xref: /openbmc/qemu/migration/colo.c (revision de15df5e)
1 /*
2  * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
3  * (a.k.a. Fault Tolerance or Continuous Replication)
4  *
5  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
6  * Copyright (c) 2016 FUJITSU LIMITED
7  * Copyright (c) 2016 Intel Corporation
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2 or
10  * later.  See the COPYING file in the top-level directory.
11  */
12 
13 #include "qemu/osdep.h"
14 #include "sysemu/sysemu.h"
15 #include "qapi/error.h"
16 #include "qapi/qapi-commands-migration.h"
17 #include "qemu-file-channel.h"
18 #include "migration.h"
19 #include "qemu-file.h"
20 #include "savevm.h"
21 #include "migration/colo.h"
22 #include "block.h"
23 #include "io/channel-buffer.h"
24 #include "trace.h"
25 #include "qemu/error-report.h"
26 #include "qemu/main-loop.h"
27 #include "qemu/rcu.h"
28 #include "migration/failover.h"
29 #include "migration/ram.h"
30 #ifdef CONFIG_REPLICATION
31 #include "replication.h"
32 #endif
33 #include "net/colo-compare.h"
34 #include "net/colo.h"
35 #include "block/block.h"
36 #include "qapi/qapi-events-migration.h"
37 #include "qapi/qmp/qerror.h"
38 #include "sysemu/cpus.h"
39 #include "sysemu/runstate.h"
40 #include "net/filter.h"
41 
42 static bool vmstate_loading;
43 static Notifier packets_compare_notifier;
44 
45 /* User need to know colo mode after COLO failover */
46 static COLOMode last_colo_mode;
47 
48 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
49 
50 bool migration_in_colo_state(void)
51 {
52     MigrationState *s = migrate_get_current();
53 
54     return (s->state == MIGRATION_STATUS_COLO);
55 }
56 
57 bool migration_incoming_in_colo_state(void)
58 {
59     MigrationIncomingState *mis = migration_incoming_get_current();
60 
61     return mis && (mis->state == MIGRATION_STATUS_COLO);
62 }
63 
64 static bool colo_runstate_is_stopped(void)
65 {
66     return runstate_check(RUN_STATE_COLO) || !runstate_is_running();
67 }
68 
69 static void secondary_vm_do_failover(void)
70 {
71 /* COLO needs enable block-replication */
72 #ifdef CONFIG_REPLICATION
73     int old_state;
74     MigrationIncomingState *mis = migration_incoming_get_current();
75     Error *local_err = NULL;
76 
77     /* Can not do failover during the process of VM's loading VMstate, Or
78      * it will break the secondary VM.
79      */
80     if (vmstate_loading) {
81         old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
82                         FAILOVER_STATUS_RELAUNCH);
83         if (old_state != FAILOVER_STATUS_ACTIVE) {
84             error_report("Unknown error while do failover for secondary VM,"
85                          "old_state: %s", FailoverStatus_str(old_state));
86         }
87         return;
88     }
89 
90     migrate_set_state(&mis->state, MIGRATION_STATUS_COLO,
91                       MIGRATION_STATUS_COMPLETED);
92 
93     replication_stop_all(true, &local_err);
94     if (local_err) {
95         error_report_err(local_err);
96         local_err = NULL;
97     }
98 
99     /* Notify all filters of all NIC to do checkpoint */
100     colo_notify_filters_event(COLO_EVENT_FAILOVER, &local_err);
101     if (local_err) {
102         error_report_err(local_err);
103     }
104 
105     if (!autostart) {
106         error_report("\"-S\" qemu option will be ignored in secondary side");
107         /* recover runstate to normal migration finish state */
108         autostart = true;
109     }
110     /*
111      * Make sure COLO incoming thread not block in recv or send,
112      * If mis->from_src_file and mis->to_src_file use the same fd,
113      * The second shutdown() will return -1, we ignore this value,
114      * It is harmless.
115      */
116     if (mis->from_src_file) {
117         qemu_file_shutdown(mis->from_src_file);
118     }
119     if (mis->to_src_file) {
120         qemu_file_shutdown(mis->to_src_file);
121     }
122 
123     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
124                                    FAILOVER_STATUS_COMPLETED);
125     if (old_state != FAILOVER_STATUS_ACTIVE) {
126         error_report("Incorrect state (%s) while doing failover for "
127                      "secondary VM", FailoverStatus_str(old_state));
128         return;
129     }
130     /* Notify COLO incoming thread that failover work is finished */
131     qemu_sem_post(&mis->colo_incoming_sem);
132 
133     /* For Secondary VM, jump to incoming co */
134     if (mis->migration_incoming_co) {
135         qemu_coroutine_enter(mis->migration_incoming_co);
136     }
137 #else
138     abort();
139 #endif
140 }
141 
142 static void primary_vm_do_failover(void)
143 {
144 #ifdef CONFIG_REPLICATION
145     MigrationState *s = migrate_get_current();
146     int old_state;
147     Error *local_err = NULL;
148 
149     migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
150                       MIGRATION_STATUS_COMPLETED);
151     /*
152      * kick COLO thread which might wait at
153      * qemu_sem_wait(&s->colo_checkpoint_sem).
154      */
155     colo_checkpoint_notify(migrate_get_current());
156 
157     /*
158      * Wake up COLO thread which may blocked in recv() or send(),
159      * The s->rp_state.from_dst_file and s->to_dst_file may use the
160      * same fd, but we still shutdown the fd for twice, it is harmless.
161      */
162     if (s->to_dst_file) {
163         qemu_file_shutdown(s->to_dst_file);
164     }
165     if (s->rp_state.from_dst_file) {
166         qemu_file_shutdown(s->rp_state.from_dst_file);
167     }
168 
169     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
170                                    FAILOVER_STATUS_COMPLETED);
171     if (old_state != FAILOVER_STATUS_ACTIVE) {
172         error_report("Incorrect state (%s) while doing failover for Primary VM",
173                      FailoverStatus_str(old_state));
174         return;
175     }
176 
177     replication_stop_all(true, &local_err);
178     if (local_err) {
179         error_report_err(local_err);
180         local_err = NULL;
181     }
182 
183     /* Notify COLO thread that failover work is finished */
184     qemu_sem_post(&s->colo_exit_sem);
185 #else
186     abort();
187 #endif
188 }
189 
190 COLOMode get_colo_mode(void)
191 {
192     if (migration_in_colo_state()) {
193         return COLO_MODE_PRIMARY;
194     } else if (migration_incoming_in_colo_state()) {
195         return COLO_MODE_SECONDARY;
196     } else {
197         return COLO_MODE_NONE;
198     }
199 }
200 
201 void colo_do_failover(void)
202 {
203     /* Make sure VM stopped while failover happened. */
204     if (!colo_runstate_is_stopped()) {
205         vm_stop_force_state(RUN_STATE_COLO);
206     }
207 
208     switch (get_colo_mode()) {
209     case COLO_MODE_PRIMARY:
210         primary_vm_do_failover();
211         break;
212     case COLO_MODE_SECONDARY:
213         secondary_vm_do_failover();
214         break;
215     default:
216         error_report("colo_do_failover failed because the colo mode"
217                      " could not be obtained");
218     }
219 }
220 
221 #ifdef CONFIG_REPLICATION
222 void qmp_xen_set_replication(bool enable, bool primary,
223                              bool has_failover, bool failover,
224                              Error **errp)
225 {
226     ReplicationMode mode = primary ?
227                            REPLICATION_MODE_PRIMARY :
228                            REPLICATION_MODE_SECONDARY;
229 
230     if (has_failover && enable) {
231         error_setg(errp, "Parameter 'failover' is only for"
232                    " stopping replication");
233         return;
234     }
235 
236     if (enable) {
237         replication_start_all(mode, errp);
238     } else {
239         if (!has_failover) {
240             failover = NULL;
241         }
242         replication_stop_all(failover, failover ? NULL : errp);
243     }
244 }
245 
246 ReplicationStatus *qmp_query_xen_replication_status(Error **errp)
247 {
248     Error *err = NULL;
249     ReplicationStatus *s = g_new0(ReplicationStatus, 1);
250 
251     replication_get_error_all(&err);
252     if (err) {
253         s->error = true;
254         s->has_desc = true;
255         s->desc = g_strdup(error_get_pretty(err));
256     } else {
257         s->error = false;
258     }
259 
260     error_free(err);
261     return s;
262 }
263 
264 void qmp_xen_colo_do_checkpoint(Error **errp)
265 {
266     Error *err = NULL;
267 
268     replication_do_checkpoint_all(&err);
269     if (err) {
270         error_propagate(errp, err);
271         return;
272     }
273     /* Notify all filters of all NIC to do checkpoint */
274     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, errp);
275 }
276 #endif
277 
278 COLOStatus *qmp_query_colo_status(Error **errp)
279 {
280     COLOStatus *s = g_new0(COLOStatus, 1);
281 
282     s->mode = get_colo_mode();
283     s->last_mode = last_colo_mode;
284 
285     switch (failover_get_state()) {
286     case FAILOVER_STATUS_NONE:
287         s->reason = COLO_EXIT_REASON_NONE;
288         break;
289     case FAILOVER_STATUS_COMPLETED:
290         s->reason = COLO_EXIT_REASON_REQUEST;
291         break;
292     default:
293         if (migration_in_colo_state()) {
294             s->reason = COLO_EXIT_REASON_PROCESSING;
295         } else {
296             s->reason = COLO_EXIT_REASON_ERROR;
297         }
298     }
299 
300     return s;
301 }
302 
303 static void colo_send_message(QEMUFile *f, COLOMessage msg,
304                               Error **errp)
305 {
306     int ret;
307 
308     if (msg >= COLO_MESSAGE__MAX) {
309         error_setg(errp, "%s: Invalid message", __func__);
310         return;
311     }
312     qemu_put_be32(f, msg);
313     qemu_fflush(f);
314 
315     ret = qemu_file_get_error(f);
316     if (ret < 0) {
317         error_setg_errno(errp, -ret, "Can't send COLO message");
318     }
319     trace_colo_send_message(COLOMessage_str(msg));
320 }
321 
322 static void colo_send_message_value(QEMUFile *f, COLOMessage msg,
323                                     uint64_t value, Error **errp)
324 {
325     Error *local_err = NULL;
326     int ret;
327 
328     colo_send_message(f, msg, &local_err);
329     if (local_err) {
330         error_propagate(errp, local_err);
331         return;
332     }
333     qemu_put_be64(f, value);
334     qemu_fflush(f);
335 
336     ret = qemu_file_get_error(f);
337     if (ret < 0) {
338         error_setg_errno(errp, -ret, "Failed to send value for message:%s",
339                          COLOMessage_str(msg));
340     }
341 }
342 
343 static COLOMessage colo_receive_message(QEMUFile *f, Error **errp)
344 {
345     COLOMessage msg;
346     int ret;
347 
348     msg = qemu_get_be32(f);
349     ret = qemu_file_get_error(f);
350     if (ret < 0) {
351         error_setg_errno(errp, -ret, "Can't receive COLO message");
352         return msg;
353     }
354     if (msg >= COLO_MESSAGE__MAX) {
355         error_setg(errp, "%s: Invalid message", __func__);
356         return msg;
357     }
358     trace_colo_receive_message(COLOMessage_str(msg));
359     return msg;
360 }
361 
362 static void colo_receive_check_message(QEMUFile *f, COLOMessage expect_msg,
363                                        Error **errp)
364 {
365     COLOMessage msg;
366     Error *local_err = NULL;
367 
368     msg = colo_receive_message(f, &local_err);
369     if (local_err) {
370         error_propagate(errp, local_err);
371         return;
372     }
373     if (msg != expect_msg) {
374         error_setg(errp, "Unexpected COLO message %d, expected %d",
375                           msg, expect_msg);
376     }
377 }
378 
379 static uint64_t colo_receive_message_value(QEMUFile *f, uint32_t expect_msg,
380                                            Error **errp)
381 {
382     Error *local_err = NULL;
383     uint64_t value;
384     int ret;
385 
386     colo_receive_check_message(f, expect_msg, &local_err);
387     if (local_err) {
388         error_propagate(errp, local_err);
389         return 0;
390     }
391 
392     value = qemu_get_be64(f);
393     ret = qemu_file_get_error(f);
394     if (ret < 0) {
395         error_setg_errno(errp, -ret, "Failed to get value for COLO message: %s",
396                          COLOMessage_str(expect_msg));
397     }
398     return value;
399 }
400 
401 static int colo_do_checkpoint_transaction(MigrationState *s,
402                                           QIOChannelBuffer *bioc,
403                                           QEMUFile *fb)
404 {
405     Error *local_err = NULL;
406     int ret = -1;
407 
408     colo_send_message(s->to_dst_file, COLO_MESSAGE_CHECKPOINT_REQUEST,
409                       &local_err);
410     if (local_err) {
411         goto out;
412     }
413 
414     colo_receive_check_message(s->rp_state.from_dst_file,
415                     COLO_MESSAGE_CHECKPOINT_REPLY, &local_err);
416     if (local_err) {
417         goto out;
418     }
419     /* Reset channel-buffer directly */
420     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
421     bioc->usage = 0;
422 
423     qemu_mutex_lock_iothread();
424     if (failover_get_state() != FAILOVER_STATUS_NONE) {
425         qemu_mutex_unlock_iothread();
426         goto out;
427     }
428     vm_stop_force_state(RUN_STATE_COLO);
429     qemu_mutex_unlock_iothread();
430     trace_colo_vm_state_change("run", "stop");
431     /*
432      * Failover request bh could be called after vm_stop_force_state(),
433      * So we need check failover_request_is_active() again.
434      */
435     if (failover_get_state() != FAILOVER_STATUS_NONE) {
436         goto out;
437     }
438 
439     /* Disable block migration */
440     migrate_set_block_enabled(false, &local_err);
441     if (local_err) {
442         goto out;
443     }
444     qemu_mutex_lock_iothread();
445 
446 #ifdef CONFIG_REPLICATION
447     replication_do_checkpoint_all(&local_err);
448     if (local_err) {
449         qemu_mutex_unlock_iothread();
450         goto out;
451     }
452 #else
453         abort();
454 #endif
455 
456     colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
457     if (local_err) {
458         qemu_mutex_unlock_iothread();
459         goto out;
460     }
461     /* Note: device state is saved into buffer */
462     ret = qemu_save_device_state(fb);
463 
464     qemu_mutex_unlock_iothread();
465     if (ret < 0) {
466         goto out;
467     }
468     /*
469      * Only save VM's live state, which not including device state.
470      * TODO: We may need a timeout mechanism to prevent COLO process
471      * to be blocked here.
472      */
473     qemu_savevm_live_state(s->to_dst_file);
474 
475     qemu_fflush(fb);
476 
477     /*
478      * We need the size of the VMstate data in Secondary side,
479      * With which we can decide how much data should be read.
480      */
481     colo_send_message_value(s->to_dst_file, COLO_MESSAGE_VMSTATE_SIZE,
482                             bioc->usage, &local_err);
483     if (local_err) {
484         goto out;
485     }
486 
487     qemu_put_buffer(s->to_dst_file, bioc->data, bioc->usage);
488     qemu_fflush(s->to_dst_file);
489     ret = qemu_file_get_error(s->to_dst_file);
490     if (ret < 0) {
491         goto out;
492     }
493 
494     colo_receive_check_message(s->rp_state.from_dst_file,
495                        COLO_MESSAGE_VMSTATE_RECEIVED, &local_err);
496     if (local_err) {
497         goto out;
498     }
499 
500     qemu_event_reset(&s->colo_checkpoint_event);
501     colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT, &local_err);
502     if (local_err) {
503         goto out;
504     }
505 
506     colo_receive_check_message(s->rp_state.from_dst_file,
507                        COLO_MESSAGE_VMSTATE_LOADED, &local_err);
508     if (local_err) {
509         goto out;
510     }
511 
512     ret = 0;
513 
514     qemu_mutex_lock_iothread();
515     vm_start();
516     qemu_mutex_unlock_iothread();
517     trace_colo_vm_state_change("stop", "run");
518 
519 out:
520     if (local_err) {
521         error_report_err(local_err);
522     }
523     return ret;
524 }
525 
526 static void colo_compare_notify_checkpoint(Notifier *notifier, void *data)
527 {
528     colo_checkpoint_notify(data);
529 }
530 
531 static void colo_process_checkpoint(MigrationState *s)
532 {
533     QIOChannelBuffer *bioc;
534     QEMUFile *fb = NULL;
535     int64_t current_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
536     Error *local_err = NULL;
537     int ret;
538 
539     last_colo_mode = get_colo_mode();
540     if (last_colo_mode != COLO_MODE_PRIMARY) {
541         error_report("COLO mode must be COLO_MODE_PRIMARY");
542         return;
543     }
544 
545     failover_init_state();
546 
547     s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
548     if (!s->rp_state.from_dst_file) {
549         error_report("Open QEMUFile from_dst_file failed");
550         goto out;
551     }
552 
553     packets_compare_notifier.notify = colo_compare_notify_checkpoint;
554     colo_compare_register_notifier(&packets_compare_notifier);
555 
556     /*
557      * Wait for Secondary finish loading VM states and enter COLO
558      * restore.
559      */
560     colo_receive_check_message(s->rp_state.from_dst_file,
561                        COLO_MESSAGE_CHECKPOINT_READY, &local_err);
562     if (local_err) {
563         goto out;
564     }
565     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
566     fb = qemu_fopen_channel_output(QIO_CHANNEL(bioc));
567     object_unref(OBJECT(bioc));
568 
569     qemu_mutex_lock_iothread();
570 #ifdef CONFIG_REPLICATION
571     replication_start_all(REPLICATION_MODE_PRIMARY, &local_err);
572     if (local_err) {
573         qemu_mutex_unlock_iothread();
574         goto out;
575     }
576 #else
577         abort();
578 #endif
579 
580     vm_start();
581     qemu_mutex_unlock_iothread();
582     trace_colo_vm_state_change("stop", "run");
583 
584     timer_mod(s->colo_delay_timer,
585             current_time + s->parameters.x_checkpoint_delay);
586 
587     while (s->state == MIGRATION_STATUS_COLO) {
588         if (failover_get_state() != FAILOVER_STATUS_NONE) {
589             error_report("failover request");
590             goto out;
591         }
592 
593         qemu_event_wait(&s->colo_checkpoint_event);
594 
595         if (s->state != MIGRATION_STATUS_COLO) {
596             goto out;
597         }
598         ret = colo_do_checkpoint_transaction(s, bioc, fb);
599         if (ret < 0) {
600             goto out;
601         }
602     }
603 
604 out:
605     /* Throw the unreported error message after exited from loop */
606     if (local_err) {
607         error_report_err(local_err);
608     }
609 
610     if (fb) {
611         qemu_fclose(fb);
612     }
613 
614     /*
615      * There are only two reasons we can get here, some error happened
616      * or the user triggered failover.
617      */
618     switch (failover_get_state()) {
619     case FAILOVER_STATUS_COMPLETED:
620         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
621                                   COLO_EXIT_REASON_REQUEST);
622         break;
623     default:
624         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
625                                   COLO_EXIT_REASON_ERROR);
626     }
627 
628     /* Hope this not to be too long to wait here */
629     qemu_sem_wait(&s->colo_exit_sem);
630     qemu_sem_destroy(&s->colo_exit_sem);
631 
632     /*
633      * It is safe to unregister notifier after failover finished.
634      * Besides, colo_delay_timer and colo_checkpoint_sem can't be
635      * released befor unregister notifier, or there will be use-after-free
636      * error.
637      */
638     colo_compare_unregister_notifier(&packets_compare_notifier);
639     timer_del(s->colo_delay_timer);
640     timer_free(s->colo_delay_timer);
641     qemu_event_destroy(&s->colo_checkpoint_event);
642 
643     /*
644      * Must be called after failover BH is completed,
645      * Or the failover BH may shutdown the wrong fd that
646      * re-used by other threads after we release here.
647      */
648     if (s->rp_state.from_dst_file) {
649         qemu_fclose(s->rp_state.from_dst_file);
650     }
651 }
652 
653 void colo_checkpoint_notify(void *opaque)
654 {
655     MigrationState *s = opaque;
656     int64_t next_notify_time;
657 
658     qemu_event_set(&s->colo_checkpoint_event);
659     s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
660     next_notify_time = s->colo_checkpoint_time +
661                     s->parameters.x_checkpoint_delay;
662     timer_mod(s->colo_delay_timer, next_notify_time);
663 }
664 
665 void migrate_start_colo_process(MigrationState *s)
666 {
667     qemu_mutex_unlock_iothread();
668     qemu_event_init(&s->colo_checkpoint_event, false);
669     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
670                                 colo_checkpoint_notify, s);
671 
672     qemu_sem_init(&s->colo_exit_sem, 0);
673     migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
674                       MIGRATION_STATUS_COLO);
675     colo_process_checkpoint(s);
676     qemu_mutex_lock_iothread();
677 }
678 
679 static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
680                       QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
681 {
682     uint64_t total_size;
683     uint64_t value;
684     Error *local_err = NULL;
685     int ret;
686 
687     qemu_mutex_lock_iothread();
688     vm_stop_force_state(RUN_STATE_COLO);
689     trace_colo_vm_state_change("run", "stop");
690     qemu_mutex_unlock_iothread();
691 
692     /* FIXME: This is unnecessary for periodic checkpoint mode */
693     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
694                  &local_err);
695     if (local_err) {
696         error_propagate(errp, local_err);
697         return;
698     }
699 
700     colo_receive_check_message(mis->from_src_file,
701                        COLO_MESSAGE_VMSTATE_SEND, &local_err);
702     if (local_err) {
703         error_propagate(errp, local_err);
704         return;
705     }
706 
707     qemu_mutex_lock_iothread();
708     cpu_synchronize_all_states();
709     ret = qemu_loadvm_state_main(mis->from_src_file, mis);
710     qemu_mutex_unlock_iothread();
711 
712     if (ret < 0) {
713         error_setg(errp, "Load VM's live state (ram) error");
714         return;
715     }
716 
717     value = colo_receive_message_value(mis->from_src_file,
718                              COLO_MESSAGE_VMSTATE_SIZE, &local_err);
719     if (local_err) {
720         error_propagate(errp, local_err);
721         return;
722     }
723 
724     /*
725      * Read VM device state data into channel buffer,
726      * It's better to re-use the memory allocated.
727      * Here we need to handle the channel buffer directly.
728      */
729     if (value > bioc->capacity) {
730         bioc->capacity = value;
731         bioc->data = g_realloc(bioc->data, bioc->capacity);
732     }
733     total_size = qemu_get_buffer(mis->from_src_file, bioc->data, value);
734     if (total_size != value) {
735         error_setg(errp, "Got %" PRIu64 " VMState data, less than expected"
736                     " %" PRIu64, total_size, value);
737         return;
738     }
739     bioc->usage = total_size;
740     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
741 
742     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
743                  &local_err);
744     if (local_err) {
745         error_propagate(errp, local_err);
746         return;
747     }
748 
749     qemu_mutex_lock_iothread();
750     vmstate_loading = true;
751     colo_flush_ram_cache();
752     ret = qemu_load_device_state(fb);
753     if (ret < 0) {
754         error_setg(errp, "COLO: load device state failed");
755         vmstate_loading = false;
756         qemu_mutex_unlock_iothread();
757         return;
758     }
759 
760 #ifdef CONFIG_REPLICATION
761     replication_get_error_all(&local_err);
762     if (local_err) {
763         error_propagate(errp, local_err);
764         vmstate_loading = false;
765         qemu_mutex_unlock_iothread();
766         return;
767     }
768 
769     /* discard colo disk buffer */
770     replication_do_checkpoint_all(&local_err);
771     if (local_err) {
772         error_propagate(errp, local_err);
773         vmstate_loading = false;
774         qemu_mutex_unlock_iothread();
775         return;
776     }
777 #else
778     abort();
779 #endif
780     /* Notify all filters of all NIC to do checkpoint */
781     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, &local_err);
782 
783     if (local_err) {
784         error_propagate(errp, local_err);
785         vmstate_loading = false;
786         qemu_mutex_unlock_iothread();
787         return;
788     }
789 
790     vmstate_loading = false;
791     vm_start();
792     trace_colo_vm_state_change("stop", "run");
793     qemu_mutex_unlock_iothread();
794 
795     if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
796         return;
797     }
798 
799     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
800                  &local_err);
801     if (local_err) {
802         error_propagate(errp, local_err);
803     }
804 }
805 
806 static void colo_wait_handle_message(MigrationIncomingState *mis,
807                 QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
808 {
809     COLOMessage msg;
810     Error *local_err = NULL;
811 
812     msg = colo_receive_message(mis->from_src_file, &local_err);
813     if (local_err) {
814         error_propagate(errp, local_err);
815         return;
816     }
817 
818     switch (msg) {
819     case COLO_MESSAGE_CHECKPOINT_REQUEST:
820         colo_incoming_process_checkpoint(mis, fb, bioc, errp);
821         break;
822     default:
823         error_setg(errp, "Got unknown COLO message: %d", msg);
824         break;
825     }
826 }
827 
828 void *colo_process_incoming_thread(void *opaque)
829 {
830     MigrationIncomingState *mis = opaque;
831     QEMUFile *fb = NULL;
832     QIOChannelBuffer *bioc = NULL; /* Cache incoming device state */
833     Error *local_err = NULL;
834 
835     rcu_register_thread();
836     qemu_sem_init(&mis->colo_incoming_sem, 0);
837 
838     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
839                       MIGRATION_STATUS_COLO);
840 
841     last_colo_mode = get_colo_mode();
842     if (last_colo_mode != COLO_MODE_SECONDARY) {
843         error_report("COLO mode must be COLO_MODE_SECONDARY");
844         return NULL;
845     }
846 
847     failover_init_state();
848 
849     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
850     if (!mis->to_src_file) {
851         error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
852         goto out;
853     }
854     /*
855      * Note: the communication between Primary side and Secondary side
856      * should be sequential, we set the fd to unblocked in migration incoming
857      * coroutine, and here we are in the COLO incoming thread, so it is ok to
858      * set the fd back to blocked.
859      */
860     qemu_file_set_blocking(mis->from_src_file, true);
861 
862     colo_incoming_start_dirty_log();
863 
864     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
865     fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
866     object_unref(OBJECT(bioc));
867 
868     qemu_mutex_lock_iothread();
869 #ifdef CONFIG_REPLICATION
870     replication_start_all(REPLICATION_MODE_SECONDARY, &local_err);
871     if (local_err) {
872         qemu_mutex_unlock_iothread();
873         goto out;
874     }
875 #else
876         abort();
877 #endif
878     vm_start();
879     trace_colo_vm_state_change("stop", "run");
880     qemu_mutex_unlock_iothread();
881 
882     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
883                       &local_err);
884     if (local_err) {
885         goto out;
886     }
887 
888     while (mis->state == MIGRATION_STATUS_COLO) {
889         colo_wait_handle_message(mis, fb, bioc, &local_err);
890         if (local_err) {
891             error_report_err(local_err);
892             break;
893         }
894 
895         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
896             failover_set_state(FAILOVER_STATUS_RELAUNCH,
897                             FAILOVER_STATUS_NONE);
898             failover_request_active(NULL);
899             break;
900         }
901 
902         if (failover_get_state() != FAILOVER_STATUS_NONE) {
903             error_report("failover request");
904             break;
905         }
906     }
907 
908 out:
909     /*
910      * There are only two reasons we can get here, some error happened
911      * or the user triggered failover.
912      */
913     switch (failover_get_state()) {
914     case FAILOVER_STATUS_COMPLETED:
915         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
916                                   COLO_EXIT_REASON_REQUEST);
917         break;
918     default:
919         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
920                                   COLO_EXIT_REASON_ERROR);
921     }
922 
923     if (fb) {
924         qemu_fclose(fb);
925     }
926 
927     /* Hope this not to be too long to loop here */
928     qemu_sem_wait(&mis->colo_incoming_sem);
929     qemu_sem_destroy(&mis->colo_incoming_sem);
930     /* Must be called after failover BH is completed */
931     if (mis->to_src_file) {
932         qemu_fclose(mis->to_src_file);
933         mis->to_src_file = NULL;
934     }
935 
936     rcu_unregister_thread();
937     return NULL;
938 }
939