vhost-user-scsi: 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, 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>
Message-Id: <1488479153-21203-4-git-send-email-felipe@nutanix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 206 insertions, 1 deletions

diff --git a/hw/scsi/Makefile.objs b/hw/scsi/Makefile.objs
index 54d8754e9a..b188f7242b 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-scsi-common.c b/hw/scsi/vhost-scsi-common.c
index e41c0314db..d434b3e99a 100644
--- a/hw/scsi/vhost-scsi-common.c
+++ b/hw/scsi/vhost-scsi-common.c
@@ -16,7 +16,6 @@
  */
 
 #include "qemu/osdep.h"
-#include <linux/vhost.h>
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "migration/migration.h"
diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
new file mode 100644
index 0000000000..500fa6a067
--- /dev/null
+++ b/hw/scsi/vhost-user-scsi.c
@@ -0,0 +1,205 @@
+/*
+ * 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 "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 "chardev/char-fe.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_realize(DeviceState *dev, Error **errp)
+{
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
+    VHostUserSCSI *s = VHOST_USER_SCSI(dev);
+    VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
+    Error *err = NULL;
+    int ret;
+
+    if (!vs->conf.chardev.chr) {
+        error_setg(errp, "vhost-user-scsi: missing chardev");
+        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);
+        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;
+}
+
+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 uint64_t vhost_user_scsi_get_features(VirtIODevice *vdev,
+                                             uint64_t features, Error **errp)
+{
+    VHostUserSCSI *s = VHOST_USER_SCSI(vdev);
+
+    /* Turn on predefined features supported by this device */
+    features |= s->host_features;
+
+    return vhost_scsi_common_get_features(vdev, features, 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_BIT64("hotplug", VHostUserSCSI, host_features,
+                                                VIRTIO_SCSI_F_HOTPLUG,
+                                                true),
+    DEFINE_PROP_BIT64("param_change", VHostUserSCSI, host_features,
+                                                     VIRTIO_SCSI_F_CHANGE,
+                                                     true),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static const VMStateDescription vmstate_vhost_scsi = {
+    .name = "virtio-scsi",
+    .minimum_version_id = 1,
+    .version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_VIRTIO_DEVICE,
+        VMSTATE_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;
+    dc->vmsd = &vmstate_vhost_scsi;
+    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_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)
+{
+    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);
+}
+
+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)