Linux Virtualization - Jul 2012 - [RFC-v5] tcm_vhost: Initial merge for vhost level target fabric driver

From: Nicholas Bellinger <nab at linux-iscsi.org>

Hello KVM + QEMU folks,

This is -v5 of the in-flight tcm_vhost fabric driver for KVM host virtualized
target support using the in-kernel storage stack with for-3.6 code.

The changes since -v4 have been pretty minimal.  A new GET_ABI_VERSION ioctl
has been added as requested by Anthony & Co, and after some back <->
forth on
the lists we've decided upon a starting point of VHOST_SCSI_ABI_VERSION=0,
and vhost-scsi RFC userspace has been updated accordingly.

Along with that, a few handfuls of vq related error messages where converted
to use vq_err as requested by MST, along with some minor checkpatch fixes.

So this point everything required to run tcm_vhost from drivers/target +
drivers/vhost, and virtio-scsi LLD bugfix has been merged into v3.6-rc0 code.

Please have a look and let us know if there are any last-minute pre-merge
comments ahead of MST returning from holiday this weekend.

Thank you!

--nab

Changelog v4 -> v5:

  Expose ABI version via VHOST_SCSI_GET_ABI_VERSION + use Rev 0 as
  starting point for v3.6-rc code (Stefan + ALiguori + nab)
  Convert vhost_scsi_handle_vq() to vq_err() (nab + MST)
  Minor style fixes from checkpatch (nab)

Changelog v3 -> v4:

  Rename vhost_vring_target -> vhost_scsi_target (mst + nab)
  Use TRANSPORT_IQN_LEN in vhost_scsi_target->vhost_wwpn[] def (nab)
  Move back to drivers/vhost/, and just use drivers/vhost/Kconfig.tcm (mst)
  Move TCM_VHOST related ioctl defines from include/linux/vhost.h ->
  drivers/vhost/tcm_vhost.h as requested by MST (nab)
  Move Kbuild.tcm include from drivers/staging -> drivers/vhost/, and
  just use 'if STAGING' around 'source drivers/vhost/Kbuild.tcm'

Changelog v2 -> v3:

  Unlock on error in tcm_vhost_drop_nexus() (DanC)
  Fix strlen() doesn't count the terminator (DanC)
  Call kfree() on an error path (DanC)
  Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
  Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
  Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
  as requested by MST (nab)

Changelog v1 -> v2:

  Fix tv_cmd completion -> release SGL memory leak (nab)
  Fix sparse warnings for static variable usage ((Fengguang Wu)
  Fix sparse warnings for min() typing + printk format specs (Fengguang Wu)
  Convert to cmwq submission for I/O dispatch (nab + hch)

Changelog v0 -> v1:

  Merge into single source + header file, and move to drivers/vhost/

Cc: Michael S. Tsirkin <mst at redhat.com>
Cc: Stefan Hajnoczi <stefanha at linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori at us.ibm.com>
Cc: Zhi Yong Wu <wuzhy at cn.ibm.com>
Cc: Paolo Bonzini <pbonzini at redhat.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Hannes Reinecke <hare at suse.de>
Cc: Jens Axboe <axboe at kernel.dk>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
---
 drivers/vhost/Kconfig     |    3 +
 drivers/vhost/Kconfig.tcm |    6 +
 drivers/vhost/Makefile    |    2 +
 drivers/vhost/tcm_vhost.c | 1628 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/vhost/tcm_vhost.h |  101 +++
 5 files changed, 1740 insertions(+), 0 deletions(-)
 create mode 100644 drivers/vhost/Kconfig.tcm
 create mode 100644 drivers/vhost/tcm_vhost.c
 create mode 100644 drivers/vhost/tcm_vhost.h

diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index e4e2fd1..202bba6 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -9,3 +9,6 @@ config VHOST_NET
 	  To compile this driver as a module, choose M here: the module will
 	  be called vhost_net.
 
+if STAGING
+source "drivers/vhost/Kconfig.tcm"
+endif
diff --git a/drivers/vhost/Kconfig.tcm b/drivers/vhost/Kconfig.tcm
new file mode 100644
index 0000000..a9c6f76
--- /dev/null
+++ b/drivers/vhost/Kconfig.tcm
@@ -0,0 +1,6 @@
+config TCM_VHOST
+	tristate "TCM_VHOST fabric module (EXPERIMENTAL)"
+	depends on TARGET_CORE && EVENTFD && EXPERIMENTAL && m
+	default n
+	---help---
+	Say M here to enable the TCM_VHOST fabric module for use with virtio-scsi
guests
diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
index 72dd020..a27b053 100644
--- a/drivers/vhost/Makefile
+++ b/drivers/vhost/Makefile
@@ -1,2 +1,4 @@
 obj-$(CONFIG_VHOST_NET) += vhost_net.o
 vhost_net-y := vhost.o net.o
+
+obj-$(CONFIG_TCM_VHOST) += tcm_vhost.o
diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
new file mode 100644
index 0000000..fb36654
--- /dev/null
+++ b/drivers/vhost/tcm_vhost.c
@@ -0,0 +1,1628 @@
+/*******************************************************************************
+ * Vhost kernel TCM fabric driver for virtio SCSI initiators
+ *
+ * (C) Copyright 2010-2012 RisingTide Systems LLC.
+ * (C) Copyright 2010-2012 IBM Corp.
+ *
+ * Licensed to the Linux Foundation under the General Public License (GPL)
version 2.
+ *
+ * Authors: Nicholas A. Bellinger <nab at risingtidesystems.com>
+ *          Stefan Hajnoczi <stefanha at 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/vhost.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <asm/unaligned.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_tcq.h>
+#include <target/target_core_base.h>
+#include <target/target_core_fabric.h>
+#include <target/target_core_fabric_configfs.h>
+#include <target/target_core_configfs.h>
+#include <target/configfs_macros.h>
+#include <linux/vhost.h>
+#include <linux/virtio_net.h> /* TODO vhost.h currently depends on this
*/
+#include <linux/virtio_scsi.h>
+
+#include "vhost.c"
+#include "vhost.h"
+#include "tcm_vhost.h"
+
+struct vhost_scsi {
+	atomic_t vhost_ref_cnt;
+	struct tcm_vhost_tpg *vs_tpg;
+	struct vhost_dev dev;
+	struct vhost_virtqueue vqs[3];
+
+	struct vhost_work vs_completion_work; /* cmd completion work item */
+	struct list_head vs_completion_list;  /* cmd completion queue */
+	spinlock_t vs_completion_lock;        /* protects s_completion_list */
+};
+
+/* Local pointer to allocated TCM configfs fabric module */
+static struct target_fabric_configfs *tcm_vhost_fabric_configfs;
+
+static struct workqueue_struct *tcm_vhost_workqueue;
+
+/* Global spinlock to protect tcm_vhost TPG list for vhost IOCTL access */
+static DEFINE_MUTEX(tcm_vhost_mutex);
+static LIST_HEAD(tcm_vhost_list);
+
+static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static int tcm_vhost_check_false(struct se_portal_group *se_tpg)
+{
+	return 0;
+}
+
+static char *tcm_vhost_get_fabric_name(void)
+{
+	return "vhost";
+}
+
+static u8 tcm_vhost_get_fabric_proto_ident(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_get_fabric_proto_ident(se_tpg);
+	case SCSI_PROTOCOL_FCP:
+		return fc_get_fabric_proto_ident(se_tpg);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_get_fabric_proto_ident(se_tpg);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_get_fabric_proto_ident(se_tpg);
+}
+
+static char *tcm_vhost_get_fabric_wwn(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	return &tport->tport_name[0];
+}
+
+static u16 tcm_vhost_get_tag(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	return tpg->tport_tpgt;
+}
+
+static u32 tcm_vhost_get_default_depth(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static u32 tcm_vhost_get_pr_transport_id(
+	struct se_portal_group *se_tpg,
+	struct se_node_acl *se_nacl,
+	struct t10_pr_registration *pr_reg,
+	int *format_code,
+	unsigned char *buf)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+					format_code, buf);
+	case SCSI_PROTOCOL_FCP:
+		return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+					format_code, buf);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+					format_code, buf);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+			format_code, buf);
+}
+
+static u32 tcm_vhost_get_pr_transport_id_len(
+	struct se_portal_group *se_tpg,
+	struct se_node_acl *se_nacl,
+	struct t10_pr_registration *pr_reg,
+	int *format_code)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+					format_code);
+	case SCSI_PROTOCOL_FCP:
+		return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+					format_code);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+					format_code);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+			format_code);
+}
+
+static char *tcm_vhost_parse_pr_out_transport_id(
+	struct se_portal_group *se_tpg,
+	const char *buf,
+	u32 *out_tid_len,
+	char **port_nexus_ptr)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+					port_nexus_ptr);
+	case SCSI_PROTOCOL_FCP:
+		return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+					port_nexus_ptr);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+					port_nexus_ptr);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+			port_nexus_ptr);
+}
+
+static struct se_node_acl *tcm_vhost_alloc_fabric_acl(
+	struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_nacl *nacl;
+
+	nacl = kzalloc(sizeof(struct tcm_vhost_nacl), GFP_KERNEL);
+	if (!nacl) {
+		pr_err("Unable to alocate struct tcm_vhost_nacl\n");
+		return NULL;
+	}
+
+	return &nacl->se_node_acl;
+}
+
+static void tcm_vhost_release_fabric_acl(
+	struct se_portal_group *se_tpg,
+	struct se_node_acl *se_nacl)
+{
+	struct tcm_vhost_nacl *nacl = container_of(se_nacl,
+			struct tcm_vhost_nacl, se_node_acl);
+	kfree(nacl);
+}
+
+static u32 tcm_vhost_tpg_get_inst_index(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
+{
+	return;
+}
+
+static int tcm_vhost_shutdown_session(struct se_session *se_sess)
+{
+	return 0;
+}
+
+static void tcm_vhost_close_session(struct se_session *se_sess)
+{
+	return;
+}
+
+static u32 tcm_vhost_sess_get_index(struct se_session *se_sess)
+{
+	return 0;
+}
+
+static int tcm_vhost_write_pending(struct se_cmd *se_cmd)
+{
+	/* Go ahead and process the write immediately */
+	target_execute_cmd(se_cmd);
+	return 0;
+}
+
+static int tcm_vhost_write_pending_status(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static void tcm_vhost_set_default_node_attrs(struct se_node_acl *nacl)
+{
+	return;
+}
+
+static u32 tcm_vhost_get_task_tag(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static int tcm_vhost_get_cmd_state(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *);
+
+static int tcm_vhost_queue_data_in(struct se_cmd *se_cmd)
+{
+	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
+				struct tcm_vhost_cmd, tvc_se_cmd);
+	vhost_scsi_complete_cmd(tv_cmd);
+	return 0;
+}
+
+static int tcm_vhost_queue_status(struct se_cmd *se_cmd)
+{
+	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
+				struct tcm_vhost_cmd, tvc_se_cmd);
+	vhost_scsi_complete_cmd(tv_cmd);
+	return 0;
+}
+
+static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static u16 tcm_vhost_set_fabric_sense_len(struct se_cmd *se_cmd,
+	u32 sense_length)
+{
+	return 0;
+}
+
+static u16 tcm_vhost_get_fabric_sense_len(void)
+{
+	return 0;
+}
+
+static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
+{
+	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
+
+	/* TODO locking against target/backend threads? */
+	transport_generic_free_cmd(se_cmd, 1);
+
+	if (tv_cmd->tvc_sgl_count) {
+		u32 i;
+		for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
+			put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+
+		kfree(tv_cmd->tvc_sgl);
+	}
+
+	kfree(tv_cmd);
+}
+
+/* Dequeue a command from the completion list */
+static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion(
+	struct vhost_scsi *vs)
+{
+	struct tcm_vhost_cmd *tv_cmd = NULL;
+
+	spin_lock_bh(&vs->vs_completion_lock);
+	if (list_empty(&vs->vs_completion_list)) {
+		spin_unlock_bh(&vs->vs_completion_lock);
+		return NULL;
+	}
+
+	list_for_each_entry(tv_cmd, &vs->vs_completion_list,
+			    tvc_completion_list) {
+		list_del(&tv_cmd->tvc_completion_list);
+		break;
+	}
+	spin_unlock_bh(&vs->vs_completion_lock);
+	return tv_cmd;
+}
+
+/* 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);
+	struct tcm_vhost_cmd *tv_cmd;
+
+	while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs)) != NULL) {
+		struct virtio_scsi_cmd_resp v_rsp;
+		struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
+		int ret;
+
+		pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
+			tv_cmd, se_cmd->residual_count, se_cmd->scsi_status);
+
+		memset(&v_rsp, 0, sizeof(v_rsp));
+		v_rsp.resid = se_cmd->residual_count;
+		/* TODO is status_qualifier field needed? */
+		v_rsp.status = se_cmd->scsi_status;
+		v_rsp.sense_len = se_cmd->scsi_sense_length;
+		memcpy(v_rsp.sense, tv_cmd->tvc_sense_buf,
+		       v_rsp.sense_len);
+		ret = copy_to_user(tv_cmd->tvc_resp, &v_rsp, sizeof(v_rsp));
+		if (likely(ret == 0))
+			vhost_add_used(&vs->vqs[2], tv_cmd->tvc_vq_desc, 0);
+		else
+			pr_err("Faulted on virtio_scsi_cmd_resp\n");
+
+		vhost_scsi_free_cmd(tv_cmd);
+	}
+
+	vhost_signal(&vs->dev, &vs->vqs[2]);
+}
+
+static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd)
+{
+	struct vhost_scsi *vs = tv_cmd->tvc_vhost;
+
+	pr_debug("%s tv_cmd %p\n", __func__, tv_cmd);
+
+	spin_lock_bh(&vs->vs_completion_lock);
+	list_add_tail(&tv_cmd->tvc_completion_list,
&vs->vs_completion_list);
+	spin_unlock_bh(&vs->vs_completion_lock);
+
+	vhost_work_queue(&vs->dev, &vs->vs_completion_work);
+}
+
+static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
+	struct tcm_vhost_tpg *tv_tpg,
+	struct virtio_scsi_cmd_req *v_req,
+	u32 exp_data_len,
+	int data_direction)
+{
+	struct tcm_vhost_cmd *tv_cmd;
+	struct tcm_vhost_nexus *tv_nexus;
+	struct se_portal_group *se_tpg = &tv_tpg->se_tpg;
+	struct se_session *se_sess;
+	struct se_cmd *se_cmd;
+	int sam_task_attr;
+
+	tv_nexus = tv_tpg->tpg_nexus;
+	if (!tv_nexus) {
+		pr_err("Unable to locate active struct tcm_vhost_nexus\n");
+		return ERR_PTR(-EIO);
+	}
+	se_sess = tv_nexus->tvn_se_sess;
+
+	tv_cmd = kzalloc(sizeof(struct tcm_vhost_cmd), GFP_ATOMIC);
+	if (!tv_cmd) {
+		pr_err("Unable to allocate struct tcm_vhost_cmd\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	INIT_LIST_HEAD(&tv_cmd->tvc_completion_list);
+	tv_cmd->tvc_tag = v_req->tag;
+
+	se_cmd = &tv_cmd->tvc_se_cmd;
+	/*
+	 * Locate the SAM Task Attr from virtio_scsi_cmd_req
+	 */
+	sam_task_attr = v_req->task_attr;
+	/*
+	 * Initialize struct se_cmd descriptor from TCM infrastructure
+	 */
+	transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, exp_data_len,
+				data_direction, sam_task_attr,
+				&tv_cmd->tvc_sense_buf[0]);
+
+#if 0	/* FIXME: vhost_scsi_allocate_cmd() BIDI operation */
+	if (bidi)
+		se_cmd->se_cmd_flags |= SCF_BIDI;
+#endif
+	return tv_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 scatterlist *sgl,
+	unsigned int sgl_count, void __user *ptr, size_t len, int write)
+{
+	struct scatterlist *sg = sgl;
+	unsigned int npages = 0;
+	int ret;
+
+	while (len > 0) {
+		struct page *page;
+		unsigned int offset = (uintptr_t)ptr & ~PAGE_MASK;
+		unsigned int nbytes = min_t(unsigned int,
+				PAGE_SIZE - offset, len);
+
+		if (npages == sgl_count) {
+			ret = -ENOBUFS;
+			goto err;
+		}
+
+		ret = get_user_pages_fast((unsigned long)ptr, 1, write, &page);
+		BUG_ON(ret == 0); /* we should either get our page or fail */
+		if (ret < 0)
+			goto err;
+
+		sg_set_page(sg, page, nbytes, offset);
+		ptr += nbytes;
+		len -= nbytes;
+		sg++;
+		npages++;
+	}
+	return npages;
+
+err:
+	/* Put pages that we hold */
+	for (sg = sgl; sg != &sgl[npages]; sg++)
+		put_page(sg_page(sg));
+	return ret;
+}
+
+static int vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *tv_cmd,
+	struct iovec *iov, unsigned int niov, int write)
+{
+	int ret;
+	unsigned int i;
+	u32 sgl_count;
+	struct scatterlist *sg;
+
+	/*
+	 * Find out how long sglist needs to be
+	 */
+	sgl_count = 0;
+	for (i = 0; i < niov; i++) {
+		sgl_count += (((uintptr_t)iov[i].iov_base + iov[i].iov_len +
+				PAGE_SIZE - 1) >> PAGE_SHIFT) -
+				((uintptr_t)iov[i].iov_base >> PAGE_SHIFT);
+	}
+	/* TODO overflow checking */
+
+	sg = kmalloc(sizeof(tv_cmd->tvc_sgl[0]) * sgl_count, GFP_ATOMIC);
+	if (!sg)
+		return -ENOMEM;
+	pr_debug("%s sg %p sgl_count %u is_err %ld\n", __func__,
+	       sg, sgl_count, IS_ERR(sg));
+	sg_init_table(sg, sgl_count);
+
+	tv_cmd->tvc_sgl = sg;
+	tv_cmd->tvc_sgl_count = sgl_count;
+
+	pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
+	for (i = 0; i < niov; i++) {
+		ret = vhost_scsi_map_to_sgl(sg, sgl_count, iov[i].iov_base,
+					iov[i].iov_len, write);
+		if (ret < 0) {
+			for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
+				put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+			kfree(tv_cmd->tvc_sgl);
+			tv_cmd->tvc_sgl = NULL;
+			tv_cmd->tvc_sgl_count = 0;
+			return ret;
+		}
+
+		sg += ret;
+		sgl_count -= ret;
+	}
+	return 0;
+}
+
+static void tcm_vhost_submission_work(struct work_struct *work)
+{
+	struct tcm_vhost_cmd *tv_cmd +		container_of(work, struct tcm_vhost_cmd,
work);
+	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
+	struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL;
+	int rc, sg_no_bidi = 0;
+	/*
+	 * Locate the struct se_lun pointer based on v_req->lun, and
+	 * attach it to struct se_cmd
+	 */
+	rc = transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd, tv_cmd->tvc_lun);
+	if (rc < 0) {
+		pr_err("Failed to look up lun: %d\n", tv_cmd->tvc_lun);
+		transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd,
+			tv_cmd->tvc_se_cmd.scsi_sense_reason, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	}
+
+	rc = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb);
+	if (rc == -ENOMEM) {
+		transport_send_check_condition_and_sense(se_cmd,
+				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	} else if (rc < 0) {
+		if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
+			tcm_vhost_queue_status(se_cmd);
+		else
+			transport_send_check_condition_and_sense(se_cmd,
+					se_cmd->scsi_sense_reason, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	}
+
+	if (tv_cmd->tvc_sgl_count) {
+		sg_ptr = tv_cmd->tvc_sgl;
+		/*
+		 * For BIDI commands, pass in the extra READ buffer
+		 * to transport_generic_map_mem_to_cmd() below..
+		 */
+/* FIXME: Fix BIDI operation in tcm_vhost_submission_work() */
+#if 0
+		if (se_cmd->se_cmd_flags & SCF_BIDI) {
+			sg_bidi_ptr = NULL;
+			sg_no_bidi = 0;
+		}
+#endif
+	} else {
+		sg_ptr = NULL;
+	}
+
+	rc = transport_generic_map_mem_to_cmd(se_cmd, sg_ptr,
+				tv_cmd->tvc_sgl_count, sg_bidi_ptr,
+				sg_no_bidi);
+	if (rc < 0) {
+		transport_send_check_condition_and_sense(se_cmd,
+				se_cmd->scsi_sense_reason, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	}
+	transport_handle_cdb_direct(se_cmd);
+}
+
+static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
+{
+	struct vhost_virtqueue *vq = &vs->vqs[2];
+	struct virtio_scsi_cmd_req v_req;
+	struct tcm_vhost_tpg *tv_tpg;
+	struct tcm_vhost_cmd *tv_cmd;
+	u32 exp_data_len, data_first, data_num, data_direction;
+	unsigned out, in, i;
+	int head, ret;
+
+	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
+	tv_tpg = vs->vs_tpg;
+	if (unlikely(!tv_tpg)) {
+		pr_err("%s endpoint not set\n", __func__);
+		return;
+	}
+
+	mutex_lock(&vq->mutex);
+	vhost_disable_notify(&vs->dev, vq);
+
+	for (;;) {
+		head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
+					ARRAY_SIZE(vq->iov), &out, &in,
+					NULL, NULL);
+		pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
+					head, out, in);
+		/* 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(&vs->dev, vq))) {
+				vhost_disable_notify(&vs->dev, vq);
+				continue;
+			}
+			break;
+		}
+
+/* FIXME: BIDI operation */
+		if (out == 1 && in == 1) {
+			data_direction = DMA_NONE;
+			data_first = 0;
+			data_num = 0;
+		} else if (out == 1 && in > 1) {
+			data_direction = DMA_FROM_DEVICE;
+			data_first = out + 1;
+			data_num = in - 1;
+		} else if (out > 1 && in == 1) {
+			data_direction = DMA_TO_DEVICE;
+			data_first = 1;
+			data_num = out - 1;
+		} else {
+			vq_err(vq, "Invalid buffer layout out: %u in: %u\n",
+					out, in);
+			break;
+		}
+
+		/*
+		 * Check for a sane resp buffer so we can report errors to
+		 * the guest.
+		 */
+		if (unlikely(vq->iov[out].iov_len !+					sizeof(struct
virtio_scsi_cmd_resp))) {
+			vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
+				" bytes\n", vq->iov[out].iov_len);
+			break;
+		}
+
+		if (unlikely(vq->iov[0].iov_len != sizeof(v_req))) {
+			vq_err(vq, "Expecting virtio_scsi_cmd_req, got %zu"
+				" bytes\n", vq->iov[0].iov_len);
+			break;
+		}
+		pr_debug("Calling __copy_from_user: vq->iov[0].iov_base: %p,"
+			" len: %zu\n", vq->iov[0].iov_base, sizeof(v_req));
+		ret = __copy_from_user(&v_req, vq->iov[0].iov_base,
+				sizeof(v_req));
+		if (unlikely(ret)) {
+			vq_err(vq, "Faulted on virtio_scsi_cmd_req\n");
+			break;
+		}
+
+		exp_data_len = 0;
+		for (i = 0; i < data_num; i++)
+			exp_data_len += vq->iov[data_first + i].iov_len;
+
+		tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
+					exp_data_len, data_direction);
+		if (IS_ERR(tv_cmd)) {
+			vq_err(vq, "vhost_scsi_allocate_cmd failed %ld\n",
+					PTR_ERR(tv_cmd));
+			break;
+		}
+		pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction"
+			": %d\n", tv_cmd, exp_data_len, data_direction);
+
+		tv_cmd->tvc_vhost = vs;
+
+		if (unlikely(vq->iov[out].iov_len !+				sizeof(struct
virtio_scsi_cmd_resp))) {
+			vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
+				" bytes, out: %d, in: %d\n",
+				vq->iov[out].iov_len, out, in);
+			break;
+		}
+
+		tv_cmd->tvc_resp = vq->iov[out].iov_base;
+
+		/*
+		 * Copy in the recieved CDB descriptor into tv_cmd->tvc_cdb
+		 * that will be used by tcm_vhost_new_cmd_map() and down into
+		 * target_setup_cmd_from_cdb()
+		 */
+		memcpy(tv_cmd->tvc_cdb, v_req.cdb, TCM_VHOST_MAX_CDB_SIZE);
+		/*
+		 * Check that the recieved CDB size does not exceeded our
+		 * hardcoded max for tcm_vhost
+		 */
+		/* TODO what if cdb was too small for varlen cdb header? */
+		if (unlikely(scsi_command_size(tv_cmd->tvc_cdb) >
+					TCM_VHOST_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(tv_cmd->tvc_cdb),
+				TCM_VHOST_MAX_CDB_SIZE);
+			break; /* TODO */
+		}
+		tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
+
+		pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
+			tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun);
+
+		if (data_direction != DMA_NONE) {
+			ret = vhost_scsi_map_iov_to_sgl(tv_cmd,
+					&vq->iov[data_first], data_num,
+					data_direction == DMA_TO_DEVICE);
+			if (unlikely(ret)) {
+				vq_err(vq, "Failed to map iov to sgl\n");
+				break; /* TODO */
+			}
+		}
+
+		/*
+		 * Save the descriptor from vhost_get_vq_desc() to be used to
+		 * complete the virtio-scsi request in TCM callback context via
+		 * tcm_vhost_queue_data_in() and tcm_vhost_queue_status()
+		 */
+		tv_cmd->tvc_vq_desc = head;
+		/*
+		 * Dispatch tv_cmd descriptor for cmwq execution in process
+		 * context provided by tcm_vhost_workqueue.  This also ensures
+		 * tv_cmd is executed on the same kworker CPU as this vhost
+		 * thread to gain positive L2 cache locality effects..
+		 */
+		INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work);
+		queue_work(tcm_vhost_workqueue, &tv_cmd->work);
+	}
+
+	mutex_unlock(&vq->mutex);
+}
+
+static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
+{
+	pr_err("%s: The handling func for control queue.\n", __func__);
+}
+
+static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
+{
+	pr_err("%s: The handling func for event queue.\n", __func__);
+}
+
+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);
+}
+
+/*
+ * Called from vhost_scsi_ioctl() context to walk the list of available
+ * tcm_vhost_tpg with an active struct tcm_vhost_nexus
+ */
+static int vhost_scsi_set_endpoint(
+	struct vhost_scsi *vs,
+	struct vhost_scsi_target *t)
+{
+	struct tcm_vhost_tport *tv_tport;
+	struct tcm_vhost_tpg *tv_tpg;
+	int index;
+
+	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])) {
+			mutex_unlock(&vs->dev.mutex);
+			return -EFAULT;
+		}
+	}
+
+	if (vs->vs_tpg) {
+		mutex_unlock(&vs->dev.mutex);
+		return -EEXIST;
+	}
+	mutex_unlock(&vs->dev.mutex);
+
+	mutex_lock(&tcm_vhost_mutex);
+	list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
+		mutex_lock(&tv_tpg->tv_tpg_mutex);
+		if (!tv_tpg->tpg_nexus) {
+			mutex_unlock(&tv_tpg->tv_tpg_mutex);
+			continue;
+		}
+		if (atomic_read(&tv_tpg->tv_tpg_vhost_count)) {
+			mutex_unlock(&tv_tpg->tv_tpg_mutex);
+			continue;
+		}
+		tv_tport = tv_tpg->tport;
+
+		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn) &&
+		    (tv_tpg->tport_tpgt == t->vhost_tpgt)) {
+			atomic_inc(&tv_tpg->tv_tpg_vhost_count);
+			smp_mb__after_atomic_inc();
+			mutex_unlock(&tv_tpg->tv_tpg_mutex);
+			mutex_unlock(&tcm_vhost_mutex);
+
+			mutex_lock(&vs->dev.mutex);
+			vs->vs_tpg = tv_tpg;
+			atomic_inc(&vs->vhost_ref_cnt);
+			smp_mb__after_atomic_inc();
+			mutex_unlock(&vs->dev.mutex);
+			return 0;
+		}
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+	}
+	mutex_unlock(&tcm_vhost_mutex);
+	return -EINVAL;
+}
+
+static int vhost_scsi_clear_endpoint(
+	struct vhost_scsi *vs,
+	struct vhost_scsi_target *t)
+{
+	struct tcm_vhost_tport *tv_tport;
+	struct tcm_vhost_tpg *tv_tpg;
+	int index;
+
+	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])) {
+			mutex_unlock(&vs->dev.mutex);
+			return -EFAULT;
+		}
+	}
+
+	if (!vs->vs_tpg) {
+		mutex_unlock(&vs->dev.mutex);
+		return -ENODEV;
+	}
+	tv_tpg = vs->vs_tpg;
+	tv_tport = tv_tpg->tport;
+
+	if (strcmp(tv_tport->tport_name, t->vhost_wwpn) ||
+	    (tv_tpg->tport_tpgt != t->vhost_tpgt)) {
+		mutex_unlock(&vs->dev.mutex);
+		pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt: %hu"
+			" does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
+			tv_tport->tport_name, tv_tpg->tport_tpgt,
+			t->vhost_wwpn, t->vhost_tpgt);
+		return -EINVAL;
+	}
+	atomic_dec(&tv_tpg->tv_tpg_vhost_count);
+	vs->vs_tpg = NULL;
+	mutex_unlock(&vs->dev.mutex);
+
+	return 0;
+}
+
+static int vhost_scsi_open(struct inode *inode, struct file *f)
+{
+	struct vhost_scsi *s;
+	int r;
+
+	s = kzalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
+	INIT_LIST_HEAD(&s->vs_completion_list);
+	spin_lock_init(&s->vs_completion_lock);
+
+	s->vqs[0].handle_kick = vhost_scsi_ctl_handle_kick;
+	s->vqs[1].handle_kick = vhost_scsi_evt_handle_kick;
+	s->vqs[2].handle_kick = vhost_scsi_handle_kick;
+	r = vhost_dev_init(&s->dev, s->vqs, 3);
+	if (r < 0) {
+		kfree(s);
+		return r;
+	}
+
+	f->private_data = s;
+	return 0;
+}
+
+static int vhost_scsi_release(struct inode *inode, struct file *f)
+{
+	struct vhost_scsi *s = f->private_data;
+
+	if (s->vs_tpg && s->vs_tpg->tport) {
+		struct vhost_scsi_target backend;
+
+		memcpy(backend.vhost_wwpn, s->vs_tpg->tport->tport_name,
+				sizeof(backend.vhost_wwpn));
+		backend.vhost_tpgt = s->vs_tpg->tport_tpgt;
+		vhost_scsi_clear_endpoint(s, &backend);
+	}
+
+	vhost_dev_cleanup(&s->dev, false);
+	kfree(s);
+	return 0;
+}
+
+static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
+{
+	if (features & ~VHOST_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;
+	}
+	vs->dev.acked_features = features;
+	/* TODO possibly smp_wmb() and flush vqs */
+	mutex_unlock(&vs->dev.mutex);
+	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;
+	u64 features;
+	int r;
+
+	switch (ioctl) {
+	case VHOST_SCSI_SET_ENDPOINT:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+
+		return vhost_scsi_set_endpoint(vs, &backend);
+	case VHOST_SCSI_CLEAR_ENDPOINT:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+
+		return vhost_scsi_clear_endpoint(vs, &backend);
+	case VHOST_SCSI_GET_ABI_VERSION:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+
+		backend.abi_version = VHOST_SCSI_ABI_VERSION;
+
+		if (copy_to_user(argp, &backend, sizeof backend))
+			return -EFAULT;
+		return 0;
+	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;
+		return vhost_scsi_set_features(vs, features);
+	default:
+		mutex_lock(&vs->dev.mutex);
+		r = vhost_dev_ioctl(&vs->dev, ioctl, arg);
+		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,
+	/* TODO compat 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 int vhost_scsi_deregister(void)
+{
+	return misc_deregister(&vhost_scsi_misc);
+}
+
+static char *tcm_vhost_dump_proto_id(struct tcm_vhost_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 int tcm_vhost_port_link(
+	struct se_portal_group *se_tpg,
+	struct se_lun *lun)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+
+	atomic_inc(&tv_tpg->tv_tpg_port_count);
+	smp_mb__after_atomic_inc();
+
+	return 0;
+}
+
+static void tcm_vhost_port_unlink(
+	struct se_portal_group *se_tpg,
+	struct se_lun *se_lun)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+
+	atomic_dec(&tv_tpg->tv_tpg_port_count);
+	smp_mb__after_atomic_dec();
+}
+
+static struct se_node_acl *tcm_vhost_make_nodeacl(
+	struct se_portal_group *se_tpg,
+	struct config_group *group,
+	const char *name)
+{
+	struct se_node_acl *se_nacl, *se_nacl_new;
+	struct tcm_vhost_nacl *nacl;
+	u64 wwpn = 0;
+	u32 nexus_depth;
+
+	/* tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
+		return ERR_PTR(-EINVAL); */
+	se_nacl_new = tcm_vhost_alloc_fabric_acl(se_tpg);
+	if (!se_nacl_new)
+		return ERR_PTR(-ENOMEM);
+
+	nexus_depth = 1;
+	/*
+	 * se_nacl_new may be released by core_tpg_add_initiator_node_acl()
+	 * when converting a NodeACL from demo mode -> explict
+	 */
+	se_nacl = core_tpg_add_initiator_node_acl(se_tpg, se_nacl_new,
+				name, nexus_depth);
+	if (IS_ERR(se_nacl)) {
+		tcm_vhost_release_fabric_acl(se_tpg, se_nacl_new);
+		return se_nacl;
+	}
+	/*
+	 * Locate our struct tcm_vhost_nacl and set the FC Nport WWPN
+	 */
+	nacl = container_of(se_nacl, struct tcm_vhost_nacl, se_node_acl);
+	nacl->iport_wwpn = wwpn;
+
+	return se_nacl;
+}
+
+static void tcm_vhost_drop_nodeacl(struct se_node_acl *se_acl)
+{
+	struct tcm_vhost_nacl *nacl = container_of(se_acl,
+				struct tcm_vhost_nacl, se_node_acl);
+	core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
+	kfree(nacl);
+}
+
+static int tcm_vhost_make_nexus(
+	struct tcm_vhost_tpg *tv_tpg,
+	const char *name)
+{
+	struct se_portal_group *se_tpg;
+	struct tcm_vhost_nexus *tv_nexus;
+
+	mutex_lock(&tv_tpg->tv_tpg_mutex);
+	if (tv_tpg->tpg_nexus) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		pr_debug("tv_tpg->tpg_nexus already exists\n");
+		return -EEXIST;
+	}
+	se_tpg = &tv_tpg->se_tpg;
+
+	tv_nexus = kzalloc(sizeof(struct tcm_vhost_nexus), GFP_KERNEL);
+	if (!tv_nexus) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		pr_err("Unable to allocate struct tcm_vhost_nexus\n");
+		return -ENOMEM;
+	}
+	/*
+	 *  Initialize the struct se_session pointer
+	 */
+	tv_nexus->tvn_se_sess = transport_init_session();
+	if (IS_ERR(tv_nexus->tvn_se_sess)) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		kfree(tv_nexus);
+		return -ENOMEM;
+	}
+	/*
+	 * Since we are running in 'demo mode' this call with generate a
+	 * struct se_node_acl for the tcm_vhost struct se_portal_group with
+	 * the SCSI Initiator port name of the passed configfs group 'name'.
+	 */
+	tv_nexus->tvn_se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
+				se_tpg, (unsigned char *)name);
+	if (!tv_nexus->tvn_se_sess->se_node_acl) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		pr_debug("core_tpg_check_initiator_node_acl() failed"
+				" for %s\n", name);
+		transport_free_session(tv_nexus->tvn_se_sess);
+		kfree(tv_nexus);
+		return -ENOMEM;
+	}
+	/*
+	 * Now register the TCM vHost virtual I_T Nexus as active with the
+	 * call to __transport_register_session()
+	 */
+	__transport_register_session(se_tpg, tv_nexus->tvn_se_sess->se_node_acl,
+			tv_nexus->tvn_se_sess, tv_nexus);
+	tv_tpg->tpg_nexus = tv_nexus;
+
+	mutex_unlock(&tv_tpg->tv_tpg_mutex);
+	return 0;
+}
+
+static int tcm_vhost_drop_nexus(
+	struct tcm_vhost_tpg *tpg)
+{
+	struct se_session *se_sess;
+	struct tcm_vhost_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 (atomic_read(&tpg->tv_tpg_port_count)) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to remove TCM_vHost I_T Nexus with"
+			" active TPG port count: %d\n",
+			atomic_read(&tpg->tv_tpg_port_count));
+		return -EPERM;
+	}
+
+	if (atomic_read(&tpg->tv_tpg_vhost_count)) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to remove TCM_vHost I_T Nexus with"
+			" active TPG vhost count: %d\n",
+			atomic_read(&tpg->tv_tpg_vhost_count));
+		return -EPERM;
+	}
+
+	pr_debug("TCM_vHost_ConfigFS: Removing I_T Nexus to emulated"
+		" %s Initiator Port: %s\n", tcm_vhost_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
+	 */
+	transport_deregister_session(tv_nexus->tvn_se_sess);
+	tpg->tpg_nexus = NULL;
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	kfree(tv_nexus);
+	return 0;
+}
+
+static ssize_t tcm_vhost_tpg_show_nexus(
+	struct se_portal_group *se_tpg,
+	char *page)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_nexus *tv_nexus;
+	ssize_t ret;
+
+	mutex_lock(&tv_tpg->tv_tpg_mutex);
+	tv_nexus = tv_tpg->tpg_nexus;
+	if (!tv_nexus) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+	ret = snprintf(page, PAGE_SIZE, "%s\n",
+			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
+	mutex_unlock(&tv_tpg->tv_tpg_mutex);
+
+	return ret;
+}
+
+static ssize_t tcm_vhost_tpg_store_nexus(
+	struct se_portal_group *se_tpg,
+	const char *page,
+	size_t count)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport_wwn = tv_tpg->tport;
+	unsigned char i_port[TCM_VHOST_NAMELEN], *ptr, *port_ptr;
+	int ret;
+	/*
+	 * Shutdown the active I_T nexus if 'NULL' is passed..
+	 */
+	if (!strncmp(page, "NULL", 4)) {
+		ret = tcm_vhost_drop_nexus(tv_tpg);
+		return (!ret) ? count : ret;
+	}
+	/*
+	 * Otherwise make sure the passed virtual Initiator port WWN matches
+	 * the fabric protocol_id set in tcm_vhost_make_tport(), and call
+	 * tcm_vhost_make_nexus().
+	 */
+	if (strlen(page) >= TCM_VHOST_NAMELEN) {
+		pr_err("Emulated NAA Sas Address: %s, exceeds"
+				" max: %d\n", page, TCM_VHOST_NAMELEN);
+		return -EINVAL;
+	}
+	snprintf(&i_port[0], TCM_VHOST_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,
+				tcm_vhost_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,
+				tcm_vhost_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,
+				tcm_vhost_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 = tcm_vhost_make_nexus(tv_tpg, port_ptr);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+TF_TPG_BASE_ATTR(tcm_vhost, nexus, S_IRUGO | S_IWUSR);
+
+static struct configfs_attribute *tcm_vhost_tpg_attrs[] = {
+	&tcm_vhost_tpg_nexus.attr,
+	NULL,
+};
+
+static struct se_portal_group *tcm_vhost_make_tpg(
+	struct se_wwn *wwn,
+	struct config_group *group,
+	const char *name)
+{
+	struct tcm_vhost_tport *tport = container_of(wwn,
+			struct tcm_vhost_tport, tport_wwn);
+
+	struct tcm_vhost_tpg *tpg;
+	unsigned long tpgt;
+	int ret;
+
+	if (strstr(name, "tpgt_") != name)
+		return ERR_PTR(-EINVAL);
+	if (kstrtoul(name + 5, 10, &tpgt) || tpgt > UINT_MAX)
+		return ERR_PTR(-EINVAL);
+
+	tpg = kzalloc(sizeof(struct tcm_vhost_tpg), GFP_KERNEL);
+	if (!tpg) {
+		pr_err("Unable to allocate struct tcm_vhost_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(&tcm_vhost_fabric_configfs->tf_ops, wwn,
+				&tpg->se_tpg, tpg, TRANSPORT_TPG_TYPE_NORMAL);
+	if (ret < 0) {
+		kfree(tpg);
+		return NULL;
+	}
+	mutex_lock(&tcm_vhost_mutex);
+	list_add_tail(&tpg->tv_tpg_list, &tcm_vhost_list);
+	mutex_unlock(&tcm_vhost_mutex);
+
+	return &tpg->se_tpg;
+}
+
+static void tcm_vhost_drop_tpg(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+
+	mutex_lock(&tcm_vhost_mutex);
+	list_del(&tpg->tv_tpg_list);
+	mutex_unlock(&tcm_vhost_mutex);
+	/*
+	 * Release the virtual I_T Nexus for this vHost TPG
+	 */
+	tcm_vhost_drop_nexus(tpg);
+	/*
+	 * Deregister the se_tpg from TCM..
+	 */
+	core_tpg_deregister(se_tpg);
+	kfree(tpg);
+}
+
+static struct se_wwn *tcm_vhost_make_tport(
+	struct target_fabric_configfs *tf,
+	struct config_group *group,
+	const char *name)
+{
+	struct tcm_vhost_tport *tport;
+	char *ptr;
+	u64 wwpn = 0;
+	int off = 0;
+
+	/* if (tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
+		return ERR_PTR(-EINVAL); */
+
+	tport = kzalloc(sizeof(struct tcm_vhost_tport), GFP_KERNEL);
+	if (!tport) {
+		pr_err("Unable to allocate struct tcm_vhost_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) >= TCM_VHOST_NAMELEN) {
+		pr_err("Emulated %s Address: %s, exceeds"
+			" max: %d\n", name, tcm_vhost_dump_proto_id(tport),
+			TCM_VHOST_NAMELEN);
+		kfree(tport);
+		return ERR_PTR(-EINVAL);
+	}
+	snprintf(&tport->tport_name[0], TCM_VHOST_NAMELEN, "%s",
&name[off]);
+
+	pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
+		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport), name);
+
+	return &tport->tport_wwn;
+}
+
+static void tcm_vhost_drop_tport(struct se_wwn *wwn)
+{
+	struct tcm_vhost_tport *tport = container_of(wwn,
+				struct tcm_vhost_tport, tport_wwn);
+
+	pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
+		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport),
+		tport->tport_name);
+
+	kfree(tport);
+}
+
+static ssize_t tcm_vhost_wwn_show_attr_version(
+	struct target_fabric_configfs *tf,
+	char *page)
+{
+	return sprintf(page, "TCM_VHOST fabric module %s on %s/%s"
+		"on "UTS_RELEASE"\n", TCM_VHOST_VERSION,
utsname()->sysname,
+		utsname()->machine);
+}
+
+TF_WWN_ATTR_RO(tcm_vhost, version);
+
+static struct configfs_attribute *tcm_vhost_wwn_attrs[] = {
+	&tcm_vhost_wwn_version.attr,
+	NULL,
+};
+
+static struct target_core_fabric_ops tcm_vhost_ops = {
+	.get_fabric_name		= tcm_vhost_get_fabric_name,
+	.get_fabric_proto_ident		= tcm_vhost_get_fabric_proto_ident,
+	.tpg_get_wwn			= tcm_vhost_get_fabric_wwn,
+	.tpg_get_tag			= tcm_vhost_get_tag,
+	.tpg_get_default_depth		= tcm_vhost_get_default_depth,
+	.tpg_get_pr_transport_id	= tcm_vhost_get_pr_transport_id,
+	.tpg_get_pr_transport_id_len	= tcm_vhost_get_pr_transport_id_len,
+	.tpg_parse_pr_out_transport_id	= tcm_vhost_parse_pr_out_transport_id,
+	.tpg_check_demo_mode		= tcm_vhost_check_true,
+	.tpg_check_demo_mode_cache	= tcm_vhost_check_true,
+	.tpg_check_demo_mode_write_protect = tcm_vhost_check_false,
+	.tpg_check_prod_mode_write_protect = tcm_vhost_check_false,
+	.tpg_alloc_fabric_acl		= tcm_vhost_alloc_fabric_acl,
+	.tpg_release_fabric_acl		= tcm_vhost_release_fabric_acl,
+	.tpg_get_inst_index		= tcm_vhost_tpg_get_inst_index,
+	.release_cmd			= tcm_vhost_release_cmd,
+	.shutdown_session		= tcm_vhost_shutdown_session,
+	.close_session			= tcm_vhost_close_session,
+	.sess_get_index			= tcm_vhost_sess_get_index,
+	.sess_get_initiator_sid		= NULL,
+	.write_pending			= tcm_vhost_write_pending,
+	.write_pending_status		= tcm_vhost_write_pending_status,
+	.set_default_node_attributes	= tcm_vhost_set_default_node_attrs,
+	.get_task_tag			= tcm_vhost_get_task_tag,
+	.get_cmd_state			= tcm_vhost_get_cmd_state,
+	.queue_data_in			= tcm_vhost_queue_data_in,
+	.queue_status			= tcm_vhost_queue_status,
+	.queue_tm_rsp			= tcm_vhost_queue_tm_rsp,
+	.get_fabric_sense_len		= tcm_vhost_get_fabric_sense_len,
+	.set_fabric_sense_len		= tcm_vhost_set_fabric_sense_len,
+	/*
+	 * Setup callers for generic logic in target_core_fabric_configfs.c
+	 */
+	.fabric_make_wwn		= tcm_vhost_make_tport,
+	.fabric_drop_wwn		= tcm_vhost_drop_tport,
+	.fabric_make_tpg		= tcm_vhost_make_tpg,
+	.fabric_drop_tpg		= tcm_vhost_drop_tpg,
+	.fabric_post_link		= tcm_vhost_port_link,
+	.fabric_pre_unlink		= tcm_vhost_port_unlink,
+	.fabric_make_np			= NULL,
+	.fabric_drop_np			= NULL,
+	.fabric_make_nodeacl		= tcm_vhost_make_nodeacl,
+	.fabric_drop_nodeacl		= tcm_vhost_drop_nodeacl,
+};
+
+static int tcm_vhost_register_configfs(void)
+{
+	struct target_fabric_configfs *fabric;
+	int ret;
+
+	pr_debug("TCM_VHOST fabric module %s on %s/%s"
+		" on "UTS_RELEASE"\n", TCM_VHOST_VERSION,
utsname()->sysname,
+		utsname()->machine);
+	/*
+	 * Register the top level struct config_item_type with TCM core
+	 */
+	fabric = target_fabric_configfs_init(THIS_MODULE, "vhost");
+	if (IS_ERR(fabric)) {
+		pr_err("target_fabric_configfs_init() failed\n");
+		return PTR_ERR(fabric);
+	}
+	/*
+	 * Setup fabric->tf_ops from our local tcm_vhost_ops
+	 */
+	fabric->tf_ops = tcm_vhost_ops;
+	/*
+	 * Setup default attribute lists for various fabric->tf_cit_tmpl
+	 */
+	TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = tcm_vhost_wwn_attrs;
+	TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = tcm_vhost_tpg_attrs;
+	TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_base_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_param_cit.ct_attrs = NULL;
+	/*
+	 * Register the fabric for use within TCM
+	 */
+	ret = target_fabric_configfs_register(fabric);
+	if (ret < 0) {
+		pr_err("target_fabric_configfs_register() failed"
+				" for TCM_VHOST\n");
+		return ret;
+	}
+	/*
+	 * Setup our local pointer to *fabric
+	 */
+	tcm_vhost_fabric_configfs = fabric;
+	pr_debug("TCM_VHOST[0] - Set fabric ->
tcm_vhost_fabric_configfs\n");
+	return 0;
+};
+
+static void tcm_vhost_deregister_configfs(void)
+{
+	if (!tcm_vhost_fabric_configfs)
+		return;
+
+	target_fabric_configfs_deregister(tcm_vhost_fabric_configfs);
+	tcm_vhost_fabric_configfs = NULL;
+	pr_debug("TCM_VHOST[0] - Cleared tcm_vhost_fabric_configfs\n");
+};
+
+static int __init tcm_vhost_init(void)
+{
+	int ret = -ENOMEM;
+
+	tcm_vhost_workqueue = alloc_workqueue("tcm_vhost", 0, 0);
+	if (!tcm_vhost_workqueue)
+		goto out;
+
+	ret = vhost_scsi_register();
+	if (ret < 0)
+		goto out_destroy_workqueue;
+
+	ret = tcm_vhost_register_configfs();
+	if (ret < 0)
+		goto out_vhost_scsi_deregister;
+
+	return 0;
+
+out_vhost_scsi_deregister:
+	vhost_scsi_deregister();
+out_destroy_workqueue:
+	destroy_workqueue(tcm_vhost_workqueue);
+out:
+	return ret;
+};
+
+static void tcm_vhost_exit(void)
+{
+	tcm_vhost_deregister_configfs();
+	vhost_scsi_deregister();
+	destroy_workqueue(tcm_vhost_workqueue);
+};
+
+MODULE_DESCRIPTION("TCM_VHOST series fabric driver");
+MODULE_LICENSE("GPL");
+module_init(tcm_vhost_init);
+module_exit(tcm_vhost_exit);
diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
new file mode 100644
index 0000000..c983ed2
--- /dev/null
+++ b/drivers/vhost/tcm_vhost.h
@@ -0,0 +1,101 @@
+#define TCM_VHOST_VERSION  "v0.1"
+#define TCM_VHOST_NAMELEN 256
+#define TCM_VHOST_MAX_CDB_SIZE 32
+
+struct tcm_vhost_cmd {
+	/* Descriptor from vhost_get_vq_desc() for virt_queue segment */
+	int tvc_vq_desc;
+	/* 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;
+	/* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
+	u32 tvc_lun;
+	/* Pointer to the SGL formatted memory from virtio-scsi */
+	struct scatterlist *tvc_sgl;
+	/* Pointer to response */
+	struct virtio_scsi_cmd_resp __user *tvc_resp;
+	/* Pointer to vhost_scsi for our device */
+	struct vhost_scsi *tvc_vhost;
+	/* The TCM I/O descriptor that is accessed via container_of() */
+	struct se_cmd tvc_se_cmd;
+	/* work item used for cmwq dispatch to tcm_vhost_submission_work() */
+	struct work_struct work;
+	/* Copy of the incoming SCSI command descriptor block (CDB) */
+	unsigned char tvc_cdb[TCM_VHOST_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 list_head tvc_completion_list;
+};
+
+struct tcm_vhost_nexus {
+	/* Pointer to TCM session for I_T Nexus */
+	struct se_session *tvn_se_sess;
+};
+
+struct tcm_vhost_nacl {
+	/* Binary World Wide unique Port Name for Vhost Initiator port */
+	u64 iport_wwpn;
+	/* ASCII formatted WWPN for Sas Initiator port */
+	char iport_name[TCM_VHOST_NAMELEN];
+	/* Returned by tcm_vhost_make_nodeacl() */
+	struct se_node_acl se_node_acl;
+};
+
+struct tcm_vhost_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 */
+	atomic_t tv_tpg_port_count;
+	/* Used for vhost_scsi device reference to tpg_nexus */
+	atomic_t tv_tpg_vhost_count;
+	/* list for tcm_vhost_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 tcm_vhost_nexus *tpg_nexus;
+	/* Pointer back to tcm_vhost_tport */
+	struct tcm_vhost_tport *tport;
+	/* Returned by tcm_vhost_make_tpg() */
+	struct se_portal_group se_tpg;
+};
+
+struct tcm_vhost_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[TCM_VHOST_NAMELEN];
+	/* Returned by tcm_vhost_make_tport() */
+	struct se_wwn tport_wwn;
+};
+
+/*
+ * As per request from MST, keep TCM_VHOST related ioctl defines out of
+ * linux/vhost.h (user-space) for now..
+ */
+
+#include <linux/vhost.h>
+
+/*
+ * Used by QEMU userspace to ensure a consistent vhost-scsi ABI.
+ *
+ * ABI Rev 0: July 2012 version starting point for v3.6-rc merge candidate +
+ *            RFC-v2 vhost-scsi userspace.  Add GET_ABI_VERSION ioctl usage
+ */
+
+#define VHOST_SCSI_ABI_VERSION	0
+
+struct vhost_scsi_target {
+	int abi_version;
+	unsigned char vhost_wwpn[TRANSPORT_IQN_LEN];
+	unsigned short vhost_tpgt;
+};
+
+/* VHOST_SCSI specific defines */
+#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct
vhost_scsi_target)
+#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct
vhost_scsi_target)
+#define VHOST_SCSI_GET_ABI_VERSION _IOW(VHOST_VIRTIO, 0x42, struct
vhost_scsi_target)
-- 
1.7.2.5

On Thu, Jul 26, 2012 at 11:43:20PM +0000, Nicholas A. Bellinger
wrote:
> From: Nicholas Bellinger <nab at linux-iscsi.org>
> 
> Hello KVM + QEMU folks,
> 
> This is -v5 of the in-flight tcm_vhost fabric driver for KVM host
virtualized
> target support using the in-kernel storage stack with for-3.6 code.
> 
> The changes since -v4 have been pretty minimal.  A new GET_ABI_VERSION
ioctl
> has been added as requested by Anthony & Co, and after some back
<-> forth on
> the lists we've decided upon a starting point of
VHOST_SCSI_ABI_VERSION=0,
> and vhost-scsi RFC userspace has been updated accordingly.
> 
> Along with that, a few handfuls of vq related error messages where
converted
> to use vq_err as requested by MST, along with some minor checkpatch fixes.
> 
> So this point everything required to run tcm_vhost from drivers/target +
> drivers/vhost, and virtio-scsi LLD bugfix has been merged into v3.6-rc0
code.
> 
> Please have a look and let us know if there are any last-minute pre-merge
> comments ahead of MST returning from holiday this weekend.
> 
> Thank you!
> 
> --nab
Acked-by: Michael S. Tsirkin <mst at redhat.com>

some comments below but can be fixed in-tree I think.
> Changelog v4 -> v5:
> 
>   Expose ABI version via VHOST_SCSI_GET_ABI_VERSION + use Rev 0 as
>   starting point for v3.6-rc code (Stefan + ALiguori + nab)
>   Convert vhost_scsi_handle_vq() to vq_err() (nab + MST)
>   Minor style fixes from checkpatch (nab)
> 
> Changelog v3 -> v4:
> 
>   Rename vhost_vring_target -> vhost_scsi_target (mst + nab)
>   Use TRANSPORT_IQN_LEN in vhost_scsi_target->vhost_wwpn[] def (nab)
>   Move back to drivers/vhost/, and just use drivers/vhost/Kconfig.tcm (mst)
>   Move TCM_VHOST related ioctl defines from include/linux/vhost.h ->
>   drivers/vhost/tcm_vhost.h as requested by MST (nab)
>   Move Kbuild.tcm include from drivers/staging -> drivers/vhost/, and
>   just use 'if STAGING' around 'source
drivers/vhost/Kbuild.tcm'
> 
> Changelog v2 -> v3:
> 
>   Unlock on error in tcm_vhost_drop_nexus() (DanC)
>   Fix strlen() doesn't count the terminator (DanC)
>   Call kfree() on an error path (DanC)
>   Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
>   Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
>   Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
>   as requested by MST (nab)
> 
> Changelog v1 -> v2:
> 
>   Fix tv_cmd completion -> release SGL memory leak (nab)
>   Fix sparse warnings for static variable usage ((Fengguang Wu)
>   Fix sparse warnings for min() typing + printk format specs (Fengguang Wu)
>   Convert to cmwq submission for I/O dispatch (nab + hch)
> 
> Changelog v0 -> v1:
> 
>   Merge into single source + header file, and move to drivers/vhost/
> 
> Cc: Michael S. Tsirkin <mst at redhat.com>
> Cc: Stefan Hajnoczi <stefanha at linux.vnet.ibm.com>
> Cc: Anthony Liguori <aliguori at us.ibm.com>
> Cc: Zhi Yong Wu <wuzhy at cn.ibm.com>
> Cc: Paolo Bonzini <pbonzini at redhat.com>
> Cc: Christoph Hellwig <hch at lst.de>
> Cc: Hannes Reinecke <hare at suse.de>
> Cc: Jens Axboe <axboe at kernel.dk>
> Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
> ---
>  drivers/vhost/Kconfig     |    3 +
>  drivers/vhost/Kconfig.tcm |    6 +
>  drivers/vhost/Makefile    |    2 +
>  drivers/vhost/tcm_vhost.c | 1628
+++++++++++++++++++++++++++++++++++++++++++++
>  drivers/vhost/tcm_vhost.h |  101 +++
>  5 files changed, 1740 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/vhost/Kconfig.tcm
>  create mode 100644 drivers/vhost/tcm_vhost.c
>  create mode 100644 drivers/vhost/tcm_vhost.h
> 
> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> index e4e2fd1..202bba6 100644
> --- a/drivers/vhost/Kconfig
> +++ b/drivers/vhost/Kconfig
> @@ -9,3 +9,6 @@ config VHOST_NET
>  	  To compile this driver as a module, choose M here: the module will
>  	  be called vhost_net.
>  
> +if STAGING
> +source "drivers/vhost/Kconfig.tcm"
> +endif
> diff --git a/drivers/vhost/Kconfig.tcm b/drivers/vhost/Kconfig.tcm
> new file mode 100644
> index 0000000..a9c6f76
> --- /dev/null
> +++ b/drivers/vhost/Kconfig.tcm
> @@ -0,0 +1,6 @@
> +config TCM_VHOST
> +	tristate "TCM_VHOST fabric module (EXPERIMENTAL)"
> +	depends on TARGET_CORE && EVENTFD && EXPERIMENTAL
&& m
> +	default n
> +	---help---
> +	Say M here to enable the TCM_VHOST fabric module for use with virtio-scsi
guests
> diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
> index 72dd020..a27b053 100644
> --- a/drivers/vhost/Makefile
> +++ b/drivers/vhost/Makefile
> @@ -1,2 +1,4 @@
>  obj-$(CONFIG_VHOST_NET) += vhost_net.o
>  vhost_net-y := vhost.o net.o
> +
> +obj-$(CONFIG_TCM_VHOST) += tcm_vhost.o
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> new file mode 100644
> index 0000000..fb36654
> --- /dev/null
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -0,0 +1,1628 @@
>
+/*******************************************************************************
> + * Vhost kernel TCM fabric driver for virtio SCSI initiators
> + *
> + * (C) Copyright 2010-2012 RisingTide Systems LLC.
> + * (C) Copyright 2010-2012 IBM Corp.
> + *
> + * Licensed to the Linux Foundation under the General Public License (GPL)
version 2.
> + *
> + * Authors: Nicholas A. Bellinger <nab at risingtidesystems.com>
> + *          Stefan Hajnoczi <stefanha at 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/vhost.h>
> +#include <linux/fs.h>
> +#include <linux/miscdevice.h>
> +#include <asm/unaligned.h>
> +#include <scsi/scsi.h>
> +#include <scsi/scsi_tcq.h>
> +#include <target/target_core_base.h>
> +#include <target/target_core_fabric.h>
> +#include <target/target_core_fabric_configfs.h>
> +#include <target/target_core_configfs.h>
> +#include <target/configfs_macros.h>
> +#include <linux/vhost.h>
> +#include <linux/virtio_net.h> /* TODO vhost.h currently depends on
this */
> +#include <linux/virtio_scsi.h>
> +
> +#include "vhost.c"
> +#include "vhost.h"
> +#include "tcm_vhost.h"
> +
> +struct vhost_scsi {
> +	atomic_t vhost_ref_cnt;
> +	struct tcm_vhost_tpg *vs_tpg;
Would b enice to add a note on locking about this field.
> +	struct vhost_dev dev;
> +	struct vhost_virtqueue vqs[3];
> +
> +	struct vhost_work vs_completion_work; /* cmd completion work item */
> +	struct list_head vs_completion_list;  /* cmd completion queue */
> +	spinlock_t vs_completion_lock;        /* protects s_completion_list */
> +};
> +
> +/* Local pointer to allocated TCM configfs fabric module */
> +static struct target_fabric_configfs *tcm_vhost_fabric_configfs;
> +
> +static struct workqueue_struct *tcm_vhost_workqueue;
> +
> +/* Global spinlock to protect tcm_vhost TPG list for vhost IOCTL access */
> +static DEFINE_MUTEX(tcm_vhost_mutex);
> +static LIST_HEAD(tcm_vhost_list);
> +
> +static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
> +{
> +	return 1;
> +}
> +
> +static int tcm_vhost_check_false(struct se_portal_group *se_tpg)
> +{
> +	return 0;
> +}
> +
> +static char *tcm_vhost_get_fabric_name(void)
> +{
> +	return "vhost";
> +}
> +
> +static u8 tcm_vhost_get_fabric_proto_ident(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_get_fabric_proto_ident(se_tpg);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_get_fabric_proto_ident(se_tpg);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_get_fabric_proto_ident(se_tpg);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_get_fabric_proto_ident(se_tpg);
> +}
> +
> +static char *tcm_vhost_get_fabric_wwn(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	return &tport->tport_name[0];
> +}
> +
> +static u16 tcm_vhost_get_tag(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	return tpg->tport_tpgt;
> +}
> +
> +static u32 tcm_vhost_get_default_depth(struct se_portal_group *se_tpg)
> +{
> +	return 1;
> +}
> +
> +static u32 tcm_vhost_get_pr_transport_id(
> +	struct se_portal_group *se_tpg,
> +	struct se_node_acl *se_nacl,
> +	struct t10_pr_registration *pr_reg,
> +	int *format_code,
> +	unsigned char *buf)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +					format_code, buf);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +					format_code, buf);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +					format_code, buf);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +			format_code, buf);
> +}
> +
> +static u32 tcm_vhost_get_pr_transport_id_len(
> +	struct se_portal_group *se_tpg,
> +	struct se_node_acl *se_nacl,
> +	struct t10_pr_registration *pr_reg,
> +	int *format_code)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +					format_code);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +					format_code);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +					format_code);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +			format_code);
> +}
> +
> +static char *tcm_vhost_parse_pr_out_transport_id(
> +	struct se_portal_group *se_tpg,
> +	const char *buf,
> +	u32 *out_tid_len,
> +	char **port_nexus_ptr)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +					port_nexus_ptr);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +					port_nexus_ptr);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +					port_nexus_ptr);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +			port_nexus_ptr);
> +}
> +
> +static struct se_node_acl *tcm_vhost_alloc_fabric_acl(
> +	struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_nacl *nacl;
> +
> +	nacl = kzalloc(sizeof(struct tcm_vhost_nacl), GFP_KERNEL);
> +	if (!nacl) {
> +		pr_err("Unable to alocate struct tcm_vhost_nacl\n");
> +		return NULL;
> +	}
> +
> +	return &nacl->se_node_acl;
> +}
> +
> +static void tcm_vhost_release_fabric_acl(
> +	struct se_portal_group *se_tpg,
> +	struct se_node_acl *se_nacl)
> +{
> +	struct tcm_vhost_nacl *nacl = container_of(se_nacl,
> +			struct tcm_vhost_nacl, se_node_acl);
> +	kfree(nacl);
> +}
> +
> +static u32 tcm_vhost_tpg_get_inst_index(struct se_portal_group *se_tpg)
> +{
> +	return 1;
> +}
> +
> +static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
> +{
> +	return;
> +}
> +
> +static int tcm_vhost_shutdown_session(struct se_session *se_sess)
> +{
> +	return 0;
> +}
> +
> +static void tcm_vhost_close_session(struct se_session *se_sess)
> +{
> +	return;
> +}
> +
> +static u32 tcm_vhost_sess_get_index(struct se_session *se_sess)
> +{
> +	return 0;
> +}
> +
> +static int tcm_vhost_write_pending(struct se_cmd *se_cmd)
> +{
> +	/* Go ahead and process the write immediately */
> +	target_execute_cmd(se_cmd);
> +	return 0;
> +}
> +
> +static int tcm_vhost_write_pending_status(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static void tcm_vhost_set_default_node_attrs(struct se_node_acl *nacl)
> +{
> +	return;
> +}
> +
> +static u32 tcm_vhost_get_task_tag(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static int tcm_vhost_get_cmd_state(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *);
can we reorder code to avoid forward declarations?
> +
> +static int tcm_vhost_queue_data_in(struct se_cmd *se_cmd)
> +{
> +	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
> +				struct tcm_vhost_cmd, tvc_se_cmd);
> +	vhost_scsi_complete_cmd(tv_cmd);
> +	return 0;
> +}
> +
> +static int tcm_vhost_queue_status(struct se_cmd *se_cmd)
> +{
> +	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
> +				struct tcm_vhost_cmd, tvc_se_cmd);
> +	vhost_scsi_complete_cmd(tv_cmd);
> +	return 0;
> +}
> +
> +static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static u16 tcm_vhost_set_fabric_sense_len(struct se_cmd *se_cmd,
> +	u32 sense_length)
> +{
> +	return 0;
> +}
> +
> +static u16 tcm_vhost_get_fabric_sense_len(void)
> +{
> +	return 0;
> +}
> +
> +static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> +{
> +	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> +
> +	/* TODO locking against target/backend threads? */
> +	transport_generic_free_cmd(se_cmd, 1);
> +
> +	if (tv_cmd->tvc_sgl_count) {
> +		u32 i;
> +		for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
> +			put_page(sg_page(&tv_cmd->tvc_sgl[i]));
> +
> +		kfree(tv_cmd->tvc_sgl);
> +	}
> +
> +	kfree(tv_cmd);
> +}
> +
> +/* Dequeue a command from the completion list */
> +static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion(
> +	struct vhost_scsi *vs)
> +{
> +	struct tcm_vhost_cmd *tv_cmd = NULL;
> +
> +	spin_lock_bh(&vs->vs_completion_lock);
> +	if (list_empty(&vs->vs_completion_list)) {
> +		spin_unlock_bh(&vs->vs_completion_lock);
> +		return NULL;
> +	}
> +
> +	list_for_each_entry(tv_cmd, &vs->vs_completion_list,
> +			    tvc_completion_list) {
> +		list_del(&tv_cmd->tvc_completion_list);
> +		break;
> +	}
> +	spin_unlock_bh(&vs->vs_completion_lock);
> +	return tv_cmd;
> +}
> +
> +/* 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);
> +	struct tcm_vhost_cmd *tv_cmd;
> +
> +	while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs)) != NULL) {
I normally prefer while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs)))
without != NULL
> +		struct virtio_scsi_cmd_resp v_rsp;
> +		struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> +		int ret;
> +
> +		pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
> +			tv_cmd, se_cmd->residual_count, se_cmd->scsi_status);
> +
> +		memset(&v_rsp, 0, sizeof(v_rsp));
> +		v_rsp.resid = se_cmd->residual_count;
> +		/* TODO is status_qualifier field needed? */
> +		v_rsp.status = se_cmd->scsi_status;
> +		v_rsp.sense_len = se_cmd->scsi_sense_length;
> +		memcpy(v_rsp.sense, tv_cmd->tvc_sense_buf,
> +		       v_rsp.sense_len);
> +		ret = copy_to_user(tv_cmd->tvc_resp, &v_rsp, sizeof(v_rsp));
> +		if (likely(ret == 0))
> +			vhost_add_used(&vs->vqs[2], tv_cmd->tvc_vq_desc, 0);
> +		else
> +			pr_err("Faulted on virtio_scsi_cmd_resp\n");
> +
> +		vhost_scsi_free_cmd(tv_cmd);
> +	}
> +
> +	vhost_signal(&vs->dev, &vs->vqs[2]);
> +}
> +
> +static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd)
> +{
> +	struct vhost_scsi *vs = tv_cmd->tvc_vhost;
> +
> +	pr_debug("%s tv_cmd %p\n", __func__, tv_cmd);
Is this doing something you can not already do with
tracing? If all these pr_debug messages are useful,
I think it's best to add a kconfig entry for them
so that they are off for people even if they build
debug kernels.
> +
> +	spin_lock_bh(&vs->vs_completion_lock);
> +	list_add_tail(&tv_cmd->tvc_completion_list,
&vs->vs_completion_list);
> +	spin_unlock_bh(&vs->vs_completion_lock);
> +
> +	vhost_work_queue(&vs->dev, &vs->vs_completion_work);
> +}
> +
> +static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
> +	struct tcm_vhost_tpg *tv_tpg,
> +	struct virtio_scsi_cmd_req *v_req,
> +	u32 exp_data_len,
> +	int data_direction)
> +{
> +	struct tcm_vhost_cmd *tv_cmd;
> +	struct tcm_vhost_nexus *tv_nexus;
> +	struct se_portal_group *se_tpg = &tv_tpg->se_tpg;
> +	struct se_session *se_sess;
> +	struct se_cmd *se_cmd;
> +	int sam_task_attr;
> +
> +	tv_nexus = tv_tpg->tpg_nexus;
> +	if (!tv_nexus) {
> +		pr_err("Unable to locate active struct tcm_vhost_nexus\n");
> +		return ERR_PTR(-EIO);
> +	}
> +	se_sess = tv_nexus->tvn_se_sess;
> +
> +	tv_cmd = kzalloc(sizeof(struct tcm_vhost_cmd), GFP_ATOMIC);
> +	if (!tv_cmd) {
> +		pr_err("Unable to allocate struct tcm_vhost_cmd\n");
> +		return ERR_PTR(-ENOMEM);
> +	}
> +	INIT_LIST_HEAD(&tv_cmd->tvc_completion_list);
> +	tv_cmd->tvc_tag = v_req->tag;
> +
> +	se_cmd = &tv_cmd->tvc_se_cmd;
> +	/*
> +	 * Locate the SAM Task Attr from virtio_scsi_cmd_req
> +	 */
> +	sam_task_attr = v_req->task_attr;
> +	/*
> +	 * Initialize struct se_cmd descriptor from TCM infrastructure
> +	 */
> +	transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
exp_data_len,
> +				data_direction, sam_task_attr,
> +				&tv_cmd->tvc_sense_buf[0]);
> +
> +#if 0	/* FIXME: vhost_scsi_allocate_cmd() BIDI operation */
> +	if (bidi)
> +		se_cmd->se_cmd_flags |= SCF_BIDI;
> +#endif
> +	return tv_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 scatterlist *sgl,
> +	unsigned int sgl_count, void __user *ptr, size_t len, int write)
> +{
> +	struct scatterlist *sg = sgl;
> +	unsigned int npages = 0;
> +	int ret;
> +
> +	while (len > 0) {
> +		struct page *page;
> +		unsigned int offset = (uintptr_t)ptr & ~PAGE_MASK;
> +		unsigned int nbytes = min_t(unsigned int,
> +				PAGE_SIZE - offset, len);
> +
> +		if (npages == sgl_count) {
> +			ret = -ENOBUFS;
> +			goto err;
> +		}
> +
> +		ret = get_user_pages_fast((unsigned long)ptr, 1, write, &page);
> +		BUG_ON(ret == 0); /* we should either get our page or fail */
> +		if (ret < 0)
> +			goto err;
> +
> +		sg_set_page(sg, page, nbytes, offset);
> +		ptr += nbytes;
> +		len -= nbytes;
> +		sg++;
> +		npages++;
> +	}
> +	return npages;
> +
> +err:
> +	/* Put pages that we hold */
> +	for (sg = sgl; sg != &sgl[npages]; sg++)
> +		put_page(sg_page(sg));
> +	return ret;
> +}
> +
> +static int vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *tv_cmd,
> +	struct iovec *iov, unsigned int niov, int write)
> +{
> +	int ret;
> +	unsigned int i;
> +	u32 sgl_count;
> +	struct scatterlist *sg;
> +
> +	/*
> +	 * Find out how long sglist needs to be
> +	 */
> +	sgl_count = 0;
> +	for (i = 0; i < niov; i++) {
> +		sgl_count += (((uintptr_t)iov[i].iov_base + iov[i].iov_len +
> +				PAGE_SIZE - 1) >> PAGE_SHIFT) -
> +				((uintptr_t)iov[i].iov_base >> PAGE_SHIFT);
> +	}
> +	/* TODO overflow checking */
> +
> +	sg = kmalloc(sizeof(tv_cmd->tvc_sgl[0]) * sgl_count, GFP_ATOMIC);
> +	if (!sg)
> +		return -ENOMEM;
> +	pr_debug("%s sg %p sgl_count %u is_err %ld\n", __func__,
> +	       sg, sgl_count, IS_ERR(sg));
> +	sg_init_table(sg, sgl_count);
> +
> +	tv_cmd->tvc_sgl = sg;
> +	tv_cmd->tvc_sgl_count = sgl_count;
> +
> +	pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
> +	for (i = 0; i < niov; i++) {
> +		ret = vhost_scsi_map_to_sgl(sg, sgl_count, iov[i].iov_base,
> +					iov[i].iov_len, write);
> +		if (ret < 0) {
> +			for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
> +				put_page(sg_page(&tv_cmd->tvc_sgl[i]));
> +			kfree(tv_cmd->tvc_sgl);
> +			tv_cmd->tvc_sgl = NULL;
> +			tv_cmd->tvc_sgl_count = 0;
> +			return ret;
> +		}
> +
> +		sg += ret;
> +		sgl_count -= ret;
> +	}
> +	return 0;
> +}
> +
> +static void tcm_vhost_submission_work(struct work_struct *work)
> +{
> +	struct tcm_vhost_cmd *tv_cmd > +		container_of(work, struct
tcm_vhost_cmd, work);
> +	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> +	struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL;
> +	int rc, sg_no_bidi = 0;
> +	/*
> +	 * Locate the struct se_lun pointer based on v_req->lun, and
> +	 * attach it to struct se_cmd
> +	 */
> +	rc = transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd,
tv_cmd->tvc_lun);
> +	if (rc < 0) {
> +		pr_err("Failed to look up lun: %d\n", tv_cmd->tvc_lun);
> +		transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd,
> +			tv_cmd->tvc_se_cmd.scsi_sense_reason, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	}
> +
> +	rc = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb);
> +	if (rc == -ENOMEM) {
> +		transport_send_check_condition_and_sense(se_cmd,
> +				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	} else if (rc < 0) {
> +		if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
> +			tcm_vhost_queue_status(se_cmd);
> +		else
> +			transport_send_check_condition_and_sense(se_cmd,
> +					se_cmd->scsi_sense_reason, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	}
> +
> +	if (tv_cmd->tvc_sgl_count) {
> +		sg_ptr = tv_cmd->tvc_sgl;
> +		/*
> +		 * For BIDI commands, pass in the extra READ buffer
> +		 * to transport_generic_map_mem_to_cmd() below..
> +		 */
> +/* FIXME: Fix BIDI operation in tcm_vhost_submission_work() */
> +#if 0
> +		if (se_cmd->se_cmd_flags & SCF_BIDI) {
> +			sg_bidi_ptr = NULL;
> +			sg_no_bidi = 0;
> +		}
> +#endif
> +	} else {
> +		sg_ptr = NULL;
> +	}
> +
> +	rc = transport_generic_map_mem_to_cmd(se_cmd, sg_ptr,
> +				tv_cmd->tvc_sgl_count, sg_bidi_ptr,
> +				sg_no_bidi);
> +	if (rc < 0) {
> +		transport_send_check_condition_and_sense(se_cmd,
> +				se_cmd->scsi_sense_reason, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	}
> +	transport_handle_cdb_direct(se_cmd);
> +}
> +
> +static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
> +{
> +	struct vhost_virtqueue *vq = &vs->vqs[2];
> +	struct virtio_scsi_cmd_req v_req;
> +	struct tcm_vhost_tpg *tv_tpg;
> +	struct tcm_vhost_cmd *tv_cmd;
> +	u32 exp_data_len, data_first, data_num, data_direction;
> +	unsigned out, in, i;
> +	int head, ret;
> +
> +	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
> +	tv_tpg = vs->vs_tpg;
> +	if (unlikely(!tv_tpg)) {
> +		pr_err("%s endpoint not set\n", __func__);
> +		return;
> +	}
> +
> +	mutex_lock(&vq->mutex);
> +	vhost_disable_notify(&vs->dev, vq);
> +
> +	for (;;) {
> +		head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
> +					ARRAY_SIZE(vq->iov), &out, &in,
> +					NULL, NULL);
> +		pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
> +					head, out, in);
> +		/* 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(&vs->dev, vq))) {
> +				vhost_disable_notify(&vs->dev, vq);
> +				continue;
> +			}
> +			break;
> +		}
> +
> +/* FIXME: BIDI operation */
> +		if (out == 1 && in == 1) {
> +			data_direction = DMA_NONE;
> +			data_first = 0;
> +			data_num = 0;
> +		} else if (out == 1 && in > 1) {
> +			data_direction = DMA_FROM_DEVICE;
> +			data_first = out + 1;
> +			data_num = in - 1;
> +		} else if (out > 1 && in == 1) {
> +			data_direction = DMA_TO_DEVICE;
> +			data_first = 1;
> +			data_num = out - 1;
> +		} else {
> +			vq_err(vq, "Invalid buffer layout out: %u in: %u\n",
> +					out, in);
> +			break;
> +		}
> +
> +		/*
> +		 * Check for a sane resp buffer so we can report errors to
> +		 * the guest.
> +		 */
> +		if (unlikely(vq->iov[out].iov_len !> +					sizeof(struct
virtio_scsi_cmd_resp))) {
> +			vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
> +				" bytes\n", vq->iov[out].iov_len);
> +			break;
> +		}
> +
> +		if (unlikely(vq->iov[0].iov_len != sizeof(v_req))) {
> +			vq_err(vq, "Expecting virtio_scsi_cmd_req, got %zu"
> +				" bytes\n", vq->iov[0].iov_len);
> +			break;
> +		}
> +		pr_debug("Calling __copy_from_user: vq->iov[0].iov_base:
%p,"
> +			" len: %zu\n", vq->iov[0].iov_base, sizeof(v_req));
> +		ret = __copy_from_user(&v_req, vq->iov[0].iov_base,
> +				sizeof(v_req));
> +		if (unlikely(ret)) {
> +			vq_err(vq, "Faulted on virtio_scsi_cmd_req\n");
> +			break;
> +		}
> +
> +		exp_data_len = 0;
> +		for (i = 0; i < data_num; i++)
> +			exp_data_len += vq->iov[data_first + i].iov_len;
> +
> +		tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
> +					exp_data_len, data_direction);
> +		if (IS_ERR(tv_cmd)) {
> +			vq_err(vq, "vhost_scsi_allocate_cmd failed %ld\n",
> +					PTR_ERR(tv_cmd));
> +			break;
> +		}
> +		pr_debug("Allocated tv_cmd: %p exp_data_len: %d,
data_direction"
> +			": %d\n", tv_cmd, exp_data_len, data_direction);
> +
> +		tv_cmd->tvc_vhost = vs;
> +
> +		if (unlikely(vq->iov[out].iov_len !> +				sizeof(struct
virtio_scsi_cmd_resp))) {
> +			vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
> +				" bytes, out: %d, in: %d\n",
> +				vq->iov[out].iov_len, out, in);
> +			break;
> +		}
> +
> +		tv_cmd->tvc_resp = vq->iov[out].iov_base;
> +
> +		/*
> +		 * Copy in the recieved CDB descriptor into tv_cmd->tvc_cdb
> +		 * that will be used by tcm_vhost_new_cmd_map() and down into
> +		 * target_setup_cmd_from_cdb()
> +		 */
> +		memcpy(tv_cmd->tvc_cdb, v_req.cdb, TCM_VHOST_MAX_CDB_SIZE);
> +		/*
> +		 * Check that the recieved CDB size does not exceeded our
> +		 * hardcoded max for tcm_vhost
> +		 */
> +		/* TODO what if cdb was too small for varlen cdb header? */
> +		if (unlikely(scsi_command_size(tv_cmd->tvc_cdb) >
> +					TCM_VHOST_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(tv_cmd->tvc_cdb),
> +				TCM_VHOST_MAX_CDB_SIZE);
> +			break; /* TODO */
> +		}
> +		tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) &
0x3FFF;
> +
> +		pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
> +			tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun);
> +
> +		if (data_direction != DMA_NONE) {
> +			ret = vhost_scsi_map_iov_to_sgl(tv_cmd,
> +					&vq->iov[data_first], data_num,
> +					data_direction == DMA_TO_DEVICE);
> +			if (unlikely(ret)) {
> +				vq_err(vq, "Failed to map iov to sgl\n");
> +				break; /* TODO */
> +			}
> +		}
> +
> +		/*
> +		 * Save the descriptor from vhost_get_vq_desc() to be used to
> +		 * complete the virtio-scsi request in TCM callback context via
> +		 * tcm_vhost_queue_data_in() and tcm_vhost_queue_status()
> +		 */
> +		tv_cmd->tvc_vq_desc = head;
> +		/*
> +		 * Dispatch tv_cmd descriptor for cmwq execution in process
> +		 * context provided by tcm_vhost_workqueue.  This also ensures
> +		 * tv_cmd is executed on the same kworker CPU as this vhost
> +		 * thread to gain positive L2 cache locality effects..
> +		 */
> +		INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work);
> +		queue_work(tcm_vhost_workqueue, &tv_cmd->work);
> +	}
> +
> +	mutex_unlock(&vq->mutex);
> +}
> +
> +static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
> +{
> +	pr_err("%s: The handling func for control queue.\n", __func__);
> +}
> +
> +static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
> +{
> +	pr_err("%s: The handling func for event queue.\n", __func__);
> +}
> +
can userspace still trigger these? If not pls add a comment explaining
why are above never triggering.
> +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);
> +}
> +
> +/*
> + * Called from vhost_scsi_ioctl() context to walk the list of available
> + * tcm_vhost_tpg with an active struct tcm_vhost_nexus
> + */
> +static int vhost_scsi_set_endpoint(
> +	struct vhost_scsi *vs,
> +	struct vhost_scsi_target *t)
> +{
> +	struct tcm_vhost_tport *tv_tport;
> +	struct tcm_vhost_tpg *tv_tpg;
> +	int index;
> +
> +	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])) {
> +			mutex_unlock(&vs->dev.mutex);
> +			return -EFAULT;
> +		}
> +	}
> +
> +	if (vs->vs_tpg) {
> +		mutex_unlock(&vs->dev.mutex);
> +		return -EEXIST;
> +	}
> +	mutex_unlock(&vs->dev.mutex);
vs->vs_tpg can change at this point and be != NULL in loop below. Not an
issue?
> +	mutex_lock(&tcm_vhost_mutex);
> +	list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
If you move this loop to a function, then it can use goto to cleanup on error.
> +		mutex_lock(&tv_tpg->tv_tpg_mutex);
> +		if (!tv_tpg->tpg_nexus) {
> +			mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +			continue;
> +		}
> +		if (atomic_read(&tv_tpg->tv_tpg_vhost_count)) {
> +			mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +			continue;
> +		}
> +		tv_tport = tv_tpg->tport;
> +
> +		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn) &&
> +		    (tv_tpg->tport_tpgt == t->vhost_tpgt)) {
> +			atomic_inc(&tv_tpg->tv_tpg_vhost_count);
> +			smp_mb__after_atomic_inc();
this an other uses of memory barriers need a comment: what are we
flushing out and why.  Also - could something like kref be used for
reference counting? If this is not datapath this might be better.
> +			mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +			mutex_unlock(&tcm_vhost_mutex);
> +
> +			mutex_lock(&vs->dev.mutex);
> +			vs->vs_tpg = tv_tpg;
> +			atomic_inc(&vs->vhost_ref_cnt);
> +			smp_mb__after_atomic_inc();
> +			mutex_unlock(&vs->dev.mutex);
> +			return 0;
> +		}
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +	}
> +	mutex_unlock(&tcm_vhost_mutex);
> +	return -EINVAL;
> +}
> +
> +static int vhost_scsi_clear_endpoint(
> +	struct vhost_scsi *vs,
> +	struct vhost_scsi_target *t)
> +{
> +	struct tcm_vhost_tport *tv_tport;
> +	struct tcm_vhost_tpg *tv_tpg;
> +	int index;
> +
> +	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])) {
> +			mutex_unlock(&vs->dev.mutex);
> +			return -EFAULT;
> +		}
> +	}
> +
> +	if (!vs->vs_tpg) {
> +		mutex_unlock(&vs->dev.mutex);
> +		return -ENODEV;
> +	}
> +	tv_tpg = vs->vs_tpg;
> +	tv_tport = tv_tpg->tport;
> +
> +	if (strcmp(tv_tport->tport_name, t->vhost_wwpn) ||
> +	    (tv_tpg->tport_tpgt != t->vhost_tpgt)) {
> +		mutex_unlock(&vs->dev.mutex);
> +		pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt:
%hu"
> +			" does not match t->vhost_wwpn: %s, t->vhost_tpgt:
%hu\n",
> +			tv_tport->tport_name, tv_tpg->tport_tpgt,
> +			t->vhost_wwpn, t->vhost_tpgt);
> +		return -EINVAL;
> +	}
> +	atomic_dec(&tv_tpg->tv_tpg_vhost_count);
> +	vs->vs_tpg = NULL;
> +	mutex_unlock(&vs->dev.mutex);
> +
> +	return 0;
We could do it like this:

	err:
		mutex_unlock(&vs->dev.mutex);
		return ret;

to make it clear we do not exit this with lock taken
> +}
> +
> +static int vhost_scsi_open(struct inode *inode, struct file *f)
> +{
> +	struct vhost_scsi *s;
> +	int r;
> +
> +	s = kzalloc(sizeof(*s), GFP_KERNEL);
> +	if (!s)
> +		return -ENOMEM;
> +
> +	vhost_work_init(&s->vs_completion_work,
vhost_scsi_complete_cmd_work);
> +	INIT_LIST_HEAD(&s->vs_completion_list);
> +	spin_lock_init(&s->vs_completion_lock);
> +
> +	s->vqs[0].handle_kick = vhost_scsi_ctl_handle_kick;
> +	s->vqs[1].handle_kick = vhost_scsi_evt_handle_kick;
> +	s->vqs[2].handle_kick = vhost_scsi_handle_kick;
better to add an enum with VQ numbers.
> +	r = vhost_dev_init(&s->dev, s->vqs, 3);
> +	if (r < 0) {
> +		kfree(s);
> +		return r;
> +	}
> +
> +	f->private_data = s;
> +	return 0;
> +}
> +
> +static int vhost_scsi_release(struct inode *inode, struct file *f)
> +{
> +	struct vhost_scsi *s = f->private_data;
> +
> +	if (s->vs_tpg && s->vs_tpg->tport) {
> +		struct vhost_scsi_target backend;
> +
> +		memcpy(backend.vhost_wwpn, s->vs_tpg->tport->tport_name,
> +				sizeof(backend.vhost_wwpn));
> +		backend.vhost_tpgt = s->vs_tpg->tport_tpgt;
> +		vhost_scsi_clear_endpoint(s, &backend);
> +	}
> +
> +	vhost_dev_cleanup(&s->dev, false);
> +	kfree(s);
> +	return 0;
> +}
> +
> +static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> +{
> +	if (features & ~VHOST_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;
> +	}
> +	vs->dev.acked_features = features;
> +	/* TODO possibly smp_wmb() and flush vqs */
Either that or fail if already running.
Current userspace does not change features once set,
but it's cleaner not to make assumptions.
> +	mutex_unlock(&vs->dev.mutex);
> +	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;
> +	u64 features;
> +	int r;
> +
> +	switch (ioctl) {
> +	case VHOST_SCSI_SET_ENDPOINT:
> +		if (copy_from_user(&backend, argp, sizeof backend))
> +			return -EFAULT;
> +
> +		return vhost_scsi_set_endpoint(vs, &backend);
> +	case VHOST_SCSI_CLEAR_ENDPOINT:
> +		if (copy_from_user(&backend, argp, sizeof backend))
> +			return -EFAULT;
> +
> +		return vhost_scsi_clear_endpoint(vs, &backend);
> +	case VHOST_SCSI_GET_ABI_VERSION:
> +		if (copy_from_user(&backend, argp, sizeof backend))
> +			return -EFAULT;
Why are we reading this in BTW?
> +
> +		backend.abi_version = VHOST_SCSI_ABI_VERSION;
> +
> +		if (copy_to_user(argp, &backend, sizeof backend))
> +			return -EFAULT;
> +		return 0;
> +	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;
> +		return vhost_scsi_set_features(vs, features);
> +	default:
> +		mutex_lock(&vs->dev.mutex);
> +		r = vhost_dev_ioctl(&vs->dev, ioctl, arg);
> +		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,
> +	/* TODO compat ioctl? */
well?
> +	.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 int vhost_scsi_deregister(void)
> +{
> +	return misc_deregister(&vhost_scsi_misc);
> +}
> +
> +static char *tcm_vhost_dump_proto_id(struct tcm_vhost_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 int tcm_vhost_port_link(
> +	struct se_portal_group *se_tpg,
> +	struct se_lun *lun)
I'd like this and other places to be like this:
 static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
 	struct se_lun *lun)

or
 static int
 tcm_vhost_port_link(struct se_portal_group *se_tpg,
		     struct se_lun *lun)

so that it's more like the rest of vhost code.

> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +
> +	atomic_inc(&tv_tpg->tv_tpg_port_count);
> +	smp_mb__after_atomic_inc();
> +
> +	return 0;
> +}
> +
> +static void tcm_vhost_port_unlink(
> +	struct se_portal_group *se_tpg,
> +	struct se_lun *se_lun)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +
> +	atomic_dec(&tv_tpg->tv_tpg_port_count);
> +	smp_mb__after_atomic_dec();
> +}
> +
> +static struct se_node_acl *tcm_vhost_make_nodeacl(
> +	struct se_portal_group *se_tpg,
> +	struct config_group *group,
> +	const char *name)
> +{
> +	struct se_node_acl *se_nacl, *se_nacl_new;
> +	struct tcm_vhost_nacl *nacl;
> +	u64 wwpn = 0;
> +	u32 nexus_depth;
> +
> +	/* tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
> +		return ERR_PTR(-EINVAL); */
> +	se_nacl_new = tcm_vhost_alloc_fabric_acl(se_tpg);
> +	if (!se_nacl_new)
> +		return ERR_PTR(-ENOMEM);
> +
> +	nexus_depth = 1;
> +	/*
> +	 * se_nacl_new may be released by core_tpg_add_initiator_node_acl()
> +	 * when converting a NodeACL from demo mode -> explict
> +	 */
> +	se_nacl = core_tpg_add_initiator_node_acl(se_tpg, se_nacl_new,
> +				name, nexus_depth);
> +	if (IS_ERR(se_nacl)) {
> +		tcm_vhost_release_fabric_acl(se_tpg, se_nacl_new);
> +		return se_nacl;
> +	}
> +	/*
> +	 * Locate our struct tcm_vhost_nacl and set the FC Nport WWPN
> +	 */
> +	nacl = container_of(se_nacl, struct tcm_vhost_nacl, se_node_acl);
> +	nacl->iport_wwpn = wwpn;
> +
> +	return se_nacl;
> +}
> +
> +static void tcm_vhost_drop_nodeacl(struct se_node_acl *se_acl)
> +{
> +	struct tcm_vhost_nacl *nacl = container_of(se_acl,
> +				struct tcm_vhost_nacl, se_node_acl);
> +	core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
> +	kfree(nacl);
> +}
> +
> +static int tcm_vhost_make_nexus(
> +	struct tcm_vhost_tpg *tv_tpg,
> +	const char *name)
> +{
> +	struct se_portal_group *se_tpg;
> +	struct tcm_vhost_nexus *tv_nexus;
> +
> +	mutex_lock(&tv_tpg->tv_tpg_mutex);
> +	if (tv_tpg->tpg_nexus) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		pr_debug("tv_tpg->tpg_nexus already exists\n");
> +		return -EEXIST;
> +	}
> +	se_tpg = &tv_tpg->se_tpg;
> +
> +	tv_nexus = kzalloc(sizeof(struct tcm_vhost_nexus), GFP_KERNEL);
> +	if (!tv_nexus) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		pr_err("Unable to allocate struct tcm_vhost_nexus\n");
> +		return -ENOMEM;
> +	}
> +	/*
> +	 *  Initialize the struct se_session pointer
> +	 */
> +	tv_nexus->tvn_se_sess = transport_init_session();
> +	if (IS_ERR(tv_nexus->tvn_se_sess)) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		kfree(tv_nexus);
> +		return -ENOMEM;
> +	}
> +	/*
> +	 * Since we are running in 'demo mode' this call with generate a
> +	 * struct se_node_acl for the tcm_vhost struct se_portal_group with
> +	 * the SCSI Initiator port name of the passed configfs group
'name'.
> +	 */
> +	tv_nexus->tvn_se_sess->se_node_acl =
core_tpg_check_initiator_node_acl(
> +				se_tpg, (unsigned char *)name);
> +	if (!tv_nexus->tvn_se_sess->se_node_acl) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		pr_debug("core_tpg_check_initiator_node_acl() failed"
> +				" for %s\n", name);
> +		transport_free_session(tv_nexus->tvn_se_sess);
> +		kfree(tv_nexus);
> +		return -ENOMEM;
> +	}
> +	/*
> +	 * Now register the TCM vHost virtual I_T Nexus as active with the
I think s/vHost/vhost/ would be nice :)
> +	 * call to __transport_register_session()
> +	 */
> +	__transport_register_session(se_tpg,
tv_nexus->tvn_se_sess->se_node_acl,
> +			tv_nexus->tvn_se_sess, tv_nexus);
> +	tv_tpg->tpg_nexus = tv_nexus;
> +
> +	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +	return 0;
> +}
> +
> +static int tcm_vhost_drop_nexus(
> +	struct tcm_vhost_tpg *tpg)
> +{
> +	struct se_session *se_sess;
> +	struct tcm_vhost_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 (atomic_read(&tpg->tv_tpg_port_count)) {
> +		mutex_unlock(&tpg->tv_tpg_mutex);
> +		pr_err("Unable to remove TCM_vHost I_T Nexus with"
> +			" active TPG port count: %d\n",
> +			atomic_read(&tpg->tv_tpg_port_count));
> +		return -EPERM;
EBUSY?

> +	}
> +
> +	if (atomic_read(&tpg->tv_tpg_vhost_count)) {
> +		mutex_unlock(&tpg->tv_tpg_mutex);
> +		pr_err("Unable to remove TCM_vHost I_T Nexus with"
> +			" active TPG vhost count: %d\n",
> +			atomic_read(&tpg->tv_tpg_vhost_count));
> +		return -EPERM;
Same?
> +	}
> +
> +	pr_debug("TCM_vHost_ConfigFS: Removing I_T Nexus to emulated"
> +		" %s Initiator Port: %s\n",
tcm_vhost_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
> +	 */
> +	transport_deregister_session(tv_nexus->tvn_se_sess);
> +	tpg->tpg_nexus = NULL;
> +	mutex_unlock(&tpg->tv_tpg_mutex);
> +
> +	kfree(tv_nexus);
> +	return 0;
> +}
> +
> +static ssize_t tcm_vhost_tpg_show_nexus(
> +	struct se_portal_group *se_tpg,
> +	char *page)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_nexus *tv_nexus;
> +	ssize_t ret;
> +
> +	mutex_lock(&tv_tpg->tv_tpg_mutex);
> +	tv_nexus = tv_tpg->tpg_nexus;
> +	if (!tv_nexus) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		return -ENODEV;
> +	}
> +	ret = snprintf(page, PAGE_SIZE, "%s\n",
> +			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
> +	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +
> +	return ret;
> +}
> +
> +static ssize_t tcm_vhost_tpg_store_nexus(
> +	struct se_portal_group *se_tpg,
> +	const char *page,
> +	size_t count)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport_wwn = tv_tpg->tport;
> +	unsigned char i_port[TCM_VHOST_NAMELEN], *ptr, *port_ptr;
> +	int ret;
> +	/*
> +	 * Shutdown the active I_T nexus if 'NULL' is passed..
> +	 */
> +	if (!strncmp(page, "NULL", 4)) {
> +		ret = tcm_vhost_drop_nexus(tv_tpg);
> +		return (!ret) ? count : ret;
> +	}
> +	/*
> +	 * Otherwise make sure the passed virtual Initiator port WWN matches
> +	 * the fabric protocol_id set in tcm_vhost_make_tport(), and call
> +	 * tcm_vhost_make_nexus().
> +	 */
> +	if (strlen(page) >= TCM_VHOST_NAMELEN) {
> +		pr_err("Emulated NAA Sas Address: %s, exceeds"
> +				" max: %d\n", page, TCM_VHOST_NAMELEN);
> +		return -EINVAL;
> +	}
> +	snprintf(&i_port[0], TCM_VHOST_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,
> +				tcm_vhost_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,
> +				tcm_vhost_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,
> +				tcm_vhost_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 = tcm_vhost_make_nexus(tv_tpg, port_ptr);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +TF_TPG_BASE_ATTR(tcm_vhost, nexus, S_IRUGO | S_IWUSR);
> +
> +static struct configfs_attribute *tcm_vhost_tpg_attrs[] = {
> +	&tcm_vhost_tpg_nexus.attr,
> +	NULL,
> +};
> +
> +static struct se_portal_group *tcm_vhost_make_tpg(
> +	struct se_wwn *wwn,
> +	struct config_group *group,
> +	const char *name)
> +{
> +	struct tcm_vhost_tport *tport = container_of(wwn,
> +			struct tcm_vhost_tport, tport_wwn);
> +
> +	struct tcm_vhost_tpg *tpg;
> +	unsigned long tpgt;
> +	int ret;
> +
> +	if (strstr(name, "tpgt_") != name)
> +		return ERR_PTR(-EINVAL);
> +	if (kstrtoul(name + 5, 10, &tpgt) || tpgt > UINT_MAX)
> +		return ERR_PTR(-EINVAL);
> +
> +	tpg = kzalloc(sizeof(struct tcm_vhost_tpg), GFP_KERNEL);
> +	if (!tpg) {
> +		pr_err("Unable to allocate struct tcm_vhost_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(&tcm_vhost_fabric_configfs->tf_ops, wwn,
> +				&tpg->se_tpg, tpg, TRANSPORT_TPG_TYPE_NORMAL);
> +	if (ret < 0) {
> +		kfree(tpg);
> +		return NULL;
> +	}
> +	mutex_lock(&tcm_vhost_mutex);
> +	list_add_tail(&tpg->tv_tpg_list, &tcm_vhost_list);
> +	mutex_unlock(&tcm_vhost_mutex);
> +
> +	return &tpg->se_tpg;
> +}
> +
> +static void tcm_vhost_drop_tpg(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +
> +	mutex_lock(&tcm_vhost_mutex);
> +	list_del(&tpg->tv_tpg_list);
> +	mutex_unlock(&tcm_vhost_mutex);
> +	/*
> +	 * Release the virtual I_T Nexus for this vHost TPG
> +	 */
> +	tcm_vhost_drop_nexus(tpg);
> +	/*
> +	 * Deregister the se_tpg from TCM..
> +	 */
> +	core_tpg_deregister(se_tpg);
> +	kfree(tpg);
> +}
> +
> +static struct se_wwn *tcm_vhost_make_tport(
> +	struct target_fabric_configfs *tf,
> +	struct config_group *group,
> +	const char *name)
> +{
> +	struct tcm_vhost_tport *tport;
> +	char *ptr;
> +	u64 wwpn = 0;
> +	int off = 0;
> +
> +	/* if (tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
> +		return ERR_PTR(-EINVAL); */
> +
> +	tport = kzalloc(sizeof(struct tcm_vhost_tport), GFP_KERNEL);
> +	if (!tport) {
> +		pr_err("Unable to allocate struct tcm_vhost_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) >= TCM_VHOST_NAMELEN) {
> +		pr_err("Emulated %s Address: %s, exceeds"
> +			" max: %d\n", name, tcm_vhost_dump_proto_id(tport),
> +			TCM_VHOST_NAMELEN);
> +		kfree(tport);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	snprintf(&tport->tport_name[0], TCM_VHOST_NAMELEN, "%s",
&name[off]);
> +
> +	pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
> +		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport), name);
> +
> +	return &tport->tport_wwn;
> +}
> +
> +static void tcm_vhost_drop_tport(struct se_wwn *wwn)
> +{
> +	struct tcm_vhost_tport *tport = container_of(wwn,
> +				struct tcm_vhost_tport, tport_wwn);
> +
> +	pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
> +		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport),
> +		tport->tport_name);
> +
> +	kfree(tport);
> +}
> +
> +static ssize_t tcm_vhost_wwn_show_attr_version(
> +	struct target_fabric_configfs *tf,
> +	char *page)
> +{
> +	return sprintf(page, "TCM_VHOST fabric module %s on %s/%s"
> +		"on "UTS_RELEASE"\n", TCM_VHOST_VERSION,
utsname()->sysname,
> +		utsname()->machine);
> +}
> +
> +TF_WWN_ATTR_RO(tcm_vhost, version);
> +
> +static struct configfs_attribute *tcm_vhost_wwn_attrs[] = {
> +	&tcm_vhost_wwn_version.attr,
> +	NULL,
> +};
> +
> +static struct target_core_fabric_ops tcm_vhost_ops = {
> +	.get_fabric_name		= tcm_vhost_get_fabric_name,
> +	.get_fabric_proto_ident		= tcm_vhost_get_fabric_proto_ident,
> +	.tpg_get_wwn			= tcm_vhost_get_fabric_wwn,
> +	.tpg_get_tag			= tcm_vhost_get_tag,
> +	.tpg_get_default_depth		= tcm_vhost_get_default_depth,
> +	.tpg_get_pr_transport_id	= tcm_vhost_get_pr_transport_id,
> +	.tpg_get_pr_transport_id_len	= tcm_vhost_get_pr_transport_id_len,
> +	.tpg_parse_pr_out_transport_id	= tcm_vhost_parse_pr_out_transport_id,
> +	.tpg_check_demo_mode		= tcm_vhost_check_true,
> +	.tpg_check_demo_mode_cache	= tcm_vhost_check_true,
> +	.tpg_check_demo_mode_write_protect = tcm_vhost_check_false,
> +	.tpg_check_prod_mode_write_protect = tcm_vhost_check_false,
> +	.tpg_alloc_fabric_acl		= tcm_vhost_alloc_fabric_acl,
> +	.tpg_release_fabric_acl		= tcm_vhost_release_fabric_acl,
> +	.tpg_get_inst_index		= tcm_vhost_tpg_get_inst_index,
> +	.release_cmd			= tcm_vhost_release_cmd,
> +	.shutdown_session		= tcm_vhost_shutdown_session,
> +	.close_session			= tcm_vhost_close_session,
> +	.sess_get_index			= tcm_vhost_sess_get_index,
> +	.sess_get_initiator_sid		= NULL,
> +	.write_pending			= tcm_vhost_write_pending,
> +	.write_pending_status		= tcm_vhost_write_pending_status,
> +	.set_default_node_attributes	= tcm_vhost_set_default_node_attrs,
> +	.get_task_tag			= tcm_vhost_get_task_tag,
> +	.get_cmd_state			= tcm_vhost_get_cmd_state,
> +	.queue_data_in			= tcm_vhost_queue_data_in,
> +	.queue_status			= tcm_vhost_queue_status,
> +	.queue_tm_rsp			= tcm_vhost_queue_tm_rsp,
> +	.get_fabric_sense_len		= tcm_vhost_get_fabric_sense_len,
> +	.set_fabric_sense_len		= tcm_vhost_set_fabric_sense_len,
> +	/*
> +	 * Setup callers for generic logic in target_core_fabric_configfs.c
> +	 */
> +	.fabric_make_wwn		= tcm_vhost_make_tport,
> +	.fabric_drop_wwn		= tcm_vhost_drop_tport,
> +	.fabric_make_tpg		= tcm_vhost_make_tpg,
> +	.fabric_drop_tpg		= tcm_vhost_drop_tpg,
> +	.fabric_post_link		= tcm_vhost_port_link,
> +	.fabric_pre_unlink		= tcm_vhost_port_unlink,
> +	.fabric_make_np			= NULL,
> +	.fabric_drop_np			= NULL,
> +	.fabric_make_nodeacl		= tcm_vhost_make_nodeacl,
> +	.fabric_drop_nodeacl		= tcm_vhost_drop_nodeacl,
> +};
> +
> +static int tcm_vhost_register_configfs(void)
> +{
> +	struct target_fabric_configfs *fabric;
> +	int ret;
> +
> +	pr_debug("TCM_VHOST fabric module %s on %s/%s"
> +		" on "UTS_RELEASE"\n", TCM_VHOST_VERSION,
utsname()->sysname,
> +		utsname()->machine);
> +	/*
> +	 * Register the top level struct config_item_type with TCM core
> +	 */
> +	fabric = target_fabric_configfs_init(THIS_MODULE, "vhost");
> +	if (IS_ERR(fabric)) {
> +		pr_err("target_fabric_configfs_init() failed\n");
> +		return PTR_ERR(fabric);
> +	}
> +	/*
> +	 * Setup fabric->tf_ops from our local tcm_vhost_ops
> +	 */
> +	fabric->tf_ops = tcm_vhost_ops;
> +	/*
> +	 * Setup default attribute lists for various fabric->tf_cit_tmpl
> +	 */
> +	TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = tcm_vhost_wwn_attrs;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = tcm_vhost_tpg_attrs;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_base_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_param_cit.ct_attrs = NULL;
> +	/*
> +	 * Register the fabric for use within TCM
> +	 */
> +	ret = target_fabric_configfs_register(fabric);
> +	if (ret < 0) {
> +		pr_err("target_fabric_configfs_register() failed"
> +				" for TCM_VHOST\n");
> +		return ret;
> +	}
> +	/*
> +	 * Setup our local pointer to *fabric
> +	 */
> +	tcm_vhost_fabric_configfs = fabric;
> +	pr_debug("TCM_VHOST[0] - Set fabric ->
tcm_vhost_fabric_configfs\n");
> +	return 0;
> +};
> +
> +static void tcm_vhost_deregister_configfs(void)
> +{
> +	if (!tcm_vhost_fabric_configfs)
> +		return;
> +
> +	target_fabric_configfs_deregister(tcm_vhost_fabric_configfs);
> +	tcm_vhost_fabric_configfs = NULL;
> +	pr_debug("TCM_VHOST[0] - Cleared tcm_vhost_fabric_configfs\n");
> +};
> +
> +static int __init tcm_vhost_init(void)
> +{
> +	int ret = -ENOMEM;
> +
> +	tcm_vhost_workqueue = alloc_workqueue("tcm_vhost", 0, 0);
> +	if (!tcm_vhost_workqueue)
> +		goto out;
Pls add a comment explaining why we need our own workqueue
and aren't using the system one instead.
> +
> +	ret = vhost_scsi_register();
> +	if (ret < 0)
> +		goto out_destroy_workqueue;
> +
> +	ret = tcm_vhost_register_configfs();
> +	if (ret < 0)
> +		goto out_vhost_scsi_deregister;
> +
> +	return 0;
> +
> +out_vhost_scsi_deregister:
> +	vhost_scsi_deregister();
> +out_destroy_workqueue:
> +	destroy_workqueue(tcm_vhost_workqueue);
> +out:
> +	return ret;
> +};
> +
> +static void tcm_vhost_exit(void)
> +{
> +	tcm_vhost_deregister_configfs();
> +	vhost_scsi_deregister();
> +	destroy_workqueue(tcm_vhost_workqueue);
> +};
> +
> +MODULE_DESCRIPTION("TCM_VHOST series fabric driver");
> +MODULE_LICENSE("GPL");
> +module_init(tcm_vhost_init);
> +module_exit(tcm_vhost_exit);
> diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
> new file mode 100644
> index 0000000..c983ed2
> --- /dev/null
> +++ b/drivers/vhost/tcm_vhost.h
> @@ -0,0 +1,101 @@
> +#define TCM_VHOST_VERSION  "v0.1"
> +#define TCM_VHOST_NAMELEN 256
> +#define TCM_VHOST_MAX_CDB_SIZE 32
> +
> +struct tcm_vhost_cmd {
> +	/* Descriptor from vhost_get_vq_desc() for virt_queue segment */
> +	int tvc_vq_desc;
> +	/* 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;
> +	/* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
> +	u32 tvc_lun;
> +	/* Pointer to the SGL formatted memory from virtio-scsi */
> +	struct scatterlist *tvc_sgl;
> +	/* Pointer to response */
> +	struct virtio_scsi_cmd_resp __user *tvc_resp;
> +	/* Pointer to vhost_scsi for our device */
> +	struct vhost_scsi *tvc_vhost;
> +	/* The TCM I/O descriptor that is accessed via container_of() */
> +	struct se_cmd tvc_se_cmd;
> +	/* work item used for cmwq dispatch to tcm_vhost_submission_work() */
> +	struct work_struct work;
> +	/* Copy of the incoming SCSI command descriptor block (CDB) */
> +	unsigned char tvc_cdb[TCM_VHOST_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 list_head tvc_completion_list;
> +};
> +
> +struct tcm_vhost_nexus {
> +	/* Pointer to TCM session for I_T Nexus */
> +	struct se_session *tvn_se_sess;
> +};
> +
> +struct tcm_vhost_nacl {
> +	/* Binary World Wide unique Port Name for Vhost Initiator port */
> +	u64 iport_wwpn;
> +	/* ASCII formatted WWPN for Sas Initiator port */
> +	char iport_name[TCM_VHOST_NAMELEN];
> +	/* Returned by tcm_vhost_make_nodeacl() */
> +	struct se_node_acl se_node_acl;
> +};
> +
> +struct tcm_vhost_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 */
> +	atomic_t tv_tpg_port_count;
> +	/* Used for vhost_scsi device reference to tpg_nexus */
> +	atomic_t tv_tpg_vhost_count;
> +	/* list for tcm_vhost_list */
> +	struct list_head tv_tpg_list;
> +	/* Used to protect access for tpg_nexus */
> +	struct mutex tv_tpg_mutex;
would it be easier to just use dev mutex instead?
> +	/* Pointer to the TCM VHost I_T Nexus for this TPG endpoint */
> +	struct tcm_vhost_nexus *tpg_nexus;
> +	/* Pointer back to tcm_vhost_tport */
> +	struct tcm_vhost_tport *tport;
> +	/* Returned by tcm_vhost_make_tpg() */
> +	struct se_portal_group se_tpg;
> +};
> +
> +struct tcm_vhost_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[TCM_VHOST_NAMELEN];
> +	/* Returned by tcm_vhost_make_tport() */
> +	struct se_wwn tport_wwn;
> +};
> +
> +/*
> + * As per request from MST, keep TCM_VHOST related ioctl defines out of
> + * linux/vhost.h (user-space) for now..
> + */
> +
> +#include <linux/vhost.h>
> +
> +/*
> + * Used by QEMU userspace to ensure a consistent vhost-scsi ABI.
> + *
> + * ABI Rev 0: July 2012 version starting point for v3.6-rc merge candidate
+
> + *            RFC-v2 vhost-scsi userspace.  Add GET_ABI_VERSION ioctl
usage
> + */
> +
> +#define VHOST_SCSI_ABI_VERSION	0
> +
> +struct vhost_scsi_target {
> +	int abi_version;
> +	unsigned char vhost_wwpn[TRANSPORT_IQN_LEN];
> +	unsigned short vhost_tpgt;
> +};
> +
> +/* VHOST_SCSI specific defines */
> +#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct
vhost_scsi_target)
> +#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct
vhost_scsi_target)
> +#define VHOST_SCSI_GET_ABI_VERSION _IOW(VHOST_VIRTIO, 0x42, struct
vhost_scsi_target)
CLEAR_ENDPOINT and SET_ENDPOINT commands get an abi version
too but it's ignored there. Intentional?
Why not
#define VHOST_SCSI_GET_ABI_VERSION _IOW(VHOST_VIRTIO, 0x42, int)
and then you avoid changing vhost_scsi_target ...

Also, let's add a comment like

/* Changing this breaks userspace. */

so we remember never to change this value.
> -- 
> 1.7.2.5

On Thu, Jul 26, 2012 at 4:43 PM, Nicholas A. Bellinger
<nab at linux-iscsi.org>wrote:
> [...]
> +static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
> +{
> +       struct vhost_virtqueue *vq = &vs->vqs[2];
> +       struct virtio_scsi_cmd_req v_req;
> +       struct tcm_vhost_tpg *tv_tpg;
> +       struct tcm_vhost_cmd *tv_cmd;
> +       u32 exp_data_len, data_first, data_num, data_direction;
> +       unsigned out, in, i;
> +       int head, ret;
> +
> +       /* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
> +       tv_tpg = vs->vs_tpg;
> +       if (unlikely(!tv_tpg)) {
> +               pr_err("%s endpoint not set\n", __func__);
> +               return;
> +       }
> +
> +       mutex_lock(&vq->mutex);
> +       vhost_disable_notify(&vs->dev, vq);
> +
> +       for (;;) {
> +               head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
> +                                       ARRAY_SIZE(vq->iov), &out,
&in,
> +                                       NULL, NULL);
> +               pr_debug("vhost_get_vq_desc: head: %d, out: %u in:
%u\n",
> +                                       head, out, in);
> +               /* 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(&vs->dev,
vq))) {
> +                               vhost_disable_notify(&vs->dev, vq);
> +                               continue;
> +                       }
> +                       break;
> +               }
> +
> +/* FIXME: BIDI operation */
> +               if (out == 1 && in == 1) {
>
It seems to me like this is not the way that virtio devices are supposed to
behave - if a guest splits a virtio_scsi_cmd_req or _resp across a page
boundary, then this code won't work.

Quoting the 'Message Framing' part of the virtio spec:

"In particular, no implementation should use the descriptor boundaries to
determine the size of any header in a request. "


+                       data_direction = DMA_NONE;
> +                       data_first = 0;
> +                       data_num = 0;
> +               } else if (out == 1 && in > 1) {
> +                       data_direction = DMA_FROM_DEVICE;
> +                       data_first = out + 1;
> +                       data_num = in - 1;
> +               } else if (out > 1 && in == 1) {
> +                       data_direction = DMA_TO_DEVICE;
> +                       data_first = 1;
> +                       data_num = out - 1;
> +               } else {
> +                       vq_err(vq, "Invalid buffer layout out: %u in:
> %u\n",
> +                                       out, in);
> +                       break;
> +               }
> +
> +               /*
> +                * Check for a sane resp buffer so we can report errors to
> +                * the guest.
> +                */
> +               if (unlikely(vq->iov[out].iov_len !> +               
sizeof(struct
> virtio_scsi_cmd_resp))) {
> +                       vq_err(vq, "Expecting virtio_scsi_cmd_resp,
got
> %zu"
> +                               " bytes\n",
vq->iov[out].iov_len);
> +                       break;
> +               }
> +
> +               if (unlikely(vq->iov[0].iov_len != sizeof(v_req))) {
> +                       vq_err(vq, "Expecting virtio_scsi_cmd_req, got
%zu"
> +                               " bytes\n",
vq->iov[0].iov_len);
> +                       break;
> +               }
> +               pr_debug("Calling __copy_from_user:
vq->iov[0].iov_base:
> %p,"
> +                       " len: %zu\n", vq->iov[0].iov_base,
sizeof(v_req));
> +               ret = __copy_from_user(&v_req, vq->iov[0].iov_base,
> +                               sizeof(v_req));
> +               if (unlikely(ret)) {
> +                       vq_err(vq, "Faulted on
virtio_scsi_cmd_req\n");
> +                       break;
> +               }
> +
> +               exp_data_len = 0;
> +               for (i = 0; i < data_num; i++)
> +                       exp_data_len += vq->iov[data_first + i].iov_len;
> +
> +               tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
> +                                       exp_data_len, data_direction);
> +               if (IS_ERR(tv_cmd)) {
> +                       vq_err(vq, "vhost_scsi_allocate_cmd failed
%ld\n",
> +                                       PTR_ERR(tv_cmd));
> +                       break;
> +               }
> +               pr_debug("Allocated tv_cmd: %p exp_data_len: %d,
> data_direction"
> +                       ": %d\n", tv_cmd, exp_data_len,
data_direction);
> +
> +               tv_cmd->tvc_vhost = vs;
> +
> +               if (unlikely(vq->iov[out].iov_len !> +               
sizeof(struct virtio_scsi_cmd_resp))) {
> +                       vq_err(vq, "Expecting virtio_scsi_cmd_resp,
got
> %zu"
> +                               " bytes, out: %d, in: %d\n",
> +                               vq->iov[out].iov_len, out, in);
> +                       break;
> +               }
> +
> +               tv_cmd->tvc_resp = vq->iov[out].iov_base;
> +
> +               /*
> +                * Copy in the recieved CDB descriptor into
tv_cmd->tvc_cdb
> +                * that will be used by tcm_vhost_new_cmd_map() and down
> into
> +                * target_setup_cmd_from_cdb()
> +                */
> +               memcpy(tv_cmd->tvc_cdb, v_req.cdb,
TCM_VHOST_MAX_CDB_SIZE);
> +               /*
> +                * Check that the recieved CDB size does not exceeded our
> +                * hardcoded max for tcm_vhost
> +                */
> +               /* TODO what if cdb was too small for varlen cdb header? */
> +               if (unlikely(scsi_command_size(tv_cmd->tvc_cdb) >
> +                                       TCM_VHOST_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(tv_cmd->tvc_cdb),
> +                               TCM_VHOST_MAX_CDB_SIZE);
> +                       break; /* TODO */
> +               }
> +               tv_cmd->tvc_lun = ((v_req.lun[2] << 8) |
v_req.lun[3]) &
> 0x3FFF;
> +
> +               pr_debug("vhost_scsi got command opcode: %#02x, lun:
%d\n",
> +                       tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun);
> +
> +               if (data_direction != DMA_NONE) {
> +                       ret = vhost_scsi_map_iov_to_sgl(tv_cmd,
> +                                       &vq->iov[data_first],
data_num,
> +                                       data_direction == DMA_TO_DEVICE);
> +                       if (unlikely(ret)) {
> +                               vq_err(vq, "Failed to map iov to
sgl\n");
> +                               break; /* TODO */
> +                       }
> +               }
> +
> +               /*
> +                * Save the descriptor from vhost_get_vq_desc() to be used
> to
> +                * complete the virtio-scsi request in TCM callback
> context via
> +                * tcm_vhost_queue_data_in() and tcm_vhost_queue_status()
> +                */
> +               tv_cmd->tvc_vq_desc = head;
> +               /*
> +                * Dispatch tv_cmd descriptor for cmwq execution in process
> +                * context provided by tcm_vhost_workqueue.  This also
> ensures
> +                * tv_cmd is executed on the same kworker CPU as this vhost
> +                * thread to gain positive L2 cache locality effects..
> +                */
> +               INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work);
> +               queue_work(tcm_vhost_workqueue, &tv_cmd->work);
> +       }
> +
> +       mutex_unlock(&vq->mutex);
> +}
> [...]
> --
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>


-- 
Typing one-handed, please don't mistake brevity for rudeness.
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