virtio-scsi: define dummy handle_output for vhost-scsi vqs

vhost userspace needn't to handle vq's notification from guest,
so define dummy handle_output callback for all vqs of vhost-scsi.

In some corner cases(such as when handling vq's reset from VM), virtio-pci
still trys to handle pending virtio-scsi events, then object check failure
inside virtio_scsi_handle_event() for vhost-scsi can be triggered.

The issue can be reproduced by 'rmmod virtio-scsi', 'system sleep' or reboot
inside VM.

Cc: qemu-stable@nongnu.org
Cc: Anthony Liguori <aliguori@amazon.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 3870c47..8c8c9d1 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -667,7 +667,9 @@ static struct SCSIBusInfo virtio_scsi_scsi_info = {
     .load_request = virtio_scsi_load_request,
 };
 
-void virtio_scsi_common_realize(DeviceState *dev, Error **errp)
+void virtio_scsi_common_realize(DeviceState *dev, Error **errp,
+                                HandleOutput ctrl, HandleOutput evt,
+                                HandleOutput cmd)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOSCSICommon *s = VIRTIO_SCSI_COMMON(dev);
@@ -681,12 +683,12 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp)
     s->cdb_size = VIRTIO_SCSI_CDB_SIZE;
 
     s->ctrl_vq = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
-                                  virtio_scsi_handle_ctrl);
+                                  ctrl);
     s->event_vq = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
-                                   virtio_scsi_handle_event);
+                                   evt);
     for (i = 0; i < s->conf.num_queues; i++) {
         s->cmd_vqs[i] = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
-                                         virtio_scsi_handle_cmd);
+                                         cmd);
     }
 }
 
@@ -697,7 +699,9 @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
     static int virtio_scsi_id;
     Error *err = NULL;
 
-    virtio_scsi_common_realize(dev, &err);
+    virtio_scsi_common_realize(dev, &err, virtio_scsi_handle_ctrl,
+                               virtio_scsi_handle_event,
+                               virtio_scsi_handle_cmd);
     if (err != NULL) {
         error_propagate(errp, err);
         return;