Next patches enable devices to be migrated even if vdpa netdev has not
been started with x-svq. However, not all devices are migratable, so we
need to block migration if we detect that.

Block migration if we detect the device expose a feature SVQ does not
know how to work with.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/vhost-vdpa.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 3a85f9f1ed..9b8c22bda3 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -461,6 +461,15 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
         if (!(backend_features & BIT_ULL(VHOST_BACKEND_F_SUSPEND))) {
             error_setg(&dev->migration_blocker,
                 "vhost-vdpa backend lacks VHOST_BACKEND_F_SUSPEND feature.");
+        } else {
+            /* We don't have dev->features yet */
+            uint64_t features;
+            ret = vhost_vdpa_get_dev_features(dev, &features);
+            if (unlikely(ret)) {
+                error_setg_errno(errp, -ret, "Could not get device features");
+                return ret;
+            }
+            vhost_svq_valid_features(features, &dev->migration_blocker);
         }
     }
 
-- 
2.31.1