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 //#define DEBUG_MIGRATION
  30
  31 #ifdef DEBUG_MIGRATION
  32 #define DPRINTF(fmt, ...) \
  33     do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)
  34 #else
  35 #define DPRINTF(fmt, ...) \
  36     do { } while (0)
  37 #endif
  38
  39 enum {
  40     MIG_STATE_ERROR = -1,
  41     MIG_STATE_NONE,
  42     MIG_STATE_SETUP,
  43     MIG_STATE_CANCELLING,
  44     MIG_STATE_CANCELLED,
  45     MIG_STATE_ACTIVE,
  46     MIG_STATE_COMPLETED,
  47 };
  48
  49 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
  50
  51 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
  52  * data. */
  53 #define BUFFER_DELAY     100
  54 #define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
  55
  56 /* Migration XBZRLE default cache size */
  57 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
  58
  59 static NotifierList migration_state_notifiers =
  60     NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
  61
  62 /* When we add fault tolerance, we could have several
  63    migrations at once.  For now we don't need to add
  64    dynamic creation of migration */
  65
  66 MigrationState *migrate_get_current(void)
  67 {
  68     static MigrationState current_migration = {
  69         .state = MIG_STATE_NONE,
  70         .bandwidth_limit = MAX_THROTTLE,
  71         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
  72         .mbps = -1,
  73     };
  74
  75     return &current_migration;
  76 }
  77
  78 void qemu_start_incoming_migration(const char *uri, Error **errp)
  79 {
  80     const char *p;
  81
  82     if (strstart(uri, "tcp:", &p))
  83         tcp_start_incoming_migration(p, errp);
  84 #ifdef CONFIG_RDMA
  85     else if (strstart(uri, "rdma:", &p))
  86         rdma_start_incoming_migration(p, errp);
  87 #endif
  88 #if !defined(WIN32)
  89     else if (strstart(uri, "exec:", &p))
  90         exec_start_incoming_migration(p, errp);
  91     else if (strstart(uri, "unix:", &p))
  92         unix_start_incoming_migration(p, errp);
  93     else if (strstart(uri, "fd:", &p))
  94         fd_start_incoming_migration(p, errp);
  95 #endif
  96     else {
  97         error_setg(errp, "unknown migration protocol: %s", uri);
  98     }
  99 }
 100
 101 static void process_incoming_migration_co(void *opaque)
 102 {
 103     QEMUFile *f = opaque;
 104     int ret;
 105
 106     ret = qemu_loadvm_state(f);
 107     qemu_fclose(f);
 108     free_xbzrle_decoded_buf();
 109     if (ret < 0) {
 110         fprintf(stderr, "load of migration failed\n");
 111         exit(EXIT_FAILURE);
 112     }
 113     qemu_announce_self();
 114     DPRINTF("successfully loaded vm state\n");
 115
 116     bdrv_clear_incoming_migration_all();
 117     /* Make sure all file formats flush their mutable metadata */
 118     bdrv_invalidate_cache_all();
 119
 120     if (autostart) {
 121         vm_start();
 122     } else {
 123         runstate_set(RUN_STATE_PAUSED);
 124     }
 125 }
 126
 127 void process_incoming_migration(QEMUFile *f)
 128 {
 129     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 130     int fd = qemu_get_fd(f);
 131
 132     assert(fd != -1);
 133     qemu_set_nonblock(fd);
 134     qemu_coroutine_enter(co, f);
 135 }
 136
 137 /* amount of nanoseconds we are willing to wait for migration to be down.
 138  * the choice of nanoseconds is because it is the maximum resolution that
 139  * get_clock() can achieve. It is an internal measure. All user-visible
 140  * units must be in seconds */
 141 static uint64_t max_downtime = 30000000;
 142
 143 uint64_t migrate_max_downtime(void)
 144 {
 145     return max_downtime;
 146 }
 147
 148 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 149 {
 150     MigrationCapabilityStatusList *head = NULL;
 151     MigrationCapabilityStatusList *caps;
 152     MigrationState *s = migrate_get_current();
 153     int i;
 154
 155     caps = NULL; /* silence compiler warning */
 156     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 157         if (head == NULL) {
 158             head = g_malloc0(sizeof(*caps));
 159             caps = head;
 160         } else {
 161             caps->next = g_malloc0(sizeof(*caps));
 162             caps = caps->next;
 163         }
 164         caps->value =
 165             g_malloc(sizeof(*caps->value));
 166         caps->value->capability = i;
 167         caps->value->state = s->enabled_capabilities[i];
 168     }
 169
 170     return head;
 171 }
 172
 173 static void get_xbzrle_cache_stats(MigrationInfo *info)
 174 {
 175     if (migrate_use_xbzrle()) {
 176         info->has_xbzrle_cache = true;
 177         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 178         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 179         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 180         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 181         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 182         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 183     }
 184 }
 185
 186 MigrationInfo *qmp_query_migrate(Error **errp)
 187 {
 188     MigrationInfo *info = g_malloc0(sizeof(*info));
 189     MigrationState *s = migrate_get_current();
 190
 191     switch (s->state) {
 192     case MIG_STATE_NONE:
 193         /* no migration has happened ever */
 194         break;
 195     case MIG_STATE_SETUP:
 196         info->has_status = true;
 197         info->status = g_strdup("setup");
 198         info->has_total_time = false;
 199         break;
 200     case MIG_STATE_ACTIVE:
 201     case MIG_STATE_CANCELLING:
 202         info->has_status = true;
 203         info->status = g_strdup("active");
 204         info->has_total_time = true;
 205         info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
 206             - s->total_time;
 207         info->has_expected_downtime = true;
 208         info->expected_downtime = s->expected_downtime;
 209         info->has_setup_time = true;
 210         info->setup_time = s->setup_time;
 211
 212         info->has_ram = true;
 213         info->ram = g_malloc0(sizeof(*info->ram));
 214         info->ram->transferred = ram_bytes_transferred();
 215         info->ram->remaining = ram_bytes_remaining();
 216         info->ram->total = ram_bytes_total();
 217         info->ram->duplicate = dup_mig_pages_transferred();
 218         info->ram->skipped = skipped_mig_pages_transferred();
 219         info->ram->normal = norm_mig_pages_transferred();
 220         info->ram->normal_bytes = norm_mig_bytes_transferred();
 221         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 222         info->ram->mbps = s->mbps;
 223
 224         if (blk_mig_active()) {
 225             info->has_disk = true;
 226             info->disk = g_malloc0(sizeof(*info->disk));
 227             info->disk->transferred = blk_mig_bytes_transferred();
 228             info->disk->remaining = blk_mig_bytes_remaining();
 229             info->disk->total = blk_mig_bytes_total();
 230         }
 231
 232         get_xbzrle_cache_stats(info);
 233         break;
 234     case MIG_STATE_COMPLETED:
 235         get_xbzrle_cache_stats(info);
 236
 237         info->has_status = true;
 238         info->status = g_strdup("completed");
 239         info->has_total_time = true;
 240         info->total_time = s->total_time;
 241         info->has_downtime = true;
 242         info->downtime = s->downtime;
 243         info->has_setup_time = true;
 244         info->setup_time = s->setup_time;
 245
 246         info->has_ram = true;
 247         info->ram = g_malloc0(sizeof(*info->ram));
 248         info->ram->transferred = ram_bytes_transferred();
 249         info->ram->remaining = 0;
 250         info->ram->total = ram_bytes_total();
 251         info->ram->duplicate = dup_mig_pages_transferred();
 252         info->ram->skipped = skipped_mig_pages_transferred();
 253         info->ram->normal = norm_mig_pages_transferred();
 254         info->ram->normal_bytes = norm_mig_bytes_transferred();
 255         info->ram->mbps = s->mbps;
 256         break;
 257     case MIG_STATE_ERROR:
 258         info->has_status = true;
 259         info->status = g_strdup("failed");
 260         break;
 261     case MIG_STATE_CANCELLED:
 262         info->has_status = true;
 263         info->status = g_strdup("cancelled");
 264         break;
 265     }
 266
 267     return info;
 268 }
 269
 270 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 271                                   Error **errp)
 272 {
 273     MigrationState *s = migrate_get_current();
 274     MigrationCapabilityStatusList *cap;
 275
 276     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
 277         error_set(errp, QERR_MIGRATION_ACTIVE);
 278         return;
 279     }
 280
 281     for (cap = params; cap; cap = cap->next) {
 282         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 283     }
 284 }
 285
 286 /* shared migration helpers */
 287
 288 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 289 {
 290     if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
 291         trace_migrate_set_state(new_state);
 292     }
 293 }
 294
 295 static void migrate_fd_cleanup(void *opaque)
 296 {
 297     MigrationState *s = opaque;
 298
 299     qemu_bh_delete(s->cleanup_bh);
 300     s->cleanup_bh = NULL;
 301
 302     if (s->file) {
 303         DPRINTF("closing file\n");
 304         qemu_mutex_unlock_iothread();
 305         qemu_thread_join(&s->thread);
 306         qemu_mutex_lock_iothread();
 307
 308         qemu_fclose(s->file);
 309         s->file = NULL;
 310     }
 311
 312     assert(s->state != MIG_STATE_ACTIVE);
 313
 314     if (s->state != MIG_STATE_COMPLETED) {
 315         qemu_savevm_state_cancel();
 316         if (s->state == MIG_STATE_CANCELLING) {
 317             migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
 318         }
 319     }
 320
 321     notifier_list_notify(&migration_state_notifiers, s);
 322 }
 323
 324 void migrate_fd_error(MigrationState *s)
 325 {
 326     DPRINTF("setting error state\n");
 327     assert(s->file == NULL);
 328     s->state = MIG_STATE_ERROR;
 329     trace_migrate_set_state(MIG_STATE_ERROR);
 330     notifier_list_notify(&migration_state_notifiers, s);
 331 }
 332
 333 static void migrate_fd_cancel(MigrationState *s)
 334 {
 335     int old_state ;
 336     DPRINTF("cancelling migration\n");
 337
 338     do {
 339         old_state = s->state;
 340         if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
 341             break;
 342         }
 343         migrate_set_state(s, old_state, MIG_STATE_CANCELLING);
 344     } while (s->state != MIG_STATE_CANCELLING);
 345 }
 346
 347 void add_migration_state_change_notifier(Notifier *notify)
 348 {
 349     notifier_list_add(&migration_state_notifiers, notify);
 350 }
 351
 352 void remove_migration_state_change_notifier(Notifier *notify)
 353 {
 354     notifier_remove(notify);
 355 }
 356
 357 bool migration_in_setup(MigrationState *s)
 358 {
 359     return s->state == MIG_STATE_SETUP;
 360 }
 361
 362 bool migration_has_finished(MigrationState *s)
 363 {
 364     return s->state == MIG_STATE_COMPLETED;
 365 }
 366
 367 bool migration_has_failed(MigrationState *s)
 368 {
 369     return (s->state == MIG_STATE_CANCELLED ||
 370             s->state == MIG_STATE_ERROR);
 371 }
 372
 373 static MigrationState *migrate_init(const MigrationParams *params)
 374 {
 375     MigrationState *s = migrate_get_current();
 376     int64_t bandwidth_limit = s->bandwidth_limit;
 377     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 378     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 379
 380     memcpy(enabled_capabilities, s->enabled_capabilities,
 381            sizeof(enabled_capabilities));
 382
 383     memset(s, 0, sizeof(*s));
 384     s->params = *params;
 385     memcpy(s->enabled_capabilities, enabled_capabilities,
 386            sizeof(enabled_capabilities));
 387     s->xbzrle_cache_size = xbzrle_cache_size;
 388
 389     s->bandwidth_limit = bandwidth_limit;
 390     s->state = MIG_STATE_SETUP;
 391     trace_migrate_set_state(MIG_STATE_SETUP);
 392
 393     s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 394     return s;
 395 }
 396
 397 static GSList *migration_blockers;
 398
 399 void migrate_add_blocker(Error *reason)
 400 {
 401     migration_blockers = g_slist_prepend(migration_blockers, reason);
 402 }
 403
 404 void migrate_del_blocker(Error *reason)
 405 {
 406     migration_blockers = g_slist_remove(migration_blockers, reason);
 407 }
 408
 409 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 410                  bool has_inc, bool inc, bool has_detach, bool detach,
 411                  Error **errp)
 412 {
 413     Error *local_err = NULL;
 414     MigrationState *s = migrate_get_current();
 415     MigrationParams params;
 416     const char *p;
 417
 418     params.blk = has_blk && blk;
 419     params.shared = has_inc && inc;
 420
 421     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
 422         s->state == MIG_STATE_CANCELLING) {
 423         error_set(errp, QERR_MIGRATION_ACTIVE);
 424         return;
 425     }
 426
 427     if (qemu_savevm_state_blocked(errp)) {
 428         return;
 429     }
 430
 431     if (migration_blockers) {
 432         *errp = error_copy(migration_blockers->data);
 433         return;
 434     }
 435
 436     s = migrate_init(&params);
 437
 438     if (strstart(uri, "tcp:", &p)) {
 439         tcp_start_outgoing_migration(s, p, &local_err);
 440 #ifdef CONFIG_RDMA
 441     } else if (strstart(uri, "rdma:", &p)) {
 442         rdma_start_outgoing_migration(s, p, &local_err);
 443 #endif
 444 #if !defined(WIN32)
 445     } else if (strstart(uri, "exec:", &p)) {
 446         exec_start_outgoing_migration(s, p, &local_err);
 447     } else if (strstart(uri, "unix:", &p)) {
 448         unix_start_outgoing_migration(s, p, &local_err);
 449     } else if (strstart(uri, "fd:", &p)) {
 450         fd_start_outgoing_migration(s, p, &local_err);
 451 #endif
 452     } else {
 453         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 454         s->state = MIG_STATE_ERROR;
 455         return;
 456     }
 457
 458     if (local_err) {
 459         migrate_fd_error(s);
 460         error_propagate(errp, local_err);
 461         return;
 462     }
 463 }
 464
 465 void qmp_migrate_cancel(Error **errp)
 466 {
 467     migrate_fd_cancel(migrate_get_current());
 468 }
 469
 470 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 471 {
 472     MigrationState *s = migrate_get_current();
 473     int64_t new_size;
 474
 475     /* Check for truncation */
 476     if (value != (size_t)value) {
 477         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 478                   "exceeding address space");
 479         return;
 480     }
 481
 482     /* Cache should not be larger than guest ram size */
 483     if (value > ram_bytes_total()) {
 484         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 485                   "exceeds guest ram size ");
 486         return;
 487     }
 488
 489     new_size = xbzrle_cache_resize(value);
 490     if (new_size < 0) {
 491         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 492                   "is smaller than page size");
 493         return;
 494     }
 495
 496     s->xbzrle_cache_size = new_size;
 497 }
 498
 499 int64_t qmp_query_migrate_cache_size(Error **errp)
 500 {
 501     return migrate_xbzrle_cache_size();
 502 }
 503
 504 void qmp_migrate_set_speed(int64_t value, Error **errp)
 505 {
 506     MigrationState *s;
 507
 508     if (value < 0) {
 509         value = 0;
 510     }
 511     if (value > SIZE_MAX) {
 512         value = SIZE_MAX;
 513     }
 514
 515     s = migrate_get_current();
 516     s->bandwidth_limit = value;
 517     if (s->file) {
 518         qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
 519     }
 520 }
 521
 522 void qmp_migrate_set_downtime(double value, Error **errp)
 523 {
 524     value *= 1e9;
 525     value = MAX(0, MIN(UINT64_MAX, value));
 526     max_downtime = (uint64_t)value;
 527 }
 528
 529 bool migrate_rdma_pin_all(void)
 530 {
 531     MigrationState *s;
 532
 533     s = migrate_get_current();
 534
 535     return s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL];
 536 }
 537
 538 bool migrate_auto_converge(void)
 539 {
 540     MigrationState *s;
 541
 542     s = migrate_get_current();
 543
 544     return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
 545 }
 546
 547 bool migrate_zero_blocks(void)
 548 {
 549     MigrationState *s;
 550
 551     s = migrate_get_current();
 552
 553     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 554 }
 555
 556 int migrate_use_xbzrle(void)
 557 {
 558     MigrationState *s;
 559
 560     s = migrate_get_current();
 561
 562     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 563 }
 564
 565 int64_t migrate_xbzrle_cache_size(void)
 566 {
 567     MigrationState *s;
 568
 569     s = migrate_get_current();
 570
 571     return s->xbzrle_cache_size;
 572 }
 573
 574 /* migration thread support */
 575
 576 static void *migration_thread(void *opaque)
 577 {
 578     MigrationState *s = opaque;
 579     int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 580     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 581     int64_t initial_bytes = 0;
 582     int64_t max_size = 0;
 583     int64_t start_time = initial_time;
 584     bool old_vm_running = false;
 585
 586     DPRINTF("beginning savevm\n");
 587     qemu_savevm_state_begin(s->file, &s->params);
 588
 589     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
 590     migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
 591
 592     DPRINTF("setup complete\n");
 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             DPRINTF("iterate\n");
 600             pending_size = qemu_savevm_state_pending(s->file, max_size);
 601             DPRINTF("pending size %" PRIu64 " max %" PRIu64 "\n",
 602                     pending_size, max_size);
 603             if (pending_size && pending_size >= max_size) {
 604                 qemu_savevm_state_iterate(s->file);
 605             } else {
 606                 int ret;
 607
 608                 DPRINTF("done iterating\n");
 609                 qemu_mutex_lock_iothread();
 610                 start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 611                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 612                 old_vm_running = runstate_is_running();
 613
 614                 ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 615                 if (ret >= 0) {
 616                     qemu_file_set_rate_limit(s->file, INT64_MAX);
 617                     qemu_savevm_state_complete(s->file);
 618                 }
 619                 qemu_mutex_unlock_iothread();
 620
 621                 if (ret < 0) {
 622                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 623                     break;
 624                 }
 625
 626                 if (!qemu_file_get_error(s->file)) {
 627                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
 628                     break;
 629                 }
 630             }
 631         }
 632
 633         if (qemu_file_get_error(s->file)) {
 634             migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 635             break;
 636         }
 637         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 638         if (current_time >= initial_time + BUFFER_DELAY) {
 639             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
 640             uint64_t time_spent = current_time - initial_time;
 641             double bandwidth = transferred_bytes / time_spent;
 642             max_size = bandwidth * migrate_max_downtime() / 1000000;
 643
 644             s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
 645                     ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
 646
 647             DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64
 648                     " bandwidth %g max_size %" PRId64 "\n",
 649                     transferred_bytes, time_spent, bandwidth, max_size);
 650             /* if we haven't sent anything, we don't want to recalculate
 651                10000 is a small enough number for our purposes */
 652             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 653                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 654             }
 655
 656             qemu_file_reset_rate_limit(s->file);
 657             initial_time = current_time;
 658             initial_bytes = qemu_ftell(s->file);
 659         }
 660         if (qemu_file_rate_limit(s->file)) {
 661             /* usleep expects microseconds */
 662             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 663         }
 664     }
 665
 666     qemu_mutex_lock_iothread();
 667     if (s->state == MIG_STATE_COMPLETED) {
 668         int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 669         s->total_time = end_time - s->total_time;
 670         s->downtime = end_time - start_time;
 671         runstate_set(RUN_STATE_POSTMIGRATE);
 672     } else {
 673         if (old_vm_running) {
 674             vm_start();
 675         }
 676     }
 677     qemu_bh_schedule(s->cleanup_bh);
 678     qemu_mutex_unlock_iothread();
 679
 680     return NULL;
 681 }
 682
 683 void migrate_fd_connect(MigrationState *s)
 684 {
 685     s->state = MIG_STATE_SETUP;
 686     trace_migrate_set_state(MIG_STATE_SETUP);
 687
 688     /* This is a best 1st approximation. ns to ms */
 689     s->expected_downtime = max_downtime/1000000;
 690     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 691
 692     qemu_file_set_rate_limit(s->file,
 693                              s->bandwidth_limit / XFER_LIMIT_RATIO);
 694
 695     /* Notify before starting migration thread */
 696     notifier_list_notify(&migration_state_notifiers, s);
 697
 698     qemu_thread_create(&s->thread, "migration", migration_thread, s,
 699                        QEMU_THREAD_JOINABLE);
 700 }