Merge tag 'migration-20240331-pull-request' of https://gitlab.com/pet…

…erx/qemu into staging

Migration pull for 9.0-rc2

- Avihai's two fixes on error paths

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* tag 'migration-20240331-pull-request' of https://gitlab.com/peterx/qemu:
  migration/postcopy: Ensure postcopy_start() sets errp if it fails
  migration: Set migration error in migration_completion()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

migration/migration.c

@@ -2510,6 +2510,8 @@ static int postcopy_start(MigrationState *ms, Error **errp)
         migration_wait_main_channel(ms);
         if (postcopy_preempt_establish_channel(ms)) {
             migrate_set_state(&ms->state, ms->state, MIGRATION_STATUS_FAILED);
+            error_setg(errp, "%s: Failed to establish preempt channel",
+                       __func__);
             return -1;
         }
     }
@@ -2525,17 +2527,22 @@ static int postcopy_start(MigrationState *ms, Error **errp)
 
     ret = migration_stop_vm(ms, RUN_STATE_FINISH_MIGRATE);
     if (ret < 0) {
+        error_setg_errno(errp, -ret, "%s: Failed to stop the VM", __func__);
         goto fail;
     }
 
     ret = migration_maybe_pause(ms, &cur_state,
                                 MIGRATION_STATUS_POSTCOPY_ACTIVE);
     if (ret < 0) {
+        error_setg_errno(errp, -ret, "%s: Failed in migration_maybe_pause()",
+                         __func__);
         goto fail;
     }
 
     ret = bdrv_inactivate_all();
     if (ret < 0) {
+        error_setg_errno(errp, -ret, "%s: Failed in bdrv_inactivate_all()",
+                         __func__);
         goto fail;
     }
     restart_block = true;
@@ -2612,6 +2619,7 @@ static int postcopy_start(MigrationState *ms, Error **errp)
 
     /* Now send that blob */
     if (qemu_savevm_send_packaged(ms->to_dst_file, bioc->data, bioc->usage)) {
+        error_setg(errp, "%s: Failed to send packaged data", __func__);
         goto fail_closefb;
     }
     qemu_fclose(fb);
@@ -2799,6 +2807,7 @@ static void migration_completion(MigrationState *s)
 {
     int ret = 0;
     int current_active_state = s->state;
+    Error *local_err = NULL;
 
     if (s->state == MIGRATION_STATUS_ACTIVE) {
         ret = migration_completion_precopy(s, &current_active_state);
@@ -2832,6 +2841,15 @@ static void migration_completion(MigrationState *s)
     return;
 
 fail:
+    if (qemu_file_get_error_obj(s->to_dst_file, &local_err)) {
+        migrate_set_error(s, local_err);
+        error_free(local_err);
+    } else if (ret) {
+        error_setg_errno(&local_err, -ret, "Error in migration completion");
+        migrate_set_error(s, local_err);
+        error_free(local_err);
+    }
+
     migration_completion_failed(s, current_active_state);
 }