migration.c

   1 /*
   2  * QEMU live migration
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <[email protected]>
   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, "x-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     if (ret < 0) {
 109         fprintf(stderr, "load of migration failed\n");
 110         exit(EXIT_FAILURE);
 111     }
 112     qemu_announce_self();
 113     DPRINTF("successfully loaded vm state\n");
 114
 115     bdrv_clear_incoming_migration_all();
 116     /* Make sure all file formats flush their mutable metadata */
 117     bdrv_invalidate_cache_all();
 118
 119     if (autostart) {
 120         vm_start();
 121     } else {
 122         runstate_set(RUN_STATE_PAUSED);
 123     }
 124 }
 125
 126 void process_incoming_migration(QEMUFile *f)
 127 {
 128     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 129     int fd = qemu_get_fd(f);
 130
 131     assert(fd != -1);
 132     qemu_set_nonblock(fd);
 133     qemu_coroutine_enter(co, f);
 134 }
 135
 136 /* amount of nanoseconds we are willing to wait for migration to be down.
 137  * the choice of nanoseconds is because it is the maximum resolution that
 138  * get_clock() can achieve. It is an internal measure. All user-visible
 139  * units must be in seconds */
 140 static uint64_t max_downtime = 30000000;
 141
 142 uint64_t migrate_max_downtime(void)
 143 {
 144     return max_downtime;
 145 }
 146
 147 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 148 {
 149     MigrationCapabilityStatusList *head = NULL;
 150     MigrationCapabilityStatusList *caps;
 151     MigrationState *s = migrate_get_current();
 152     int i;
 153
 154     caps = NULL; /* silence compiler warning */
 155     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 156         if (head == NULL) {
 157             head = g_malloc0(sizeof(*caps));
 158             caps = head;
 159         } else {
 160             caps->next = g_malloc0(sizeof(*caps));
 161             caps = caps->next;
 162         }
 163         caps->value =
 164             g_malloc(sizeof(*caps->value));
 165         caps->value->capability = i;
 166         caps->value->state = s->enabled_capabilities[i];
 167     }
 168
 169     return head;
 170 }
 171
 172 static void get_xbzrle_cache_stats(MigrationInfo *info)
 173 {
 174     if (migrate_use_xbzrle()) {
 175         info->has_xbzrle_cache = true;
 176         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 177         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 178         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 179         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 180         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 181         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 182     }
 183 }
 184
 185 MigrationInfo *qmp_query_migrate(Error **errp)
 186 {
 187     MigrationInfo *info = g_malloc0(sizeof(*info));
 188     MigrationState *s = migrate_get_current();
 189
 190     switch (s->state) {
 191     case MIG_STATE_NONE:
 192         /* no migration has happened ever */
 193         break;
 194     case MIG_STATE_SETUP:
 195         info->has_status = true;
 196         info->status = g_strdup("setup");
 197         info->has_total_time = false;
 198         break;
 199     case MIG_STATE_ACTIVE:
 200     case MIG_STATE_CANCELLING:
 201         info->has_status = true;
 202         info->status = g_strdup("active");
 203         info->has_total_time = true;
 204         info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
 205             - s->total_time;
 206         info->has_expected_downtime = true;
 207         info->expected_downtime = s->expected_downtime;
 208         info->has_setup_time = true;
 209         info->setup_time = s->setup_time;
 210
 211         info->has_ram = true;
 212         info->ram = g_malloc0(sizeof(*info->ram));
 213         info->ram->transferred = ram_bytes_transferred();
 214         info->ram->remaining = ram_bytes_remaining();
 215         info->ram->total = ram_bytes_total();
 216         info->ram->duplicate = dup_mig_pages_transferred();
 217         info->ram->skipped = skipped_mig_pages_transferred();
 218         info->ram->normal = norm_mig_pages_transferred();
 219         info->ram->normal_bytes = norm_mig_bytes_transferred();
 220         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 221         info->ram->mbps = s->mbps;
 222
 223         if (blk_mig_active()) {
 224             info->has_disk = true;
 225             info->disk = g_malloc0(sizeof(*info->disk));
 226             info->disk->transferred = blk_mig_bytes_transferred();
 227             info->disk->remaining = blk_mig_bytes_remaining();
 228             info->disk->total = blk_mig_bytes_total();
 229         }
 230
 231         get_xbzrle_cache_stats(info);
 232         break;
 233     case MIG_STATE_COMPLETED:
 234         get_xbzrle_cache_stats(info);
 235
 236         info->has_status = true;
 237         info->status = g_strdup("completed");
 238         info->has_total_time = true;
 239         info->total_time = s->total_time;
 240         info->has_downtime = true;
 241         info->downtime = s->downtime;
 242         info->has_setup_time = true;
 243         info->setup_time = s->setup_time;
 244
 245         info->has_ram = true;
 246         info->ram = g_malloc0(sizeof(*info->ram));
 247         info->ram->transferred = ram_bytes_transferred();
 248         info->ram->remaining = 0;
 249         info->ram->total = ram_bytes_total();
 250         info->ram->duplicate = dup_mig_pages_transferred();
 251         info->ram->skipped = skipped_mig_pages_transferred();
 252         info->ram->normal = norm_mig_pages_transferred();
 253         info->ram->normal_bytes = norm_mig_bytes_transferred();
 254         info->ram->mbps = s->mbps;
 255         break;
 256     case MIG_STATE_ERROR:
 257         info->has_status = true;
 258         info->status = g_strdup("failed");
 259         break;
 260     case MIG_STATE_CANCELLED:
 261         info->has_status = true;
 262         info->status = g_strdup("cancelled");
 263         break;
 264     }
 265
 266     return info;
 267 }
 268
 269 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 270                                   Error **errp)
 271 {
 272     MigrationState *s = migrate_get_current();
 273     MigrationCapabilityStatusList *cap;
 274
 275     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
 276         error_set(errp, QERR_MIGRATION_ACTIVE);
 277         return;
 278     }
 279
 280     for (cap = params; cap; cap = cap->next) {
 281         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 282     }
 283 }
 284
 285 /* shared migration helpers */
 286
 287 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 288 {
 289     if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
 290         trace_migrate_set_state(new_state);
 291     }
 292 }
 293
 294 static void migrate_fd_cleanup(void *opaque)
 295 {
 296     MigrationState *s = opaque;
 297
 298     qemu_bh_delete(s->cleanup_bh);
 299     s->cleanup_bh = NULL;
 300
 301     if (s->file) {
 302         DPRINTF("closing file\n");
 303         qemu_mutex_unlock_iothread();
 304         qemu_thread_join(&s->thread);
 305         qemu_mutex_lock_iothread();
 306
 307         qemu_fclose(s->file);
 308         s->file = NULL;
 309     }
 310
 311     assert(s->state != MIG_STATE_ACTIVE);
 312
 313     if (s->state != MIG_STATE_COMPLETED) {
 314         qemu_savevm_state_cancel();
 315         if (s->state == MIG_STATE_CANCELLING) {
 316             migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
 317         }
 318     }
 319
 320     notifier_list_notify(&migration_state_notifiers, s);
 321 }
 322
 323 void migrate_fd_error(MigrationState *s)
 324 {
 325     DPRINTF("setting error state\n");
 326     assert(s->file == NULL);
 327     s->state = MIG_STATE_ERROR;
 328     trace_migrate_set_state(MIG_STATE_ERROR);
 329     notifier_list_notify(&migration_state_notifiers, s);
 330 }
 331
 332 static void migrate_fd_cancel(MigrationState *s)
 333 {
 334     int old_state ;
 335     DPRINTF("cancelling migration\n");
 336
 337     do {
 338         old_state = s->state;
 339         if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
 340             break;
 341         }
 342         migrate_set_state(s, old_state, MIG_STATE_CANCELLING);
 343     } while (s->state != MIG_STATE_CANCELLING);
 344 }
 345
 346 void add_migration_state_change_notifier(Notifier *notify)
 347 {
 348     notifier_list_add(&migration_state_notifiers, notify);
 349 }
 350
 351 void remove_migration_state_change_notifier(Notifier *notify)
 352 {
 353     notifier_remove(notify);
 354 }
 355
 356 bool migration_in_setup(MigrationState *s)
 357 {
 358     return s->state == MIG_STATE_SETUP;
 359 }
 360
 361 bool migration_has_finished(MigrationState *s)
 362 {
 363     return s->state == MIG_STATE_COMPLETED;
 364 }
 365
 366 bool migration_has_failed(MigrationState *s)
 367 {
 368     return (s->state == MIG_STATE_CANCELLED ||
 369             s->state == MIG_STATE_ERROR);
 370 }
 371
 372 static MigrationState *migrate_init(const MigrationParams *params)
 373 {
 374     MigrationState *s = migrate_get_current();
 375     int64_t bandwidth_limit = s->bandwidth_limit;
 376     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 377     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 378
 379     memcpy(enabled_capabilities, s->enabled_capabilities,
 380            sizeof(enabled_capabilities));
 381
 382     memset(s, 0, sizeof(*s));
 383     s->params = *params;
 384     memcpy(s->enabled_capabilities, enabled_capabilities,
 385            sizeof(enabled_capabilities));
 386     s->xbzrle_cache_size = xbzrle_cache_size;
 387
 388     s->bandwidth_limit = bandwidth_limit;
 389     s->state = MIG_STATE_SETUP;
 390     trace_migrate_set_state(MIG_STATE_SETUP);
 391
 392     s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 393     return s;
 394 }
 395
 396 static GSList *migration_blockers;
 397
 398 void migrate_add_blocker(Error *reason)
 399 {
 400     migration_blockers = g_slist_prepend(migration_blockers, reason);
 401 }
 402
 403 void migrate_del_blocker(Error *reason)
 404 {
 405     migration_blockers = g_slist_remove(migration_blockers, reason);
 406 }
 407
 408 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 409                  bool has_inc, bool inc, bool has_detach, bool detach,
 410                  Error **errp)
 411 {
 412     Error *local_err = NULL;
 413     MigrationState *s = migrate_get_current();
 414     MigrationParams params;
 415     const char *p;
 416
 417     params.blk = has_blk && blk;
 418     params.shared = has_inc && inc;
 419
 420     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
 421         s->state == MIG_STATE_CANCELLING) {
 422         error_set(errp, QERR_MIGRATION_ACTIVE);
 423         return;
 424     }
 425
 426     if (qemu_savevm_state_blocked(errp)) {
 427         return;
 428     }
 429
 430     if (migration_blockers) {
 431         *errp = error_copy(migration_blockers->data);
 432         return;
 433     }
 434
 435     s = migrate_init(&params);
 436
 437     if (strstart(uri, "tcp:", &p)) {
 438         tcp_start_outgoing_migration(s, p, &local_err);
 439 #ifdef CONFIG_RDMA
 440     } else if (strstart(uri, "x-rdma:", &p)) {
 441         rdma_start_outgoing_migration(s, p, &local_err);
 442 #endif
 443 #if !defined(WIN32)
 444     } else if (strstart(uri, "exec:", &p)) {
 445         exec_start_outgoing_migration(s, p, &local_err);
 446     } else if (strstart(uri, "unix:", &p)) {
 447         unix_start_outgoing_migration(s, p, &local_err);
 448     } else if (strstart(uri, "fd:", &p)) {
 449         fd_start_outgoing_migration(s, p, &local_err);
 450 #endif
 451     } else {
 452         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 453         s->state = MIG_STATE_ERROR;
 454         return;
 455     }
 456
 457     if (local_err) {
 458         migrate_fd_error(s);
 459         error_propagate(errp, local_err);
 460         return;
 461     }
 462 }
 463
 464 void qmp_migrate_cancel(Error **errp)
 465 {
 466     migrate_fd_cancel(migrate_get_current());
 467 }
 468
 469 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 470 {
 471     MigrationState *s = migrate_get_current();
 472
 473     /* Check for truncation */
 474     if (value != (size_t)value) {
 475         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 476                   "exceeding address space");
 477         return;
 478     }
 479
 480     s->xbzrle_cache_size = xbzrle_cache_resize(value);
 481 }
 482
 483 int64_t qmp_query_migrate_cache_size(Error **errp)
 484 {
 485     return migrate_xbzrle_cache_size();
 486 }
 487
 488 void qmp_migrate_set_speed(int64_t value, Error **errp)
 489 {
 490     MigrationState *s;
 491
 492     if (value < 0) {
 493         value = 0;
 494     }
 495     if (value > SIZE_MAX) {
 496         value = SIZE_MAX;
 497     }
 498
 499     s = migrate_get_current();
 500     s->bandwidth_limit = value;
 501     if (s->file) {
 502         qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
 503     }
 504 }
 505
 506 void qmp_migrate_set_downtime(double value, Error **errp)
 507 {
 508     value *= 1e9;
 509     value = MAX(0, MIN(UINT64_MAX, value));
 510     max_downtime = (uint64_t)value;
 511 }
 512
 513 bool migrate_rdma_pin_all(void)
 514 {
 515     MigrationState *s;
 516
 517     s = migrate_get_current();
 518
 519     return s->enabled_capabilities[MIGRATION_CAPABILITY_X_RDMA_PIN_ALL];
 520 }
 521
 522 bool migrate_auto_converge(void)
 523 {
 524     MigrationState *s;
 525
 526     s = migrate_get_current();
 527
 528     return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
 529 }
 530
 531 bool migrate_zero_blocks(void)
 532 {
 533     MigrationState *s;
 534
 535     s = migrate_get_current();
 536
 537     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 538 }
 539
 540 int migrate_use_xbzrle(void)
 541 {
 542     MigrationState *s;
 543
 544     s = migrate_get_current();
 545
 546     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 547 }
 548
 549 int64_t migrate_xbzrle_cache_size(void)
 550 {
 551     MigrationState *s;
 552
 553     s = migrate_get_current();
 554
 555     return s->xbzrle_cache_size;
 556 }
 557
 558 /* migration thread support */
 559
 560 static void *migration_thread(void *opaque)
 561 {
 562     MigrationState *s = opaque;
 563     int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 564     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 565     int64_t initial_bytes = 0;
 566     int64_t max_size = 0;
 567     int64_t start_time = initial_time;
 568     bool old_vm_running = false;
 569
 570     DPRINTF("beginning savevm\n");
 571     qemu_savevm_state_begin(s->file, &s->params);
 572
 573     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
 574     migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
 575
 576     DPRINTF("setup complete\n");
 577
 578     while (s->state == MIG_STATE_ACTIVE) {
 579         int64_t current_time;
 580         uint64_t pending_size;
 581
 582         if (!qemu_file_rate_limit(s->file)) {
 583             DPRINTF("iterate\n");
 584             pending_size = qemu_savevm_state_pending(s->file, max_size);
 585             DPRINTF("pending size %" PRIu64 " max %" PRIu64 "\n",
 586                     pending_size, max_size);
 587             if (pending_size && pending_size >= max_size) {
 588                 qemu_savevm_state_iterate(s->file);
 589             } else {
 590                 int ret;
 591
 592                 DPRINTF("done iterating\n");
 593                 qemu_mutex_lock_iothread();
 594                 start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 595                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 596                 old_vm_running = runstate_is_running();
 597
 598                 ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 599                 if (ret >= 0) {
 600                     qemu_file_set_rate_limit(s->file, INT64_MAX);
 601                     qemu_savevm_state_complete(s->file);
 602                 }
 603                 qemu_mutex_unlock_iothread();
 604
 605                 if (ret < 0) {
 606                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 607                     break;
 608                 }
 609
 610                 if (!qemu_file_get_error(s->file)) {
 611                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
 612                     break;
 613                 }
 614             }
 615         }
 616
 617         if (qemu_file_get_error(s->file)) {
 618             migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 619             break;
 620         }
 621         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 622         if (current_time >= initial_time + BUFFER_DELAY) {
 623             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
 624             uint64_t time_spent = current_time - initial_time;
 625             double bandwidth = transferred_bytes / time_spent;
 626             max_size = bandwidth * migrate_max_downtime() / 1000000;
 627
 628             s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
 629                     ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
 630
 631             DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64
 632                     " bandwidth %g max_size %" PRId64 "\n",
 633                     transferred_bytes, time_spent, bandwidth, max_size);
 634             /* if we haven't sent anything, we don't want to recalculate
 635                10000 is a small enough number for our purposes */
 636             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 637                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 638             }
 639
 640             qemu_file_reset_rate_limit(s->file);
 641             initial_time = current_time;
 642             initial_bytes = qemu_ftell(s->file);
 643         }
 644         if (qemu_file_rate_limit(s->file)) {
 645             /* usleep expects microseconds */
 646             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 647         }
 648     }
 649
 650     qemu_mutex_lock_iothread();
 651     if (s->state == MIG_STATE_COMPLETED) {
 652         int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 653         s->total_time = end_time - s->total_time;
 654         s->downtime = end_time - start_time;
 655         runstate_set(RUN_STATE_POSTMIGRATE);
 656     } else {
 657         if (old_vm_running) {
 658             vm_start();
 659         }
 660     }
 661     qemu_bh_schedule(s->cleanup_bh);
 662     qemu_mutex_unlock_iothread();
 663
 664     return NULL;
 665 }
 666
 667 void migrate_fd_connect(MigrationState *s)
 668 {
 669     s->state = MIG_STATE_SETUP;
 670     trace_migrate_set_state(MIG_STATE_SETUP);
 671
 672     /* This is a best 1st approximation. ns to ms */
 673     s->expected_downtime = max_downtime/1000000;
 674     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 675
 676     qemu_file_set_rate_limit(s->file,
 677                              s->bandwidth_limit / XFER_LIMIT_RATIO);
 678
 679     /* Notify before starting migration thread */
 680     notifier_list_notify(&migration_state_notifiers, s);
 681
 682     qemu_thread_create(&s->thread, migration_thread, s,
 683                        QEMU_THREAD_JOINABLE);
 684 }