			goto err;
+	}
+
+	if (!memory_access_ok(d, newumem, 0))
+		goto err;
+
+	oldumem = d->umem;
+	d->umem = newumem;
+
+	/* All memory accesses are done under some VQ mutex. */
+	for (i = 0; i < d->nvqs; ++i) {
+		mutex_lock(&d->vqs[i]->mutex);
+		d->vqs[i]->umem = newumem;
+		mutex_unlock(&d->vqs[i]->mutex);
+	}
+
+	kvfree(newmem);
+	vhost_iotlb_free(oldumem);
+	return 0;
+
+err:
+	vhost_iotlb_free(newumem);
+	kvfree(newmem);
+	return -EFAULT;
+}
+
+static long vhost_vring_set_num(struct vhost_dev *d,
+				struct vhost_virtqueue *vq,
+				void __user *argp)
+{
+	struct vhost_vring_state s;
+
+	/* Resizing ring with an active backend?
+	 * You don't want to do that. */
+	if (vq->private_data)
+		return -EBUSY;
+
+	if (copy_from_user(&s, argp, sizeof s))
+		return -EFAULT;
+
+	if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
+		return -EINVAL;
+	vq->num = s.num;
+
+	return 0;
+}
+
+static long vhost_vring_set_addr(struct vhost_dev *d,
+				 struct vhost_virtqueue *vq,
+				 void __user *argp)
+{
+	struct vhost_vring_addr a;
+
+	if (copy_from_user(&a, argp, sizeof a))
+		return -EFAULT;
+	if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
+		return -EOPNOTSUPP;
+
+	/* For 32bit, verify that the top 32bits of the user
+	   data are set to zero. */
+	if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
+	    (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
+	    (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
+		return -EFAULT;
+
+	/* Make sure it's safe to cast pointers to vring types. */
+	BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
+	BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
+	if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
+	    (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
+	    (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
+		return -EINVAL;
+
+	/* We only verify access here if backend is configured.
+	 * If it is not, we don't as size might not have been setup.
+	 * We will verify when backend is configured. */
+	if (vq->private_data) {
+		if (!vq_access_ok(vq, vq->num,
+			(void __user *)(unsigned long)a.desc_user_addr,
+			(void __user *)(unsigned long)a.avail_user_addr,
+			(void __user *)(unsigned long)a.used_user_addr))
+			return -EINVAL;
+
+		/* Also validate log access for used ring if enabled. */
+		if (!vq_log_used_access_ok(vq, vq->log_base,
+				a.flags & (0x1 << VHOST_VRING_F_LOG),
+				a.log_guest_addr))
+			return -EINVAL;
+	}
+
+	vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
+	vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
+	vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
+	vq->log_addr = a.log_guest_addr;
+	vq->used = (void __user *)(unsigned long)a.used_user_addr;
+
+	return 0;
+}
+
+static long vhost_vring_set_num_addr(struct vhost_dev *d,
+				     struct vhost_virtqueue *vq,
+				     unsigned int ioctl,
+				     void __user *argp)
+{
+	long r;
+
+	mutex_lock(&vq->mutex);
+
+	switch (ioctl) {
+	case VHOST_SET_VRING_NUM:
+		r = vhost_vring_set_num(d, vq, argp);
+		break;
+	case VHOST_SET_VRING_ADDR:
+		r = vhost_vring_set_addr(d, vq, argp);
+		break;
+	default:
+		BUG();
+	}
+
+	mutex_unlock(&vq->mutex);
+
+	return r;
+}
+long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
+{
+	struct file *eventfp, *filep = NULL;
+	bool pollstart = false, pollstop = false;
+	struct eventfd_ctx *ctx = NULL;
+	struct vhost_virtqueue *vq;
+	struct vhost_vring_state s;
+	struct vhost_vring_file f;
+	u32 idx;
+	long r;
+
+	r = vhost_get_vq_from_user(d, argp, &vq, &idx);
+	if (r < 0)
+		return r;
+
+	if (ioctl == VHOST_SET_VRING_NUM ||
+	    ioctl == VHOST_SET_VRING_ADDR) {
+		return vhost_vring_set_num_addr(d, vq, ioctl, argp);
+	}
+
+	mutex_lock(&vq->mutex);
+
+	switch (ioctl) {
+	case VHOST_SET_VRING_BASE:
+		/* Moving base with an active backend?
+		 * You don't want to do that. */
+		if (vq->private_data) {
+			r = -EBUSY;
+			break;
+		}
+		if (copy_from_user(&s, argp, sizeof s)) {
+			r = -EFAULT;
+			break;
+		}
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+			vq->last_avail_idx = s.num & 0xffff;
+			vq->last_used_idx = (s.num >> 16) & 0xffff;
+		} else {
+			if (s.num > 0xffff) {
+				r = -EINVAL;
+				break;
+			}
+			vq->last_avail_idx = s.num;
+		}
+		/* Forget the cached index value. */
+		vq->avail_idx = vq->last_avail_idx;
+		break;
+	case VHOST_GET_VRING_BASE:
+		s.index = idx;
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+			s.num = (u32)vq->last_avail_idx | ((u32)vq->last_used_idx << 16);
+		else
+			s.num = vq->last_avail_idx;
+		if (copy_to_user(argp, &s, sizeof s))
+			r = -EFAULT;
+		break;
+	case VHOST_SET_VRING_KICK:
+		if (copy_from_user(&f, argp, sizeof f)) {
+			r = -EFAULT;
+			break;
+		}
+		eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
+		if (IS_ERR(eventfp)) {
+			r = PTR_ERR(eventfp);
+			break;
+		}
+		if (eventfp != vq->kick) {
+			pollstop = (filep = vq->kick) != NULL;
+			pollstart = (vq->kick = eventfp) != NULL;
+		} else
+			filep = eventfp;
+		break;
+	case VHOST_SET_VRING_CALL:
+		if (copy_from_user(&f, argp, sizeof f)) {
+			r = -EFAULT;
+			break;
+		}
+		ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
+		if (IS_ERR(ctx)) {
+			r = PTR_ERR(ctx);
+			break;
+		}
+
+		swap(ctx, vq->call_ctx.ctx);
+		break;
+	case VHOST_SET_VRING_ERR:
+		if (copy_from_user(&f, argp, sizeof f)) {
+			r = -EFAULT;
+			break;
+		}
+		ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
+		if (IS_ERR(ctx)) {
+			r = PTR_ERR(ctx);
+			break;
+		}
+		swap(ctx, vq->error_ctx);
+		break;
+	case VHOST_SET_VRING_ENDIAN:
+		r = vhost_set_vring_endian(vq, argp);
+		break;
+	case VHOST_GET_VRING_ENDIAN:
+		r = vhost_get_vring_endian(vq, idx, argp);
+		break;
+	case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
+		if (copy_from_user(&s, argp, sizeof(s))) {
+			r = -EFAULT;
+			break;
+		}
+		vq->busyloop_timeout = s.num;
+		break;
+	case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
+		s.index = idx;
+		s.num = vq->busyloop_timeout;
+		if (copy_to_user(argp, &s, sizeof(s)))
+			r = -EFAULT;
+		break;
+	default:
+		r = -ENOIOCTLCMD;
+	}
+
+	if (pollstop && vq->handle_kick)
+		vhost_poll_stop(&vq->poll);
+
+	if (!IS_ERR_OR_NULL(ctx))
+		eventfd_ctx_put(ctx);
+	if (filep)
+		fput(filep);
+
+	if (pollstart && vq->handle_kick)
+		r = vhost_poll_start(&vq->poll, vq->kick);
+
+	mutex_unlock(&vq->mutex);
+
+	if (pollstop && vq->handle_kick)
+		vhost_dev_flush(vq->poll.dev);
+	return r;
+}
+EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
+
+int vhost_init_device_iotlb(struct vhost_dev *d)
+{
+	struct vhost_iotlb *niotlb, *oiotlb;
+	int i;
+
+	niotlb = iotlb_alloc();
+	if (!niotlb)
+		return -ENOMEM;
+
+	oiotlb = d->iotlb;
+	d->iotlb = niotlb;
+
+	for (i = 0; i < d->nvqs; ++i) {
+		struct vhost_virtqueue *vq = d->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vq->iotlb = niotlb;
+		__vhost_vq_meta_reset(vq);
+		mutex_unlock(&vq->mutex);
+	}
+
+	vhost_iotlb_free(oiotlb);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
+
+/* Caller must have device mutex */
+long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
+{
+	struct eventfd_ctx *ctx;
+	u64 p;
+	long r;
+	int i, fd;
+
+	/* If you are not the owner, you can become one */
+	if (ioctl == VHOST_SET_OWNER) {
+		r = vhost_dev_set_owner(d);
+		goto done;
+	}
+
+	/* You must be the owner to do anything else */
+	r = vhost_dev_check_owner(d);
+	if (r)
+		goto done;
+
+	switch (ioctl) {
+	case VHOST_SET_MEM_TABLE:
+		r = vhost_set_memory(d, argp);
+		break;
+	case VHOST_SET_LOG_BASE:
+		if (copy_from_user(&p, argp, sizeof p)) {
+			r = -EFAULT;
+			break;
+		}
+		if ((u64)(unsigned long)p != p) {
+			r = -EFAULT;
+			break;
+		}
+		for (i = 0; i < d->nvqs; ++i) {
+			struct vhost_virtqueue *vq;
+			void __user *base = (void __user *)(unsigned long)p;
+			vq = d->vqs[i];
+			mutex_lock(&vq->mutex);
+			/* If ring is inactive, will check when it's enabled. */
+			if (vq->private_data && !vq_log_access_ok(vq, base))
+				r = -EFAULT;
+			else
+				vq->log_base = base;
+			mutex_unlock(&vq->mutex);
+		}
+		break;
+	case VHOST_SET_LOG_FD:
+		r = get_user(fd, (int __user *)argp);
+		if (r < 0)
+			break;
+		ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
+		if (IS_ERR(ctx)) {
+			r = PTR_ERR(ctx);
+			break;
+		}
+		swap(ctx, d->log_ctx);
+		for (i = 0; i < d->nvqs; ++i) {
+			mutex_lock(&d->vqs[i]->mutex);
+			d->vqs[i]->log_ctx = d->log_ctx;
+			mutex_unlock(&d->vqs[i]->mutex);
+		}
+		if (ctx)
+			eventfd_ctx_put(ctx);
+		break;
+	default:
+		r = -ENOIOCTLCMD;
+		break;
+	}
+done:
+	return r;
+}
+EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
+
+/* TODO: This is really inefficient.  We need something like get_user()
+ * (instruction directly accesses the data, with an exception table entry
+ * returning -EFAULT). See Documentation/arch/x86/exception-tables.rst.
+ */
+static int set_bit_to_user(int nr, void __user *addr)
+{
+	unsigned long log = (unsigned long)addr;
+	struct page *page;
+	void *base;
+	int bit = nr + (log % PAGE_SIZE) * 8;
+	int r;
+
+	r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page);
+	if (r < 0)
+		return r;
+	BUG_ON(r != 1);
+	base = kmap_atomic(page);
+	set_bit(bit, base);
+	kunmap_atomic(base);
+	unpin_user_pages_dirty_lock(&page, 1, true);
+	return 0;
+}
+
+static int log_write(void __user *log_base,
+		     u64 write_address, u64 write_length)
+{
+	u64 write_page = write_address / VHOST_PAGE_SIZE;
+	int r;
+
+	if (!write_length)
+		return 0;
+	write_length += write_address % VHOST_PAGE_SIZE;
+	for (;;) {
+		u64 base = (u64)(unsigned long)log_base;
+		u64 log = base + write_page / 8;
+		int bit = write_page % 8;
+		if ((u64)(unsigned long)log != log)
+			return -EFAULT;
+		r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
+		if (r < 0)
+			return r;
+		if (write_length <= VHOST_PAGE_SIZE)
+			break;
+		write_length -= VHOST_PAGE_SIZE;
+		write_page += 1;
+	}
+	return r;
+}
+
+static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
+{
+	struct vhost_iotlb *umem = vq->umem;
+	struct vhost_iotlb_map *u;
+	u64 start, end, l, min;
+	int r;
+	bool hit = false;
+
+	while (len) {
+		min = len;
+		/* More than one GPAs can be mapped into a single HVA. So
+		 * iterate all possible umems here to be safe.
+		 */
+		list_for_each_entry(u, &umem->list, link) {
+			if (u->addr > hva - 1 + len ||
+			    u->addr - 1 + u->size < hva)
+				continue;
+			start = max(u->addr, hva);
+			end = min(u->addr - 1 + u->size, hva - 1 + len);
+			l = end - start + 1;
+			r = log_write(vq->log_base,
+				      u->start + start - u->addr,
+				      l);
+			if (r < 0)
+				return r;
+			hit = true;
+			min = min(l, min);
+		}
+
+		if (!hit)
+			return -EFAULT;
+
+		len -= min;
+		hva += min;
+	}
+
+	return 0;
+}
+
+static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
+{
+	struct iovec *iov = vq->log_iov;
+	int i, ret;
+
+	if (!vq->iotlb)
+		return log_write(vq->log_base, vq->log_addr + used_offset, len);
+
+	ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
+			     len, iov, 64, VHOST_ACCESS_WO);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < ret; i++) {
+		ret = log_write_hva(vq,	(uintptr_t)iov[i].iov_base,
+				    iov[i].iov_len);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
+		    unsigned int log_num, u64 len, struct iovec *iov, int count)
+{
+	int i, r;
+
+	/* Make sure data written is seen before log. */
+	smp_wmb();
+
+	if (vq->iotlb) {
+		for (i = 0; i < count; i++) {
+			r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
+					  iov[i].iov_len);
+			if (r < 0)
+				return r;
+		}
+		return 0;
+	}
+
+	for (i = 0; i < log_num; ++i) {
+		u64 l = min(log[i].len, len);
+		r = log_write(vq->log_base, log[i].addr, l);
+		if (r < 0)
+			return r;
+		len -= l;
+		if (!len) {
+			if (vq->log_ctx)
+				eventfd_signal(vq->log_ctx, 1);
+			return 0;
+		}
+	}
+	/* Length written exceeds what we have stored. This is a bug. */
+	BUG();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_log_write);
+
+static int vhost_update_used_flags(struct vhost_virtqueue *vq)
+{
+	void __user *used;
+	if (vhost_put_used_flags(vq))
+		return -EFAULT;
+	if (unlikely(vq->log_used)) {
+		/* Make sure the flag is seen before log. */
+		smp_wmb();
+		/* Log used flag write. */
+		used = &vq->used->flags;
+		log_used(vq, (used - (void __user *)vq->used),
+			 sizeof vq->used->flags);
+		if (vq->log_ctx)
+			eventfd_signal(vq->log_ctx, 1);
+	}
+	return 0;
+}
+
+static int vhost_update_avail_event(struct vhost_virtqueue *vq)
+{
+	if (vhost_put_avail_event(vq))
+		return -EFAULT;
+	if (unlikely(vq->log_used)) {
+		void __user *used;
+		/* Make sure the event is seen before log. */
+		smp_wmb();
+		/* Log avail event write */
+		used = vhost_avail_event(vq);
+		log_used(vq, (used - (void __user *)vq->used),
+			 sizeof *vhost_avail_event(vq));
+		if (vq->log_ctx)
+			eventfd_signal(vq->log_ctx, 1);
+	}
+	return 0;
+}
+
+int vhost_vq_init_access(struct vhost_virtqueue *vq)
+{
+	__virtio16 last_used_idx;
+	int r;
+	bool is_le = vq->is_le;
+
+	if (!vq->private_data)
+		return 0;
+
+	vhost_init_is_le(vq);
+
+	r = vhost_update_used_flags(vq);
+	if (r)
+		goto err;
+	vq->signalled_used_valid = false;
+	if (!vq->iotlb &&
+	    !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
+		r = -EFAULT;
+		goto err;
+	}
+	r = vhost_get_used_idx(vq, &last_used_idx);
+	if (r) {
+		vq_err(vq, "Can't access used idx at %p\n",
+		       &vq->used->idx);
+		goto err;
+	}
+	vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
+	return 0;
+
+err:
+	vq->is_le = is_le;
+	return r;
+}
+EXPORT_SYMBOL_GPL(vhost_vq_init_access);
+
+static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
+			  struct iovec iov[], int iov_size, int access)
+{
+	const struct vhost_iotlb_map *map;
+	struct vhost_dev *dev = vq->dev;
+	struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
+	struct iovec *_iov;
+	u64 s = 0, last = addr + len - 1;
+	int ret = 0;
+
+	while ((u64)len > s) {
+		u64 size;
+		if (unlikely(ret >= iov_size)) {
+			ret = -ENOBUFS;
+			break;
+		}
+
+		map = vhost_iotlb_itree_first(umem, addr, last);
+		if (map == NULL || map->start > addr) {
+			if (umem != dev->iotlb) {
+				ret = -EFAULT;
+				break;
+			}
+			ret = -EAGAIN;
+			break;
+		} else if (!(map->perm & access)) {
+			ret = -EPERM;
+			break;
+		}
+
+		_iov = iov + ret;
+		size = map->size - addr + map->start;
+		_iov->iov_len = min((u64)len - s, size);
+		_iov->iov_base = (void __user *)(unsigned long)
+				 (map->addr + addr - map->start);
+		s += size;
+		addr += size;
+		++ret;
+	}
+
+	if (ret == -EAGAIN)
+		vhost_iotlb_miss(vq, addr, access);
+	return ret;
+}
+
+/* Each buffer in the virtqueues is actually a chain of descriptors.  This
+ * function returns the next descriptor in the chain,
+ * or -1U if we're at the end. */
+static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
+{
+	unsigned int next;
+
+	/* If this descriptor says it doesn't chain, we're done. */
+	if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
+		return -1U;
+
+	/* Check they're not leading us off end of descriptors. */
+	next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
+	return next;
+}
+
+static int get_indirect(struct vhost_virtqueue *vq,
+			struct iovec iov[], unsigned int iov_size,
+			unsigned int *out_num, unsigned int *in_num,
+			struct vhost_log *log, unsigned int *log_num,
+			struct vring_desc *indirect)
+{
+	struct vring_desc desc;
+	unsigned int i = 0, count, found = 0;
+	u32 len = vhost32_to_cpu(vq, indirect->len);
+	struct iov_iter from;
+	int ret, access;
+
+	/* Sanity check */
+	if (unlikely(len % sizeof desc)) {
+		vq_err(vq, "Invalid length in indirect descriptor: "
+		       "len 0x%llx not multiple of 0x%zx\n",
+		       (unsigned long long)len,
+		       sizeof desc);
+		return -EINVAL;
+	}
+
+	ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
+			     UIO_MAXIOV, VHOST_ACCESS_RO);
+	if (unlikely(ret < 0)) {
+		if (ret != -EAGAIN)
+			vq_err(vq, "Translation failure %d in indirect.\n", ret);
+		return ret;
+	}
+	iov_iter_init(&from, ITER_SOURCE, vq->indirect, ret, len);
+	count = len / sizeof desc;
+	/* Buffers are chained via a 16 bit next field, so
+	 * we can have at most 2^16 of these. */
+	if (unlikely(count > USHRT_MAX + 1)) {
+		vq_err(vq, "Indirect buffer length too big: %d\n",
+		       indirect->len);
+		return -E2BIG;
+	}
+
+	do {
+		unsigned iov_count = *in_num + *out_num;
+		if (unlikely(++found > count)) {
+			vq_err(vq, "Loop detected: last one at %u "
+			       "indirect size %u\n",
+			       i, count);
+			return -EINVAL;
+		}
+		if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
+			vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
+			       i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
+			return -EINVAL;
+		}
+		if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
+			vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
+			       i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
+			return -EINVAL;
+		}
+
+		if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
+			access = VHOST_ACCESS_WO;
+		else
+			access = VHOST_ACCESS_RO;
+
+		ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
+				     vhost32_to_cpu(vq, desc.len), iov + iov_count,
+				     iov_size - iov_count, access);
+		if (unlikely(ret < 0)) {
+			if (ret != -EAGAIN)
+				vq_err(vq, "Translation failure %d indirect idx %d\n",
+					ret, i);
+			return ret;
+		}
+		/* If this is an input descriptor, increment that count. */
+		if (access == VHOST_ACCESS_WO) {
+			*in_num += ret;
+			if (unlikely(log && ret)) {
+				log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
+				log[*log_num].len = vhost32_to_cpu(vq, desc.len);
+				++*log_num;
+			}
+		} else {
+			/* If it's an output descriptor, they're all supposed
+			 * to come before any input descriptors. */
+			if (unlikely(*in_num)) {
+				vq_err(vq, "Indirect descriptor "
+				       "has out after in: idx %d\n", i);
+				return -EINVAL;
+			}
+			*out_num += ret;
+		}
+	} while ((i = next_desc(vq, &desc)) != -1);
+	return 0;
+}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access.  Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found.  A negative code is
+ * returned on error. */
+int vhost_get_vq_desc(struct vhost_virtqueue *vq,
+		      struct iovec iov[], unsigned int iov_size,
+		      unsigned int *out_num, unsigned int *in_num,
+		      struct vhost_log *log, unsigned int *log_num)
+{
+	struct vring_desc desc;
+	unsigned int i, head, found = 0;
+	u16 last_avail_idx;
+	__virtio16 avail_idx;
+	__virtio16 ring_head;
+	int ret, access;
+
+	/* Check it isn't doing very strange things with descriptor numbers. */
+	last_avail_idx = vq->last_avail_idx;
+
+	if (vq->avail_idx == vq->last_avail_idx) {
+		if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
+			vq_err(vq, "Failed to access avail idx at %p\n",
+				&vq->avail->idx);
+			return -EFAULT;
+		}
+		vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
+
+		if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
+			vq_err(vq, "Guest moved used index from %u to %u",
+				last_avail_idx, vq->avail_idx);
+			return -EFAULT;
+		}
+
+		/* If there's nothing new since last we looked, return
+		 * invalid.
+		 */
+		if (vq->avail_idx == last_avail_idx)
+			return vq->num;
+
+		/* Only get avail ring entries after they have been
+		 * exposed by guest.
+		 */
+		smp_rmb();
+	}
+
+	/* Grab the next descriptor number they're advertising, and increment
+	 * the index we've seen. */
+	if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
+		vq_err(vq, "Failed to read head: idx %d address %p\n",
+		       last_avail_idx,
+		       &vq->avail->ring[last_avail_idx % vq->num]);
+		return -EFAULT;
+	}
+
+	head = vhost16_to_cpu(vq, ring_head);
+
+	/* If their number is silly, that's an error. */
+	if (unlikely(head >= vq->num)) {
+		vq_err(vq, "Guest says index %u > %u is available",
+		       head, vq->num);
+		return -EINVAL;
+	}
+
+	/* When we start there are none of either input nor output. */
+	*out_num = *in_num = 0;
+	if (unlikely(log))
+		*log_num = 0;
+
+	i = head;
+	do {
+		unsigned iov_count = *in_num + *out_num;
+		if (unlikely(i >= vq->num)) {
+			vq_err(vq, "Desc index is %u > %u, head = %u",
+			       i, vq->num, head);
+			return -EINVAL;
+		}
+		if (unlikely(++found > vq->num)) {
+			vq_err(vq, "Loop detected: last one at %u "
+			       "vq size %u head %u\n",
+			       i, vq->num, head);
+			return -EINVAL;
+		}
+		ret = vhost_get_desc(vq, &desc, i);
+		if (unlikely(ret)) {
+			vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
+			       i, vq->desc + i);
+			return -EFAULT;
+		}
+		if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
+			ret = get_indirect(vq, iov, iov_size,
+					   out_num, in_num,
+					   log, log_num, &desc);
+			if (unlikely(ret < 0)) {
+				if (ret != -EAGAIN)
+					vq_err(vq, "Failure detected "
+						"in indirect descriptor at idx %d\n", i);
+				return ret;
+			}
+			continue;
+		}
+
+		if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
+			access = VHOST_ACCESS_WO;
+		else
+			access = VHOST_ACCESS_RO;
+		ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
+				     vhost32_to_cpu(vq, desc.len), iov + iov_count,
+				     iov_size - iov_count, access);
+		if (unlikely(ret < 0)) {
+			if (ret != -EAGAIN)
+				vq_err(vq, "Translation failure %d descriptor idx %d\n",
+					ret, i);
+			return ret;
+		}
+		if (access == VHOST_ACCESS_WO) {
+			/* If this is an input descriptor,
+			 * increment that count. */
+			*in_num += ret;
+			if (unlikely(log && ret)) {
+				log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
+				log[*log_num].len = vhost32_to_cpu(vq, desc.len);
+				++*log_num;
+			}
+		} else {
+			/* If it's an output descriptor, they're all supposed
+			 * to come before any input descriptors. */
+			if (unlikely(*in_num)) {
+				vq_err(vq, "Descriptor has out after in: "
+				       "idx %d\n", i);
+				return -EINVAL;
+			}
+			*out_num += ret;
+		}
+	} while ((i = next_desc(vq, &desc)) != -1);
+
+	/* On success, increment avail index. */
+	vq->last_avail_idx++;
+
+	/* Assume notifications from guest are disabled at this point,
+	 * if they aren't we would need to update avail_event index. */
+	BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
+	return head;
+}
+EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
+
+/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
+void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
+{
+	vq->last_avail_idx -= n;
+}
+EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
+
+/* After we've used one of their buffers, we tell them about it.  We'll then
+ * want to notify the guest, using eventfd. */
+int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
+{
+	struct vring_used_elem heads = {
+		cpu_to_vhost32(vq, head),
+		cpu_to_vhost32(vq, len)
+	};
+
+	return vhost_add_used_n(vq, &heads, 1);
+}
+EXPORT_SYMBOL_GPL(vhost_add_used);
+
+static int __vhost_add_used_n(struct vhost_virtqueue *vq,
+			    struct vring_used_elem *heads,
+			    unsigned count)
+{
+	vring_used_elem_t __user *used;
+	u16 old, new;
+	int start;
+
+	start = vq->last_used_idx & (vq->num - 1);
+	used = vq->used->ring + start;
+	if (vhost_put_used(vq, heads, start, count)) {
+		vq_err(vq, "Failed to write used");
+		return -EFAULT;
+	}
+	if (unlikely(vq->log_used)) {
+		/* Make sure data is seen before log. */
+		smp_wmb();
+		/* Log used ring entry write. */
+		log_used(vq, ((void __user *)used - (void __user *)vq->used),
+			 count * sizeof *used);
+	}
+	old = vq->last_used_idx;
+	new = (vq->last_used_idx += count);
+	/* If the driver never bothers to signal in a very long while,
+	 * used index might wrap around. If that happens, invalidate
+	 * signalled_used index we stored. TODO: make sure driver
+	 * signals at least once in 2^16 and remove this. */
+	if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
+		vq->signalled_used_valid = false;
+	return 0;
+}
+
+/* After we've used one of their buffers, we tell them about it.  We'll then
+ * want to notify the guest, using eventfd. */
+int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
+		     unsigned count)
+{
+	int start, n, r;
+
+	start = vq->last_used_idx & (vq->num - 1);
+	n = vq->num - start;
+	if (n < count) {
+		r = __vhost_add_used_n(vq, heads, n);
+		if (r < 0)
+			return r;
+		heads += n;
+		count -= n;
+	}
+	r = __vhost_add_used_n(vq, heads, count);
+
+	/* Make sure buffer is written before we update index. */
+	smp_wmb();
+	if (vhost_put_used_idx(vq)) {
+		vq_err(vq, "Failed to increment used idx");
+		return -EFAULT;
+	}
+	if (unlikely(vq->log_used)) {
+		/* Make sure used idx is seen before log. */
+		smp_wmb();
+		/* Log used index update. */
+		log_used(vq, offsetof(struct vring_used, idx),
+			 sizeof vq->used->idx);
+		if (vq->log_ctx)
+			eventfd_signal(vq->log_ctx, 1);
+	}
+	return r;
+}
+EXPORT_SYMBOL_GPL(vhost_add_used_n);
+
+static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+	__u16 old, new;
+	__virtio16 event;
+	bool v;
+	/* Flush out used index updates. This is paired
+	 * with the barrier that the Guest executes when enabling
+	 * interrupts. */
+	smp_mb();
+
+	if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
+	    unlikely(vq->avail_idx == vq->last_avail_idx))
+		return true;
+
+	if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
+		__virtio16 flags;
+		if (vhost_get_avail_flags(vq, &flags)) {
+			vq_err(vq, "Failed to get flags");
+			return true;
+		}
+		return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
+	}
+	old = vq->signalled_used;
+	v = vq->signalled_used_valid;
+	new = vq->signalled_used = vq->last_used_idx;
+	vq->signalled_used_valid = true;
+
+	if (unlikely(!v))
+		return true;
+
+	if (vhost_get_used_event(vq, &event)) {
+		vq_err(vq, "Failed to get used event idx");
+		return true;
+	}
+	return vring_need_event(vhost16_to_cpu(vq, event), new, old);
+}
+
+/* This actually signals the guest, using eventfd. */
+void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+	/* Signal the Guest tell them we used something up. */
+	if (vq->call_ctx.ctx && vhost_notify(dev, vq))
+		eventfd_signal(vq->call_ctx.ctx, 1);
+}
+EXPORT_SYMBOL_GPL(vhost_signal);
+
+/* And here's the combo meal deal.  Supersize me! */
+void vhost_add_used_and_signal(struct vhost_dev *dev,
+			       struct vhost_virtqueue *vq,
+			       unsigned int head, int len)
+{
+	vhost_add_used(vq, head, len);
+	vhost_signal(dev, vq);
+}
+EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
+
+/* multi-buffer version of vhost_add_used_and_signal */
+void vhost_add_used_and_signal_n(struct vhost_dev *dev,
+				 struct vhost_virtqueue *vq,
+				 struct vring_used_elem *heads, unsigned count)
+{
+	vhost_add_used_n(vq, heads, count);
+	vhost_signal(dev, vq);
+}
+EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
+
+/* return true if we're sure that avaiable ring is empty */
+bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+	__virtio16 avail_idx;
+	int r;
+
+	if (vq->avail_idx != vq->last_avail_idx)
+		return false;
+
+	r = vhost_get_avail_idx(vq, &avail_idx);
+	if (unlikely(r))
+		return false;
+	vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
+
+	return vq->avail_idx == vq->last_avail_idx;
+}
+EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
+
+/* OK, now we need to know about added descriptors. */
+bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+	__virtio16 avail_idx;
+	int r;
+
+	if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
+		return false;
+	vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
+	if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
+		r = vhost_update_used_flags(vq);
+		if (r) {
+			vq_err(vq, "Failed to enable notification at %p: %d\n",
+			       &vq->used->flags, r);
+			return false;
+		}
+	} else {
+		r = vhost_update_avail_event(vq);
+		if (r) {
+			vq_err(vq, "Failed to update avail event index at %p: %d\n",
+			       vhost_avail_event(vq), r);
+			return false;
+		}
+	}
+	/* They could have slipped one in as we were doing that: make
+	 * sure it's written, then check again. */
+	smp_mb();
+	r = vhost_get_avail_idx(vq, &avail_idx);
+	if (r) {
+		vq_err(vq, "Failed to check avail idx at %p: %d\n",
+		       &vq->avail->idx, r);
+		return false;
+	}
+	vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
+
+	return vq->avail_idx != vq->last_avail_idx;
+}
+EXPORT_SYMBOL_GPL(vhost_enable_notify);
+
+/* We don't need to be notified again. */
+void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+	int r;
+
+	if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
+		return;
+	vq->used_flags |= VRING_USED_F_NO_NOTIFY;
+	if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
+		r = vhost_update_used_flags(vq);
+		if (r)
+			vq_err(vq, "Failed to disable notification at %p: %d\n",
+			       &vq->used->flags, r);
+	}
+}
+EXPORT_SYMBOL_GPL(vhost_disable_notify);
+
+/* Create a new message. */
+struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
+{
+	/* Make sure all padding within the structure is initialized. */
+	struct vhost_msg_node *node = kzalloc(sizeof(*node), GFP_KERNEL);
+	if (!node)
+		return NULL;
+
+	node->vq = vq;
+	node->msg.type = type;
+	return node;
+}
+EXPORT_SYMBOL_GPL(vhost_new_msg);
+
+void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
+		       struct vhost_msg_node *node)
+{
+	spin_lock(&dev->iotlb_lock);
+	list_add_tail(&node->node, head);
+	spin_unlock(&dev->iotlb_lock);
+
+	wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
+}
+EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
+
+struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
+					 struct list_head *head)
+{
+	struct vhost_msg_node *node = NULL;
+
+	spin_lock(&dev->iotlb_lock);
+	if (!list_empty(head)) {
+		node = list_first_entry(head, struct vhost_msg_node,
+					node);
+		list_del(&node->node);
+	}
+	spin_unlock(&dev->iotlb_lock);
+
+	return node;
+}
+EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
+
+void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
+{
+	struct vhost_virtqueue *vq;
+	int i;
+
+	mutex_lock(&dev->mutex);
+	for (i = 0; i < dev->nvqs; ++i) {
+		vq = dev->vqs[i];
+		mutex_lock(&vq->mutex);
+		vq->acked_backend_features = features;
+		mutex_unlock(&vq->mutex);
+	}
+	mutex_unlock(&dev->mutex);
+}
+EXPORT_SYMBOL_GPL(vhost_set_backend_features);
+
+static int __init vhost_init(void)
+{
+	return 0;
+}
+
+static void __exit vhost_exit(void)
+{
+}
+
+module_init(vhost_init);
+module_exit(vhost_exit);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Michael S. Tsirkin");
+MODULE_DESCRIPTION("Host kernel accelerator for virtio");
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
new file mode 100644
index 000000000..f60d5f7be
--- /dev/null
+++ b/drivers/vhost/vhost.h
@@ -0,0 +1,343 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _VHOST_H
+#define _VHOST_H
+
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+#include <linux/atomic.h>
+#include <linux/vhost_iotlb.h>
+#include <linux/irqbypass.h>
+
+struct vhost_work;
+struct vhost_task;
+typedef void (*vhost_work_fn_t)(struct vhost_work *work);
+
+#define VHOST_WORK_QUEUED 1
+struct vhost_work {
+	struct llist_node	node;
+	vhost_work_fn_t		fn;
+	unsigned long		flags;
+};
+
+struct vhost_worker {
+	struct vhost_task	*vtsk;
+	/* Used to serialize device wide flushing with worker swapping. */
+	struct mutex		mutex;
+	struct llist_head	work_list;
+	u64			kcov_handle;
+	u32			id;
+	int			attachment_cnt;
+};
+
+/* Poll a file (eventfd or socket) */
+/* Note: there's nothing vhost specific about this structure. */
+struct vhost_poll {
+	poll_table		table;
+	wait_queue_head_t	*wqh;
+	wait_queue_entry_t	wait;
+	struct vhost_work	work;
+	__poll_t		mask;
+	struct vhost_dev	*dev;
+	struct vhost_virtqueue	*vq;
+};
+
+void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
+		     __poll_t mask, struct vhost_dev *dev,
+		     struct vhost_virtqueue *vq);
+int vhost_poll_start(struct vhost_poll *poll, struct file *file);
+void vhost_poll_stop(struct vhost_poll *poll);
+void vhost_poll_queue(struct vhost_poll *poll);
+
+void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
+void vhost_dev_flush(struct vhost_dev *dev);
+
+struct vhost_log {
+	u64 addr;
+	u64 len;
+};
+
+enum vhost_uaddr_type {
+	VHOST_ADDR_DESC = 0,
+	VHOST_ADDR_AVAIL = 1,
+	VHOST_ADDR_USED = 2,
+	VHOST_NUM_ADDRS = 3,
+};
+
+struct vhost_vring_call {
+	struct eventfd_ctx *ctx;
+	struct irq_bypass_producer producer;
+};
+
+/* The virtqueue structure describes a queue attached to a device. */
+struct vhost_virtqueue {
+	struct vhost_dev *dev;
+	struct vhost_worker __rcu *worker;
+
+	/* The actual ring of buffers. */
+	struct mutex mutex;
+	unsigned int num;
+	vring_desc_t __user *desc;
+	vring_avail_t __user *avail;
+	vring_used_t __user *used;
+	const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS];
+	struct file *kick;
+	struct vhost_vring_call call_ctx;
+	struct eventfd_ctx *error_ctx;
+	struct eventfd_ctx *log_ctx;
+
+	struct vhost_poll poll;
+
+	/* The routine to call when the Guest pings us, or timeout. */
+	vhost_work_fn_t handle_kick;
+
+	/* Last available index we saw.
+	 * Values are limited to 0x7fff, and the high bit is used as
+	 * a wrap counter when using VIRTIO_F_RING_PACKED. */
+	u16 last_avail_idx;
+
+	/* Caches available index value from user. */
+	u16 avail_idx;
+
+	/* Last index we used.
+	 * Values are limited to 0x7fff, and the high bit is used as
+	 * a wrap counter when using VIRTIO_F_RING_PACKED. */
+	u16 last_used_idx;
+
+	/* Used flags */
+	u16 used_flags;
+
+	/* Last used index value we have signalled on */
+	u16 signalled_used;
+
+	/* Last used index value we have signalled on */
+	bool signalled_used_valid;
+
+	/* Log writes to used structure. */
+	bool log_used;
+	u64 log_addr;
+
+	struct iovec iov[UIO_MAXIOV];
+	struct iovec iotlb_iov[64];
+	struct iovec *indirect;
+	struct vring_used_elem *heads;
+	/* Protected by virtqueue mutex. */
+	struct vhost_iotlb *umem;
+	struct vhost_iotlb *iotlb;
+	void *private_data;
+	u64 acked_features;
+	u64 acked_backend_features;
+	/* Log write descriptors */
+	void __user *log_base;
+	struct vhost_log *log;
+	struct iovec log_iov[64];
+
+	/* Ring endianness. Defaults to legacy native endianness.
+	 * Set to true when starting a modern virtio device. */
+	bool is_le;
+#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
+	/* Ring endianness requested by userspace for cross-endian support. */
+	bool user_be;
+#endif
+	u32 busyloop_timeout;
+};
+
+struct vhost_msg_node {
+  union {
+	  struct vhost_msg msg;
+	  struct vhost_msg_v2 msg_v2;
+  };
+  struct vhost_virtqueue *vq;
+  struct list_head node;
+};
+
+struct vhost_dev {
+	struct mm_struct *mm;
+	struct mutex mutex;
+	struct vhost_virtqueue **vqs;
+	int nvqs;
+	struct eventfd_ctx *log_ctx;
+	struct vhost_iotlb *umem;
+	struct vhost_iotlb *iotlb;
+	spinlock_t iotlb_lock;
+	struct list_head read_list;
+	struct list_head pending_list;
+	wait_queue_head_t wait;
+	int iov_limit;
+	int weight;
+	int byte_weight;
+	struct xarray worker_xa;
+	bool use_worker;
+	int (*msg_handler)(struct vhost_dev *dev, u32 asid,
+			   struct vhost_iotlb_msg *msg);
+};
+
+bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);
+void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
+		    int nvqs, int iov_limit, int weight, int byte_weight,
+		    bool use_worker,
+		    int (*msg_handler)(struct vhost_dev *dev, u32 asid,
+				       struct vhost_iotlb_msg *msg));
+long vhost_dev_set_owner(struct vhost_dev *dev);
+bool vhost_dev_has_owner(struct vhost_dev *dev);
+long vhost_dev_check_owner(struct vhost_dev *);
+struct vhost_iotlb *vhost_dev_reset_owner_prepare(void);
+void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *iotlb);
+void vhost_dev_cleanup(struct vhost_dev *);
+void vhost_dev_stop(struct vhost_dev *);
+long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
+long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp);
+long vhost_worker_ioctl(struct vhost_dev *dev, unsigned int ioctl,
+			void __user *argp);
+bool vhost_vq_access_ok(struct vhost_virtqueue *vq);
+bool vhost_log_access_ok(struct vhost_dev *);
+void vhost_clear_msg(struct vhost_dev *dev);
+
+int vhost_get_vq_desc(struct vhost_virtqueue *,
+		      struct iovec iov[], unsigned int iov_size,
+		      unsigned int *out_num, unsigned int *in_num,
+		      struct vhost_log *log, unsigned int *log_num);
+void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
+
+void vhost_vq_flush(struct vhost_virtqueue *vq);
+bool vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work);
+bool vhost_vq_has_work(struct vhost_virtqueue *vq);
+bool vhost_vq_is_setup(struct vhost_virtqueue *vq);
+int vhost_vq_init_access(struct vhost_virtqueue *);
+int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
+int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
+		     unsigned count);
+void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
+			       unsigned int id, int len);
+void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
+			       struct vring_used_elem *heads, unsigned count);
+void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
+void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
+bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *);
+bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
+
+int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
+		    unsigned int log_num, u64 len,
+		    struct iovec *iov, int count);
+int vq_meta_prefetch(struct vhost_virtqueue *vq);
+
+struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type);
+void vhost_enqueue_msg(struct vhost_dev *dev,
+		       struct list_head *head,
+		       struct vhost_msg_node *node);
+struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
+					 struct list_head *head);
+void vhost_set_backend_features(struct vhost_dev *dev, u64 features);
+
+__poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
+			    poll_table *wait);
+ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
+			    int noblock);
+ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
+			     struct iov_iter *from);
+int vhost_init_device_iotlb(struct vhost_dev *d);
+
+void vhost_iotlb_map_free(struct vhost_iotlb *iotlb,
+			  struct vhost_iotlb_map *map);
+
+#define vq_err(vq, fmt, ...) do {                                  \
+		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
+		if ((vq)->error_ctx)                               \
+				eventfd_signal((vq)->error_ctx, 1);\
+	} while (0)
+
+enum {
+	VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
+			 (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
+			 (1ULL << VIRTIO_RING_F_EVENT_IDX) |
+			 (1ULL << VHOST_F_LOG_ALL) |
+			 (1ULL << VIRTIO_F_ANY_LAYOUT) |
+			 (1ULL << VIRTIO_F_VERSION_1)
+};
+
+/**
+ * vhost_vq_set_backend - Set backend.
+ *
+ * @vq            Virtqueue.
+ * @private_data  The private data.
+ *
+ * Context: Need to call with vq->mutex acquired.
+ */
+static inline void vhost_vq_set_backend(struct vhost_virtqueue *vq,
+					void *private_data)
+{
+	vq->private_data = private_data;
+}
+
+/**
+ * vhost_vq_get_backend - Get backend.
+ *
+ * @vq            Virtqueue.
+ *
+ * Context: Need to call with vq->mutex acquired.
+ * Return: Private data previously set with vhost_vq_set_backend.
+ */
+static inline void *vhost_vq_get_backend(struct vhost_virtqueue *vq)
+{
+	return vq->private_data;
+}
+
+static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit)
+{
+	return vq->acked_features & (1ULL << bit);
+}
+
+static inline bool vhost_backend_has_feature(struct vhost_virtqueue *vq, int bit)
+{
+	return vq->acked_backend_features & (1ULL << bit);
+}
+
+#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
+static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
+{
+	return vq->is_le;
+}
+#else
+static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
+{
+	return virtio_legacy_is_little_endian() || vq->is_le;
+}
+#endif
+
+/* Memory accessors */
+static inline u16 vhost16_to_cpu(struct vhost_virtqueue *vq, __virtio16 val)
+{
+	return __virtio16_to_cpu(vhost_is_little_endian(vq), val);
+}
+
+static inline __virtio16 cpu_to_vhost16(struct vhost_virtqueue *vq, u16 val)
+{
+	return __cpu_to_virtio16(vhost_is_little_endian(vq), val);
+}
+
+static inline u32 vhost32_to_cpu(struct vhost_virtqueue *vq, __virtio32 val)
+{
+	return __virtio32_to_cpu(vhost_is_little_endian(vq), val);
+}
+
+static inline __virtio32 cpu_to_vhost32(struct vhost_virtqueue *vq, u32 val)
+{
+	return __cpu_to_virtio32(vhost_is_little_endian(vq), val);
+}
+
+static inline u64 vhost64_to_cpu(struct vhost_virtqueue *vq, __virtio64 val)
+{
+	return __virtio64_to_cpu(vhost_is_little_endian(vq), val);
+}
+
+static inline __virtio64 cpu_to_vhost64(struct vhost_virtqueue *vq, u64 val)
+{
+	return __cpu_to_virtio64(vhost_is_little_endian(vq), val);
+}
+#endif
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
new file mode 100644
index 000000000..7b8fd977f
--- /dev/null
+++ b/drivers/vhost/vringh.c
@@ -0,0 +1,1617 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Helpers for the host side of a virtio ring.
+ *
+ * Since these may be in userspace, we use (inline) accessors.
+ */
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/vringh.h>
+#include <linux/virtio_ring.h>
+#include <linux/kernel.h>
+#include <linux/ratelimit.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
+#include <linux/bvec.h>
+#include <linux/highmem.h>
+#include <linux/vhost_iotlb.h>
+#endif
+#include <uapi/linux/virtio_config.h>
+
+static __printf(1,2) __cold void vringh_bad(const char *fmt, ...)
+{
+	static DEFINE_RATELIMIT_STATE(vringh_rs,
+				      DEFAULT_RATELIMIT_INTERVAL,
+				      DEFAULT_RATELIMIT_BURST);
+	if (__ratelimit(&vringh_rs)) {
+		va_list ap;
+		va_start(ap, fmt);
+		printk(KERN_NOTICE "vringh:");
+		vprintk(fmt, ap);
+		va_end(ap);
+	}
+}
+
+/* Returns vring->num if empty, -ve on error. */
+static inline int __vringh_get_head(const struct vringh *vrh,
+				    int (*getu16)(const struct vringh *vrh,
+						  u16 *val, const __virtio16 *p),
+				    u16 *last_avail_idx)
+{
+	u16 avail_idx, i, head;
+	int err;
+
+	err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);
+	if (err) {
+		vringh_bad("Failed to access avail idx at %p",
+			   &vrh->vring.avail->idx);
+		return err;
+	}
+
+	if (*last_avail_idx == avail_idx)
+		return vrh->vring.num;
+
+	/* Only get avail ring entries after they have been exposed by guest. */
+	virtio_rmb(vrh->weak_barriers);
+
+	i = *last_avail_idx & (vrh->vring.num - 1);
+
+	err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);
+	if (err) {
+		vringh_bad("Failed to read head: idx %d address %p",
+			   *last_avail_idx, &vrh->vring.avail->ring[i]);
+		return err;
+	}
+
+	if (head >= vrh->vring.num) {
+		vringh_bad("Guest says index %u > %u is available",
+			   head, vrh->vring.num);
+		return -EINVAL;
+	}
+
+	(*last_avail_idx)++;
+	return head;
+}
+
+/**
+ * vringh_kiov_advance - skip bytes from vring_kiov
+ * @iov: an iov passed to vringh_getdesc_*() (updated as we consume)
+ * @len: the maximum length to advance
+ */
+void vringh_kiov_advance(struct vringh_kiov *iov, size_t len)
+{
+	while (len && iov->i < iov->used) {
+		size_t partlen = min(iov->iov[iov->i].iov_len, len);
+
+		iov->consumed += partlen;
+		iov->iov[iov->i].iov_len -= partlen;
+		iov->iov[iov->i].iov_base += partlen;
+
+		if (!iov->iov[iov->i].iov_len) {
+			/* Fix up old iov element then increment. */
+			iov->iov[iov->i].iov_len = iov->consumed;
+			iov->iov[iov->i].iov_base -= iov->consumed;
+
+			iov->consumed = 0;
+			iov->i++;
+		}
+
+		len -= partlen;
+	}
+}
+EXPORT_SYMBOL(vringh_kiov_advance);
+
+/* Copy some bytes to/from the iovec.  Returns num copied. */
+static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
+				      struct vringh_kiov *iov,
+				      void *ptr, size_t len,
+				      int (*xfer)(const struct vringh *vrh,
+						  void *addr, void *ptr,
+						  size_t len))
+{
+	int err, done = 0;
+
+	while (len && iov->i < iov->used) {
+		size_t partlen;
+
+		partlen = min(iov->iov[iov->i].iov_len, len);
+		err = xfer(vrh, iov->iov[iov->i].iov_base, ptr, partlen);
+		if (err)
+			return err;
+		done += partlen;
+		len -= partlen;
+		ptr += partlen;
+		iov->consumed += partlen;
+		iov->iov[iov->i].iov_len -= partlen;
+		iov->iov[iov->i].iov_base += partlen;
+
+		if (!iov->iov[iov->i].iov_len) {
+			/* Fix up old iov element then increment. */
+			iov->iov[iov->i].iov_len = iov->consumed;
+			iov->iov[iov->i].iov_base -= iov->consumed;
+
+			iov->consumed = 0;
+			iov->i++;
+		}
+	}
+	return done;
+}
+
+/* May reduce *len if range is shorter. */
+static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
+			       struct vringh_range *range,
+			       bool (*getrange)(struct vringh *,
+						u64, struct vringh_range *))
+{
+	if (addr < range->start || addr > range->end_incl) {
+		if (!getrange(vrh, addr, range))
+			return false;
+	}
+	BUG_ON(addr < range->start || addr > range->end_incl);
+
+	/* To end of memory? */
+	if (unlikely(addr + *len == 0)) {
+		if (range->end_incl == -1ULL)
+			return true;
+		goto truncate;
+	}
+
+	/* Otherwise, don't wrap. */
+	if (addr + *len < addr) {
+		vringh_bad("Wrapping descriptor %zu@0x%llx",
+			   *len, (unsigned long long)addr);
+		return false;
+	}
+
+	if (unlikely(addr + *len - 1 > range->end_incl))
+		goto truncate;
+	return true;
+
+truncate:
+	*len = range->end_incl + 1 - addr;
+	return true;
+}
+
+static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
+				  struct vringh_range *range,
+				  bool (*getrange)(struct vringh *,
+						   u64, struct vringh_range *))
+{
+	return true;
+}
+
+/* No reason for this code to be inline. */
+static int move_to_indirect(const struct vringh *vrh,
+			    int *up_next, u16 *i, void *addr,
+			    const struct vring_desc *desc,
+			    struct vring_desc **descs, int *desc_max)
+{
+	u32 len;
+
+	/* Indirect tables can't have indirect. */
+	if (*up_next != -1) {
+		vringh_bad("Multilevel indirect %u->%u", *up_next, *i);
+		return -EINVAL;
+	}
+
+	len = vringh32_to_cpu(vrh, desc->len);
+	if (unlikely(len % sizeof(struct vring_desc))) {
+		vringh_bad("Strange indirect len %u", desc->len);
+		return -EINVAL;
+	}
+
+	/* We will check this when we follow it! */
+	if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT))
+		*up_next = vringh16_to_cpu(vrh, desc->next);
+	else
+		*up_next = -2;
+	*descs = addr;
+	*desc_max = len / sizeof(struct vring_desc);
+
+	/* Now, start at the first indirect. */
+	*i = 0;
+	return 0;
+}
+
+static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
+{
+	struct kvec *new;
+	unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
+
+	if (new_num < 8)
+		new_num = 8;
+
+	flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
+	if (flag)
+		new = krealloc_array(iov->iov, new_num,
+				     sizeof(struct iovec), gfp);
+	else {
+		new = kmalloc_array(new_num, sizeof(struct iovec), gfp);
+		if (new) {
+			memcpy(new, iov->iov,
+			       iov->max_num * sizeof(struct iovec));
+			flag = VRINGH_IOV_ALLOCATED;
+		}
+	}
+	if (!new)
+		return -ENOMEM;
+	iov->iov = new;
+	iov->max_num = (new_num | flag);
+	return 0;
+}
+
+static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next,
+				       struct vring_desc **descs, int *desc_max)
+{
+	u16 i = *up_next;
+
+	*up_next = -1;
+	*descs = vrh->vring.desc;
+	*desc_max = vrh->vring.num;
+	return i;
+}
+
+static int slow_copy(struct vringh *vrh, void *dst, const void *src,
+		     bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
+				    struct vringh_range *range,
+				    bool (*getrange)(struct vringh *vrh,
+						     u64,
+						     struct vringh_range *)),
+		     bool (*getrange)(struct vringh *vrh,
+				      u64 addr,
+				      struct vringh_range *r),
+		     struct vringh_range *range,
+		     int (*copy)(const struct vringh *vrh,
+				 void *dst, const void *src, size_t len))
+{
+	size_t part, len = sizeof(struct vring_desc);
+
+	do {
+		u64 addr;
+		int err;
+
+		part = len;
+		addr = (u64)(unsigned long)src - range->offset;
+
+		if (!rcheck(vrh, addr, &part, range, getrange))
+			return -EINVAL;
+
+		err = copy(vrh, dst, src, part);
+		if (err)
+			return err;
+
+		dst += part;
+		src += part;
+		len -= part;
+	} while (len);
+	return 0;
+}
+
+static inline int
+__vringh_iov(struct vringh *vrh, u16 i,
+	     struct vringh_kiov *riov,
+	     struct vringh_kiov *wiov,
+	     bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
+			    struct vringh_range *range,
+			    bool (*getrange)(struct vringh *, u64,
+					     struct vringh_range *)),
+	     bool (*getrange)(struct vringh *, u64, struct vringh_range *),
+	     gfp_t gfp,
+	     int (*copy)(const struct vringh *vrh,
+			 void *dst, const void *src, size_t len))
+{
+	int err, count = 0, indirect_count = 0, up_next, desc_max;
+	struct vring_desc desc, *descs;
+	struct vringh_range range = { -1ULL, 0 }, slowrange;
+	bool slow = false;
+
+	/* We start traversing vring's descriptor table. */
+	descs = vrh->vring.desc;
+	desc_max = vrh->vring.num;
+	up_next = -1;
+
+	/* You must want something! */
+	if (WARN_ON(!riov && !wiov))
+		return -EINVAL;
+
+	if (riov)
+		riov->i = riov->used = riov->consumed = 0;
+	if (wiov)
+		wiov->i = wiov->used = wiov->consumed = 0;
+
+	for (;;) {
+		void *addr;
+		struct vringh_kiov *iov;
+		size_t len;
+
+		if (unlikely(slow))
+			err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
+					&slowrange, copy);
+		else
+			err = copy(vrh, &desc, &descs[i], sizeof(desc));
+		if (unlikely(err))
+			goto fail;
+
+		if (unlikely(desc.flags &
+			     cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) {
+			u64 a = vringh64_to_cpu(vrh, desc.addr);
+
+			/* Make sure it's OK, and get offset. */
+			len = vringh32_to_cpu(vrh, desc.len);
+			if (!rcheck(vrh, a, &len, &range, getrange)) {
+				err = -EINVAL;
+				goto fail;
+			}
+
+			if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
+				slow = true;
+				/* We need to save this range to use offset */
+				slowrange = range;
+			}
+
+			addr = (void *)(long)(a + range.offset);
+			err = move_to_indirect(vrh, &up_next, &i, addr, &desc,
+					       &descs, &desc_max);
+			if (err)
+				goto fail;
+			continue;
+		}
+
+		if (up_next == -1)
+			count++;
+		else
+			indirect_count++;
+
+		if (count > vrh->vring.num || indirect_count > desc_max) {
+			vringh_bad("Descriptor loop in %p", descs);
+			err = -ELOOP;
+			goto fail;
+		}
+
+		if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE))
+			iov = wiov;
+		else {
+			iov = riov;
+			if (unlikely(wiov && wiov->used)) {
+				vringh_bad("Readable desc %p after writable",
+					   &descs[i]);
+				err = -EINVAL;
+				goto fail;
+			}
+		}
+
+		if (!iov) {
+			vringh_bad("Unexpected %s desc",
+				   !wiov ? "writable" : "readable");
+			err = -EPROTO;
+			goto fail;
+		}
+
+	again:
+		/* Make sure it's OK, and get offset. */
+		len = vringh32_to_cpu(vrh, desc.len);
+		if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
+			    getrange)) {
+			err = -EINVAL;
+			goto fail;
+		}
+		addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) +
+					       range.offset);
+
+		if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) {
+			err = resize_iovec(iov, gfp);
+			if (err)
+				goto fail;
+		}
+
+		iov->iov[iov->used].iov_base = addr;
+		iov->iov[iov->used].iov_len = len;
+		iov->used++;
+
+		if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
+			desc.len = cpu_to_vringh32(vrh,
+				   vringh32_to_cpu(vrh, desc.len) - len);
+			desc.addr = cpu_to_vringh64(vrh,
+				    vringh64_to_cpu(vrh, desc.addr) + len);
+			goto again;
+		}
+
+		if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) {
+			i = vringh16_to_cpu(vrh, desc.next);
+		} else {
+			/* Just in case we need to finish traversing above. */
+			if (unlikely(up_next > 0)) {
+				i = return_from_indirect(vrh, &up_next,
+							 &descs, &desc_max);
+				slow = false;
+				indirect_count = 0;
+			} else
+				break;
+		}
+
+		if (i >= desc_max) {
+			vringh_bad("Chained index %u > %u", i, desc_max);
+			err = -EINVAL;
+			goto fail;
+		}
+	}
+
+	return 0;
+
+fail:
+	return err;
+}
+
+static inline int __vringh_complete(struct vringh *vrh,
+				    const struct vring_used_elem *used,
+				    unsigned int num_used,
+				    int (*putu16)(const struct vringh *vrh,
+						  __virtio16 *p, u16 val),
+				    int (*putused)(const struct vringh *vrh,
+						   struct vring_used_elem *dst,
+						   const struct vring_used_elem
+						   *src, unsigned num))
+{
+	struct vring_used *used_ring;
+	int err;
+	u16 used_idx, off;
+
+	used_ring = vrh->vring.used;
+	used_idx = vrh->last_used_idx + vrh->completed;
+
+	off = used_idx % vrh->vring.num;
+
+	/* Compiler knows num_used == 1 sometimes, hence extra check */
+	if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) {
+		u16 part = vrh->vring.num - off;
+		err = putused(vrh, &used_ring->ring[off], used, part);
+		if (!err)
+			err = putused(vrh, &used_ring->ring[0], used + part,
+				      num_used - part);
+	} else
+		err = putused(vrh, &used_ring->ring[off], used, num_used);
+
+	if (err) {
+		vringh_bad("Failed to write %u used entries %u at %p",
+			   num_used, off, &used_ring->ring[off]);
+		return err;
+	}
+
+	/* Make sure buffer is written before we update index. */
+	virtio_wmb(vrh->weak_barriers);
+
+	err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
+	if (err) {
+		vringh_bad("Failed to update used index at %p",
+			   &vrh->vring.used->idx);
+		return err;
+	}
+
+	vrh->completed += num_used;
+	return 0;
+}
+
+
+static inline int __vringh_need_notify(struct vringh *vrh,
+				       int (*getu16)(const struct vringh *vrh,
+						     u16 *val,
+						     const __virtio16 *p))
+{
+	bool notify;
+	u16 used_event;
+	int err;
+
+	/* Flush out used index update. This is paired with the
+	 * barrier that the Guest executes when enabling
+	 * interrupts. */
+	virtio_mb(vrh->weak_barriers);
+
+	/* Old-style, without event indices. */
+	if (!vrh->event_indices) {
+		u16 flags;
+		err = getu16(vrh, &flags, &vrh->vring.avail->flags);
+		if (err) {
+			vringh_bad("Failed to get flags at %p",
+				   &vrh->vring.avail->flags);
+			return err;
+		}
+		return (!(flags & VRING_AVAIL_F_NO_INTERRUPT));
+	}
+
+	/* Modern: we know when other side wants to know. */
+	err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
+	if (err) {
+		vringh_bad("Failed to get used event idx at %p",
+			   &vring_used_event(&vrh->vring));
+		return err;
+	}
+
+	/* Just in case we added so many that we wrap. */
+	if (unlikely(vrh->completed > 0xffff))
+		notify = true;
+	else
+		notify = vring_need_event(used_event,
+					  vrh->last_used_idx + vrh->completed,
+					  vrh->last_used_idx);
+
+	vrh->last_used_idx += vrh->completed;
+	vrh->completed = 0;
+	return notify;
+}
+
+static inline bool __vringh_notify_enable(struct vringh *vrh,
+					  int (*getu16)(const struct vringh *vrh,
+							u16 *val, const __virtio16 *p),
+					  int (*putu16)(const struct vringh *vrh,
+							__virtio16 *p, u16 val))
+{
+	u16 avail;
+
+	if (!vrh->event_indices) {
+		/* Old-school; update flags. */
+		if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
+			vringh_bad("Clearing used flags %p",
+				   &vrh->vring.used->flags);
+			return true;
+		}
+	} else {
+		if (putu16(vrh, &vring_avail_event(&vrh->vring),
+			   vrh->last_avail_idx) != 0) {
+			vringh_bad("Updating avail event index %p",
+				   &vring_avail_event(&vrh->vring));
+			return true;
+		}
+	}
+
+	/* They could have slipped one in as we were doing that: make
+	 * sure it's written, then check again. */
+	virtio_mb(vrh->weak_barriers);
+
+	if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
+		vringh_bad("Failed to check avail idx at %p",
+			   &vrh->vring.avail->idx);
+		return true;
+	}
+
+	/* This is unlikely, so we just leave notifications enabled
+	 * (if we're using event_indices, we'll only get one
+	 * notification anyway). */
+	return avail == vrh->last_avail_idx;
+}
+
+static inline void __vringh_notify_disable(struct vringh *vrh,
+					   int (*putu16)(const struct vringh *vrh,
+							 __virtio16 *p, u16 val))
+{
+	if (!vrh->event_indices) {
+		/* Old-school; update flags. */
+		if (putu16(vrh, &vrh->vring.used->flags,
+			   VRING_USED_F_NO_NOTIFY)) {
+			vringh_bad("Setting used flags %p",
+				   &vrh->vring.used->flags);
+		}
+	}
+}
+
+/* Userspace access helpers: in this case, addresses are really userspace. */
+static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p)
+{
+	__virtio16 v = 0;
+	int rc = get_user(v, (__force __virtio16 __user *)p);
+	*val = vringh16_to_cpu(vrh, v);
+	return rc;
+}
+
+static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val)
+{
+	__virtio16 v = cpu_to_vringh16(vrh, val);
+	return put_user(v, (__force __virtio16 __user *)p);
+}
+
+static inline int copydesc_user(const struct vringh *vrh,
+				void *dst, const void *src, size_t len)
+{
+	return copy_from_user(dst, (__force void __user *)src, len) ?
+		-EFAULT : 0;
+}
+
+static inline int putused_user(const struct vringh *vrh,
+			       struct vring_used_elem *dst,
+			       const struct vring_used_elem *src,
+			       unsigned int num)
+{
+	return copy_to_user((__force void __user *)dst, src,
+			    sizeof(*dst) * num) ? -EFAULT : 0;
+}
+
+static inline int xfer_from_user(const struct vringh *vrh, void *src,
+				 void *dst, size_t len)
+{
+	return copy_from_user(dst, (__force void __user *)src, len) ?
+		-EFAULT : 0;
+}
+
+static inline int xfer_to_user(const struct vringh *vrh,
+			       void *dst, void *src, size_t len)
+{
+	return copy_to_user((__force void __user *)dst, src, len) ?
+		-EFAULT : 0;
+}
+
+/**
+ * vringh_init_user - initialize a vringh for a userspace vring.
+ * @vrh: the vringh to initialize.
+ * @features: the feature bits for this ring.
+ * @num: the number of elements.
+ * @weak_barriers: true if we only need memory barriers, not I/O.
+ * @desc: the userspace descriptor pointer.
+ * @avail: the userspace avail pointer.
+ * @used: the userspace used pointer.
+ *
+ * Returns an error if num is invalid: you should check pointers
+ * yourself!
+ */
+int vringh_init_user(struct vringh *vrh, u64 features,
+		     unsigned int num, bool weak_barriers,
+		     vring_desc_t __user *desc,
+		     vring_avail_t __user *avail,
+		     vring_used_t __user *used)
+{
+	/* Sane power of 2 please! */
+	if (!num || num > 0xffff || (num & (num - 1))) {
+		vringh_bad("Bad ring size %u", num);
+		return -EINVAL;
+	}
+
+	vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
+	vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
+	vrh->weak_barriers = weak_barriers;
+	vrh->completed = 0;
+	vrh->last_avail_idx = 0;
+	vrh->last_used_idx = 0;
+	vrh->vring.num = num;
+	/* vring expects kernel addresses, but only used via accessors. */
+	vrh->vring.desc = (__force struct vring_desc *)desc;
+	vrh->vring.avail = (__force struct vring_avail *)avail;
+	vrh->vring.used = (__force struct vring_used *)used;
+	return 0;
+}
+EXPORT_SYMBOL(vringh_init_user);
+
+/**
+ * vringh_getdesc_user - get next available descriptor from userspace ring.
+ * @vrh: the userspace vring.
+ * @riov: where to put the readable descriptors (or NULL)
+ * @wiov: where to put the writable descriptors (or NULL)
+ * @getrange: function to call to check ranges.
+ * @head: head index we received, for passing to vringh_complete_user().
+ *
+ * Returns 0 if there was no descriptor, 1 if there was, or -errno.
+ *
+ * Note that on error return, you can tell the difference between an
+ * invalid ring and a single invalid descriptor: in the former case,
+ * *head will be vrh->vring.num.  You may be able to ignore an invalid
+ * descriptor, but there's not much you can do with an invalid ring.
+ *
+ * Note that you can reuse riov and wiov with subsequent calls. Content is
+ * overwritten and memory reallocated if more space is needed.
+ * When you don't have to use riov and wiov anymore, you should clean up them
+ * calling vringh_iov_cleanup() to release the memory, even on error!
+ */
+int vringh_getdesc_user(struct vringh *vrh,
+			struct vringh_iov *riov,
+			struct vringh_iov *wiov,
+			bool (*getrange)(struct vringh *vrh,
+					 u64 addr, struct vringh_range *r),
+			u16 *head)
+{
+	int err;
+
+	*head = vrh->vring.num;
+	err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
+	if (err < 0)
+		return err;
+
+	/* Empty... */
+	if (err == vrh->vring.num)
+		return 0;
+
+	/* We need the layouts to be the identical for this to work */
+	BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
+	BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
+		     offsetof(struct vringh_iov, iov));
+	BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
+		     offsetof(struct vringh_iov, i));
+	BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
+		     offsetof(struct vringh_iov, used));
+	BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
+		     offsetof(struct vringh_iov, max_num));
+	BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
+	BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
+		     offsetof(struct kvec, iov_base));
+	BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
+		     offsetof(struct kvec, iov_len));
+	BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
+		     != sizeof(((struct kvec *)NULL)->iov_base));
+	BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
+		     != sizeof(((struct kvec *)NULL)->iov_len));
+
+	*head = err;
+	err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
+			   (struct vringh_kiov *)wiov,
+			   range_check, getrange, GFP_KERNEL, copydesc_user);
+	if (err)
+		return err;
+
+	return 1;
+}
+EXPORT_SYMBOL(vringh_getdesc_user);
+
+/**
+ * vringh_iov_pull_user - copy bytes from vring_iov.
+ * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
+ * @dst: the place to copy.
+ * @len: the maximum length to copy.
+ *
+ * Returns the bytes copied <= len or a negative errno.
+ */
+ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
+{
+	return vringh_iov_xfer(NULL, (struct vringh_kiov *)riov,
+			       dst, len, xfer_from_user);
+}
+EXPORT_SYMBOL(vringh_iov_pull_user);
+
+/**
+ * vringh_iov_push_user - copy bytes into vring_iov.
+ * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
+ * @src: the place to copy from.
+ * @len: the maximum length to copy.
+ *
+ * Returns the bytes copied <= len or a negative errno.
+ */
+ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
+			     const void *src, size_t len)
+{
+	return vringh_iov_xfer(NULL, (struct vringh_kiov *)wiov,
+			       (void *)src, len, xfer_to_user);
+}
+EXPORT_SYMBOL(vringh_iov_push_user);
+
+/**
+ * vringh_abandon_user - we've decided not to handle the descriptor(s).
+ * @vrh: the vring.
+ * @num: the number of descriptors to put back (ie. num
+ *	 vringh_get_user() to undo).
+ *
+ * The next vringh_get_user() will return the old descriptor(s) again.
+ */
+void vringh_abandon_user(struct vringh *vrh, unsigned int num)
+{
+	/* We only update vring_avail_event(vr) when we want to be notified,
+	 * so we haven't changed that yet. */
+	vrh->last_avail_idx -= num;
+}
+EXPORT_SYMBOL(vringh_abandon_user);
+
+/**
+ * vringh_complete_user - we've finished with descriptor, publish it.
+ * @vrh: the vring.
+ * @head: the head as filled in by vringh_getdesc_user.
+ * @len: the length of data we have written.
+ *
+ * You should check vringh_need_notify_user() after one or more calls
+ * to this function.
+ */
+int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
+{
+	struct vring_used_elem used;
+
+	used.id = cpu_to_vringh32(vrh, head);
+	used.len = cpu_to_vringh32(vrh, len);
+	return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
+}
+EXPORT_SYMBOL(vringh_complete_user);
+
+/**
+ * vringh_complete_multi_user - we've finished with many descriptors.
+ * @vrh: the vring.
+ * @used: the head, length pairs.
+ * @num_used: the number of used elements.
+ *
+ * You should check vringh_need_notify_user() after one or more calls
+ * to this function.
+ */
+int vringh_complete_multi_user(struct vringh *vrh,
+			       const struct vring_used_elem used[],
+			       unsigned num_used)
+{
+	return __vringh_complete(vrh, used, num_used,
+				 putu16_user, putused_user);
+}
+EXPORT_SYMBOL(vringh_complete_multi_user);
+
+/**
+ * vringh_notify_enable_user - we want to know if something changes.
+ * @vrh: the vring.
+ *
+ * This always enables notifications, but returns false if there are
+ * now more buffers available in the vring.
+ */
+bool vringh_notify_enable_user(struct vringh *vrh)
+{
+	return __vringh_notify_enable(vrh, getu16_user, putu16_user);
+}
+EXPORT_SYMBOL(vringh_notify_enable_user);
+
+/**
+ * vringh_notify_disable_user - don't tell us if something changes.
+ * @vrh: the vring.
+ *
+ * This is our normal running state: we disable and then only enable when
+ * we're going to sleep.
+ */
+void vringh_notify_disable_user(struct vringh *vrh)
+{
+	__vringh_notify_disable(vrh, putu16_user);
+}
+EXPORT_SYMBOL(vringh_notify_disable_user);
+
+/**
+ * vringh_need_notify_user - must we tell the other side about used buffers?
+ * @vrh: the vring we've called vringh_complete_user() on.
+ *
+ * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
+ */
+int vringh_need_notify_user(struct vringh *vrh)
+{
+	return __vringh_need_notify(vrh, getu16_user);
+}
+EXPORT_SYMBOL(vringh_need_notify_user);
+
+/* Kernelspace access helpers. */
+static inline int getu16_kern(const struct vringh *vrh,
+			      u16 *val, const __virtio16 *p)
+{
+	*val = vringh16_to_cpu(vrh, READ_ONCE(*p));
+	return 0;
+}
+
+static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val)
+{
+	WRITE_ONCE(*p, cpu_to_vringh16(vrh, val));
+	return 0;
+}
+
+static inline int copydesc_kern(const struct vringh *vrh,
+				void *dst, const void *src, size_t len)
+{
+	memcpy(dst, src, len);
+	return 0;
+}
+
+static inline int putused_kern(const struct vringh *vrh,
+			       struct vring_used_elem *dst,
+			       const struct vring_used_elem *src,
+			       unsigned int num)
+{
+	memcpy(dst, src, num * sizeof(*dst));
+	return 0;
+}
+
+static inline int xfer_kern(const struct vringh *vrh, void *src,
+			    void *dst, size_t len)
+{
+	memcpy(dst, src, len);
+	return 0;
+}
+
+static inline int kern_xfer(const struct vringh *vrh, void *dst,
+			    void *src, size_t len)
+{
+	memcpy(dst, src, len);
+	return 0;
+}
+
+/**
+ * vringh_init_kern - initialize a vringh for a kernelspace vring.
+ * @vrh: the vringh to initialize.
+ * @features: the feature bits for this ring.
+ * @num: the number of elements.
+ * @weak_barriers: true if we only need memory barriers, not I/O.
+ * @desc: the userspace descriptor pointer.
+ * @avail: the userspace avail pointer.
+ * @used: the userspace used pointer.
+ *
+ * Returns an error if num is invalid.
+ */
+int vringh_init_kern(struct vringh *vrh, u64 features,
+		     unsigned int num, bool weak_barriers,
+		     struct vring_desc *desc,
+		     struct vring_avail *avail,
+		     struct vring_used *used)
+{
+	/* Sane power of 2 please! */
+	if (!num || num > 0xffff || (num & (num - 1))) {
+		vringh_bad("Bad ring size %u", num);
+		return -EINVAL;
+	}
+
+	vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
+	vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
+	vrh->weak_barriers = weak_barriers;
+	vrh->completed = 0;
+	vrh->last_avail_idx = 0;
+	vrh->last_used_idx = 0;
+	vrh->vring.num = num;
+	vrh->vring.desc = desc;
+	vrh->vring.avail = avail;
+	vrh->vring.used = used;
+	return 0;
+}
+EXPORT_SYMBOL(vringh_init_kern);
+
+/**
+ * vringh_getdesc_kern - get next available descriptor from kernelspace ring.
+ * @vrh: the kernelspace vring.
+ * @riov: where to put the readable descriptors (or NULL)
+ * @wiov: where to put the writable descriptors (or NULL)
+ * @head: head index we received, for passing to vringh_complete_kern().
+ * @gfp: flags for allocating larger riov/wiov.
+ *
+ * Returns 0 if there was no descriptor, 1 if there was, or -errno.
+ *
+ * Note that on error return, you can tell the difference between an
+ * invalid ring and a single invalid descriptor: in the former case,
+ * *head will be vrh->vring.num.  You may be able to ignore an invalid
+ * descriptor, but there's not much you can do with an invalid ring.
+ *
+ * Note that you can reuse riov and wiov with subsequent calls. Content is
+ * overwritten and memory reallocated if more space is needed.
+ * When you don't have to use riov and wiov anymore, you should clean up them
+ * calling vringh_kiov_cleanup() to release the memory, even on error!
+ */
+int vringh_getdesc_kern(struct vringh *vrh,
+			struct vringh_kiov *riov,
+			struct vringh_kiov *wiov,
+			u16 *head,
+			gfp_t gfp)
+{
+	int err;
+
+	err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
+	if (err < 0)
+		return err;
+
+	/* Empty... */
+	if (err == vrh->vring.num)
+		return 0;
+
+	*head = err;
+	err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
+			   gfp, copydesc_kern);
+	if (err)
+		return err;
+
+	return 1;
+}
+EXPORT_SYMBOL(vringh_getdesc_kern);
+
+/**
+ * vringh_iov_pull_kern - copy bytes from vring_iov.
+ * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
+ * @dst: the place to copy.
+ * @len: the maximum length to copy.
+ *
+ * Returns the bytes copied <= len or a negative errno.
+ */
+ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
+{
+	return vringh_iov_xfer(NULL, riov, dst, len, xfer_kern);
+}
+EXPORT_SYMBOL(vringh_iov_pull_kern);
+
+/**
+ * vringh_iov_push_kern - copy bytes into vring_iov.
+ * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
+ * @src: the place to copy from.
+ * @len: the maximum length to copy.
+ *
+ * Returns the bytes copied <= len or a negative errno.
+ */
+ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
+			     const void *src, size_t len)
+{
+	return vringh_iov_xfer(NULL, wiov, (void *)src, len, kern_xfer);
+}
+EXPORT_SYMBOL(vringh_iov_push_kern);
+
+/**
+ * vringh_abandon_kern - we've decided not to handle the descriptor(s).
+ * @vrh: the vring.
+ * @num: the number of descriptors to put back (ie. num
+ *	 vringh_get_kern() to undo).
+ *
+ * The next vringh_get_kern() will return the old descriptor(s) again.
+ */
+void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
+{
+	/* We only update vring_avail_event(vr) when we want to be notified,
+	 * so we haven't changed that yet. */
+	vrh->last_avail_idx -= num;
+}
+EXPORT_SYMBOL(vringh_abandon_kern);
+
+/**
+ * vringh_complete_kern - we've finished with descriptor, publish it.
+ * @vrh: the vring.
+ * @head: the head as filled in by vringh_getdesc_kern.
+ * @len: the length of data we have written.
+ *
+ * You should check vringh_need_notify_kern() after one or more calls
+ * to this function.
+ */
+int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
+{
+	struct vring_used_elem used;
+
+	used.id = cpu_to_vringh32(vrh, head);
+	used.len = cpu_to_vringh32(vrh, len);
+
+	return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
+}
+EXPORT_SYMBOL(vringh_complete_kern);
+
+/**
+ * vringh_notify_enable_kern - we want to know if something changes.
+ * @vrh: the vring.
+ *
+ * This always enables notifications, but returns false if there are
+ * now more buffers available in the vring.
+ */
+bool vringh_notify_enable_kern(struct vringh *vrh)
+{
+	return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
+}
+EXPORT_SYMBOL(vringh_notify_enable_kern);
+
+/**
+ * vringh_notify_disable_kern - don't tell us if something changes.
+ * @vrh: the vring.
+ *
+ * This is our normal running state: we disable and then only enable when
+ * we're going to sleep.
+ */
+void vringh_notify_disable_kern(struct vringh *vrh)
+{
+	__vringh_notify_disable(vrh, putu16_kern);
+}
+EXPORT_SYMBOL(vringh_notify_disable_kern);
+
+/**
+ * vringh_need_notify_kern - must we tell the other side about used buffers?
+ * @vrh: the vring we've called vringh_complete_kern() on.
+ *
+ * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
+ */
+int vringh_need_notify_kern(struct vringh *vrh)
+{
+	return __vringh_need_notify(vrh, getu16_kern);
+}
+EXPORT_SYMBOL(vringh_need_notify_kern);
+
+#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
+
+struct iotlb_vec {
+	union {
+		struct iovec *iovec;
+		struct bio_vec *bvec;
+	} iov;
+	size_t count;
+};
+
+static int iotlb_translate(const struct vringh *vrh,
+			   u64 addr, u64 len, u64 *translated,
+			   struct iotlb_vec *ivec, u32 perm)
+{
+	struct vhost_iotlb_map *map;
+	struct vhost_iotlb *iotlb = vrh->iotlb;
+	int ret = 0;
+	u64 s = 0, last = addr + len - 1;
+
+	spin_lock(vrh->iotlb_lock);
+
+	while (len > s) {
+		uintptr_t io_addr;
+		size_t io_len;
+		u64 size;
+
+		if (unlikely(ret >= ivec->count)) {
+			ret = -ENOBUFS;
+			break;
+		}
+
+		map = vhost_iotlb_itree_first(iotlb, addr, last);
+		if (!map || map->start > addr) {
+			ret = -EINVAL;
+			break;
+		} else if (!(map->perm & perm)) {
+			ret = -EPERM;
+			break;
+		}
+
+		size = map->size - addr + map->start;
+		io_len = min(len - s, size);
+		io_addr = map->addr - map->start + addr;
+
+		if (vrh->use_va) {
+			struct iovec *iovec = ivec->iov.iovec;
+
+			iovec[ret].iov_len = io_len;
+			iovec[ret].iov_base = (void __user *)io_addr;
+		} else {
+			u64 pfn = io_addr >> PAGE_SHIFT;
+			struct bio_vec *bvec = ivec->iov.bvec;
+
+			bvec_set_page(&bvec[ret], pfn_to_page(pfn), io_len,
+				      io_addr & (PAGE_SIZE - 1));
+		}
+
+		s += size;
+		addr += size;
+		++ret;
+	}
+
+	spin_unlock(vrh->iotlb_lock);
+
+	if (translated)
+		*translated = min(len, s);
+
+	return ret;
+}
+
+#define IOTLB_IOV_STRIDE 16
+
+static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
+				  void *src, size_t len)
+{
+	struct iotlb_vec ivec;
+	union {
+		struct iovec iovec[IOTLB_IOV_STRIDE];
+		struct bio_vec bvec[IOTLB_IOV_STRIDE];
+	} iov;
+	u64 total_translated = 0;
+
+	ivec.iov.iovec = iov.iovec;
+	ivec.count = IOTLB_IOV_STRIDE;
+
+	while (total_translated < len) {
+		struct iov_iter iter;
+		u64 translated;
+		int ret;
+
+		ret = iotlb_translate(vrh, (u64)(uintptr_t)src,
+				      len - total_translated, &translated,
+				      &ivec, VHOST_MAP_RO);
+		if (ret == -ENOBUFS)
+			ret = IOTLB_IOV_STRIDE;
+		else if (ret < 0)
+			return ret;
+
+		if (vrh->use_va) {
+			iov_iter_init(&iter, ITER_SOURCE, ivec.iov.iovec, ret,
+				      translated);
+		} else {
+			iov_iter_bvec(&iter, ITER_SOURCE, ivec.iov.bvec, ret,
+				      translated);
+		}
+
+		ret = copy_from_iter(dst, translated, &iter);
+		if (ret < 0)
+			return ret;
+
+		src += translated;
+		dst += translated;
+		total_translated += translated;
+	}
+
+	return total_translated;
+}
+
+static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
+				void *src, size_t len)
+{
+	struct iotlb_vec ivec;
+	union {
+		struct iovec iovec[IOTLB_IOV_STRIDE];
+		struct bio_vec bvec[IOTLB_IOV_STRIDE];
+	} iov;
+	u64 total_translated = 0;
+
+	ivec.iov.iovec = iov.iovec;
+	ivec.count = IOTLB_IOV_STRIDE;
+
+	while (total_translated < len) {
+		struct iov_iter iter;
+		u64 translated;
+		int ret;
+
+		ret = iotlb_translate(vrh, (u64)(uintptr_t)dst,
+				      len - total_translated, &translated,
+				      &ivec, VHOST_MAP_WO);
+		if (ret == -ENOBUFS)
+			ret = IOTLB_IOV_STRIDE;
+		else if (ret < 0)
+			return ret;
+
+		if (vrh->use_va) {
+			iov_iter_init(&iter, ITER_DEST, ivec.iov.iovec, ret,
+				      translated);
+		} else {
+			iov_iter_bvec(&iter, ITER_DEST, ivec.iov.bvec, ret,
+				      translated);
+		}
+
+		ret = copy_to_iter(src, translated, &iter);
+		if (ret < 0)
+			return ret;
+
+		src += translated;
+		dst += translated;
+		total_translated += translated;
+	}
+
+	return total_translated;
+}
+
+static inline int getu16_iotlb(const struct vringh *vrh,
+			       u16 *val, const __virtio16 *p)
+{
+	struct iotlb_vec ivec;
+	union {
+		struct iovec iovec[1];
+		struct bio_vec bvec[1];
+	} iov;
+	__virtio16 tmp;
+	int ret;
+
+	ivec.iov.iovec = iov.iovec;
+	ivec.count = 1;
+
+	/* Atomic read is needed for getu16 */
+	ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
+			      NULL, &ivec, VHOST_MAP_RO);
+	if (ret < 0)
+		return ret;
+
+	if (vrh->use_va) {
+		ret = __get_user(tmp, (__virtio16 __user *)ivec.iov.iovec[0].iov_base);
+		if (ret)
+			return ret;
+	} else {
+		void *kaddr = kmap_local_page(ivec.iov.bvec[0].bv_page);
+		void *from = kaddr + ivec.iov.bvec[0].bv_offset;
+
+		tmp = READ_ONCE(*(__virtio16 *)from);
+		kunmap_local(kaddr);
+	}
+
+	*val = vringh16_to_cpu(vrh, tmp);
+
+	return 0;
+}
+
+static inline int putu16_iotlb(const struct vringh *vrh,
+			       __virtio16 *p, u16 val)
+{
+	struct iotlb_vec ivec;
+	union {
+		struct iovec iovec;
+		struct bio_vec bvec;
+	} iov;
+	__virtio16 tmp;
+	int ret;
+
+	ivec.iov.iovec = &iov.iovec;
+	ivec.count = 1;
+
+	/* Atomic write is needed for putu16 */
+	ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
+			      NULL, &ivec, VHOST_MAP_RO);
+	if (ret < 0)
+		return ret;
+
+	tmp = cpu_to_vringh16(vrh, val);
+
+	if (vrh->use_va) {
+		ret = __put_user(tmp, (__virtio16 __user *)ivec.iov.iovec[0].iov_base);
+		if (ret)
+			return ret;
+	} else {
+		void *kaddr = kmap_local_page(ivec.iov.bvec[0].bv_page);
+		void *to = kaddr + ivec.iov.bvec[0].bv_offset;
+
+		WRITE_ONCE(*(__virtio16 *)to, tmp);
+		kunmap_local(kaddr);
+	}
+
+	return 0;
+}
+
+static inline int copydesc_iotlb(const struct vringh *vrh,
+				 void *dst, const void *src, size_t len)
+{
+	int ret;
+
+	ret = copy_from_iotlb(vrh, dst, (void *)src, len);
+	if (ret != len)
+		return -EFAULT;
+
+	return 0;
+}
+
+static inline int xfer_from_iotlb(const struct vringh *vrh, void *src,
+				  void *dst, size_t len)
+{
+	int ret;
+
+	ret = copy_from_iotlb(vrh, dst, src, len);
+	if (ret != len)
+		return -EFAULT;
+
+	return 0;
+}
+
+static inline int xfer_to_iotlb(const struct vringh *vrh,
+			       void *dst, void *src, size_t len)
+{
+	int ret;
+
+	ret = copy_to_iotlb(vrh, dst, src, len);
+	if (ret != len)
+		return -EFAULT;
+
+	return 0;
+}
+
+static inline int putused_iotlb(const struct vringh *vrh,
+				struct vring_used_elem *dst,
+				const struct vring_used_elem *src,
+				unsigned int num)
+{
+	int size = num * sizeof(*dst);
+	int ret;
+
+	ret = copy_to_iotlb(vrh, dst, (void *)src, num * sizeof(*dst));
+	if (ret != size)
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * vringh_init_iotlb - initialize a vringh for a ring with IOTLB.
+ * @vrh: the vringh to initialize.
+ * @features: the feature bits for this ring.
+ * @num: the number of elements.
+ * @weak_barriers: true if we only need memory barriers, not I/O.
+ * @desc: the userspace descriptor pointer.
+ * @avail: the userspace avail pointer.
+ * @used: the userspace used pointer.
+ *
+ * Returns an error if num is invalid.
+ */
+int vringh_init_iotlb(struct vringh *vrh, u64 features,
+		      unsigned int num, bool weak_barriers,
+		      struct vring_desc *desc,
+		      struct vring_avail *avail,
+		      struct vring_used *used)
+{
+	vrh->use_va = false;
+
+	return vringh_init_kern(vrh, features, num, weak_barriers,
+				desc, avail, used);
+}
+EXPORT_SYMBOL(vringh_init_iotlb);
+
+/**
+ * vringh_init_iotlb_va - initialize a vringh for a ring with IOTLB containing
+ *                        user VA.
+ * @vrh: the vringh to initialize.
+ * @features: the feature bits for this ring.
+ * @num: the number of elements.
+ * @weak_barriers: true if we only need memory barriers, not I/O.
+ * @desc: the userspace descriptor pointer.
+ * @avail: the userspace avail pointer.
+ * @used: the userspace used pointer.
+ *
+ * Returns an error if num is invalid.
+ */
+int vringh_init_iotlb_va(struct vringh *vrh, u64 features,
+			 unsigned int num, bool weak_barriers,
+			 struct vring_desc *desc,
+			 struct vring_avail *avail,
+			 struct vring_used *used)
+{
+	vrh->use_va = true;
+
+	return vringh_init_kern(vrh, features, num, weak_barriers,
+				desc, avail, used);
+}
+EXPORT_SYMBOL(vringh_init_iotlb_va);
+
+/**
+ * vringh_set_iotlb - initialize a vringh for a ring with IOTLB.
+ * @vrh: the vring
+ * @iotlb: iotlb associated with this vring
+ * @iotlb_lock: spinlock to synchronize the iotlb accesses
+ */
+void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
+		      spinlock_t *iotlb_lock)
+{
+	vrh->iotlb = iotlb;
+	vrh->iotlb_lock = iotlb_lock;
+}
+EXPORT_SYMBOL(vringh_set_iotlb);
+
+/**
+ * vringh_getdesc_iotlb - get next available descriptor from ring with
+ * IOTLB.
+ * @vrh: the kernelspace vring.
+ * @riov: where to put the readable descriptors (or NULL)
+ * @wiov: where to put the writable descriptors (or NULL)
+ * @head: head index we received, for passing to vringh_complete_iotlb().
+ * @gfp: flags for allocating larger riov/wiov.
+ *
+ * Returns 0 if there was no descriptor, 1 if there was, or -errno.
+ *
+ * Note that on error return, you can tell the difference between an
+ * invalid ring and a single invalid descriptor: in the former case,
+ * *head will be vrh->vring.num.  You may be able to ignore an invalid
+ * descriptor, but there's not much you can do with an invalid ring.
+ *
+ * Note that you can reuse riov and wiov with subsequent calls. Content is
+ * overwritten and memory reallocated if more space is needed.
+ * When you don't have to use riov and wiov anymore, you should clean up them
+ * calling vringh_kiov_cleanup() to release the memory, even on error!
+ */
+int vringh_getdesc_iotlb(struct vringh *vrh,
+			 struct vringh_kiov *riov,
+			 struct vringh_kiov *wiov,
+			 u16 *head,
+			 gfp_t gfp)
+{
+	int err;
+
+	err = __vringh_get_head(vrh, getu16_iotlb, &vrh->last_avail_idx);
+	if (err < 0)
+		return err;
+
+	/* Empty... */
+	if (err == vrh->vring.num)
+		return 0;
+
+	*head = err;
+	err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
+			   gfp, copydesc_iotlb);
+	if (err)
+		return err;
+
+	return 1;
+}
+EXPORT_SYMBOL(vringh_getdesc_iotlb);
+
+/**
+ * vringh_iov_pull_iotlb - copy bytes from vring_iov.
+ * @vrh: the vring.
+ * @riov: the riov as passed to vringh_getdesc_iotlb() (updated as we consume)
+ * @dst: the place to copy.
+ * @len: the maximum length to copy.
+ *
+ * Returns the bytes copied <= len or a negative errno.
+ */
+ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
+			      struct vringh_kiov *riov,
+			      void *dst, size_t len)
+{
+	return vringh_iov_xfer(vrh, riov, dst, len, xfer_from_iotlb);
+}
+EXPORT_SYMBOL(vringh_iov_pull_iotlb);
+
+/**
+ * vringh_iov_push_iotlb - copy bytes into vring_iov.
+ * @vrh: the vring.
+ * @wiov: the wiov as passed to vringh_getdesc_iotlb() (updated as we consume)
+ * @src: the place to copy from.
+ * @len: the maximum length to copy.
+ *
+ * Returns the bytes copied <= len or a negative errno.
+ */
+ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
+			      struct vringh_kiov *wiov,
+			      const void *src, size_t len)
+{
+	return vringh_iov_xfer(vrh, wiov, (void *)src, len, xfer_to_iotlb);
+}
+EXPORT_SYMBOL(vringh_iov_push_iotlb);
+
+/**
+ * vringh_abandon_iotlb - we've decided not to handle the descriptor(s).
+ * @vrh: the vring.
+ * @num: the number of descriptors to put back (ie. num
+ *	 vringh_get_iotlb() to undo).
+ *
+ * The next vringh_get_iotlb() will return the old descriptor(s) again.
+ */
+void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num)
+{
+	/* We only update vring_avail_event(vr) when we want to be notified,
+	 * so we haven't changed that yet.
+	 */
+	vrh->last_avail_idx -= num;
+}
+EXPORT_SYMBOL(vringh_abandon_iotlb);
+
+/**
+ * vringh_complete_iotlb - we've finished with descriptor, publish it.
+ * @vrh: the vring.
+ * @head: the head as filled in by vringh_getdesc_iotlb.
+ * @len: the length of data we have written.
+ *
+ * You should check vringh_need_notify_iotlb() after one or more calls
+ * to this function.
+ */
+int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len)
+{
+	struct vring_used_elem used;
+
+	used.id = cpu_to_vringh32(vrh, head);
+	used.len = cpu_to_vringh32(vrh, len);
+
+	return __vringh_complete(vrh, &used, 1, putu16_iotlb, putused_iotlb);
+}
+EXPORT_SYMBOL(vringh_complete_iotlb);
+
+/**
+ * vringh_notify_enable_iotlb - we want to know if something changes.
+ * @vrh: the vring.
+ *
+ * This always enables notifications, but returns false if there are
+ * now more buffers available in the vring.
+ */
+bool vringh_notify_enable_iotlb(struct vringh *vrh)
+{
+	return __vringh_notify_enable(vrh, getu16_iotlb, putu16_iotlb);
+}
+EXPORT_SYMBOL(vringh_notify_enable_iotlb);
+
+/**
+ * vringh_notify_disable_iotlb - don't tell us if something changes.
+ * @vrh: the vring.
+ *
+ * This is our normal running state: we disable and then only enable when
+ * we're going to sleep.
+ */
+void vringh_notify_disable_iotlb(struct vringh *vrh)
+{
+	__vringh_notify_disable(vrh, putu16_iotlb);
+}
+EXPORT_SYMBOL(vringh_notify_disable_iotlb);
+
+/**
+ * vringh_need_notify_iotlb - must we tell the other side about used buffers?
+ * @vrh: the vring we've called vringh_complete_iotlb() on.
+ *
+ * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
+ */
+int vringh_need_notify_iotlb(struct vringh *vrh)
+{
+	return __vringh_need_notify(vrh, getu16_iotlb);
+}
+EXPORT_SYMBOL(vringh_need_notify_iotlb);
+
+#endif
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
new file mode 100644
index 000000000..61255855d
--- /dev/null
+++ b/drivers/vhost/vsock.c
@@ -0,0 +1,950 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vhost transport for vsock
+ *
+ * Copyright (C) 2013-2015 Red Hat, Inc.
+ * Author: Asias He <asias@redhat.com>
+ *         Stefan Hajnoczi <stefanha@redhat.com>
+ */
+#include <linux/miscdevice.h>
+#include <linux/atomic.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/vmalloc.h>
+#include <net/sock.h>
+#include <linux/virtio_vsock.h>
+#include <linux/vhost.h>
+#include <linux/hashtable.h>
+
+#include <net/af_vsock.h>
+#include "vhost.h"
+
+#define VHOST_VSOCK_DEFAULT_HOST_CID	2
+/* Max number of bytes transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others. */
+#define VHOST_VSOCK_WEIGHT 0x80000
+/* Max number of packets transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others with
+ * small pkts.
+ */
+#define VHOST_VSOCK_PKT_WEIGHT 256
+
+enum {
+	VHOST_VSOCK_FEATURES = VHOST_FEATURES |
+			       (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
+			       (1ULL << VIRTIO_VSOCK_F_SEQPACKET)
+};
+
+enum {
+	VHOST_VSOCK_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
+};
+
+/* Used to track all the vhost_vsock instances on the system. */
+static DEFINE_MUTEX(vhost_vsock_mutex);
+static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
+
+struct vhost_vsock {
+	struct vhost_dev dev;
+	struct vhost_virtqueue vqs[2];
+
+	/* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
+	struct hlist_node hash;
+
+	struct vhost_work send_pkt_work;
+	struct sk_buff_head send_pkt_queue; /* host->guest pending packets */
+
+	atomic_t queued_replies;
+
+	u32 guest_cid;
+	bool seqpacket_allow;
+};
+
+static u32 vhost_transport_get_local_cid(void)
+{
+	return VHOST_VSOCK_DEFAULT_HOST_CID;
+}
+
+/* Callers that dereference the return value must hold vhost_vsock_mutex or the
+ * RCU read lock.
+ */
+static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
+{
+	struct vhost_vsock *vsock;
+
+	hash_for_each_possible_rcu(vhost_vsock_hash, vsock, hash, guest_cid) {
+		u32 other_cid = vsock->guest_cid;
+
+		/* Skip instances that have no CID yet */
+		if (other_cid == 0)
+			continue;
+
+		if (other_cid == guest_cid)
+			return vsock;
+
+	}
+
+	return NULL;
+}
+
+static void
+vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
+			    struct vhost_virtqueue *vq)
+{
+	struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
+	int pkts = 0, total_len = 0;
+	bool added = false;
+	bool restart_tx = false;
+
+	mutex_lock(&vq->mutex);
+
+	if (!vhost_vq_get_backend(vq))
+		goto out;
+
+	if (!vq_meta_prefetch(vq))
+		goto out;
+
+	/* Avoid further vmexits, we're already processing the virtqueue */
+	vhost_disable_notify(&vsock->dev, vq);
+
+	do {
+		struct virtio_vsock_hdr *hdr;
+		size_t iov_len, payload_len;
+		struct iov_iter iov_iter;
+		u32 flags_to_restore = 0;
+		struct sk_buff *skb;
+		unsigned out, in;
+		size_t nbytes;
+		int head;
+
+		skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
+
+		if (!skb) {
+			vhost_enable_notify(&vsock->dev, vq);
+			break;
+		}
+
+		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
+					 &out, &in, NULL, NULL);
+		if (head < 0) {
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
+			break;
+		}
+
+		if (head == vq->num) {
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
+			/* We cannot finish yet if more buffers snuck in while
+			 * re-enabling notify.
+			 */
+			if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
+				vhost_disable_notify(&vsock->dev, vq);
+				continue;
+			}
+			break;
+		}
+
+		if (out) {
+			kfree_skb(skb);
+			vq_err(vq, "Expected 0 output buffers, got %u\n", out);
+			break;
+		}
+
+		iov_len = iov_length(&vq->iov[out], in);
+		if (iov_len < sizeof(*hdr)) {
+			kfree_skb(skb);
+			vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
+			break;
+		}
+
+		iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
+		payload_len = skb->len;
+		hdr = virtio_vsock_hdr(skb);
+
+		/* If the packet is greater than the space available in the
+		 * buffer, we split it using multiple buffers.
+		 */
+		if (payload_len > iov_len - sizeof(*hdr)) {
+			payload_len = iov_len - sizeof(*hdr);
+
+			/* As we are copying pieces of large packet's buffer to
+			 * small rx buffers, headers of packets in rx queue are
+			 * created dynamically and are initialized with header
+			 * of current packet(except length). But in case of
+			 * SOCK_SEQPACKET, we also must clear message delimeter
+			 * bit (VIRTIO_VSOCK_SEQ_EOM) and MSG_EOR bit
+			 * (VIRTIO_VSOCK_SEQ_EOR) if set. Otherwise,
+			 * there will be sequence of packets with these
+			 * bits set. After initialized header will be copied to
+			 * rx buffer, these required bits will be restored.
+			 */
+			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
+				hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
+				flags_to_restore |= VIRTIO_VSOCK_SEQ_EOM;
+
+				if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR) {
+					hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
+					flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR;
+				}
+			}
+		}
+
+		/* Set the correct length in the header */
+		hdr->len = cpu_to_le32(payload_len);
+
+		nbytes = copy_to_iter(hdr, sizeof(*hdr), &iov_iter);
+		if (nbytes != sizeof(*hdr)) {
+			kfree_skb(skb);
+			vq_err(vq, "Faulted on copying pkt hdr\n");
+			break;
+		}
+
+		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
+		if (nbytes != payload_len) {
+			kfree_skb(skb);
+			vq_err(vq, "Faulted on copying pkt buf\n");
+			break;
+		}
+
+		/* Deliver to monitoring devices all packets that we
+		 * will transmit.
+		 */
+		virtio_transport_deliver_tap_pkt(skb);
+
+		vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
+		added = true;
+
+		skb_pull(skb, payload_len);
+		total_len += payload_len;
+
+		/* If we didn't send all the payload we can requeue the packet
+		 * to send it with the next available buffer.
+		 */
+		if (skb->len > 0) {
+			hdr->flags |= cpu_to_le32(flags_to_restore);
+
+			/* We are queueing the same skb to handle
+			 * the remaining bytes, and we want to deliver it
+			 * to monitoring devices in the next iteration.
+			 */
+			virtio_vsock_skb_clear_tap_delivered(skb);
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
+		} else {
+			if (virtio_vsock_skb_reply(skb)) {
+				int val;
+
+				val = atomic_dec_return(&vsock->queued_replies);
+
+				/* Do we have resources to resume tx
+				 * processing?
+				 */
+				if (val + 1 == tx_vq->num)
+					restart_tx = true;
+			}
+
+			consume_skb(skb);
+		}
+	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
+	if (added)
+		vhost_signal(&vsock->dev, vq);
+
+out:
+	mutex_unlock(&vq->mutex);
+
+	if (restart_tx)
+		vhost_poll_queue(&tx_vq->poll);
+}
+
+static void vhost_transport_send_pkt_work(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq;
+	struct vhost_vsock *vsock;
+
+	vsock = container_of(work, struct vhost_vsock, send_pkt_work);
+	vq = &vsock->vqs[VSOCK_VQ_RX];
+
+	vhost_transport_do_send_pkt(vsock, vq);
+}
+
+static int
+vhost_transport_send_pkt(struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vhost_vsock *vsock;
+	int len = skb->len;
+
+	rcu_read_lock();
+
+	/* Find the vhost_vsock according to guest context id  */
+	vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid));
+	if (!vsock) {
+		rcu_read_unlock();
+		kfree_skb(skb);
+		return -ENODEV;
+	}
+
+	if (virtio_vsock_skb_reply(skb))
+		atomic_inc(&vsock->queued_replies);
+
+	virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
+	vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
+
+	rcu_read_unlock();
+	return len;
+}
+
+static int
+vhost_transport_cancel_pkt(struct vsock_sock *vsk)
+{
+	struct vhost_vsock *vsock;
+	int cnt = 0;
+	int ret = -ENODEV;
+
+	rcu_read_lock();
+
+	/* Find the vhost_vsock according to guest context id  */
+	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
+	if (!vsock)
+		goto out;
+
+	cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
+
+	if (cnt) {
+		struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
+		int new_cnt;
+
+		new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
+		if (new_cnt + cnt >= tx_vq->num && new_cnt < tx_vq->num)
+			vhost_poll_queue(&tx_vq->poll);
+	}
+
+	ret = 0;
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+static struct sk_buff *
+vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
+		      unsigned int out, unsigned int in)
+{
+	struct virtio_vsock_hdr *hdr;
+	struct iov_iter iov_iter;
+	struct sk_buff *skb;
+	size_t payload_len;
+	size_t nbytes;
+	size_t len;
+
+	if (in != 0) {
+		vq_err(vq, "Expected 0 input buffers, got %u\n", in);
+		return NULL;
+	}
+
+	len = iov_length(vq->iov, out);
+
+	/* len contains both payload and hdr */
+	skb = virtio_vsock_alloc_skb(len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	iov_iter_init(&iov_iter, ITER_SOURCE, vq->iov, out, len);
+
+	hdr = virtio_vsock_hdr(skb);
+	nbytes = copy_from_iter(hdr, sizeof(*hdr), &iov_iter);
+	if (nbytes != sizeof(*hdr)) {
+		vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
+		       sizeof(*hdr), nbytes);
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	payload_len = le32_to_cpu(hdr->len);
+
+	/* No payload */
+	if (!payload_len)
+		return skb;
+
+	/* The pkt is too big or the length in the header is invalid */
+	if (payload_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE ||
+	    payload_len + sizeof(*hdr) > len) {
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	virtio_vsock_skb_rx_put(skb);
+
+	nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
+	if (nbytes != payload_len) {
+		vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
+		       payload_len, nbytes);
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	return skb;
+}
+
+/* Is there space left for replies to rx packets? */
+static bool vhost_vsock_more_replies(struct vhost_vsock *vsock)
+{
+	struct vhost_virtqueue *vq = &vsock->vqs[VSOCK_VQ_TX];
+	int val;
+
+	smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
+	val = atomic_read(&vsock->queued_replies);
+
+	return val < vq->num;
+}
+
+static bool vhost_transport_seqpacket_allow(u32 remote_cid);
+
+static struct virtio_transport vhost_transport = {
+	.transport = {
+		.module                   = THIS_MODULE,
+
+		.get_local_cid            = vhost_transport_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               = vhost_transport_cancel_pkt,
+
+		.dgram_enqueue            = virtio_transport_dgram_enqueue,
+		.dgram_dequeue            = virtio_transport_dgram_dequeue,
+		.dgram_bind               = virtio_transport_dgram_bind,
+		.dgram_allow              = virtio_transport_dgram_allow,
+
+		.stream_enqueue           = virtio_transport_stream_enqueue,
+		.stream_dequeue           = virtio_transport_stream_dequeue,
+		.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          = vhost_transport_seqpacket_allow,
+		.seqpacket_has_data       = virtio_transport_seqpacket_has_data,
+
+		.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,
+
+		.read_skb = virtio_transport_read_skb,
+	},
+
+	.send_pkt = vhost_transport_send_pkt,
+};
+
+static bool vhost_transport_seqpacket_allow(u32 remote_cid)
+{
+	struct vhost_vsock *vsock;
+	bool seqpacket_allow = false;
+
+	rcu_read_lock();
+	vsock = vhost_vsock_get(remote_cid);
+
+	if (vsock)
+		seqpacket_allow = vsock->seqpacket_allow;
+
+	rcu_read_unlock();
+
+	return seqpacket_allow;
+}
+
+static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
+						 dev);
+	int head, pkts = 0, total_len = 0;
+	unsigned int out, in;
+	struct sk_buff *skb;
+	bool added = false;
+
+	mutex_lock(&vq->mutex);
+
+	if (!vhost_vq_get_backend(vq))
+		goto out;
+
+	if (!vq_meta_prefetch(vq))
+		goto out;
+
+	vhost_disable_notify(&vsock->dev, vq);
+	do {
+		struct virtio_vsock_hdr *hdr;
+
+		if (!vhost_vsock_more_replies(vsock)) {
+			/* Stop tx until the device processes already
+			 * pending replies.  Leave tx virtqueue
+			 * callbacks disabled.
+			 */
+			goto no_more_replies;
+		}
+
+		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
+					 &out, &in, NULL, NULL);
+		if (head < 0)
+			break;
+
+		if (head == vq->num) {
+			if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
+				vhost_disable_notify(&vsock->dev, vq);
+				continue;
+			}
+			break;
+		}
+
+		skb = vhost_vsock_alloc_skb(vq, out, in);
+		if (!skb) {
+			vq_err(vq, "Faulted on pkt\n");
+			continue;
+		}
+
+		total_len += sizeof(*hdr) + skb->len;
+
+		/* Deliver to monitoring devices all received packets */
+		virtio_transport_deliver_tap_pkt(skb);
+
+		hdr = virtio_vsock_hdr(skb);
+
+		/* Only accept correctly addressed packets */
+		if (le64_to_cpu(hdr->src_cid) == vsock->guest_cid &&
+		    le64_to_cpu(hdr->dst_cid) ==
+		    vhost_transport_get_local_cid())
+			virtio_transport_recv_pkt(&vhost_transport, skb);
+		else
+			kfree_skb(skb);
+
+		vhost_add_used(vq, head, 0);
+		added = true;
+	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
+
+no_more_replies:
+	if (added)
+		vhost_signal(&vsock->dev, vq);
+
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static void vhost_vsock_handle_rx_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						poll.work);
+	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
+						 dev);
+
+	vhost_transport_do_send_pkt(vsock, vq);
+}
+
+static int vhost_vsock_start(struct vhost_vsock *vsock)
+{
+	struct vhost_virtqueue *vq;
+	size_t i;
+	int ret;
+
+	mutex_lock(&vsock->dev.mutex);
+
+	ret = vhost_dev_check_owner(&vsock->dev);
+	if (ret)
+		goto err;
+
+	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
+		vq = &vsock->vqs[i];
+
+		mutex_lock(&vq->mutex);
+
+		if (!vhost_vq_access_ok(vq)) {
+			ret = -EFAULT;
+			goto err_vq;
+		}
+
+		if (!vhost_vq_get_backend(vq)) {
+			vhost_vq_set_backend(vq, vsock);
+			ret = vhost_vq_init_access(vq);
+			if (ret)
+				goto err_vq;
+		}
+
+		mutex_unlock(&vq->mutex);
+	}
+
+	/* Some packets may have been queued before the device was started,
+	 * let's kick the send worker to send them.
+	 */
+	vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
+
+	mutex_unlock(&vsock->dev.mutex);
+	return 0;
+
+err_vq:
+	vhost_vq_set_backend(vq, NULL);
+	mutex_unlock(&vq->mutex);
+
+	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
+		vq = &vsock->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vhost_vq_set_backend(vq, NULL);
+		mutex_unlock(&vq->mutex);
+	}
+err:
+	mutex_unlock(&vsock->dev.mutex);
+	return ret;
+}
+
+static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
+{
+	size_t i;
+	int ret = 0;
+
+	mutex_lock(&vsock->dev.mutex);
+
+	if (check_owner) {
+		ret = vhost_dev_check_owner(&vsock->dev);
+		if (ret)
+			goto err;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
+		struct vhost_virtqueue *vq = &vsock->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vhost_vq_set_backend(vq, NULL);
+		mutex_unlock(&vq->mutex);
+	}
+
+err:
+	mutex_unlock(&vsock->dev.mutex);
+	return ret;
+}
+
+static void vhost_vsock_free(struct vhost_vsock *vsock)
+{
+	kvfree(vsock);
+}
+
+static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
+{
+	struct vhost_virtqueue **vqs;
+	struct vhost_vsock *vsock;
+	int ret;
+
+	/* This struct is large and allocation could fail, fall back to vmalloc
+	 * if there is no other way.
+	 */
+	vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (!vsock)
+		return -ENOMEM;
+
+	vqs = kmalloc_array(ARRAY_SIZE(vsock->vqs), sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	vsock->guest_cid = 0; /* no CID assigned yet */
+
+	atomic_set(&vsock->queued_replies, 0);
+
+	vqs[VSOCK_VQ_TX] = &vsock->vqs[VSOCK_VQ_TX];
+	vqs[VSOCK_VQ_RX] = &vsock->vqs[VSOCK_VQ_RX];
+	vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;
+	vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;
+
+	vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
+		       UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
+		       VHOST_VSOCK_WEIGHT, true, NULL);
+
+	file->private_data = vsock;
+	skb_queue_head_init(&vsock->send_pkt_queue);
+	vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
+	return 0;
+
+out:
+	vhost_vsock_free(vsock);
+	return ret;
+}
+
+static void vhost_vsock_flush(struct vhost_vsock *vsock)
+{
+	vhost_dev_flush(&vsock->dev);
+}
+
+static void vhost_vsock_reset_orphans(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(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.
+	 */
+
+	/* If the peer is still valid, no need to reset connection */
+	if (vhost_vsock_get(vsk->remote_addr.svm_cid))
+		return;
+
+	/* If the close timeout is pending, let it expire.  This avoids races
+	 * with the timeout callback.
+	 */
+	if (vsk->close_work_scheduled)
+		return;
+
+	sock_set_flag(sk, SOCK_DONE);
+	vsk->peer_shutdown = SHUTDOWN_MASK;
+	sk->sk_state = SS_UNCONNECTED;
+	sk->sk_err = ECONNRESET;
+	sk_error_report(sk);
+}
+
+static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
+{
+	struct vhost_vsock *vsock = file->private_data;
+
+	mutex_lock(&vhost_vsock_mutex);
+	if (vsock->guest_cid)
+		hash_del_rcu(&vsock->hash);
+	mutex_unlock(&vhost_vsock_mutex);
+
+	/* Wait for other CPUs to finish using vsock */
+	synchronize_rcu();
+
+	/* Iterating over all connections for all CIDs to find orphans is
+	 * inefficient.  Room for improvement here. */
+	vsock_for_each_connected_socket(&vhost_transport.transport,
+					vhost_vsock_reset_orphans);
+
+	/* Don't check the owner, because we are in the release path, so we
+	 * need to stop the vsock device in any case.
+	 * vhost_vsock_stop() can not fail in this case, so we don't need to
+	 * check the return code.
+	 */
+	vhost_vsock_stop(vsock, false);
+	vhost_vsock_flush(vsock);
+	vhost_dev_stop(&vsock->dev);
+
+	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
+
+	vhost_dev_cleanup(&vsock->dev);
+	kfree(vsock->dev.vqs);
+	vhost_vsock_free(vsock);
+	return 0;
+}
+
+static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
+{
+	struct vhost_vsock *other;
+
+	/* Refuse reserved CIDs */
+	if (guest_cid <= VMADDR_CID_HOST ||
+	    guest_cid == U32_MAX)
+		return -EINVAL;
+
+	/* 64-bit CIDs are not yet supported */
+	if (guest_cid > U32_MAX)
+		return -EINVAL;
+
+	/* Refuse if CID is assigned to the guest->host transport (i.e. nested
+	 * VM), to make the loopback work.
+	 */
+	if (vsock_find_cid(guest_cid))
+		return -EADDRINUSE;
+
+	/* Refuse if CID is already in use */
+	mutex_lock(&vhost_vsock_mutex);
+	other = vhost_vsock_get(guest_cid);
+	if (other && other != vsock) {
+		mutex_unlock(&vhost_vsock_mutex);
+		return -EADDRINUSE;
+	}
+
+	if (vsock->guest_cid)
+		hash_del_rcu(&vsock->hash);
+
+	vsock->guest_cid = guest_cid;
+	hash_add_rcu(vhost_vsock_hash, &vsock->hash, vsock->guest_cid);
+	mutex_unlock(&vhost_vsock_mutex);
+
+	return 0;
+}
+
+static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
+{
+	struct vhost_virtqueue *vq;
+	int i;
+
+	if (features & ~VHOST_VSOCK_FEATURES)
+		return -EOPNOTSUPP;
+
+	mutex_lock(&vsock->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&vsock->dev)) {
+		goto err;
+	}
+
+	if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
+		if (vhost_init_device_iotlb(&vsock->dev))
+			goto err;
+	}
+
+	if (features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET))
+		vsock->seqpacket_allow = true;
+
+	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
+		vq = &vsock->vqs[i];
+		mutex_lock(&vq->mutex);
+		vq->acked_features = features;
+		mutex_unlock(&vq->mutex);
+	}
+	mutex_unlock(&vsock->dev.mutex);
+	return 0;
+
+err:
+	mutex_unlock(&vsock->dev.mutex);
+	return -EFAULT;
+}
+
+static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
+				  unsigned long arg)
+{
+	struct vhost_vsock *vsock = f->private_data;
+	void __user *argp = (void __user *)arg;
+	u64 guest_cid;
+	u64 features;
+	int start;
+	int r;
+
+	switch (ioctl) {
+	case VHOST_VSOCK_SET_GUEST_CID:
+		if (copy_from_user(&guest_cid, argp, sizeof(guest_cid)))
+			return -EFAULT;
+		return vhost_vsock_set_cid(vsock, guest_cid);
+	case VHOST_VSOCK_SET_RUNNING:
+		if (copy_from_user(&start, argp, sizeof(start)))
+			return -EFAULT;
+		if (start)
+			return vhost_vsock_start(vsock);
+		else
+			return vhost_vsock_stop(vsock, true);
+	case VHOST_GET_FEATURES:
+		features = VHOST_VSOCK_FEATURES;
+		if (copy_to_user(argp, &features, sizeof(features)))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_FEATURES:
+		if (copy_from_user(&features, argp, sizeof(features)))
+			return -EFAULT;
+		return vhost_vsock_set_features(vsock, features);
+	case VHOST_GET_BACKEND_FEATURES:
+		features = VHOST_VSOCK_BACKEND_FEATURES;
+		if (copy_to_user(argp, &features, sizeof(features)))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_BACKEND_FEATURES:
+		if (copy_from_user(&features, argp, sizeof(features)))
+			return -EFAULT;
+		if (features & ~VHOST_VSOCK_BACKEND_FEATURES)
+			return -EOPNOTSUPP;
+		vhost_set_backend_features(&vsock->dev, features);
+		return 0;
+	default:
+		mutex_lock(&vsock->dev.mutex);
+		r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vring_ioctl(&vsock->dev, ioctl, argp);
+		else
+			vhost_vsock_flush(vsock);
+		mutex_unlock(&vsock->dev.mutex);
+		return r;
+	}
+}
+
+static ssize_t vhost_vsock_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct vhost_vsock *vsock = file->private_data;
+	struct vhost_dev *dev = &vsock->dev;
+	int noblock = file->f_flags & O_NONBLOCK;
+
+	return vhost_chr_read_iter(dev, to, noblock);
+}
+
+static ssize_t vhost_vsock_chr_write_iter(struct kiocb *iocb,
+					struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct vhost_vsock *vsock = file->private_data;
+	struct vhost_dev *dev = &vsock->dev;
+
+	return vhost_chr_write_iter(dev, from);
+}
+
+static __poll_t vhost_vsock_chr_poll(struct file *file, poll_table *wait)
+{
+	struct vhost_vsock *vsock = file->private_data;
+	struct vhost_dev *dev = &vsock->dev;
+
+	return vhost_chr_poll(file, dev, wait);
+}
+
+static const struct file_operations vhost_vsock_fops = {
+	.owner          = THIS_MODULE,
+	.open           = vhost_vsock_dev_open,
+	.release        = vhost_vsock_dev_release,
+	.llseek		= noop_llseek,
+	.unlocked_ioctl = vhost_vsock_dev_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+	.read_iter      = vhost_vsock_chr_read_iter,
+	.write_iter     = vhost_vsock_chr_write_iter,
+	.poll           = vhost_vsock_chr_poll,
+};
+
+static struct miscdevice vhost_vsock_misc = {
+	.minor = VHOST_VSOCK_MINOR,
+	.name = "vhost-vsock",
+	.fops = &vhost_vsock_fops,
+};
+
+static int __init vhost_vsock_init(void)
+{
+	int ret;
+
+	ret = vsock_core_register(&vhost_transport.transport,
+				  VSOCK_TRANSPORT_F_H2G);
+	if (ret < 0)
+		return ret;
+
+	ret = misc_register(&vhost_vsock_misc);
+	if (ret) {
+		vsock_core_unregister(&vhost_transport.transport);
+		return ret;
+	}
+
+	return 0;
+};
+
+static void __exit vhost_vsock_exit(void)
+{
+	misc_deregister(&vhost_vsock_misc);
+	vsock_core_unregister(&vhost_transport.transport);
+};
+
+module_init(vhost_vsock_init);
+module_exit(vhost_vsock_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Asias He");
+MODULE_DESCRIPTION("vhost transport for vsock ");
+MODULE_ALIAS_MISCDEV(VHOST_VSOCK_MINOR);
+MODULE_ALIAS("devname:vhost-vsock");