[dpdk-dev,v3] examples/vhost: introduce a new vhost-user-scsi sample application

Message ID 1499491297-17800-1-git-send-email-changpeng.liu@intel.com (mailing list archive)
State Accepted, archived
Delegated to: Yuanhan Liu
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation fail Compilation issues

Commit Message

Liu, Changpeng July 8, 2017, 5:21 a.m. UTC
  vhost-user protocol is common to many virtio devices, such as
virtio_net/virtio_scsi/virtio_blk. Since DPDK vhost library
removed the NET specific data structures, the vhost library
is common to other virtio devices, such as virtio-scsi.

Here we introduce a simple memory based block device that
can be presented to Guest VM through vhost-user-scsi-pci
controller. Similar with vhost-net, the sample application
will process the I/Os sent via virt rings.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
---
 MAINTAINERS                             |   2 +
 doc/guides/sample_app_ug/vhost_scsi.rst | 110 +++++++
 examples/Makefile                       |   2 +-
 examples/vhost_scsi/Makefile            |  59 ++++
 examples/vhost_scsi/scsi.c              | 507 ++++++++++++++++++++++++++++++++
 examples/vhost_scsi/scsi_spec.h         | 488 ++++++++++++++++++++++++++++++
 examples/vhost_scsi/vhost_scsi.c        | 472 +++++++++++++++++++++++++++++
 examples/vhost_scsi/vhost_scsi.h        | 250 ++++++++++++++++
 8 files changed, 1889 insertions(+), 1 deletion(-)
 create mode 100644 doc/guides/sample_app_ug/vhost_scsi.rst
 create mode 100644 examples/vhost_scsi/Makefile
 create mode 100644 examples/vhost_scsi/scsi.c
 create mode 100644 examples/vhost_scsi/scsi_spec.h
 create mode 100644 examples/vhost_scsi/vhost_scsi.c
 create mode 100644 examples/vhost_scsi/vhost_scsi.h
  

Comments

Yuanhan Liu July 7, 2017, 5:07 a.m. UTC | #1
On Sat, Jul 08, 2017 at 01:21:37PM +0800, Changpeng Liu wrote:
> vhost-user protocol is common to many virtio devices, such as
> virtio_net/virtio_scsi/virtio_blk. Since DPDK vhost library
> removed the NET specific data structures, the vhost library
> is common to other virtio devices, such as virtio-scsi.
> 
> Here we introduce a simple memory based block device that
> can be presented to Guest VM through vhost-user-scsi-pci
> controller. Similar with vhost-net, the sample application
> will process the I/Os sent via virt rings.
> 
> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>

Applied to dpdk-next-virtio.

Thanks.

	--yliu
  
Hemant Agrawal July 7, 2017, 8:40 a.m. UTC | #2
On 7/7/2017 10:37 AM, Yuanhan Liu wrote:
> On Sat, Jul 08, 2017 at 01:21:37PM +0800, Changpeng Liu wrote:
>> vhost-user protocol is common to many virtio devices, such as
>> virtio_net/virtio_scsi/virtio_blk. Since DPDK vhost library
>> removed the NET specific data structures, the vhost library
>> is common to other virtio devices, such as virtio-scsi.
>>
>> Here we introduce a simple memory based block device that
>> can be presented to Guest VM through vhost-user-scsi-pci
>> controller. Similar with vhost-net, the sample application
>> will process the I/Os sent via virt rings.
>>
>> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
>
> Applied to dpdk-next-virtio.
>

Though my comment is late.
I am just wondering if it is not better to refactor the existing vhost 
applications and add this as a mode instead of adding one more sample 
application?

> Thanks.
>
> 	--yliu
>
  
Yuanhan Liu July 7, 2017, 9:44 a.m. UTC | #3
On Fri, Jul 07, 2017 at 02:10:57PM +0530, Hemant Agrawal wrote:
> On 7/7/2017 10:37 AM, Yuanhan Liu wrote:
> >On Sat, Jul 08, 2017 at 01:21:37PM +0800, Changpeng Liu wrote:
> >>vhost-user protocol is common to many virtio devices, such as
> >>virtio_net/virtio_scsi/virtio_blk. Since DPDK vhost library
> >>removed the NET specific data structures, the vhost library
> >>is common to other virtio devices, such as virtio-scsi.
> >>
> >>Here we introduce a simple memory based block device that
> >>can be presented to Guest VM through vhost-user-scsi-pci
> >>controller. Similar with vhost-net, the sample application
> >>will process the I/Os sent via virt rings.
> >>
> >>Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> >
> >Applied to dpdk-next-virtio.
> >
> 
> Though my comment is late.
> I am just wondering if it is not better to refactor the existing vhost
> applications and add this as a mode instead of adding one more sample
> application?

Ideally, yes. However, I don't find a straightforward way to do that
for this scsi example, for following reasons:

- Current vhost switch example was not well designed. Worse, it has
  has few NIC features bond, say VMDq and VLAN.

- Vhost switch is for networking, while this one is for storage. To
  let them co-exist in one app, we have to firstly refactor current
  vhost-user example, which should be a big rework that I don't think
  it's worthwhile.

Or, maybe we could put vhost_switch and vhost_scsi into one dir (say
"vhost") under examples and let them look like one example (with 2
standalone apps), like what we did for multi_process examples?

And we probably could do more, for example, the l2fwd, l3fwd and
their variants?

However, IMO, it just make the examples dir more cleanly, nothing
else. Except someone will spend more time to refactor them, such as
removing the duplicate code and introduce them as helper functions.
Again, It may not be that worthwhile, judging that they are just
examples.

	--yliu
  
Thomas Monjalon July 7, 2017, 12:21 p.m. UTC | #4
08/07/2017 07:21, Changpeng Liu:
>  MAINTAINERS                             |   2 +
>  doc/guides/sample_app_ug/vhost_scsi.rst | 110 +++++++
>  examples/Makefile                       |   2 +-
>  examples/vhost_scsi/Makefile            |  59 ++++
>  examples/vhost_scsi/scsi.c              | 507 ++++++++++++++++++++++++++++++++
>  examples/vhost_scsi/scsi_spec.h         | 488 ++++++++++++++++++++++++++++++
>  examples/vhost_scsi/vhost_scsi.c        | 472 +++++++++++++++++++++++++++++
>  examples/vhost_scsi/vhost_scsi.h        | 250 ++++++++++++++++
>  8 files changed, 1889 insertions(+), 1 deletion(-)

I think you are missing to update the doc index.
  
Yuanhan Liu July 8, 2017, 2:53 a.m. UTC | #5
On Fri, Jul 07, 2017 at 02:21:28PM +0200, Thomas Monjalon wrote:
> 08/07/2017 07:21, Changpeng Liu:
> >  MAINTAINERS                             |   2 +
> >  doc/guides/sample_app_ug/vhost_scsi.rst | 110 +++++++
> >  examples/Makefile                       |   2 +-
> >  examples/vhost_scsi/Makefile            |  59 ++++
> >  examples/vhost_scsi/scsi.c              | 507 ++++++++++++++++++++++++++++++++
> >  examples/vhost_scsi/scsi_spec.h         | 488 ++++++++++++++++++++++++++++++
> >  examples/vhost_scsi/vhost_scsi.c        | 472 +++++++++++++++++++++++++++++
> >  examples/vhost_scsi/vhost_scsi.h        | 250 ++++++++++++++++
> >  8 files changed, 1889 insertions(+), 1 deletion(-)
> 
> I think you are missing to update the doc index.

Oops, right, and fixed.

Thanks!

	--yliu
  
Thomas Monjalon July 9, 2017, 4:42 p.m. UTC | #6
08/07/2017 07:21, Changpeng Liu:
> vhost-user protocol is common to many virtio devices, such as
> virtio_net/virtio_scsi/virtio_blk. Since DPDK vhost library
> removed the NET specific data structures, the vhost library
> is common to other virtio devices, such as virtio-scsi.
> 
> Here we introduce a simple memory based block device that
> can be presented to Guest VM through vhost-user-scsi-pci
> controller. Similar with vhost-net, the sample application
> will process the I/Os sent via virt rings.
> 
> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> ---

Just checked the compilation, it fails for 32-bit.
  
Wodkowski, PawelX July 12, 2017, 2:49 p.m. UTC | #7
Hi, sorry for late review but just spotted this patch.
Please see my comments

> diff --git a/examples/vhost_scsi/scsi.c b/examples/vhost_scsi/scsi.c
> new file mode 100644
> index 0000000..08dfe61
> --- /dev/null
> +++ b/examples/vhost_scsi/scsi.c
> @@ -0,0 +1,507 @@

> +static int
> +vhost_hex2bin(char ch)
> +{
> +	if ((ch >= '0') && (ch <= '9'))
> +		return ch - '0';
> +	ch = tolower(ch);
> +	if ((ch >= 'a') && (ch <= 'f'))
> +		return ch - 'a' + 10;
> +	return (int)ch;
> +}

consider using strtol()

> +
> +int
> +vhost_bdev_process_scsi_commands(struct vhost_block_dev *bdev,
> +				 struct vhost_scsi_task *task)
> +{
> +	int len;
> +	uint8_t *data;
> +	uint64_t fmt_lun = 0;
> +	const uint8_t *lun;
> +	uint8_t *cdb = (uint8_t *)task->req->cdb;
> +
> +	lun = (const uint8_t *)task->req->lun;
> +	/* only 1 LUN supported */
> +	if (lun[0] != 1 || lun[1] >= 1)
> +		return -1;
> +
> +	switch (cdb[0]) {
> +	case SPC_INQUIRY:
> +		len = vhost_bdev_scsi_inquiry_command(bdev, task);
> +		task->data_len = len;
> +		break;
> +	case SPC_REPORT_LUNS:
> +		data = (uint8_t *)task->iovs[0].iov_base;
> +		fmt_lun |= (0x0ULL & 0x00ffULL) << 48;

Please provide a description for this magical formula for non-SCSI proficient community.

> +		to_be64((void *)&data[8], fmt_lun);
> +		to_be32((void *)data, 8);
> +		task->data_len = 16;
> +		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
> +		break;
> +	case SPC_MODE_SELECT_6:
> +	case SPC_MODE_SELECT_10:
> +		/* TODO: Add SCSI Commands support */
> +		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
> +		break;
> +	case SPC_MODE_SENSE_6:
> +	case SPC_MODE_SENSE_10:
> +		/* TODO: Add SCSI Commands support */
> +		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
> +		break;

If those cases are mandatory they should be implemented if not removing TODO would be better than informing that
there is something to do.

> +	case SPC_TEST_UNIT_READY:
> +		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
> +		break;
> +	default:
> +		len = vhost_bdev_scsi_process_block(bdev, task);
> +		task->data_len = len;
> +	}
> +
> +	return 0;
> +}
> diff --git a/examples/vhost_scsi/scsi_spec.h b/examples/vhost_scsi/scsi_spec.h
> new file mode 100644
> index 0000000..0474d92
> --- /dev/null
> +++ b/examples/vhost_scsi/scsi_spec.h
> @@ -0,0 +1,488 @@

Most of the scsi_spec.h file is unused, please remove unnecessary parts. 

> diff --git a/examples/vhost_scsi/vhost_scsi.c
> b/examples/vhost_scsi/vhost_scsi.c
> new file mode 100644
> index 0000000..160c2e0
> --- /dev/null
> +++ b/examples/vhost_scsi/vhost_scsi.c
> @@ -0,0 +1,472 @@

> +
> +#define VIRTIO_SCSI_FEATURES ((1 << VIRTIO_F_NOTIFY_ON_EMPTY) |\
> +			      (1 << VIRTIO_RING_F_EVENT_IDX) |\

Am I missing something or this example app doesn't support EVENT_IDX?

> +			      (1 << VIRTIO_SCSI_F_INOUT) |\
> +			      (1 << VIRTIO_SCSI_F_CHANGE))
> +
> +/* Path to folder where character device will be created. Can be set by user.
> */
> +static char dev_pathname[PATH_MAX] = "";
> +
> +static struct vhost_scsi_ctrlr *g_vhost_ctrlr;
> +static int g_should_stop;
> +static sem_t exit_sem;
> +
> +#define NUM_OF_SCSI_QUEUES 3
> +
> +static struct vhost_scsi_ctrlr *
> +vhost_scsi_ctrlr_find(__rte_unused const char *ctrlr_name)
> +{
> +	/* currently we only support 1 socket file fd */

So remove this function.

> +	return g_vhost_ctrlr;
> +}
> +
> +static uint64_t gpa_to_vva(int vid, uint64_t gpa)
> +{
> +	char path[PATH_MAX];
> +	struct vhost_scsi_ctrlr *ctrlr;
> +	int ret = 0;
> +
> +	ret = rte_vhost_get_ifname(vid, path, PATH_MAX);
> +	if (ret) {
> +		fprintf(stderr, "Cannot get socket name\n");
> +		assert(ret != 0);
> +	}
> +
> +	ctrlr = vhost_scsi_ctrlr_find(path);
> +	if (!ctrlr) {
> +		fprintf(stderr, "Controller is not ready\n");
> +		assert(ctrlr != NULL);
> +	}
> +
> +	assert(ctrlr->mem != NULL);
> +
> +	return rte_vhost_gpa_to_vva(ctrlr->mem, gpa);
> +}
> +

Replace vid in  vhost_block_dev by pointer to struct vhost_scsi_ctrlr
This way you will not need this whole function at all.

> +static struct vring_desc *
> +descriptor_get_next(struct vring_desc *vq_desc, struct vring_desc
> *cur_desc)
> +{
> +	return &vq_desc[cur_desc->next];
> +}
> +
> +static bool
> +descriptor_has_next(struct vring_desc *cur_desc)
> +{
> +	return !!(cur_desc->flags & VRING_DESC_F_NEXT);
> +}
> +
> +static bool
> +descriptor_is_wr(struct vring_desc *cur_desc)
> +{
> +	return !!(cur_desc->flags & VRING_DESC_F_WRITE);
> +}

I have an impression that all those functions should go to library instead of example application.

> +
> +static struct vhost_block_dev *
> +vhost_scsi_bdev_construct(const char *bdev_name, const char
> *bdev_serial,
> +			  uint32_t blk_size, uint64_t blk_cnt,
> +			  bool wce_enable)
> +{
> +	struct vhost_block_dev *bdev;
> +
> +	bdev = rte_zmalloc(NULL, sizeof(*bdev), RTE_CACHE_LINE_SIZE);
> +	if (!bdev)
> +		return NULL;
> +
> +	strncpy(bdev->name, bdev_name, sizeof(bdev->name));
> +	strncpy(bdev->product_name, bdev_serial, sizeof(bdev-
> >product_name));
> +	bdev->blocklen = blk_size;
> +	bdev->blockcnt = blk_cnt;
> +	bdev->write_cache = wce_enable;

write_cache is not used and should be removed.

> +
> +	/* use memory as disk storage space */
> +	bdev->data = rte_zmalloc(NULL, blk_cnt * blk_size, 0);
> +	if (!bdev->data) {
> +		fprintf(stderr, "no enough reseverd huge memory for
> disk\n");
> +		return NULL;
> +	}
> +
> +	return bdev;
> +}
> +
> +static void
> +process_requestq(struct vhost_scsi_ctrlr *ctrlr, uint32_t q_idx)
> +{
> +	int ret;
> +	struct vhost_scsi_queue *scsi_vq;
> +	struct rte_vhost_vring *vq;
> +
> +	scsi_vq = &ctrlr->bdev->queues[q_idx];
> +	vq = &scsi_vq->vq;
> +	ret = rte_vhost_get_vhost_vring(ctrlr->bdev->vid, q_idx, vq);
> +	assert(ret == 0);
> +
> +	while (vq->avail->idx != scsi_vq->last_used_idx) {
> +		int req_idx;
> +		uint16_t last_idx;
> +		struct vhost_scsi_task *task;
> +
> +		last_idx = scsi_vq->last_used_idx & (vq->size - 1);
> +		req_idx = vq->avail->ring[last_idx];
> +
> +		task = rte_zmalloc(NULL, sizeof(*task), 0);
> +		assert(task != NULL);
> +
> +		task->ctrlr = ctrlr;
> +		task->bdev = ctrlr->bdev;
> +		task->vq = vq;
> +		task->req_idx = req_idx;
> +		task->desc = &task->vq->desc[task->req_idx];
> +
> +		/* does not support indirect descriptors */
> +		assert((task->desc->flags & VRING_DESC_F_INDIRECT) == 0);
> +		scsi_vq->last_used_idx++;
> +
> +		task->req = (void *)gpa_to_vva(task->bdev->vid,
> +					       task->desc->addr);
> +
> +		task->desc = descriptor_get_next(task->vq->desc, task-
> >desc);
> +		if (!descriptor_has_next(task->desc)) {
> +			task->dxfer_dir = SCSI_DIR_NONE;
> +			task->resp = (void *)gpa_to_vva(task->bdev->vid,
> +							task->desc->addr);
> +
> +		} else if (!descriptor_is_wr(task->desc)) {
> +			task->dxfer_dir = SCSI_DIR_TO_DEV;
> +			vhost_process_write_payload_chain(task);
> +		} else {
> +			task->dxfer_dir = SCSI_DIR_FROM_DEV;
> +			vhost_process_read_payload_chain(task);
> +		}
> +
> +		ret = vhost_bdev_process_scsi_commands(ctrlr->bdev,
> task);
> +		if (ret) {
> +			/* invalid response */
> +			task->resp->response =
> VIRTIO_SCSI_S_BAD_TARGET;
> +		} else {
> +			/* successfully */
> +			task->resp->response = VIRTIO_SCSI_S_OK;
> +			task->resp->status = 0;

You need to fill resp->resid field here.

> +		}
> +		submit_completion(task);
> +		rte_free(task);
> +	}
> +}
> +
> +/* Main framework for processing IOs */
> +static void *
> +ctrlr_worker(void *arg)
> +{
> +	uint32_t idx, num;
> +	struct vhost_scsi_ctrlr *ctrlr = (struct vhost_scsi_ctrlr *)arg;
> +	cpu_set_t cpuset;
> +	pthread_t thread;
> +
> +	thread = pthread_self();
> +	CPU_ZERO(&cpuset);
> +	CPU_SET(0, &cpuset);
> +	pthread_setaffinity_np(thread, sizeof(cpu_set_t), &cpuset);
> +
> +	num =  rte_vhost_get_vring_num(ctrlr->bdev->vid);
> +	fprintf(stdout, "Ctrlr Worker Thread Started with %u Vring\n", num);
> +
> +	if (num != NUM_OF_SCSI_QUEUES) {

Again, how many queues doeas this app support 8 or NUM_OF_SCSI_QUEUES?

> +		fprintf(stderr, "Only 1 IO queue are supported\n");
> +		exit(0);
> +	}
> +
> +	while (!g_should_stop && ctrlr->bdev != NULL) {
> +		/* At least 3 vrings, currently only can support 1 IO queue
> +		 * Queue 2 for IO queue, does not support TMF and hotplug
> +		 * for the example application now
> +		 */
> +		for (idx = 2; idx < num; idx++)
> +			process_requestq(ctrlr, idx);
> +	}
> +
> +	fprintf(stdout, "Ctrlr Worker Thread Exiting\n");
> +	sem_post(&exit_sem);
> +	return NULL;
> +}
> +

> +
> +static struct vhost_scsi_ctrlr *
> +vhost_scsi_ctrlr_construct(const char *ctrlr_name)
> +{
> +	int ret;
> +	struct vhost_scsi_ctrlr *ctrlr;
> +	char *path;
> +	char cwd[PATH_MAX];
> +
> +	/* always use current directory */
> +	path = getcwd(cwd, PATH_MAX);
> +	if (!path) {
> +		fprintf(stderr, "Cannot get current working directory\n");
> +		return NULL;
> +	}
> +	snprintf(dev_pathname, sizeof(dev_pathname), "%s/%s", path,
> ctrlr_name);
> +
> +	if (access(dev_pathname, F_OK) != -1) {
> +		if (unlink(dev_pathname) != 0)
> +			rte_exit(EXIT_FAILURE, "Cannot remove %s.\n",
> +				 dev_pathname);
> +	}
> +
> +	fprintf(stdout, "socket file: %s\n", dev_pathname);
> +
> +	if (rte_vhost_driver_register(dev_pathname, 0) != 0) {
> +		fprintf(stderr, "socket %s already exists\n", dev_pathname);
> +		return NULL;
> +	}
> +
> +	ret = rte_vhost_driver_set_features(dev_pathname,
> VIRTIO_SCSI_FEATURES);
> +	if (ret) {
> +		fprintf(stderr, "Set vhost driver features failed\n");
> +		return NULL;
> +	}
> +
> +	ctrlr = rte_zmalloc(NULL, sizeof(*ctrlr), RTE_CACHE_LINE_SIZE);
> +	if (!ctrlr)
> +		return NULL;
> +
> +	ctrlr->name = strdup(ctrlr_name);

name is never used  and also never free.

> +
> +	rte_vhost_driver_callback_register(dev_pathname,
> +					   &vhost_scsi_device_ops);
> +
> +	return ctrlr;
> +}
> +
> +static void
> +signal_handler(__rte_unused int signum)
> +{

Some message would be good to inform about successful exit.

> +	if (access(dev_pathname, F_OK) == 0)
> +		unlink(dev_pathname);
> +	exit(0);
> +}
> +

> diff --git a/examples/vhost_scsi/vhost_scsi.h b/examples/vhost_scsi/vhost_scsi.h
> new file mode 100644
> index 0000000..b5340cc
> --- /dev/null
> +++ b/examples/vhost_scsi/vhost_scsi.h
> @@ -0,0 +1,250 @@

Do we need this file at all? I think it can got to .c file

> +
> +#include <rte_vhost.h>
> +
> +static inline uint16_t
> +from_be16(const void *ptr)
> +{
> +	const uint8_t *tmp = (const uint8_t *)ptr;
> +
> +	return (((uint16_t)tmp[0] << 8) | tmp[1]);
> +}
> +

Why implementing this instead of using existing macros from rte_byteorder.h?

> +
> +struct vaddr_region {
> +	void *vaddr;
> +	uint64_t len;
> +};

I don't see any usage of this struct.

> +
> +struct vhost_scsi_queue {
> +	struct rte_vhost_vring vq;
> +	uint16_t last_avail_idx;
> +	uint16_t last_used_idx;
> +};
> +
> +struct vhost_block_dev {
> +	/** ID for vhost library. */
> +	int vid;

Don't think this is right place for vid. As mentioned, pointer to struct vhost_scsi_ctrlr would be better here.

> +	/** Queues for the block device */
> +	struct vhost_scsi_queue queues[8];

You define 8 queues here but in vhost_scsi.c NUM_OF_SCSI_QUEUES is 3.
Maybe move definition of NUM_OF_SCSI_QUEUES to .h file and use it here instead of '8'

> +	/** Unique name for this block device. */
> +	char name[64];
> +
> +	/** Unique product name for this kind of block device. */
> +	char product_name[256];
> +
> +	/** Size in bytes of a logical block for the backend */
> +	uint32_t blocklen;
> +
> +	/** Number of blocks */
> +	uint64_t blockcnt;
> +
> +	/** write cache enabled, not used at the moment */
> +	int write_cache;

So can be removed.

> +
> +	/** use memory as disk storage space */
> +	uint8_t *data;
> +};
> +

Thanks
Pawel
  

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index b4424ea..b1cc956 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -434,6 +434,8 @@  F: lib/librte_vhost/
 F: doc/guides/prog_guide/vhost_lib.rst
 F: examples/vhost/
 F: doc/guides/sample_app_ug/vhost.rst
+F: examples/vhost_scsi/
+F: doc/guides/sample_app_ug/vhost_scsi.rst
 
 Vhost PMD
 M: Tetsuya Mukawa <mtetsuyah@gmail.com>
diff --git a/doc/guides/sample_app_ug/vhost_scsi.rst b/doc/guides/sample_app_ug/vhost_scsi.rst
new file mode 100644
index 0000000..be45017
--- /dev/null
+++ b/doc/guides/sample_app_ug/vhost_scsi.rst
@@ -0,0 +1,110 @@ 
+
+..  BSD LICENSE
+    Copyright(c) 2010-2017 Intel Corporation. All rights reserved.
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+
+    * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+    * Neither the name of Intel Corporation nor the names of its
+    contributors may be used to endorse or promote products derived
+    from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+Vhost_scsi Sample Application
+========================
+
+The vhost_scsi sample application implemented a simple SCSI block device,
+which used as the  backend of Qemu vhost-user-scsi device. Users can extend
+the exist example to use other type of block device(e.g. AIO) besides
+memory based block device. Similar with vhost-user-net device, the sample
+application used domain socket to communicate with Qemu, and the virtio
+ring was processed by vhost_scsi sample application.
+
+Testing steps
+-------------
+
+This section shows the steps how to start a VM with the block device as
+fast data path for critical application.
+
+Build
+~~~~~
+
+Follow the *Getting Started Guide for Linux* on generic info about
+environment setup and building DPDK from source.
+
+In this example, you need build DPDK both on the host and inside guest.
+Also, you need build this example.
+
+.. code-block:: console
+
+    export RTE_SDK=/path/to/dpdk_source
+    export RTE_TARGET=x86_64-native-linuxapp-gcc
+
+    cd ${RTE_SDK}/examples/vhost_scsi
+    make
+
+
+Start the vhost_scsi example
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: console
+
+        ./vhost_scsi -m 1024
+
+.. _vhost_scsi_app_run_vm:
+
+Start the VM
+~~~~~~~~~~~~
+
+.. code-block:: console
+
+    qemu-system-x86_64 -machine accel=kvm \
+        -m $mem -object memory-backend-file,id=mem,size=$mem,\
+        mem-path=/dev/hugepages,share=on -numa node,memdev=mem \
+        -drive file=os.img,if=none,id=disk \
+        -device ide-hd,drive=disk,bootindex=0 \
+        -chardev socket,id=char0,path=/tmp/vhost.socket \
+        -device vhost-user-scsi-pci,chardev=char0,bootindex=2 \
+        ...
+
+.. note::
+    You must check whether your Qemu can support "vhost-user-scsi" or not,
+    Qemu v2.10 or newer version is required.
+
+Vhost_scsi Common Issues
+-------------
+
+* vhost_scsi can not start with block size 512 Bytes:
+
+  Currently DPDK vhost library was designed for NET device(althrough the APIs
+  are generic now), for 512 Bytes block device, Qemu BIOS(x86 BIOS Enhanced
+  Disk Device) will enumerate all block device and do some IOs to those block
+  devices with 512 Bytes sector size. DPDK vhost library can not process such
+  scenarios(both BIOS and OS will enumerate the block device), so as a
+  workaround, the vhost_scsi example application hardcoded the block size
+  with 4096 Bytes.
+
+* vhost_scsi can only support the block device as fast data disk(non OS image):
+
+  Make sure ``bootindex=2`` Qemu option is given to vhost-user-scsi-pci device.
+
diff --git a/examples/Makefile b/examples/Makefile
index c0e9c3b..05986b6 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -88,7 +88,7 @@  ifeq ($(CONFIG_RTE_LIBRTE_HASH),y)
 DIRS-$(CONFIG_RTE_LIBRTE_VHOST) += tep_termination
 endif
 DIRS-$(CONFIG_RTE_LIBRTE_TIMER) += timer
-DIRS-$(CONFIG_RTE_LIBRTE_VHOST) += vhost
+DIRS-$(CONFIG_RTE_LIBRTE_VHOST) += vhost vhost_scsi
 DIRS-$(CONFIG_RTE_LIBRTE_XEN_DOM0) += vhost_xen
 DIRS-y += vmdq
 DIRS-y += vmdq_dcb
diff --git a/examples/vhost_scsi/Makefile b/examples/vhost_scsi/Makefile
new file mode 100644
index 0000000..0306a6a
--- /dev/null
+++ b/examples/vhost_scsi/Makefile
@@ -0,0 +1,59 @@ 
+#   BSD LICENSE
+#
+#   Copyright(c) 2010-2017 Intel Corporation. All rights reserved.
+#   All rights reserved.
+#
+#   Redistribution and use in source and binary forms, with or without
+#   modification, are permitted provided that the following conditions
+#   are met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in
+#       the documentation and/or other materials provided with the
+#       distribution.
+#     * Neither the name of Intel Corporation nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+ifeq ($(RTE_SDK),)
+$(error "Please define RTE_SDK environment variable")
+endif
+
+# Default target, can be overridden by command line or environment
+RTE_TARGET ?= x86_64-native-linuxapp-gcc
+
+include $(RTE_SDK)/mk/rte.vars.mk
+
+ifneq ($(CONFIG_RTE_EXEC_ENV),"linuxapp")
+$(info This application can only operate in a linuxapp environment, \
+please change the definition of the RTE_TARGET environment variable)
+all:
+else
+
+# binary name
+APP = vhost-scsi
+
+# all source are stored in SRCS-y
+SRCS-y := scsi.c vhost_scsi.c
+
+CFLAGS += -O2 -D_FILE_OFFSET_BITS=64
+CFLAGS += $(WERROR_FLAGS)
+CFLAGS += -D_GNU_SOURCE
+
+include $(RTE_SDK)/mk/rte.extapp.mk
+
+endif
diff --git a/examples/vhost_scsi/scsi.c b/examples/vhost_scsi/scsi.c
new file mode 100644
index 0000000..08dfe61
--- /dev/null
+++ b/examples/vhost_scsi/scsi.c
@@ -0,0 +1,507 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2010-2017 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <assert.h>
+#include <ctype.h>
+#include <string.h>
+#include <stddef.h>
+
+#include <rte_atomic.h>
+#include <rte_cycles.h>
+#include <rte_log.h>
+#include <rte_malloc.h>
+
+#include "vhost_scsi.h"
+#include "scsi_spec.h"
+
+#define INQ_OFFSET(field) (offsetof(struct scsi_cdb_inquiry_data, field) + \
+			  sizeof(((struct scsi_cdb_inquiry_data *)0x0)->field))
+
+static void
+vhost_strcpy_pad(void *dst, const char *src, size_t size, int pad)
+{
+	size_t len;
+
+	len = strlen(src);
+	if (len < size) {
+		memcpy(dst, src, len);
+		memset((char *)dst + len, pad, size - len);
+	} else {
+		memcpy(dst, src, size);
+	}
+}
+
+static int
+vhost_hex2bin(char ch)
+{
+	if ((ch >= '0') && (ch <= '9'))
+		return ch - '0';
+	ch = tolower(ch);
+	if ((ch >= 'a') && (ch <= 'f'))
+		return ch - 'a' + 10;
+	return (int)ch;
+}
+
+static void
+vhost_bdev_scsi_set_local_naa(char *name, uint8_t *buf)
+{
+	int i, value, count = 0;
+	uint64_t naa, local_value;
+
+	for (i = 0; (i < 16) && (name[i] != '\0'); i++) {
+		value = vhost_hex2bin(name[i]);
+		if (i % 2)
+			buf[count++] |= value << 4;
+		else
+			buf[count] = value;
+	}
+	/* NAA locally assigned filed */
+	naa = 0x3;
+	local_value = *(uint64_t *)buf;
+	local_value = (naa << 60) | (local_value >> 4);
+	to_be64((void *)buf, local_value);
+}
+
+static void
+scsi_task_build_sense_data(struct vhost_scsi_task *task, int sk,
+			   int asc, int ascq)
+{
+	uint8_t *cp;
+	int resp_code;
+
+	resp_code = 0x70; /* Current + Fixed format */
+
+	/* Sense Data */
+	cp = (uint8_t *)task->resp->sense;
+
+	/* VALID(7) RESPONSE CODE(6-0) */
+	cp[0] = 0x80 | resp_code;
+	/* Obsolete */
+	cp[1] = 0;
+	/* FILEMARK(7) EOM(6) ILI(5) SENSE KEY(3-0) */
+	cp[2] = sk & 0xf;
+	/* INFORMATION */
+	memset(&cp[3], 0, 4);
+
+	/* ADDITIONAL SENSE LENGTH */
+	cp[7] = 10;
+
+	/* COMMAND-SPECIFIC INFORMATION */
+	memset(&cp[8], 0, 4);
+	/* ADDITIONAL SENSE CODE */
+	cp[12] = asc;
+	/* ADDITIONAL SENSE CODE QUALIFIER */
+	cp[13] = ascq;
+	/* FIELD REPLACEABLE UNIT CODE */
+	cp[14] = 0;
+
+	/* SKSV(7) SENSE KEY SPECIFIC(6-0,7-0,7-0) */
+	cp[15] = 0;
+	cp[16] = 0;
+	cp[17] = 0;
+
+	/* SenseLength */
+	task->resp->sense_len = 18;
+}
+
+static void
+scsi_task_set_status(struct vhost_scsi_task *task, int sc, int sk,
+		     int asc, int ascq)
+{
+	if (sc == SCSI_STATUS_CHECK_CONDITION)
+		scsi_task_build_sense_data(task, sk, asc, ascq);
+	task->resp->status = sc;
+}
+
+static int
+vhost_bdev_scsi_inquiry_command(struct vhost_block_dev *bdev,
+				struct vhost_scsi_task *task)
+{
+	int hlen = 0;
+	uint32_t alloc_len = 0;
+	uint16_t len = 0;
+	int pc;
+	int pd;
+	int evpd;
+	int i;
+	uint8_t *buf;
+	struct scsi_cdb_inquiry *inq;
+
+	inq = (struct scsi_cdb_inquiry *)task->req->cdb;
+
+	assert(task->iovs_cnt == 1);
+
+	/* At least 36Bytes for inquiry command */
+	if (task->data_len < 0x24)
+		goto inq_error;
+
+	pd = SPC_PERIPHERAL_DEVICE_TYPE_DISK;
+	pc = inq->page_code;
+	evpd = inq->evpd & 0x1;
+
+	if (!evpd && pc)
+		goto inq_error;
+
+	if (evpd) {
+		struct scsi_vpd_page *vpage = (struct scsi_vpd_page *)
+					      task->iovs[0].iov_base;
+
+		/* PERIPHERAL QUALIFIER(7-5) PERIPHERAL DEVICE TYPE(4-0) */
+		vpage->peripheral = pd;
+		/* PAGE CODE */
+		vpage->page_code = pc;
+
+		switch (pc) {
+		case SPC_VPD_SUPPORTED_VPD_PAGES:
+			hlen = 4;
+			vpage->params[0] = SPC_VPD_SUPPORTED_VPD_PAGES;
+			vpage->params[1] = SPC_VPD_UNIT_SERIAL_NUMBER;
+			vpage->params[2] = SPC_VPD_DEVICE_IDENTIFICATION;
+			len = 3;
+			/* PAGE LENGTH */
+			to_be16(vpage->alloc_len, len);
+			break;
+		case SPC_VPD_UNIT_SERIAL_NUMBER:
+			hlen = 4;
+			strncpy((char *)vpage->params, bdev->name, 32);
+			to_be16(vpage->alloc_len, 32);
+			break;
+		case SPC_VPD_DEVICE_IDENTIFICATION:
+			buf = vpage->params;
+			struct scsi_desig_desc *desig;
+
+			hlen = 4;
+			/* NAA designator */
+			desig = (struct scsi_desig_desc *)buf;
+			desig->code_set = SPC_VPD_CODE_SET_BINARY;
+			desig->protocol_id = SPC_PROTOCOL_IDENTIFIER_ISCSI;
+			desig->type = SPC_VPD_IDENTIFIER_TYPE_NAA;
+			desig->association = SPC_VPD_ASSOCIATION_LOGICAL_UNIT;
+			desig->reserved0 = 0;
+			desig->piv = 1;
+			desig->reserved1 = 0;
+			desig->len = 8;
+			vhost_bdev_scsi_set_local_naa(bdev->name, desig->desig);
+			len = sizeof(struct scsi_desig_desc) + 8;
+
+			buf += sizeof(struct scsi_desig_desc) + desig->len;
+
+			/* T10 Vendor ID designator */
+			desig = (struct scsi_desig_desc *)buf;
+			desig->code_set = SPC_VPD_CODE_SET_ASCII;
+			desig->protocol_id = SPC_PROTOCOL_IDENTIFIER_ISCSI;
+			desig->type = SPC_VPD_IDENTIFIER_TYPE_T10_VENDOR_ID;
+			desig->association = SPC_VPD_ASSOCIATION_LOGICAL_UNIT;
+			desig->reserved0 = 0;
+			desig->piv = 1;
+			desig->reserved1 = 0;
+			desig->len = 8 + 16 + 32;
+			strncpy((char *)desig->desig, "INTEL", 8);
+			vhost_strcpy_pad((char *)&desig->desig[8],
+					 bdev->product_name, 16, ' ');
+			strncpy((char *)&desig->desig[24], bdev->name, 32);
+			len += sizeof(struct scsi_desig_desc) + 8 + 16 + 32;
+
+			buf += sizeof(struct scsi_desig_desc) + desig->len;
+
+			/* SCSI Device Name designator */
+			desig = (struct scsi_desig_desc *)buf;
+			desig->code_set = SPC_VPD_CODE_SET_UTF8;
+			desig->protocol_id = SPC_PROTOCOL_IDENTIFIER_ISCSI;
+			desig->type = SPC_VPD_IDENTIFIER_TYPE_SCSI_NAME;
+			desig->association = SPC_VPD_ASSOCIATION_TARGET_DEVICE;
+			desig->reserved0 = 0;
+			desig->piv = 1;
+			desig->reserved1 = 0;
+			desig->len = snprintf((char *)desig->desig,
+					      255, "%s", bdev->name);
+			len += sizeof(struct scsi_desig_desc) + desig->len;
+
+			buf += sizeof(struct scsi_desig_desc) + desig->len;
+			to_be16(vpage->alloc_len, len);
+			break;
+		default:
+			goto inq_error;
+		}
+
+	} else {
+		struct scsi_cdb_inquiry_data *inqdata =
+			(struct scsi_cdb_inquiry_data *)task->iovs[0].iov_base;
+		/* Standard INQUIRY data */
+		/* PERIPHERAL QUALIFIER(7-5) PERIPHERAL DEVICE TYPE(4-0) */
+		inqdata->peripheral = pd;
+
+		/* RMB(7) */
+		inqdata->rmb = 0;
+
+		/* VERSION */
+		/* See SPC3/SBC2/MMC4/SAM2 for more details */
+		inqdata->version = SPC_VERSION_SPC3;
+
+		/* NORMACA(5) HISUP(4) RESPONSE DATA FORMAT(3-0) */
+		/* format 2 */ /* hierarchical support */
+		inqdata->response = 2 | 1 << 4;
+
+		hlen = 5;
+
+		/* SCCS(7) ACC(6) TPGS(5-4) 3PC(3) PROTECT(0) */
+		/* Not support TPGS */
+		inqdata->flags = 0;
+
+		/* MULTIP */
+		inqdata->flags2 = 0x10;
+
+		/* WBUS16(5) SYNC(4) LINKED(3) CMDQUE(1) VS(0) */
+		/* CMDQUE */
+		inqdata->flags3 = 0x2;
+
+		/* T10 VENDOR IDENTIFICATION */
+		strncpy((char *)inqdata->t10_vendor_id, "INTEL", 8);
+
+		/* PRODUCT IDENTIFICATION */
+		strncpy((char *)inqdata->product_id, bdev->product_name, 16);
+
+		/* PRODUCT REVISION LEVEL */
+		strncpy((char *)inqdata->product_rev, "0001", 4);
+
+		/* Standard inquiry data ends here. Only populate
+		 * remaining fields if alloc_len indicates enough
+		 * space to hold it.
+		 */
+		len = INQ_OFFSET(product_rev) - 5;
+
+		if (alloc_len >= INQ_OFFSET(vendor)) {
+			/* Vendor specific */
+			memset(inqdata->vendor, 0x20, 20);
+			len += sizeof(inqdata->vendor);
+		}
+
+		if (alloc_len >= INQ_OFFSET(ius)) {
+			/* CLOCKING(3-2) QAS(1) IUS(0) */
+			inqdata->ius = 0;
+			len += sizeof(inqdata->ius);
+		}
+
+		if (alloc_len >= INQ_OFFSET(reserved)) {
+			/* Reserved */
+			inqdata->reserved = 0;
+			len += sizeof(inqdata->reserved);
+		}
+
+		/* VERSION DESCRIPTOR 1-8 */
+		if (alloc_len >= INQ_OFFSET(reserved) + 2) {
+			to_be16(&inqdata->desc[0], 0x0960);
+			len += 2;
+		}
+
+		if (alloc_len >= INQ_OFFSET(reserved) + 4) {
+			/* SPC-3 (no version claimed) */
+			to_be16(&inqdata->desc[2], 0x0300);
+			len += 2;
+		}
+
+		if (alloc_len >= INQ_OFFSET(reserved) + 6) {
+			/* SBC-2 (no version claimed) */
+			to_be16(&inqdata->desc[4], 0x320);
+			len += 2;
+		}
+
+		if (alloc_len >= INQ_OFFSET(reserved) + 8) {
+			/* SAM-2 (no version claimed) */
+			to_be16(&inqdata->desc[6], 0x0040);
+			len += 2;
+		}
+
+		if (alloc_len > INQ_OFFSET(reserved) + 8) {
+			i = alloc_len - (INQ_OFFSET(reserved) + 8);
+			if (i > 30)
+				i = 30;
+			memset(&inqdata->desc[8], 0, i);
+			len += i;
+		}
+
+		/* ADDITIONAL LENGTH */
+		inqdata->add_len = len;
+	}
+
+	/* STATUS GOOD */
+	scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
+	return hlen + len;
+
+inq_error:
+	scsi_task_set_status(task, SCSI_STATUS_CHECK_CONDITION,
+				     SCSI_SENSE_ILLEGAL_REQUEST,
+				     SCSI_ASC_INVALID_FIELD_IN_CDB,
+				     SCSI_ASCQ_CAUSE_NOT_REPORTABLE);
+	return 0;
+}
+
+static int
+vhost_bdev_scsi_readwrite(struct vhost_block_dev *bdev,
+			  struct vhost_scsi_task *task,
+			  uint64_t lba, __rte_unused uint32_t xfer_len)
+{
+	uint32_t i;
+	uint64_t offset;
+	uint32_t nbytes = 0;
+
+	offset = lba * bdev->blocklen;
+
+	for (i = 0; i < task->iovs_cnt; i++) {
+		if (task->dxfer_dir == SCSI_DIR_TO_DEV)
+			memcpy(bdev->data + offset, task->iovs[i].iov_base,
+			       task->iovs[i].iov_len);
+		else
+			memcpy(task->iovs[i].iov_base, bdev->data + offset,
+			       task->iovs[i].iov_len);
+		offset += task->iovs[i].iov_len;
+		nbytes += task->iovs[i].iov_len;
+	}
+
+	return nbytes;
+}
+
+static int
+vhost_bdev_scsi_process_block(struct vhost_block_dev *bdev,
+			      struct vhost_scsi_task *task)
+{
+	uint64_t lba;
+	uint32_t xfer_len;
+	uint8_t *cdb = (uint8_t *)task->req->cdb;
+
+	switch (cdb[0]) {
+	case SBC_READ_6:
+	case SBC_WRITE_6:
+		lba = (uint64_t)cdb[1] << 16;
+		lba |= (uint64_t)cdb[2] << 8;
+		lba |= (uint64_t)cdb[3];
+		xfer_len = cdb[4];
+		if (xfer_len == 0)
+			xfer_len = 256;
+		return vhost_bdev_scsi_readwrite(bdev, task, lba, xfer_len);
+
+	case SBC_READ_10:
+	case SBC_WRITE_10:
+		lba = from_be32(&cdb[2]);
+		xfer_len = from_be16(&cdb[7]);
+		return vhost_bdev_scsi_readwrite(bdev, task, lba, xfer_len);
+
+	case SBC_READ_12:
+	case SBC_WRITE_12:
+		lba = from_be32(&cdb[2]);
+		xfer_len = from_be32(&cdb[6]);
+		return vhost_bdev_scsi_readwrite(bdev, task, lba, xfer_len);
+
+	case SBC_READ_16:
+	case SBC_WRITE_16:
+		lba = from_be64(&cdb[2]);
+		xfer_len = from_be32(&cdb[10]);
+		return vhost_bdev_scsi_readwrite(bdev, task, lba, xfer_len);
+
+	case SBC_READ_CAPACITY_10: {
+		uint8_t buffer[8];
+
+		if (bdev->blockcnt - 1 > 0xffffffffULL)
+			memset(buffer, 0xff, 4);
+		else
+			to_be32(buffer, bdev->blockcnt - 1);
+		to_be32(&buffer[4], bdev->blocklen);
+		memcpy(task->iovs[0].iov_base, buffer, sizeof(buffer));
+		task->resp->status = SCSI_STATUS_GOOD;
+		return sizeof(buffer);
+	}
+
+	case SBC_SYNCHRONIZE_CACHE_10:
+	case SBC_SYNCHRONIZE_CACHE_16:
+		task->resp->status = SCSI_STATUS_GOOD;
+		return 0;
+	}
+
+	scsi_task_set_status(task, SCSI_STATUS_CHECK_CONDITION,
+			     SCSI_SENSE_ILLEGAL_REQUEST,
+			     SCSI_ASC_INVALID_FIELD_IN_CDB,
+			     SCSI_ASCQ_CAUSE_NOT_REPORTABLE);
+	return 0;
+}
+
+int
+vhost_bdev_process_scsi_commands(struct vhost_block_dev *bdev,
+				 struct vhost_scsi_task *task)
+{
+	int len;
+	uint8_t *data;
+	uint64_t fmt_lun = 0;
+	const uint8_t *lun;
+	uint8_t *cdb = (uint8_t *)task->req->cdb;
+
+	lun = (const uint8_t *)task->req->lun;
+	/* only 1 LUN supported */
+	if (lun[0] != 1 || lun[1] >= 1)
+		return -1;
+
+	switch (cdb[0]) {
+	case SPC_INQUIRY:
+		len = vhost_bdev_scsi_inquiry_command(bdev, task);
+		task->data_len = len;
+		break;
+	case SPC_REPORT_LUNS:
+		data = (uint8_t *)task->iovs[0].iov_base;
+		fmt_lun |= (0x0ULL & 0x00ffULL) << 48;
+		to_be64((void *)&data[8], fmt_lun);
+		to_be32((void *)data, 8);
+		task->data_len = 16;
+		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
+		break;
+	case SPC_MODE_SELECT_6:
+	case SPC_MODE_SELECT_10:
+		/* TODO: Add SCSI Commands support */
+		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
+		break;
+	case SPC_MODE_SENSE_6:
+	case SPC_MODE_SENSE_10:
+		/* TODO: Add SCSI Commands support */
+		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
+		break;
+	case SPC_TEST_UNIT_READY:
+		scsi_task_set_status(task, SCSI_STATUS_GOOD, 0, 0, 0);
+		break;
+	default:
+		len = vhost_bdev_scsi_process_block(bdev, task);
+		task->data_len = len;
+	}
+
+	return 0;
+}
diff --git a/examples/vhost_scsi/scsi_spec.h b/examples/vhost_scsi/scsi_spec.h
new file mode 100644
index 0000000..0474d92
--- /dev/null
+++ b/examples/vhost_scsi/scsi_spec.h
@@ -0,0 +1,488 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright (c) Intel Corporation.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _SCSI_SPEC_H
+#define _SCSI_SPEC_H
+
+#include <stdint.h>
+
+enum scsi_group_code {
+	SCSI_6BYTE_CMD = 0x00,
+	SCSI_10BYTE_CMD = 0x20,
+	SCSI_10BYTE_CMD2 = 0x40,
+	SCSI_16BYTE_CMD = 0x80,
+	SCSI_12BYTE_CMD = 0xa0,
+};
+
+#define SCSI_GROUP_MASK	0xe0
+#define SCSI_OPCODE_MASK	0x1f
+
+enum scsi_status {
+	SCSI_STATUS_GOOD = 0x00,
+	SCSI_STATUS_CHECK_CONDITION = 0x02,
+	SCSI_STATUS_CONDITION_MET = 0x04,
+	SCSI_STATUS_BUSY = 0x08,
+	SCSI_STATUS_INTERMEDIATE = 0x10,
+	SCSI_STATUS_INTERMEDIATE_CONDITION_MET = 0x14,
+	SCSI_STATUS_RESERVATION_CONFLICT = 0x18,
+	SCSI_STATUS_Obsolete = 0x22,
+	SCSI_STATUS_TASK_SET_FULL = 0x28,
+	SCSI_STATUS_ACA_ACTIVE = 0x30,
+	SCSI_STATUS_TASK_ABORTED = 0x40,
+};
+
+enum scsi_sense {
+	SCSI_SENSE_NO_SENSE = 0x00,
+	SCSI_SENSE_RECOVERED_ERROR = 0x01,
+	SCSI_SENSE_NOT_READY = 0x02,
+	SCSI_SENSE_MEDIUM_ERROR = 0x03,
+	SCSI_SENSE_HARDWARE_ERROR = 0x04,
+	SCSI_SENSE_ILLEGAL_REQUEST = 0x05,
+	SCSI_SENSE_UNIT_ATTENTION = 0x06,
+	SCSI_SENSE_DATA_PROTECT = 0x07,
+	SCSI_SENSE_BLANK_CHECK = 0x08,
+	SCSI_SENSE_VENDOR_SPECIFIC = 0x09,
+	SCSI_SENSE_COPY_ABORTED = 0x0a,
+	SCSI_SENSE_ABORTED_COMMAND = 0x0b,
+	SCSI_SENSE_VOLUME_OVERFLOW = 0x0d,
+	SCSI_SENSE_MISCOMPARE = 0x0e,
+};
+
+enum scsi_asc {
+	SCSI_ASC_NO_ADDITIONAL_SENSE = 0x00,
+	SCSI_ASC_PERIPHERAL_DEVICE_WRITE_FAULT = 0x03,
+	SCSI_ASC_LOGICAL_UNIT_NOT_READY = 0x04,
+	SCSI_ASC_WARNING = 0x0b,
+	SCSI_ASC_LOGICAL_BLOCK_GUARD_CHECK_FAILED = 0x10,
+	SCSI_ASC_LOGICAL_BLOCK_APP_TAG_CHECK_FAILED = 0x10,
+	SCSI_ASC_LOGICAL_BLOCK_REF_TAG_CHECK_FAILED = 0x10,
+	SCSI_ASC_UNRECOVERED_READ_ERROR = 0x11,
+	SCSI_ASC_MISCOMPARE_DURING_VERIFY_OPERATION = 0x1d,
+	SCSI_ASC_INVALID_COMMAND_OPERATION_CODE = 0x20,
+	SCSI_ASC_ACCESS_DENIED = 0x20,
+	SCSI_ASC_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE = 0x21,
+	SCSI_ASC_INVALID_FIELD_IN_CDB = 0x24,
+	SCSI_ASC_LOGICAL_UNIT_NOT_SUPPORTED = 0x25,
+	SCSI_ASC_WRITE_PROTECTED = 0x27,
+	SCSI_ASC_FORMAT_COMMAND_FAILED = 0x31,
+	SCSI_ASC_INTERNAL_TARGET_FAILURE = 0x44,
+};
+
+enum scsi_ascq {
+	SCSI_ASCQ_CAUSE_NOT_REPORTABLE = 0x00,
+	SCSI_ASCQ_BECOMING_READY = 0x01,
+	SCSI_ASCQ_FORMAT_COMMAND_FAILED = 0x01,
+	SCSI_ASCQ_LOGICAL_BLOCK_GUARD_CHECK_FAILED = 0x01,
+	SCSI_ASCQ_LOGICAL_BLOCK_APP_TAG_CHECK_FAILED = 0x02,
+	SCSI_ASCQ_NO_ACCESS_RIGHTS = 0x02,
+	SCSI_ASCQ_LOGICAL_BLOCK_REF_TAG_CHECK_FAILED = 0x03,
+	SCSI_ASCQ_POWER_LOSS_EXPECTED = 0x08,
+	SCSI_ASCQ_INVALID_LU_IDENTIFIER = 0x09,
+};
+
+enum spc_opcode {
+	/* SPC3 related */
+	SPC_ACCESS_CONTROL_IN = 0x86,
+	SPC_ACCESS_CONTROL_OUT = 0x87,
+	SPC_EXTENDED_COPY = 0x83,
+	SPC_INQUIRY = 0x12,
+	SPC_LOG_SELECT = 0x4c,
+	SPC_LOG_SENSE = 0x4d,
+	SPC_MODE_SELECT_6 = 0x15,
+	SPC_MODE_SELECT_10 = 0x55,
+	SPC_MODE_SENSE_6 = 0x1a,
+	SPC_MODE_SENSE_10 = 0x5a,
+	SPC_PERSISTENT_RESERVE_IN = 0x5e,
+	SPC_PERSISTENT_RESERVE_OUT = 0x5f,
+	SPC_PREVENT_ALLOW_MEDIUM_REMOVAL = 0x1e,
+	SPC_READ_ATTRIBUTE = 0x8c,
+	SPC_READ_BUFFER = 0x3c,
+	SPC_RECEIVE_COPY_RESULTS = 0x84,
+	SPC_RECEIVE_DIAGNOSTIC_RESULTS = 0x1c,
+	SPC_REPORT_LUNS = 0xa0,
+	SPC_REQUEST_SENSE = 0x03,
+	SPC_SEND_DIAGNOSTIC = 0x1d,
+	SPC_TEST_UNIT_READY = 0x00,
+	SPC_WRITE_ATTRIBUTE = 0x8d,
+	SPC_WRITE_BUFFER = 0x3b,
+
+	SPC_SERVICE_ACTION_IN_12 = 0xab,
+	SPC_SERVICE_ACTION_OUT_12 = 0xa9,
+	SPC_SERVICE_ACTION_IN_16 = 0x9e,
+	SPC_SERVICE_ACTION_OUT_16 = 0x9f,
+
+	SPC_VARIABLE_LENGTH = 0x7f,
+
+	SPC_MO_CHANGE_ALIASES = 0x0b,
+	SPC_MO_SET_DEVICE_IDENTIFIER = 0x06,
+	SPC_MO_SET_PRIORITY = 0x0e,
+	SPC_MO_SET_TARGET_PORT_GROUPS = 0x0a,
+	SPC_MO_SET_TIMESTAMP = 0x0f,
+	SPC_MI_REPORT_ALIASES = 0x0b,
+	SPC_MI_REPORT_DEVICE_IDENTIFIER = 0x05,
+	SPC_MI_REPORT_PRIORITY = 0x0e,
+	SPC_MI_REPORT_SUPPORTED_OPERATION_CODES = 0x0c,
+	SPC_MI_REPORT_SUPPORTED_TASK_MANAGEMENT_FUNCTIONS = 0x0d,
+	SPC_MI_REPORT_TARGET_PORT_GROUPS = 0x0a,
+	SPC_MI_REPORT_TIMESTAMP = 0x0f,
+
+	/* SPC2 related (Obsolete) */
+	SPC2_RELEASE_6 = 0x17,
+	SPC2_RELEASE_10 = 0x57,
+	SPC2_RESERVE_6 = 0x16,
+	SPC2_RESERVE_10 = 0x56,
+};
+
+enum scc_opcode {
+	SCC_MAINTENANCE_IN = 0xa3,
+	SCC_MAINTENANCE_OUT = 0xa4,
+};
+
+enum sbc_opcode {
+	SBC_COMPARE_AND_WRITE = 0x89,
+	SBC_FORMAT_UNIT = 0x04,
+	SBC_GET_LBA_STATUS = 0x0012009e,
+	SBC_ORWRITE_16 = 0x8b,
+	SBC_PRE_FETCH_10 = 0x34,
+	SBC_PRE_FETCH_16 = 0x90,
+	SBC_READ_6 = 0x08,
+	SBC_READ_10 = 0x28,
+	SBC_READ_12 = 0xa8,
+	SBC_READ_16 = 0x88,
+	SBC_READ_ATTRIBUTE = 0x8c,
+	SBC_READ_BUFFER = 0x3c,
+	SBC_READ_CAPACITY_10 = 0x25,
+	SBC_READ_DEFECT_DATA_10 = 0x37,
+	SBC_READ_DEFECT_DATA_12 = 0xb7,
+	SBC_READ_LONG_10 = 0x3e,
+	SBC_REASSIGN_BLOCKS = 0x07,
+	SBC_SANITIZE = 0x48,
+	SBC_START_STOP_UNIT = 0x1b,
+	SBC_SYNCHRONIZE_CACHE_10 = 0x35,
+	SBC_SYNCHRONIZE_CACHE_16 = 0x91,
+	SBC_UNMAP = 0x42,
+	SBC_VERIFY_10 = 0x2f,
+	SBC_VERIFY_12 = 0xaf,
+	SBC_VERIFY_16 = 0x8f,
+	SBC_WRITE_6 = 0x0a,
+	SBC_WRITE_10 = 0x2a,
+	SBC_WRITE_12 = 0xaa,
+	SBC_WRITE_16 = 0x8a,
+	SBC_WRITE_AND_VERIFY_10 = 0x2e,
+	SBC_WRITE_AND_VERIFY_12 = 0xae,
+	SBC_WRITE_AND_VERIFY_16 = 0x8e,
+	SBC_WRITE_LONG_10 = 0x3f,
+	SBC_WRITE_SAME_10 = 0x41,
+	SBC_WRITE_SAME_16 = 0x93,
+	SBC_XDREAD_10 = 0x52,
+	SBC_XDWRITE_10 = 0x50,
+	SBC_XDWRITEREAD_10 = 0x53,
+	SBC_XPWRITE_10 = 0x51,
+
+	SBC_SAI_READ_CAPACITY_16 = 0x10,
+	SBC_SAI_READ_LONG_16 = 0x11,
+	SBC_SAO_WRITE_LONG_16 = 0x11,
+
+	SBC_VL_READ_32 = 0x0009,
+	SBC_VL_VERIFY_32 = 0x000a,
+	SBC_VL_WRITE_32 = 0x000b,
+	SBC_VL_WRITE_AND_VERIFY_32 = 0x000c,
+	SBC_VL_WRITE_SAME_32 = 0x000d,
+	SBC_VL_XDREAD_32 = 0x0003,
+	SBC_VL_XDWRITE_32 = 0x0004,
+	SBC_VL_XDWRITEREAD_32 = 0x0007,
+	SBC_VL_XPWRITE_32 = 0x0006,
+};
+
+enum mmc_opcode {
+	/* MMC6 */
+	MMC_READ_DISC_STRUCTURE = 0xad,
+
+	/* MMC4 */
+	MMC_BLANK = 0xa1,
+	MMC_CLOSE_TRACK_SESSION = 0x5b,
+	MMC_ERASE_10 = 0x2c,
+	MMC_FORMAT_UNIT = 0x04,
+	MMC_GET_CONFIGURATION = 0x46,
+	MMC_GET_EVENT_STATUS_NOTIFICATION = 0x4a,
+	MMC_GET_PERFORMANCE = 0xac,
+	MMC_INQUIRY = 0x12,
+	MMC_LOAD_UNLOAD_MEDIUM = 0xa6,
+	MMC_MECHANISM_STATUS = 0xbd,
+	MMC_MODE_SELECT_10 = 0x55,
+	MMC_MODE_SENSE_10 = 0x5a,
+	MMC_PAUSE_RESUME = 0x4b,
+	MMC_PLAY_AUDIO_10 = 0x45,
+	MMC_PLAY_AUDIO_12 = 0xa5,
+	MMC_PLAY_AUDIO_MSF = 0x47,
+	MMC_PREVENT_ALLOW_MEDIUM_REMOVAL = 0x1e,
+	MMC_READ_10 = 0x28,
+	MMC_READ_12 = 0xa8,
+	MMC_READ_BUFFER = 0x3c,
+	MMC_READ_BUFFER_CAPACITY = 0x5c,
+	MMC_READ_CAPACITY = 0x25,
+	MMC_READ_CD = 0xbe,
+	MMC_READ_CD_MSF = 0xb9,
+	MMC_READ_DISC_INFORMATION = 0x51,
+	MMC_READ_DVD_STRUCTURE = 0xad,
+	MMC_READ_FORMAT_CAPACITIES = 0x23,
+	MMC_READ_SUB_CHANNEL = 0x42,
+	MMC_READ_TOC_PMA_ATIP = 0x43,
+	MMC_READ_TRACK_INFORMATION = 0x52,
+	MMC_REPAIR_TRACK = 0x58,
+	MMC_REPORT_KEY = 0xa4,
+	MMC_REQUEST_SENSE = 0x03,
+	MMC_RESERVE_TRACK = 0x53,
+	MMC_SCAN = 0xba,
+	MMC_SEEK_10 = 0x2b,
+	MMC_SEND_CUE_SHEET = 0x5d,
+	MMC_SEND_DVD_STRUCTURE = 0xbf,
+	MMC_SEND_KEY = 0xa3,
+	MMC_SEND_OPC_INFORMATION = 0x54,
+	MMC_SET_CD_SPEED = 0xbb,
+	MMC_SET_READ_AHEAD = 0xa7,
+	MMC_SET_STREAMING = 0xb6,
+	MMC_START_STOP_UNIT = 0x1b,
+	MMC_STOP_PLAY_SCAN = 0x4e,
+	MMC_SYNCHRONIZE_CACHE = 0x35,
+	MMC_TEST_UNIT_READY = 0x00,
+	MMC_VERIFY_10 = 0x2f,
+	MMC_WRITE_10 = 0xa2,
+	MMC_WRITE_12 = 0xaa,
+	MMC_WRITE_AND_VERIFY_10 = 0x2e,
+	MMC_WRITE_BUFFER = 0x3b,
+};
+
+enum ssc_opcode {
+	SSC_ERASE_6 = 0x19,
+	SSC_FORMAT_MEDIUM = 0x04,
+	SSC_LOAD_UNLOAD = 0x1b,
+	SSC_LOCATE_10 = 0x2b,
+	SSC_LOCATE_16 = 0x92,
+	SSC_MOVE_MEDIUM_ATTACHED = 0xa7,
+	SSC_READ_6 = 0x08,
+	SSC_READ_BLOCK_LIMITS = 0x05,
+	SSC_READ_ELEMENT_STATUS_ATTACHED = 0xb4,
+	SSC_READ_POSITION = 0x34,
+	SSC_READ_REVERSE_6 = 0x0f,
+	SSC_RECOVER_BUFFERED_DATA = 0x14,
+	SSC_REPORT_DENSITY_SUPPORT = 0x44,
+	SSC_REWIND = 0x01,
+	SSC_SET_CAPACITY = 0x0b,
+	SSC_SPACE_6 = 0x11,
+	SSC_SPACE_16 = 0x91,
+	SSC_VERIFY_6 = 0x13,
+	SSC_WRITE_6 = 0x0a,
+	SSC_WRITE_FILEMARKS_6 = 0x10,
+};
+
+enum spc_vpd {
+	SPC_VPD_DEVICE_IDENTIFICATION = 0x83,
+	SPC_VPD_EXTENDED_INQUIRY_DATA = 0x86,
+	SPC_VPD_MANAGEMENT_NETWORK_ADDRESSES = 0x85,
+	SPC_VPD_MODE_PAGE_POLICY = 0x87,
+	SPC_VPD_SCSI_PORTS = 0x88,
+	SPC_VPD_SOFTWARE_INTERFACE_IDENTIFICATION = 0x84,
+	SPC_VPD_SUPPORTED_VPD_PAGES = 0x00,
+	SPC_VPD_UNIT_SERIAL_NUMBER = 0x80,
+	SPC_VPD_BLOCK_LIMITS = 0xb0,
+	SPC_VPD_BLOCK_DEV_CHARS = 0xb1,
+	SPC_VPD_BLOCK_THIN_PROVISION = 0xb2,
+};
+
+enum {
+	SPC_PERIPHERAL_DEVICE_TYPE_DISK = 0x00,
+	SPC_PERIPHERAL_DEVICE_TYPE_TAPE = 0x01,
+	SPC_PERIPHERAL_DEVICE_TYPE_DVD = 0x05,
+	SPC_PERIPHERAL_DEVICE_TYPE_CHANGER = 0x08,
+
+	SPC_VERSION_NONE = 0x00,
+	SPC_VERSION_SPC = 0x03,
+	SPC_VERSION_SPC2 = 0x04,
+	SPC_VERSION_SPC3 = 0x05,
+	SPC_VERSION_SPC4 = 0x06,
+
+	SPC_PROTOCOL_IDENTIFIER_FC = 0x00,
+	SPC_PROTOCOL_IDENTIFIER_PSCSI = 0x01,
+	SPC_PROTOCOL_IDENTIFIER_SSA = 0x02,
+	SPC_PROTOCOL_IDENTIFIER_IEEE1394 = 0x03,
+	SPC_PROTOCOL_IDENTIFIER_RDMA = 0x04,
+	SPC_PROTOCOL_IDENTIFIER_ISCSI = 0x05,
+	SPC_PROTOCOL_IDENTIFIER_SAS = 0x06,
+	SPC_PROTOCOL_IDENTIFIER_ADT = 0x07,
+	SPC_PROTOCOL_IDENTIFIER_ATA = 0x08,
+
+	SPC_VPD_CODE_SET_BINARY = 0x01,
+	SPC_VPD_CODE_SET_ASCII = 0x02,
+	SPC_VPD_CODE_SET_UTF8 = 0x03,
+
+	SPC_VPD_ASSOCIATION_LOGICAL_UNIT = 0x00,
+	SPC_VPD_ASSOCIATION_TARGET_PORT = 0x01,
+	SPC_VPD_ASSOCIATION_TARGET_DEVICE = 0x02,
+
+	SPC_VPD_IDENTIFIER_TYPE_VENDOR_SPECIFIC = 0x00,
+	SPC_VPD_IDENTIFIER_TYPE_T10_VENDOR_ID = 0x01,
+	SPC_VPD_IDENTIFIER_TYPE_EUI64 = 0x02,
+	SPC_VPD_IDENTIFIER_TYPE_NAA = 0x03,
+	SPC_VPD_IDENTIFIER_TYPE_RELATIVE_TARGET_PORT = 0x04,
+	SPC_VPD_IDENTIFIER_TYPE_TARGET_PORT_GROUP = 0x05,
+	SPC_VPD_IDENTIFIER_TYPE_LOGICAL_UNIT_GROUP = 0x06,
+	SPC_VPD_IDENTIFIER_TYPE_MD5_LOGICAL_UNIT = 0x07,
+	SPC_VPD_IDENTIFIER_TYPE_SCSI_NAME = 0x08,
+};
+
+struct scsi_cdb_inquiry {
+	uint8_t opcode;
+	uint8_t evpd;
+	uint8_t page_code;
+	uint8_t alloc_len[2];
+	uint8_t control;
+};
+
+struct scsi_cdb_inquiry_data {
+	uint8_t peripheral;
+	uint8_t rmb;
+	uint8_t version;
+	uint8_t response;
+	uint8_t add_len;
+	uint8_t flags;
+	uint8_t flags2;
+	uint8_t flags3;
+	uint8_t t10_vendor_id[8];
+	uint8_t product_id[16];
+	uint8_t product_rev[4];
+	uint8_t vendor[20];
+	uint8_t ius;
+	uint8_t reserved;
+	uint8_t desc[];
+};
+
+struct scsi_vpd_page {
+	uint8_t peripheral;
+	uint8_t page_code;
+	uint8_t alloc_len[2];
+	uint8_t params[];
+};
+
+#define SCSI_VEXT_REF_CHK		0x01
+#define SCSI_VEXT_APP_CHK		0x02
+#define SCSI_VEXT_GRD_CHK		0x04
+#define SCSI_VEXT_SIMPSUP		0x01
+#define SCSI_VEXT_ORDSUP		0x02
+#define SCSI_VEXT_HEADSUP		0x04
+#define SCSI_VEXT_PRIOR_SUP	0x08
+#define SCSI_VEXT_GROUP_SUP	0x10
+#define SCSI_VEXT_UASK_SUP		0x20
+#define SCSI_VEXT_V_SUP		0x01
+#define SCSI_VEXT_NV_SUP		0x02
+#define SCSI_VEXT_CRD_SUP		0x04
+#define SCSI_VEXT_WU_SUP		0x08
+
+struct scsi_vpd_ext_inquiry {
+	uint8_t peripheral;
+	uint8_t page_code;
+	uint8_t alloc_len[2];
+	uint8_t check;
+	uint8_t sup;
+	uint8_t sup2;
+	uint8_t luiclr;
+	uint8_t cbcs;
+	uint8_t micro_dl;
+	uint8_t reserved[54];
+};
+
+#define SPC_VPD_DESIG_PIV	0x80
+
+/* designation descriptor */
+struct scsi_desig_desc {
+	uint8_t code_set	: 4;
+	uint8_t protocol_id	: 4;
+	uint8_t type		: 4;
+	uint8_t association	: 2;
+	uint8_t reserved0	: 1;
+	uint8_t piv		: 1;
+	uint8_t reserved1;
+	uint8_t	len;
+	uint8_t desig[];
+};
+
+/* mode page policy descriptor */
+struct scsi_mpage_policy_desc {
+	uint8_t page_code;
+	uint8_t sub_page_code;
+	uint8_t policy;
+	uint8_t reserved;
+};
+
+/* target port descriptor */
+struct scsi_tgt_port_desc {
+	uint8_t code_set;
+	uint8_t desig_type;
+	uint8_t reserved;
+	uint8_t	len;
+	uint8_t designator[];
+};
+
+/* SCSI port designation descriptor */
+struct scsi_port_desc {
+	uint16_t reserved;
+	uint16_t rel_port_id;
+	uint16_t reserved2;
+	uint16_t init_port_len;
+	uint16_t init_port_id;
+	uint16_t reserved3;
+	uint16_t tgt_desc_len;
+	uint8_t tgt_desc[];
+};
+
+/* SCSI UNMAP block descriptor */
+struct scsi_unmap_bdesc {
+	/* UNMAP LOGICAL BLOCK ADDRESS */
+	uint64_t lba;
+
+	/* NUMBER OF LOGICAL BLOCKS */
+	uint32_t block_count;
+
+	/* RESERVED */
+	uint32_t reserved;
+};
+
+#define SCSI_UNMAP_LBPU				(1 << 7)
+#define SCSI_UNMAP_LBPWS			(1 << 6)
+#define SCSI_UNMAP_LBPWS10			(1 << 5)
+
+#define SCSI_UNMAP_FULL_PROVISIONING	0x00
+#define SCSI_UNMAP_RESOURCE_PROVISIONING	0x01
+#define SCSI_UNMAP_THIN_PROVISIONING	0x02
+
+#endif /* _SCSI_SPEC_H */
diff --git a/examples/vhost_scsi/vhost_scsi.c b/examples/vhost_scsi/vhost_scsi.c
new file mode 100644
index 0000000..160c2e0
--- /dev/null
+++ b/examples/vhost_scsi/vhost_scsi.c
@@ -0,0 +1,472 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2010-2017 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdint.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <semaphore.h>
+#include <linux/virtio_scsi.h>
+#include <linux/virtio_ring.h>
+
+#include <rte_atomic.h>
+#include <rte_cycles.h>
+#include <rte_log.h>
+#include <rte_malloc.h>
+#include <rte_vhost.h>
+
+#include "vhost_scsi.h"
+#include "scsi_spec.h"
+
+#define VIRTIO_SCSI_FEATURES ((1 << VIRTIO_F_NOTIFY_ON_EMPTY) |\
+			      (1 << VIRTIO_RING_F_EVENT_IDX) |\
+			      (1 << VIRTIO_SCSI_F_INOUT) |\
+			      (1 << VIRTIO_SCSI_F_CHANGE))
+
+/* Path to folder where character device will be created. Can be set by user. */
+static char dev_pathname[PATH_MAX] = "";
+
+static struct vhost_scsi_ctrlr *g_vhost_ctrlr;
+static int g_should_stop;
+static sem_t exit_sem;
+
+#define NUM_OF_SCSI_QUEUES 3
+
+static struct vhost_scsi_ctrlr *
+vhost_scsi_ctrlr_find(__rte_unused const char *ctrlr_name)
+{
+	/* currently we only support 1 socket file fd */
+	return g_vhost_ctrlr;
+}
+
+static uint64_t gpa_to_vva(int vid, uint64_t gpa)
+{
+	char path[PATH_MAX];
+	struct vhost_scsi_ctrlr *ctrlr;
+	int ret = 0;
+
+	ret = rte_vhost_get_ifname(vid, path, PATH_MAX);
+	if (ret) {
+		fprintf(stderr, "Cannot get socket name\n");
+		assert(ret != 0);
+	}
+
+	ctrlr = vhost_scsi_ctrlr_find(path);
+	if (!ctrlr) {
+		fprintf(stderr, "Controller is not ready\n");
+		assert(ctrlr != NULL);
+	}
+
+	assert(ctrlr->mem != NULL);
+
+	return rte_vhost_gpa_to_vva(ctrlr->mem, gpa);
+}
+
+static struct vring_desc *
+descriptor_get_next(struct vring_desc *vq_desc, struct vring_desc *cur_desc)
+{
+	return &vq_desc[cur_desc->next];
+}
+
+static bool
+descriptor_has_next(struct vring_desc *cur_desc)
+{
+	return !!(cur_desc->flags & VRING_DESC_F_NEXT);
+}
+
+static bool
+descriptor_is_wr(struct vring_desc *cur_desc)
+{
+	return !!(cur_desc->flags & VRING_DESC_F_WRITE);
+}
+
+static void
+submit_completion(struct vhost_scsi_task *task)
+{
+	struct rte_vhost_vring *vq;
+	struct vring_used *used;
+
+	vq = task->vq;
+	used = vq->used;
+	/* Fill out the next entry in the "used" ring.  id = the
+	 * index of the descriptor that contained the SCSI request.
+	 * len = the total amount of data transferred for the SCSI
+	 * request. We must report the correct len, for variable
+	 * length SCSI CDBs, where we may return less data than
+	 * allocated by the guest VM.
+	 */
+	used->ring[used->idx & (vq->size - 1)].id = task->req_idx;
+	used->ring[used->idx & (vq->size - 1)].len = task->data_len;
+	used->idx++;
+
+	/* Send an interrupt back to the guest VM so that it knows
+	 * a completion is ready to be processed.
+	 */
+	eventfd_write(vq->callfd, (eventfd_t)1);
+}
+
+static void
+vhost_process_read_payload_chain(struct vhost_scsi_task *task)
+{
+	void *data;
+
+	task->iovs_cnt = 0;
+	task->resp = (void *)gpa_to_vva(task->bdev->vid, task->desc->addr);
+
+	while (descriptor_has_next(task->desc)) {
+		task->desc = descriptor_get_next(task->vq->desc, task->desc);
+		data = (void *)gpa_to_vva(task->bdev->vid, task->desc->addr);
+		task->iovs[task->iovs_cnt].iov_base = data;
+		task->iovs[task->iovs_cnt].iov_len = task->desc->len;
+		task->data_len += task->desc->len;
+		task->iovs_cnt++;
+	}
+}
+
+static void
+vhost_process_write_payload_chain(struct vhost_scsi_task *task)
+{
+	void *data;
+
+	task->iovs_cnt = 0;
+
+	do {
+		data = (void *)gpa_to_vva(task->bdev->vid, task->desc->addr);
+		task->iovs[task->iovs_cnt].iov_base = data;
+		task->iovs[task->iovs_cnt].iov_len = task->desc->len;
+		task->data_len += task->desc->len;
+		task->iovs_cnt++;
+		task->desc = descriptor_get_next(task->vq->desc, task->desc);
+	} while (descriptor_has_next(task->desc));
+
+	task->resp = (void *)gpa_to_vva(task->bdev->vid, task->desc->addr);
+}
+
+static struct vhost_block_dev *
+vhost_scsi_bdev_construct(const char *bdev_name, const char *bdev_serial,
+			  uint32_t blk_size, uint64_t blk_cnt,
+			  bool wce_enable)
+{
+	struct vhost_block_dev *bdev;
+
+	bdev = rte_zmalloc(NULL, sizeof(*bdev), RTE_CACHE_LINE_SIZE);
+	if (!bdev)
+		return NULL;
+
+	strncpy(bdev->name, bdev_name, sizeof(bdev->name));
+	strncpy(bdev->product_name, bdev_serial, sizeof(bdev->product_name));
+	bdev->blocklen = blk_size;
+	bdev->blockcnt = blk_cnt;
+	bdev->write_cache = wce_enable;
+
+	/* use memory as disk storage space */
+	bdev->data = rte_zmalloc(NULL, blk_cnt * blk_size, 0);
+	if (!bdev->data) {
+		fprintf(stderr, "no enough reseverd huge memory for disk\n");
+		return NULL;
+	}
+
+	return bdev;
+}
+
+static void
+process_requestq(struct vhost_scsi_ctrlr *ctrlr, uint32_t q_idx)
+{
+	int ret;
+	struct vhost_scsi_queue *scsi_vq;
+	struct rte_vhost_vring *vq;
+
+	scsi_vq = &ctrlr->bdev->queues[q_idx];
+	vq = &scsi_vq->vq;
+	ret = rte_vhost_get_vhost_vring(ctrlr->bdev->vid, q_idx, vq);
+	assert(ret == 0);
+
+	while (vq->avail->idx != scsi_vq->last_used_idx) {
+		int req_idx;
+		uint16_t last_idx;
+		struct vhost_scsi_task *task;
+
+		last_idx = scsi_vq->last_used_idx & (vq->size - 1);
+		req_idx = vq->avail->ring[last_idx];
+
+		task = rte_zmalloc(NULL, sizeof(*task), 0);
+		assert(task != NULL);
+
+		task->ctrlr = ctrlr;
+		task->bdev = ctrlr->bdev;
+		task->vq = vq;
+		task->req_idx = req_idx;
+		task->desc = &task->vq->desc[task->req_idx];
+
+		/* does not support indirect descriptors */
+		assert((task->desc->flags & VRING_DESC_F_INDIRECT) == 0);
+		scsi_vq->last_used_idx++;
+
+		task->req = (void *)gpa_to_vva(task->bdev->vid,
+					       task->desc->addr);
+
+		task->desc = descriptor_get_next(task->vq->desc, task->desc);
+		if (!descriptor_has_next(task->desc)) {
+			task->dxfer_dir = SCSI_DIR_NONE;
+			task->resp = (void *)gpa_to_vva(task->bdev->vid,
+							task->desc->addr);
+
+		} else if (!descriptor_is_wr(task->desc)) {
+			task->dxfer_dir = SCSI_DIR_TO_DEV;
+			vhost_process_write_payload_chain(task);
+		} else {
+			task->dxfer_dir = SCSI_DIR_FROM_DEV;
+			vhost_process_read_payload_chain(task);
+		}
+
+		ret = vhost_bdev_process_scsi_commands(ctrlr->bdev, task);
+		if (ret) {
+			/* invalid response */
+			task->resp->response = VIRTIO_SCSI_S_BAD_TARGET;
+		} else {
+			/* successfully */
+			task->resp->response = VIRTIO_SCSI_S_OK;
+			task->resp->status = 0;
+		}
+		submit_completion(task);
+		rte_free(task);
+	}
+}
+
+/* Main framework for processing IOs */
+static void *
+ctrlr_worker(void *arg)
+{
+	uint32_t idx, num;
+	struct vhost_scsi_ctrlr *ctrlr = (struct vhost_scsi_ctrlr *)arg;
+	cpu_set_t cpuset;
+	pthread_t thread;
+
+	thread = pthread_self();
+	CPU_ZERO(&cpuset);
+	CPU_SET(0, &cpuset);
+	pthread_setaffinity_np(thread, sizeof(cpu_set_t), &cpuset);
+
+	num =  rte_vhost_get_vring_num(ctrlr->bdev->vid);
+	fprintf(stdout, "Ctrlr Worker Thread Started with %u Vring\n", num);
+
+	if (num != NUM_OF_SCSI_QUEUES) {
+		fprintf(stderr, "Only 1 IO queue are supported\n");
+		exit(0);
+	}
+
+	while (!g_should_stop && ctrlr->bdev != NULL) {
+		/* At least 3 vrings, currently only can support 1 IO queue
+		 * Queue 2 for IO queue, does not support TMF and hotplug
+		 * for the example application now
+		 */
+		for (idx = 2; idx < num; idx++)
+			process_requestq(ctrlr, idx);
+	}
+
+	fprintf(stdout, "Ctrlr Worker Thread Exiting\n");
+	sem_post(&exit_sem);
+	return NULL;
+}
+
+static int
+new_device(int vid)
+{
+	char path[PATH_MAX];
+	struct vhost_scsi_ctrlr *ctrlr;
+	struct vhost_scsi_queue *scsi_vq;
+	struct rte_vhost_vring *vq;
+	pthread_t tid;
+	int i, ret;
+
+	ret = rte_vhost_get_ifname(vid, path, PATH_MAX);
+	if (ret) {
+		fprintf(stderr, "Cannot get socket name\n");
+		return -1;
+	}
+
+	ctrlr = vhost_scsi_ctrlr_find(path);
+	if (!ctrlr) {
+		fprintf(stderr, "Controller is not ready\n");
+		return -1;
+	}
+
+	ret = rte_vhost_get_mem_table(vid, &ctrlr->mem);
+	if (ret) {
+		fprintf(stderr, "Get Controller memory region failed\n");
+		return -1;
+	}
+	assert(ctrlr->mem != NULL);
+
+	/* hardcoded block device information with 128MiB */
+	ctrlr->bdev = vhost_scsi_bdev_construct("malloc0", "vhost_scsi_malloc0",
+						4096, 32768, 0);
+	if (!ctrlr->bdev)
+		return -1;
+
+	ctrlr->bdev->vid = vid;
+
+	/* Disable Notifications */
+	for (i = 0; i < NUM_OF_SCSI_QUEUES; i++) {
+		rte_vhost_enable_guest_notification(vid, i, 0);
+		/* restore used index */
+		scsi_vq = &ctrlr->bdev->queues[i];
+		vq = &scsi_vq->vq;
+		ret = rte_vhost_get_vhost_vring(ctrlr->bdev->vid, i, vq);
+		assert(ret == 0);
+		scsi_vq->last_used_idx = vq->used->idx;
+		scsi_vq->last_avail_idx = vq->used->idx;
+	}
+
+	g_should_stop = 0;
+	fprintf(stdout, "New Device %s, Device ID %d\n", path, vid);
+	if (pthread_create(&tid, NULL, &ctrlr_worker, ctrlr) < 0) {
+		fprintf(stderr, "Worker Thread Started Failed\n");
+		return -1;
+	}
+	pthread_detach(tid);
+	return 0;
+}
+
+static void
+destroy_device(int vid)
+{
+	char path[PATH_MAX];
+	struct vhost_scsi_ctrlr *ctrlr;
+
+	rte_vhost_get_ifname(vid, path, PATH_MAX);
+	fprintf(stdout, "Destroy %s Device ID %d\n", path, vid);
+	ctrlr = vhost_scsi_ctrlr_find(path);
+	if (!ctrlr) {
+		fprintf(stderr, "Destroy Ctrlr Failed\n");
+		return;
+	}
+	ctrlr->bdev = NULL;
+	g_should_stop = 1;
+
+	sem_wait(&exit_sem);
+}
+
+static const struct vhost_device_ops vhost_scsi_device_ops = {
+	.new_device =  new_device,
+	.destroy_device = destroy_device,
+};
+
+static struct vhost_scsi_ctrlr *
+vhost_scsi_ctrlr_construct(const char *ctrlr_name)
+{
+	int ret;
+	struct vhost_scsi_ctrlr *ctrlr;
+	char *path;
+	char cwd[PATH_MAX];
+
+	/* always use current directory */
+	path = getcwd(cwd, PATH_MAX);
+	if (!path) {
+		fprintf(stderr, "Cannot get current working directory\n");
+		return NULL;
+	}
+	snprintf(dev_pathname, sizeof(dev_pathname), "%s/%s", path, ctrlr_name);
+
+	if (access(dev_pathname, F_OK) != -1) {
+		if (unlink(dev_pathname) != 0)
+			rte_exit(EXIT_FAILURE, "Cannot remove %s.\n",
+				 dev_pathname);
+	}
+
+	fprintf(stdout, "socket file: %s\n", dev_pathname);
+
+	if (rte_vhost_driver_register(dev_pathname, 0) != 0) {
+		fprintf(stderr, "socket %s already exists\n", dev_pathname);
+		return NULL;
+	}
+
+	ret = rte_vhost_driver_set_features(dev_pathname, VIRTIO_SCSI_FEATURES);
+	if (ret) {
+		fprintf(stderr, "Set vhost driver features failed\n");
+		return NULL;
+	}
+
+	ctrlr = rte_zmalloc(NULL, sizeof(*ctrlr), RTE_CACHE_LINE_SIZE);
+	if (!ctrlr)
+		return NULL;
+
+	ctrlr->name = strdup(ctrlr_name);
+
+	rte_vhost_driver_callback_register(dev_pathname,
+					   &vhost_scsi_device_ops);
+
+	return ctrlr;
+}
+
+static void
+signal_handler(__rte_unused int signum)
+{
+
+	if (access(dev_pathname, F_OK) == 0)
+		unlink(dev_pathname);
+	exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	signal(SIGINT, signal_handler);
+
+	/* init EAL */
+	ret = rte_eal_init(argc, argv);
+	if (ret < 0)
+		rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");
+
+	g_vhost_ctrlr = vhost_scsi_ctrlr_construct("vhost.socket");
+	if (g_vhost_ctrlr == NULL) {
+		fprintf(stderr, "Construct vhost scsi controller failed\n");
+		return 0;
+	}
+
+	if (sem_init(&exit_sem, 0, 0) < 0) {
+		fprintf(stderr, "Error init exit_sem\n");
+		return -1;
+	}
+
+	rte_vhost_driver_start(dev_pathname);
+
+	/* loop for exit the application */
+	while (1)
+		sleep(1);
+
+	return 0;
+}
+
diff --git a/examples/vhost_scsi/vhost_scsi.h b/examples/vhost_scsi/vhost_scsi.h
new file mode 100644
index 0000000..b5340cc
--- /dev/null
+++ b/examples/vhost_scsi/vhost_scsi.h
@@ -0,0 +1,250 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2010-2017 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _VHOST_SCSI_H_
+#define _VHOST_SCSI_H_
+
+#include <sys/uio.h>
+#include <stdint.h>
+#include <linux/virtio_scsi.h>
+#include <linux/virtio_ring.h>
+
+#include <rte_vhost.h>
+
+static inline uint16_t
+from_be16(const void *ptr)
+{
+	const uint8_t *tmp = (const uint8_t *)ptr;
+
+	return (((uint16_t)tmp[0] << 8) | tmp[1]);
+}
+
+static inline void
+to_be16(void *out, uint16_t in)
+{
+	uint8_t *tmp = (uint8_t *)out;
+
+	tmp[0] = (in >> 8) & 0xFF;
+	tmp[1] = in & 0xFF;
+}
+
+static inline uint32_t
+from_be32(const void *ptr)
+{
+	const uint8_t *tmp = (const uint8_t *)ptr;
+
+	return (((uint32_t)tmp[0] << 24) |
+		((uint32_t)tmp[1] << 16) |
+		((uint32_t)tmp[2] << 8) |
+		((uint32_t)tmp[3]));
+}
+
+static inline void
+to_be32(void *out, uint32_t in)
+{
+	uint8_t *tmp = (uint8_t *)out;
+
+	tmp[0] = (in >> 24) & 0xFF;
+	tmp[1] = (in >> 16) & 0xFF;
+	tmp[2] = (in >> 8) & 0xFF;
+	tmp[3] = in & 0xFF;
+}
+
+static inline uint64_t
+from_be64(const void *ptr)
+{
+	const uint8_t *tmp = (const uint8_t *)ptr;
+
+	return (((uint64_t)tmp[0] << 56) |
+		((uint64_t)tmp[1] << 48) |
+		((uint64_t)tmp[2] << 40) |
+		((uint64_t)tmp[3] << 32) |
+		((uint64_t)tmp[4] << 24) |
+		((uint64_t)tmp[5] << 16) |
+		((uint64_t)tmp[6] << 8) |
+		((uint64_t)tmp[7]));
+}
+
+static inline void
+to_be64(void *out, uint64_t in)
+{
+	uint8_t *tmp = (uint8_t *)out;
+
+	tmp[0] = (in >> 56) & 0xFF;
+	tmp[1] = (in >> 48) & 0xFF;
+	tmp[2] = (in >> 40) & 0xFF;
+	tmp[3] = (in >> 32) & 0xFF;
+	tmp[4] = (in >> 24) & 0xFF;
+	tmp[5] = (in >> 16) & 0xFF;
+	tmp[6] = (in >> 8) & 0xFF;
+	tmp[7] = in & 0xFF;
+}
+
+static inline uint16_t
+from_le16(const void *ptr)
+{
+	const uint8_t *tmp = (const uint8_t *)ptr;
+
+	return (((uint16_t)tmp[1] << 8) | tmp[0]);
+}
+
+static inline void
+to_le16(void *out, uint16_t in)
+{
+	uint8_t *tmp = (uint8_t *)out;
+
+	tmp[1] = (in >> 8) & 0xFF;
+	tmp[0] = in & 0xFF;
+}
+
+static inline uint32_t
+from_le32(const void *ptr)
+{
+	const uint8_t *tmp = (const uint8_t *)ptr;
+
+	return (((uint32_t)tmp[3] << 24) |
+		((uint32_t)tmp[2] << 16) |
+		((uint32_t)tmp[1] << 8) |
+		((uint32_t)tmp[0]));
+}
+
+static inline void
+to_le32(void *out, uint32_t in)
+{
+	uint8_t *tmp = (uint8_t *)out;
+
+	tmp[3] = (in >> 24) & 0xFF;
+	tmp[2] = (in >> 16) & 0xFF;
+	tmp[1] = (in >> 8) & 0xFF;
+	tmp[0] = in & 0xFF;
+}
+
+static inline uint64_t
+from_le64(const void *ptr)
+{
+	const uint8_t *tmp = (const uint8_t *)ptr;
+
+	return (((uint64_t)tmp[7] << 56) |
+		((uint64_t)tmp[6] << 48) |
+		((uint64_t)tmp[5] << 40) |
+		((uint64_t)tmp[4] << 32) |
+		((uint64_t)tmp[3] << 24) |
+		((uint64_t)tmp[2] << 16) |
+		((uint64_t)tmp[1] << 8) |
+		((uint64_t)tmp[0]));
+}
+
+static inline void
+to_le64(void *out, uint64_t in)
+{
+	uint8_t *tmp = (uint8_t *)out;
+
+	tmp[7] = (in >> 56) & 0xFF;
+	tmp[6] = (in >> 48) & 0xFF;
+	tmp[5] = (in >> 40) & 0xFF;
+	tmp[4] = (in >> 32) & 0xFF;
+	tmp[3] = (in >> 24) & 0xFF;
+	tmp[2] = (in >> 16) & 0xFF;
+	tmp[1] = (in >> 8) & 0xFF;
+	tmp[0] = in & 0xFF;
+}
+
+struct vaddr_region {
+	void *vaddr;
+	uint64_t len;
+};
+
+struct vhost_scsi_queue {
+	struct rte_vhost_vring vq;
+	uint16_t last_avail_idx;
+	uint16_t last_used_idx;
+};
+
+struct vhost_block_dev {
+	/** ID for vhost library. */
+	int vid;
+	/** Queues for the block device */
+	struct vhost_scsi_queue queues[8];
+	/** Unique name for this block device. */
+	char name[64];
+
+	/** Unique product name for this kind of block device. */
+	char product_name[256];
+
+	/** Size in bytes of a logical block for the backend */
+	uint32_t blocklen;
+
+	/** Number of blocks */
+	uint64_t blockcnt;
+
+	/** write cache enabled, not used at the moment */
+	int write_cache;
+
+	/** use memory as disk storage space */
+	uint8_t *data;
+};
+
+struct vhost_scsi_ctrlr {
+	char *name;
+	/** Only support 1 LUN for the example */
+	struct vhost_block_dev *bdev;
+	/** VM memory region */
+	struct rte_vhost_memory *mem;
+} __rte_cache_aligned;
+
+#define VHOST_SCSI_MAX_IOVS 128
+
+enum scsi_data_dir {
+	SCSI_DIR_NONE = 0,
+	SCSI_DIR_TO_DEV = 1,
+	SCSI_DIR_FROM_DEV = 2,
+};
+
+struct vhost_scsi_task {
+	int req_idx;
+	uint32_t dxfer_dir;
+	uint32_t data_len;
+	struct virtio_scsi_cmd_req *req;
+	struct virtio_scsi_cmd_resp *resp;
+	struct iovec iovs[VHOST_SCSI_MAX_IOVS];
+	uint32_t iovs_cnt;
+	struct vring_desc *desc;
+	struct rte_vhost_vring *vq;
+	struct vhost_block_dev *bdev;
+	struct vhost_scsi_ctrlr *ctrlr;
+};
+
+int vhost_bdev_process_scsi_commands(struct vhost_block_dev *bdev,
+				     struct vhost_scsi_task *task);
+
+#endif /* _VHOST_SCSI_H_ */