block-migration.c

   1 /*
   2  * QEMU live block migration
   3  *
   4  * Copyright IBM, Corp. 2009
   5  *
   6  * Authors:
   7  *  Liran Schour   <lirans@il.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "block_int.h"
  16 #include "hw/hw.h"
  17 #include "qemu-queue.h"
  18 #include "monitor.h"
  19 #include "block-migration.h"
  20 #include <assert.h>
  21
  22 #define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
  23
  24 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  25 #define BLK_MIG_FLAG_EOS                0x02
  26 #define BLK_MIG_FLAG_PROGRESS           0x04
  27
  28 #define MAX_IS_ALLOCATED_SEARCH 65536
  29 #define MAX_BLOCKS_READ 10000
  30 #define BLOCKS_READ_CHANGE 100
  31 #define INITIAL_BLOCKS_READ 100
  32
  33 //#define DEBUG_BLK_MIGRATION
  34
  35 #ifdef DEBUG_BLK_MIGRATION
  36 #define dprintf(fmt, ...) \
  37     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  38 #else
  39 #define dprintf(fmt, ...) \
  40     do { } while (0)
  41 #endif
  42
  43 typedef struct BlkMigDevState {
  44     BlockDriverState *bs;
  45     int bulk_completed;
  46     int shared_base;
  47     int64_t cur_sector;
  48     int64_t completed_sectors;
  49     int64_t total_sectors;
  50     int64_t dirty;
  51     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  52 } BlkMigDevState;
  53
  54 typedef struct BlkMigBlock {
  55     uint8_t *buf;
  56     BlkMigDevState *bmds;
  57     int64_t sector;
  58     struct iovec iov;
  59     QEMUIOVector qiov;
  60     BlockDriverAIOCB *aiocb;
  61     int ret;
  62     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  63 } BlkMigBlock;
  64
  65 typedef struct BlkMigState {
  66     int blk_enable;
  67     int shared_base;
  68     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  69     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  70     int submitted;
  71     int read_done;
  72     int transferred;
  73     int64_t total_sector_sum;
  74     int prev_progress;
  75 } BlkMigState;
  76
  77 static BlkMigState block_mig_state;
  78
  79 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
  80 {
  81     int len;
  82
  83     /* sector number and flags */
  84     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
  85                      | BLK_MIG_FLAG_DEVICE_BLOCK);
  86
  87     /* device name */
  88     len = strlen(blk->bmds->bs->device_name);
  89     qemu_put_byte(f, len);
  90     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
  91
  92     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
  93 }
  94
  95 int blk_mig_active(void)
  96 {
  97     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
  98 }
  99
 100 uint64_t blk_mig_bytes_transferred(void)
 101 {
 102     BlkMigDevState *bmds;
 103     uint64_t sum = 0;
 104
 105     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 106         sum += bmds->completed_sectors;
 107     }
 108     return sum << BDRV_SECTOR_BITS;
 109 }
 110
 111 uint64_t blk_mig_bytes_remaining(void)
 112 {
 113     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 114 }
 115
 116 uint64_t blk_mig_bytes_total(void)
 117 {
 118     BlkMigDevState *bmds;
 119     uint64_t sum = 0;
 120
 121     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 122         sum += bmds->total_sectors;
 123     }
 124     return sum << BDRV_SECTOR_BITS;
 125 }
 126
 127 static void blk_mig_read_cb(void *opaque, int ret)
 128 {
 129     BlkMigBlock *blk = opaque;
 130
 131     blk->ret = ret;
 132
 133     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 134
 135     block_mig_state.submitted--;
 136     block_mig_state.read_done++;
 137     assert(block_mig_state.submitted >= 0);
 138 }
 139
 140 static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
 141                                 BlkMigDevState *bmds, int is_async)
 142 {
 143     int64_t total_sectors = bmds->total_sectors;
 144     int64_t cur_sector = bmds->cur_sector;
 145     BlockDriverState *bs = bmds->bs;
 146     BlkMigBlock *blk;
 147     int nr_sectors;
 148
 149     if (bmds->shared_base) {
 150         while (cur_sector < total_sectors &&
 151                !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
 152                                   &nr_sectors)) {
 153             cur_sector += nr_sectors;
 154         }
 155     }
 156
 157     if (cur_sector >= total_sectors) {
 158         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 159         return 1;
 160     }
 161
 162     bmds->completed_sectors = cur_sector;
 163
 164     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 165
 166     /* we are going to transfer a full block even if it is not allocated */
 167     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 168
 169     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 170         nr_sectors = total_sectors - cur_sector;
 171     }
 172
 173     blk = qemu_malloc(sizeof(BlkMigBlock));
 174     blk->buf = qemu_malloc(BLOCK_SIZE);
 175     blk->bmds = bmds;
 176     blk->sector = cur_sector;
 177
 178     if (is_async) {
 179         blk->iov.iov_base = blk->buf;
 180         blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 181         qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 182
 183         blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
 184                                     nr_sectors, blk_mig_read_cb, blk);
 185         if (!blk->aiocb) {
 186             goto error;
 187         }
 188         block_mig_state.submitted++;
 189     } else {
 190         if (bdrv_read(bs, cur_sector, blk->buf, nr_sectors) < 0) {
 191             goto error;
 192         }
 193         blk_send(f, blk);
 194
 195         qemu_free(blk->buf);
 196         qemu_free(blk);
 197     }
 198
 199     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
 200     bmds->cur_sector = cur_sector + nr_sectors;
 201
 202     return (bmds->cur_sector >= total_sectors);
 203
 204 error:
 205     monitor_printf(mon, "Error reading sector %" PRId64 "\n", cur_sector);
 206     qemu_file_set_error(f);
 207     qemu_free(blk->buf);
 208     qemu_free(blk);
 209     return 0;
 210 }
 211
 212 static void set_dirty_tracking(int enable)
 213 {
 214     BlkMigDevState *bmds;
 215
 216     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 217         bdrv_set_dirty_tracking(bmds->bs, enable);
 218     }
 219 }
 220
 221 static void init_blk_migration(Monitor *mon, QEMUFile *f)
 222 {
 223     BlkMigDevState *bmds;
 224     BlockDriverState *bs;
 225     int64_t sectors;
 226
 227     block_mig_state.submitted = 0;
 228     block_mig_state.read_done = 0;
 229     block_mig_state.transferred = 0;
 230     block_mig_state.total_sector_sum = 0;
 231     block_mig_state.prev_progress = -1;
 232
 233     for (bs = bdrv_first; bs != NULL; bs = bs->next) {
 234         if (bs->type == BDRV_TYPE_HD) {
 235             sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 236             if (sectors == 0) {
 237                 continue;
 238             }
 239
 240             bmds = qemu_mallocz(sizeof(BlkMigDevState));
 241             bmds->bs = bs;
 242             bmds->bulk_completed = 0;
 243             bmds->total_sectors = sectors;
 244             bmds->completed_sectors = 0;
 245             bmds->shared_base = block_mig_state.shared_base;
 246
 247             block_mig_state.total_sector_sum += sectors;
 248
 249             if (bmds->shared_base) {
 250                 monitor_printf(mon, "Start migration for %s with shared base "
 251                                     "image\n",
 252                                bs->device_name);
 253             } else {
 254                 monitor_printf(mon, "Start full migration for %s\n",
 255                                bs->device_name);
 256             }
 257
 258             QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 259         }
 260     }
 261 }
 262
 263 static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f, int is_async)
 264 {
 265     int64_t completed_sector_sum = 0;
 266     BlkMigDevState *bmds;
 267     int progress;
 268     int ret = 0;
 269
 270     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 271         if (bmds->bulk_completed == 0) {
 272             if (mig_save_device_bulk(mon, f, bmds, is_async) == 1) {
 273                 /* completed bulk section for this device */
 274                 bmds->bulk_completed = 1;
 275             }
 276             completed_sector_sum += bmds->completed_sectors;
 277             ret = 1;
 278             break;
 279         } else {
 280             completed_sector_sum += bmds->completed_sectors;
 281         }
 282     }
 283
 284     progress = completed_sector_sum * 100 / block_mig_state.total_sector_sum;
 285     if (progress != block_mig_state.prev_progress) {
 286         block_mig_state.prev_progress = progress;
 287         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 288                          | BLK_MIG_FLAG_PROGRESS);
 289         monitor_printf(mon, "Completed %d %%\r", progress);
 290         monitor_flush(mon);
 291     }
 292
 293     return ret;
 294 }
 295
 296 #define MAX_NUM_BLOCKS 4
 297
 298 static void blk_mig_save_dirty_blocks(Monitor *mon, QEMUFile *f)
 299 {
 300     BlkMigDevState *bmds;
 301     BlkMigBlock blk;
 302     int64_t sector;
 303
 304     blk.buf = qemu_malloc(BLOCK_SIZE);
 305
 306     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 307         for (sector = 0; sector < bmds->cur_sector;) {
 308             if (bdrv_get_dirty(bmds->bs, sector)) {
 309                 if (bdrv_read(bmds->bs, sector, blk.buf,
 310                               BDRV_SECTORS_PER_DIRTY_CHUNK) < 0) {
 311                     monitor_printf(mon, "Error reading sector %" PRId64 "\n",
 312                                    sector);
 313                     qemu_file_set_error(f);
 314                     qemu_free(blk.buf);
 315                     return;
 316                 }
 317                 blk.bmds = bmds;
 318                 blk.sector = sector;
 319                 blk_send(f, &blk);
 320
 321                 bdrv_reset_dirty(bmds->bs, sector,
 322                                  BDRV_SECTORS_PER_DIRTY_CHUNK);
 323             }
 324             sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 325         }
 326     }
 327
 328     qemu_free(blk.buf);
 329 }
 330
 331 static void flush_blks(QEMUFile* f)
 332 {
 333     BlkMigBlock *blk;
 334
 335     dprintf("%s Enter submitted %d read_done %d transferred %d\n",
 336             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 337             block_mig_state.transferred);
 338
 339     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 340         if (qemu_file_rate_limit(f)) {
 341             break;
 342         }
 343         if (blk->ret < 0) {
 344             qemu_file_set_error(f);
 345             break;
 346         }
 347         blk_send(f, blk);
 348
 349         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 350         qemu_free(blk->buf);
 351         qemu_free(blk);
 352
 353         block_mig_state.read_done--;
 354         block_mig_state.transferred++;
 355         assert(block_mig_state.read_done >= 0);
 356     }
 357
 358     dprintf("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 359             block_mig_state.submitted, block_mig_state.read_done,
 360             block_mig_state.transferred);
 361 }
 362
 363 static int is_stage2_completed(void)
 364 {
 365     BlkMigDevState *bmds;
 366
 367     if (block_mig_state.submitted > 0) {
 368         return 0;
 369     }
 370
 371     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 372         if (bmds->bulk_completed == 0) {
 373             return 0;
 374         }
 375     }
 376
 377     return 1;
 378 }
 379
 380 static void blk_mig_cleanup(Monitor *mon)
 381 {
 382     BlkMigDevState *bmds;
 383     BlkMigBlock *blk;
 384
 385     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 386         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 387         qemu_free(bmds);
 388     }
 389
 390     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 391         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 392         qemu_free(blk->buf);
 393         qemu_free(blk);
 394     }
 395
 396     set_dirty_tracking(0);
 397
 398     monitor_printf(mon, "\n");
 399 }
 400
 401 static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 402 {
 403     dprintf("Enter save live stage %d submitted %d transferred %d\n",
 404             stage, block_mig_state.submitted, block_mig_state.transferred);
 405
 406     if (stage < 0) {
 407         blk_mig_cleanup(mon);
 408         return 0;
 409     }
 410
 411     if (block_mig_state.blk_enable != 1) {
 412         /* no need to migrate storage */
 413         qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 414         return 1;
 415     }
 416
 417     if (stage == 1) {
 418         init_blk_migration(mon, f);
 419
 420         /* start track dirty blocks */
 421         set_dirty_tracking(1);
 422     }
 423
 424     flush_blks(f);
 425
 426     if (qemu_file_has_error(f)) {
 427         blk_mig_cleanup(mon);
 428         return 0;
 429     }
 430
 431     /* control the rate of transfer */
 432     while ((block_mig_state.submitted +
 433             block_mig_state.read_done) * BLOCK_SIZE <
 434            qemu_file_get_rate_limit(f)) {
 435         if (blk_mig_save_bulked_block(mon, f, 1) == 0) {
 436             /* no more bulk blocks for now */
 437             break;
 438         }
 439     }
 440
 441     flush_blks(f);
 442
 443     if (qemu_file_has_error(f)) {
 444         blk_mig_cleanup(mon);
 445         return 0;
 446     }
 447
 448     if (stage == 3) {
 449         while (blk_mig_save_bulked_block(mon, f, 0) != 0) {
 450             /* empty */
 451         }
 452
 453         blk_mig_save_dirty_blocks(mon, f);
 454         blk_mig_cleanup(mon);
 455
 456         /* report completion */
 457         qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 458
 459         if (qemu_file_has_error(f)) {
 460             return 0;
 461         }
 462
 463         monitor_printf(mon, "Block migration completed\n");
 464     }
 465
 466     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 467
 468     return ((stage == 2) && is_stage2_completed());
 469 }
 470
 471 static int block_load(QEMUFile *f, void *opaque, int version_id)
 472 {
 473     static int banner_printed;
 474     int len, flags;
 475     char device_name[256];
 476     int64_t addr;
 477     BlockDriverState *bs;
 478     uint8_t *buf;
 479
 480     do {
 481         addr = qemu_get_be64(f);
 482
 483         flags = addr & ~BDRV_SECTOR_MASK;
 484         addr >>= BDRV_SECTOR_BITS;
 485
 486         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 487             /* get device name */
 488             len = qemu_get_byte(f);
 489             qemu_get_buffer(f, (uint8_t *)device_name, len);
 490             device_name[len] = '\0';
 491
 492             bs = bdrv_find(device_name);
 493             if (!bs) {
 494                 fprintf(stderr, "Error unknown block device %s\n",
 495                         device_name);
 496                 return -EINVAL;
 497             }
 498
 499             buf = qemu_malloc(BLOCK_SIZE);
 500
 501             qemu_get_buffer(f, buf, BLOCK_SIZE);
 502             bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);
 503
 504             qemu_free(buf);
 505         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 506             if (!banner_printed) {
 507                 printf("Receiving block device images\n");
 508                 banner_printed = 1;
 509             }
 510             printf("Completed %d %%%c", (int)addr,
 511                    (addr == 100) ? '\n' : '\r');
 512             fflush(stdout);
 513         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 514             fprintf(stderr, "Unknown flags\n");
 515             return -EINVAL;
 516         }
 517         if (qemu_file_has_error(f)) {
 518             return -EIO;
 519         }
 520     } while (!(flags & BLK_MIG_FLAG_EOS));
 521
 522     return 0;
 523 }
 524
 525 static void block_set_params(int blk_enable, int shared_base, void *opaque)
 526 {
 527     block_mig_state.blk_enable = blk_enable;
 528     block_mig_state.shared_base = shared_base;
 529
 530     /* shared base means that blk_enable = 1 */
 531     block_mig_state.blk_enable |= shared_base;
 532 }
 533
 534 void blk_mig_init(void)
 535 {
 536     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 537     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 538
 539     register_savevm_live("block", 0, 1, block_set_params, block_save_live,
 540                          NULL, block_load, &block_mig_state);
 541 }