hw/scsi/vhost-scsi.c - qemu - Git at Google

 /*
  * vhost_scsi host device
  *
  * Copyright IBM, Corp. 2011
  *
  * Authors:
  *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
  *
  * Changes for QEMU mainline + tcm_vhost kernel upstream:
  *  Nicholas Bellinger <nab@risingtidesystems.com>
  *
  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  * See the COPYING.LIB file in the top-level directory.
  *
  */

 #include "qemu/osdep.h"
 #include <linux/vhost.h>
 #include <sys/ioctl.h>
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 #include "monitor/monitor.h"
 #include "migration/blocker.h"
 #include "hw/virtio/vhost-scsi.h"
 #include "hw/virtio/vhost.h"
 #include "hw/virtio/virtio-scsi.h"
 #include "hw/virtio/virtio-bus.h"
 #include "hw/fw-path-provider.h"
 #include "hw/qdev-properties.h"
 #include "qemu/cutils.h"
 #include "sysemu/sysemu.h"

 /* Features supported by host kernel. */
 static const int kernel_feature_bits[] = {
     VIRTIO_F_NOTIFY_ON_EMPTY,
     VIRTIO_RING_F_INDIRECT_DESC,
     VIRTIO_RING_F_EVENT_IDX,
     VIRTIO_SCSI_F_HOTPLUG,
     VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };

 static int vhost_scsi_set_endpoint(VHostSCSI *s)
 {
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
     const VhostOps *vhost_ops = vsc->dev.vhost_ops;
     struct vhost_scsi_target backend;
     int ret;

     memset(&backend, 0, sizeof(backend));
     pstrcpy(backend.vhost_wwpn, sizeof(backend.vhost_wwpn), vs->conf.wwpn);
     ret = vhost_ops->vhost_scsi_set_endpoint(&vsc->dev, &backend);
     if (ret < 0) {
         return -errno;
     }
     return 0;
 }

 static void vhost_scsi_clear_endpoint(VHostSCSI *s)
 {
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
     struct vhost_scsi_target backend;
     const VhostOps *vhost_ops = vsc->dev.vhost_ops;

     memset(&backend, 0, sizeof(backend));
     pstrcpy(backend.vhost_wwpn, sizeof(backend.vhost_wwpn), vs->conf.wwpn);
     vhost_ops->vhost_scsi_clear_endpoint(&vsc->dev, &backend);
 }

 static int vhost_scsi_start(VHostSCSI *s)
 {
     int ret, abi_version;
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
     const VhostOps *vhost_ops = vsc->dev.vhost_ops;
     Error *local_err = NULL;

     ret = vhost_ops->vhost_scsi_get_abi_version(&vsc->dev, &abi_version);
     if (ret < 0) {
         return -errno;
     }
     if (abi_version > VHOST_SCSI_ABI_VERSION) {
         error_report("vhost-scsi: The running tcm_vhost kernel abi_version:"
                      " %d is greater than vhost_scsi userspace supports: %d,"
                      " please upgrade your version of QEMU", abi_version,
                      VHOST_SCSI_ABI_VERSION);
         return -ENOSYS;
     }

     ret = vhost_scsi_common_start(vsc, &local_err);
     if (ret < 0) {
         error_reportf_err(local_err, "Error starting vhost-scsi: ");
         return ret;
     }

     ret = vhost_scsi_set_endpoint(s);
     if (ret < 0) {
         error_report("Error setting vhost-scsi endpoint");
         vhost_scsi_common_stop(vsc);
     }

     return ret;
 }

 static void vhost_scsi_stop(VHostSCSI *s)
 {
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);

     vhost_scsi_clear_endpoint(s);
     vhost_scsi_common_stop(vsc);
 }

 static void vhost_scsi_set_status(VirtIODevice *vdev, uint8_t val)
 {
     VHostSCSI *s = VHOST_SCSI(vdev);
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
     bool start = (val & VIRTIO_CONFIG_S_DRIVER_OK);

     if (!vdev->vm_running) {
         start = false;
     }

     if (vhost_dev_is_started(&vsc->dev) == start) {
         return;
     }

     if (start) {
         int ret;

         ret = vhost_scsi_start(s);
         if (ret < 0) {
             error_report("unable to start vhost-scsi: %s", strerror(-ret));
             exit(1);
         }
     } else {
         vhost_scsi_stop(s);
     }
 }

 static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
 }

 static int vhost_scsi_pre_save(void *opaque)
 {
     VHostSCSICommon *vsc = opaque;

     /* At this point, backend must be stopped, otherwise
      * it might keep writing to memory. */
     assert(!vhost_dev_is_started(&vsc->dev));

     return 0;
 }

 static const VMStateDescription vmstate_virtio_vhost_scsi = {
     .name = "virtio-vhost_scsi",
     .minimum_version_id = 1,
     .version_id = 1,
     .fields = (const VMStateField[]) {
         VMSTATE_VIRTIO_DEVICE,
         VMSTATE_END_OF_LIST()
     },
     .pre_save = vhost_scsi_pre_save,
 };

 static int vhost_scsi_set_workers(VHostSCSICommon *vsc, bool per_virtqueue)
 {
     struct vhost_dev *dev = &vsc->dev;
     struct vhost_vring_worker vq_worker;
     struct vhost_worker_state worker;
     int i, ret;

     /* Use default worker */
     if (!per_virtqueue || dev->nvqs == VHOST_SCSI_VQ_NUM_FIXED + 1) {
         return 0;
     }

     /*
      * ctl/evt share the first worker since it will be rare for them
      * to send cmds while IO is running.
      */
     for (i = VHOST_SCSI_VQ_NUM_FIXED + 1; i < dev->nvqs; i++) {
         memset(&worker, 0, sizeof(worker));

         ret = dev->vhost_ops->vhost_new_worker(dev, &worker);
         if (ret == -ENOTTY) {
             /*
              * worker ioctls are not implemented so just ignore and
              * and continue device setup.
              */
             warn_report("vhost-scsi: Backend supports a single worker. "
                         "Ignoring worker_per_virtqueue=true setting.");
             ret = 0;
             break;
         } else if (ret) {
             break;
         }

         memset(&vq_worker, 0, sizeof(vq_worker));
         vq_worker.worker_id = worker.worker_id;
         vq_worker.index = i;

         ret = dev->vhost_ops->vhost_attach_vring_worker(dev, &vq_worker);
         if (ret == -ENOTTY) {
             /*
              * It's a bug for the kernel to have supported the worker creation
              * ioctl but not attach.
              */
             dev->vhost_ops->vhost_free_worker(dev, &worker);
             break;
         } else if (ret) {
             break;
         }
     }

     return ret;
 }

 static void vhost_scsi_realize(DeviceState *dev, Error **errp)
 {
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(dev);
     Error *err = NULL;
     int vhostfd = -1;
     int ret;
     struct vhost_virtqueue *vqs = NULL;

     if (!vs->conf.wwpn) {
         error_setg(errp, "vhost-scsi: missing wwpn");
         return;
     }

     if (vs->conf.vhostfd) {
         vhostfd = monitor_fd_param(monitor_cur(), vs->conf.vhostfd, errp);
         if (vhostfd == -1) {
             error_prepend(errp, "vhost-scsi: unable to parse vhostfd: ");
             return;
         }
     } else {
         vhostfd = open("/dev/vhost-scsi", O_RDWR);
         if (vhostfd < 0) {
             error_setg(errp, "vhost-scsi: open vhost char device failed: %s",
                        strerror(errno));
             return;
         }
     }

     virtio_scsi_common_realize(dev,
                                vhost_dummy_handle_output,
                                vhost_dummy_handle_output,
                                vhost_dummy_handle_output,
                                &err);
     if (err != NULL) {
         error_propagate(errp, err);
         goto close_fd;
     }

     if (!vsc->migratable) {
         error_setg(&vsc->migration_blocker,
                 "vhost-scsi does not support migration in all cases. "
                 "When external environment supports it (Orchestrator migrates "
                 "target SCSI device state or use shared storage over network), "
                 "set 'migratable' property to true to enable migration.");
         if (migrate_add_blocker_normal(&vsc->migration_blocker, errp) < 0) {
             goto free_virtio;
         }
     }

     vsc->dev.nvqs = VHOST_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
     vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
     vsc->dev.vqs = vqs;
     vsc->dev.vq_index = 0;
     vsc->dev.backend_features = 0;

     ret = vhost_dev_init(&vsc->dev, (void *)(uintptr_t)vhostfd,
                          VHOST_BACKEND_TYPE_KERNEL, 0, errp);
     if (ret < 0) {
         /*
          * vhost_dev_init calls vhost_dev_cleanup on error, which closes
          * vhostfd, don't double close it.
          */
         vhostfd = -1;
         goto free_vqs;
     }

     ret = vhost_scsi_set_workers(vsc, vs->conf.worker_per_virtqueue);
     if (ret < 0) {
         error_setg(errp, "vhost-scsi: vhost worker setup failed: %s",
                    strerror(-ret));
         goto free_vqs;
     }

     /* At present, channel and lun both are 0 for bootable vhost-scsi disk */
     vsc->channel = 0;
     vsc->lun = 0;
     /* Note: we can also get the minimum tpgt from kernel */
     vsc->target = vs->conf.boot_tpgt;

     return;

  free_vqs:
     g_free(vqs);
     if (!vsc->migratable) {
         migrate_del_blocker(&vsc->migration_blocker);
     }
  free_virtio:
     virtio_scsi_common_unrealize(dev);
  close_fd:
     if (vhostfd >= 0) {
         close(vhostfd);
     }
     return;
 }

 static void vhost_scsi_unrealize(DeviceState *dev)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(dev);
     struct vhost_virtqueue *vqs = vsc->dev.vqs;

     if (!vsc->migratable) {
         migrate_del_blocker(&vsc->migration_blocker);
     }

     /* This will stop vhost backend. */
     vhost_scsi_set_status(vdev, 0);

     vhost_dev_cleanup(&vsc->dev);
     g_free(vqs);

     virtio_scsi_common_unrealize(dev);
 }

 static struct vhost_dev *vhost_scsi_get_vhost(VirtIODevice *vdev)
 {
     VHostSCSI *s = VHOST_SCSI(vdev);
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
     return &vsc->dev;
 }

 static Property vhost_scsi_properties[] = {
     DEFINE_PROP_STRING("vhostfd", VirtIOSCSICommon, conf.vhostfd),
     DEFINE_PROP_STRING("wwpn", VirtIOSCSICommon, conf.wwpn),
     DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0),
     DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues,
                        VIRTIO_SCSI_AUTO_NUM_QUEUES),
     DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size,
                        128),
     DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSICommon, conf.seg_max_adjust,
                       true),
     DEFINE_PROP_UINT32("max_sectors", VirtIOSCSICommon, conf.max_sectors,
                        0xFFFF),
     DEFINE_PROP_UINT32("cmd_per_lun", VirtIOSCSICommon, conf.cmd_per_lun, 128),
     DEFINE_PROP_BIT64("t10_pi", VHostSCSICommon, host_features,
                                                  VIRTIO_SCSI_F_T10_PI,
                                                  false),
     DEFINE_PROP_BOOL("migratable", VHostSCSICommon, migratable, false),
     DEFINE_PROP_BOOL("worker_per_virtqueue", VirtIOSCSICommon,
                      conf.worker_per_virtqueue, false),
     DEFINE_PROP_END_OF_LIST(),
 };

 static void vhost_scsi_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
     FWPathProviderClass *fwc = FW_PATH_PROVIDER_CLASS(klass);

     device_class_set_props(dc, vhost_scsi_properties);
     dc->vmsd = &vmstate_virtio_vhost_scsi;
     set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
     vdc->realize = vhost_scsi_realize;
     vdc->unrealize = vhost_scsi_unrealize;
     vdc->get_features = vhost_scsi_common_get_features;
     vdc->set_config = vhost_scsi_common_set_config;
     vdc->set_status = vhost_scsi_set_status;
     vdc->get_vhost = vhost_scsi_get_vhost;
     fwc->get_dev_path = vhost_scsi_common_get_fw_dev_path;
 }

 static void vhost_scsi_instance_init(Object *obj)
 {
     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(obj);

     vsc->feature_bits = kernel_feature_bits;

     device_add_bootindex_property(obj, &vsc->bootindex, "bootindex", NULL,
                                   DEVICE(vsc));
 }

 static const TypeInfo vhost_scsi_info = {
     .name = TYPE_VHOST_SCSI,
     .parent = TYPE_VHOST_SCSI_COMMON,
     .instance_size = sizeof(VHostSCSI),
     .class_init = vhost_scsi_class_init,
     .instance_init = vhost_scsi_instance_init,
     .interfaces = (InterfaceInfo[]) {
         { TYPE_FW_PATH_PROVIDER },
         { }
     },
 };

 static void virtio_register_types(void)
 {
     type_register_static(&vhost_scsi_info);
 }

 type_init(virtio_register_types)
	/*
	* vhost_scsi host device
	*
	* Copyright IBM, Corp. 2011
	*
	* Authors:
	* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
	*
	* Changes for QEMU mainline + tcm_vhost kernel upstream:
	* Nicholas Bellinger <nab@risingtidesystems.com>
	*
	* This work is licensed under the terms of the GNU LGPL, version 2 or later.
	* See the COPYING.LIB file in the top-level directory.
	*
	*/

	#include "qemu/osdep.h"
	#include <linux/vhost.h>
	#include <sys/ioctl.h>
	#include "qapi/error.h"
	#include "qemu/error-report.h"
	#include "qemu/module.h"
	#include "monitor/monitor.h"
	#include "migration/blocker.h"
	#include "hw/virtio/vhost-scsi.h"
	#include "hw/virtio/vhost.h"
	#include "hw/virtio/virtio-scsi.h"
	#include "hw/virtio/virtio-bus.h"
	#include "hw/fw-path-provider.h"
	#include "hw/qdev-properties.h"
	#include "qemu/cutils.h"
	#include "sysemu/sysemu.h"

	/* Features supported by host kernel. */
	static const int kernel_feature_bits[] = {
	VIRTIO_F_NOTIFY_ON_EMPTY,
	VIRTIO_RING_F_INDIRECT_DESC,
	VIRTIO_RING_F_EVENT_IDX,
	VIRTIO_SCSI_F_HOTPLUG,
	VIRTIO_F_RING_RESET,
	VHOST_INVALID_FEATURE_BIT
	};

	static int vhost_scsi_set_endpoint(VHostSCSI *s)
	{
	VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
	const VhostOps *vhost_ops = vsc->dev.vhost_ops;
	struct vhost_scsi_target backend;
	int ret;

	memset(&backend, 0, sizeof(backend));
	pstrcpy(backend.vhost_wwpn, sizeof(backend.vhost_wwpn), vs->conf.wwpn);
	ret = vhost_ops->vhost_scsi_set_endpoint(&vsc->dev, &backend);
	if (ret < 0) {
	return -errno;
	}
	return 0;
	}

	static void vhost_scsi_clear_endpoint(VHostSCSI *s)
	{
	VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
	struct vhost_scsi_target backend;
	const VhostOps *vhost_ops = vsc->dev.vhost_ops;

	memset(&backend, 0, sizeof(backend));
	pstrcpy(backend.vhost_wwpn, sizeof(backend.vhost_wwpn), vs->conf.wwpn);
	vhost_ops->vhost_scsi_clear_endpoint(&vsc->dev, &backend);
	}

	static int vhost_scsi_start(VHostSCSI *s)
	{
	int ret, abi_version;
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
	const VhostOps *vhost_ops = vsc->dev.vhost_ops;
	Error *local_err = NULL;

	ret = vhost_ops->vhost_scsi_get_abi_version(&vsc->dev, &abi_version);
	if (ret < 0) {
	return -errno;
	}
	if (abi_version > VHOST_SCSI_ABI_VERSION) {
	error_report("vhost-scsi: The running tcm_vhost kernel abi_version:"
	" %d is greater than vhost_scsi userspace supports: %d,"
	" please upgrade your version of QEMU", abi_version,
	VHOST_SCSI_ABI_VERSION);
	return -ENOSYS;
	}

	ret = vhost_scsi_common_start(vsc, &local_err);
	if (ret < 0) {
	error_reportf_err(local_err, "Error starting vhost-scsi: ");
	return ret;
	}

	ret = vhost_scsi_set_endpoint(s);
	if (ret < 0) {
	error_report("Error setting vhost-scsi endpoint");
	vhost_scsi_common_stop(vsc);
	}

	return ret;
	}

	static void vhost_scsi_stop(VHostSCSI *s)
	{
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);

	vhost_scsi_clear_endpoint(s);
	vhost_scsi_common_stop(vsc);
	}

	static void vhost_scsi_set_status(VirtIODevice *vdev, uint8_t val)
	{
	VHostSCSI *s = VHOST_SCSI(vdev);
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
	bool start = (val & VIRTIO_CONFIG_S_DRIVER_OK);

	if (!vdev->vm_running) {
	start = false;
	}

	if (vhost_dev_is_started(&vsc->dev) == start) {
	return;
	}

	if (start) {
	int ret;

	ret = vhost_scsi_start(s);
	if (ret < 0) {
	error_report("unable to start vhost-scsi: %s", strerror(-ret));
	exit(1);
	}
	} else {
	vhost_scsi_stop(s);
	}
	}

	static void vhost_dummy_handle_output(VirtIODevice vdev, VirtQueue vq)
	{
	}

	static int vhost_scsi_pre_save(void *opaque)
	{
	VHostSCSICommon *vsc = opaque;

	/* At this point, backend must be stopped, otherwise
	* it might keep writing to memory. */
	assert(!vhost_dev_is_started(&vsc->dev));

	return 0;
	}

	static const VMStateDescription vmstate_virtio_vhost_scsi = {
	.name = "virtio-vhost_scsi",
	.minimum_version_id = 1,
	.version_id = 1,
	.fields = (const VMStateField[]) {
	VMSTATE_VIRTIO_DEVICE,
	VMSTATE_END_OF_LIST()
	},
	.pre_save = vhost_scsi_pre_save,
	};

	static int vhost_scsi_set_workers(VHostSCSICommon *vsc, bool per_virtqueue)
	{
	struct vhost_dev *dev = &vsc->dev;
	struct vhost_vring_worker vq_worker;
	struct vhost_worker_state worker;
	int i, ret;

	/* Use default worker */
	if (!per_virtqueue \|\| dev->nvqs == VHOST_SCSI_VQ_NUM_FIXED + 1) {
	return 0;
	}

	/*
	* ctl/evt share the first worker since it will be rare for them
	* to send cmds while IO is running.
	*/
	for (i = VHOST_SCSI_VQ_NUM_FIXED + 1; i < dev->nvqs; i++) {
	memset(&worker, 0, sizeof(worker));

	ret = dev->vhost_ops->vhost_new_worker(dev, &worker);
	if (ret == -ENOTTY) {
	/*
	* worker ioctls are not implemented so just ignore and
	* and continue device setup.
	*/
	warn_report("vhost-scsi: Backend supports a single worker. "
	"Ignoring worker_per_virtqueue=true setting.");
	ret = 0;
	break;
	} else if (ret) {
	break;
	}

	memset(&vq_worker, 0, sizeof(vq_worker));
	vq_worker.worker_id = worker.worker_id;
	vq_worker.index = i;

	ret = dev->vhost_ops->vhost_attach_vring_worker(dev, &vq_worker);
	if (ret == -ENOTTY) {
	/*
	* It's a bug for the kernel to have supported the worker creation
	* ioctl but not attach.
	*/
	dev->vhost_ops->vhost_free_worker(dev, &worker);
	break;
	} else if (ret) {
	break;
	}
	}

	return ret;
	}

	static void vhost_scsi_realize(DeviceState dev, Error *errp)
	{
	VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(dev);
	Error *err = NULL;
	int vhostfd = -1;
	int ret;
	struct vhost_virtqueue *vqs = NULL;

	if (!vs->conf.wwpn) {
	error_setg(errp, "vhost-scsi: missing wwpn");
	return;
	}

	if (vs->conf.vhostfd) {
	vhostfd = monitor_fd_param(monitor_cur(), vs->conf.vhostfd, errp);
	if (vhostfd == -1) {
	error_prepend(errp, "vhost-scsi: unable to parse vhostfd: ");
	return;
	}
	} else {
	vhostfd = open("/dev/vhost-scsi", O_RDWR);
	if (vhostfd < 0) {
	error_setg(errp, "vhost-scsi: open vhost char device failed: %s",
	strerror(errno));
	return;
	}
	}

	virtio_scsi_common_realize(dev,
	vhost_dummy_handle_output,
	vhost_dummy_handle_output,
	vhost_dummy_handle_output,
	&err);
	if (err != NULL) {
	error_propagate(errp, err);
	goto close_fd;
	}

	if (!vsc->migratable) {
	error_setg(&vsc->migration_blocker,
	"vhost-scsi does not support migration in all cases. "
	"When external environment supports it (Orchestrator migrates "
	"target SCSI device state or use shared storage over network), "
	"set 'migratable' property to true to enable migration.");
	if (migrate_add_blocker_normal(&vsc->migration_blocker, errp) < 0) {
	goto free_virtio;
	}
	}

	vsc->dev.nvqs = VHOST_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
	vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
	vsc->dev.vqs = vqs;
	vsc->dev.vq_index = 0;
	vsc->dev.backend_features = 0;

	ret = vhost_dev_init(&vsc->dev, (void *)(uintptr_t)vhostfd,
	VHOST_BACKEND_TYPE_KERNEL, 0, errp);
	if (ret < 0) {
	/*
	* vhost_dev_init calls vhost_dev_cleanup on error, which closes
	* vhostfd, don't double close it.
	*/
	vhostfd = -1;
	goto free_vqs;
	}

	ret = vhost_scsi_set_workers(vsc, vs->conf.worker_per_virtqueue);
	if (ret < 0) {
	error_setg(errp, "vhost-scsi: vhost worker setup failed: %s",
	strerror(-ret));
	goto free_vqs;
	}

	/* At present, channel and lun both are 0 for bootable vhost-scsi disk */
	vsc->channel = 0;
	vsc->lun = 0;
	/* Note: we can also get the minimum tpgt from kernel */
	vsc->target = vs->conf.boot_tpgt;

	return;

	free_vqs:
	g_free(vqs);
	if (!vsc->migratable) {
	migrate_del_blocker(&vsc->migration_blocker);
	}
	free_virtio:
	virtio_scsi_common_unrealize(dev);
	close_fd:
	if (vhostfd >= 0) {
	close(vhostfd);
	}
	return;
	}

	static void vhost_scsi_unrealize(DeviceState *dev)
	{
	VirtIODevice *vdev = VIRTIO_DEVICE(dev);
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(dev);
	struct vhost_virtqueue *vqs = vsc->dev.vqs;

	if (!vsc->migratable) {
	migrate_del_blocker(&vsc->migration_blocker);
	}

	/* This will stop vhost backend. */
	vhost_scsi_set_status(vdev, 0);

	vhost_dev_cleanup(&vsc->dev);
	g_free(vqs);

	virtio_scsi_common_unrealize(dev);
	}

	static struct vhost_dev vhost_scsi_get_vhost(VirtIODevice vdev)
	{
	VHostSCSI *s = VHOST_SCSI(vdev);
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
	return &vsc->dev;
	}

	static Property vhost_scsi_properties[] = {
	DEFINE_PROP_STRING("vhostfd", VirtIOSCSICommon, conf.vhostfd),
	DEFINE_PROP_STRING("wwpn", VirtIOSCSICommon, conf.wwpn),
	DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0),
	DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues,
	VIRTIO_SCSI_AUTO_NUM_QUEUES),
	DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size,
	128),
	DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSICommon, conf.seg_max_adjust,
	true),
	DEFINE_PROP_UINT32("max_sectors", VirtIOSCSICommon, conf.max_sectors,
	0xFFFF),
	DEFINE_PROP_UINT32("cmd_per_lun", VirtIOSCSICommon, conf.cmd_per_lun, 128),
	DEFINE_PROP_BIT64("t10_pi", VHostSCSICommon, host_features,
	VIRTIO_SCSI_F_T10_PI,
	false),
	DEFINE_PROP_BOOL("migratable", VHostSCSICommon, migratable, false),
	DEFINE_PROP_BOOL("worker_per_virtqueue", VirtIOSCSICommon,
	conf.worker_per_virtqueue, false),
	DEFINE_PROP_END_OF_LIST(),
	};

	static void vhost_scsi_class_init(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);
	VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
	FWPathProviderClass *fwc = FW_PATH_PROVIDER_CLASS(klass);

	device_class_set_props(dc, vhost_scsi_properties);
	dc->vmsd = &vmstate_virtio_vhost_scsi;
	set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
	vdc->realize = vhost_scsi_realize;
	vdc->unrealize = vhost_scsi_unrealize;
	vdc->get_features = vhost_scsi_common_get_features;
	vdc->set_config = vhost_scsi_common_set_config;
	vdc->set_status = vhost_scsi_set_status;
	vdc->get_vhost = vhost_scsi_get_vhost;
	fwc->get_dev_path = vhost_scsi_common_get_fw_dev_path;
	}

	static void vhost_scsi_instance_init(Object *obj)
	{
	VHostSCSICommon *vsc = VHOST_SCSI_COMMON(obj);

	vsc->feature_bits = kernel_feature_bits;

	device_add_bootindex_property(obj, &vsc->bootindex, "bootindex", NULL,
	DEVICE(vsc));
	}

	static const TypeInfo vhost_scsi_info = {
	.name = TYPE_VHOST_SCSI,
	.parent = TYPE_VHOST_SCSI_COMMON,
	.instance_size = sizeof(VHostSCSI),
	.class_init = vhost_scsi_class_init,
	.instance_init = vhost_scsi_instance_init,
	.interfaces = (InterfaceInfo[]) {
	{ TYPE_FW_PATH_PROVIDER },
	{ }
	},
	};

	static void virtio_register_types(void)
	{
	type_register_static(&vhost_scsi_info);
	}

	type_init(virtio_register_types)