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-rw-r--r--hw/s390x/virtio-ccw.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 8d140dc50f..4582e94ae7 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -1122,9 +1122,18 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
}
if (!virtio_ccw_rev_max(dev) && !virtio_legacy_allowed(vdev)) {
- error_setg(errp, "Invalid value of property max_rev "
- "(is %d expected >= 1)", virtio_ccw_rev_max(dev));
- return;
+ /*
+ * To avoid migration issues, we allow legacy mode when legacy
+ * check is disabled in the old machine types (< 5.1).
+ */
+ if (virtio_legacy_check_disabled(vdev)) {
+ warn_report("device requires revision >= 1, but for backward "
+ "compatibility max_revision=0 is allowed");
+ } else {
+ error_setg(errp, "Invalid value of property max_rev "
+ "(is %d expected >= 1)", virtio_ccw_rev_max(dev));
+ return;
+ }
}
if (virtio_get_num_queues(vdev) > VIRTIO_QUEUE_MAX) {