3 files changed, 22 insertions, 2 deletions

diff --git a/hw/hw.h b/hw/hw.h
index 2d397243d1..fc2d1849d7 100644
--- a/hw/hw.h
+++ b/hw/hw.h
@@ -758,5 +758,9 @@ extern void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                                void *opaque);
 extern int vmstate_register(int instance_id, const VMStateDescription *vmsd,
                             void *base);
+extern int vmstate_register_with_alias_id(int instance_id,
+                                          const VMStateDescription *vmsd,
+                                          void *base, int alias_id,
+                                          int required_for_version);
 void vmstate_unregister(const VMStateDescription *vmsd, void *opaque);
 #endif
diff --git a/hw/qdev.c b/hw/qdev.c
index d3bf0fa43d..af17486976 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -93,6 +93,7 @@ static DeviceState *qdev_create_from_info(BusState *bus, DeviceInfo *info)
         assert(bus->allow_hotplug);
         dev->hotplugged = 1;
     }
+    dev->instance_id_alias = -1;
     dev->state = DEV_STATE_CREATED;
     return dev;
 }
@@ -278,12 +279,23 @@ int qdev_init(DeviceState *dev)
         return rc;
     }
     qemu_register_reset(qdev_reset, dev);
-    if (dev->info->vmsd)
-        vmstate_register(-1, dev->info->vmsd, dev);
+    if (dev->info->vmsd) {
+        vmstate_register_with_alias_id(-1, dev->info->vmsd, dev,
+                                       dev->instance_id_alias,
+                                       dev->alias_required_for_version);
+    }
     dev->state = DEV_STATE_INITIALIZED;
     return 0;
 }
 
+void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
+                                 int required_for_version)
+{
+    assert(dev->state == DEV_STATE_CREATED);
+    dev->instance_id_alias = alias_id;
+    dev->alias_required_for_version = required_for_version;
+}
+
 int qdev_unplug(DeviceState *dev)
 {
     if (!dev->parent_bus->allow_hotplug) {
diff --git a/hw/qdev.h b/hw/qdev.h
index d8fbc739a0..a44060e54c 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -44,6 +44,8 @@ struct DeviceState {
     QLIST_HEAD(, BusState) child_bus;
     int num_child_bus;
     QLIST_ENTRY(DeviceState) sibling;
+    int instance_id_alias;
+    int alias_required_for_version;
 };
 
 typedef void (*bus_dev_printfn)(Monitor *mon, DeviceState *dev, int indent);
@@ -112,6 +114,8 @@ int qdev_device_help(QemuOpts *opts);
 DeviceState *qdev_device_add(QemuOpts *opts);
 int qdev_init(DeviceState *dev) QEMU_WARN_UNUSED_RESULT;
 void qdev_init_nofail(DeviceState *dev);
+void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
+                                 int required_for_version);
 int qdev_unplug(DeviceState *dev);
 void qdev_free(DeviceState *dev);
 int qdev_simple_unplug_cb(DeviceState *dev);