virtio-blk: Fix migration of queued requests

in_sg[].iovec and out_sg[].ioved are pointer to (source) host memory and
therefore invalid after migration. When loading the device state we must
create a new mapping on the destination host.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
(cherry picked from commit b6a4805b)

hw/virtio-blk.c

@@ -480,6 +480,11 @@ static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
         qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
         req->next = s->rq;
         s->rq = req;
+
+        virtqueue_map_sg(req->elem.in_sg, req->elem.in_addr,
+            req->elem.in_num, 1);
+        virtqueue_map_sg(req->elem.out_sg, req->elem.out_addr,
+            req->elem.out_num, 0);
     }
 
     return 0;