1 files changed, 40 insertions, 0 deletions

diff --git a/softmmu/runstate.c b/softmmu/runstate.c
index f3bd862818..1652ed0439 100644
--- a/softmmu/runstate.c
+++ b/softmmu/runstate.c
@@ -271,6 +271,7 @@ void qemu_system_vmstop_request(RunState state)
 }
 struct VMChangeStateEntry {
     VMChangeStateHandler *cb;
+    VMChangeStateHandler *prepare_cb;
     void *opaque;
     QTAILQ_ENTRY(VMChangeStateEntry) entries;
     int priority;
@@ -294,11 +295,38 @@ static QTAILQ_HEAD(, VMChangeStateEntry) vm_change_state_head =
 VMChangeStateEntry *qemu_add_vm_change_state_handler_prio(
         VMChangeStateHandler *cb, void *opaque, int priority)
 {
+    return qemu_add_vm_change_state_handler_prio_full(cb, NULL, opaque,
+                                                      priority);
+}
+
+/**
+ * qemu_add_vm_change_state_handler_prio_full:
+ * @cb: the main callback to invoke
+ * @prepare_cb: a callback to invoke before the main callback
+ * @opaque: user data passed to the callbacks
+ * @priority: low priorities execute first when the vm runs and the reverse is
+ *            true when the vm stops
+ *
+ * Register a main callback function and an optional prepare callback function
+ * that are invoked when the vm starts or stops running. The main callback and
+ * the prepare callback are called in two separate phases: First all prepare
+ * callbacks are called and only then all main callbacks are called. As its
+ * name suggests, the prepare callback can be used to do some preparatory work
+ * before invoking the main callback.
+ *
+ * Returns: an entry to be freed using qemu_del_vm_change_state_handler()
+ */
+VMChangeStateEntry *
+qemu_add_vm_change_state_handler_prio_full(VMChangeStateHandler *cb,
+                                           VMChangeStateHandler *prepare_cb,
+                                           void *opaque, int priority)
+{
     VMChangeStateEntry *e;
     VMChangeStateEntry *other;
 
     e = g_malloc0(sizeof(*e));
     e->cb = cb;
+    e->prepare_cb = prepare_cb;
     e->opaque = opaque;
     e->priority = priority;
 
@@ -334,10 +362,22 @@ void vm_state_notify(bool running, RunState state)
 
     if (running) {
         QTAILQ_FOREACH_SAFE(e, &vm_change_state_head, entries, next) {
+            if (e->prepare_cb) {
+                e->prepare_cb(e->opaque, running, state);
+            }
+        }
+
+        QTAILQ_FOREACH_SAFE(e, &vm_change_state_head, entries, next) {
             e->cb(e->opaque, running, state);
         }
     } else {
         QTAILQ_FOREACH_REVERSE_SAFE(e, &vm_change_state_head, entries, next) {
+            if (e->prepare_cb) {
+                e->prepare_cb(e->opaque, running, state);
+            }
+        }
+
+        QTAILQ_FOREACH_REVERSE_SAFE(e, &vm_change_state_head, entries, next) {
             e->cb(e->opaque, running, state);
         }
     }