xref: /openbmc/qemu/migration/migration.c (revision 21f5826a)
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         error_report("load of migration failed: %s", strerror(-ret));
102         exit(EXIT_FAILURE);
103     }
104     qemu_announce_self();
105 
106     /* Make sure all file formats flush their mutable metadata */
107     bdrv_invalidate_cache_all(&local_err);
108     if (local_err) {
109         qerror_report_err(local_err);
110         error_free(local_err);
111         exit(EXIT_FAILURE);
112     }
113 
114     if (autostart) {
115         vm_start();
116     } else {
117         runstate_set(RUN_STATE_PAUSED);
118     }
119 }
120 
121 void process_incoming_migration(QEMUFile *f)
122 {
123     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
124     int fd = qemu_get_fd(f);
125 
126     assert(fd != -1);
127     qemu_set_nonblock(fd);
128     qemu_coroutine_enter(co, f);
129 }
130 
131 /* amount of nanoseconds we are willing to wait for migration to be down.
132  * the choice of nanoseconds is because it is the maximum resolution that
133  * get_clock() can achieve. It is an internal measure. All user-visible
134  * units must be in seconds */
135 static uint64_t max_downtime = 300000000;
136 
137 uint64_t migrate_max_downtime(void)
138 {
139     return max_downtime;
140 }
141 
142 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
143 {
144     MigrationCapabilityStatusList *head = NULL;
145     MigrationCapabilityStatusList *caps;
146     MigrationState *s = migrate_get_current();
147     int i;
148 
149     caps = NULL; /* silence compiler warning */
150     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
151         if (head == NULL) {
152             head = g_malloc0(sizeof(*caps));
153             caps = head;
154         } else {
155             caps->next = g_malloc0(sizeof(*caps));
156             caps = caps->next;
157         }
158         caps->value =
159             g_malloc(sizeof(*caps->value));
160         caps->value->capability = i;
161         caps->value->state = s->enabled_capabilities[i];
162     }
163 
164     return head;
165 }
166 
167 static void get_xbzrle_cache_stats(MigrationInfo *info)
168 {
169     if (migrate_use_xbzrle()) {
170         info->has_xbzrle_cache = true;
171         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
172         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
173         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
174         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
175         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
176         info->xbzrle_cache->cache_miss_rate = xbzrle_mig_cache_miss_rate();
177         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
178     }
179 }
180 
181 MigrationInfo *qmp_query_migrate(Error **errp)
182 {
183     MigrationInfo *info = g_malloc0(sizeof(*info));
184     MigrationState *s = migrate_get_current();
185 
186     switch (s->state) {
187     case MIG_STATE_NONE:
188         /* no migration has happened ever */
189         break;
190     case MIG_STATE_SETUP:
191         info->has_status = true;
192         info->status = g_strdup("setup");
193         info->has_total_time = false;
194         break;
195     case MIG_STATE_ACTIVE:
196     case MIG_STATE_CANCELLING:
197         info->has_status = true;
198         info->status = g_strdup("active");
199         info->has_total_time = true;
200         info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
201             - s->total_time;
202         info->has_expected_downtime = true;
203         info->expected_downtime = s->expected_downtime;
204         info->has_setup_time = true;
205         info->setup_time = s->setup_time;
206 
207         info->has_ram = true;
208         info->ram = g_malloc0(sizeof(*info->ram));
209         info->ram->transferred = ram_bytes_transferred();
210         info->ram->remaining = ram_bytes_remaining();
211         info->ram->total = ram_bytes_total();
212         info->ram->duplicate = dup_mig_pages_transferred();
213         info->ram->skipped = skipped_mig_pages_transferred();
214         info->ram->normal = norm_mig_pages_transferred();
215         info->ram->normal_bytes = norm_mig_bytes_transferred();
216         info->ram->dirty_pages_rate = s->dirty_pages_rate;
217         info->ram->mbps = s->mbps;
218         info->ram->dirty_sync_count = s->dirty_sync_count;
219 
220         if (blk_mig_active()) {
221             info->has_disk = true;
222             info->disk = g_malloc0(sizeof(*info->disk));
223             info->disk->transferred = blk_mig_bytes_transferred();
224             info->disk->remaining = blk_mig_bytes_remaining();
225             info->disk->total = blk_mig_bytes_total();
226         }
227 
228         get_xbzrle_cache_stats(info);
229         break;
230     case MIG_STATE_COMPLETED:
231         get_xbzrle_cache_stats(info);
232 
233         info->has_status = true;
234         info->status = g_strdup("completed");
235         info->has_total_time = true;
236         info->total_time = s->total_time;
237         info->has_downtime = true;
238         info->downtime = s->downtime;
239         info->has_setup_time = true;
240         info->setup_time = s->setup_time;
241 
242         info->has_ram = true;
243         info->ram = g_malloc0(sizeof(*info->ram));
244         info->ram->transferred = ram_bytes_transferred();
245         info->ram->remaining = 0;
246         info->ram->total = ram_bytes_total();
247         info->ram->duplicate = dup_mig_pages_transferred();
248         info->ram->skipped = skipped_mig_pages_transferred();
249         info->ram->normal = norm_mig_pages_transferred();
250         info->ram->normal_bytes = norm_mig_bytes_transferred();
251         info->ram->mbps = s->mbps;
252         info->ram->dirty_sync_count = s->dirty_sync_count;
253         break;
254     case MIG_STATE_ERROR:
255         info->has_status = true;
256         info->status = g_strdup("failed");
257         break;
258     case MIG_STATE_CANCELLED:
259         info->has_status = true;
260         info->status = g_strdup("cancelled");
261         break;
262     }
263 
264     return info;
265 }
266 
267 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
268                                   Error **errp)
269 {
270     MigrationState *s = migrate_get_current();
271     MigrationCapabilityStatusList *cap;
272 
273     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
274         error_set(errp, QERR_MIGRATION_ACTIVE);
275         return;
276     }
277 
278     for (cap = params; cap; cap = cap->next) {
279         s->enabled_capabilities[cap->value->capability] = cap->value->state;
280     }
281 }
282 
283 /* shared migration helpers */
284 
285 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
286 {
287     if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
288         trace_migrate_set_state(new_state);
289     }
290 }
291 
292 static void migrate_fd_cleanup(void *opaque)
293 {
294     MigrationState *s = opaque;
295 
296     qemu_bh_delete(s->cleanup_bh);
297     s->cleanup_bh = NULL;
298 
299     if (s->file) {
300         trace_migrate_fd_cleanup();
301         qemu_mutex_unlock_iothread();
302         qemu_thread_join(&s->thread);
303         qemu_mutex_lock_iothread();
304 
305         qemu_fclose(s->file);
306         s->file = NULL;
307     }
308 
309     assert(s->state != MIG_STATE_ACTIVE);
310 
311     if (s->state != MIG_STATE_COMPLETED) {
312         qemu_savevm_state_cancel();
313         if (s->state == MIG_STATE_CANCELLING) {
314             migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
315         }
316     }
317 
318     notifier_list_notify(&migration_state_notifiers, s);
319 }
320 
321 void migrate_fd_error(MigrationState *s)
322 {
323     trace_migrate_fd_error();
324     assert(s->file == NULL);
325     s->state = MIG_STATE_ERROR;
326     trace_migrate_set_state(MIG_STATE_ERROR);
327     notifier_list_notify(&migration_state_notifiers, s);
328 }
329 
330 static void migrate_fd_cancel(MigrationState *s)
331 {
332     int old_state ;
333     QEMUFile *f = migrate_get_current()->file;
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      * If we're unlucky the migration code might be stuck somewhere in a
346      * send/write while the network has failed and is waiting to timeout;
347      * if we've got shutdown(2) available then we can force it to quit.
348      * The outgoing qemu file gets closed in migrate_fd_cleanup that is
349      * called in a bh, so there is no race against this cancel.
350      */
351     if (s->state == MIG_STATE_CANCELLING && f) {
352         qemu_file_shutdown(f);
353     }
354 }
355 
356 void add_migration_state_change_notifier(Notifier *notify)
357 {
358     notifier_list_add(&migration_state_notifiers, notify);
359 }
360 
361 void remove_migration_state_change_notifier(Notifier *notify)
362 {
363     notifier_remove(notify);
364 }
365 
366 bool migration_in_setup(MigrationState *s)
367 {
368     return s->state == MIG_STATE_SETUP;
369 }
370 
371 bool migration_has_finished(MigrationState *s)
372 {
373     return s->state == MIG_STATE_COMPLETED;
374 }
375 
376 bool migration_has_failed(MigrationState *s)
377 {
378     return (s->state == MIG_STATE_CANCELLED ||
379             s->state == MIG_STATE_ERROR);
380 }
381 
382 static MigrationState *migrate_init(const MigrationParams *params)
383 {
384     MigrationState *s = migrate_get_current();
385     int64_t bandwidth_limit = s->bandwidth_limit;
386     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
387     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
388 
389     memcpy(enabled_capabilities, s->enabled_capabilities,
390            sizeof(enabled_capabilities));
391 
392     memset(s, 0, sizeof(*s));
393     s->params = *params;
394     memcpy(s->enabled_capabilities, enabled_capabilities,
395            sizeof(enabled_capabilities));
396     s->xbzrle_cache_size = xbzrle_cache_size;
397 
398     s->bandwidth_limit = bandwidth_limit;
399     s->state = MIG_STATE_SETUP;
400     trace_migrate_set_state(MIG_STATE_SETUP);
401 
402     s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
403     return s;
404 }
405 
406 static GSList *migration_blockers;
407 
408 void migrate_add_blocker(Error *reason)
409 {
410     migration_blockers = g_slist_prepend(migration_blockers, reason);
411 }
412 
413 void migrate_del_blocker(Error *reason)
414 {
415     migration_blockers = g_slist_remove(migration_blockers, reason);
416 }
417 
418 void qmp_migrate(const char *uri, bool has_blk, bool blk,
419                  bool has_inc, bool inc, bool has_detach, bool detach,
420                  Error **errp)
421 {
422     Error *local_err = NULL;
423     MigrationState *s = migrate_get_current();
424     MigrationParams params;
425     const char *p;
426 
427     params.blk = has_blk && blk;
428     params.shared = has_inc && inc;
429 
430     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
431         s->state == MIG_STATE_CANCELLING) {
432         error_set(errp, QERR_MIGRATION_ACTIVE);
433         return;
434     }
435 
436     if (runstate_check(RUN_STATE_INMIGRATE)) {
437         error_setg(errp, "Guest is waiting for an incoming migration");
438         return;
439     }
440 
441     if (qemu_savevm_state_blocked(errp)) {
442         return;
443     }
444 
445     if (migration_blockers) {
446         *errp = error_copy(migration_blockers->data);
447         return;
448     }
449 
450     s = migrate_init(&params);
451 
452     if (strstart(uri, "tcp:", &p)) {
453         tcp_start_outgoing_migration(s, p, &local_err);
454 #ifdef CONFIG_RDMA
455     } else if (strstart(uri, "rdma:", &p)) {
456         rdma_start_outgoing_migration(s, p, &local_err);
457 #endif
458 #if !defined(WIN32)
459     } else if (strstart(uri, "exec:", &p)) {
460         exec_start_outgoing_migration(s, p, &local_err);
461     } else if (strstart(uri, "unix:", &p)) {
462         unix_start_outgoing_migration(s, p, &local_err);
463     } else if (strstart(uri, "fd:", &p)) {
464         fd_start_outgoing_migration(s, p, &local_err);
465 #endif
466     } else {
467         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
468         s->state = MIG_STATE_ERROR;
469         return;
470     }
471 
472     if (local_err) {
473         migrate_fd_error(s);
474         error_propagate(errp, local_err);
475         return;
476     }
477 }
478 
479 void qmp_migrate_cancel(Error **errp)
480 {
481     migrate_fd_cancel(migrate_get_current());
482 }
483 
484 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
485 {
486     MigrationState *s = migrate_get_current();
487     int64_t new_size;
488 
489     /* Check for truncation */
490     if (value != (size_t)value) {
491         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
492                   "exceeding address space");
493         return;
494     }
495 
496     /* Cache should not be larger than guest ram size */
497     if (value > ram_bytes_total()) {
498         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
499                   "exceeds guest ram size ");
500         return;
501     }
502 
503     new_size = xbzrle_cache_resize(value);
504     if (new_size < 0) {
505         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
506                   "is smaller than page size");
507         return;
508     }
509 
510     s->xbzrle_cache_size = new_size;
511 }
512 
513 int64_t qmp_query_migrate_cache_size(Error **errp)
514 {
515     return migrate_xbzrle_cache_size();
516 }
517 
518 void qmp_migrate_set_speed(int64_t value, Error **errp)
519 {
520     MigrationState *s;
521 
522     if (value < 0) {
523         value = 0;
524     }
525     if (value > SIZE_MAX) {
526         value = SIZE_MAX;
527     }
528 
529     s = migrate_get_current();
530     s->bandwidth_limit = value;
531     if (s->file) {
532         qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
533     }
534 }
535 
536 void qmp_migrate_set_downtime(double value, Error **errp)
537 {
538     value *= 1e9;
539     value = MAX(0, MIN(UINT64_MAX, value));
540     max_downtime = (uint64_t)value;
541 }
542 
543 bool migrate_rdma_pin_all(void)
544 {
545     MigrationState *s;
546 
547     s = migrate_get_current();
548 
549     return s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL];
550 }
551 
552 bool migrate_auto_converge(void)
553 {
554     MigrationState *s;
555 
556     s = migrate_get_current();
557 
558     return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
559 }
560 
561 bool migrate_zero_blocks(void)
562 {
563     MigrationState *s;
564 
565     s = migrate_get_current();
566 
567     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
568 }
569 
570 int migrate_use_xbzrle(void)
571 {
572     MigrationState *s;
573 
574     s = migrate_get_current();
575 
576     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
577 }
578 
579 int64_t migrate_xbzrle_cache_size(void)
580 {
581     MigrationState *s;
582 
583     s = migrate_get_current();
584 
585     return s->xbzrle_cache_size;
586 }
587 
588 /* migration thread support */
589 
590 static void *migration_thread(void *opaque)
591 {
592     MigrationState *s = opaque;
593     int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
594     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
595     int64_t initial_bytes = 0;
596     int64_t max_size = 0;
597     int64_t start_time = initial_time;
598     bool old_vm_running = false;
599 
600     qemu_savevm_state_begin(s->file, &s->params);
601 
602     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
603     migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
604 
605     while (s->state == MIG_STATE_ACTIVE) {
606         int64_t current_time;
607         uint64_t pending_size;
608 
609         if (!qemu_file_rate_limit(s->file)) {
610             pending_size = qemu_savevm_state_pending(s->file, max_size);
611             trace_migrate_pending(pending_size, max_size);
612             if (pending_size && pending_size >= max_size) {
613                 qemu_savevm_state_iterate(s->file);
614             } else {
615                 int ret;
616 
617                 qemu_mutex_lock_iothread();
618                 start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
619                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
620                 old_vm_running = runstate_is_running();
621 
622                 ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
623                 if (ret >= 0) {
624                     qemu_file_set_rate_limit(s->file, INT64_MAX);
625                     qemu_savevm_state_complete(s->file);
626                 }
627                 qemu_mutex_unlock_iothread();
628 
629                 if (ret < 0) {
630                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
631                     break;
632                 }
633 
634                 if (!qemu_file_get_error(s->file)) {
635                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
636                     break;
637                 }
638             }
639         }
640 
641         if (qemu_file_get_error(s->file)) {
642             migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
643             break;
644         }
645         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
646         if (current_time >= initial_time + BUFFER_DELAY) {
647             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
648             uint64_t time_spent = current_time - initial_time;
649             double bandwidth = transferred_bytes / time_spent;
650             max_size = bandwidth * migrate_max_downtime() / 1000000;
651 
652             s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
653                     ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
654 
655             trace_migrate_transferred(transferred_bytes, time_spent,
656                                       bandwidth, max_size);
657             /* if we haven't sent anything, we don't want to recalculate
658                10000 is a small enough number for our purposes */
659             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
660                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
661             }
662 
663             qemu_file_reset_rate_limit(s->file);
664             initial_time = current_time;
665             initial_bytes = qemu_ftell(s->file);
666         }
667         if (qemu_file_rate_limit(s->file)) {
668             /* usleep expects microseconds */
669             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
670         }
671     }
672 
673     qemu_mutex_lock_iothread();
674     if (s->state == MIG_STATE_COMPLETED) {
675         int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
676         uint64_t transferred_bytes = qemu_ftell(s->file);
677         s->total_time = end_time - s->total_time;
678         s->downtime = end_time - start_time;
679         if (s->total_time) {
680             s->mbps = (((double) transferred_bytes * 8.0) /
681                        ((double) s->total_time)) / 1000;
682         }
683         runstate_set(RUN_STATE_POSTMIGRATE);
684     } else {
685         if (old_vm_running) {
686             vm_start();
687         }
688     }
689     qemu_bh_schedule(s->cleanup_bh);
690     qemu_mutex_unlock_iothread();
691 
692     return NULL;
693 }
694 
695 void migrate_fd_connect(MigrationState *s)
696 {
697     s->state = MIG_STATE_SETUP;
698     trace_migrate_set_state(MIG_STATE_SETUP);
699 
700     /* This is a best 1st approximation. ns to ms */
701     s->expected_downtime = max_downtime/1000000;
702     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
703 
704     qemu_file_set_rate_limit(s->file,
705                              s->bandwidth_limit / XFER_LIMIT_RATIO);
706 
707     /* Notify before starting migration thread */
708     notifier_list_notify(&migration_state_notifiers, s);
709 
710     qemu_thread_create(&s->thread, "migration", migration_thread, s,
711                        QEMU_THREAD_JOINABLE);
712 }
713