[Qemu-devel] [PATCH 1/1] dataplane: bail out on unsupported transport

[Cornelia Huck <cornelia.huck@de.ibm.com>]

If the virtio transport does not support notifiers (like s390-virtio),
we can't use dataplane. Bail out early and let the user know what is
wrong.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/block/dataplane/virtio-blk.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index e49c253..e0c653f 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -354,6 +354,8 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
     VirtIOBlockDataPlane *s;
     int fd;
     Error *local_err = NULL;
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 
     *dataplane = NULL;
 
@@ -361,6 +363,14 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
         return;
     }
 
+    /* Don't try if transport does not support notifiers. */
+    if (!k->set_guest_notifiers || !k->set_host_notifier) {
+        error_setg(errp,
+                   "device is incompatible with x-data-plane "
+                   "(transport does not support notifiers)");
+        return;
+    }
+
     if (blk->scsi) {
         error_setg(errp,
                    "device is incompatible with x-data-plane, use scsi=off");
-- 
1.8.5.5