vdpa: set backend capabilities at vhost_vdpa_init

The backend does not reset them until the vdpa file descriptor is closed
so there is no harm in doing it only once.

This allows the destination of a live migration to premap memory in
batches, using VHOST_BACKEND_F_IOTLB_BATCH.

Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
Message-Id: <20250522145839.59974-4-jonah.palmer@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 6b242ca56aca818d6b7dafb09ad7f23b7f14594c..e9826ede2cd27a29dac1a43da2b0b36e1c281a57 100644 (file)
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -634,6 +634,12 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
     v->dev = dev;
     dev->opaque =  opaque ;
     v->shared->listener = vhost_vdpa_memory_listener;
+
+    ret = vhost_vdpa_set_backend_cap(dev);
+    if (unlikely(ret != 0)) {
+        return ret;
+    }
+
     vhost_vdpa_init_svq(dev, v);
 
     error_propagate(&dev->migration_blocker, v->migration_blocker);
@@ -1563,7 +1569,6 @@ const VhostOps vdpa_ops = {
         .vhost_set_vring_kick = vhost_vdpa_set_vring_kick,
         .vhost_set_vring_call = vhost_vdpa_set_vring_call,
         .vhost_get_features = vhost_vdpa_get_features,
-        .vhost_set_backend_cap = vhost_vdpa_set_backend_cap,
         .vhost_set_owner = vhost_vdpa_set_owner,
         .vhost_set_vring_endian = NULL,
         .vhost_backend_memslots_limit = vhost_vdpa_memslots_limit,