virtio-serial: don't migrate the config space

The device configuration is set at realize time and never changes. It
should not be migrated as it is done today. For the sake of compatibility,
let's just skip them at load time.
Signed-off-by: NAlexander Graf <agraf@suse.de>
[ added missing casts to uint16_t *,
  added From, SoB and commit message,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/char/virtio-serial-bus.c

@@ -663,6 +663,7 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
     uint32_t max_nr_ports, nr_active_ports, ports_map;
     unsigned int i;
     int ret;
+    uint32_t tmp;
 
     if (version_id > 3) {
         return -EINVAL;
@@ -678,17 +679,12 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
         return 0;
     }
 
-    /* The config space */
-    qemu_get_be16s(f, &s->config.cols);
-    qemu_get_be16s(f, &s->config.rows);
-
-    qemu_get_be32s(f, &max_nr_ports);
-    tswap32s(&max_nr_ports);
-    if (max_nr_ports > tswap32(s->config.max_nr_ports)) {
-        /* Source could have had more ports than us. Fail migration. */
-        return -EINVAL;
-    }
+    /* Unused */
+    qemu_get_be16s(f, (uint16_t *) &tmp);
+    qemu_get_be16s(f, (uint16_t *) &tmp);
+    qemu_get_be32s(f, &tmp);
 
+    max_nr_ports = tswap32(s->config.max_nr_ports);
     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
         qemu_get_be32s(f, &ports_map);