migration/block-dirty-bitmap.c

   1 /*
   2  * Block dirty bitmap postcopy migration
   3  *
   4  * Copyright IBM, Corp. 2009
   5  * Copyright (c) 2016-2017 Virtuozzo International GmbH. All rights reserved.
   6  *
   7  * Authors:
   8  *  Liran Schour   <lirans@il.ibm.com>
   9  *  Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2.  See
  12  * the COPYING file in the top-level directory.
  13  * This file is derived from migration/block.c, so it's author and IBM copyright
  14  * are here, although content is quite different.
  15  *
  16  * Contributions after 2012-01-13 are licensed under the terms of the
  17  * GNU GPL, version 2 or (at your option) any later version.
  18  *
  19  *                                ***
  20  *
  21  * Here postcopy migration of dirty bitmaps is realized. Only QMP-addressable
  22  * bitmaps are migrated.
  23  *
  24  * Bitmap migration implies creating bitmap with the same name and granularity
  25  * in destination QEMU. If the bitmap with the same name (for the same node)
  26  * already exists on destination an error will be generated.
  27  *
  28  * format of migration:
  29  *
  30  * # Header (shared for different chunk types)
  31  * 1, 2 or 4 bytes: flags (see qemu_{put,put}_flags)
  32  * [ 1 byte: node name size ] \  flags & DEVICE_NAME
  33  * [ n bytes: node name     ] /
  34  * [ 1 byte: bitmap name size ] \  flags & BITMAP_NAME
  35  * [ n bytes: bitmap name     ] /
  36  *
  37  * # Start of bitmap migration (flags & START)
  38  * header
  39  * be64: granularity
  40  * 1 byte: bitmap flags (corresponds to BdrvDirtyBitmap)
  41  *   bit 0    -  bitmap is enabled
  42  *   bit 1    -  bitmap is persistent
  43  *   bit 2    -  bitmap is autoloading
  44  *   bits 3-7 - reserved, must be zero
  45  *
  46  * # Complete of bitmap migration (flags & COMPLETE)
  47  * header
  48  *
  49  * # Data chunk of bitmap migration
  50  * header
  51  * be64: start sector
  52  * be32: number of sectors
  53  * [ be64: buffer size  ] \ ! (flags & ZEROES)
  54  * [ n bytes: buffer    ] /
  55  *
  56  * The last chunk in stream should contain flags & EOS. The chunk may skip
  57  * device and/or bitmap names, assuming them to be the same with the previous
  58  * chunk.
  59  */
  60
  61 #include "qemu/osdep.h"
  62 #include "block/block.h"
  63 #include "block/block_int.h"
  64 #include "sysemu/block-backend.h"
  65 #include "qemu/main-loop.h"
  66 #include "qemu/error-report.h"
  67 #include "migration/misc.h"
  68 #include "migration/migration.h"
  69 #include "qemu-file.h"
  70 #include "migration/vmstate.h"
  71 #include "migration/register.h"
  72 #include "qemu/hbitmap.h"
  73 #include "sysemu/sysemu.h"
  74 #include "qemu/cutils.h"
  75 #include "qapi/error.h"
  76 #include "trace.h"
  77
  78 #define CHUNK_SIZE     (1 << 10)
  79
  80 /* Flags occupy one, two or four bytes (Big Endian). The size is determined as
  81  * follows:
  82  * in first (most significant) byte bit 8 is clear  -->  one byte
  83  * in first byte bit 8 is set    -->  two or four bytes, depending on second
  84  *                                    byte:
  85  *    | in second byte bit 8 is clear  -->  two bytes
  86  *    | in second byte bit 8 is set    -->  four bytes
  87  */
  88 #define DIRTY_BITMAP_MIG_FLAG_EOS           0x01
  89 #define DIRTY_BITMAP_MIG_FLAG_ZEROES        0x02
  90 #define DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME   0x04
  91 #define DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME   0x08
  92 #define DIRTY_BITMAP_MIG_FLAG_START         0x10
  93 #define DIRTY_BITMAP_MIG_FLAG_COMPLETE      0x20
  94 #define DIRTY_BITMAP_MIG_FLAG_BITS          0x40
  95
  96 #define DIRTY_BITMAP_MIG_EXTRA_FLAGS        0x80
  97
  98 #define DIRTY_BITMAP_MIG_START_FLAG_ENABLED          0x01
  99 #define DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT       0x02
 100 /* 0x04 was "AUTOLOAD" flags on elder versions, no it is ignored */
 101 #define DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK    0xf8
 102
 103 typedef struct DirtyBitmapMigBitmapState {
 104     /* Written during setup phase. */
 105     BlockDriverState *bs;
 106     const char *node_name;
 107     BdrvDirtyBitmap *bitmap;
 108     uint64_t total_sectors;
 109     uint64_t sectors_per_chunk;
 110     QSIMPLEQ_ENTRY(DirtyBitmapMigBitmapState) entry;
 111     uint8_t flags;
 112
 113     /* For bulk phase. */
 114     bool bulk_completed;
 115     uint64_t cur_sector;
 116 } DirtyBitmapMigBitmapState;
 117
 118 typedef struct DirtyBitmapMigState {
 119     QSIMPLEQ_HEAD(, DirtyBitmapMigBitmapState) dbms_list;
 120
 121     bool bulk_completed;
 122     bool no_bitmaps;
 123
 124     /* for send_bitmap_bits() */
 125     BlockDriverState *prev_bs;
 126     BdrvDirtyBitmap *prev_bitmap;
 127 } DirtyBitmapMigState;
 128
 129 typedef struct DirtyBitmapLoadState {
 130     uint32_t flags;
 131     char node_name[256];
 132     char bitmap_name[256];
 133     BlockDriverState *bs;
 134     BdrvDirtyBitmap *bitmap;
 135 } DirtyBitmapLoadState;
 136
 137 static DirtyBitmapMigState dirty_bitmap_mig_state;
 138
 139 typedef struct DirtyBitmapLoadBitmapState {
 140     BlockDriverState *bs;
 141     BdrvDirtyBitmap *bitmap;
 142     bool migrated;
 143 } DirtyBitmapLoadBitmapState;
 144 static GSList *enabled_bitmaps;
 145 QemuMutex finish_lock;
 146
 147 void init_dirty_bitmap_incoming_migration(void)
 148 {
 149     qemu_mutex_init(&finish_lock);
 150 }
 151
 152 static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
 153 {
 154     uint8_t flags = qemu_get_byte(f);
 155     if (flags & DIRTY_BITMAP_MIG_EXTRA_FLAGS) {
 156         flags = flags << 8 | qemu_get_byte(f);
 157         if (flags & DIRTY_BITMAP_MIG_EXTRA_FLAGS) {
 158             flags = flags << 16 | qemu_get_be16(f);
 159         }
 160     }
 161
 162     return flags;
 163 }
 164
 165 static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
 166 {
 167     /* The code currently do not send flags more than one byte */
 168     assert(!(flags & (0xffffff00 | DIRTY_BITMAP_MIG_EXTRA_FLAGS)));
 169
 170     qemu_put_byte(f, flags);
 171 }
 172
 173 static void send_bitmap_header(QEMUFile *f, DirtyBitmapMigBitmapState *dbms,
 174                                uint32_t additional_flags)
 175 {
 176     BlockDriverState *bs = dbms->bs;
 177     BdrvDirtyBitmap *bitmap = dbms->bitmap;
 178     uint32_t flags = additional_flags;
 179     trace_send_bitmap_header_enter();
 180
 181     if (bs != dirty_bitmap_mig_state.prev_bs) {
 182         dirty_bitmap_mig_state.prev_bs = bs;
 183         flags |= DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME;
 184     }
 185
 186     if (bitmap != dirty_bitmap_mig_state.prev_bitmap) {
 187         dirty_bitmap_mig_state.prev_bitmap = bitmap;
 188         flags |= DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME;
 189     }
 190
 191     qemu_put_bitmap_flags(f, flags);
 192
 193     if (flags & DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME) {
 194         qemu_put_counted_string(f, dbms->node_name);
 195     }
 196
 197     if (flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
 198         qemu_put_counted_string(f, bdrv_dirty_bitmap_name(bitmap));
 199     }
 200 }
 201
 202 static void send_bitmap_start(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
 203 {
 204     send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_START);
 205     qemu_put_be32(f, bdrv_dirty_bitmap_granularity(dbms->bitmap));
 206     qemu_put_byte(f, dbms->flags);
 207 }
 208
 209 static void send_bitmap_complete(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
 210 {
 211     send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
 212 }
 213
 214 static void send_bitmap_bits(QEMUFile *f, DirtyBitmapMigBitmapState *dbms,
 215                              uint64_t start_sector, uint32_t nr_sectors)
 216 {
 217     /* align for buffer_is_zero() */
 218     uint64_t align = 4 * sizeof(long);
 219     uint64_t unaligned_size =
 220         bdrv_dirty_bitmap_serialization_size(
 221             dbms->bitmap, start_sector << BDRV_SECTOR_BITS,
 222             (uint64_t)nr_sectors << BDRV_SECTOR_BITS);
 223     uint64_t buf_size = QEMU_ALIGN_UP(unaligned_size, align);
 224     uint8_t *buf = g_malloc0(buf_size);
 225     uint32_t flags = DIRTY_BITMAP_MIG_FLAG_BITS;
 226
 227     bdrv_dirty_bitmap_serialize_part(
 228         dbms->bitmap, buf, start_sector << BDRV_SECTOR_BITS,
 229         (uint64_t)nr_sectors << BDRV_SECTOR_BITS);
 230
 231     if (buffer_is_zero(buf, buf_size)) {
 232         g_free(buf);
 233         buf = NULL;
 234         flags |= DIRTY_BITMAP_MIG_FLAG_ZEROES;
 235     }
 236
 237     trace_send_bitmap_bits(flags, start_sector, nr_sectors, buf_size);
 238
 239     send_bitmap_header(f, dbms, flags);
 240
 241     qemu_put_be64(f, start_sector);
 242     qemu_put_be32(f, nr_sectors);
 243
 244     /* if a block is zero we need to flush here since the network
 245      * bandwidth is now a lot higher than the storage device bandwidth.
 246      * thus if we queue zero blocks we slow down the migration. */
 247     if (flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
 248         qemu_fflush(f);
 249     } else {
 250         qemu_put_be64(f, buf_size);
 251         qemu_put_buffer(f, buf, buf_size);
 252     }
 253
 254     g_free(buf);
 255 }
 256
 257 /* Called with iothread lock taken.  */
 258 static void dirty_bitmap_mig_cleanup(void)
 259 {
 260     DirtyBitmapMigBitmapState *dbms;
 261
 262     while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
 263         QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
 264         bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
 265         bdrv_unref(dbms->bs);
 266         g_free(dbms);
 267     }
 268 }
 269
 270 /* Called with iothread lock taken. */
 271 static int init_dirty_bitmap_migration(void)
 272 {
 273     BlockDriverState *bs;
 274     BdrvDirtyBitmap *bitmap;
 275     DirtyBitmapMigBitmapState *dbms;
 276     Error *local_err = NULL;
 277
 278     dirty_bitmap_mig_state.bulk_completed = false;
 279     dirty_bitmap_mig_state.prev_bs = NULL;
 280     dirty_bitmap_mig_state.prev_bitmap = NULL;
 281     dirty_bitmap_mig_state.no_bitmaps = false;
 282
 283     for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
 284         const char *name = bdrv_get_device_or_node_name(bs);
 285
 286         for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap;
 287              bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
 288         {
 289             if (!bdrv_dirty_bitmap_name(bitmap)) {
 290                 continue;
 291             }
 292
 293             if (!name || strcmp(name, "") == 0) {
 294                 error_report("Found bitmap '%s' in unnamed node %p. It can't "
 295                              "be migrated", bdrv_dirty_bitmap_name(bitmap), bs);
 296                 goto fail;
 297             }
 298
 299             if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT,
 300                                         &local_err)) {
 301                 error_report_err(local_err);
 302                 goto fail;
 303             }
 304
 305             bdrv_ref(bs);
 306             bdrv_dirty_bitmap_set_busy(bitmap, true);
 307
 308             dbms = g_new0(DirtyBitmapMigBitmapState, 1);
 309             dbms->bs = bs;
 310             dbms->node_name = name;
 311             dbms->bitmap = bitmap;
 312             dbms->total_sectors = bdrv_nb_sectors(bs);
 313             dbms->sectors_per_chunk = CHUNK_SIZE * 8 *
 314                 bdrv_dirty_bitmap_granularity(bitmap) >> BDRV_SECTOR_BITS;
 315             if (bdrv_dirty_bitmap_enabled(bitmap)) {
 316                 dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
 317             }
 318             if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
 319                 dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
 320             }
 321
 322             QSIMPLEQ_INSERT_TAIL(&dirty_bitmap_mig_state.dbms_list,
 323                                  dbms, entry);
 324         }
 325     }
 326
 327     /* unset migration flags here, to not roll back it */
 328     QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
 329         bdrv_dirty_bitmap_set_migration(dbms->bitmap, true);
 330     }
 331
 332     if (QSIMPLEQ_EMPTY(&dirty_bitmap_mig_state.dbms_list)) {
 333         dirty_bitmap_mig_state.no_bitmaps = true;
 334     }
 335
 336     return 0;
 337
 338 fail:
 339     dirty_bitmap_mig_cleanup();
 340
 341     return -1;
 342 }
 343
 344 /* Called with no lock taken.  */
 345 static void bulk_phase_send_chunk(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
 346 {
 347     uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
 348                              dbms->sectors_per_chunk);
 349
 350     send_bitmap_bits(f, dbms, dbms->cur_sector, nr_sectors);
 351
 352     dbms->cur_sector += nr_sectors;
 353     if (dbms->cur_sector >= dbms->total_sectors) {
 354         dbms->bulk_completed = true;
 355     }
 356 }
 357
 358 /* Called with no lock taken.  */
 359 static void bulk_phase(QEMUFile *f, bool limit)
 360 {
 361     DirtyBitmapMigBitmapState *dbms;
 362
 363     QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
 364         while (!dbms->bulk_completed) {
 365             bulk_phase_send_chunk(f, dbms);
 366             if (limit && qemu_file_rate_limit(f)) {
 367                 return;
 368             }
 369         }
 370     }
 371
 372     dirty_bitmap_mig_state.bulk_completed = true;
 373 }
 374
 375 /* for SaveVMHandlers */
 376 static void dirty_bitmap_save_cleanup(void *opaque)
 377 {
 378     dirty_bitmap_mig_cleanup();
 379 }
 380
 381 static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
 382 {
 383     trace_dirty_bitmap_save_iterate(migration_in_postcopy());
 384
 385     if (migration_in_postcopy() && !dirty_bitmap_mig_state.bulk_completed) {
 386         bulk_phase(f, true);
 387     }
 388
 389     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
 390
 391     return dirty_bitmap_mig_state.bulk_completed;
 392 }
 393
 394 /* Called with iothread lock taken.  */
 395
 396 static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
 397 {
 398     DirtyBitmapMigBitmapState *dbms;
 399     trace_dirty_bitmap_save_complete_enter();
 400
 401     if (!dirty_bitmap_mig_state.bulk_completed) {
 402         bulk_phase(f, false);
 403     }
 404
 405     QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
 406         send_bitmap_complete(f, dbms);
 407     }
 408
 409     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
 410
 411     trace_dirty_bitmap_save_complete_finish();
 412
 413     dirty_bitmap_mig_cleanup();
 414     return 0;
 415 }
 416
 417 static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
 418                                       uint64_t max_size,
 419                                       uint64_t *res_precopy_only,
 420                                       uint64_t *res_compatible,
 421                                       uint64_t *res_postcopy_only)
 422 {
 423     DirtyBitmapMigBitmapState *dbms;
 424     uint64_t pending = 0;
 425
 426     qemu_mutex_lock_iothread();
 427
 428     QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
 429         uint64_t gran = bdrv_dirty_bitmap_granularity(dbms->bitmap);
 430         uint64_t sectors = dbms->bulk_completed ? 0 :
 431                            dbms->total_sectors - dbms->cur_sector;
 432
 433         pending += DIV_ROUND_UP(sectors * BDRV_SECTOR_SIZE, gran);
 434     }
 435
 436     qemu_mutex_unlock_iothread();
 437
 438     trace_dirty_bitmap_save_pending(pending, max_size);
 439
 440     *res_postcopy_only += pending;
 441 }
 442
 443 /* First occurrence of this bitmap. It should be created if doesn't exist */
 444 static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
 445 {
 446     Error *local_err = NULL;
 447     uint32_t granularity = qemu_get_be32(f);
 448     uint8_t flags = qemu_get_byte(f);
 449
 450     if (s->bitmap) {
 451         error_report("Bitmap with the same name ('%s') already exists on "
 452                      "destination", bdrv_dirty_bitmap_name(s->bitmap));
 453         return -EINVAL;
 454     } else {
 455         s->bitmap = bdrv_create_dirty_bitmap(s->bs, granularity,
 456                                              s->bitmap_name, &local_err);
 457         if (!s->bitmap) {
 458             error_report_err(local_err);
 459             return -EINVAL;
 460         }
 461     }
 462
 463     if (flags & DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK) {
 464         error_report("Unknown flags in migrated dirty bitmap header: %x",
 465                      flags);
 466         return -EINVAL;
 467     }
 468
 469     if (flags & DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT) {
 470         bdrv_dirty_bitmap_set_persistence(s->bitmap, true);
 471     }
 472
 473     bdrv_disable_dirty_bitmap(s->bitmap);
 474     if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
 475         DirtyBitmapLoadBitmapState *b;
 476
 477         bdrv_dirty_bitmap_create_successor(s->bs, s->bitmap, &local_err);
 478         if (local_err) {
 479             error_report_err(local_err);
 480             return -EINVAL;
 481         }
 482
 483         b = g_new(DirtyBitmapLoadBitmapState, 1);
 484         b->bs = s->bs;
 485         b->bitmap = s->bitmap;
 486         b->migrated = false;
 487         enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
 488     }
 489
 490     return 0;
 491 }
 492
 493 void dirty_bitmap_mig_before_vm_start(void)
 494 {
 495     GSList *item;
 496
 497     qemu_mutex_lock(&finish_lock);
 498
 499     for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
 500         DirtyBitmapLoadBitmapState *b = item->data;
 501
 502         if (b->migrated) {
 503             bdrv_enable_dirty_bitmap_locked(b->bitmap);
 504         } else {
 505             bdrv_dirty_bitmap_enable_successor(b->bitmap);
 506         }
 507
 508         g_free(b);
 509     }
 510
 511     g_slist_free(enabled_bitmaps);
 512     enabled_bitmaps = NULL;
 513
 514     qemu_mutex_unlock(&finish_lock);
 515 }
 516
 517 static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
 518 {
 519     GSList *item;
 520     trace_dirty_bitmap_load_complete();
 521     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);
 522
 523     qemu_mutex_lock(&finish_lock);
 524
 525     for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
 526         DirtyBitmapLoadBitmapState *b = item->data;
 527
 528         if (b->bitmap == s->bitmap) {
 529             b->migrated = true;
 530             break;
 531         }
 532     }
 533
 534     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
 535         bdrv_dirty_bitmap_lock(s->bitmap);
 536         if (enabled_bitmaps == NULL) {
 537             /* in postcopy */
 538             bdrv_reclaim_dirty_bitmap_locked(s->bs, s->bitmap, &error_abort);
 539             bdrv_enable_dirty_bitmap_locked(s->bitmap);
 540         } else {
 541             /* target not started, successor must be empty */
 542             int64_t count = bdrv_get_dirty_count(s->bitmap);
 543             BdrvDirtyBitmap *ret = bdrv_reclaim_dirty_bitmap_locked(s->bs,
 544                                                                     s->bitmap,
 545                                                                     NULL);
 546             /* bdrv_reclaim_dirty_bitmap can fail only on no successor (it
 547              * must be) or on merge fail, but merge can't fail when second
 548              * bitmap is empty
 549              */
 550             assert(ret == s->bitmap &&
 551                    count == bdrv_get_dirty_count(s->bitmap));
 552         }
 553         bdrv_dirty_bitmap_unlock(s->bitmap);
 554     }
 555
 556     qemu_mutex_unlock(&finish_lock);
 557 }
 558
 559 static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *s)
 560 {
 561     uint64_t first_byte = qemu_get_be64(f) << BDRV_SECTOR_BITS;
 562     uint64_t nr_bytes = (uint64_t)qemu_get_be32(f) << BDRV_SECTOR_BITS;
 563     trace_dirty_bitmap_load_bits_enter(first_byte >> BDRV_SECTOR_BITS,
 564                                        nr_bytes >> BDRV_SECTOR_BITS);
 565
 566     if (s->flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
 567         trace_dirty_bitmap_load_bits_zeroes();
 568         bdrv_dirty_bitmap_deserialize_zeroes(s->bitmap, first_byte, nr_bytes,
 569                                              false);
 570     } else {
 571         size_t ret;
 572         uint8_t *buf;
 573         uint64_t buf_size = qemu_get_be64(f);
 574         uint64_t needed_size =
 575             bdrv_dirty_bitmap_serialization_size(s->bitmap,
 576                                                  first_byte, nr_bytes);
 577
 578         if (needed_size > buf_size ||
 579             buf_size > QEMU_ALIGN_UP(needed_size, 4 * sizeof(long))
 580              /* Here used same alignment as in send_bitmap_bits */
 581         ) {
 582             error_report("Migrated bitmap granularity doesn't "
 583                          "match the destination bitmap '%s' granularity",
 584                          bdrv_dirty_bitmap_name(s->bitmap));
 585             return -EINVAL;
 586         }
 587
 588         buf = g_malloc(buf_size);
 589         ret = qemu_get_buffer(f, buf, buf_size);
 590         if (ret != buf_size) {
 591             error_report("Failed to read bitmap bits");
 592             g_free(buf);
 593             return -EIO;
 594         }
 595
 596         bdrv_dirty_bitmap_deserialize_part(s->bitmap, buf, first_byte, nr_bytes,
 597                                            false);
 598         g_free(buf);
 599     }
 600
 601     return 0;
 602 }
 603
 604 static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
 605 {
 606     Error *local_err = NULL;
 607     bool nothing;
 608     s->flags = qemu_get_bitmap_flags(f);
 609     trace_dirty_bitmap_load_header(s->flags);
 610
 611     nothing = s->flags == (s->flags & DIRTY_BITMAP_MIG_FLAG_EOS);
 612
 613     if (s->flags & DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME) {
 614         if (!qemu_get_counted_string(f, s->node_name)) {
 615             error_report("Unable to read node name string");
 616             return -EINVAL;
 617         }
 618         s->bs = bdrv_lookup_bs(s->node_name, s->node_name, &local_err);
 619         if (!s->bs) {
 620             error_report_err(local_err);
 621             return -EINVAL;
 622         }
 623     } else if (!s->bs && !nothing) {
 624         error_report("Error: block device name is not set");
 625         return -EINVAL;
 626     }
 627
 628     if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
 629         if (!qemu_get_counted_string(f, s->bitmap_name)) {
 630             error_report("Unable to read bitmap name string");
 631             return -EINVAL;
 632         }
 633         s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
 634
 635         /* bitmap may be NULL here, it wouldn't be an error if it is the
 636          * first occurrence of the bitmap */
 637         if (!s->bitmap && !(s->flags & DIRTY_BITMAP_MIG_FLAG_START)) {
 638             error_report("Error: unknown dirty bitmap "
 639                          "'%s' for block device '%s'",
 640                          s->bitmap_name, s->node_name);
 641             return -EINVAL;
 642         }
 643     } else if (!s->bitmap && !nothing) {
 644         error_report("Error: block device name is not set");
 645         return -EINVAL;
 646     }
 647
 648     return 0;
 649 }
 650
 651 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 652 {
 653     static DirtyBitmapLoadState s;
 654     int ret = 0;
 655
 656     trace_dirty_bitmap_load_enter();
 657
 658     if (version_id != 1) {
 659         return -EINVAL;
 660     }
 661
 662     do {
 663         ret = dirty_bitmap_load_header(f, &s);
 664         if (ret < 0) {
 665             return ret;
 666         }
 667
 668         if (s.flags & DIRTY_BITMAP_MIG_FLAG_START) {
 669             ret = dirty_bitmap_load_start(f, &s);
 670         } else if (s.flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
 671             dirty_bitmap_load_complete(f, &s);
 672         } else if (s.flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
 673             ret = dirty_bitmap_load_bits(f, &s);
 674         }
 675
 676         if (!ret) {
 677             ret = qemu_file_get_error(f);
 678         }
 679
 680         if (ret) {
 681             return ret;
 682         }
 683     } while (!(s.flags & DIRTY_BITMAP_MIG_FLAG_EOS));
 684
 685     trace_dirty_bitmap_load_success();
 686     return 0;
 687 }
 688
 689 static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
 690 {
 691     DirtyBitmapMigBitmapState *dbms = NULL;
 692     if (init_dirty_bitmap_migration() < 0) {
 693         return -1;
 694     }
 695
 696     QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
 697         send_bitmap_start(f, dbms);
 698     }
 699     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
 700
 701     return 0;
 702 }
 703
 704 static bool dirty_bitmap_is_active(void *opaque)
 705 {
 706     return migrate_dirty_bitmaps() && !dirty_bitmap_mig_state.no_bitmaps;
 707 }
 708
 709 static bool dirty_bitmap_is_active_iterate(void *opaque)
 710 {
 711     return dirty_bitmap_is_active(opaque) && !runstate_is_running();
 712 }
 713
 714 static bool dirty_bitmap_has_postcopy(void *opaque)
 715 {
 716     return true;
 717 }
 718
 719 static SaveVMHandlers savevm_dirty_bitmap_handlers = {
 720     .save_setup = dirty_bitmap_save_setup,
 721     .save_live_complete_postcopy = dirty_bitmap_save_complete,
 722     .save_live_complete_precopy = dirty_bitmap_save_complete,
 723     .has_postcopy = dirty_bitmap_has_postcopy,
 724     .save_live_pending = dirty_bitmap_save_pending,
 725     .save_live_iterate = dirty_bitmap_save_iterate,
 726     .is_active_iterate = dirty_bitmap_is_active_iterate,
 727     .load_state = dirty_bitmap_load,
 728     .save_cleanup = dirty_bitmap_save_cleanup,
 729     .is_active = dirty_bitmap_is_active,
 730 };
 731
 732 void dirty_bitmap_mig_init(void)
 733 {
 734     QSIMPLEQ_INIT(&dirty_bitmap_mig_state.dbms_list);
 735
 736     register_savevm_live(NULL, "dirty-bitmap", 0, 1,
 737                          &savevm_dirty_bitmap_handlers,
 738                          &dirty_bitmap_mig_state);
 739 }