qdev: add HotplugHandler->post_plug() callback

The ->pre_plug() callback is invoked before the device is realized.  The
->plug() callback is invoked when the device is being realized but
before it is reset.

This patch adds a ->post_plug() callback which is invoked after the
device has been reset.  This callback is needed by HotplugHandlers that
need to wait until after ->reset().
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20180716083732.3347-2-stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/core/hotplug.c

@@ -35,6 +35,16 @@ void hotplug_handler_plug(HotplugHandler *plug_handler,
     }
 }
 
+void hotplug_handler_post_plug(HotplugHandler *plug_handler,
+                               DeviceState *plugged_dev)
+{
+    HotplugHandlerClass *hdc = HOTPLUG_HANDLER_GET_CLASS(plug_handler);
+
+    if (hdc->post_plug) {
+        hdc->post_plug(plug_handler, plugged_dev);
+    }
+}
+
 void hotplug_handler_unplug_request(HotplugHandler *plug_handler,
                                     DeviceState *plugged_dev,
                                     Error **errp)

hw/core/qdev.c

@@ -867,6 +867,10 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
             device_reset(dev);
         }
         dev->pending_deleted_event = false;
+
+        if (hotplug_ctrl) {
+            hotplug_handler_post_plug(hotplug_ctrl, dev);
+        }
     } else if (!value && dev->realized) {
         Error **local_errp = NULL;
         QLIST_FOREACH(bus, &dev->child_bus, sibling) {

include/hw/hotplug.h

@@ -47,6 +47,8 @@ typedef void (*hotplug_fn)(HotplugHandler *plug_handler,
  * @parent: Opaque parent interface.
  * @pre_plug: pre plug callback called at start of device.realize(true)
  * @plug: plug callback called at end of device.realize(true).
+ * @post_plug: post plug callback called after device.realize(true) and device
+ *             reset
  * @unplug_request: unplug request callback.
  *                  Used as a means to initiate device unplug for devices that
  *                  require asynchronous unplug handling.
@@ -61,6 +63,7 @@ typedef struct HotplugHandlerClass {
     /* <public> */
     hotplug_fn pre_plug;
     hotplug_fn plug;
+    void (*post_plug)(HotplugHandler *plug_handler, DeviceState *plugged_dev);
     hotplug_fn unplug_request;
     hotplug_fn unplug;
 } HotplugHandlerClass;
@@ -83,6 +86,14 @@ void hotplug_handler_pre_plug(HotplugHandler *plug_handler,
                               DeviceState *plugged_dev,
                               Error **errp);
 
+/**
+ * hotplug_handler_post_plug:
+ *
+ * Call #HotplugHandlerClass.post_plug callback of @plug_handler.
+ */
+void hotplug_handler_post_plug(HotplugHandler *plug_handler,
+                               DeviceState *plugged_dev);
+
 /**
  * hotplug_handler_unplug_request:
  *