migration.c

   1 /*
   2  * QEMU live migration
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "qemu/main-loop.h"
  18 #include "migration/migration.h"
  19 #include "monitor/monitor.h"
  20 #include "migration/qemu-file.h"
  21 #include "sysemu/sysemu.h"
  22 #include "block/block.h"
  23 #include "qemu/sockets.h"
  24 #include "migration/block.h"
  25 #include "qemu/thread.h"
  26 #include "qmp-commands.h"
  27 #include "trace.h"
  28
  29 enum {
  30     MIG_STATE_ERROR = -1,
  31     MIG_STATE_NONE,
  32     MIG_STATE_SETUP,
  33     MIG_STATE_CANCELLING,
  34     MIG_STATE_CANCELLED,
  35     MIG_STATE_ACTIVE,
  36     MIG_STATE_COMPLETED,
  37 };
  38
  39 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
  40
  41 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
  42  * data. */
  43 #define BUFFER_DELAY     100
  44 #define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
  45
  46 /* Migration XBZRLE default cache size */
  47 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
  48
  49 static NotifierList migration_state_notifiers =
  50     NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
  51
  52 /* When we add fault tolerance, we could have several
  53    migrations at once.  For now we don't need to add
  54    dynamic creation of migration */
  55
  56 MigrationState *migrate_get_current(void)
  57 {
  58     static MigrationState current_migration = {
  59         .state = MIG_STATE_NONE,
  60         .bandwidth_limit = MAX_THROTTLE,
  61         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
  62         .mbps = -1,
  63     };
  64
  65     return &current_migration;
  66 }
  67
  68 void qemu_start_incoming_migration(const char *uri, Error **errp)
  69 {
  70     const char *p;
  71
  72     if (strstart(uri, "tcp:", &p))
  73         tcp_start_incoming_migration(p, errp);
  74 #ifdef CONFIG_RDMA
  75     else if (strstart(uri, "rdma:", &p))
  76         rdma_start_incoming_migration(p, errp);
  77 #endif
  78 #if !defined(WIN32)
  79     else if (strstart(uri, "exec:", &p))
  80         exec_start_incoming_migration(p, errp);
  81     else if (strstart(uri, "unix:", &p))
  82         unix_start_incoming_migration(p, errp);
  83     else if (strstart(uri, "fd:", &p))
  84         fd_start_incoming_migration(p, errp);
  85 #endif
  86     else {
  87         error_setg(errp, "unknown migration protocol: %s", uri);
  88     }
  89 }
  90
  91 static void process_incoming_migration_co(void *opaque)
  92 {
  93     QEMUFile *f = opaque;
  94     Error *local_err = NULL;
  95     int ret;
  96
  97     ret = qemu_loadvm_state(f);
  98     qemu_fclose(f);
  99     free_xbzrle_decoded_buf();
 100     if (ret < 0) {
 101         fprintf(stderr, "load of migration failed\n");
 102         exit(EXIT_FAILURE);
 103     }
 104     qemu_announce_self();
 105
 106     bdrv_clear_incoming_migration_all();
 107     /* Make sure all file formats flush their mutable metadata */
 108     bdrv_invalidate_cache_all(&local_err);
 109     if (local_err) {
 110         qerror_report_err(local_err);
 111         error_free(local_err);
 112         exit(EXIT_FAILURE);
 113     }
 114
 115     if (autostart) {
 116         vm_start();
 117     } else {
 118         runstate_set(RUN_STATE_PAUSED);
 119     }
 120 }
 121
 122 void process_incoming_migration(QEMUFile *f)
 123 {
 124     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 125     int fd = qemu_get_fd(f);
 126
 127     assert(fd != -1);
 128     qemu_set_nonblock(fd);
 129     qemu_coroutine_enter(co, f);
 130 }
 131
 132 /* amount of nanoseconds we are willing to wait for migration to be down.
 133  * the choice of nanoseconds is because it is the maximum resolution that
 134  * get_clock() can achieve. It is an internal measure. All user-visible
 135  * units must be in seconds */
 136 static uint64_t max_downtime = 30000000;
 137
 138 uint64_t migrate_max_downtime(void)
 139 {
 140     return max_downtime;
 141 }
 142
 143 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 144 {
 145     MigrationCapabilityStatusList *head = NULL;
 146     MigrationCapabilityStatusList *caps;
 147     MigrationState *s = migrate_get_current();
 148     int i;
 149
 150     caps = NULL; /* silence compiler warning */
 151     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 152         if (head == NULL) {
 153             head = g_malloc0(sizeof(*caps));
 154             caps = head;
 155         } else {
 156             caps->next = g_malloc0(sizeof(*caps));
 157             caps = caps->next;
 158         }
 159         caps->value =
 160             g_malloc(sizeof(*caps->value));
 161         caps->value->capability = i;
 162         caps->value->state = s->enabled_capabilities[i];
 163     }
 164
 165     return head;
 166 }
 167
 168 static void get_xbzrle_cache_stats(MigrationInfo *info)
 169 {
 170     if (migrate_use_xbzrle()) {
 171         info->has_xbzrle_cache = true;
 172         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 173         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 174         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 175         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 176         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 177         info->xbzrle_cache->cache_miss_rate = xbzrle_mig_cache_miss_rate();
 178         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 179     }
 180 }
 181
 182 MigrationInfo *qmp_query_migrate(Error **errp)
 183 {
 184     MigrationInfo *info = g_malloc0(sizeof(*info));
 185     MigrationState *s = migrate_get_current();
 186
 187     switch (s->state) {
 188     case MIG_STATE_NONE:
 189         /* no migration has happened ever */
 190         break;
 191     case MIG_STATE_SETUP:
 192         info->has_status = true;
 193         info->status = g_strdup("setup");
 194         info->has_total_time = false;
 195         break;
 196     case MIG_STATE_ACTIVE:
 197     case MIG_STATE_CANCELLING:
 198         info->has_status = true;
 199         info->status = g_strdup("active");
 200         info->has_total_time = true;
 201         info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
 202             - s->total_time;
 203         info->has_expected_downtime = true;
 204         info->expected_downtime = s->expected_downtime;
 205         info->has_setup_time = true;
 206         info->setup_time = s->setup_time;
 207
 208         info->has_ram = true;
 209         info->ram = g_malloc0(sizeof(*info->ram));
 210         info->ram->transferred = ram_bytes_transferred();
 211         info->ram->remaining = ram_bytes_remaining();
 212         info->ram->total = ram_bytes_total();
 213         info->ram->duplicate = dup_mig_pages_transferred();
 214         info->ram->skipped = skipped_mig_pages_transferred();
 215         info->ram->normal = norm_mig_pages_transferred();
 216         info->ram->normal_bytes = norm_mig_bytes_transferred();
 217         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 218         info->ram->mbps = s->mbps;
 219         info->ram->dirty_sync_count = s->dirty_sync_count;
 220
 221         if (blk_mig_active()) {
 222             info->has_disk = true;
 223             info->disk = g_malloc0(sizeof(*info->disk));
 224             info->disk->transferred = blk_mig_bytes_transferred();
 225             info->disk->remaining = blk_mig_bytes_remaining();
 226             info->disk->total = blk_mig_bytes_total();
 227         }
 228
 229         get_xbzrle_cache_stats(info);
 230         break;
 231     case MIG_STATE_COMPLETED:
 232         get_xbzrle_cache_stats(info);
 233
 234         info->has_status = true;
 235         info->status = g_strdup("completed");
 236         info->has_total_time = true;
 237         info->total_time = s->total_time;
 238         info->has_downtime = true;
 239         info->downtime = s->downtime;
 240         info->has_setup_time = true;
 241         info->setup_time = s->setup_time;
 242
 243         info->has_ram = true;
 244         info->ram = g_malloc0(sizeof(*info->ram));
 245         info->ram->transferred = ram_bytes_transferred();
 246         info->ram->remaining = 0;
 247         info->ram->total = ram_bytes_total();
 248         info->ram->duplicate = dup_mig_pages_transferred();
 249         info->ram->skipped = skipped_mig_pages_transferred();
 250         info->ram->normal = norm_mig_pages_transferred();
 251         info->ram->normal_bytes = norm_mig_bytes_transferred();
 252         info->ram->mbps = s->mbps;
 253         info->ram->dirty_sync_count = s->dirty_sync_count;
 254         break;
 255     case MIG_STATE_ERROR:
 256         info->has_status = true;
 257         info->status = g_strdup("failed");
 258         break;
 259     case MIG_STATE_CANCELLED:
 260         info->has_status = true;
 261         info->status = g_strdup("cancelled");
 262         break;
 263     }
 264
 265     return info;
 266 }
 267
 268 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 269                                   Error **errp)
 270 {
 271     MigrationState *s = migrate_get_current();
 272     MigrationCapabilityStatusList *cap;
 273
 274     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
 275         error_set(errp, QERR_MIGRATION_ACTIVE);
 276         return;
 277     }
 278
 279     for (cap = params; cap; cap = cap->next) {
 280         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 281     }
 282 }
 283
 284 /* shared migration helpers */
 285
 286 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 287 {
 288     if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
 289         trace_migrate_set_state(new_state);
 290     }
 291 }
 292
 293 static void migrate_fd_cleanup(void *opaque)
 294 {
 295     MigrationState *s = opaque;
 296
 297     qemu_bh_delete(s->cleanup_bh);
 298     s->cleanup_bh = NULL;
 299
 300     if (s->file) {
 301         trace_migrate_fd_cleanup();
 302         qemu_mutex_unlock_iothread();
 303         qemu_thread_join(&s->thread);
 304         qemu_mutex_lock_iothread();
 305
 306         qemu_fclose(s->file);
 307         s->file = NULL;
 308     }
 309
 310     assert(s->state != MIG_STATE_ACTIVE);
 311
 312     if (s->state != MIG_STATE_COMPLETED) {
 313         qemu_savevm_state_cancel();
 314         if (s->state == MIG_STATE_CANCELLING) {
 315             migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
 316         }
 317     }
 318
 319     notifier_list_notify(&migration_state_notifiers, s);
 320 }
 321
 322 void migrate_fd_error(MigrationState *s)
 323 {
 324     trace_migrate_fd_error();
 325     assert(s->file == NULL);
 326     s->state = MIG_STATE_ERROR;
 327     trace_migrate_set_state(MIG_STATE_ERROR);
 328     notifier_list_notify(&migration_state_notifiers, s);
 329 }
 330
 331 static void migrate_fd_cancel(MigrationState *s)
 332 {
 333     int old_state ;
 334     trace_migrate_fd_cancel();
 335
 336     do {
 337         old_state = s->state;
 338         if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
 339             break;
 340         }
 341         migrate_set_state(s, old_state, MIG_STATE_CANCELLING);
 342     } while (s->state != MIG_STATE_CANCELLING);
 343 }
 344
 345 void add_migration_state_change_notifier(Notifier *notify)
 346 {
 347     notifier_list_add(&migration_state_notifiers, notify);
 348 }
 349
 350 void remove_migration_state_change_notifier(Notifier *notify)
 351 {
 352     notifier_remove(notify);
 353 }
 354
 355 bool migration_in_setup(MigrationState *s)
 356 {
 357     return s->state == MIG_STATE_SETUP;
 358 }
 359
 360 bool migration_has_finished(MigrationState *s)
 361 {
 362     return s->state == MIG_STATE_COMPLETED;
 363 }
 364
 365 bool migration_has_failed(MigrationState *s)
 366 {
 367     return (s->state == MIG_STATE_CANCELLED ||
 368             s->state == MIG_STATE_ERROR);
 369 }
 370
 371 static MigrationState *migrate_init(const MigrationParams *params)
 372 {
 373     MigrationState *s = migrate_get_current();
 374     int64_t bandwidth_limit = s->bandwidth_limit;
 375     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 376     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 377
 378     memcpy(enabled_capabilities, s->enabled_capabilities,
 379            sizeof(enabled_capabilities));
 380
 381     memset(s, 0, sizeof(*s));
 382     s->params = *params;
 383     memcpy(s->enabled_capabilities, enabled_capabilities,
 384            sizeof(enabled_capabilities));
 385     s->xbzrle_cache_size = xbzrle_cache_size;
 386
 387     s->bandwidth_limit = bandwidth_limit;
 388     s->state = MIG_STATE_SETUP;
 389     trace_migrate_set_state(MIG_STATE_SETUP);
 390
 391     s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 392     return s;
 393 }
 394
 395 static GSList *migration_blockers;
 396
 397 void migrate_add_blocker(Error *reason)
 398 {
 399     migration_blockers = g_slist_prepend(migration_blockers, reason);
 400 }
 401
 402 void migrate_del_blocker(Error *reason)
 403 {
 404     migration_blockers = g_slist_remove(migration_blockers, reason);
 405 }
 406
 407 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 408                  bool has_inc, bool inc, bool has_detach, bool detach,
 409                  Error **errp)
 410 {
 411     Error *local_err = NULL;
 412     MigrationState *s = migrate_get_current();
 413     MigrationParams params;
 414     const char *p;
 415
 416     params.blk = has_blk && blk;
 417     params.shared = has_inc && inc;
 418
 419     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
 420         s->state == MIG_STATE_CANCELLING) {
 421         error_set(errp, QERR_MIGRATION_ACTIVE);
 422         return;
 423     }
 424
 425     if (runstate_check(RUN_STATE_INMIGRATE)) {
 426         error_setg(errp, "Guest is waiting for an incoming migration");
 427         return;
 428     }
 429
 430     if (qemu_savevm_state_blocked(errp)) {
 431         return;
 432     }
 433
 434     if (migration_blockers) {
 435         *errp = error_copy(migration_blockers->data);
 436         return;
 437     }
 438
 439     s = migrate_init(&params);
 440
 441     if (strstart(uri, "tcp:", &p)) {
 442         tcp_start_outgoing_migration(s, p, &local_err);
 443 #ifdef CONFIG_RDMA
 444     } else if (strstart(uri, "rdma:", &p)) {
 445         rdma_start_outgoing_migration(s, p, &local_err);
 446 #endif
 447 #if !defined(WIN32)
 448     } else if (strstart(uri, "exec:", &p)) {
 449         exec_start_outgoing_migration(s, p, &local_err);
 450     } else if (strstart(uri, "unix:", &p)) {
 451         unix_start_outgoing_migration(s, p, &local_err);
 452     } else if (strstart(uri, "fd:", &p)) {
 453         fd_start_outgoing_migration(s, p, &local_err);
 454 #endif
 455     } else {
 456         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 457         s->state = MIG_STATE_ERROR;
 458         return;
 459     }
 460
 461     if (local_err) {
 462         migrate_fd_error(s);
 463         error_propagate(errp, local_err);
 464         return;
 465     }
 466 }
 467
 468 void qmp_migrate_cancel(Error **errp)
 469 {
 470     migrate_fd_cancel(migrate_get_current());
 471 }
 472
 473 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 474 {
 475     MigrationState *s = migrate_get_current();
 476     int64_t new_size;
 477
 478     /* Check for truncation */
 479     if (value != (size_t)value) {
 480         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 481                   "exceeding address space");
 482         return;
 483     }
 484
 485     /* Cache should not be larger than guest ram size */
 486     if (value > ram_bytes_total()) {
 487         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 488                   "exceeds guest ram size ");
 489         return;
 490     }
 491
 492     new_size = xbzrle_cache_resize(value);
 493     if (new_size < 0) {
 494         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 495                   "is smaller than page size");
 496         return;
 497     }
 498
 499     s->xbzrle_cache_size = new_size;
 500 }
 501
 502 int64_t qmp_query_migrate_cache_size(Error **errp)
 503 {
 504     return migrate_xbzrle_cache_size();
 505 }
 506
 507 void qmp_migrate_set_speed(int64_t value, Error **errp)
 508 {
 509     MigrationState *s;
 510
 511     if (value < 0) {
 512         value = 0;
 513     }
 514     if (value > SIZE_MAX) {
 515         value = SIZE_MAX;
 516     }
 517
 518     s = migrate_get_current();
 519     s->bandwidth_limit = value;
 520     if (s->file) {
 521         qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
 522     }
 523 }
 524
 525 void qmp_migrate_set_downtime(double value, Error **errp)
 526 {
 527     value *= 1e9;
 528     value = MAX(0, MIN(UINT64_MAX, value));
 529     max_downtime = (uint64_t)value;
 530 }
 531
 532 bool migrate_rdma_pin_all(void)
 533 {
 534     MigrationState *s;
 535
 536     s = migrate_get_current();
 537
 538     return s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL];
 539 }
 540
 541 bool migrate_auto_converge(void)
 542 {
 543     MigrationState *s;
 544
 545     s = migrate_get_current();
 546
 547     return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
 548 }
 549
 550 bool migrate_zero_blocks(void)
 551 {
 552     MigrationState *s;
 553
 554     s = migrate_get_current();
 555
 556     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 557 }
 558
 559 int migrate_use_xbzrle(void)
 560 {
 561     MigrationState *s;
 562
 563     s = migrate_get_current();
 564
 565     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 566 }
 567
 568 int64_t migrate_xbzrle_cache_size(void)
 569 {
 570     MigrationState *s;
 571
 572     s = migrate_get_current();
 573
 574     return s->xbzrle_cache_size;
 575 }
 576
 577 /* migration thread support */
 578
 579 static void *migration_thread(void *opaque)
 580 {
 581     MigrationState *s = opaque;
 582     int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 583     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 584     int64_t initial_bytes = 0;
 585     int64_t max_size = 0;
 586     int64_t start_time = initial_time;
 587     bool old_vm_running = false;
 588
 589     qemu_savevm_state_begin(s->file, &s->params);
 590
 591     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
 592     migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
 593
 594     while (s->state == MIG_STATE_ACTIVE) {
 595         int64_t current_time;
 596         uint64_t pending_size;
 597
 598         if (!qemu_file_rate_limit(s->file)) {
 599             pending_size = qemu_savevm_state_pending(s->file, max_size);
 600             trace_migrate_pending(pending_size, max_size);
 601             if (pending_size && pending_size >= max_size) {
 602                 qemu_savevm_state_iterate(s->file);
 603             } else {
 604                 int ret;
 605
 606                 qemu_mutex_lock_iothread();
 607                 start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 608                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 609                 old_vm_running = runstate_is_running();
 610
 611                 ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 612                 if (ret >= 0) {
 613                     qemu_file_set_rate_limit(s->file, INT64_MAX);
 614                     qemu_savevm_state_complete(s->file);
 615                 }
 616                 qemu_mutex_unlock_iothread();
 617
 618                 if (ret < 0) {
 619                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 620                     break;
 621                 }
 622
 623                 if (!qemu_file_get_error(s->file)) {
 624                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
 625                     break;
 626                 }
 627             }
 628         }
 629
 630         if (qemu_file_get_error(s->file)) {
 631             migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 632             break;
 633         }
 634         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 635         if (current_time >= initial_time + BUFFER_DELAY) {
 636             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
 637             uint64_t time_spent = current_time - initial_time;
 638             double bandwidth = transferred_bytes / time_spent;
 639             max_size = bandwidth * migrate_max_downtime() / 1000000;
 640
 641             s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
 642                     ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
 643
 644             trace_migrate_transferred(transferred_bytes, time_spent,
 645                                       bandwidth, max_size);
 646             /* if we haven't sent anything, we don't want to recalculate
 647                10000 is a small enough number for our purposes */
 648             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 649                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 650             }
 651
 652             qemu_file_reset_rate_limit(s->file);
 653             initial_time = current_time;
 654             initial_bytes = qemu_ftell(s->file);
 655         }
 656         if (qemu_file_rate_limit(s->file)) {
 657             /* usleep expects microseconds */
 658             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 659         }
 660     }
 661
 662     qemu_mutex_lock_iothread();
 663     if (s->state == MIG_STATE_COMPLETED) {
 664         int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 665         s->total_time = end_time - s->total_time;
 666         s->downtime = end_time - start_time;
 667         runstate_set(RUN_STATE_POSTMIGRATE);
 668     } else {
 669         if (old_vm_running) {
 670             vm_start();
 671         }
 672     }
 673     qemu_bh_schedule(s->cleanup_bh);
 674     qemu_mutex_unlock_iothread();
 675
 676     return NULL;
 677 }
 678
 679 void migrate_fd_connect(MigrationState *s)
 680 {
 681     s->state = MIG_STATE_SETUP;
 682     trace_migrate_set_state(MIG_STATE_SETUP);
 683
 684     /* This is a best 1st approximation. ns to ms */
 685     s->expected_downtime = max_downtime/1000000;
 686     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 687
 688     qemu_file_set_rate_limit(s->file,
 689                              s->bandwidth_limit / XFER_LIMIT_RATIO);
 690
 691     /* Notify before starting migration thread */
 692     notifier_list_notify(&migration_state_notifiers, s);
 693
 694     qemu_thread_create(&s->thread, "migration", migration_thread, s,
 695                        QEMU_THREAD_JOINABLE);
 696 }