[1/2] vus: Introduce vhost-user-scsi host device

This commit introduces a vhost-user device for SCSI. This is based
on the existing vhost-scsi implementation, but done over vhost-user
instead. It also uses a chardev to connect to the backend. Unlike
vhost-scsi (today), VMs using vhost-user-scsi can be live migrated.

To use it, one must configure Qemu with --enable-vhost-user-scsi and
start Qemu with a command line equivalent to:

qemu-system-x86_64 \
       -chardev socket,id=vus0,path=/tmp/vus.sock \
       -device vhost-user-scsi-pci,chardev=vus0,bus=pci.0,addr=0x4

A separate commit presents a sample application linked with libiscsi to
provide a backend for vhost-user-scsi.

Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
---
 configure                           |  10 ++
 hw/scsi/Makefile.objs               |   1 +
 hw/scsi/vhost-user-scsi.c           | 299 ++++++++++++++++++++++++++++++++++++
 hw/virtio/virtio-pci.c              |  58 +++++++
 hw/virtio/virtio-pci.h              |  15 ++
 include/hw/virtio/vhost-user-scsi.h |  45 ++++++
 include/hw/virtio/virtio-scsi.h     |   5 +
 7 files changed, 433 insertions(+)
 create mode 100644 hw/scsi/vhost-user-scsi.c
 create mode 100644 include/hw/virtio/vhost-user-scsi.h

On 26/10/2016 17:26, Felipe Franciosi wrote:
> This commit introduces a vhost-user device for SCSI. This is based
> on the existing vhost-scsi implementation, but done over vhost-user
> instead. It also uses a chardev to connect to the backend. Unlike
> vhost-scsi (today), VMs using vhost-user-scsi can be live migrated.
> 
> To use it, one must configure Qemu with --enable-vhost-user-scsi and
> start Qemu with a command line equivalent to:
> 
> qemu-system-x86_64 \
>        -chardev socket,id=vus0,path=/tmp/vus.sock \
>        -device vhost-user-scsi-pci,chardev=vus0,bus=pci.0,addr=0x4
> 
> A separate commit presents a sample application linked with libiscsi to
> provide a backend for vhost-user-scsi.

Hi,

most of the code you copy can be kept in one place only, by using the
vhost_ops struct.  Please make a hierarchy

    virtio-scsi-common
        vhost-scsi-common
            vhost-scsi (adds vhostfd+wwpn)
            vhost-user-scsi (adds chardev)

with abstract methods in vhost-scsi-common to abstract e.g. opening
/dev/scsi and setting/clearing the endpoint, which are only needed by
vhost-scsi's realize method.  This should avoid the duplication.

Thanks!

Paolo

> Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
> ---
>  configure                           |  10 ++
>  hw/scsi/Makefile.objs               |   1 +
>  hw/scsi/vhost-user-scsi.c           | 299 ++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-pci.c              |  58 +++++++
>  hw/virtio/virtio-pci.h              |  15 ++
>  include/hw/virtio/vhost-user-scsi.h |  45 ++++++
>  include/hw/virtio/virtio-scsi.h     |   5 +
>  7 files changed, 433 insertions(+)
>  create mode 100644 hw/scsi/vhost-user-scsi.c
>  create mode 100644 include/hw/virtio/vhost-user-scsi.h
> 
> diff --git a/configure b/configure
> index d3dafcb..0574ff2 100755
> --- a/configure
> +++ b/configure
> @@ -228,6 +228,7 @@ xfs=""
>  
>  vhost_net="no"
>  vhost_scsi="no"
> +vhost_user_scsi="no"
>  vhost_vsock="no"
>  kvm="no"
>  rdma=""
> @@ -677,6 +678,7 @@ Haiku)
>    kvm="yes"
>    vhost_net="yes"
>    vhost_scsi="yes"
> +  vhost_user_scsi="yes"
>    vhost_vsock="yes"
>    QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$(pwd)/linux-headers $QEMU_INCLUDES"
>  ;;
> @@ -1019,6 +1021,10 @@ for opt do
>    ;;
>    --enable-vhost-scsi) vhost_scsi="yes"
>    ;;
> +  --disable-vhost-user-scsi) vhost_user_scsi="no"
> +  ;;
> +  --enable-vhost-user-scsi) vhost_user_scsi="yes"
> +  ;;
>    --disable-vhost-vsock) vhost_vsock="no"
>    ;;
>    --enable-vhost-vsock) vhost_vsock="yes"
> @@ -4951,6 +4957,7 @@ echo "posix_madvise     $posix_madvise"
>  echo "libcap-ng support $cap_ng"
>  echo "vhost-net support $vhost_net"
>  echo "vhost-scsi support $vhost_scsi"
> +echo "vhost-user-scsi support $vhost_user_scsi"
>  echo "vhost-vsock support $vhost_vsock"
>  echo "Trace backends    $trace_backends"
>  if have_backend "simple"; then
> @@ -5336,6 +5343,9 @@ fi
>  if test "$vhost_scsi" = "yes" ; then
>    echo "CONFIG_VHOST_SCSI=y" >> $config_host_mak
>  fi
> +if test "$vhost_user_scsi" = "yes" ; then
> +  echo "CONFIG_VHOST_USER_SCSI=y" >> $config_host_mak
> +fi
>  if test "$vhost_net" = "yes" ; then
>    echo "CONFIG_VHOST_NET_USED=y" >> $config_host_mak
>  fi
> diff --git a/hw/scsi/Makefile.objs b/hw/scsi/Makefile.objs
> index 5a2248b..3338aad 100644
> --- a/hw/scsi/Makefile.objs
> +++ b/hw/scsi/Makefile.objs
> @@ -11,4 +11,5 @@ obj-$(CONFIG_PSERIES) += spapr_vscsi.o
>  ifeq ($(CONFIG_VIRTIO),y)
>  obj-y += virtio-scsi.o virtio-scsi-dataplane.o
>  obj-$(CONFIG_VHOST_SCSI) += vhost-scsi.o
> +obj-$(CONFIG_VHOST_USER_SCSI) += vhost-user-scsi.o
>  endif
> diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
> new file mode 100644
> index 0000000..a7b9839
> --- /dev/null
> +++ b/hw/scsi/vhost-user-scsi.c
> @@ -0,0 +1,299 @@
> +/*
> + * vhost-user-scsi host device
> + *
> + * Copyright (c) 2016 Nutanix Inc. All rights reserved.
> + *
> + * Author:
> + *  Felipe Franciosi <felipe@nutanix.com>
> + *
> + * This work is largely based on the "vhost-scsi" implementation by:
> + *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
> + *  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 "migration/vmstate.h"
> +#include "qapi/error.h"
> +#include "qemu/error-report.h"
> +#include "qemu/typedefs.h"
> +#include "qom/object.h"
> +#include "hw/fw-path-provider.h"
> +#include "hw/qdev-core.h"
> +#include "hw/virtio/vhost.h"
> +#include "hw/virtio/vhost-backend.h"
> +#include "hw/virtio/vhost-user-scsi.h"
> +#include "hw/virtio/virtio.h"
> +#include "hw/virtio/virtio-access.h"
> +#include "hw/virtio/virtio-bus.h"
> +#include "sysemu/char.h"
> +
> +/* Features supported by the host application */
> +static const int user_feature_bits[] = {
> +    VIRTIO_F_NOTIFY_ON_EMPTY,
> +    VIRTIO_RING_F_INDIRECT_DESC,
> +    VIRTIO_RING_F_EVENT_IDX,
> +    VIRTIO_SCSI_F_HOTPLUG,
> +    VHOST_INVALID_FEATURE_BIT
> +};
> +
> +static int vhost_user_scsi_start(VHostUserSCSI *s)
> +{
> +    int ret, i;
> +    VirtIODevice *vdev = VIRTIO_DEVICE(s);
> +    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +
> +    if (!k->set_guest_notifiers) {
> +        error_report("binding does not support guest notifiers");
> +        return -ENOSYS;
> +    }
> +
> +    ret = vhost_dev_enable_notifiers(&s->dev, vdev);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    s->dev.acked_features = vdev->guest_features;
> +    ret = vhost_dev_start(&s->dev, vdev);
> +    if (ret < 0) {
> +        error_report("Error starting vhost-user device");
> +        goto err_notifiers;
> +    }
> +
> +    ret = k->set_guest_notifiers(qbus->parent, s->dev.nvqs, true);
> +    if (ret < 0) {
> +        error_report("Error binding guest notifier");
> +        goto err_vhost_stop;
> +    }
> +
> +    /* guest_notifier_mask/pending not used yet, so just unmask
> +     * everything here.  virtio-pci will do the right thing by
> +     * enabling/disabling irqfd.
> +     */
> +    for (i = 0; i < s->dev.nvqs; i++) {
> +        vhost_virtqueue_mask(&s->dev, vdev, s->dev.vq_index + i, false);
> +    }
> +
> +    return ret;
> +
> +err_vhost_stop:
> +    vhost_dev_stop(&s->dev, vdev);
> +err_notifiers:
> +    vhost_dev_disable_notifiers(&s->dev, vdev);
> +    return ret;
> +}
> +
> +static void vhost_user_scsi_stop(VHostUserSCSI *s)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(s);
> +    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +    int ret = 0;
> +
> +    vhost_dev_stop(&s->dev, vdev);
> +    vhost_dev_disable_notifiers(&s->dev, vdev);
> +
> +    if (k->set_guest_notifiers) {
> +        ret = k->set_guest_notifiers(qbus->parent, s->dev.nvqs, false);
> +        if (ret < 0) {
> +            error_report("vhost guest notifier cleanup failed: %d", ret);
> +        }
> +    }
> +    assert(ret >= 0);
> +}
> +
> +static uint64_t vhost_user_scsi_get_features(VirtIODevice *vdev,
> +                                             uint64_t features,
> +                                             Error **errp)
> +{
> +    VHostUserSCSI *s = VHOST_USER_SCSI(vdev);
> +
> +    return vhost_get_features(&s->dev, user_feature_bits, features);
> +}
> +
> +static void vhost_user_scsi_set_config(VirtIODevice *vdev,
> +                                       const uint8_t *config)
> +{
> +    VirtIOSCSIConfig *scsiconf = (VirtIOSCSIConfig *)config;
> +    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
> +
> +    if ((uint32_t)virtio_ldl_p(vdev, &scsiconf->sense_size) != vs->sense_size ||
> +        (uint32_t)virtio_ldl_p(vdev, &scsiconf->cdb_size) != vs->cdb_size) {
> +        error_report("vhost-user-scsi doesn't allow sense or CDB sizes change");
> +        exit(1);
> +    }
> +}
> +
> +static void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t status)
> +{
> +    VHostUserSCSI *s = (VHostUserSCSI *)vdev;
> +    bool start = (status & VIRTIO_CONFIG_S_DRIVER_OK) && vdev->vm_running;
> +
> +    if (s->dev.started == start) {
> +        return;
> +    }
> +
> +    if (start) {
> +        int ret;
> +
> +        ret = vhost_user_scsi_start(s);
> +        if (ret < 0) {
> +            error_report("unable to start vhost-user-scsi: %s", strerror(-ret));
> +            exit(1);
> +        }
> +    } else {
> +        vhost_user_scsi_stop(s);
> +    }
> +}
> +
> +static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
> +{
> +}
> +
> +static void vhost_user_scsi_save(QEMUFile *f, void *opaque)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
> +    virtio_save(vdev, f);
> +}
> +
> +static int vhost_user_scsi_load(QEMUFile *f, void *opaque, int version_id)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
> +    return virtio_load(vdev, f, version_id);
> +}
> +
> +static void vhost_user_scsi_realize(DeviceState *dev, Error **errp)
> +{
> +    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
> +    VHostUserSCSI *s = VHOST_USER_SCSI(dev);
> +    static int vhost_user_scsi_id;
> +    Error *err = NULL;
> +    int ret;
> +
> +    if (!vs->conf.chardev.chr) {
> +        error_setg(errp, "vhost-user-scsi: missing chardev");
> +        return;
> +    }
> +
> +    virtio_scsi_common_realize(dev, &err, vhost_dummy_handle_output,
> +                               vhost_dummy_handle_output,
> +                               vhost_dummy_handle_output);
> +    if (err != NULL) {
> +        error_propagate(errp, err);
> +        return;
> +    }
> +
> +    s->dev.nvqs = VHOST_USER_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
> +    s->dev.vqs = g_new(struct vhost_virtqueue, s->dev.nvqs);
> +    s->dev.vq_index = 0;
> +    s->dev.backend_features = 0;
> +
> +    ret = vhost_dev_init(&s->dev, (void *)&vs->conf.chardev,
> +                         VHOST_BACKEND_TYPE_USER, 0);
> +    if (ret < 0) {
> +        error_setg(errp, "vhost-user-scsi: vhost initialization failed: %s",
> +                   strerror(-ret));
> +        return;
> +    }
> +
> +    /* Channel and lun both are 0 for bootable vhost-user-scsi disk */
> +    s->channel = 0;
> +    s->lun = 0;
> +    s->target = vs->conf.boot_tpgt;
> +
> +    register_savevm(dev, "vhost-user-scsi", vhost_user_scsi_id++, 1,
> +                    vhost_user_scsi_save, vhost_user_scsi_load, s);
> +}
> +
> +static void vhost_user_scsi_unrealize(DeviceState *dev, Error **errp)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> +    VHostUserSCSI *s = VHOST_USER_SCSI(dev);
> +
> +    /* This will stop the vhost backend. */
> +    vhost_user_scsi_set_status(vdev, 0);
> +
> +    vhost_dev_cleanup(&s->dev);
> +    g_free(s->dev.vqs);
> +
> +    virtio_scsi_common_unrealize(dev, errp);
> +}
> +
> +/*
> + * Implementation of an interface to adjust firmware path
> + * for the bootindex property handling.
> + */
> +static char *vhost_user_scsi_get_fw_dev_path(FWPathProvider *p, BusState *bus,
> +                                             DeviceState *dev)
> +{
> +    VHostUserSCSI *s = VHOST_USER_SCSI(dev);
> +    /* format: /channel@<channel>/vhost-user-scsi@<target>,<lun> */
> +    return g_strdup_printf("/channel@%x/%s@%x,%x", s->channel,
> +                           qdev_fw_name(dev), s->target, s->lun);
> +}
> +
> +static Property vhost_user_scsi_properties[] = {
> +    DEFINE_PROP_CHR("chardev", VHostUserSCSI,
> +                    parent_obj.conf.chardev),
> +    DEFINE_PROP_UINT32("boot_tpgt", VHostUserSCSI,
> +                       parent_obj.conf.boot_tpgt, 0),
> +    DEFINE_PROP_UINT32("num_queues", VHostUserSCSI,
> +                       parent_obj.conf.num_queues, 1),
> +    DEFINE_PROP_UINT32("max_sectors", VHostUserSCSI,
> +                       parent_obj.conf.max_sectors, 0xFFFF),
> +    DEFINE_PROP_UINT32("cmd_per_lun", VHostUserSCSI,
> +                       parent_obj.conf.cmd_per_lun, 128),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void vhost_user_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);
> +
> +    dc->props = vhost_user_scsi_properties;
> +    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
> +    vdc->realize = vhost_user_scsi_realize;
> +    vdc->unrealize = vhost_user_scsi_unrealize;
> +    vdc->get_features = vhost_user_scsi_get_features;
> +    vdc->set_config = vhost_user_scsi_set_config;
> +    vdc->set_status = vhost_user_scsi_set_status;
> +    fwc->get_dev_path = vhost_user_scsi_get_fw_dev_path;
> +}
> +
> +static void vhost_user_scsi_instance_init(Object *obj)
> +{
> +    VHostUserSCSI *dev = VHOST_USER_SCSI(obj);
> +    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(obj);
> +
> +    // Add the bootindex property for this object
> +    device_add_bootindex_property(obj, &dev->bootindex, "bootindex", NULL,
> +                                  DEVICE(dev), NULL);
> +
> +    // Set boot index according the the device config
> +    object_property_set_int(obj, vs->conf.bootindex, "bootindex", NULL);
> +}
> +
> +static const TypeInfo vhost_user_scsi_info = {
> +    .name = TYPE_VHOST_USER_SCSI,
> +    .parent = TYPE_VIRTIO_SCSI_COMMON,
> +    .instance_size = sizeof(VHostUserSCSI),
> +    .class_init = vhost_user_scsi_class_init,
> +    .instance_init = vhost_user_scsi_instance_init,
> +    .interfaces = (InterfaceInfo[]) {
> +        { TYPE_FW_PATH_PROVIDER },
> +        { }
> +    },
> +};
> +
> +static void virtio_register_types(void)
> +{
> +    type_register_static(&vhost_user_scsi_info);
> +}
> +
> +type_init(virtio_register_types)
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 06831de..b996d37 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -2098,6 +2098,61 @@ static const TypeInfo vhost_scsi_pci_info = {
>  };
>  #endif
>  
> +/* vhost-user-scsi-pci */
> +#ifdef CONFIG_VHOST_USER_SCSI
> +static Property vhost_user_scsi_pci_properties[] = {
> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
> +                       DEV_NVECTORS_UNSPECIFIED),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void vhost_user_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
> +{
> +    VHostUserSCSIPCI *dev = VHOST_USER_SCSI_PCI(vpci_dev);
> +    DeviceState *vdev = DEVICE(&dev->vdev);
> +    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
> +
> +    if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
> +        vpci_dev->nvectors = vs->conf.num_queues + 3;
> +    }
> +
> +    qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
> +    object_property_set_bool(OBJECT(vdev), true, "realized", errp);
> +}
> +
> +static void vhost_user_scsi_pci_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
> +    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
> +    k->realize = vhost_user_scsi_pci_realize;
> +    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
> +    dc->props = vhost_user_scsi_pci_properties;
> +    pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
> +    pcidev_k->device_id = PCI_DEVICE_ID_VIRTIO_SCSI;
> +    pcidev_k->revision = 0x00;
> +    pcidev_k->class_id = PCI_CLASS_STORAGE_SCSI;
> +}
> +
> +static void vhost_user_scsi_pci_instance_init(Object *obj)
> +{
> +    VHostUserSCSIPCI *dev = VHOST_USER_SCSI_PCI(obj);
> +
> +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
> +                                TYPE_VHOST_USER_SCSI);
> +    object_property_add_alias(obj, "bootindex", OBJECT(&dev->vdev),
> +                              "bootindex", &error_abort);
> +}
> +
> +static const TypeInfo vhost_user_scsi_pci_info = {
> +    .name          = TYPE_VHOST_USER_SCSI_PCI,
> +    .parent        = TYPE_VIRTIO_PCI,
> +    .instance_size = sizeof(VHostUserSCSIPCI),
> +    .instance_init = vhost_user_scsi_pci_instance_init,
> +    .class_init    = vhost_user_scsi_pci_class_init,
> +};
> +#endif /* CONFIG_VHOST_USER_SCSI */
> +
>  /* vhost-vsock-pci */
>  
>  #ifdef CONFIG_VHOST_VSOCK
> @@ -2577,6 +2632,9 @@ static void virtio_pci_register_types(void)
>  #ifdef CONFIG_VHOST_SCSI
>      type_register_static(&vhost_scsi_pci_info);
>  #endif
> +#ifdef CONFIG_VHOST_USER_SCSI
> +    type_register_static(&vhost_user_scsi_pci_info);
> +#endif
>  #ifdef CONFIG_VHOST_VSOCK
>      type_register_static(&vhost_vsock_pci_info);
>  #endif
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index b4edea6..404b2c4 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -31,6 +31,9 @@
>  #ifdef CONFIG_VHOST_SCSI
>  #include "hw/virtio/vhost-scsi.h"
>  #endif
> +#ifdef CONFIG_VHOST_USER_SCSI
> +#include "hw/virtio/vhost-user-scsi.h"
> +#endif
>  #ifdef CONFIG_VHOST_VSOCK
>  #include "hw/virtio/vhost-vsock.h"
>  #endif
> @@ -42,6 +45,7 @@ typedef struct VirtIOBalloonPCI VirtIOBalloonPCI;
>  typedef struct VirtIOSerialPCI VirtIOSerialPCI;
>  typedef struct VirtIONetPCI VirtIONetPCI;
>  typedef struct VHostSCSIPCI VHostSCSIPCI;
> +typedef struct VHostUserSCSIPCI VHostUserSCSIPCI;
>  typedef struct VirtIORngPCI VirtIORngPCI;
>  typedef struct VirtIOInputPCI VirtIOInputPCI;
>  typedef struct VirtIOInputHIDPCI VirtIOInputHIDPCI;
> @@ -212,6 +216,17 @@ struct VHostSCSIPCI {
>  };
>  #endif
>  
> +#ifdef CONFIG_VHOST_USER_SCSI
> +#define TYPE_VHOST_USER_SCSI_PCI "vhost-user-scsi-pci"
> +#define VHOST_USER_SCSI_PCI(obj) \
> +        OBJECT_CHECK(VHostUserSCSIPCI, (obj), TYPE_VHOST_USER_SCSI_PCI)
> +
> +struct VHostUserSCSIPCI {
> +    VirtIOPCIProxy parent_obj;
> +    VHostUserSCSI vdev;
> +};
> +#endif
> +
>  /*
>   * virtio-blk-pci: This extends VirtioPCIProxy.
>   */
> diff --git a/include/hw/virtio/vhost-user-scsi.h b/include/hw/virtio/vhost-user-scsi.h
> new file mode 100644
> index 0000000..4a16181
> --- /dev/null
> +++ b/include/hw/virtio/vhost-user-scsi.h
> @@ -0,0 +1,45 @@
> +/*
> + * vhost-user-scsi host device
> + *
> + * Copyright (c) 2016 Nutanix Inc. All rights reserved.
> + *
> + * Author:
> + *  Felipe Franciosi <felipe@nutanix.com>
> + *
> + * This file is largely based on "vhost-scsi.h" by:
> + *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.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.
> + *
> + */
> +
> +#ifndef VHOST_USER_SCSI_H
> +#define VHOST_USER_SCSI_H
> +
> +#include "qemu-common.h"
> +#include "hw/qdev.h"
> +#include "hw/virtio/virtio-scsi.h"
> +#include "hw/virtio/vhost.h"
> +
> +enum vhost_user_scsi_vq_list {
> +    VHOST_USER_SCSI_VQ_CONTROL = 0,
> +    VHOST_USER_SCSI_VQ_EVENT = 1,
> +    VHOST_USER_SCSI_VQ_NUM_FIXED = 2,
> +};
> +
> +#define TYPE_VHOST_USER_SCSI "vhost-user-scsi"
> +#define VHOST_USER_SCSI(obj) \
> +        OBJECT_CHECK(VHostUserSCSI, (obj), TYPE_VHOST_USER_SCSI)
> +
> +typedef struct VHostUserSCSI {
> +    VirtIOSCSICommon parent_obj;
> +
> +    struct vhost_dev dev;
> +    int32_t bootindex;
> +    int channel;
> +    int target;
> +    int lun;
> +} VHostUserSCSI;
> +
> +#endif /* VHOST_USER_SCSI_H */
> diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
> index a1e0cfb..4b97386 100644
> --- a/include/hw/virtio/virtio-scsi.h
> +++ b/include/hw/virtio/virtio-scsi.h
> @@ -21,6 +21,7 @@
>  #include "hw/virtio/virtio.h"
>  #include "hw/pci/pci.h"
>  #include "hw/scsi/scsi.h"
> +#include "sysemu/char.h"
>  #include "sysemu/iothread.h"
>  
>  #define TYPE_VIRTIO_SCSI_COMMON "virtio-scsi-common"
> @@ -53,6 +54,10 @@ struct VirtIOSCSIConf {
>      char *wwpn;
>      uint32_t boot_tpgt;
>      IOThread *iothread;
> +#ifdef CONFIG_VHOST_USER_SCSI
> +    CharBackend chardev;
> +    int32_t bootindex;
> +#endif
>  };
>  
>  struct VirtIOSCSI;
>