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(migrate_get_current());
 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 (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      * Only save VM's live state, which not including device state.
 464      * TODO: We may need a timeout mechanism to prevent COLO process
 465      * to be blocked here.
 466      */
 467     qemu_savevm_live_state(s->to_dst_file);
 468
 469     qemu_fflush(fb);
 470
 471     /*
 472      * We need the size of the VMstate data in Secondary side,
 473      * With which we can decide how much data should be read.
 474      */
 475     colo_send_message_value(s->to_dst_file, COLO_MESSAGE_VMSTATE_SIZE,
 476                             bioc->usage, &local_err);
 477     if (local_err) {
 478         goto out;
 479     }
 480
 481     qemu_put_buffer(s->to_dst_file, bioc->data, bioc->usage);
 482     qemu_fflush(s->to_dst_file);
 483     ret = qemu_file_get_error(s->to_dst_file);
 484     if (ret < 0) {
 485         goto out;
 486     }
 487
 488     colo_receive_check_message(s->rp_state.from_dst_file,
 489                        COLO_MESSAGE_VMSTATE_RECEIVED, &local_err);
 490     if (local_err) {
 491         goto out;
 492     }
 493
 494     qemu_event_reset(&s->colo_checkpoint_event);
 495     colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT, &local_err);
 496     if (local_err) {
 497         goto out;
 498     }
 499
 500     colo_receive_check_message(s->rp_state.from_dst_file,
 501                        COLO_MESSAGE_VMSTATE_LOADED, &local_err);
 502     if (local_err) {
 503         goto out;
 504     }
 505
 506     ret = 0;
 507
 508     qemu_mutex_lock_iothread();
 509     vm_start();
 510     qemu_mutex_unlock_iothread();
 511     trace_colo_vm_state_change("stop", "run");
 512
 513 out:
 514     if (local_err) {
 515         error_report_err(local_err);
 516     }
 517     return ret;
 518 }
 519
 520 static void colo_compare_notify_checkpoint(Notifier *notifier, void *data)
 521 {
 522     colo_checkpoint_notify(data);
 523 }
 524
 525 static void colo_process_checkpoint(MigrationState *s)
 526 {
 527     QIOChannelBuffer *bioc;
 528     QEMUFile *fb = NULL;
 529     int64_t current_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 530     Error *local_err = NULL;
 531     int ret;
 532
 533     last_colo_mode = get_colo_mode();
 534     if (last_colo_mode != COLO_MODE_PRIMARY) {
 535         error_report("COLO mode must be COLO_MODE_PRIMARY");
 536         return;
 537     }
 538
 539     failover_init_state();
 540
 541     s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
 542     if (!s->rp_state.from_dst_file) {
 543         error_report("Open QEMUFile from_dst_file failed");
 544         goto out;
 545     }
 546
 547     packets_compare_notifier.notify = colo_compare_notify_checkpoint;
 548     colo_compare_register_notifier(&packets_compare_notifier);
 549
 550     /*
 551      * Wait for Secondary finish loading VM states and enter COLO
 552      * restore.
 553      */
 554     colo_receive_check_message(s->rp_state.from_dst_file,
 555                        COLO_MESSAGE_CHECKPOINT_READY, &local_err);
 556     if (local_err) {
 557         goto out;
 558     }
 559     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 560     fb = qemu_fopen_channel_output(QIO_CHANNEL(bioc));
 561     object_unref(OBJECT(bioc));
 562
 563     qemu_mutex_lock_iothread();
 564 #ifdef CONFIG_REPLICATION
 565     replication_start_all(REPLICATION_MODE_PRIMARY, &local_err);
 566     if (local_err) {
 567         qemu_mutex_unlock_iothread();
 568         goto out;
 569     }
 570 #else
 571         abort();
 572 #endif
 573
 574     vm_start();
 575     qemu_mutex_unlock_iothread();
 576     trace_colo_vm_state_change("stop", "run");
 577
 578     timer_mod(s->colo_delay_timer,
 579             current_time + s->parameters.x_checkpoint_delay);
 580
 581     while (s->state == MIGRATION_STATUS_COLO) {
 582         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 583             error_report("failover request");
 584             goto out;
 585         }
 586
 587         qemu_event_wait(&s->colo_checkpoint_event);
 588
 589         if (s->state != MIGRATION_STATUS_COLO) {
 590             goto out;
 591         }
 592         ret = colo_do_checkpoint_transaction(s, bioc, fb);
 593         if (ret < 0) {
 594             goto out;
 595         }
 596     }
 597
 598 out:
 599     /* Throw the unreported error message after exited from loop */
 600     if (local_err) {
 601         error_report_err(local_err);
 602     }
 603
 604     if (fb) {
 605         qemu_fclose(fb);
 606     }
 607
 608     /*
 609      * There are only two reasons we can get here, some error happened
 610      * or the user triggered failover.
 611      */
 612     switch (failover_get_state()) {
 613     case FAILOVER_STATUS_COMPLETED:
 614         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
 615                                   COLO_EXIT_REASON_REQUEST);
 616         break;
 617     default:
 618         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
 619                                   COLO_EXIT_REASON_ERROR);
 620     }
 621
 622     /* Hope this not to be too long to wait here */
 623     qemu_sem_wait(&s->colo_exit_sem);
 624     qemu_sem_destroy(&s->colo_exit_sem);
 625
 626     /*
 627      * It is safe to unregister notifier after failover finished.
 628      * Besides, colo_delay_timer and colo_checkpoint_sem can't be
 629      * released before unregister notifier, or there will be use-after-free
 630      * error.
 631      */
 632     colo_compare_unregister_notifier(&packets_compare_notifier);
 633     timer_free(s->colo_delay_timer);
 634     qemu_event_destroy(&s->colo_checkpoint_event);
 635
 636     /*
 637      * Must be called after failover BH is completed,
 638      * Or the failover BH may shutdown the wrong fd that
 639      * re-used by other threads after we release here.
 640      */
 641     if (s->rp_state.from_dst_file) {
 642         qemu_fclose(s->rp_state.from_dst_file);
 643     }
 644 }
 645
 646 void colo_checkpoint_notify(void *opaque)
 647 {
 648     MigrationState *s = opaque;
 649     int64_t next_notify_time;
 650
 651     qemu_event_set(&s->colo_checkpoint_event);
 652     s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 653     next_notify_time = s->colo_checkpoint_time +
 654                     s->parameters.x_checkpoint_delay;
 655     timer_mod(s->colo_delay_timer, next_notify_time);
 656 }
 657
 658 void migrate_start_colo_process(MigrationState *s)
 659 {
 660     qemu_mutex_unlock_iothread();
 661     qemu_event_init(&s->colo_checkpoint_event, false);
 662     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
 663                                 colo_checkpoint_notify, s);
 664
 665     qemu_sem_init(&s->colo_exit_sem, 0);
 666     migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
 667                       MIGRATION_STATUS_COLO);
 668     colo_process_checkpoint(s);
 669     qemu_mutex_lock_iothread();
 670 }
 671
 672 static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
 673                       QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
 674 {
 675     uint64_t total_size;
 676     uint64_t value;
 677     Error *local_err = NULL;
 678     int ret;
 679
 680     qemu_mutex_lock_iothread();
 681     vm_stop_force_state(RUN_STATE_COLO);
 682     trace_colo_vm_state_change("run", "stop");
 683     qemu_mutex_unlock_iothread();
 684
 685     /* FIXME: This is unnecessary for periodic checkpoint mode */
 686     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
 687                  &local_err);
 688     if (local_err) {
 689         error_propagate(errp, local_err);
 690         return;
 691     }
 692
 693     colo_receive_check_message(mis->from_src_file,
 694                        COLO_MESSAGE_VMSTATE_SEND, &local_err);
 695     if (local_err) {
 696         error_propagate(errp, local_err);
 697         return;
 698     }
 699
 700     qemu_mutex_lock_iothread();
 701     cpu_synchronize_all_states();
 702     ret = qemu_loadvm_state_main(mis->from_src_file, mis);
 703     qemu_mutex_unlock_iothread();
 704
 705     if (ret < 0) {
 706         error_setg(errp, "Load VM's live state (ram) error");
 707         return;
 708     }
 709
 710     value = colo_receive_message_value(mis->from_src_file,
 711                              COLO_MESSAGE_VMSTATE_SIZE, &local_err);
 712     if (local_err) {
 713         error_propagate(errp, local_err);
 714         return;
 715     }
 716
 717     /*
 718      * Read VM device state data into channel buffer,
 719      * It's better to re-use the memory allocated.
 720      * Here we need to handle the channel buffer directly.
 721      */
 722     if (value > bioc->capacity) {
 723         bioc->capacity = value;
 724         bioc->data = g_realloc(bioc->data, bioc->capacity);
 725     }
 726     total_size = qemu_get_buffer(mis->from_src_file, bioc->data, value);
 727     if (total_size != value) {
 728         error_setg(errp, "Got %" PRIu64 " VMState data, less than expected"
 729                     " %" PRIu64, total_size, value);
 730         return;
 731     }
 732     bioc->usage = total_size;
 733     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 734
 735     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
 736                  &local_err);
 737     if (local_err) {
 738         error_propagate(errp, local_err);
 739         return;
 740     }
 741
 742     qemu_mutex_lock_iothread();
 743     vmstate_loading = true;
 744     colo_flush_ram_cache();
 745     ret = qemu_load_device_state(fb);
 746     if (ret < 0) {
 747         error_setg(errp, "COLO: load device state failed");
 748         vmstate_loading = false;
 749         qemu_mutex_unlock_iothread();
 750         return;
 751     }
 752
 753 #ifdef CONFIG_REPLICATION
 754     replication_get_error_all(&local_err);
 755     if (local_err) {
 756         error_propagate(errp, local_err);
 757         vmstate_loading = false;
 758         qemu_mutex_unlock_iothread();
 759         return;
 760     }
 761
 762     /* discard colo disk buffer */
 763     replication_do_checkpoint_all(&local_err);
 764     if (local_err) {
 765         error_propagate(errp, local_err);
 766         vmstate_loading = false;
 767         qemu_mutex_unlock_iothread();
 768         return;
 769     }
 770 #else
 771     abort();
 772 #endif
 773     /* Notify all filters of all NIC to do checkpoint */
 774     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, &local_err);
 775
 776     if (local_err) {
 777         error_propagate(errp, local_err);
 778         vmstate_loading = false;
 779         qemu_mutex_unlock_iothread();
 780         return;
 781     }
 782
 783     vmstate_loading = false;
 784     vm_start();
 785     trace_colo_vm_state_change("stop", "run");
 786     qemu_mutex_unlock_iothread();
 787
 788     if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 789         return;
 790     }
 791
 792     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
 793                  &local_err);
 794     error_propagate(errp, local_err);
 795 }
 796
 797 static void colo_wait_handle_message(MigrationIncomingState *mis,
 798                 QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
 799 {
 800     COLOMessage msg;
 801     Error *local_err = NULL;
 802
 803     msg = colo_receive_message(mis->from_src_file, &local_err);
 804     if (local_err) {
 805         error_propagate(errp, local_err);
 806         return;
 807     }
 808
 809     switch (msg) {
 810     case COLO_MESSAGE_CHECKPOINT_REQUEST:
 811         colo_incoming_process_checkpoint(mis, fb, bioc, errp);
 812         break;
 813     default:
 814         error_setg(errp, "Got unknown COLO message: %d", msg);
 815         break;
 816     }
 817 }
 818
 819 void *colo_process_incoming_thread(void *opaque)
 820 {
 821     MigrationIncomingState *mis = opaque;
 822     QEMUFile *fb = NULL;
 823     QIOChannelBuffer *bioc = NULL; /* Cache incoming device state */
 824     Error *local_err = NULL;
 825
 826     rcu_register_thread();
 827     qemu_sem_init(&mis->colo_incoming_sem, 0);
 828
 829     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
 830                       MIGRATION_STATUS_COLO);
 831
 832     last_colo_mode = get_colo_mode();
 833     if (last_colo_mode != COLO_MODE_SECONDARY) {
 834         error_report("COLO mode must be COLO_MODE_SECONDARY");
 835         return NULL;
 836     }
 837
 838     failover_init_state();
 839
 840     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
 841     if (!mis->to_src_file) {
 842         error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
 843         goto out;
 844     }
 845     /*
 846      * Note: the communication between Primary side and Secondary side
 847      * should be sequential, we set the fd to unblocked in migration incoming
 848      * coroutine, and here we are in the COLO incoming thread, so it is ok to
 849      * set the fd back to blocked.
 850      */
 851     qemu_file_set_blocking(mis->from_src_file, true);
 852
 853     colo_incoming_start_dirty_log();
 854
 855     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 856     fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
 857     object_unref(OBJECT(bioc));
 858
 859     qemu_mutex_lock_iothread();
 860 #ifdef CONFIG_REPLICATION
 861     replication_start_all(REPLICATION_MODE_SECONDARY, &local_err);
 862     if (local_err) {
 863         qemu_mutex_unlock_iothread();
 864         goto out;
 865     }
 866 #else
 867         abort();
 868 #endif
 869     vm_start();
 870     trace_colo_vm_state_change("stop", "run");
 871     qemu_mutex_unlock_iothread();
 872
 873     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
 874                       &local_err);
 875     if (local_err) {
 876         goto out;
 877     }
 878
 879     while (mis->state == MIGRATION_STATUS_COLO) {
 880         colo_wait_handle_message(mis, fb, bioc, &local_err);
 881         if (local_err) {
 882             error_report_err(local_err);
 883             break;
 884         }
 885
 886         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 887             failover_set_state(FAILOVER_STATUS_RELAUNCH,
 888                             FAILOVER_STATUS_NONE);
 889             failover_request_active(NULL);
 890             break;
 891         }
 892
 893         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 894             error_report("failover request");
 895             break;
 896         }
 897     }
 898
 899 out:
 900     /*
 901      * There are only two reasons we can get here, some error happened
 902      * or the user triggered failover.
 903      */
 904     switch (failover_get_state()) {
 905     case FAILOVER_STATUS_COMPLETED:
 906         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
 907                                   COLO_EXIT_REASON_REQUEST);
 908         break;
 909     default:
 910         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
 911                                   COLO_EXIT_REASON_ERROR);
 912     }
 913
 914     if (fb) {
 915         qemu_fclose(fb);
 916     }
 917
 918     /* Hope this not to be too long to loop here */
 919     qemu_sem_wait(&mis->colo_incoming_sem);
 920     qemu_sem_destroy(&mis->colo_incoming_sem);
 921     /* Must be called after failover BH is completed */
 922     if (mis->to_src_file) {
 923         qemu_fclose(mis->to_src_file);
 924         mis->to_src_file = NULL;
 925     }
 926
 927     rcu_unregister_thread();
 928     return NULL;
 929 }