migration/colo.c

   1 /*
   2  * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
   3  * (a.k.a. Fault Tolerance or Continuous Replication)
   4  *
   5  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
   6  * Copyright (c) 2016 FUJITSU LIMITED
   7  * Copyright (c) 2016 Intel Corporation
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or
  10  * later.  See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "sysemu/sysemu.h"
  15 #include "qapi/error.h"
  16 #include "qapi/qapi-commands-migration.h"
  17 #include "qemu-file-channel.h"
  18 #include "migration.h"
  19 #include "qemu-file.h"
  20 #include "savevm.h"
  21 #include "migration/colo.h"
  22 #include "block.h"
  23 #include "io/channel-buffer.h"
  24 #include "trace.h"
  25 #include "qemu/error-report.h"
  26 #include "qemu/main-loop.h"
  27 #include "qemu/rcu.h"
  28 #include "migration/failover.h"
  29 #include "migration/ram.h"
  30 #ifdef CONFIG_REPLICATION
  31 #include "block/replication.h"
  32 #endif
  33 #include "net/colo-compare.h"
  34 #include "net/colo.h"
  35 #include "block/block.h"
  36 #include "qapi/qapi-events-migration.h"
  37 #include "qapi/qmp/qerror.h"
  38 #include "sysemu/cpus.h"
  39 #include "sysemu/runstate.h"
  40 #include "net/filter.h"
  41
  42 static bool vmstate_loading;
  43 static Notifier packets_compare_notifier;
  44
  45 /* User need to know colo mode after COLO failover */
  46 static COLOMode last_colo_mode;
  47
  48 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
  49
  50 bool migration_in_colo_state(void)
  51 {
  52     MigrationState *s = migrate_get_current();
  53
  54     return (s->state == MIGRATION_STATUS_COLO);
  55 }
  56
  57 bool migration_incoming_in_colo_state(void)
  58 {
  59     MigrationIncomingState *mis = migration_incoming_get_current();
  60
  61     return mis && (mis->state == MIGRATION_STATUS_COLO);
  62 }
  63
  64 static bool colo_runstate_is_stopped(void)
  65 {
  66     return runstate_check(RUN_STATE_COLO) || !runstate_is_running();
  67 }
  68
  69 static void secondary_vm_do_failover(void)
  70 {
  71 /* COLO needs enable block-replication */
  72 #ifdef CONFIG_REPLICATION
  73     int old_state;
  74     MigrationIncomingState *mis = migration_incoming_get_current();
  75     Error *local_err = NULL;
  76
  77     /* Can not do failover during the process of VM's loading VMstate, Or
  78      * it will break the secondary VM.
  79      */
  80     if (vmstate_loading) {
  81         old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
  82                         FAILOVER_STATUS_RELAUNCH);
  83         if (old_state != FAILOVER_STATUS_ACTIVE) {
  84             error_report("Unknown error while do failover for secondary VM,"
  85                          "old_state: %s", FailoverStatus_str(old_state));
  86         }
  87         return;
  88     }
  89
  90     migrate_set_state(&mis->state, MIGRATION_STATUS_COLO,
  91                       MIGRATION_STATUS_COMPLETED);
  92
  93     replication_stop_all(true, &local_err);
  94     if (local_err) {
  95         error_report_err(local_err);
  96         local_err = NULL;
  97     }
  98
  99     /* Notify all filters of all NIC to do checkpoint */
 100     colo_notify_filters_event(COLO_EVENT_FAILOVER, &local_err);
 101     if (local_err) {
 102         error_report_err(local_err);
 103     }
 104
 105     if (!autostart) {
 106         error_report("\"-S\" qemu option will be ignored in secondary side");
 107         /* recover runstate to normal migration finish state */
 108         autostart = true;
 109     }
 110     /*
 111      * Make sure COLO incoming thread not block in recv or send,
 112      * If mis->from_src_file and mis->to_src_file use the same fd,
 113      * The second shutdown() will return -1, we ignore this value,
 114      * It is harmless.
 115      */
 116     if (mis->from_src_file) {
 117         qemu_file_shutdown(mis->from_src_file);
 118     }
 119     if (mis->to_src_file) {
 120         qemu_file_shutdown(mis->to_src_file);
 121     }
 122
 123     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
 124                                    FAILOVER_STATUS_COMPLETED);
 125     if (old_state != FAILOVER_STATUS_ACTIVE) {
 126         error_report("Incorrect state (%s) while doing failover for "
 127                      "secondary VM", FailoverStatus_str(old_state));
 128         return;
 129     }
 130     /* Notify COLO incoming thread that failover work is finished */
 131     qemu_sem_post(&mis->colo_incoming_sem);
 132
 133     /* For Secondary VM, jump to incoming co */
 134     if (mis->migration_incoming_co) {
 135         qemu_coroutine_enter(mis->migration_incoming_co);
 136     }
 137 #else
 138     abort();
 139 #endif
 140 }
 141
 142 static void primary_vm_do_failover(void)
 143 {
 144 #ifdef CONFIG_REPLICATION
 145     MigrationState *s = migrate_get_current();
 146     int old_state;
 147     Error *local_err = NULL;
 148
 149     migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
 150                       MIGRATION_STATUS_COMPLETED);
 151     /*
 152      * kick COLO thread which might wait at
 153      * qemu_sem_wait(&s->colo_checkpoint_sem).
 154      */
 155     colo_checkpoint_notify(s);
 156
 157     /*
 158      * Wake up COLO thread which may blocked in recv() or send(),
 159      * The s->rp_state.from_dst_file and s->to_dst_file may use the
 160      * same fd, but we still shutdown the fd for twice, it is harmless.
 161      */
 162     if (s->to_dst_file) {
 163         qemu_file_shutdown(s->to_dst_file);
 164     }
 165     if (s->rp_state.from_dst_file) {
 166         qemu_file_shutdown(s->rp_state.from_dst_file);
 167     }
 168
 169     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
 170                                    FAILOVER_STATUS_COMPLETED);
 171     if (old_state != FAILOVER_STATUS_ACTIVE) {
 172         error_report("Incorrect state (%s) while doing failover for Primary VM",
 173                      FailoverStatus_str(old_state));
 174         return;
 175     }
 176
 177     replication_stop_all(true, &local_err);
 178     if (local_err) {
 179         error_report_err(local_err);
 180         local_err = NULL;
 181     }
 182
 183     /* Notify COLO thread that failover work is finished */
 184     qemu_sem_post(&s->colo_exit_sem);
 185 #else
 186     abort();
 187 #endif
 188 }
 189
 190 COLOMode get_colo_mode(void)
 191 {
 192     if (migration_in_colo_state()) {
 193         return COLO_MODE_PRIMARY;
 194     } else if (migration_incoming_in_colo_state()) {
 195         return COLO_MODE_SECONDARY;
 196     } else {
 197         return COLO_MODE_NONE;
 198     }
 199 }
 200
 201 void colo_do_failover(void)
 202 {
 203     /* Make sure VM stopped while failover happened. */
 204     if (!colo_runstate_is_stopped()) {
 205         vm_stop_force_state(RUN_STATE_COLO);
 206     }
 207
 208     switch (last_colo_mode = get_colo_mode()) {
 209     case COLO_MODE_PRIMARY:
 210         primary_vm_do_failover();
 211         break;
 212     case COLO_MODE_SECONDARY:
 213         secondary_vm_do_failover();
 214         break;
 215     default:
 216         error_report("colo_do_failover failed because the colo mode"
 217                      " could not be obtained");
 218     }
 219 }
 220
 221 #ifdef CONFIG_REPLICATION
 222 void qmp_xen_set_replication(bool enable, bool primary,
 223                              bool has_failover, bool failover,
 224                              Error **errp)
 225 {
 226     ReplicationMode mode = primary ?
 227                            REPLICATION_MODE_PRIMARY :
 228                            REPLICATION_MODE_SECONDARY;
 229
 230     if (has_failover && enable) {
 231         error_setg(errp, "Parameter 'failover' is only for"
 232                    " stopping replication");
 233         return;
 234     }
 235
 236     if (enable) {
 237         replication_start_all(mode, errp);
 238     } else {
 239         if (!has_failover) {
 240             failover = NULL;
 241         }
 242         replication_stop_all(failover, failover ? NULL : errp);
 243     }
 244 }
 245
 246 ReplicationStatus *qmp_query_xen_replication_status(Error **errp)
 247 {
 248     Error *err = NULL;
 249     ReplicationStatus *s = g_new0(ReplicationStatus, 1);
 250
 251     replication_get_error_all(&err);
 252     if (err) {
 253         s->error = true;
 254         s->has_desc = true;
 255         s->desc = g_strdup(error_get_pretty(err));
 256     } else {
 257         s->error = false;
 258     }
 259
 260     error_free(err);
 261     return s;
 262 }
 263
 264 void qmp_xen_colo_do_checkpoint(Error **errp)
 265 {
 266     Error *err = NULL;
 267
 268     replication_do_checkpoint_all(&err);
 269     if (err) {
 270         error_propagate(errp, err);
 271         return;
 272     }
 273     /* Notify all filters of all NIC to do checkpoint */
 274     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, errp);
 275 }
 276 #endif
 277
 278 COLOStatus *qmp_query_colo_status(Error **errp)
 279 {
 280     COLOStatus *s = g_new0(COLOStatus, 1);
 281
 282     s->mode = get_colo_mode();
 283     s->last_mode = last_colo_mode;
 284
 285     switch (failover_get_state()) {
 286     case FAILOVER_STATUS_NONE:
 287         s->reason = COLO_EXIT_REASON_NONE;
 288         break;
 289     case FAILOVER_STATUS_COMPLETED:
 290         s->reason = COLO_EXIT_REASON_REQUEST;
 291         break;
 292     default:
 293         if (migration_in_colo_state()) {
 294             s->reason = COLO_EXIT_REASON_PROCESSING;
 295         } else {
 296             s->reason = COLO_EXIT_REASON_ERROR;
 297         }
 298     }
 299
 300     return s;
 301 }
 302
 303 static void colo_send_message(QEMUFile *f, COLOMessage msg,
 304                               Error **errp)
 305 {
 306     int ret;
 307
 308     if (msg >= COLO_MESSAGE__MAX) {
 309         error_setg(errp, "%s: Invalid message", __func__);
 310         return;
 311     }
 312     qemu_put_be32(f, msg);
 313     qemu_fflush(f);
 314
 315     ret = qemu_file_get_error(f);
 316     if (ret < 0) {
 317         error_setg_errno(errp, -ret, "Can't send COLO message");
 318     }
 319     trace_colo_send_message(COLOMessage_str(msg));
 320 }
 321
 322 static void colo_send_message_value(QEMUFile *f, COLOMessage msg,
 323                                     uint64_t value, Error **errp)
 324 {
 325     Error *local_err = NULL;
 326     int ret;
 327
 328     colo_send_message(f, msg, &local_err);
 329     if (local_err) {
 330         error_propagate(errp, local_err);
 331         return;
 332     }
 333     qemu_put_be64(f, value);
 334     qemu_fflush(f);
 335
 336     ret = qemu_file_get_error(f);
 337     if (ret < 0) {
 338         error_setg_errno(errp, -ret, "Failed to send value for message:%s",
 339                          COLOMessage_str(msg));
 340     }
 341 }
 342
 343 static COLOMessage colo_receive_message(QEMUFile *f, Error **errp)
 344 {
 345     COLOMessage msg;
 346     int ret;
 347
 348     msg = qemu_get_be32(f);
 349     ret = qemu_file_get_error(f);
 350     if (ret < 0) {
 351         error_setg_errno(errp, -ret, "Can't receive COLO message");
 352         return msg;
 353     }
 354     if (msg >= COLO_MESSAGE__MAX) {
 355         error_setg(errp, "%s: Invalid message", __func__);
 356         return msg;
 357     }
 358     trace_colo_receive_message(COLOMessage_str(msg));
 359     return msg;
 360 }
 361
 362 static void colo_receive_check_message(QEMUFile *f, COLOMessage expect_msg,
 363                                        Error **errp)
 364 {
 365     COLOMessage msg;
 366     Error *local_err = NULL;
 367
 368     msg = colo_receive_message(f, &local_err);
 369     if (local_err) {
 370         error_propagate(errp, local_err);
 371         return;
 372     }
 373     if (msg != expect_msg) {
 374         error_setg(errp, "Unexpected COLO message %d, expected %d",
 375                           msg, expect_msg);
 376     }
 377 }
 378
 379 static uint64_t colo_receive_message_value(QEMUFile *f, uint32_t expect_msg,
 380                                            Error **errp)
 381 {
 382     Error *local_err = NULL;
 383     uint64_t value;
 384     int ret;
 385
 386     colo_receive_check_message(f, expect_msg, &local_err);
 387     if (local_err) {
 388         error_propagate(errp, local_err);
 389         return 0;
 390     }
 391
 392     value = qemu_get_be64(f);
 393     ret = qemu_file_get_error(f);
 394     if (ret < 0) {
 395         error_setg_errno(errp, -ret, "Failed to get value for COLO message: %s",
 396                          COLOMessage_str(expect_msg));
 397     }
 398     return value;
 399 }
 400
 401 static int colo_do_checkpoint_transaction(MigrationState *s,
 402                                           QIOChannelBuffer *bioc,
 403                                           QEMUFile *fb)
 404 {
 405     Error *local_err = NULL;
 406     int ret = -1;
 407
 408     colo_send_message(s->to_dst_file, COLO_MESSAGE_CHECKPOINT_REQUEST,
 409                       &local_err);
 410     if (local_err) {
 411         goto out;
 412     }
 413
 414     colo_receive_check_message(s->rp_state.from_dst_file,
 415                     COLO_MESSAGE_CHECKPOINT_REPLY, &local_err);
 416     if (local_err) {
 417         goto out;
 418     }
 419     /* Reset channel-buffer directly */
 420     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 421     bioc->usage = 0;
 422
 423     qemu_mutex_lock_iothread();
 424     if (failover_get_state() != FAILOVER_STATUS_NONE) {
 425         qemu_mutex_unlock_iothread();
 426         goto out;
 427     }
 428     vm_stop_force_state(RUN_STATE_COLO);
 429     qemu_mutex_unlock_iothread();
 430     trace_colo_vm_state_change("run", "stop");
 431     /*
 432      * Failover request bh could be called after vm_stop_force_state(),
 433      * So we need check failover_request_is_active() again.
 434      */
 435     if (failover_get_state() != FAILOVER_STATUS_NONE) {
 436         goto out;
 437     }
 438     qemu_mutex_lock_iothread();
 439
 440 #ifdef CONFIG_REPLICATION
 441     replication_do_checkpoint_all(&local_err);
 442     if (local_err) {
 443         qemu_mutex_unlock_iothread();
 444         goto out;
 445     }
 446 #else
 447         abort();
 448 #endif
 449
 450     colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
 451     if (local_err) {
 452         qemu_mutex_unlock_iothread();
 453         goto out;
 454     }
 455     /* Note: device state is saved into buffer */
 456     ret = qemu_save_device_state(fb);
 457
 458     qemu_mutex_unlock_iothread();
 459     if (ret < 0) {
 460         goto out;
 461     }
 462
 463     if (migrate_auto_converge()) {
 464         mig_throttle_counter_reset();
 465     }
 466     /*
 467      * Only save VM's live state, which not including device state.
 468      * TODO: We may need a timeout mechanism to prevent COLO process
 469      * to be blocked here.
 470      */
 471     qemu_savevm_live_state(s->to_dst_file);
 472
 473     qemu_fflush(fb);
 474
 475     /*
 476      * We need the size of the VMstate data in Secondary side,
 477      * With which we can decide how much data should be read.
 478      */
 479     colo_send_message_value(s->to_dst_file, COLO_MESSAGE_VMSTATE_SIZE,
 480                             bioc->usage, &local_err);
 481     if (local_err) {
 482         goto out;
 483     }
 484
 485     qemu_put_buffer(s->to_dst_file, bioc->data, bioc->usage);
 486     qemu_fflush(s->to_dst_file);
 487     ret = qemu_file_get_error(s->to_dst_file);
 488     if (ret < 0) {
 489         goto out;
 490     }
 491
 492     colo_receive_check_message(s->rp_state.from_dst_file,
 493                        COLO_MESSAGE_VMSTATE_RECEIVED, &local_err);
 494     if (local_err) {
 495         goto out;
 496     }
 497
 498     qemu_event_reset(&s->colo_checkpoint_event);
 499     colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT, &local_err);
 500     if (local_err) {
 501         goto out;
 502     }
 503
 504     colo_receive_check_message(s->rp_state.from_dst_file,
 505                        COLO_MESSAGE_VMSTATE_LOADED, &local_err);
 506     if (local_err) {
 507         goto out;
 508     }
 509
 510     ret = 0;
 511
 512     qemu_mutex_lock_iothread();
 513     vm_start();
 514     qemu_mutex_unlock_iothread();
 515     trace_colo_vm_state_change("stop", "run");
 516
 517 out:
 518     if (local_err) {
 519         error_report_err(local_err);
 520     }
 521     return ret;
 522 }
 523
 524 static void colo_compare_notify_checkpoint(Notifier *notifier, void *data)
 525 {
 526     colo_checkpoint_notify(data);
 527 }
 528
 529 static void colo_process_checkpoint(MigrationState *s)
 530 {
 531     QIOChannelBuffer *bioc;
 532     QEMUFile *fb = NULL;
 533     Error *local_err = NULL;
 534     int ret;
 535
 536     if (get_colo_mode() != COLO_MODE_PRIMARY) {
 537         error_report("COLO mode must be COLO_MODE_PRIMARY");
 538         return;
 539     }
 540
 541     failover_init_state();
 542
 543     s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
 544     if (!s->rp_state.from_dst_file) {
 545         error_report("Open QEMUFile from_dst_file failed");
 546         goto out;
 547     }
 548
 549     packets_compare_notifier.notify = colo_compare_notify_checkpoint;
 550     colo_compare_register_notifier(&packets_compare_notifier);
 551
 552     /*
 553      * Wait for Secondary finish loading VM states and enter COLO
 554      * restore.
 555      */
 556     colo_receive_check_message(s->rp_state.from_dst_file,
 557                        COLO_MESSAGE_CHECKPOINT_READY, &local_err);
 558     if (local_err) {
 559         goto out;
 560     }
 561     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 562     fb = qemu_fopen_channel_output(QIO_CHANNEL(bioc));
 563     object_unref(OBJECT(bioc));
 564
 565     qemu_mutex_lock_iothread();
 566 #ifdef CONFIG_REPLICATION
 567     replication_start_all(REPLICATION_MODE_PRIMARY, &local_err);
 568     if (local_err) {
 569         qemu_mutex_unlock_iothread();
 570         goto out;
 571     }
 572 #else
 573         abort();
 574 #endif
 575
 576     vm_start();
 577     qemu_mutex_unlock_iothread();
 578     trace_colo_vm_state_change("stop", "run");
 579
 580     timer_mod(s->colo_delay_timer, qemu_clock_get_ms(QEMU_CLOCK_HOST) +
 581               s->parameters.x_checkpoint_delay);
 582
 583     while (s->state == MIGRATION_STATUS_COLO) {
 584         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 585             error_report("failover request");
 586             goto out;
 587         }
 588
 589         qemu_event_wait(&s->colo_checkpoint_event);
 590
 591         if (s->state != MIGRATION_STATUS_COLO) {
 592             goto out;
 593         }
 594         ret = colo_do_checkpoint_transaction(s, bioc, fb);
 595         if (ret < 0) {
 596             goto out;
 597         }
 598     }
 599
 600 out:
 601     /* Throw the unreported error message after exited from loop */
 602     if (local_err) {
 603         error_report_err(local_err);
 604     }
 605
 606     if (fb) {
 607         qemu_fclose(fb);
 608     }
 609
 610     /*
 611      * There are only two reasons we can get here, some error happened
 612      * or the user triggered failover.
 613      */
 614     switch (failover_get_state()) {
 615     case FAILOVER_STATUS_COMPLETED:
 616         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
 617                                   COLO_EXIT_REASON_REQUEST);
 618         break;
 619     default:
 620         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
 621                                   COLO_EXIT_REASON_ERROR);
 622     }
 623
 624     /* Hope this not to be too long to wait here */
 625     qemu_sem_wait(&s->colo_exit_sem);
 626     qemu_sem_destroy(&s->colo_exit_sem);
 627
 628     /*
 629      * It is safe to unregister notifier after failover finished.
 630      * Besides, colo_delay_timer and colo_checkpoint_sem can't be
 631      * released before unregister notifier, or there will be use-after-free
 632      * error.
 633      */
 634     colo_compare_unregister_notifier(&packets_compare_notifier);
 635     timer_free(s->colo_delay_timer);
 636     qemu_event_destroy(&s->colo_checkpoint_event);
 637
 638     /*
 639      * Must be called after failover BH is completed,
 640      * Or the failover BH may shutdown the wrong fd that
 641      * re-used by other threads after we release here.
 642      */
 643     if (s->rp_state.from_dst_file) {
 644         qemu_fclose(s->rp_state.from_dst_file);
 645         s->rp_state.from_dst_file = NULL;
 646     }
 647 }
 648
 649 void colo_checkpoint_notify(void *opaque)
 650 {
 651     MigrationState *s = opaque;
 652     int64_t next_notify_time;
 653
 654     qemu_event_set(&s->colo_checkpoint_event);
 655     s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 656     next_notify_time = s->colo_checkpoint_time +
 657                     s->parameters.x_checkpoint_delay;
 658     timer_mod(s->colo_delay_timer, next_notify_time);
 659 }
 660
 661 void migrate_start_colo_process(MigrationState *s)
 662 {
 663     qemu_mutex_unlock_iothread();
 664     qemu_event_init(&s->colo_checkpoint_event, false);
 665     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
 666                                 colo_checkpoint_notify, s);
 667
 668     qemu_sem_init(&s->colo_exit_sem, 0);
 669     colo_process_checkpoint(s);
 670     qemu_mutex_lock_iothread();
 671 }
 672
 673 static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
 674                       QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
 675 {
 676     uint64_t total_size;
 677     uint64_t value;
 678     Error *local_err = NULL;
 679     int ret;
 680
 681     qemu_mutex_lock_iothread();
 682     vm_stop_force_state(RUN_STATE_COLO);
 683     qemu_mutex_unlock_iothread();
 684     trace_colo_vm_state_change("run", "stop");
 685
 686     /* FIXME: This is unnecessary for periodic checkpoint mode */
 687     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
 688                  &local_err);
 689     if (local_err) {
 690         error_propagate(errp, local_err);
 691         return;
 692     }
 693
 694     colo_receive_check_message(mis->from_src_file,
 695                        COLO_MESSAGE_VMSTATE_SEND, &local_err);
 696     if (local_err) {
 697         error_propagate(errp, local_err);
 698         return;
 699     }
 700
 701     qemu_mutex_lock_iothread();
 702     cpu_synchronize_all_states();
 703     ret = qemu_loadvm_state_main(mis->from_src_file, mis);
 704     qemu_mutex_unlock_iothread();
 705
 706     if (ret < 0) {
 707         error_setg(errp, "Load VM's live state (ram) error");
 708         return;
 709     }
 710
 711     value = colo_receive_message_value(mis->from_src_file,
 712                              COLO_MESSAGE_VMSTATE_SIZE, &local_err);
 713     if (local_err) {
 714         error_propagate(errp, local_err);
 715         return;
 716     }
 717
 718     /*
 719      * Read VM device state data into channel buffer,
 720      * It's better to re-use the memory allocated.
 721      * Here we need to handle the channel buffer directly.
 722      */
 723     if (value > bioc->capacity) {
 724         bioc->capacity = value;
 725         bioc->data = g_realloc(bioc->data, bioc->capacity);
 726     }
 727     total_size = qemu_get_buffer(mis->from_src_file, bioc->data, value);
 728     if (total_size != value) {
 729         error_setg(errp, "Got %" PRIu64 " VMState data, less than expected"
 730                     " %" PRIu64, total_size, value);
 731         return;
 732     }
 733     bioc->usage = total_size;
 734     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 735
 736     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
 737                  &local_err);
 738     if (local_err) {
 739         error_propagate(errp, local_err);
 740         return;
 741     }
 742
 743     qemu_mutex_lock_iothread();
 744     vmstate_loading = true;
 745     colo_flush_ram_cache();
 746     ret = qemu_load_device_state(fb);
 747     if (ret < 0) {
 748         error_setg(errp, "COLO: load device state failed");
 749         vmstate_loading = false;
 750         qemu_mutex_unlock_iothread();
 751         return;
 752     }
 753
 754 #ifdef CONFIG_REPLICATION
 755     replication_get_error_all(&local_err);
 756     if (local_err) {
 757         error_propagate(errp, local_err);
 758         vmstate_loading = false;
 759         qemu_mutex_unlock_iothread();
 760         return;
 761     }
 762
 763     /* discard colo disk buffer */
 764     replication_do_checkpoint_all(&local_err);
 765     if (local_err) {
 766         error_propagate(errp, local_err);
 767         vmstate_loading = false;
 768         qemu_mutex_unlock_iothread();
 769         return;
 770     }
 771 #else
 772     abort();
 773 #endif
 774     /* Notify all filters of all NIC to do checkpoint */
 775     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, &local_err);
 776
 777     if (local_err) {
 778         error_propagate(errp, local_err);
 779         vmstate_loading = false;
 780         qemu_mutex_unlock_iothread();
 781         return;
 782     }
 783
 784     vmstate_loading = false;
 785     vm_start();
 786     qemu_mutex_unlock_iothread();
 787     trace_colo_vm_state_change("stop", "run");
 788
 789     if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 790         return;
 791     }
 792
 793     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
 794                  &local_err);
 795     error_propagate(errp, local_err);
 796 }
 797
 798 static void colo_wait_handle_message(MigrationIncomingState *mis,
 799                 QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
 800 {
 801     COLOMessage msg;
 802     Error *local_err = NULL;
 803
 804     msg = colo_receive_message(mis->from_src_file, &local_err);
 805     if (local_err) {
 806         error_propagate(errp, local_err);
 807         return;
 808     }
 809
 810     switch (msg) {
 811     case COLO_MESSAGE_CHECKPOINT_REQUEST:
 812         colo_incoming_process_checkpoint(mis, fb, bioc, errp);
 813         break;
 814     default:
 815         error_setg(errp, "Got unknown COLO message: %d", msg);
 816         break;
 817     }
 818 }
 819
 820 void colo_shutdown(void)
 821 {
 822     MigrationIncomingState *mis = NULL;
 823     MigrationState *s = NULL;
 824
 825     switch (get_colo_mode()) {
 826     case COLO_MODE_PRIMARY:
 827         s = migrate_get_current();
 828         qemu_event_set(&s->colo_checkpoint_event);
 829         qemu_sem_post(&s->colo_exit_sem);
 830         break;
 831     case COLO_MODE_SECONDARY:
 832         mis = migration_incoming_get_current();
 833         qemu_sem_post(&mis->colo_incoming_sem);
 834         break;
 835     default:
 836         break;
 837     }
 838 }
 839
 840 void *colo_process_incoming_thread(void *opaque)
 841 {
 842     MigrationIncomingState *mis = opaque;
 843     QEMUFile *fb = NULL;
 844     QIOChannelBuffer *bioc = NULL; /* Cache incoming device state */
 845     Error *local_err = NULL;
 846
 847     rcu_register_thread();
 848     qemu_sem_init(&mis->colo_incoming_sem, 0);
 849
 850     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
 851                       MIGRATION_STATUS_COLO);
 852
 853     if (get_colo_mode() != COLO_MODE_SECONDARY) {
 854         error_report("COLO mode must be COLO_MODE_SECONDARY");
 855         return NULL;
 856     }
 857
 858     failover_init_state();
 859
 860     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
 861     if (!mis->to_src_file) {
 862         error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
 863         goto out;
 864     }
 865     /*
 866      * Note: the communication between Primary side and Secondary side
 867      * should be sequential, we set the fd to unblocked in migration incoming
 868      * coroutine, and here we are in the COLO incoming thread, so it is ok to
 869      * set the fd back to blocked.
 870      */
 871     qemu_file_set_blocking(mis->from_src_file, true);
 872
 873     colo_incoming_start_dirty_log();
 874
 875     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 876     fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
 877     object_unref(OBJECT(bioc));
 878
 879     qemu_mutex_lock_iothread();
 880 #ifdef CONFIG_REPLICATION
 881     replication_start_all(REPLICATION_MODE_SECONDARY, &local_err);
 882     if (local_err) {
 883         qemu_mutex_unlock_iothread();
 884         goto out;
 885     }
 886 #else
 887         abort();
 888 #endif
 889     vm_start();
 890     qemu_mutex_unlock_iothread();
 891     trace_colo_vm_state_change("stop", "run");
 892
 893     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
 894                       &local_err);
 895     if (local_err) {
 896         goto out;
 897     }
 898
 899     while (mis->state == MIGRATION_STATUS_COLO) {
 900         colo_wait_handle_message(mis, fb, bioc, &local_err);
 901         if (local_err) {
 902             error_report_err(local_err);
 903             break;
 904         }
 905
 906         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 907             failover_set_state(FAILOVER_STATUS_RELAUNCH,
 908                             FAILOVER_STATUS_NONE);
 909             failover_request_active(NULL);
 910             break;
 911         }
 912
 913         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 914             error_report("failover request");
 915             break;
 916         }
 917     }
 918
 919 out:
 920     /*
 921      * There are only two reasons we can get here, some error happened
 922      * or the user triggered failover.
 923      */
 924     switch (failover_get_state()) {
 925     case FAILOVER_STATUS_COMPLETED:
 926         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
 927                                   COLO_EXIT_REASON_REQUEST);
 928         break;
 929     default:
 930         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
 931                                   COLO_EXIT_REASON_ERROR);
 932     }
 933
 934     if (fb) {
 935         qemu_fclose(fb);
 936     }
 937
 938     /* Hope this not to be too long to loop here */
 939     qemu_sem_wait(&mis->colo_incoming_sem);
 940     qemu_sem_destroy(&mis->colo_incoming_sem);
 941
 942     rcu_unregister_thread();
 943     return NULL;
 944 }