[v2,2/3] 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=...

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           | 198 ++++++++++++++++++++++++++++++++++++
 hw/virtio/virtio-pci.c              |  58 +++++++++++
 hw/virtio/virtio-pci.h              |  15 +++
 include/hw/virtio/vhost-user-scsi.h |  34 +++++++
 include/hw/virtio/virtio-scsi.h     |   5 +
 7 files changed, 321 insertions(+)
 create mode 100644 hw/scsi/vhost-user-scsi.c
 create mode 100644 include/hw/virtio/vhost-user-scsi.h

Hi

On Thu, Nov 10, 2016 at 5:50 PM Felipe Franciosi <felipe@nutanix.com> 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=...
>
>
Instead of adding a new device, have you investigated using vhost-scsi-pci
with a new vhost-user (chardev) option? I managed to do that with
virtio-input/gpu.

fwiw, in  vhost-user-gpu RFC series, I went a step further, and created a
"vhost-user-backend" object, which may not be a great idea, but simplify
some setup:

-object vhost-user-backend,id=vug,cmd="./vhost-user-gpu"
-device virtio-vga,virgl=true,vhost-user=vug

https://lists.nongnu.org/archive/html/qemu-devel/2016-06/msg01013.html

Once I get back to this RFC, I'll try to refine this idea, but feedback is
welcome.


> 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           | 198
> ++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-pci.c              |  58 +++++++++++
>  hw/virtio/virtio-pci.h              |  15 +++
>  include/hw/virtio/vhost-user-scsi.h |  34 +++++++
>  include/hw/virtio/virtio-scsi.h     |   5 +
>  7 files changed, 321 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 fd6f898..8fd8678 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"
>  colo="yes"
> @@ -678,6 +679,7 @@ 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"
>  ;;
> @@ -1024,6 +1026,10 @@ 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"
> @@ -5048,6 +5054,7 @@ 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    $trace_backends"
>  if have_backend "simple"; then
> @@ -5433,6 +5440,9 @@ fi
>  if test "$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" >> $config_host_mak
>  fi
> diff --git a/hw/scsi/Makefile.objs b/hw/scsi/Makefile.objs
> index 54d8754..b188f72 100644
> --- a/hw/scsi/Makefile.objs
> +++ b/hw/scsi/Makefile.objs
> @@ -11,4 +11,5 @@ obj-$(CONFIG_PSERIES) += spapr_vscsi.o
>  ifeq ($(CONFIG_VIRTIO),y)
>  obj-y += virtio-scsi.o virtio-scsi-dataplane.o
>  obj-$(CONFIG_VHOST_SCSI) += vhost-scsi-common.o vhost-scsi.o
> +obj-$(CONFIG_VHOST_USER_SCSI) += vhost-scsi-common.o 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..6bb3a9c
> --- /dev/null
> +++ b/hw/scsi/vhost-user-scsi.c
> @@ -0,0 +1,198 @@
> +/*
> + * 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 "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 void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t status)
> +{
> +    VHostUserSCSI *s = (VHostUserSCSI *)vdev;
> +    VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
> +    bool start = (status & VIRTIO_CONFIG_S_DRIVER_OK) && vdev->vm_running;
> +
> +    if (vsc->dev.started == start) {
> +        return;
> +    }
> +
> +    if (start) {
> +        int ret;
> +
> +        ret = vhost_scsi_common_start(vsc);
> +        if (ret < 0) {
> +            error_report("unable to start vhost-user-scsi: %s",
> strerror(-ret));
> +            exit(1);
> +        }
> +    } else {
> +        vhost_scsi_common_stop(vsc);
> +    }
> +}
> +
> +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);
> +    VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
> +    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;
> +    }
> +
> +    vsc->dev.nvqs = 2 + vs->conf.num_queues;
> +    vsc->dev.vqs = g_new(struct vhost_virtqueue, vsc->dev.nvqs);
> +    vsc->dev.vq_index = 0;
> +    vsc->dev.backend_features = 0;
> +
> +    ret = vhost_dev_init(&vsc->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 */
> +    vsc->channel = 0;
> +    vsc->lun = 0;
> +    vsc->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);
> +    VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
> +
> +    /* This will stop the vhost backend. */
> +    vhost_user_scsi_set_status(vdev, 0);
> +
> +    vhost_dev_cleanup(&vsc->dev);
> +    g_free(vsc->dev.vqs);
> +
> +    virtio_scsi_common_unrealize(dev, errp);
> +}
> +
> +static Property vhost_user_scsi_properties[] = {
> +    DEFINE_PROP_CHR("chardev", VirtIOSCSICommon, conf.chardev),
> +    DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0),
> +    DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues,
> 1),
> +    DEFINE_PROP_UINT32("max_sectors", VirtIOSCSICommon, conf.max_sectors,
> +                       0xFFFF),
> +    DEFINE_PROP_UINT32("cmd_per_lun", VirtIOSCSICommon, 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_scsi_common_get_features;
> +    vdc->set_config = vhost_scsi_common_set_config;
> +    vdc->set_status = vhost_user_scsi_set_status;
> +    fwc->get_dev_path = vhost_scsi_common_get_fw_dev_path;
> +}
> +
> +static void vhost_user_scsi_instance_init(Object *obj)
> +{
> +    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(obj);
> +    VHostSCSICommon *vsc = VHOST_SCSI_COMMON(obj);
> +
> +    vsc->feature_bits = user_feature_bits;
> +
> +    // Add the bootindex property for this object
> +    device_add_bootindex_property(obj, &vsc->bootindex, "bootindex", NULL,
> +                                  DEVICE(vsc), 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_VHOST_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 62001b4..7cc63b5 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -2075,6 +2075,61 @@ 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
> @@ -2551,6 +2606,9 @@ 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 b2a996f..9dd02f4 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -33,6 +33,9 @@
>  #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
> @@ -44,6 +47,7 @@ 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;
> @@ -213,6 +217,17 @@ 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..9694bd9
> --- /dev/null
> +++ b/include/hw/virtio/vhost-user-scsi.h
> @@ -0,0 +1,34 @@
> +/*
> + * 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"
> +#include "hw/virtio/vhost-scsi-common.h"
> +
> +#define TYPE_VHOST_USER_SCSI "vhost-user-scsi"
> +#define VHOST_USER_SCSI(obj) \
> +        OBJECT_CHECK(VHostUserSCSI, (obj), TYPE_VHOST_USER_SCSI)
> +
> +typedef struct VHostUserSCSI {
> +    VHostSCSICommon parent_obj;
> +} VHostUserSCSI;
> +
> +#endif /* VHOST_USER_SCSI_H */
> diff --git a/include/hw/virtio/virtio-scsi.h
> b/include/hw/virtio/virtio-scsi.h
> index f52ce7a..5d8eda4 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 *vhostfd;
>      char *wwpn;
>  #endif
> +#ifdef CONFIG_VHOST_USER_SCSI
> +    CharBackend chardev;
> +    int32_t bootindex;
> +#endif
>      uint32_t boot_tpgt;
>      IOThread *iothread;
>  };
> --
> 1.9.4
>
>
> --
Marc-André Lureau