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 * 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/osdep.h"
17 #include "qapi/error.h"
18 #include "qemu/error-report.h"
19 #include "qemu/cutils.h"
20 #include "qemu/queue.h"
21 #include "block.h"
22 #include "migration/misc.h"
23 #include "migration.h"
24 #include "migration/register.h"
25 #include "qemu-file.h"
26 #include "migration/vmstate.h"
27 #include "sysemu/block-backend.h"
28
29 #define BLOCK_SIZE (1 << 20)
30 #define BDRV_SECTORS_PER_DIRTY_CHUNK (BLOCK_SIZE >> BDRV_SECTOR_BITS)
31
32 #define BLK_MIG_FLAG_DEVICE_BLOCK 0x01
33 #define BLK_MIG_FLAG_EOS 0x02
34 #define BLK_MIG_FLAG_PROGRESS 0x04
35 #define BLK_MIG_FLAG_ZERO_BLOCK 0x08
36
37 #define MAX_IS_ALLOCATED_SEARCH (65536 * BDRV_SECTOR_SIZE)
38
39 #define MAX_IO_BUFFERS 512
40 #define MAX_PARALLEL_IO 16
41
42 //#define DEBUG_BLK_MIGRATION
43
44 #ifdef DEBUG_BLK_MIGRATION
45 #define DPRINTF(fmt, ...) \
46 do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
47 #else
48 #define DPRINTF(fmt, ...) \
49 do { } while (0)
50 #endif
51
52 typedef struct BlkMigDevState {
53 /* Written during setup phase. Can be read without a lock. */
54 BlockBackend *blk;
55 char *blk_name;
56 int shared_base;
57 int64_t total_sectors;
58 QSIMPLEQ_ENTRY(BlkMigDevState) entry;
59 Error *blocker;
60
61 /* Only used by migration thread. Does not need a lock. */
62 int bulk_completed;
63 int64_t cur_sector;
64 int64_t cur_dirty;
65
66 /* Data in the aio_bitmap is protected by block migration lock.
67 * Allocation and free happen during setup and cleanup respectively.
68 */
69 unsigned long *aio_bitmap;
70
71 /* Protected by block migration lock. */
72 int64_t completed_sectors;
73
74 /* During migration this is protected by iothread lock / AioContext.
75 * Allocation and free happen during setup and cleanup respectively.
76 */
77 BdrvDirtyBitmap *dirty_bitmap;
78 } BlkMigDevState;
79
80 typedef struct BlkMigBlock {
81 /* Only used by migration thread. */
82 uint8_t *buf;
83 BlkMigDevState *bmds;
84 int64_t sector;
85 int nr_sectors;
86 struct iovec iov;
87 QEMUIOVector qiov;
88 BlockAIOCB *aiocb;
89
90 /* Protected by block migration lock. */
91 int ret;
92 QSIMPLEQ_ENTRY(BlkMigBlock) entry;
93 } BlkMigBlock;
94
95 typedef struct BlkMigState {
96 QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
97 int64_t total_sector_sum;
98 bool zero_blocks;
99
100 /* Protected by lock. */
101 QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
102 int submitted;
103 int read_done;
104
105 /* Only used by migration thread. Does not need a lock. */
106 int transferred;
107 int prev_progress;
108 int bulk_completed;
109
110 /* Lock must be taken _inside_ the iothread lock and any AioContexts. */
111 QemuMutex lock;
112 } BlkMigState;
113
114 static BlkMigState block_mig_state;
115
blk_mig_lock(void)116 static void blk_mig_lock(void)
117 {
118 qemu_mutex_lock(&block_mig_state.lock);
119 }
120
blk_mig_unlock(void)121 static void blk_mig_unlock(void)
122 {
123 qemu_mutex_unlock(&block_mig_state.lock);
124 }
125
126 /* Must run outside of the iothread lock during the bulk phase,
127 * or the VM will stall.
128 */
129
blk_send(QEMUFile * f,BlkMigBlock * blk)130 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
131 {
132 int len;
133 uint64_t flags = BLK_MIG_FLAG_DEVICE_BLOCK;
134
135 if (block_mig_state.zero_blocks &&
136 buffer_is_zero(blk->buf, BLOCK_SIZE)) {
137 flags |= BLK_MIG_FLAG_ZERO_BLOCK;
138 }
139
140 /* sector number and flags */
141 qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
142 | flags);
143
144 /* device name */
145 len = strlen(blk->bmds->blk_name);
146 qemu_put_byte(f, len);
147 qemu_put_buffer(f, (uint8_t *) blk->bmds->blk_name, len);
148
149 /* if a block is zero we need to flush here since the network
150 * bandwidth is now a lot higher than the storage device bandwidth.
151 * thus if we queue zero blocks we slow down the migration */
152 if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
153 qemu_fflush(f);
154 return;
155 }
156
157 qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
158 }
159
blk_mig_active(void)160 int blk_mig_active(void)
161 {
162 return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
163 }
164
blk_mig_bulk_active(void)165 int blk_mig_bulk_active(void)
166 {
167 return blk_mig_active() && !block_mig_state.bulk_completed;
168 }
169
blk_mig_bytes_transferred(void)170 uint64_t blk_mig_bytes_transferred(void)
171 {
172 BlkMigDevState *bmds;
173 uint64_t sum = 0;
174
175 blk_mig_lock();
176 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
177 sum += bmds->completed_sectors;
178 }
179 blk_mig_unlock();
180 return sum << BDRV_SECTOR_BITS;
181 }
182
blk_mig_bytes_remaining(void)183 uint64_t blk_mig_bytes_remaining(void)
184 {
185 return blk_mig_bytes_total() - blk_mig_bytes_transferred();
186 }
187
blk_mig_bytes_total(void)188 uint64_t blk_mig_bytes_total(void)
189 {
190 BlkMigDevState *bmds;
191 uint64_t sum = 0;
192
193 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
194 sum += bmds->total_sectors;
195 }
196 return sum << BDRV_SECTOR_BITS;
197 }
198
199
200 /* Called with migration lock held. */
201
bmds_aio_inflight(BlkMigDevState * bmds,int64_t sector)202 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
203 {
204 int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
205
206 if (sector < blk_nb_sectors(bmds->blk)) {
207 return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
208 (1UL << (chunk % (sizeof(unsigned long) * 8))));
209 } else {
210 return 0;
211 }
212 }
213
214 /* Called with migration lock held. */
215
bmds_set_aio_inflight(BlkMigDevState * bmds,int64_t sector_num,int nb_sectors,int set)216 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
217 int nb_sectors, int set)
218 {
219 int64_t start, end;
220 unsigned long val, idx, bit;
221
222 start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
223 end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
224
225 for (; start <= end; start++) {
226 idx = start / (sizeof(unsigned long) * 8);
227 bit = start % (sizeof(unsigned long) * 8);
228 val = bmds->aio_bitmap[idx];
229 if (set) {
230 val |= 1UL << bit;
231 } else {
232 val &= ~(1UL << bit);
233 }
234 bmds->aio_bitmap[idx] = val;
235 }
236 }
237
alloc_aio_bitmap(BlkMigDevState * bmds)238 static void alloc_aio_bitmap(BlkMigDevState *bmds)
239 {
240 BlockBackend *bb = bmds->blk;
241 int64_t bitmap_size;
242
243 bitmap_size = blk_nb_sectors(bb) + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
244 bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
245
246 bmds->aio_bitmap = g_malloc0(bitmap_size);
247 }
248
249 /* Never hold migration lock when yielding to the main loop! */
250
blk_mig_read_cb(void * opaque,int ret)251 static void blk_mig_read_cb(void *opaque, int ret)
252 {
253 BlkMigBlock *blk = opaque;
254
255 blk_mig_lock();
256 blk->ret = ret;
257
258 QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
259 bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
260
261 block_mig_state.submitted--;
262 block_mig_state.read_done++;
263 assert(block_mig_state.submitted >= 0);
264 blk_mig_unlock();
265 }
266
267 /* Called with no lock taken. */
268
mig_save_device_bulk(QEMUFile * f,BlkMigDevState * bmds)269 static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
270 {
271 int64_t total_sectors = bmds->total_sectors;
272 int64_t cur_sector = bmds->cur_sector;
273 BlockBackend *bb = bmds->blk;
274 BlkMigBlock *blk;
275 int nr_sectors;
276 int64_t count;
277
278 if (bmds->shared_base) {
279 qemu_mutex_lock_iothread();
280 aio_context_acquire(blk_get_aio_context(bb));
281 /* Skip unallocated sectors; intentionally treats failure or
282 * partial sector as an allocated sector */
283 while (cur_sector < total_sectors &&
284 !bdrv_is_allocated(blk_bs(bb), cur_sector * BDRV_SECTOR_SIZE,
285 MAX_IS_ALLOCATED_SEARCH, &count)) {
286 if (count < BDRV_SECTOR_SIZE) {
287 break;
288 }
289 cur_sector += count >> BDRV_SECTOR_BITS;
290 }
291 aio_context_release(blk_get_aio_context(bb));
292 qemu_mutex_unlock_iothread();
293 }
294
295 if (cur_sector >= total_sectors) {
296 bmds->cur_sector = bmds->completed_sectors = total_sectors;
297 return 1;
298 }
299
300 bmds->completed_sectors = cur_sector;
301
302 cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
303
304 /* we are going to transfer a full block even if it is not allocated */
305 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
306
307 if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
308 nr_sectors = total_sectors - cur_sector;
309 }
310
311 blk = g_new(BlkMigBlock, 1);
312 blk->buf = g_malloc(BLOCK_SIZE);
313 blk->bmds = bmds;
314 blk->sector = cur_sector;
315 blk->nr_sectors = nr_sectors;
316
317 blk->iov.iov_base = blk->buf;
318 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
319 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
320
321 blk_mig_lock();
322 block_mig_state.submitted++;
323 blk_mig_unlock();
324
325 /* We do not know if bs is under the main thread (and thus does
326 * not acquire the AioContext when doing AIO) or rather under
327 * dataplane. Thus acquire both the iothread mutex and the
328 * AioContext.
329 *
330 * This is ugly and will disappear when we make bdrv_* thread-safe,
331 * without the need to acquire the AioContext.
332 */
333 qemu_mutex_lock_iothread();
334 aio_context_acquire(blk_get_aio_context(bmds->blk));
335 bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, cur_sector * BDRV_SECTOR_SIZE,
336 nr_sectors * BDRV_SECTOR_SIZE);
337 blk->aiocb = blk_aio_preadv(bb, cur_sector * BDRV_SECTOR_SIZE, &blk->qiov,
338 0, blk_mig_read_cb, blk);
339 aio_context_release(blk_get_aio_context(bmds->blk));
340 qemu_mutex_unlock_iothread();
341
342 bmds->cur_sector = cur_sector + nr_sectors;
343 return (bmds->cur_sector >= total_sectors);
344 }
345
346 /* Called with iothread lock taken. */
347
set_dirty_tracking(void)348 static int set_dirty_tracking(void)
349 {
350 BlkMigDevState *bmds;
351 int ret;
352
353 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
354 bmds->dirty_bitmap = bdrv_create_dirty_bitmap(blk_bs(bmds->blk),
355 BLOCK_SIZE, NULL, NULL);
356 if (!bmds->dirty_bitmap) {
357 ret = -errno;
358 goto fail;
359 }
360 }
361 return 0;
362
363 fail:
364 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
365 if (bmds->dirty_bitmap) {
366 bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);
367 }
368 }
369 return ret;
370 }
371
372 /* Called with iothread lock taken. */
373
unset_dirty_tracking(void)374 static void unset_dirty_tracking(void)
375 {
376 BlkMigDevState *bmds;
377
378 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
379 bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);
380 }
381 }
382
init_blk_migration(QEMUFile * f)383 static int init_blk_migration(QEMUFile *f)
384 {
385 BlockDriverState *bs;
386 BlkMigDevState *bmds;
387 int64_t sectors;
388 BdrvNextIterator it;
389 int i, num_bs = 0;
390 struct {
391 BlkMigDevState *bmds;
392 BlockDriverState *bs;
393 } *bmds_bs;
394 Error *local_err = NULL;
395 int ret;
396
397 block_mig_state.submitted = 0;
398 block_mig_state.read_done = 0;
399 block_mig_state.transferred = 0;
400 block_mig_state.total_sector_sum = 0;
401 block_mig_state.prev_progress = -1;
402 block_mig_state.bulk_completed = 0;
403 block_mig_state.zero_blocks = migrate_zero_blocks();
404
405 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
406 num_bs++;
407 }
408 bmds_bs = g_malloc0(num_bs * sizeof(*bmds_bs));
409
410 for (i = 0, bs = bdrv_first(&it); bs; bs = bdrv_next(&it), i++) {
411 if (bdrv_is_read_only(bs)) {
412 continue;
413 }
414
415 sectors = bdrv_nb_sectors(bs);
416 if (sectors <= 0) {
417 ret = sectors;
418 bdrv_next_cleanup(&it);
419 goto out;
420 }
421
422 bmds = g_new0(BlkMigDevState, 1);
423 bmds->blk = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
424 bmds->blk_name = g_strdup(bdrv_get_device_name(bs));
425 bmds->bulk_completed = 0;
426 bmds->total_sectors = sectors;
427 bmds->completed_sectors = 0;
428 bmds->shared_base = migrate_use_block_incremental();
429
430 assert(i < num_bs);
431 bmds_bs[i].bmds = bmds;
432 bmds_bs[i].bs = bs;
433
434 block_mig_state.total_sector_sum += sectors;
435
436 if (bmds->shared_base) {
437 DPRINTF("Start migration for %s with shared base image\n",
438 bdrv_get_device_name(bs));
439 } else {
440 DPRINTF("Start full migration for %s\n", bdrv_get_device_name(bs));
441 }
442
443 QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
444 }
445
446 /* Can only insert new BDSes now because doing so while iterating block
447 * devices may end up in a deadlock (iterating the new BDSes, too). */
448 for (i = 0; i < num_bs; i++) {
449 BlkMigDevState *bmds = bmds_bs[i].bmds;
450 BlockDriverState *bs = bmds_bs[i].bs;
451
452 if (bmds) {
453 ret = blk_insert_bs(bmds->blk, bs, &local_err);
454 if (ret < 0) {
455 error_report_err(local_err);
456 goto out;
457 }
458
459 alloc_aio_bitmap(bmds);
460 error_setg(&bmds->blocker, "block device is in use by migration");
461 bdrv_op_block_all(bs, bmds->blocker);
462 }
463 }
464
465 ret = 0;
466 out:
467 g_free(bmds_bs);
468 return ret;
469 }
470
471 /* Called with no lock taken. */
472
blk_mig_save_bulked_block(QEMUFile * f)473 static int blk_mig_save_bulked_block(QEMUFile *f)
474 {
475 int64_t completed_sector_sum = 0;
476 BlkMigDevState *bmds;
477 int progress;
478 int ret = 0;
479
480 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
481 if (bmds->bulk_completed == 0) {
482 if (mig_save_device_bulk(f, bmds) == 1) {
483 /* completed bulk section for this device */
484 bmds->bulk_completed = 1;
485 }
486 completed_sector_sum += bmds->completed_sectors;
487 ret = 1;
488 break;
489 } else {
490 completed_sector_sum += bmds->completed_sectors;
491 }
492 }
493
494 if (block_mig_state.total_sector_sum != 0) {
495 progress = completed_sector_sum * 100 /
496 block_mig_state.total_sector_sum;
497 } else {
498 progress = 100;
499 }
500 if (progress != block_mig_state.prev_progress) {
501 block_mig_state.prev_progress = progress;
502 qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
503 | BLK_MIG_FLAG_PROGRESS);
504 DPRINTF("Completed %d %%\r", progress);
505 }
506
507 return ret;
508 }
509
blk_mig_reset_dirty_cursor(void)510 static void blk_mig_reset_dirty_cursor(void)
511 {
512 BlkMigDevState *bmds;
513
514 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
515 bmds->cur_dirty = 0;
516 }
517 }
518
519 /* Called with iothread lock and AioContext taken. */
520
mig_save_device_dirty(QEMUFile * f,BlkMigDevState * bmds,int is_async)521 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
522 int is_async)
523 {
524 BlkMigBlock *blk;
525 BlockDriverState *bs = blk_bs(bmds->blk);
526 int64_t total_sectors = bmds->total_sectors;
527 int64_t sector;
528 int nr_sectors;
529 int ret = -EIO;
530
531 for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
532 blk_mig_lock();
533 if (bmds_aio_inflight(bmds, sector)) {
534 blk_mig_unlock();
535 blk_drain(bmds->blk);
536 } else {
537 blk_mig_unlock();
538 }
539 bdrv_dirty_bitmap_lock(bmds->dirty_bitmap);
540 if (bdrv_get_dirty_locked(bs, bmds->dirty_bitmap,
541 sector * BDRV_SECTOR_SIZE)) {
542 if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
543 nr_sectors = total_sectors - sector;
544 } else {
545 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
546 }
547 bdrv_reset_dirty_bitmap_locked(bmds->dirty_bitmap,
548 sector * BDRV_SECTOR_SIZE,
549 nr_sectors * BDRV_SECTOR_SIZE);
550 bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
551
552 blk = g_new(BlkMigBlock, 1);
553 blk->buf = g_malloc(BLOCK_SIZE);
554 blk->bmds = bmds;
555 blk->sector = sector;
556 blk->nr_sectors = nr_sectors;
557
558 if (is_async) {
559 blk->iov.iov_base = blk->buf;
560 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
561 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
562
563 blk->aiocb = blk_aio_preadv(bmds->blk,
564 sector * BDRV_SECTOR_SIZE,
565 &blk->qiov, 0, blk_mig_read_cb,
566 blk);
567
568 blk_mig_lock();
569 block_mig_state.submitted++;
570 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
571 blk_mig_unlock();
572 } else {
573 ret = blk_pread(bmds->blk, sector * BDRV_SECTOR_SIZE, blk->buf,
574 nr_sectors * BDRV_SECTOR_SIZE);
575 if (ret < 0) {
576 goto error;
577 }
578 blk_send(f, blk);
579
580 g_free(blk->buf);
581 g_free(blk);
582 }
583
584 sector += nr_sectors;
585 bmds->cur_dirty = sector;
586 break;
587 }
588
589 bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
590 sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
591 bmds->cur_dirty = sector;
592 }
593
594 return (bmds->cur_dirty >= bmds->total_sectors);
595
596 error:
597 DPRINTF("Error reading sector %" PRId64 "\n", sector);
598 g_free(blk->buf);
599 g_free(blk);
600 return ret;
601 }
602
603 /* Called with iothread lock taken.
604 *
605 * return value:
606 * 0: too much data for max_downtime
607 * 1: few enough data for max_downtime
608 */
blk_mig_save_dirty_block(QEMUFile * f,int is_async)609 static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
610 {
611 BlkMigDevState *bmds;
612 int ret = 1;
613
614 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
615 aio_context_acquire(blk_get_aio_context(bmds->blk));
616 ret = mig_save_device_dirty(f, bmds, is_async);
617 aio_context_release(blk_get_aio_context(bmds->blk));
618 if (ret <= 0) {
619 break;
620 }
621 }
622
623 return ret;
624 }
625
626 /* Called with no locks taken. */
627
flush_blks(QEMUFile * f)628 static int flush_blks(QEMUFile *f)
629 {
630 BlkMigBlock *blk;
631 int ret = 0;
632
633 DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
634 __func__, block_mig_state.submitted, block_mig_state.read_done,
635 block_mig_state.transferred);
636
637 blk_mig_lock();
638 while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
639 if (qemu_file_rate_limit(f)) {
640 break;
641 }
642 if (blk->ret < 0) {
643 ret = blk->ret;
644 break;
645 }
646
647 QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
648 blk_mig_unlock();
649 blk_send(f, blk);
650 blk_mig_lock();
651
652 g_free(blk->buf);
653 g_free(blk);
654
655 block_mig_state.read_done--;
656 block_mig_state.transferred++;
657 assert(block_mig_state.read_done >= 0);
658 }
659 blk_mig_unlock();
660
661 DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __func__,
662 block_mig_state.submitted, block_mig_state.read_done,
663 block_mig_state.transferred);
664 return ret;
665 }
666
667 /* Called with iothread lock taken. */
668
get_remaining_dirty(void)669 static int64_t get_remaining_dirty(void)
670 {
671 BlkMigDevState *bmds;
672 int64_t dirty = 0;
673
674 QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
675 aio_context_acquire(blk_get_aio_context(bmds->blk));
676 dirty += bdrv_get_dirty_count(bmds->dirty_bitmap);
677 aio_context_release(blk_get_aio_context(bmds->blk));
678 }
679
680 return dirty;
681 }
682
683
684
685 /* Called with iothread lock taken. */
block_migration_cleanup_bmds(void)686 static void block_migration_cleanup_bmds(void)
687 {
688 BlkMigDevState *bmds;
689 AioContext *ctx;
690
691 unset_dirty_tracking();
692
693 while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
694 QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
695 bdrv_op_unblock_all(blk_bs(bmds->blk), bmds->blocker);
696 error_free(bmds->blocker);
697
698 /* Save ctx, because bmds->blk can disappear during blk_unref. */
699 ctx = blk_get_aio_context(bmds->blk);
700 aio_context_acquire(ctx);
701 blk_unref(bmds->blk);
702 aio_context_release(ctx);
703
704 g_free(bmds->blk_name);
705 g_free(bmds->aio_bitmap);
706 g_free(bmds);
707 }
708 }
709
710 /* Called with iothread lock taken. */
block_migration_cleanup(void * opaque)711 static void block_migration_cleanup(void *opaque)
712 {
713 BlkMigBlock *blk;
714
715 bdrv_drain_all();
716
717 block_migration_cleanup_bmds();
718
719 blk_mig_lock();
720 while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
721 QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
722 g_free(blk->buf);
723 g_free(blk);
724 }
725 blk_mig_unlock();
726 }
727
block_save_setup(QEMUFile * f,void * opaque)728 static int block_save_setup(QEMUFile *f, void *opaque)
729 {
730 int ret;
731
732 DPRINTF("Enter save live setup submitted %d transferred %d\n",
733 block_mig_state.submitted, block_mig_state.transferred);
734
735 qemu_mutex_lock_iothread();
736 ret = init_blk_migration(f);
737 if (ret < 0) {
738 qemu_mutex_unlock_iothread();
739 return ret;
740 }
741
742 /* start track dirty blocks */
743 ret = set_dirty_tracking();
744
745 qemu_mutex_unlock_iothread();
746
747 if (ret) {
748 return ret;
749 }
750
751 ret = flush_blks(f);
752 blk_mig_reset_dirty_cursor();
753 qemu_put_be64(f, BLK_MIG_FLAG_EOS);
754
755 return ret;
756 }
757
block_save_iterate(QEMUFile * f,void * opaque)758 static int block_save_iterate(QEMUFile *f, void *opaque)
759 {
760 int ret;
761 int64_t last_ftell = qemu_ftell(f);
762 int64_t delta_ftell;
763
764 DPRINTF("Enter save live iterate submitted %d transferred %d\n",
765 block_mig_state.submitted, block_mig_state.transferred);
766
767 ret = flush_blks(f);
768 if (ret) {
769 return ret;
770 }
771
772 blk_mig_reset_dirty_cursor();
773
774 /* control the rate of transfer */
775 blk_mig_lock();
776 while (block_mig_state.read_done * BLOCK_SIZE <
777 qemu_file_get_rate_limit(f) &&
778 block_mig_state.submitted < MAX_PARALLEL_IO &&
779 (block_mig_state.submitted + block_mig_state.read_done) <
780 MAX_IO_BUFFERS) {
781 blk_mig_unlock();
782 if (block_mig_state.bulk_completed == 0) {
783 /* first finish the bulk phase */
784 if (blk_mig_save_bulked_block(f) == 0) {
785 /* finished saving bulk on all devices */
786 block_mig_state.bulk_completed = 1;
787 }
788 ret = 0;
789 } else {
790 /* Always called with iothread lock taken for
791 * simplicity, block_save_complete also calls it.
792 */
793 qemu_mutex_lock_iothread();
794 ret = blk_mig_save_dirty_block(f, 1);
795 qemu_mutex_unlock_iothread();
796 }
797 if (ret < 0) {
798 return ret;
799 }
800 blk_mig_lock();
801 if (ret != 0) {
802 /* no more dirty blocks */
803 break;
804 }
805 }
806 blk_mig_unlock();
807
808 ret = flush_blks(f);
809 if (ret) {
810 return ret;
811 }
812
813 qemu_put_be64(f, BLK_MIG_FLAG_EOS);
814 delta_ftell = qemu_ftell(f) - last_ftell;
815 if (delta_ftell > 0) {
816 return 1;
817 } else if (delta_ftell < 0) {
818 return -1;
819 } else {
820 return 0;
821 }
822 }
823
824 /* Called with iothread lock taken. */
825
block_save_complete(QEMUFile * f,void * opaque)826 static int block_save_complete(QEMUFile *f, void *opaque)
827 {
828 int ret;
829
830 DPRINTF("Enter save live complete submitted %d transferred %d\n",
831 block_mig_state.submitted, block_mig_state.transferred);
832
833 ret = flush_blks(f);
834 if (ret) {
835 return ret;
836 }
837
838 blk_mig_reset_dirty_cursor();
839
840 /* we know for sure that save bulk is completed and
841 all async read completed */
842 blk_mig_lock();
843 assert(block_mig_state.submitted == 0);
844 blk_mig_unlock();
845
846 do {
847 ret = blk_mig_save_dirty_block(f, 0);
848 if (ret < 0) {
849 return ret;
850 }
851 } while (ret == 0);
852
853 /* report completion */
854 qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
855
856 DPRINTF("Block migration completed\n");
857
858 qemu_put_be64(f, BLK_MIG_FLAG_EOS);
859
860 /* Make sure that our BlockBackends are gone, so that the block driver
861 * nodes can be inactivated. */
862 block_migration_cleanup_bmds();
863
864 return 0;
865 }
866
block_save_pending(QEMUFile * f,void * opaque,uint64_t max_size,uint64_t * res_precopy_only,uint64_t * res_compatible,uint64_t * res_postcopy_only)867 static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
868 uint64_t *res_precopy_only,
869 uint64_t *res_compatible,
870 uint64_t *res_postcopy_only)
871 {
872 /* Estimate pending number of bytes to send */
873 uint64_t pending;
874
875 qemu_mutex_lock_iothread();
876 pending = get_remaining_dirty();
877 qemu_mutex_unlock_iothread();
878
879 blk_mig_lock();
880 pending += block_mig_state.submitted * BLOCK_SIZE +
881 block_mig_state.read_done * BLOCK_SIZE;
882 blk_mig_unlock();
883
884 /* Report at least one block pending during bulk phase */
885 if (pending <= max_size && !block_mig_state.bulk_completed) {
886 pending = max_size + BLOCK_SIZE;
887 }
888
889 DPRINTF("Enter save live pending %" PRIu64 "\n", pending);
890 /* We don't do postcopy */
891 *res_precopy_only += pending;
892 }
893
block_load(QEMUFile * f,void * opaque,int version_id)894 static int block_load(QEMUFile *f, void *opaque, int version_id)
895 {
896 static int banner_printed;
897 int len, flags;
898 char device_name[256];
899 int64_t addr;
900 BlockBackend *blk, *blk_prev = NULL;
901 Error *local_err = NULL;
902 uint8_t *buf;
903 int64_t total_sectors = 0;
904 int nr_sectors;
905 int ret;
906 BlockDriverInfo bdi;
907 int cluster_size = BLOCK_SIZE;
908
909 do {
910 addr = qemu_get_be64(f);
911
912 flags = addr & ~BDRV_SECTOR_MASK;
913 addr >>= BDRV_SECTOR_BITS;
914
915 if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
916 /* get device name */
917 len = qemu_get_byte(f);
918 qemu_get_buffer(f, (uint8_t *)device_name, len);
919 device_name[len] = '\0';
920
921 blk = blk_by_name(device_name);
922 if (!blk) {
923 fprintf(stderr, "Error unknown block device %s\n",
924 device_name);
925 return -EINVAL;
926 }
927
928 if (blk != blk_prev) {
929 blk_prev = blk;
930 total_sectors = blk_nb_sectors(blk);
931 if (total_sectors <= 0) {
932 error_report("Error getting length of block device %s",
933 device_name);
934 return -EINVAL;
935 }
936
937 blk_invalidate_cache(blk, &local_err);
938 if (local_err) {
939 error_report_err(local_err);
940 return -EINVAL;
941 }
942
943 ret = bdrv_get_info(blk_bs(blk), &bdi);
944 if (ret == 0 && bdi.cluster_size > 0 &&
945 bdi.cluster_size <= BLOCK_SIZE &&
946 BLOCK_SIZE % bdi.cluster_size == 0) {
947 cluster_size = bdi.cluster_size;
948 } else {
949 cluster_size = BLOCK_SIZE;
950 }
951 }
952
953 if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
954 nr_sectors = total_sectors - addr;
955 } else {
956 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
957 }
958
959 if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
960 ret = blk_pwrite_zeroes(blk, addr * BDRV_SECTOR_SIZE,
961 nr_sectors * BDRV_SECTOR_SIZE,
962 BDRV_REQ_MAY_UNMAP);
963 } else {
964 int i;
965 int64_t cur_addr;
966 uint8_t *cur_buf;
967
968 buf = g_malloc(BLOCK_SIZE);
969 qemu_get_buffer(f, buf, BLOCK_SIZE);
970 for (i = 0; i < BLOCK_SIZE / cluster_size; i++) {
971 cur_addr = addr * BDRV_SECTOR_SIZE + i * cluster_size;
972 cur_buf = buf + i * cluster_size;
973
974 if ((!block_mig_state.zero_blocks ||
975 cluster_size < BLOCK_SIZE) &&
976 buffer_is_zero(cur_buf, cluster_size)) {
977 ret = blk_pwrite_zeroes(blk, cur_addr,
978 cluster_size,
979 BDRV_REQ_MAY_UNMAP);
980 } else {
981 ret = blk_pwrite(blk, cur_addr, cur_buf,
982 cluster_size, 0);
983 }
984 if (ret < 0) {
985 break;
986 }
987 }
988 g_free(buf);
989 }
990
991 if (ret < 0) {
992 return ret;
993 }
994 } else if (flags & BLK_MIG_FLAG_PROGRESS) {
995 if (!banner_printed) {
996 printf("Receiving block device images\n");
997 banner_printed = 1;
998 }
999 printf("Completed %d %%%c", (int)addr,
1000 (addr == 100) ? '\n' : '\r');
1001 fflush(stdout);
1002 } else if (!(flags & BLK_MIG_FLAG_EOS)) {
1003 fprintf(stderr, "Unknown block migration flags: %#x\n", flags);
1004 return -EINVAL;
1005 }
1006 ret = qemu_file_get_error(f);
1007 if (ret != 0) {
1008 return ret;
1009 }
1010 } while (!(flags & BLK_MIG_FLAG_EOS));
1011
1012 return 0;
1013 }
1014
block_is_active(void * opaque)1015 static bool block_is_active(void *opaque)
1016 {
1017 return migrate_use_block();
1018 }
1019
1020 static SaveVMHandlers savevm_block_handlers = {
1021 .save_setup = block_save_setup,
1022 .save_live_iterate = block_save_iterate,
1023 .save_live_complete_precopy = block_save_complete,
1024 .save_live_pending = block_save_pending,
1025 .load_state = block_load,
1026 .save_cleanup = block_migration_cleanup,
1027 .is_active = block_is_active,
1028 };
1029
blk_mig_init(void)1030 void blk_mig_init(void)
1031 {
1032 QSIMPLEQ_INIT(&block_mig_state.bmds_list);
1033 QSIMPLEQ_INIT(&block_mig_state.blk_list);
1034 qemu_mutex_init(&block_mig_state.lock);
1035
1036 register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
1037 &block_mig_state);
1038 }
1039