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 "migration/migration.h"
  18 #include "monitor/monitor.h"
  19 #include "migration/qemu-file.h"
  20 #include "sysemu/sysemu.h"
  21 #include "block/block.h"
  22 #include "qemu/sockets.h"
  23 #include "migration/block.h"
  24 #include "qemu/thread.h"
  25 #include "qmp-commands.h"
  26 #include "trace.h"
  27
  28 //#define DEBUG_MIGRATION
  29
  30 #ifdef DEBUG_MIGRATION
  31 #define DPRINTF(fmt, ...) \
  32     do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)
  33 #else
  34 #define DPRINTF(fmt, ...) \
  35     do { } while (0)
  36 #endif
  37
  38 enum {
  39     MIG_STATE_ERROR,
  40     MIG_STATE_SETUP,
  41     MIG_STATE_CANCELLED,
  42     MIG_STATE_ACTIVE,
  43     MIG_STATE_COMPLETED,
  44 };
  45
  46 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
  47
  48 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
  49  * data. */
  50 #define BUFFER_DELAY     100
  51 #define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
  52
  53 /* Migration XBZRLE default cache size */
  54 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
  55
  56 static NotifierList migration_state_notifiers =
  57     NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
  58
  59 /* When we add fault tolerance, we could have several
  60    migrations at once.  For now we don't need to add
  61    dynamic creation of migration */
  62
  63 MigrationState *migrate_get_current(void)
  64 {
  65     static MigrationState current_migration = {
  66         .state = MIG_STATE_SETUP,
  67         .bandwidth_limit = MAX_THROTTLE,
  68         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
  69     };
  70
  71     return &current_migration;
  72 }
  73
  74 void qemu_start_incoming_migration(const char *uri, Error **errp)
  75 {
  76     const char *p;
  77
  78     if (strstart(uri, "tcp:", &p))
  79         tcp_start_incoming_migration(p, errp);
  80 #if !defined(WIN32)
  81     else if (strstart(uri, "exec:", &p))
  82         exec_start_incoming_migration(p, errp);
  83     else if (strstart(uri, "unix:", &p))
  84         unix_start_incoming_migration(p, errp);
  85     else if (strstart(uri, "fd:", &p))
  86         fd_start_incoming_migration(p, errp);
  87 #endif
  88     else {
  89         error_setg(errp, "unknown migration protocol: %s", uri);
  90     }
  91 }
  92
  93 static void process_incoming_migration_co(void *opaque)
  94 {
  95     QEMUFile *f = opaque;
  96     int ret;
  97
  98     ret = qemu_loadvm_state(f);
  99     qemu_fclose(f);
 100     if (ret < 0) {
 101         fprintf(stderr, "load of migration failed\n");
 102         exit(0);
 103     }
 104     qemu_announce_self();
 105     DPRINTF("successfully loaded vm state\n");
 106
 107     bdrv_clear_incoming_migration_all();
 108     /* Make sure all file formats flush their mutable metadata */
 109     bdrv_invalidate_cache_all();
 110
 111     if (autostart) {
 112         vm_start();
 113     } else {
 114         runstate_set(RUN_STATE_PAUSED);
 115     }
 116 }
 117
 118 void process_incoming_migration(QEMUFile *f)
 119 {
 120     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 121     int fd = qemu_get_fd(f);
 122
 123     assert(fd != -1);
 124     socket_set_nonblock(fd);
 125     qemu_coroutine_enter(co, f);
 126 }
 127
 128 /* amount of nanoseconds we are willing to wait for migration to be down.
 129  * the choice of nanoseconds is because it is the maximum resolution that
 130  * get_clock() can achieve. It is an internal measure. All user-visible
 131  * units must be in seconds */
 132 static uint64_t max_downtime = 30000000;
 133
 134 uint64_t migrate_max_downtime(void)
 135 {
 136     return max_downtime;
 137 }
 138
 139 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 140 {
 141     MigrationCapabilityStatusList *head = NULL;
 142     MigrationCapabilityStatusList *caps;
 143     MigrationState *s = migrate_get_current();
 144     int i;
 145
 146     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 147         if (head == NULL) {
 148             head = g_malloc0(sizeof(*caps));
 149             caps = head;
 150         } else {
 151             caps->next = g_malloc0(sizeof(*caps));
 152             caps = caps->next;
 153         }
 154         caps->value =
 155             g_malloc(sizeof(*caps->value));
 156         caps->value->capability = i;
 157         caps->value->state = s->enabled_capabilities[i];
 158     }
 159
 160     return head;
 161 }
 162
 163 static void get_xbzrle_cache_stats(MigrationInfo *info)
 164 {
 165     if (migrate_use_xbzrle()) {
 166         info->has_xbzrle_cache = true;
 167         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 168         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 169         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 170         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 171         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 172         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 173     }
 174 }
 175
 176 MigrationInfo *qmp_query_migrate(Error **errp)
 177 {
 178     MigrationInfo *info = g_malloc0(sizeof(*info));
 179     MigrationState *s = migrate_get_current();
 180
 181     switch (s->state) {
 182     case MIG_STATE_SETUP:
 183         /* no migration has happened ever */
 184         break;
 185     case MIG_STATE_ACTIVE:
 186         info->has_status = true;
 187         info->status = g_strdup("active");
 188         info->has_total_time = true;
 189         info->total_time = qemu_get_clock_ms(rt_clock)
 190             - s->total_time;
 191         info->has_expected_downtime = true;
 192         info->expected_downtime = s->expected_downtime;
 193
 194         info->has_ram = true;
 195         info->ram = g_malloc0(sizeof(*info->ram));
 196         info->ram->transferred = ram_bytes_transferred();
 197         info->ram->remaining = ram_bytes_remaining();
 198         info->ram->total = ram_bytes_total();
 199         info->ram->duplicate = dup_mig_pages_transferred();
 200         info->ram->normal = norm_mig_pages_transferred();
 201         info->ram->normal_bytes = norm_mig_bytes_transferred();
 202         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 203
 204
 205         if (blk_mig_active()) {
 206             info->has_disk = true;
 207             info->disk = g_malloc0(sizeof(*info->disk));
 208             info->disk->transferred = blk_mig_bytes_transferred();
 209             info->disk->remaining = blk_mig_bytes_remaining();
 210             info->disk->total = blk_mig_bytes_total();
 211         }
 212
 213         get_xbzrle_cache_stats(info);
 214         break;
 215     case MIG_STATE_COMPLETED:
 216         get_xbzrle_cache_stats(info);
 217
 218         info->has_status = true;
 219         info->status = g_strdup("completed");
 220         info->total_time = s->total_time;
 221         info->has_downtime = true;
 222         info->downtime = s->downtime;
 223
 224         info->has_ram = true;
 225         info->ram = g_malloc0(sizeof(*info->ram));
 226         info->ram->transferred = ram_bytes_transferred();
 227         info->ram->remaining = 0;
 228         info->ram->total = ram_bytes_total();
 229         info->ram->duplicate = dup_mig_pages_transferred();
 230         info->ram->normal = norm_mig_pages_transferred();
 231         info->ram->normal_bytes = norm_mig_bytes_transferred();
 232         break;
 233     case MIG_STATE_ERROR:
 234         info->has_status = true;
 235         info->status = g_strdup("failed");
 236         break;
 237     case MIG_STATE_CANCELLED:
 238         info->has_status = true;
 239         info->status = g_strdup("cancelled");
 240         break;
 241     }
 242
 243     return info;
 244 }
 245
 246 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 247                                   Error **errp)
 248 {
 249     MigrationState *s = migrate_get_current();
 250     MigrationCapabilityStatusList *cap;
 251
 252     if (s->state == MIG_STATE_ACTIVE) {
 253         error_set(errp, QERR_MIGRATION_ACTIVE);
 254         return;
 255     }
 256
 257     for (cap = params; cap; cap = cap->next) {
 258         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 259     }
 260 }
 261
 262 /* shared migration helpers */
 263
 264 static void migrate_fd_cleanup(void *opaque)
 265 {
 266     MigrationState *s = opaque;
 267
 268     qemu_bh_delete(s->cleanup_bh);
 269     s->cleanup_bh = NULL;
 270
 271     if (s->file) {
 272         DPRINTF("closing file\n");
 273         qemu_fclose(s->file);
 274         s->file = NULL;
 275     }
 276
 277     assert(s->migration_file == NULL);
 278     assert(s->state != MIG_STATE_ACTIVE);
 279
 280     if (s->state != MIG_STATE_COMPLETED) {
 281         qemu_savevm_state_cancel();
 282     }
 283
 284     notifier_list_notify(&migration_state_notifiers, s);
 285 }
 286
 287 static void migrate_finish_set_state(MigrationState *s, int new_state)
 288 {
 289     if (__sync_val_compare_and_swap(&s->state, MIG_STATE_ACTIVE,
 290                                     new_state) == new_state) {
 291         trace_migrate_set_state(new_state);
 292     }
 293 }
 294
 295 void migrate_fd_error(MigrationState *s)
 296 {
 297     DPRINTF("setting error state\n");
 298     assert(s->file == NULL);
 299     s->state = MIG_STATE_ERROR;
 300     trace_migrate_set_state(MIG_STATE_ERROR);
 301     notifier_list_notify(&migration_state_notifiers, s);
 302 }
 303
 304 static ssize_t migrate_fd_put_buffer(MigrationState *s, const void *data,
 305                                      size_t size)
 306 {
 307     ssize_t ret;
 308
 309     if (s->state != MIG_STATE_ACTIVE) {
 310         return -EIO;
 311     }
 312
 313     do {
 314         ret = s->write(s, data, size);
 315     } while (ret == -1 && ((s->get_error(s)) == EINTR));
 316
 317     if (ret == -1)
 318         ret = -(s->get_error(s));
 319
 320     return ret;
 321 }
 322
 323 static void migrate_fd_cancel(MigrationState *s)
 324 {
 325     DPRINTF("cancelling migration\n");
 326
 327     migrate_finish_set_state(s, MIG_STATE_CANCELLED);
 328 }
 329
 330 int migrate_fd_close(MigrationState *s)
 331 {
 332     int rc = 0;
 333     if (s->migration_file != NULL) {
 334         rc = qemu_fclose(s->migration_file);
 335         s->migration_file = NULL;
 336         s->fd = -1;
 337     }
 338     return rc;
 339 }
 340
 341 void add_migration_state_change_notifier(Notifier *notify)
 342 {
 343     notifier_list_add(&migration_state_notifiers, notify);
 344 }
 345
 346 void remove_migration_state_change_notifier(Notifier *notify)
 347 {
 348     notifier_remove(notify);
 349 }
 350
 351 bool migration_is_active(MigrationState *s)
 352 {
 353     return s->state == MIG_STATE_ACTIVE;
 354 }
 355
 356 bool migration_has_finished(MigrationState *s)
 357 {
 358     return s->state == MIG_STATE_COMPLETED;
 359 }
 360
 361 bool migration_has_failed(MigrationState *s)
 362 {
 363     return (s->state == MIG_STATE_CANCELLED ||
 364             s->state == MIG_STATE_ERROR);
 365 }
 366
 367 static MigrationState *migrate_init(const MigrationParams *params)
 368 {
 369     MigrationState *s = migrate_get_current();
 370     int64_t bandwidth_limit = s->bandwidth_limit;
 371     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 372     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 373
 374     memcpy(enabled_capabilities, s->enabled_capabilities,
 375            sizeof(enabled_capabilities));
 376
 377     memset(s, 0, sizeof(*s));
 378     s->bandwidth_limit = bandwidth_limit;
 379     s->params = *params;
 380     memcpy(s->enabled_capabilities, enabled_capabilities,
 381            sizeof(enabled_capabilities));
 382     s->xbzrle_cache_size = xbzrle_cache_size;
 383
 384     s->bandwidth_limit = bandwidth_limit;
 385     s->state = MIG_STATE_SETUP;
 386     trace_migrate_set_state(MIG_STATE_SETUP);
 387
 388     s->total_time = qemu_get_clock_ms(rt_clock);
 389     return s;
 390 }
 391
 392 static GSList *migration_blockers;
 393
 394 void migrate_add_blocker(Error *reason)
 395 {
 396     migration_blockers = g_slist_prepend(migration_blockers, reason);
 397 }
 398
 399 void migrate_del_blocker(Error *reason)
 400 {
 401     migration_blockers = g_slist_remove(migration_blockers, reason);
 402 }
 403
 404 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 405                  bool has_inc, bool inc, bool has_detach, bool detach,
 406                  Error **errp)
 407 {
 408     Error *local_err = NULL;
 409     MigrationState *s = migrate_get_current();
 410     MigrationParams params;
 411     const char *p;
 412
 413     params.blk = blk;
 414     params.shared = inc;
 415
 416     if (s->state == MIG_STATE_ACTIVE) {
 417         error_set(errp, QERR_MIGRATION_ACTIVE);
 418         return;
 419     }
 420
 421     if (qemu_savevm_state_blocked(errp)) {
 422         return;
 423     }
 424
 425     if (migration_blockers) {
 426         *errp = error_copy(migration_blockers->data);
 427         return;
 428     }
 429
 430     s = migrate_init(&params);
 431
 432     if (strstart(uri, "tcp:", &p)) {
 433         tcp_start_outgoing_migration(s, p, &local_err);
 434 #if !defined(WIN32)
 435     } else if (strstart(uri, "exec:", &p)) {
 436         exec_start_outgoing_migration(s, p, &local_err);
 437     } else if (strstart(uri, "unix:", &p)) {
 438         unix_start_outgoing_migration(s, p, &local_err);
 439     } else if (strstart(uri, "fd:", &p)) {
 440         fd_start_outgoing_migration(s, p, &local_err);
 441 #endif
 442     } else {
 443         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 444         return;
 445     }
 446
 447     if (local_err) {
 448         migrate_fd_error(s);
 449         error_propagate(errp, local_err);
 450         return;
 451     }
 452 }
 453
 454 void qmp_migrate_cancel(Error **errp)
 455 {
 456     migrate_fd_cancel(migrate_get_current());
 457 }
 458
 459 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 460 {
 461     MigrationState *s = migrate_get_current();
 462
 463     /* Check for truncation */
 464     if (value != (size_t)value) {
 465         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 466                   "exceeding address space");
 467         return;
 468     }
 469
 470     s->xbzrle_cache_size = xbzrle_cache_resize(value);
 471 }
 472
 473 int64_t qmp_query_migrate_cache_size(Error **errp)
 474 {
 475     return migrate_xbzrle_cache_size();
 476 }
 477
 478 void qmp_migrate_set_speed(int64_t value, Error **errp)
 479 {
 480     MigrationState *s;
 481
 482     if (value < 0) {
 483         value = 0;
 484     }
 485
 486     s = migrate_get_current();
 487     s->bandwidth_limit = value;
 488     qemu_file_set_rate_limit(s->file, s->bandwidth_limit);
 489 }
 490
 491 void qmp_migrate_set_downtime(double value, Error **errp)
 492 {
 493     value *= 1e9;
 494     value = MAX(0, MIN(UINT64_MAX, value));
 495     max_downtime = (uint64_t)value;
 496 }
 497
 498 int migrate_use_xbzrle(void)
 499 {
 500     MigrationState *s;
 501
 502     s = migrate_get_current();
 503
 504     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 505 }
 506
 507 int64_t migrate_xbzrle_cache_size(void)
 508 {
 509     MigrationState *s;
 510
 511     s = migrate_get_current();
 512
 513     return s->xbzrle_cache_size;
 514 }
 515
 516 /* migration thread support */
 517
 518 static int migration_put_buffer(void *opaque, const uint8_t *buf,
 519                                int64_t pos, int size)
 520 {
 521     MigrationState *s = opaque;
 522     ssize_t ret;
 523     size_t sent;
 524
 525     DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
 526
 527     if (size <= 0) {
 528         return size;
 529     }
 530
 531     sent = 0;
 532     while (size) {
 533         ret = migrate_fd_put_buffer(s, buf, size);
 534         if (ret <= 0) {
 535             DPRINTF("error flushing data, %zd\n", ret);
 536             return ret;
 537         } else {
 538             DPRINTF("flushed %zd byte(s)\n", ret);
 539             sent += ret;
 540             buf += ret;
 541             size -= ret;
 542             s->bytes_xfer += ret;
 543         }
 544     }
 545
 546     return sent;
 547 }
 548
 549 static int migration_close(void *opaque)
 550 {
 551     MigrationState *s = opaque;
 552
 553     DPRINTF("closing\n");
 554
 555     qemu_mutex_unlock_iothread();
 556     qemu_thread_join(&s->thread);
 557     qemu_mutex_lock_iothread();
 558     assert(s->state != MIG_STATE_ACTIVE);
 559
 560     return migrate_fd_close(s);
 561 }
 562
 563 static int migration_get_fd(void *opaque)
 564 {
 565     MigrationState *s = opaque;
 566
 567     return s->fd;
 568 }
 569
 570 /*
 571  * The meaning of the return values is:
 572  *   0: We can continue sending
 573  *   1: Time to stop
 574  *   negative: There has been an error
 575  */
 576 static int migration_rate_limit(void *opaque)
 577 {
 578     MigrationState *s = opaque;
 579     int ret;
 580
 581     ret = qemu_file_get_error(s->file);
 582     if (ret) {
 583         return ret;
 584     }
 585
 586     if (s->bytes_xfer >= s->xfer_limit) {
 587         return 1;
 588     }
 589
 590     return 0;
 591 }
 592
 593 static int64_t migration_set_rate_limit(void *opaque, int64_t new_rate)
 594 {
 595     MigrationState *s = opaque;
 596     if (qemu_file_get_error(s->file)) {
 597         goto out;
 598     }
 599     if (new_rate > SIZE_MAX) {
 600         new_rate = SIZE_MAX;
 601     }
 602
 603     s->xfer_limit = new_rate / XFER_LIMIT_RATIO;
 604
 605 out:
 606     return s->xfer_limit;
 607 }
 608
 609 static int64_t migration_get_rate_limit(void *opaque)
 610 {
 611     MigrationState *s = opaque;
 612
 613     return s->xfer_limit;
 614 }
 615
 616 static void *migration_thread(void *opaque)
 617 {
 618     MigrationState *s = opaque;
 619     int64_t initial_time = qemu_get_clock_ms(rt_clock);
 620     int64_t sleep_time = 0;
 621     int64_t max_size = 0;
 622     int64_t start_time = initial_time;
 623     bool old_vm_running = false;
 624
 625     DPRINTF("beginning savevm\n");
 626     qemu_savevm_state_begin(s->file, &s->params);
 627
 628     while (s->state == MIG_STATE_ACTIVE) {
 629         int64_t current_time;
 630         uint64_t pending_size;
 631
 632         if (!qemu_file_rate_limit(s->file)) {
 633             DPRINTF("iterate\n");
 634             pending_size = qemu_savevm_state_pending(s->file, max_size);
 635             DPRINTF("pending size %lu max %lu\n", pending_size, max_size);
 636             if (pending_size && pending_size >= max_size) {
 637                 qemu_savevm_state_iterate(s->file);
 638             } else {
 639                 DPRINTF("done iterating\n");
 640                 qemu_mutex_lock_iothread();
 641                 start_time = qemu_get_clock_ms(rt_clock);
 642                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 643                 old_vm_running = runstate_is_running();
 644                 vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 645                 s->xfer_limit = INT_MAX;
 646                 qemu_savevm_state_complete(s->file);
 647                 qemu_mutex_unlock_iothread();
 648                 if (!qemu_file_get_error(s->file)) {
 649                     migrate_finish_set_state(s, MIG_STATE_COMPLETED);
 650                     break;
 651                 }
 652             }
 653         }
 654
 655         if (qemu_file_get_error(s->file)) {
 656             migrate_finish_set_state(s, MIG_STATE_ERROR);
 657             break;
 658         }
 659         current_time = qemu_get_clock_ms(rt_clock);
 660         if (current_time >= initial_time + BUFFER_DELAY) {
 661             uint64_t transferred_bytes = s->bytes_xfer;
 662             uint64_t time_spent = current_time - initial_time - sleep_time;
 663             double bandwidth = transferred_bytes / time_spent;
 664             max_size = bandwidth * migrate_max_downtime() / 1000000;
 665
 666             DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64
 667                     " bandwidth %g max_size %" PRId64 "\n",
 668                     transferred_bytes, time_spent, bandwidth, max_size);
 669             /* if we haven't sent anything, we don't want to recalculate
 670                10000 is a small enough number for our purposes */
 671             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 672                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 673             }
 674
 675             s->bytes_xfer = 0;
 676             sleep_time = 0;
 677             initial_time = current_time;
 678         }
 679         if (qemu_file_rate_limit(s->file)) {
 680             /* usleep expects microseconds */
 681             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 682             sleep_time += qemu_get_clock_ms(rt_clock) - current_time;
 683         }
 684     }
 685
 686     qemu_mutex_lock_iothread();
 687     if (s->state == MIG_STATE_COMPLETED) {
 688         int64_t end_time = qemu_get_clock_ms(rt_clock);
 689         s->total_time = end_time - s->total_time;
 690         s->downtime = end_time - start_time;
 691         runstate_set(RUN_STATE_POSTMIGRATE);
 692     } else {
 693         if (old_vm_running) {
 694             vm_start();
 695         }
 696     }
 697     qemu_bh_schedule(s->cleanup_bh);
 698     qemu_mutex_unlock_iothread();
 699
 700     return NULL;
 701 }
 702
 703 static const QEMUFileOps migration_file_ops = {
 704     .get_fd =         migration_get_fd,
 705     .put_buffer =     migration_put_buffer,
 706     .close =          migration_close,
 707     .rate_limit =     migration_rate_limit,
 708     .get_rate_limit = migration_get_rate_limit,
 709     .set_rate_limit = migration_set_rate_limit,
 710 };
 711
 712 void migrate_fd_connect(MigrationState *s)
 713 {
 714     s->state = MIG_STATE_ACTIVE;
 715     trace_migrate_set_state(MIG_STATE_ACTIVE);
 716
 717     s->bytes_xfer = 0;
 718     /* This is a best 1st approximation. ns to ms */
 719     s->expected_downtime = max_downtime/1000000;
 720
 721     s->xfer_limit = s->bandwidth_limit / XFER_LIMIT_RATIO;
 722
 723     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 724     s->fd = qemu_get_fd(s->migration_file);
 725     s->file = qemu_fopen_ops(s, &migration_file_ops);
 726
 727     qemu_thread_create(&s->thread, migration_thread, s,
 728                        QEMU_THREAD_JOINABLE);
 729     notifier_list_notify(&migration_state_notifiers, s);
 730 }