Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 2529 insertions, 0 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
new file mode 100644
index 000000000..4ce9f00ae
--- /dev/null
+++ b/drivers/vhost/scsi.c
@@ -0,0 +1,2529 @@
+/*******************************************************************************
+ * Vhost kernel TCM fabric driver for virtio SCSI initiators
+ *
+ * (C) Copyright 2010-2013 Datera, Inc.
+ * (C) Copyright 2010-2012 IBM Corp.
+ *
+ * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
+ *
+ * Authors: Nicholas A. Bellinger <nab@daterainc.com>
+ *          Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ ****************************************************************************/
+
+#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 <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_submission_work() */
+	u32 tvc_lun;
+	/* 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;
+	/* work item used for cmwq dispatch to vhost_scsi_submission_work() */
+	struct work_struct work;
+	/* 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 list_head tmf_queue;
+};
+
+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_VQ	128
+#define VHOST_SCSI_MAX_EVENT	128
+
+struct vhost_scsi_virtqueue {
+	struct vhost_virtqueue vq;
+	/*
+	 * 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_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[VHOST_SCSI_MAX_VQ];
+
+	struct vhost_work vs_completion_work; /* cmd completion work item */
+	struct llist_head vs_completion_list; /* cmd completion queue */
+
+	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_tpg *tpg;
+	struct vhost_scsi *vhost;
+	struct vhost_scsi_virtqueue *svq;
+	struct list_head queue_entry;
+
+	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;
+};
+
+static struct workqueue_struct *vhost_scsi_workqueue;
+
+/* Global spinlock to protect vhost_scsi TPG list for vhost IOCTL access */
+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 < VHOST_SCSI_MAX_VQ; 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 int vhost_scsi_check_false(struct se_portal_group *se_tpg)
+{
+	return 0;
+}
+
+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 u32 vhost_scsi_tpg_get_inst_index(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+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++)
+			put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+	}
+	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_tpg *tpg = tmf->tpg;
+	struct vhost_scsi_inflight *inflight = tmf->inflight;
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	list_add_tail(&tpg->tmf_queue, &tmf->queue_entry);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+	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);
+
+		vhost_work_queue(&tmf->vhost->dev, &tmf->vwork);
+	} else {
+		struct vhost_scsi_cmd *cmd = container_of(se_cmd,
+					struct vhost_scsi_cmd, tvc_se_cmd);
+		struct vhost_scsi *vs = cmd->tvc_vhost;
+
+		llist_add(&cmd->tvc_completion_list, &vs->vs_completion_list);
+		vhost_work_queue(&vs->dev, &vs->vs_completion_work);
+	}
+}
+
+static u32 vhost_scsi_sess_get_index(struct se_session *se_sess)
+{
+	return 0;
+}
+
+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 void vhost_scsi_set_default_node_attrs(struct se_node_acl *nacl)
+{
+	return;
+}
+
+static int vhost_scsi_get_cmd_state(struct se_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);
+}
+
+/* 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 *vs = container_of(work, struct vhost_scsi,
+					vs_completion_work);
+	DECLARE_BITMAP(signal, VHOST_SCSI_MAX_VQ);
+	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;
+	int ret, vq;
+
+	bitmap_zero(signal, VHOST_SCSI_MAX_VQ);
+	llnode = llist_del_all(&vs->vs_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));
+		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, READ, &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))) {
+			struct vhost_scsi_virtqueue *q;
+			vhost_add_used(cmd->tvc_vq, cmd->tvc_vq_desc, 0);
+			q = container_of(cmd->tvc_vq, struct vhost_scsi_virtqueue, vq);
+			vq = q - vs->vqs;
+			__set_bit(vq, signal);
+		} else
+			pr_err("Faulted on virtio_scsi_cmd_resp\n");
+
+		vhost_scsi_release_cmd_res(se_cmd);
+	}
+
+	vq = -1;
+	while ((vq = find_next_bit(signal, VHOST_SCSI_MAX_VQ, vq + 1))
+		< VHOST_SCSI_MAX_VQ)
+		vhost_signal(&vs->dev, &vs->vqs[vq].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 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, 0, false);
+	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;
+	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);
+
+	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 write)
+{
+	struct page **pages = cmd->tvc_upages;
+	struct scatterlist *sg = sgl;
+	ssize_t bytes;
+	size_t offset;
+	unsigned int npages = 0;
+
+	bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
+				VHOST_SCSI_PREALLOC_UPAGES, &offset);
+	/* No pages were pinned */
+	if (bytes <= 0)
+		return bytes < 0 ? bytes : -EFAULT;
+
+	iov_iter_advance(iter, bytes);
+
+	while (bytes) {
+		unsigned n = min_t(unsigned, PAGE_SIZE - offset, bytes);
+		sg_set_page(sg++, pages[npages++], n, offset);
+		bytes -= n;
+		offset = 0;
+	}
+	return npages;
+}
+
+static int
+vhost_scsi_calc_sgls(struct iov_iter *iter, size_t bytes, int max_sgls)
+{
+	int sgl_count = 0;
+
+	if (!iter || !iter->iov) {
+		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_iov_to_sgl(struct vhost_scsi_cmd *cmd, bool write,
+		      struct iov_iter *iter,
+		      struct scatterlist *sg, int sg_count)
+{
+	struct scatterlist *p = sg;
+	int ret;
+
+	while (iov_iter_count(iter)) {
+		ret = vhost_scsi_map_to_sgl(cmd, iter, sg, write);
+		if (ret < 0) {
+			while (p < sg) {
+				struct page *page = sg_page(p++);
+				if (page)
+					put_page(page);
+			}
+			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;
+	bool write = (cmd->tvc_data_direction == DMA_FROM_DEVICE);
+
+	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_iov_to_sgl(cmd, write, prot_iter,
+					    cmd->tvc_prot_sgl,
+					    cmd->tvc_prot_sgl_count);
+		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_iov_to_sgl(cmd, write, 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_submission_work(struct work_struct *work)
+{
+	struct vhost_scsi_cmd *cmd =
+		container_of(work, struct vhost_scsi_cmd, work);
+	struct vhost_scsi_nexus *tv_nexus;
+	struct se_cmd *se_cmd = &cmd->tvc_se_cmd;
+	struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
+	int rc;
+
+	/* 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;
+	rc = target_submit_cmd_map_sgls(se_cmd, tv_nexus->tvn_se_sess,
+			cmd->tvc_cdb, &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,
+			sg_ptr, cmd->tvc_sgl_count, NULL, 0, sg_prot_ptr,
+			cmd->tvc_prot_sgl_count);
+	if (rc < 0) {
+		transport_send_check_condition_and_sense(se_cmd,
+				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+	}
+}
+
+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, WRITE, 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, 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, READ, &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;
+		cmd->tvc_resp_iov = vq->iov[vc.out];
+		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;
+		/*
+		 * Dispatch cmd descriptor for cmwq execution in process
+		 * context provided by vhost_scsi_workqueue.  This also ensures
+		 * cmd is executed on the same kworker CPU as this vhost
+		 * thread to gain positive L2 cache locality effects.
+		 */
+		INIT_WORK(&cmd->work, vhost_scsi_submission_work);
+		queue_work(vhost_scsi_workqueue, &cmd->work);
+		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, READ, 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);
+	int resp_code;
+
+	if (tmf->scsi_resp == TMR_FUNCTION_COMPLETE)
+		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;
+	}
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	if (list_empty(&tpg->tmf_queue)) {
+		pr_err("Missing reserve TMF. Could not handle LUN RESET.\n");
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		goto send_reject;
+	}
+
+	tmf = list_first_entry(&tpg->tmf_queue, struct vhost_scsi_tmf,
+			       queue_entry);
+	list_del_init(&tmf->queue_entry);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	tmf->tpg = tpg;
+	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, READ, &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_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_work_queue(&vs->dev, &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, 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);
+}
+
+static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index)
+{
+	vhost_poll_flush(&vs->vqs[index].vq.poll);
+}
+
+/* Callers must hold dev mutex */
+static void vhost_scsi_flush(struct vhost_scsi *vs)
+{
+	struct vhost_scsi_inflight *old_inflight[VHOST_SCSI_MAX_VQ];
+	int i;
+
+	/* Init new inflight and remember the old inflight */
+	vhost_scsi_init_inflight(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 < VHOST_SCSI_MAX_VQ; i++)
+		kref_put(&old_inflight[i]->kref, vhost_scsi_done_inflight);
+
+	/* Flush both the vhost poll and vhost work */
+	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
+		vhost_scsi_flush_vq(vs, i);
+	vhost_work_flush(&vs->dev, &vs->vs_completion_work);
+	vhost_work_flush(&vs->dev, &vs->vs_event_work);
+
+	/* Wait for all reqs issued before the flush to be finished */
+	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
+		wait_for_completion(&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);
+	}
+
+	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))
+		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_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:
+ *    vhost_scsi_mutex -> vs->dev.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(&vhost_scsi_mutex);
+	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);
+
+	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);
+				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);
+				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);
+	}
+
+	if (match) {
+		memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
+		       sizeof(vs->vs_vhost_wwpn));
+
+		for (i = VHOST_SCSI_VQ_IO; i < VHOST_SCSI_MAX_VQ; 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 < VHOST_SCSI_MAX_VQ; 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) {
+			tpg->tv_tpg_vhost_count--;
+			target_undepend_item(&tpg->se_tpg.tpg_group.cg_item);
+		}
+	}
+	kfree(vs_tpg);
+out:
+	mutex_unlock(&vs->dev.mutex);
+	mutex_unlock(&vhost_scsi_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(&vhost_scsi_mutex);
+	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;
+
+		mutex_lock(&tpg->tv_tpg_mutex);
+		tv_tport = tpg->tport;
+		if (!tv_tport) {
+			ret = -ENODEV;
+			goto err_tpg;
+		}
+
+		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_tpg;
+		}
+		tpg->tv_tpg_vhost_count--;
+		tpg->vhost_scsi = NULL;
+		vs->vs_tpg[target] = NULL;
+		match = true;
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		/*
+		 * Release se_tpg->tpg_group.cg_item configfs dependency now
+		 * to allow vhost-scsi WWPN se_tpg->tpg_group shutdown to occur.
+		 */
+		se_tpg = &tpg->se_tpg;
+		target_undepend_item(&se_tpg->tpg_group.cg_item);
+	}
+	if (match) {
+		for (i = 0; i < VHOST_SCSI_MAX_VQ; 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);
+			vhost_scsi_destroy_vq_cmds(vq);
+		}
+	}
+	/*
+	 * 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);
+	mutex_unlock(&vhost_scsi_mutex);
+	return 0;
+
+err_tpg:
+	mutex_unlock(&tpg->tv_tpg_mutex);
+err_dev:
+	mutex_unlock(&vs->dev.mutex);
+	mutex_unlock(&vhost_scsi_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 < VHOST_SCSI_MAX_VQ; 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 *vs;
+	struct vhost_virtqueue **vqs;
+	int r = -ENOMEM, i;
+
+	vs = kzalloc(sizeof(*vs), GFP_KERNEL | __GFP_NOWARN | __GFP_RETRY_MAYFAIL);
+	if (!vs) {
+		vs = vzalloc(sizeof(*vs));
+		if (!vs)
+			goto err_vs;
+	}
+
+	vqs = kmalloc_array(VHOST_SCSI_MAX_VQ, sizeof(*vqs), GFP_KERNEL);
+	if (!vqs)
+		goto err_vqs;
+
+	vhost_work_init(&vs->vs_completion_work, vhost_scsi_complete_cmd_work);
+	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 < VHOST_SCSI_MAX_VQ; i++) {
+		vqs[i] = &vs->vqs[i].vq;
+		vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;
+	}
+	vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV,
+		       VHOST_SCSI_WEIGHT, 0, true, NULL);
+
+	vhost_scsi_init_inflight(vs, NULL);
+
+	f->private_data = vs;
+	return 0;
+
+err_vqs:
+	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);
+	/* Jobs can re-queue themselves in evt kick handler. Do extra flush. */
+	vhost_scsi_flush(vs);
+	kfree(vs->dev.vqs);
+	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);
+	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;
+
+	mutex_lock(&vs->dev.mutex);
+
+	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);
+	if (vhost_has_feature(vq, VIRTIO_SCSI_F_HOTPLUG))
+		vhost_scsi_send_evt(vs, tpg, lun,
+				   VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
+	mutex_unlock(&vq->mutex);
+	mutex_unlock(&vs->dev.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);
+	struct vhost_scsi_tmf *tmf;
+
+	tmf = kzalloc(sizeof(*tmf), GFP_KERNEL);
+	if (!tmf)
+		return -ENOMEM;
+	INIT_LIST_HEAD(&tmf->queue_entry);
+	vhost_work_init(&tmf->vwork, vhost_scsi_tmf_resp_work);
+
+	mutex_lock(&vhost_scsi_mutex);
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tpg->tv_tpg_port_count++;
+	list_add_tail(&tmf->queue_entry, &tpg->tmf_queue);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	vhost_scsi_hotplug(tpg, lun);
+
+	mutex_unlock(&vhost_scsi_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);
+	struct vhost_scsi_tmf *tmf;
+
+	mutex_lock(&vhost_scsi_mutex);
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tpg->tv_tpg_port_count--;
+	tmf = list_first_entry(&tpg->tmf_queue, struct vhost_scsi_tmf,
+			       queue_entry);
+	list_del(&tmf->queue_entry);
+	kfree(tmf);
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	vhost_scsi_hotunplug(tpg, lun);
+
+	mutex_unlock(&vhost_scsi_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 sprintf(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 = snprintf(page, PAGE_SIZE, "%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);
+	INIT_LIST_HEAD(&tpg->tmf_queue);
+	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 sprintf(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_demo_mode_write_protect = vhost_scsi_check_false,
+	.tpg_check_prod_mode_write_protect = vhost_scsi_check_false,
+	.tpg_check_prot_fabric_only	= vhost_scsi_check_prot_fabric_only,
+	.tpg_get_inst_index		= vhost_scsi_tpg_get_inst_index,
+	.release_cmd			= vhost_scsi_release_cmd,
+	.check_stop_free		= vhost_scsi_check_stop_free,
+	.sess_get_index			= vhost_scsi_sess_get_index,
+	.sess_get_initiator_sid		= NULL,
+	.write_pending			= vhost_scsi_write_pending,
+	.set_default_node_attributes	= vhost_scsi_set_default_node_attrs,
+	.get_cmd_state			= vhost_scsi_get_cmd_state,
+	.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);
+
+	/*
+	 * Use our own dedicated workqueue for submitting I/O into
+	 * target core to avoid contention within system_wq.
+	 */
+	vhost_scsi_workqueue = alloc_workqueue("vhost_scsi", 0, 0);
+	if (!vhost_scsi_workqueue)
+		goto out;
+
+	ret = vhost_scsi_register();
+	if (ret < 0)
+		goto out_destroy_workqueue;
+
+	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_destroy_workqueue:
+	destroy_workqueue(vhost_scsi_workqueue);
+out:
+	return ret;
+};
+
+static void vhost_scsi_exit(void)
+{
+	target_unregister_template(&vhost_scsi_ops);
+	vhost_scsi_deregister();
+	destroy_workqueue(vhost_scsi_workqueue);
+};
+
+MODULE_DESCRIPTION("VHOST_SCSI series fabric driver");
+MODULE_ALIAS("tcm_vhost");
+MODULE_LICENSE("GPL");
+module_init(vhost_scsi_init);
+module_exit(vhost_scsi_exit);