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