vhost-scsi: prevent using uninitialized vqs

There are 3 virtqueues (ctrl, event and cmd) for virtio scsi device,
but seabios will only set the physical address for the 3rd one (cmd).
Then in vhost_virtqueue_start(), virtio_queue_get_desc_addr()
will be 0 for ctrl and event vq.

In this case, ctrl and event vq are not initialized.
vhost_verify_ring_mappings may use uninitialized vhost_virtqueue
such that vhost_verify_ring_part_mapping returns ENOMEM.

When encountered this problem, we got the following logs:

    qemu-system-x86_64: Unable to map available ring for ring 0
    qemu-system-x86_64: Verify ring failure on region 0

Signed-off-by: Forrest Liu <forrestl@synology.com>
Signed-off-by: yuchenlin <yuchenlin@synology.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit e6cc11d64fc998c11a4dfcde8fda3fc33a74d844)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index 9c1bea8ff327e8ed1b678aff5943cf93fddbc91d..a5eb2800a20baf7117c48df37807e7e7d895746a 100644 (file)
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -183,7 +183,7 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
     }
 
     vsc->dev.nvqs = VHOST_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
-    vsc->dev.vqs = g_new(struct vhost_virtqueue, vsc->dev.nvqs);
+    vsc->dev.vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
     vsc->dev.vq_index = 0;
     vsc->dev.backend_features = 0;