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