virtio-net: unbreak self announcement and guest offloads after migration

After commit 019a3edb ("virtio: make
features 64bit wide"). Device's guest_features was actually set after
vdc->load(). This breaks the assumption that device specific load()
function can check guest_features. For virtio-net, self announcement
and guest offloads won't work after migration.

Fixing this by defer them to virtio_net_load() where guest_features
were guaranteed to be set. Other virtio devices looks fine.

Fixes: 019a3edb
       ("virtio: make features 64bit wide")
Cc: qemu-stable@nongnu.org
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>

(cherry picked from commit 1f8828ef)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

hw/net/virtio-net.c

@@ -1462,11 +1462,33 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIONet *n = opaque;
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
+    int ret;
 
     if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
         return -EINVAL;
 
-    return virtio_load(vdev, f, version_id);
+    ret = virtio_load(vdev, f, version_id);
+    if (ret) {
+        return ret;
+    }
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
+        n->curr_guest_offloads = qemu_get_be64(f);
+    } else {
+        n->curr_guest_offloads = virtio_net_supported_guest_offloads(n);
+    }
+
+    if (peer_has_vnet_hdr(n)) {
+        virtio_net_apply_guest_offloads(n);
+    }
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
+        virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
+        n->announce_counter = SELF_ANNOUNCE_ROUNDS;
+        timer_mod(n->announce_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL));
+    }
+
+    return 0;
 }
 
 static int virtio_net_load_device(VirtIODevice *vdev, QEMUFile *f,
@@ -1563,16 +1585,6 @@ static int virtio_net_load_device(VirtIODevice *vdev, QEMUFile *f,
         }
     }
 
-    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
-        n->curr_guest_offloads = qemu_get_be64(f);
-    } else {
-        n->curr_guest_offloads = virtio_net_supported_guest_offloads(n);
-    }
-
-    if (peer_has_vnet_hdr(n)) {
-        virtio_net_apply_guest_offloads(n);
-    }
-
     virtio_net_set_queues(n);
 
     /* Find the first multicast entry in the saved MAC filter */
@@ -1590,12 +1602,6 @@ static int virtio_net_load_device(VirtIODevice *vdev, QEMUFile *f,
         qemu_get_subqueue(n->nic, i)->link_down = link_down;
     }
 
-    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
-        virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
-        n->announce_counter = SELF_ANNOUNCE_ROUNDS;
-        timer_mod(n->announce_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL));
-    }
-
     return 0;
 }