migration/colo.c

   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 "qemu/timer.h"
  15 #include "sysemu/sysemu.h"
  16 #include "qemu-file-channel.h"
  17 #include "migration/migration.h"
  18 #include "migration/qemu-file.h"
  19 #include "savevm.h"
  20 #include "migration/colo.h"
  21 #include "migration/block.h"
  22 #include "io/channel-buffer.h"
  23 #include "trace.h"
  24 #include "qemu/error-report.h"
  25 #include "qapi/error.h"
  26 #include "migration/failover.h"
  27 #include "replication.h"
  28 #include "qmp-commands.h"
  29
  30 static bool vmstate_loading;
  31
  32 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
  33
  34 bool colo_supported(void)
  35 {
  36     return true;
  37 }
  38
  39 bool migration_in_colo_state(void)
  40 {
  41     MigrationState *s = migrate_get_current();
  42
  43     return (s->state == MIGRATION_STATUS_COLO);
  44 }
  45
  46 bool migration_incoming_in_colo_state(void)
  47 {
  48     MigrationIncomingState *mis = migration_incoming_get_current();
  49
  50     return mis && (mis->state == MIGRATION_STATUS_COLO);
  51 }
  52
  53 static bool colo_runstate_is_stopped(void)
  54 {
  55     return runstate_check(RUN_STATE_COLO) || !runstate_is_running();
  56 }
  57
  58 static void secondary_vm_do_failover(void)
  59 {
  60     int old_state;
  61     MigrationIncomingState *mis = migration_incoming_get_current();
  62
  63     /* Can not do failover during the process of VM's loading VMstate, Or
  64      * it will break the secondary VM.
  65      */
  66     if (vmstate_loading) {
  67         old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
  68                         FAILOVER_STATUS_RELAUNCH);
  69         if (old_state != FAILOVER_STATUS_ACTIVE) {
  70             error_report("Unknown error while do failover for secondary VM,"
  71                          "old_state: %s", FailoverStatus_lookup[old_state]);
  72         }
  73         return;
  74     }
  75
  76     migrate_set_state(&mis->state, MIGRATION_STATUS_COLO,
  77                       MIGRATION_STATUS_COMPLETED);
  78
  79     if (!autostart) {
  80         error_report("\"-S\" qemu option will be ignored in secondary side");
  81         /* recover runstate to normal migration finish state */
  82         autostart = true;
  83     }
  84     /*
  85      * Make sure COLO incoming thread not block in recv or send,
  86      * If mis->from_src_file and mis->to_src_file use the same fd,
  87      * The second shutdown() will return -1, we ignore this value,
  88      * It is harmless.
  89      */
  90     if (mis->from_src_file) {
  91         qemu_file_shutdown(mis->from_src_file);
  92     }
  93     if (mis->to_src_file) {
  94         qemu_file_shutdown(mis->to_src_file);
  95     }
  96
  97     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
  98                                    FAILOVER_STATUS_COMPLETED);
  99     if (old_state != FAILOVER_STATUS_ACTIVE) {
 100         error_report("Incorrect state (%s) while doing failover for "
 101                      "secondary VM", FailoverStatus_lookup[old_state]);
 102         return;
 103     }
 104     /* Notify COLO incoming thread that failover work is finished */
 105     qemu_sem_post(&mis->colo_incoming_sem);
 106     /* For Secondary VM, jump to incoming co */
 107     if (mis->migration_incoming_co) {
 108         qemu_coroutine_enter(mis->migration_incoming_co);
 109     }
 110 }
 111
 112 static void primary_vm_do_failover(void)
 113 {
 114     MigrationState *s = migrate_get_current();
 115     int old_state;
 116
 117     migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
 118                       MIGRATION_STATUS_COMPLETED);
 119
 120     /*
 121      * Wake up COLO thread which may blocked in recv() or send(),
 122      * The s->rp_state.from_dst_file and s->to_dst_file may use the
 123      * same fd, but we still shutdown the fd for twice, it is harmless.
 124      */
 125     if (s->to_dst_file) {
 126         qemu_file_shutdown(s->to_dst_file);
 127     }
 128     if (s->rp_state.from_dst_file) {
 129         qemu_file_shutdown(s->rp_state.from_dst_file);
 130     }
 131
 132     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
 133                                    FAILOVER_STATUS_COMPLETED);
 134     if (old_state != FAILOVER_STATUS_ACTIVE) {
 135         error_report("Incorrect state (%s) while doing failover for Primary VM",
 136                      FailoverStatus_lookup[old_state]);
 137         return;
 138     }
 139     /* Notify COLO thread that failover work is finished */
 140     qemu_sem_post(&s->colo_exit_sem);
 141 }
 142
 143 void colo_do_failover(MigrationState *s)
 144 {
 145     /* Make sure VM stopped while failover happened. */
 146     if (!colo_runstate_is_stopped()) {
 147         vm_stop_force_state(RUN_STATE_COLO);
 148     }
 149
 150     if (get_colo_mode() == COLO_MODE_PRIMARY) {
 151         primary_vm_do_failover();
 152     } else {
 153         secondary_vm_do_failover();
 154     }
 155 }
 156
 157 void qmp_xen_set_replication(bool enable, bool primary,
 158                              bool has_failover, bool failover,
 159                              Error **errp)
 160 {
 161 #ifdef CONFIG_REPLICATION
 162     ReplicationMode mode = primary ?
 163                            REPLICATION_MODE_PRIMARY :
 164                            REPLICATION_MODE_SECONDARY;
 165
 166     if (has_failover && enable) {
 167         error_setg(errp, "Parameter 'failover' is only for"
 168                    " stopping replication");
 169         return;
 170     }
 171
 172     if (enable) {
 173         replication_start_all(mode, errp);
 174     } else {
 175         if (!has_failover) {
 176             failover = NULL;
 177         }
 178         replication_stop_all(failover, failover ? NULL : errp);
 179     }
 180 #else
 181     abort();
 182 #endif
 183 }
 184
 185 ReplicationStatus *qmp_query_xen_replication_status(Error **errp)
 186 {
 187 #ifdef CONFIG_REPLICATION
 188     Error *err = NULL;
 189     ReplicationStatus *s = g_new0(ReplicationStatus, 1);
 190
 191     replication_get_error_all(&err);
 192     if (err) {
 193         s->error = true;
 194         s->has_desc = true;
 195         s->desc = g_strdup(error_get_pretty(err));
 196     } else {
 197         s->error = false;
 198     }
 199
 200     error_free(err);
 201     return s;
 202 #else
 203     abort();
 204 #endif
 205 }
 206
 207 void qmp_xen_colo_do_checkpoint(Error **errp)
 208 {
 209 #ifdef CONFIG_REPLICATION
 210     replication_do_checkpoint_all(errp);
 211 #else
 212     abort();
 213 #endif
 214 }
 215
 216 static void colo_send_message(QEMUFile *f, COLOMessage msg,
 217                               Error **errp)
 218 {
 219     int ret;
 220
 221     if (msg >= COLO_MESSAGE__MAX) {
 222         error_setg(errp, "%s: Invalid message", __func__);
 223         return;
 224     }
 225     qemu_put_be32(f, msg);
 226     qemu_fflush(f);
 227
 228     ret = qemu_file_get_error(f);
 229     if (ret < 0) {
 230         error_setg_errno(errp, -ret, "Can't send COLO message");
 231     }
 232     trace_colo_send_message(COLOMessage_lookup[msg]);
 233 }
 234
 235 static void colo_send_message_value(QEMUFile *f, COLOMessage msg,
 236                                     uint64_t value, Error **errp)
 237 {
 238     Error *local_err = NULL;
 239     int ret;
 240
 241     colo_send_message(f, msg, &local_err);
 242     if (local_err) {
 243         error_propagate(errp, local_err);
 244         return;
 245     }
 246     qemu_put_be64(f, value);
 247     qemu_fflush(f);
 248
 249     ret = qemu_file_get_error(f);
 250     if (ret < 0) {
 251         error_setg_errno(errp, -ret, "Failed to send value for message:%s",
 252                          COLOMessage_lookup[msg]);
 253     }
 254 }
 255
 256 static COLOMessage colo_receive_message(QEMUFile *f, Error **errp)
 257 {
 258     COLOMessage msg;
 259     int ret;
 260
 261     msg = qemu_get_be32(f);
 262     ret = qemu_file_get_error(f);
 263     if (ret < 0) {
 264         error_setg_errno(errp, -ret, "Can't receive COLO message");
 265         return msg;
 266     }
 267     if (msg >= COLO_MESSAGE__MAX) {
 268         error_setg(errp, "%s: Invalid message", __func__);
 269         return msg;
 270     }
 271     trace_colo_receive_message(COLOMessage_lookup[msg]);
 272     return msg;
 273 }
 274
 275 static void colo_receive_check_message(QEMUFile *f, COLOMessage expect_msg,
 276                                        Error **errp)
 277 {
 278     COLOMessage msg;
 279     Error *local_err = NULL;
 280
 281     msg = colo_receive_message(f, &local_err);
 282     if (local_err) {
 283         error_propagate(errp, local_err);
 284         return;
 285     }
 286     if (msg != expect_msg) {
 287         error_setg(errp, "Unexpected COLO message %d, expected %d",
 288                           msg, expect_msg);
 289     }
 290 }
 291
 292 static uint64_t colo_receive_message_value(QEMUFile *f, uint32_t expect_msg,
 293                                            Error **errp)
 294 {
 295     Error *local_err = NULL;
 296     uint64_t value;
 297     int ret;
 298
 299     colo_receive_check_message(f, expect_msg, &local_err);
 300     if (local_err) {
 301         error_propagate(errp, local_err);
 302         return 0;
 303     }
 304
 305     value = qemu_get_be64(f);
 306     ret = qemu_file_get_error(f);
 307     if (ret < 0) {
 308         error_setg_errno(errp, -ret, "Failed to get value for COLO message: %s",
 309                          COLOMessage_lookup[expect_msg]);
 310     }
 311     return value;
 312 }
 313
 314 static int colo_do_checkpoint_transaction(MigrationState *s,
 315                                           QIOChannelBuffer *bioc,
 316                                           QEMUFile *fb)
 317 {
 318     Error *local_err = NULL;
 319     int ret = -1;
 320
 321     colo_send_message(s->to_dst_file, COLO_MESSAGE_CHECKPOINT_REQUEST,
 322                       &local_err);
 323     if (local_err) {
 324         goto out;
 325     }
 326
 327     colo_receive_check_message(s->rp_state.from_dst_file,
 328                     COLO_MESSAGE_CHECKPOINT_REPLY, &local_err);
 329     if (local_err) {
 330         goto out;
 331     }
 332     /* Reset channel-buffer directly */
 333     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 334     bioc->usage = 0;
 335
 336     qemu_mutex_lock_iothread();
 337     if (failover_get_state() != FAILOVER_STATUS_NONE) {
 338         qemu_mutex_unlock_iothread();
 339         goto out;
 340     }
 341     vm_stop_force_state(RUN_STATE_COLO);
 342     qemu_mutex_unlock_iothread();
 343     trace_colo_vm_state_change("run", "stop");
 344     /*
 345      * Failover request bh could be called after vm_stop_force_state(),
 346      * So we need check failover_request_is_active() again.
 347      */
 348     if (failover_get_state() != FAILOVER_STATUS_NONE) {
 349         goto out;
 350     }
 351
 352     /* Disable block migration */
 353     migrate_set_block_enabled(false, &local_err);
 354     qemu_savevm_state_header(fb);
 355     qemu_savevm_state_begin(fb);
 356     qemu_mutex_lock_iothread();
 357     qemu_savevm_state_complete_precopy(fb, false);
 358     qemu_mutex_unlock_iothread();
 359
 360     qemu_fflush(fb);
 361
 362     colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
 363     if (local_err) {
 364         goto out;
 365     }
 366     /*
 367      * We need the size of the VMstate data in Secondary side,
 368      * With which we can decide how much data should be read.
 369      */
 370     colo_send_message_value(s->to_dst_file, COLO_MESSAGE_VMSTATE_SIZE,
 371                             bioc->usage, &local_err);
 372     if (local_err) {
 373         goto out;
 374     }
 375
 376     qemu_put_buffer(s->to_dst_file, bioc->data, bioc->usage);
 377     qemu_fflush(s->to_dst_file);
 378     ret = qemu_file_get_error(s->to_dst_file);
 379     if (ret < 0) {
 380         goto out;
 381     }
 382
 383     colo_receive_check_message(s->rp_state.from_dst_file,
 384                        COLO_MESSAGE_VMSTATE_RECEIVED, &local_err);
 385     if (local_err) {
 386         goto out;
 387     }
 388
 389     colo_receive_check_message(s->rp_state.from_dst_file,
 390                        COLO_MESSAGE_VMSTATE_LOADED, &local_err);
 391     if (local_err) {
 392         goto out;
 393     }
 394
 395     ret = 0;
 396
 397     qemu_mutex_lock_iothread();
 398     vm_start();
 399     qemu_mutex_unlock_iothread();
 400     trace_colo_vm_state_change("stop", "run");
 401
 402 out:
 403     if (local_err) {
 404         error_report_err(local_err);
 405     }
 406     return ret;
 407 }
 408
 409 static void colo_process_checkpoint(MigrationState *s)
 410 {
 411     QIOChannelBuffer *bioc;
 412     QEMUFile *fb = NULL;
 413     int64_t current_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 414     Error *local_err = NULL;
 415     int ret;
 416
 417     failover_init_state();
 418
 419     s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
 420     if (!s->rp_state.from_dst_file) {
 421         error_report("Open QEMUFile from_dst_file failed");
 422         goto out;
 423     }
 424
 425     /*
 426      * Wait for Secondary finish loading VM states and enter COLO
 427      * restore.
 428      */
 429     colo_receive_check_message(s->rp_state.from_dst_file,
 430                        COLO_MESSAGE_CHECKPOINT_READY, &local_err);
 431     if (local_err) {
 432         goto out;
 433     }
 434     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 435     fb = qemu_fopen_channel_output(QIO_CHANNEL(bioc));
 436     object_unref(OBJECT(bioc));
 437
 438     qemu_mutex_lock_iothread();
 439     vm_start();
 440     qemu_mutex_unlock_iothread();
 441     trace_colo_vm_state_change("stop", "run");
 442
 443     timer_mod(s->colo_delay_timer,
 444             current_time + s->parameters.x_checkpoint_delay);
 445
 446     while (s->state == MIGRATION_STATUS_COLO) {
 447         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 448             error_report("failover request");
 449             goto out;
 450         }
 451
 452         qemu_sem_wait(&s->colo_checkpoint_sem);
 453
 454         ret = colo_do_checkpoint_transaction(s, bioc, fb);
 455         if (ret < 0) {
 456             goto out;
 457         }
 458     }
 459
 460 out:
 461     /* Throw the unreported error message after exited from loop */
 462     if (local_err) {
 463         error_report_err(local_err);
 464     }
 465
 466     if (fb) {
 467         qemu_fclose(fb);
 468     }
 469
 470     timer_del(s->colo_delay_timer);
 471
 472     /* Hope this not to be too long to wait here */
 473     qemu_sem_wait(&s->colo_exit_sem);
 474     qemu_sem_destroy(&s->colo_exit_sem);
 475     /*
 476      * Must be called after failover BH is completed,
 477      * Or the failover BH may shutdown the wrong fd that
 478      * re-used by other threads after we release here.
 479      */
 480     if (s->rp_state.from_dst_file) {
 481         qemu_fclose(s->rp_state.from_dst_file);
 482     }
 483 }
 484
 485 void colo_checkpoint_notify(void *opaque)
 486 {
 487     MigrationState *s = opaque;
 488     int64_t next_notify_time;
 489
 490     qemu_sem_post(&s->colo_checkpoint_sem);
 491     s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 492     next_notify_time = s->colo_checkpoint_time +
 493                     s->parameters.x_checkpoint_delay;
 494     timer_mod(s->colo_delay_timer, next_notify_time);
 495 }
 496
 497 void migrate_start_colo_process(MigrationState *s)
 498 {
 499     qemu_mutex_unlock_iothread();
 500     qemu_sem_init(&s->colo_checkpoint_sem, 0);
 501     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
 502                                 colo_checkpoint_notify, s);
 503
 504     qemu_sem_init(&s->colo_exit_sem, 0);
 505     migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
 506                       MIGRATION_STATUS_COLO);
 507     colo_process_checkpoint(s);
 508     qemu_mutex_lock_iothread();
 509 }
 510
 511 static void colo_wait_handle_message(QEMUFile *f, int *checkpoint_request,
 512                                      Error **errp)
 513 {
 514     COLOMessage msg;
 515     Error *local_err = NULL;
 516
 517     msg = colo_receive_message(f, &local_err);
 518     if (local_err) {
 519         error_propagate(errp, local_err);
 520         return;
 521     }
 522
 523     switch (msg) {
 524     case COLO_MESSAGE_CHECKPOINT_REQUEST:
 525         *checkpoint_request = 1;
 526         break;
 527     default:
 528         *checkpoint_request = 0;
 529         error_setg(errp, "Got unknown COLO message: %d", msg);
 530         break;
 531     }
 532 }
 533
 534 void *colo_process_incoming_thread(void *opaque)
 535 {
 536     MigrationIncomingState *mis = opaque;
 537     QEMUFile *fb = NULL;
 538     QIOChannelBuffer *bioc = NULL; /* Cache incoming device state */
 539     uint64_t total_size;
 540     uint64_t value;
 541     Error *local_err = NULL;
 542
 543     qemu_sem_init(&mis->colo_incoming_sem, 0);
 544
 545     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
 546                       MIGRATION_STATUS_COLO);
 547
 548     failover_init_state();
 549
 550     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
 551     if (!mis->to_src_file) {
 552         error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
 553         goto out;
 554     }
 555     /*
 556      * Note: the communication between Primary side and Secondary side
 557      * should be sequential, we set the fd to unblocked in migration incoming
 558      * coroutine, and here we are in the COLO incoming thread, so it is ok to
 559      * set the fd back to blocked.
 560      */
 561     qemu_file_set_blocking(mis->from_src_file, true);
 562
 563     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 564     fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
 565     object_unref(OBJECT(bioc));
 566
 567     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
 568                       &local_err);
 569     if (local_err) {
 570         goto out;
 571     }
 572
 573     while (mis->state == MIGRATION_STATUS_COLO) {
 574         int request = 0;
 575
 576         colo_wait_handle_message(mis->from_src_file, &request, &local_err);
 577         if (local_err) {
 578             goto out;
 579         }
 580         assert(request);
 581         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 582             error_report("failover request");
 583             goto out;
 584         }
 585
 586         /* FIXME: This is unnecessary for periodic checkpoint mode */
 587         colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
 588                      &local_err);
 589         if (local_err) {
 590             goto out;
 591         }
 592
 593         colo_receive_check_message(mis->from_src_file,
 594                            COLO_MESSAGE_VMSTATE_SEND, &local_err);
 595         if (local_err) {
 596             goto out;
 597         }
 598
 599         value = colo_receive_message_value(mis->from_src_file,
 600                                  COLO_MESSAGE_VMSTATE_SIZE, &local_err);
 601         if (local_err) {
 602             goto out;
 603         }
 604
 605         /*
 606          * Read VM device state data into channel buffer,
 607          * It's better to re-use the memory allocated.
 608          * Here we need to handle the channel buffer directly.
 609          */
 610         if (value > bioc->capacity) {
 611             bioc->capacity = value;
 612             bioc->data = g_realloc(bioc->data, bioc->capacity);
 613         }
 614         total_size = qemu_get_buffer(mis->from_src_file, bioc->data, value);
 615         if (total_size != value) {
 616             error_report("Got %" PRIu64 " VMState data, less than expected"
 617                         " %" PRIu64, total_size, value);
 618             goto out;
 619         }
 620         bioc->usage = total_size;
 621         qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 622
 623         colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
 624                      &local_err);
 625         if (local_err) {
 626             goto out;
 627         }
 628
 629         qemu_mutex_lock_iothread();
 630         qemu_system_reset(SHUTDOWN_CAUSE_NONE);
 631         vmstate_loading = true;
 632         if (qemu_loadvm_state(fb) < 0) {
 633             error_report("COLO: loadvm failed");
 634             qemu_mutex_unlock_iothread();
 635             goto out;
 636         }
 637
 638         vmstate_loading = false;
 639         qemu_mutex_unlock_iothread();
 640
 641         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 642             failover_set_state(FAILOVER_STATUS_RELAUNCH,
 643                             FAILOVER_STATUS_NONE);
 644             failover_request_active(NULL);
 645             goto out;
 646         }
 647
 648         colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
 649                      &local_err);
 650         if (local_err) {
 651             goto out;
 652         }
 653     }
 654
 655 out:
 656     vmstate_loading = false;
 657     /* Throw the unreported error message after exited from loop */
 658     if (local_err) {
 659         error_report_err(local_err);
 660     }
 661
 662     if (fb) {
 663         qemu_fclose(fb);
 664     }
 665
 666     /* Hope this not to be too long to loop here */
 667     qemu_sem_wait(&mis->colo_incoming_sem);
 668     qemu_sem_destroy(&mis->colo_incoming_sem);
 669     /* Must be called after failover BH is completed */
 670     if (mis->to_src_file) {
 671         qemu_fclose(mis->to_src_file);
 672     }
 673     migration_incoming_exit_colo();
 674
 675     return NULL;
 676 }