[PATCH 10/13] vdpa: block migration if device has unsupported features

["Eugenio Pérez" <eperezma@redhat.com>]

A vdpa net device must initialize with SVQ in order to be migratable at
this moment, and initialization code verifies some conditions.  If the
device is not initialized with the x-svq parameter, it will not expose
_F_LOG so the vhost subsystem will block VM migration from its
initialization.

Next patches change this, so we need to verify migration conditions
differently.

QEMU only supports a subset of net features in SVQ, and it cannot
migrate state that cannot track or restore in the destination.  Add a
migration blocker if the device offer an unsupported feature.

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

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 309861e56c..a0c4d5de2c 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -952,6 +952,15 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
                                      iova_range);
         if (!ncs[i])
             goto err;
+
+        if (i == 0) {
+            VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, ncs[0]);
+
+            if (!s->vhost_vdpa.dev->migration_blocker) {
+                vhost_vdpa_net_valid_svq_features(features,
+                                        &s->vhost_vdpa.dev->migration_blocker);
+            }
+        }
     }
 
     if (has_cvq) {
-- 
2.31.1