3 files changed, 44 insertions, 18 deletions
diff --git a/migration/migration.c b/migration/migration.c
index 5c9285125a..ed11c1fb53 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -78,13 +78,6 @@ static NotifierList migration_state_notifiers =
 
 static bool deferred_incoming;
 
-/*
- * Current state of incoming postcopy; note this is not part of
- * MigrationIncomingState since it's state is used during cleanup
- * at the end as MIS is being freed.
- */
-static PostcopyState incoming_postcopy_state;
-
 /* When we add fault tolerance, we could have several
    migrations at once.  For now we don't need to add
    dynamic creation of migration */
@@ -2098,14 +2091,3 @@ void migrate_fd_connect(MigrationState *s)
     s->migration_thread_running = true;
 }
 
-PostcopyState  postcopy_state_get(void)
-{
-    return atomic_mb_read(&incoming_postcopy_state);
-}
-
-/* Set the state and return the old state */
-PostcopyState postcopy_state_set(PostcopyState new_state)
-{
-    return atomic_xchg(&incoming_postcopy_state, new_state);
-}
-
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index cdadaf6578..a0489f6542 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -784,3 +784,21 @@ void postcopy_discard_send_finish(MigrationState *ms, PostcopyDiscardState *pds)
 
     g_free(pds);
 }
+
+/*
+ * Current state of incoming postcopy; note this is not part of
+ * MigrationIncomingState since it's state is used during cleanup
+ * at the end as MIS is being freed.
+ */
+static PostcopyState incoming_postcopy_state;
+
+PostcopyState  postcopy_state_get(void)
+{
+    return atomic_mb_read(&incoming_postcopy_state);
+}
+
+/* Set the state and return the old state */
+PostcopyState postcopy_state_set(PostcopyState new_state)
+{
+    return atomic_xchg(&incoming_postcopy_state, new_state);
+}
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 4c25f03be2..52d51e8007 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -81,6 +81,28 @@ int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
                              size_t pagesize);
 
+/* The current postcopy state is read/set by postcopy_state_get/set
+ * which update it atomically.
+ * The state is updated as postcopy messages are received, and
+ * in general only one thread should be writing to the state at any one
+ * time, initially the main thread and then the listen thread;
+ * Corner cases are where either thread finishes early and/or errors.
+ * The state is checked as messages are received to ensure that
+ * the source is sending us messages in the correct order.
+ * The state is also used by the RAM reception code to know if it
+ * has to place pages atomically, and the cleanup code at the end of
+ * the main thread to know if it has to delay cleanup until the end
+ * of postcopy.
+ */
+typedef enum {
+    POSTCOPY_INCOMING_NONE = 0,  /* Initial state - no postcopy */
+    POSTCOPY_INCOMING_ADVISE,
+    POSTCOPY_INCOMING_DISCARD,
+    POSTCOPY_INCOMING_LISTENING,
+    POSTCOPY_INCOMING_RUNNING,
+    POSTCOPY_INCOMING_END
+} PostcopyState;
+
 /*
  * Allocate a page of memory that can be mapped at a later point in time
  * using postcopy_place_page
@@ -88,4 +110,8 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
  */
 void *postcopy_get_tmp_page(MigrationIncomingState *mis);
 
+PostcopyState postcopy_state_get(void);
+/* Set the state and return the old state */
+PostcopyState postcopy_state_set(PostcopyState new_state);
+
 #endif