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, 7 insertions, 1 deletions

diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index 668bafa..cc8df4e 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -196,6 +196,10 @@ static void vhost_scsi_set_status(VirtIODevice *vdev, uint8_t val)
     }
 }
 
+static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+}
+
 static void vhost_scsi_realize(DeviceState *dev, Error **errp)
 {
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
@@ -217,7 +221,9 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
         }
     }
 
-    virtio_scsi_common_realize(dev, &err);
+    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;