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-rw-r--r--migration/migration.c76
-rw-r--r--qapi/migration.json4
2 files changed, 60 insertions, 20 deletions
diff --git a/migration/migration.c b/migration/migration.c
index 038fae93ab..4ab637a1fe 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -577,6 +577,7 @@ static bool migration_is_setup_or_active(int state)
     case MIGRATION_STATUS_ACTIVE:
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
     case MIGRATION_STATUS_POSTCOPY_PAUSED:
+    case MIGRATION_STATUS_POSTCOPY_RECOVER:
     case MIGRATION_STATUS_SETUP:
     case MIGRATION_STATUS_PRE_SWITCHOVER:
     case MIGRATION_STATUS_DEVICE:
@@ -658,6 +659,7 @@ static void fill_source_migration_info(MigrationInfo *info)
     case MIGRATION_STATUS_PRE_SWITCHOVER:
     case MIGRATION_STATUS_DEVICE:
     case MIGRATION_STATUS_POSTCOPY_PAUSED:
+    case MIGRATION_STATUS_POSTCOPY_RECOVER:
          /* TODO add some postcopy stats */
         info->has_status = true;
         info->has_total_time = true;
@@ -2318,6 +2320,13 @@ typedef enum MigThrError {
     MIG_THR_ERR_FATAL = 2,
 } MigThrError;
 
+/* Return zero if success, or <0 for error */
+static int postcopy_do_resume(MigrationState *s)
+{
+    /* TODO: do the resume logic */
+    return 0;
+}
+
 /*
  * We don't return until we are in a safe state to continue current
  * postcopy migration.  Returns MIG_THR_ERR_RECOVERED if recovered, or
@@ -2326,29 +2335,55 @@ typedef enum MigThrError {
 static MigThrError postcopy_pause(MigrationState *s)
 {
     assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
-    migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
-                      MIGRATION_STATUS_POSTCOPY_PAUSED);
 
-    /* Current channel is possibly broken. Release it. */
-    assert(s->to_dst_file);
-    qemu_file_shutdown(s->to_dst_file);
-    qemu_fclose(s->to_dst_file);
-    s->to_dst_file = NULL;
+    while (true) {
+        migrate_set_state(&s->state, s->state,
+                          MIGRATION_STATUS_POSTCOPY_PAUSED);
 
-    error_report("Detected IO failure for postcopy. "
-                 "Migration paused.");
+        /* Current channel is possibly broken. Release it. */
+        assert(s->to_dst_file);
+        qemu_file_shutdown(s->to_dst_file);
+        qemu_fclose(s->to_dst_file);
+        s->to_dst_file = NULL;
 
-    /*
-     * We wait until things fixed up. Then someone will setup the
-     * status back for us.
-     */
-    while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
-        qemu_sem_wait(&s->postcopy_pause_sem);
-    }
+        error_report("Detected IO failure for postcopy. "
+                     "Migration paused.");
 
-    trace_postcopy_pause_continued();
+        /*
+         * We wait until things fixed up. Then someone will setup the
+         * status back for us.
+         */
+        while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
+            qemu_sem_wait(&s->postcopy_pause_sem);
+        }
+
+        if (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
+            /* Woken up by a recover procedure. Give it a shot */
 
-    return MIG_THR_ERR_RECOVERED;
+            /*
+             * Firstly, let's wake up the return path now, with a new
+             * return path channel.
+             */
+            qemu_sem_post(&s->postcopy_pause_rp_sem);
+
+            /* Do the resume logic */
+            if (postcopy_do_resume(s) == 0) {
+                /* Let's continue! */
+                trace_postcopy_pause_continued();
+                return MIG_THR_ERR_RECOVERED;
+            } else {
+                /*
+                 * Something wrong happened during the recovery, let's
+                 * pause again. Pause is always better than throwing
+                 * data away.
+                 */
+                continue;
+            }
+        } else {
+            /* This is not right... Time to quit. */
+            return MIG_THR_ERR_FATAL;
+        }
+    }
 }
 
 static MigThrError migration_detect_error(MigrationState *s)
@@ -2668,7 +2703,10 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
     }
 
     if (resume) {
-        /* TODO: do the resume logic */
+        /* Wakeup the main migration thread to do the recovery */
+        migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
+                          MIGRATION_STATUS_POSTCOPY_RECOVER);
+        qemu_sem_post(&s->postcopy_pause_sem);
         return;
     }
 
diff --git a/qapi/migration.json b/qapi/migration.json
index b8ca60ac43..4e8e61ceef 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -91,6 +91,8 @@
 #
 # @postcopy-paused: during postcopy but paused. (since 2.13)
 #
+# @postcopy-recover: trying to recover from a paused postcopy. (since 2.13)
+#
 # @completed: migration is finished.
 #
 # @failed: some error occurred during migration process.
@@ -109,7 +111,7 @@
 { 'enum': 'MigrationStatus',
   'data': [ 'none', 'setup', 'cancelling', 'cancelled',
             'active', 'postcopy-active', 'postcopy-paused',
-            'completed', 'failed', 'colo',
+            'postcopy-recover', 'completed', 'failed', 'colo',
             'pre-switchover', 'device' ] }
 
 ##