1 files changed, 108 insertions, 21 deletions

diff --git a/migration/migration.c b/migration/migration.c
index 98429dc843..62761d5705 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -104,6 +104,9 @@ enum mig_rp_message_type {
 static MigrationState *current_migration;
 
 static bool migration_object_check(MigrationState *ms, Error **errp);
+static int migration_maybe_pause(MigrationState *s,
+                                 int *current_active_state,
+                                 int new_state);
 
 void migration_object_init(void)
 {
@@ -526,6 +529,8 @@ static bool migration_is_setup_or_active(int state)
     case MIGRATION_STATUS_ACTIVE:
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
     case MIGRATION_STATUS_SETUP:
+    case MIGRATION_STATUS_PRE_SWITCHOVER:
+    case MIGRATION_STATUS_DEVICE:
         return true;
 
     default:
@@ -600,6 +605,8 @@ MigrationInfo *qmp_query_migrate(Error **errp)
     case MIGRATION_STATUS_ACTIVE:
     case MIGRATION_STATUS_CANCELLING:
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
+    case MIGRATION_STATUS_PRE_SWITCHOVER:
+    case MIGRATION_STATUS_DEVICE:
          /* TODO add some postcopy stats */
         info->has_status = true;
         info->has_total_time = true;
@@ -865,6 +872,12 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
     if (params->has_block_incremental) {
         dest->block_incremental = params->block_incremental;
     }
+    if (params->has_x_multifd_channels) {
+        dest->x_multifd_channels = params->x_multifd_channels;
+    }
+    if (params->has_x_multifd_page_count) {
+        dest->x_multifd_page_count = params->x_multifd_page_count;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params)
@@ -1071,19 +1084,30 @@ static void migrate_fd_cleanup(void *opaque)
                           MIGRATION_STATUS_CANCELLED);
     }
 
+    if (s->error) {
+        /* It is used on info migrate.  We can't free it */
+        error_report_err(error_copy(s->error));
+    }
     notifier_list_notify(&migration_state_notifiers, s);
     block_cleanup_parameters(s);
 }
 
+void migrate_set_error(MigrationState *s, const Error *error)
+{
+    qemu_mutex_lock(&s->error_mutex);
+    if (!s->error) {
+        s->error = error_copy(error);
+    }
+    qemu_mutex_unlock(&s->error_mutex);
+}
+
 void migrate_fd_error(MigrationState *s, const Error *error)
 {
     trace_migrate_fd_error(error_get_pretty(error));
     assert(s->to_dst_file == NULL);
     migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
                       MIGRATION_STATUS_FAILED);
-    if (!s->error) {
-        s->error = error_copy(error);
-    }
+    migrate_set_error(s, error);
     notifier_list_notify(&migration_state_notifiers, s);
     block_cleanup_parameters(s);
 }
@@ -1104,6 +1128,10 @@ static void migrate_fd_cancel(MigrationState *s)
         if (!migration_is_setup_or_active(old_state)) {
             break;
         }
+        /* If the migration is paused, kick it out of the pause */
+        if (old_state == MIGRATION_STATUS_PRE_SWITCHOVER) {
+            qemu_sem_post(&s->pause_sem);
+        }
         migrate_set_state(&s->state, old_state, MIGRATION_STATUS_CANCELLING);
     } while (s->state != MIGRATION_STATUS_CANCELLING);
 
@@ -1183,6 +1211,8 @@ bool migration_is_idle(void)
     case MIGRATION_STATUS_ACTIVE:
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
     case MIGRATION_STATUS_COLO:
+    case MIGRATION_STATUS_PRE_SWITCHOVER:
+    case MIGRATION_STATUS_DEVICE:
         return false;
     case MIGRATION_STATUS__MAX:
         g_assert_not_reached();
@@ -1362,29 +1392,24 @@ void qmp_migrate_cancel(Error **errp)
     migrate_fd_cancel(migrate_get_current());
 }
 
-void qmp_migrate_set_cache_size(int64_t value, Error **errp)
+void qmp_migrate_continue(MigrationStatus state, Error **errp)
 {
     MigrationState *s = migrate_get_current();
-    int64_t new_size;
-
-    /* Check for truncation */
-    if (value != (size_t)value) {
-        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
-                   "exceeding address space");
+    if (s->state != state) {
+        error_setg(errp,  "Migration not in expected state: %s",
+                   MigrationStatus_str(s->state));
         return;
     }
+    qemu_sem_post(&s->pause_sem);
+}
 
-    /* Cache should not be larger than guest ram size */
-    if (value > ram_bytes_total()) {
-        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
-                   "exceeds guest ram size ");
-        return;
-    }
+void qmp_migrate_set_cache_size(int64_t value, Error **errp)
+{
+    MigrationState *s = migrate_get_current();
+    int64_t new_size;
 
-    new_size = xbzrle_cache_resize(value);
+    new_size = xbzrle_cache_resize(value, errp);
     if (new_size < 0) {
-        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
-                   "is smaller than page size");
         return;
     }
 
@@ -1521,6 +1546,16 @@ bool migrate_use_multifd(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_X_MULTIFD];
 }
 
+bool migrate_pause_before_switchover(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[
+        MIGRATION_CAPABILITY_PAUSE_BEFORE_SWITCHOVER];
+}
+
 int migrate_multifd_channels(void)
 {
     MigrationState *s;
@@ -1799,8 +1834,11 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running)
     QEMUFile *fb;
     int64_t time_at_stop = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
     bool restart_block = false;
-    migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,
-                      MIGRATION_STATUS_POSTCOPY_ACTIVE);
+    int cur_state = MIGRATION_STATUS_ACTIVE;
+    if (!migrate_pause_before_switchover()) {
+        migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,
+                          MIGRATION_STATUS_POSTCOPY_ACTIVE);
+    }
 
     trace_postcopy_start();
     qemu_mutex_lock_iothread();
@@ -1814,6 +1852,12 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running)
         goto fail;
     }
 
+    ret = migration_maybe_pause(ms, &cur_state,
+                                MIGRATION_STATUS_POSTCOPY_ACTIVE);
+    if (ret < 0) {
+        goto fail;
+    }
+
     ret = bdrv_inactivate_all();
     if (ret < 0) {
         goto fail;
@@ -1952,6 +1996,41 @@ fail:
 }
 
 /**
+ * migration_maybe_pause: Pause if required to by
+ * migrate_pause_before_switchover called with the iothread locked
+ * Returns: 0 on success
+ */
+static int migration_maybe_pause(MigrationState *s,
+                                 int *current_active_state,
+                                 int new_state)
+{
+    if (!migrate_pause_before_switchover()) {
+        return 0;
+    }
+
+    /* Since leaving this state is not atomic with posting the semaphore
+     * it's possible that someone could have issued multiple migrate_continue
+     * and the semaphore is incorrectly positive at this point;
+     * the docs say it's undefined to reinit a semaphore that's already
+     * init'd, so use timedwait to eat up any existing posts.
+     */
+    while (qemu_sem_timedwait(&s->pause_sem, 1) == 0) {
+        /* This block intentionally left blank */
+    }
+
+    qemu_mutex_unlock_iothread();
+    migrate_set_state(&s->state, *current_active_state,
+                      MIGRATION_STATUS_PRE_SWITCHOVER);
+    qemu_sem_wait(&s->pause_sem);
+    migrate_set_state(&s->state, MIGRATION_STATUS_PRE_SWITCHOVER,
+                      new_state);
+    *current_active_state = new_state;
+    qemu_mutex_lock_iothread();
+
+    return s->state == new_state ? 0 : -EINVAL;
+}
+
+/**
  * migration_completion: Used by migration_thread when there's not much left.
  *   The caller 'breaks' the loop when this returns.
  *
@@ -1977,6 +2056,10 @@ static void migration_completion(MigrationState *s, int current_active_state,
             bool inactivate = !migrate_colo_enabled();
             ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
             if (ret >= 0) {
+                ret = migration_maybe_pause(s, &current_active_state,
+                                            MIGRATION_STATUS_DEVICE);
+            }
+            if (ret >= 0) {
                 qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);
                 ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false,
                                                          inactivate);
@@ -2355,8 +2438,10 @@ static void migration_instance_finalize(Object *obj)
     MigrationState *ms = MIGRATION_OBJ(obj);
     MigrationParameters *params = &ms->parameters;
 
+    qemu_mutex_destroy(&ms->error_mutex);
     g_free(params->tls_hostname);
     g_free(params->tls_creds);
+    qemu_sem_destroy(&ms->pause_sem);
 }
 
 static void migration_instance_init(Object *obj)
@@ -2367,6 +2452,8 @@ static void migration_instance_init(Object *obj)
     ms->state = MIGRATION_STATUS_NONE;
     ms->xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE;
     ms->mbps = -1;
+    qemu_sem_init(&ms->pause_sem, 0);
+    qemu_mutex_init(&ms->error_mutex);
 
     params->tls_hostname = g_strdup("");
     params->tls_creds = g_strdup("");