block-migration.c

   1 /*
   2  * QEMU live block migration
   3  *
   4  * Copyright IBM, Corp. 2009
   5  *
   6  * Authors:
   7  *  Liran Schour   <[email protected]>
   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 "block/block_int.h"
  18 #include "hw/hw.h"
  19 #include "qemu/queue.h"
  20 #include "qemu/timer.h"
  21 #include "migration/block.h"
  22 #include "migration/migration.h"
  23 #include "sysemu/blockdev.h"
  24 #include <assert.h>
  25
  26 #define BLOCK_SIZE                       (1 << 20)
  27 #define BDRV_SECTORS_PER_DIRTY_CHUNK     (BLOCK_SIZE >> BDRV_SECTOR_BITS)
  28
  29 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  30 #define BLK_MIG_FLAG_EOS                0x02
  31 #define BLK_MIG_FLAG_PROGRESS           0x04
  32 #define BLK_MIG_FLAG_ZERO_BLOCK         0x08
  33
  34 #define MAX_IS_ALLOCATED_SEARCH 65536
  35
  36 //#define DEBUG_BLK_MIGRATION
  37
  38 #ifdef DEBUG_BLK_MIGRATION
  39 #define DPRINTF(fmt, ...) \
  40     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  41 #else
  42 #define DPRINTF(fmt, ...) \
  43     do { } while (0)
  44 #endif
  45
  46 typedef struct BlkMigDevState {
  47     /* Written during setup phase.  Can be read without a lock.  */
  48     BlockDriverState *bs;
  49     int shared_base;
  50     int64_t total_sectors;
  51     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  52
  53     /* Only used by migration thread.  Does not need a lock.  */
  54     int bulk_completed;
  55     int64_t cur_sector;
  56     int64_t cur_dirty;
  57
  58     /* Protected by block migration lock.  */
  59     unsigned long *aio_bitmap;
  60     int64_t completed_sectors;
  61     BdrvDirtyBitmap *dirty_bitmap;
  62     Error *blocker;
  63 } BlkMigDevState;
  64
  65 typedef struct BlkMigBlock {
  66     /* Only used by migration thread.  */
  67     uint8_t *buf;
  68     BlkMigDevState *bmds;
  69     int64_t sector;
  70     int nr_sectors;
  71     struct iovec iov;
  72     QEMUIOVector qiov;
  73     BlockDriverAIOCB *aiocb;
  74
  75     /* Protected by block migration lock.  */
  76     int ret;
  77     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  78 } BlkMigBlock;
  79
  80 typedef struct BlkMigState {
  81     /* Written during setup phase.  Can be read without a lock.  */
  82     int blk_enable;
  83     int shared_base;
  84     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  85     int64_t total_sector_sum;
  86     bool zero_blocks;
  87
  88     /* Protected by lock.  */
  89     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  90     int submitted;
  91     int read_done;
  92
  93     /* Only used by migration thread.  Does not need a lock.  */
  94     int transferred;
  95     int prev_progress;
  96     int bulk_completed;
  97
  98     /* Lock must be taken _inside_ the iothread lock.  */
  99     QemuMutex lock;
 100 } BlkMigState;
 101
 102 static BlkMigState block_mig_state;
 103
 104 static void blk_mig_lock(void)
 105 {
 106     qemu_mutex_lock(&block_mig_state.lock);
 107 }
 108
 109 static void blk_mig_unlock(void)
 110 {
 111     qemu_mutex_unlock(&block_mig_state.lock);
 112 }
 113
 114 /* Must run outside of the iothread lock during the bulk phase,
 115  * or the VM will stall.
 116  */
 117
 118 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
 119 {
 120     int len;
 121     uint64_t flags = BLK_MIG_FLAG_DEVICE_BLOCK;
 122
 123     if (block_mig_state.zero_blocks &&
 124         buffer_is_zero(blk->buf, BLOCK_SIZE)) {
 125         flags |= BLK_MIG_FLAG_ZERO_BLOCK;
 126     }
 127
 128     /* sector number and flags */
 129     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
 130                      | flags);
 131
 132     /* device name */
 133     len = strlen(blk->bmds->bs->device_name);
 134     qemu_put_byte(f, len);
 135     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
 136
 137     /* if a block is zero we need to flush here since the network
 138      * bandwidth is now a lot higher than the storage device bandwidth.
 139      * thus if we queue zero blocks we slow down the migration */
 140     if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
 141         qemu_fflush(f);
 142         return;
 143     }
 144
 145     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 146 }
 147
 148 int blk_mig_active(void)
 149 {
 150     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 151 }
 152
 153 uint64_t blk_mig_bytes_transferred(void)
 154 {
 155     BlkMigDevState *bmds;
 156     uint64_t sum = 0;
 157
 158     blk_mig_lock();
 159     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 160         sum += bmds->completed_sectors;
 161     }
 162     blk_mig_unlock();
 163     return sum << BDRV_SECTOR_BITS;
 164 }
 165
 166 uint64_t blk_mig_bytes_remaining(void)
 167 {
 168     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 169 }
 170
 171 uint64_t blk_mig_bytes_total(void)
 172 {
 173     BlkMigDevState *bmds;
 174     uint64_t sum = 0;
 175
 176     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 177         sum += bmds->total_sectors;
 178     }
 179     return sum << BDRV_SECTOR_BITS;
 180 }
 181
 182
 183 /* Called with migration lock held.  */
 184
 185 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 186 {
 187     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 188
 189     if (sector < bdrv_nb_sectors(bmds->bs)) {
 190         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 191             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 192     } else {
 193         return 0;
 194     }
 195 }
 196
 197 /* Called with migration lock held.  */
 198
 199 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 200                              int nb_sectors, int set)
 201 {
 202     int64_t start, end;
 203     unsigned long val, idx, bit;
 204
 205     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 206     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 207
 208     for (; start <= end; start++) {
 209         idx = start / (sizeof(unsigned long) * 8);
 210         bit = start % (sizeof(unsigned long) * 8);
 211         val = bmds->aio_bitmap[idx];
 212         if (set) {
 213             val |= 1UL << bit;
 214         } else {
 215             val &= ~(1UL << bit);
 216         }
 217         bmds->aio_bitmap[idx] = val;
 218     }
 219 }
 220
 221 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 222 {
 223     BlockDriverState *bs = bmds->bs;
 224     int64_t bitmap_size;
 225
 226     bitmap_size = bdrv_nb_sectors(bs) + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 227     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 228
 229     bmds->aio_bitmap = g_malloc0(bitmap_size);
 230 }
 231
 232 /* Never hold migration lock when yielding to the main loop!  */
 233
 234 static void blk_mig_read_cb(void *opaque, int ret)
 235 {
 236     BlkMigBlock *blk = opaque;
 237
 238     blk_mig_lock();
 239     blk->ret = ret;
 240
 241     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 242     bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
 243
 244     block_mig_state.submitted--;
 245     block_mig_state.read_done++;
 246     assert(block_mig_state.submitted >= 0);
 247     blk_mig_unlock();
 248 }
 249
 250 /* Called with no lock taken.  */
 251
 252 static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
 253 {
 254     int64_t total_sectors = bmds->total_sectors;
 255     int64_t cur_sector = bmds->cur_sector;
 256     BlockDriverState *bs = bmds->bs;
 257     BlkMigBlock *blk;
 258     int nr_sectors;
 259
 260     if (bmds->shared_base) {
 261         qemu_mutex_lock_iothread();
 262         while (cur_sector < total_sectors &&
 263                !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
 264                                   &nr_sectors)) {
 265             cur_sector += nr_sectors;
 266         }
 267         qemu_mutex_unlock_iothread();
 268     }
 269
 270     if (cur_sector >= total_sectors) {
 271         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 272         return 1;
 273     }
 274
 275     bmds->completed_sectors = cur_sector;
 276
 277     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 278
 279     /* we are going to transfer a full block even if it is not allocated */
 280     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 281
 282     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 283         nr_sectors = total_sectors - cur_sector;
 284     }
 285
 286     blk = g_new(BlkMigBlock, 1);
 287     blk->buf = g_malloc(BLOCK_SIZE);
 288     blk->bmds = bmds;
 289     blk->sector = cur_sector;
 290     blk->nr_sectors = nr_sectors;
 291
 292     blk->iov.iov_base = blk->buf;
 293     blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 294     qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 295
 296     blk_mig_lock();
 297     block_mig_state.submitted++;
 298     blk_mig_unlock();
 299
 300     qemu_mutex_lock_iothread();
 301     blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
 302                                 nr_sectors, blk_mig_read_cb, blk);
 303
 304     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
 305     qemu_mutex_unlock_iothread();
 306
 307     bmds->cur_sector = cur_sector + nr_sectors;
 308     return (bmds->cur_sector >= total_sectors);
 309 }
 310
 311 /* Called with iothread lock taken.  */
 312
 313 static int set_dirty_tracking(void)
 314 {
 315     BlkMigDevState *bmds;
 316     int ret;
 317
 318     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 319         bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE,
 320                                                       NULL);
 321         if (!bmds->dirty_bitmap) {
 322             ret = -errno;
 323             goto fail;
 324         }
 325     }
 326     return 0;
 327
 328 fail:
 329     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 330         if (bmds->dirty_bitmap) {
 331             bdrv_release_dirty_bitmap(bmds->bs, bmds->dirty_bitmap);
 332         }
 333     }
 334     return ret;
 335 }
 336
 337 static void unset_dirty_tracking(void)
 338 {
 339     BlkMigDevState *bmds;
 340
 341     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 342         bdrv_release_dirty_bitmap(bmds->bs, bmds->dirty_bitmap);
 343     }
 344 }
 345
 346 static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
 347 {
 348     BlkMigDevState *bmds;
 349     int64_t sectors;
 350
 351     if (!bdrv_is_read_only(bs)) {
 352         sectors = bdrv_nb_sectors(bs);
 353         if (sectors <= 0) {
 354             return;
 355         }
 356
 357         bmds = g_new0(BlkMigDevState, 1);
 358         bmds->bs = bs;
 359         bmds->bulk_completed = 0;
 360         bmds->total_sectors = sectors;
 361         bmds->completed_sectors = 0;
 362         bmds->shared_base = block_mig_state.shared_base;
 363         alloc_aio_bitmap(bmds);
 364         error_setg(&bmds->blocker, "block device is in use by migration");
 365         bdrv_op_block_all(bs, bmds->blocker);
 366         bdrv_ref(bs);
 367
 368         block_mig_state.total_sector_sum += sectors;
 369
 370         if (bmds->shared_base) {
 371             DPRINTF("Start migration for %s with shared base image\n",
 372                     bs->device_name);
 373         } else {
 374             DPRINTF("Start full migration for %s\n", bs->device_name);
 375         }
 376
 377         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 378     }
 379 }
 380
 381 static void init_blk_migration(QEMUFile *f)
 382 {
 383     block_mig_state.submitted = 0;
 384     block_mig_state.read_done = 0;
 385     block_mig_state.transferred = 0;
 386     block_mig_state.total_sector_sum = 0;
 387     block_mig_state.prev_progress = -1;
 388     block_mig_state.bulk_completed = 0;
 389     block_mig_state.zero_blocks = migrate_zero_blocks();
 390
 391     bdrv_iterate(init_blk_migration_it, NULL);
 392 }
 393
 394 /* Called with no lock taken.  */
 395
 396 static int blk_mig_save_bulked_block(QEMUFile *f)
 397 {
 398     int64_t completed_sector_sum = 0;
 399     BlkMigDevState *bmds;
 400     int progress;
 401     int ret = 0;
 402
 403     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 404         if (bmds->bulk_completed == 0) {
 405             if (mig_save_device_bulk(f, bmds) == 1) {
 406                 /* completed bulk section for this device */
 407                 bmds->bulk_completed = 1;
 408             }
 409             completed_sector_sum += bmds->completed_sectors;
 410             ret = 1;
 411             break;
 412         } else {
 413             completed_sector_sum += bmds->completed_sectors;
 414         }
 415     }
 416
 417     if (block_mig_state.total_sector_sum != 0) {
 418         progress = completed_sector_sum * 100 /
 419                    block_mig_state.total_sector_sum;
 420     } else {
 421         progress = 100;
 422     }
 423     if (progress != block_mig_state.prev_progress) {
 424         block_mig_state.prev_progress = progress;
 425         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 426                          | BLK_MIG_FLAG_PROGRESS);
 427         DPRINTF("Completed %d %%\r", progress);
 428     }
 429
 430     return ret;
 431 }
 432
 433 static void blk_mig_reset_dirty_cursor(void)
 434 {
 435     BlkMigDevState *bmds;
 436
 437     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 438         bmds->cur_dirty = 0;
 439     }
 440 }
 441
 442 /* Called with iothread lock taken.  */
 443
 444 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
 445                                  int is_async)
 446 {
 447     BlkMigBlock *blk;
 448     int64_t total_sectors = bmds->total_sectors;
 449     int64_t sector;
 450     int nr_sectors;
 451     int ret = -EIO;
 452
 453     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 454         blk_mig_lock();
 455         if (bmds_aio_inflight(bmds, sector)) {
 456             blk_mig_unlock();
 457             bdrv_drain_all();
 458         } else {
 459             blk_mig_unlock();
 460         }
 461         if (bdrv_get_dirty(bmds->bs, bmds->dirty_bitmap, sector)) {
 462
 463             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 464                 nr_sectors = total_sectors - sector;
 465             } else {
 466                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 467             }
 468             blk = g_new(BlkMigBlock, 1);
 469             blk->buf = g_malloc(BLOCK_SIZE);
 470             blk->bmds = bmds;
 471             blk->sector = sector;
 472             blk->nr_sectors = nr_sectors;
 473
 474             if (is_async) {
 475                 blk->iov.iov_base = blk->buf;
 476                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 477                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 478
 479                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 480                                             nr_sectors, blk_mig_read_cb, blk);
 481
 482                 blk_mig_lock();
 483                 block_mig_state.submitted++;
 484                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 485                 blk_mig_unlock();
 486             } else {
 487                 ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
 488                 if (ret < 0) {
 489                     goto error;
 490                 }
 491                 blk_send(f, blk);
 492
 493                 g_free(blk->buf);
 494                 g_free(blk);
 495             }
 496
 497             bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
 498             break;
 499         }
 500         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 501         bmds->cur_dirty = sector;
 502     }
 503
 504     return (bmds->cur_dirty >= bmds->total_sectors);
 505
 506 error:
 507     DPRINTF("Error reading sector %" PRId64 "\n", sector);
 508     g_free(blk->buf);
 509     g_free(blk);
 510     return ret;
 511 }
 512
 513 /* Called with iothread lock taken.
 514  *
 515  * return value:
 516  * 0: too much data for max_downtime
 517  * 1: few enough data for max_downtime
 518 */
 519 static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
 520 {
 521     BlkMigDevState *bmds;
 522     int ret = 1;
 523
 524     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 525         ret = mig_save_device_dirty(f, bmds, is_async);
 526         if (ret <= 0) {
 527             break;
 528         }
 529     }
 530
 531     return ret;
 532 }
 533
 534 /* Called with no locks taken.  */
 535
 536 static int flush_blks(QEMUFile *f)
 537 {
 538     BlkMigBlock *blk;
 539     int ret = 0;
 540
 541     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 542             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 543             block_mig_state.transferred);
 544
 545     blk_mig_lock();
 546     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 547         if (qemu_file_rate_limit(f)) {
 548             break;
 549         }
 550         if (blk->ret < 0) {
 551             ret = blk->ret;
 552             break;
 553         }
 554
 555         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 556         blk_mig_unlock();
 557         blk_send(f, blk);
 558         blk_mig_lock();
 559
 560         g_free(blk->buf);
 561         g_free(blk);
 562
 563         block_mig_state.read_done--;
 564         block_mig_state.transferred++;
 565         assert(block_mig_state.read_done >= 0);
 566     }
 567     blk_mig_unlock();
 568
 569     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 570             block_mig_state.submitted, block_mig_state.read_done,
 571             block_mig_state.transferred);
 572     return ret;
 573 }
 574
 575 /* Called with iothread lock taken.  */
 576
 577 static int64_t get_remaining_dirty(void)
 578 {
 579     BlkMigDevState *bmds;
 580     int64_t dirty = 0;
 581
 582     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 583         dirty += bdrv_get_dirty_count(bmds->bs, bmds->dirty_bitmap);
 584     }
 585
 586     return dirty << BDRV_SECTOR_BITS;
 587 }
 588
 589 /* Called with iothread lock taken.  */
 590
 591 static void blk_mig_cleanup(void)
 592 {
 593     BlkMigDevState *bmds;
 594     BlkMigBlock *blk;
 595
 596     bdrv_drain_all();
 597
 598     unset_dirty_tracking();
 599
 600     blk_mig_lock();
 601     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 602         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 603         bdrv_op_unblock_all(bmds->bs, bmds->blocker);
 604         error_free(bmds->blocker);
 605         bdrv_unref(bmds->bs);
 606         g_free(bmds->aio_bitmap);
 607         g_free(bmds);
 608     }
 609
 610     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 611         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 612         g_free(blk->buf);
 613         g_free(blk);
 614     }
 615     blk_mig_unlock();
 616 }
 617
 618 static void block_migration_cancel(void *opaque)
 619 {
 620     blk_mig_cleanup();
 621 }
 622
 623 static int block_save_setup(QEMUFile *f, void *opaque)
 624 {
 625     int ret;
 626
 627     DPRINTF("Enter save live setup submitted %d transferred %d\n",
 628             block_mig_state.submitted, block_mig_state.transferred);
 629
 630     qemu_mutex_lock_iothread();
 631     init_blk_migration(f);
 632
 633     /* start track dirty blocks */
 634     ret = set_dirty_tracking();
 635
 636     if (ret) {
 637         qemu_mutex_unlock_iothread();
 638         return ret;
 639     }
 640
 641     qemu_mutex_unlock_iothread();
 642
 643     ret = flush_blks(f);
 644     blk_mig_reset_dirty_cursor();
 645     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 646
 647     return ret;
 648 }
 649
 650 static int block_save_iterate(QEMUFile *f, void *opaque)
 651 {
 652     int ret;
 653     int64_t last_ftell = qemu_ftell(f);
 654
 655     DPRINTF("Enter save live iterate submitted %d transferred %d\n",
 656             block_mig_state.submitted, block_mig_state.transferred);
 657
 658     ret = flush_blks(f);
 659     if (ret) {
 660         return ret;
 661     }
 662
 663     blk_mig_reset_dirty_cursor();
 664
 665     /* control the rate of transfer */
 666     blk_mig_lock();
 667     while ((block_mig_state.submitted +
 668             block_mig_state.read_done) * BLOCK_SIZE <
 669            qemu_file_get_rate_limit(f)) {
 670         blk_mig_unlock();
 671         if (block_mig_state.bulk_completed == 0) {
 672             /* first finish the bulk phase */
 673             if (blk_mig_save_bulked_block(f) == 0) {
 674                 /* finished saving bulk on all devices */
 675                 block_mig_state.bulk_completed = 1;
 676             }
 677             ret = 0;
 678         } else {
 679             /* Always called with iothread lock taken for
 680              * simplicity, block_save_complete also calls it.
 681              */
 682             qemu_mutex_lock_iothread();
 683             ret = blk_mig_save_dirty_block(f, 1);
 684             qemu_mutex_unlock_iothread();
 685         }
 686         if (ret < 0) {
 687             return ret;
 688         }
 689         blk_mig_lock();
 690         if (ret != 0) {
 691             /* no more dirty blocks */
 692             break;
 693         }
 694     }
 695     blk_mig_unlock();
 696
 697     ret = flush_blks(f);
 698     if (ret) {
 699         return ret;
 700     }
 701
 702     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 703     return qemu_ftell(f) - last_ftell;
 704 }
 705
 706 /* Called with iothread lock taken.  */
 707
 708 static int block_save_complete(QEMUFile *f, void *opaque)
 709 {
 710     int ret;
 711
 712     DPRINTF("Enter save live complete submitted %d transferred %d\n",
 713             block_mig_state.submitted, block_mig_state.transferred);
 714
 715     ret = flush_blks(f);
 716     if (ret) {
 717         return ret;
 718     }
 719
 720     blk_mig_reset_dirty_cursor();
 721
 722     /* we know for sure that save bulk is completed and
 723        all async read completed */
 724     blk_mig_lock();
 725     assert(block_mig_state.submitted == 0);
 726     blk_mig_unlock();
 727
 728     do {
 729         ret = blk_mig_save_dirty_block(f, 0);
 730         if (ret < 0) {
 731             return ret;
 732         }
 733     } while (ret == 0);
 734
 735     /* report completion */
 736     qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 737
 738     DPRINTF("Block migration completed\n");
 739
 740     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 741
 742     blk_mig_cleanup();
 743     return 0;
 744 }
 745
 746 static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
 747 {
 748     /* Estimate pending number of bytes to send */
 749     uint64_t pending;
 750
 751     qemu_mutex_lock_iothread();
 752     blk_mig_lock();
 753     pending = get_remaining_dirty() +
 754                        block_mig_state.submitted * BLOCK_SIZE +
 755                        block_mig_state.read_done * BLOCK_SIZE;
 756
 757     /* Report at least one block pending during bulk phase */
 758     if (pending == 0 && !block_mig_state.bulk_completed) {
 759         pending = BLOCK_SIZE;
 760     }
 761     blk_mig_unlock();
 762     qemu_mutex_unlock_iothread();
 763
 764     DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
 765     return pending;
 766 }
 767
 768 static int block_load(QEMUFile *f, void *opaque, int version_id)
 769 {
 770     static int banner_printed;
 771     int len, flags;
 772     char device_name[256];
 773     int64_t addr;
 774     BlockDriverState *bs, *bs_prev = NULL;
 775     uint8_t *buf;
 776     int64_t total_sectors = 0;
 777     int nr_sectors;
 778     int ret;
 779
 780     do {
 781         addr = qemu_get_be64(f);
 782
 783         flags = addr & ~BDRV_SECTOR_MASK;
 784         addr >>= BDRV_SECTOR_BITS;
 785
 786         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 787             /* get device name */
 788             len = qemu_get_byte(f);
 789             qemu_get_buffer(f, (uint8_t *)device_name, len);
 790             device_name[len] = '\0';
 791
 792             bs = bdrv_find(device_name);
 793             if (!bs) {
 794                 fprintf(stderr, "Error unknown block device %s\n",
 795                         device_name);
 796                 return -EINVAL;
 797             }
 798
 799             if (bs != bs_prev) {
 800                 bs_prev = bs;
 801                 total_sectors = bdrv_nb_sectors(bs);
 802                 if (total_sectors <= 0) {
 803                     error_report("Error getting length of block device %s",
 804                                  device_name);
 805                     return -EINVAL;
 806                 }
 807             }
 808
 809             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 810                 nr_sectors = total_sectors - addr;
 811             } else {
 812                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 813             }
 814
 815             if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
 816                 ret = bdrv_write_zeroes(bs, addr, nr_sectors,
 817                                         BDRV_REQ_MAY_UNMAP);
 818             } else {
 819                 buf = g_malloc(BLOCK_SIZE);
 820                 qemu_get_buffer(f, buf, BLOCK_SIZE);
 821                 ret = bdrv_write(bs, addr, buf, nr_sectors);
 822                 g_free(buf);
 823             }
 824
 825             if (ret < 0) {
 826                 return ret;
 827             }
 828         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 829             if (!banner_printed) {
 830                 printf("Receiving block device images\n");
 831                 banner_printed = 1;
 832             }
 833             printf("Completed %d %%%c", (int)addr,
 834                    (addr == 100) ? '\n' : '\r');
 835             fflush(stdout);
 836         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 837             fprintf(stderr, "Unknown block migration flags: %#x\n", flags);
 838             return -EINVAL;
 839         }
 840         ret = qemu_file_get_error(f);
 841         if (ret != 0) {
 842             return ret;
 843         }
 844     } while (!(flags & BLK_MIG_FLAG_EOS));
 845
 846     return 0;
 847 }
 848
 849 static void block_set_params(const MigrationParams *params, void *opaque)
 850 {
 851     block_mig_state.blk_enable = params->blk;
 852     block_mig_state.shared_base = params->shared;
 853
 854     /* shared base means that blk_enable = 1 */
 855     block_mig_state.blk_enable |= params->shared;
 856 }
 857
 858 static bool block_is_active(void *opaque)
 859 {
 860     return block_mig_state.blk_enable == 1;
 861 }
 862
 863 static SaveVMHandlers savevm_block_handlers = {
 864     .set_params = block_set_params,
 865     .save_live_setup = block_save_setup,
 866     .save_live_iterate = block_save_iterate,
 867     .save_live_complete = block_save_complete,
 868     .save_live_pending = block_save_pending,
 869     .load_state = block_load,
 870     .cancel = block_migration_cancel,
 871     .is_active = block_is_active,
 872 };
 873
 874 void blk_mig_init(void)
 875 {
 876     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 877     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 878     qemu_mutex_init(&block_mig_state.lock);
 879
 880     register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
 881                          &block_mig_state);
 882 }