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 alias size ] \  flags & DEVICE_NAME
33  * [ n bytes: node alias     ] /
34  * [ 1 byte: bitmap alias size ] \  flags & BITMAP_NAME
35  * [ n bytes: bitmap alias     ] /
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 "block/dirty-bitmap.h"
65 #include "sysemu/block-backend.h"
66 #include "sysemu/runstate.h"
67 #include "qemu/main-loop.h"
68 #include "qemu/error-report.h"
69 #include "migration/misc.h"
70 #include "migration/migration.h"
71 #include "qemu-file.h"
72 #include "migration/vmstate.h"
73 #include "migration/register.h"
74 #include "qemu/hbitmap.h"
75 #include "qemu/cutils.h"
76 #include "qemu/id.h"
77 #include "qapi/error.h"
78 #include "qapi/qapi-commands-migration.h"
79 #include "qapi/qapi-visit-migration.h"
80 #include "qapi/clone-visitor.h"
81 #include "trace.h"
82 
83 #define CHUNK_SIZE     (1 << 10)
84 
85 /* Flags occupy one, two or four bytes (Big Endian). The size is determined as
86  * follows:
87  * in first (most significant) byte bit 8 is clear  -->  one byte
88  * in first byte bit 8 is set    -->  two or four bytes, depending on second
89  *                                    byte:
90  *    | in second byte bit 8 is clear  -->  two bytes
91  *    | in second byte bit 8 is set    -->  four bytes
92  */
93 #define DIRTY_BITMAP_MIG_FLAG_EOS           0x01
94 #define DIRTY_BITMAP_MIG_FLAG_ZEROES        0x02
95 #define DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME   0x04
96 #define DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME   0x08
97 #define DIRTY_BITMAP_MIG_FLAG_START         0x10
98 #define DIRTY_BITMAP_MIG_FLAG_COMPLETE      0x20
99 #define DIRTY_BITMAP_MIG_FLAG_BITS          0x40
100 
101 #define DIRTY_BITMAP_MIG_EXTRA_FLAGS        0x80
102 
103 #define DIRTY_BITMAP_MIG_START_FLAG_ENABLED          0x01
104 #define DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT       0x02
105 /* 0x04 was "AUTOLOAD" flags on older versions, now it is ignored */
106 #define DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK    0xf8
107 
108 /* State of one bitmap during save process */
109 typedef struct SaveBitmapState {
110     /* Written during setup phase. */
111     BlockDriverState *bs;
112     char *node_alias;
113     char *bitmap_alias;
114     BdrvDirtyBitmap *bitmap;
115     uint64_t total_sectors;
116     uint64_t sectors_per_chunk;
117     QSIMPLEQ_ENTRY(SaveBitmapState) entry;
118     uint8_t flags;
119 
120     /* For bulk phase. */
121     bool bulk_completed;
122     uint64_t cur_sector;
123 } SaveBitmapState;
124 
125 /* State of the dirty bitmap migration (DBM) during save process */
126 typedef struct DBMSaveState {
127     QSIMPLEQ_HEAD(, SaveBitmapState) dbms_list;
128 
129     bool bulk_completed;
130     bool no_bitmaps;
131 
132     /* for send_bitmap_bits() */
133     BlockDriverState *prev_bs;
134     BdrvDirtyBitmap *prev_bitmap;
135 } DBMSaveState;
136 
137 typedef struct LoadBitmapState {
138     BlockDriverState *bs;
139     BdrvDirtyBitmap *bitmap;
140     bool migrated;
141     bool enabled;
142 } LoadBitmapState;
143 
144 /* State of the dirty bitmap migration (DBM) during load process */
145 typedef struct DBMLoadState {
146     uint32_t flags;
147     char node_alias[256];
148     char bitmap_alias[256];
149     char bitmap_name[BDRV_BITMAP_MAX_NAME_SIZE + 1];
150     BlockDriverState *bs;
151     BdrvDirtyBitmap *bitmap;
152 
153     bool before_vm_start_handled; /* set in dirty_bitmap_mig_before_vm_start */
154     BitmapMigrationBitmapAlias *bmap_inner;
155 
156     /*
157      * cancelled
158      * Incoming migration is cancelled for some reason. That means that we
159      * still should read our chunks from migration stream, to not affect other
160      * migration objects (like RAM), but just ignore them and do not touch any
161      * bitmaps or nodes.
162      */
163     bool cancelled;
164 
165     GSList *bitmaps;
166     QemuMutex lock; /* protect bitmaps */
167 } DBMLoadState;
168 
169 typedef struct DBMState {
170     DBMSaveState save;
171     DBMLoadState load;
172 } DBMState;
173 
174 static DBMState dbm_state;
175 
176 /* For hash tables that map node/bitmap names to aliases */
177 typedef struct AliasMapInnerNode {
178     char *string;
179     GHashTable *subtree;
180 } AliasMapInnerNode;
181 
182 static void free_alias_map_inner_node(void *amin_ptr)
183 {
184     AliasMapInnerNode *amin = amin_ptr;
185 
186     g_free(amin->string);
187     g_hash_table_unref(amin->subtree);
188     g_free(amin);
189 }
190 
191 /**
192  * Construct an alias map based on the given QMP structure.
193  *
194  * (Note that we cannot store such maps in the MigrationParameters
195  * object, because that struct is defined by the QAPI schema, which
196  * makes it basically impossible to have dicts with arbitrary keys.
197  * Therefore, we instead have to construct these maps when migration
198  * starts.)
199  *
200  * @bbm is the block_bitmap_mapping from the migration parameters.
201  *
202  * If @name_to_alias is true, the returned hash table will map node
203  * and bitmap names to their respective aliases (for outgoing
204  * migration).
205  *
206  * If @name_to_alias is false, the returned hash table will map node
207  * and bitmap aliases to their respective names (for incoming
208  * migration).
209  *
210  * The hash table maps node names/aliases to AliasMapInnerNode
211  * objects, whose .string is the respective node alias/name, and whose
212  * .subtree table maps bitmap names/aliases to the respective bitmap
213  * alias/name.
214  */
215 static GHashTable *construct_alias_map(const BitmapMigrationNodeAliasList *bbm,
216                                        bool name_to_alias,
217                                        Error **errp)
218 {
219     GHashTable *alias_map;
220     size_t max_node_name_len = sizeof_field(BlockDriverState, node_name) - 1;
221 
222     alias_map = g_hash_table_new_full(g_str_hash, g_str_equal,
223                                       g_free, free_alias_map_inner_node);
224 
225     for (; bbm; bbm = bbm->next) {
226         const BitmapMigrationNodeAlias *bmna = bbm->value;
227         const BitmapMigrationBitmapAliasList *bmbal;
228         AliasMapInnerNode *amin;
229         GHashTable *bitmaps_map;
230         const char *node_map_from, *node_map_to;
231         GDestroyNotify gdn;
232 
233         if (!id_wellformed(bmna->alias)) {
234             error_setg(errp, "The node alias '%s' is not well-formed",
235                        bmna->alias);
236             goto fail;
237         }
238 
239         if (strlen(bmna->alias) > UINT8_MAX) {
240             error_setg(errp, "The node alias '%s' is longer than %u bytes",
241                        bmna->alias, UINT8_MAX);
242             goto fail;
243         }
244 
245         if (strlen(bmna->node_name) > max_node_name_len) {
246             error_setg(errp, "The node name '%s' is longer than %zu bytes",
247                        bmna->node_name, max_node_name_len);
248             goto fail;
249         }
250 
251         if (name_to_alias) {
252             if (g_hash_table_contains(alias_map, bmna->node_name)) {
253                 error_setg(errp, "The node name '%s' is mapped twice",
254                            bmna->node_name);
255                 goto fail;
256             }
257 
258             node_map_from = bmna->node_name;
259             node_map_to = bmna->alias;
260         } else {
261             if (g_hash_table_contains(alias_map, bmna->alias)) {
262                 error_setg(errp, "The node alias '%s' is used twice",
263                            bmna->alias);
264                 goto fail;
265             }
266 
267             node_map_from = bmna->alias;
268             node_map_to = bmna->node_name;
269         }
270 
271         gdn = (GDestroyNotify) qapi_free_BitmapMigrationBitmapAlias;
272         bitmaps_map = g_hash_table_new_full(g_str_hash, g_str_equal, g_free,
273                                             gdn);
274 
275         amin = g_new(AliasMapInnerNode, 1);
276         *amin = (AliasMapInnerNode){
277             .string = g_strdup(node_map_to),
278             .subtree = bitmaps_map,
279         };
280 
281         g_hash_table_insert(alias_map, g_strdup(node_map_from), amin);
282 
283         for (bmbal = bmna->bitmaps; bmbal; bmbal = bmbal->next) {
284             const BitmapMigrationBitmapAlias *bmba = bmbal->value;
285             const char *bmap_map_from;
286 
287             if (strlen(bmba->alias) > UINT8_MAX) {
288                 error_setg(errp,
289                            "The bitmap alias '%s' is longer than %u bytes",
290                            bmba->alias, UINT8_MAX);
291                 goto fail;
292             }
293 
294             if (strlen(bmba->name) > BDRV_BITMAP_MAX_NAME_SIZE) {
295                 error_setg(errp, "The bitmap name '%s' is longer than %d bytes",
296                            bmba->name, BDRV_BITMAP_MAX_NAME_SIZE);
297                 goto fail;
298             }
299 
300             if (name_to_alias) {
301                 bmap_map_from = bmba->name;
302 
303                 if (g_hash_table_contains(bitmaps_map, bmba->name)) {
304                     error_setg(errp, "The bitmap '%s'/'%s' is mapped twice",
305                                bmna->node_name, bmba->name);
306                     goto fail;
307                 }
308             } else {
309                 bmap_map_from = bmba->alias;
310 
311                 if (g_hash_table_contains(bitmaps_map, bmba->alias)) {
312                     error_setg(errp, "The bitmap alias '%s'/'%s' is used twice",
313                                bmna->alias, bmba->alias);
314                     goto fail;
315                 }
316             }
317 
318             g_hash_table_insert(bitmaps_map, g_strdup(bmap_map_from),
319                                 QAPI_CLONE(BitmapMigrationBitmapAlias, bmba));
320         }
321     }
322 
323     return alias_map;
324 
325 fail:
326     g_hash_table_destroy(alias_map);
327     return NULL;
328 }
329 
330 /**
331  * Run construct_alias_map() in both directions to check whether @bbm
332  * is valid.
333  * (This function is to be used by migration/migration.c to validate
334  * the user-specified block-bitmap-mapping migration parameter.)
335  *
336  * Returns true if and only if the mapping is valid.
337  */
338 bool check_dirty_bitmap_mig_alias_map(const BitmapMigrationNodeAliasList *bbm,
339                                       Error **errp)
340 {
341     GHashTable *alias_map;
342 
343     alias_map = construct_alias_map(bbm, true, errp);
344     if (!alias_map) {
345         return false;
346     }
347     g_hash_table_destroy(alias_map);
348 
349     alias_map = construct_alias_map(bbm, false, errp);
350     if (!alias_map) {
351         return false;
352     }
353     g_hash_table_destroy(alias_map);
354 
355     return true;
356 }
357 
358 static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
359 {
360     uint8_t flags = qemu_get_byte(f);
361     if (flags & DIRTY_BITMAP_MIG_EXTRA_FLAGS) {
362         flags = flags << 8 | qemu_get_byte(f);
363         if (flags & DIRTY_BITMAP_MIG_EXTRA_FLAGS) {
364             flags = flags << 16 | qemu_get_be16(f);
365         }
366     }
367 
368     return flags;
369 }
370 
371 static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
372 {
373     /* The code currently does not send flags as more than one byte */
374     assert(!(flags & (0xffffff00 | DIRTY_BITMAP_MIG_EXTRA_FLAGS)));
375 
376     qemu_put_byte(f, flags);
377 }
378 
379 static void send_bitmap_header(QEMUFile *f, DBMSaveState *s,
380                                SaveBitmapState *dbms, uint32_t additional_flags)
381 {
382     BlockDriverState *bs = dbms->bs;
383     BdrvDirtyBitmap *bitmap = dbms->bitmap;
384     uint32_t flags = additional_flags;
385     trace_send_bitmap_header_enter();
386 
387     if (bs != s->prev_bs) {
388         s->prev_bs = bs;
389         flags |= DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME;
390     }
391 
392     if (bitmap != s->prev_bitmap) {
393         s->prev_bitmap = bitmap;
394         flags |= DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME;
395     }
396 
397     qemu_put_bitmap_flags(f, flags);
398 
399     if (flags & DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME) {
400         qemu_put_counted_string(f, dbms->node_alias);
401     }
402 
403     if (flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
404         qemu_put_counted_string(f, dbms->bitmap_alias);
405     }
406 }
407 
408 static void send_bitmap_start(QEMUFile *f, DBMSaveState *s,
409                               SaveBitmapState *dbms)
410 {
411     send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_START);
412     qemu_put_be32(f, bdrv_dirty_bitmap_granularity(dbms->bitmap));
413     qemu_put_byte(f, dbms->flags);
414 }
415 
416 static void send_bitmap_complete(QEMUFile *f, DBMSaveState *s,
417                                  SaveBitmapState *dbms)
418 {
419     send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
420 }
421 
422 static void send_bitmap_bits(QEMUFile *f, DBMSaveState *s,
423                              SaveBitmapState *dbms,
424                              uint64_t start_sector, uint32_t nr_sectors)
425 {
426     /* align for buffer_is_zero() */
427     uint64_t align = 4 * sizeof(long);
428     uint64_t unaligned_size =
429         bdrv_dirty_bitmap_serialization_size(
430             dbms->bitmap, start_sector << BDRV_SECTOR_BITS,
431             (uint64_t)nr_sectors << BDRV_SECTOR_BITS);
432     uint64_t buf_size = QEMU_ALIGN_UP(unaligned_size, align);
433     uint8_t *buf = g_malloc0(buf_size);
434     uint32_t flags = DIRTY_BITMAP_MIG_FLAG_BITS;
435 
436     bdrv_dirty_bitmap_serialize_part(
437         dbms->bitmap, buf, start_sector << BDRV_SECTOR_BITS,
438         (uint64_t)nr_sectors << BDRV_SECTOR_BITS);
439 
440     if (buffer_is_zero(buf, buf_size)) {
441         g_free(buf);
442         buf = NULL;
443         flags |= DIRTY_BITMAP_MIG_FLAG_ZEROES;
444     }
445 
446     trace_send_bitmap_bits(flags, start_sector, nr_sectors, buf_size);
447 
448     send_bitmap_header(f, s, dbms, flags);
449 
450     qemu_put_be64(f, start_sector);
451     qemu_put_be32(f, nr_sectors);
452 
453     /* if a block is zero we need to flush here since the network
454      * bandwidth is now a lot higher than the storage device bandwidth.
455      * thus if we queue zero blocks we slow down the migration. */
456     if (flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
457         qemu_fflush(f);
458     } else {
459         qemu_put_be64(f, buf_size);
460         qemu_put_buffer(f, buf, buf_size);
461     }
462 
463     g_free(buf);
464 }
465 
466 /* Called with iothread lock taken.  */
467 static void dirty_bitmap_do_save_cleanup(DBMSaveState *s)
468 {
469     SaveBitmapState *dbms;
470 
471     while ((dbms = QSIMPLEQ_FIRST(&s->dbms_list)) != NULL) {
472         QSIMPLEQ_REMOVE_HEAD(&s->dbms_list, entry);
473         bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
474         bdrv_unref(dbms->bs);
475         g_free(dbms->node_alias);
476         g_free(dbms->bitmap_alias);
477         g_free(dbms);
478     }
479 }
480 
481 /* Called with iothread lock taken. */
482 static int add_bitmaps_to_list(DBMSaveState *s, BlockDriverState *bs,
483                                const char *bs_name, GHashTable *alias_map)
484 {
485     BdrvDirtyBitmap *bitmap;
486     SaveBitmapState *dbms;
487     GHashTable *bitmap_aliases;
488     const char *node_alias, *bitmap_name, *bitmap_alias;
489     Error *local_err = NULL;
490 
491     /* When an alias map is given, @bs_name must be @bs's node name */
492     assert(!alias_map || !strcmp(bs_name, bdrv_get_node_name(bs)));
493 
494     FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
495         if (bdrv_dirty_bitmap_name(bitmap)) {
496             break;
497         }
498     }
499     if (!bitmap) {
500         return 0;
501     }
502 
503     bitmap_name = bdrv_dirty_bitmap_name(bitmap);
504 
505     if (!bs_name || strcmp(bs_name, "") == 0) {
506         error_report("Bitmap '%s' in unnamed node can't be migrated",
507                      bitmap_name);
508         return -1;
509     }
510 
511     if (alias_map) {
512         const AliasMapInnerNode *amin = g_hash_table_lookup(alias_map, bs_name);
513 
514         if (!amin) {
515             /* Skip bitmaps on nodes with no alias */
516             return 0;
517         }
518 
519         node_alias = amin->string;
520         bitmap_aliases = amin->subtree;
521     } else {
522         node_alias = bs_name;
523         bitmap_aliases = NULL;
524     }
525 
526     if (node_alias[0] == '#') {
527         error_report("Bitmap '%s' in a node with auto-generated "
528                      "name '%s' can't be migrated",
529                      bitmap_name, node_alias);
530         return -1;
531     }
532 
533     FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
534         BitmapMigrationBitmapAliasTransform *bitmap_transform = NULL;
535         bitmap_name = bdrv_dirty_bitmap_name(bitmap);
536         if (!bitmap_name) {
537             continue;
538         }
539 
540         if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, &local_err)) {
541             error_report_err(local_err);
542             return -1;
543         }
544 
545         if (bitmap_aliases) {
546             BitmapMigrationBitmapAlias *bmap_inner;
547 
548             bmap_inner = g_hash_table_lookup(bitmap_aliases, bitmap_name);
549             if (!bmap_inner) {
550                 /* Skip bitmaps with no alias */
551                 continue;
552             }
553 
554             bitmap_alias = bmap_inner->alias;
555             if (bmap_inner->transform) {
556                 bitmap_transform = bmap_inner->transform;
557             }
558         } else {
559             if (strlen(bitmap_name) > UINT8_MAX) {
560                 error_report("Cannot migrate bitmap '%s' on node '%s': "
561                              "Name is longer than %u bytes",
562                              bitmap_name, bs_name, UINT8_MAX);
563                 return -1;
564             }
565             bitmap_alias = bitmap_name;
566         }
567 
568         bdrv_ref(bs);
569         bdrv_dirty_bitmap_set_busy(bitmap, true);
570 
571         dbms = g_new0(SaveBitmapState, 1);
572         dbms->bs = bs;
573         dbms->node_alias = g_strdup(node_alias);
574         dbms->bitmap_alias = g_strdup(bitmap_alias);
575         dbms->bitmap = bitmap;
576         dbms->total_sectors = bdrv_nb_sectors(bs);
577         dbms->sectors_per_chunk = CHUNK_SIZE * 8LLU *
578             (bdrv_dirty_bitmap_granularity(bitmap) >> BDRV_SECTOR_BITS);
579         assert(dbms->sectors_per_chunk != 0);
580         if (bdrv_dirty_bitmap_enabled(bitmap)) {
581             dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
582         }
583         if (bitmap_transform &&
584             bitmap_transform->has_persistent) {
585             if (bitmap_transform->persistent) {
586                 dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
587             }
588         } else {
589             if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
590                 dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
591             }
592         }
593 
594         QSIMPLEQ_INSERT_TAIL(&s->dbms_list, dbms, entry);
595     }
596 
597     return 0;
598 }
599 
600 /* Called with iothread lock taken. */
601 static int init_dirty_bitmap_migration(DBMSaveState *s)
602 {
603     BlockDriverState *bs;
604     SaveBitmapState *dbms;
605     GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL);
606     BlockBackend *blk;
607     const MigrationParameters *mig_params = &migrate_get_current()->parameters;
608     GHashTable *alias_map = NULL;
609 
610     if (mig_params->has_block_bitmap_mapping) {
611         alias_map = construct_alias_map(mig_params->block_bitmap_mapping, true,
612                                         &error_abort);
613     }
614 
615     s->bulk_completed = false;
616     s->prev_bs = NULL;
617     s->prev_bitmap = NULL;
618     s->no_bitmaps = false;
619 
620     if (!alias_map) {
621         /*
622          * Use blockdevice name for direct (or filtered) children of named block
623          * backends.
624          */
625         for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
626             const char *name = blk_name(blk);
627 
628             if (!name || strcmp(name, "") == 0) {
629                 continue;
630             }
631 
632             bs = blk_bs(blk);
633 
634             /* Skip filters without bitmaps */
635             while (bs && bs->drv && bs->drv->is_filter &&
636                    !bdrv_has_named_bitmaps(bs))
637             {
638                 bs = bdrv_filter_bs(bs);
639             }
640 
641             if (bs && bs->drv && !bs->drv->is_filter) {
642                 if (add_bitmaps_to_list(s, bs, name, NULL)) {
643                     goto fail;
644                 }
645                 g_hash_table_add(handled_by_blk, bs);
646             }
647         }
648     }
649 
650     for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
651         if (g_hash_table_contains(handled_by_blk, bs)) {
652             continue;
653         }
654 
655         if (add_bitmaps_to_list(s, bs, bdrv_get_node_name(bs), alias_map)) {
656             goto fail;
657         }
658     }
659 
660     /* unset migration flags here, to not roll back it */
661     QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
662         bdrv_dirty_bitmap_skip_store(dbms->bitmap, true);
663     }
664 
665     if (QSIMPLEQ_EMPTY(&s->dbms_list)) {
666         s->no_bitmaps = true;
667     }
668 
669     g_hash_table_destroy(handled_by_blk);
670     if (alias_map) {
671         g_hash_table_destroy(alias_map);
672     }
673 
674     return 0;
675 
676 fail:
677     g_hash_table_destroy(handled_by_blk);
678     if (alias_map) {
679         g_hash_table_destroy(alias_map);
680     }
681     dirty_bitmap_do_save_cleanup(s);
682 
683     return -1;
684 }
685 
686 /* Called with no lock taken.  */
687 static void bulk_phase_send_chunk(QEMUFile *f, DBMSaveState *s,
688                                   SaveBitmapState *dbms)
689 {
690     uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
691                              dbms->sectors_per_chunk);
692 
693     send_bitmap_bits(f, s, dbms, dbms->cur_sector, nr_sectors);
694 
695     dbms->cur_sector += nr_sectors;
696     if (dbms->cur_sector >= dbms->total_sectors) {
697         dbms->bulk_completed = true;
698     }
699 }
700 
701 /* Called with no lock taken.  */
702 static void bulk_phase(QEMUFile *f, DBMSaveState *s, bool limit)
703 {
704     SaveBitmapState *dbms;
705 
706     QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
707         while (!dbms->bulk_completed) {
708             bulk_phase_send_chunk(f, s, dbms);
709             if (limit && qemu_file_rate_limit(f)) {
710                 return;
711             }
712         }
713     }
714 
715     s->bulk_completed = true;
716 }
717 
718 /* for SaveVMHandlers */
719 static void dirty_bitmap_save_cleanup(void *opaque)
720 {
721     DBMSaveState *s = &((DBMState *)opaque)->save;
722 
723     dirty_bitmap_do_save_cleanup(s);
724 }
725 
726 static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
727 {
728     DBMSaveState *s = &((DBMState *)opaque)->save;
729 
730     trace_dirty_bitmap_save_iterate(migration_in_postcopy());
731 
732     if (migration_in_postcopy() && !s->bulk_completed) {
733         bulk_phase(f, s, true);
734     }
735 
736     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
737 
738     return s->bulk_completed;
739 }
740 
741 /* Called with iothread lock taken.  */
742 
743 static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
744 {
745     DBMSaveState *s = &((DBMState *)opaque)->save;
746     SaveBitmapState *dbms;
747     trace_dirty_bitmap_save_complete_enter();
748 
749     if (!s->bulk_completed) {
750         bulk_phase(f, s, false);
751     }
752 
753     QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
754         send_bitmap_complete(f, s, dbms);
755     }
756 
757     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
758 
759     trace_dirty_bitmap_save_complete_finish();
760 
761     dirty_bitmap_save_cleanup(opaque);
762     return 0;
763 }
764 
765 static void dirty_bitmap_state_pending(void *opaque,
766                                        uint64_t *res_precopy_only,
767                                        uint64_t *res_compatible,
768                                        uint64_t *res_postcopy_only)
769 {
770     DBMSaveState *s = &((DBMState *)opaque)->save;
771     SaveBitmapState *dbms;
772     uint64_t pending = 0;
773 
774     qemu_mutex_lock_iothread();
775 
776     QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
777         uint64_t gran = bdrv_dirty_bitmap_granularity(dbms->bitmap);
778         uint64_t sectors = dbms->bulk_completed ? 0 :
779                            dbms->total_sectors - dbms->cur_sector;
780 
781         pending += DIV_ROUND_UP(sectors * BDRV_SECTOR_SIZE, gran);
782     }
783 
784     qemu_mutex_unlock_iothread();
785 
786     trace_dirty_bitmap_state_pending(pending);
787 
788     *res_postcopy_only += pending;
789 }
790 
791 /* First occurrence of this bitmap. It should be created if doesn't exist */
792 static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
793 {
794     Error *local_err = NULL;
795     uint32_t granularity = qemu_get_be32(f);
796     uint8_t flags = qemu_get_byte(f);
797     LoadBitmapState *b;
798     bool persistent;
799 
800     if (s->cancelled) {
801         return 0;
802     }
803 
804     if (s->bitmap) {
805         error_report("Bitmap with the same name ('%s') already exists on "
806                      "destination", bdrv_dirty_bitmap_name(s->bitmap));
807         return -EINVAL;
808     } else {
809         s->bitmap = bdrv_create_dirty_bitmap(s->bs, granularity,
810                                              s->bitmap_name, &local_err);
811         if (!s->bitmap) {
812             error_report_err(local_err);
813             return -EINVAL;
814         }
815     }
816 
817     if (flags & DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK) {
818         error_report("Unknown flags in migrated dirty bitmap header: %x",
819                      flags);
820         return -EINVAL;
821     }
822 
823     if (s->bmap_inner &&
824         s->bmap_inner->transform &&
825         s->bmap_inner->transform->has_persistent) {
826         persistent = s->bmap_inner->transform->persistent;
827     } else {
828         persistent = flags & DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
829     }
830 
831     if (persistent) {
832         bdrv_dirty_bitmap_set_persistence(s->bitmap, true);
833     }
834 
835     bdrv_disable_dirty_bitmap(s->bitmap);
836     if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
837         bdrv_dirty_bitmap_create_successor(s->bitmap, &local_err);
838         if (local_err) {
839             error_report_err(local_err);
840             return -EINVAL;
841         }
842     } else {
843         bdrv_dirty_bitmap_set_busy(s->bitmap, true);
844     }
845 
846     b = g_new(LoadBitmapState, 1);
847     b->bs = s->bs;
848     b->bitmap = s->bitmap;
849     b->migrated = false;
850     b->enabled = flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
851 
852     s->bitmaps = g_slist_prepend(s->bitmaps, b);
853 
854     return 0;
855 }
856 
857 /*
858  * before_vm_start_handle_item
859  *
860  * g_slist_foreach helper
861  *
862  * item is LoadBitmapState*
863  * opaque is DBMLoadState*
864  */
865 static void before_vm_start_handle_item(void *item, void *opaque)
866 {
867     DBMLoadState *s = opaque;
868     LoadBitmapState *b = item;
869 
870     if (b->enabled) {
871         if (b->migrated) {
872             bdrv_enable_dirty_bitmap(b->bitmap);
873         } else {
874             bdrv_dirty_bitmap_enable_successor(b->bitmap);
875         }
876     }
877 
878     if (b->migrated) {
879         s->bitmaps = g_slist_remove(s->bitmaps, b);
880         g_free(b);
881     }
882 }
883 
884 void dirty_bitmap_mig_before_vm_start(void)
885 {
886     DBMLoadState *s = &dbm_state.load;
887     qemu_mutex_lock(&s->lock);
888 
889     assert(!s->before_vm_start_handled);
890     g_slist_foreach(s->bitmaps, before_vm_start_handle_item, s);
891     s->before_vm_start_handled = true;
892 
893     qemu_mutex_unlock(&s->lock);
894 }
895 
896 static void cancel_incoming_locked(DBMLoadState *s)
897 {
898     GSList *item;
899 
900     if (s->cancelled) {
901         return;
902     }
903 
904     s->cancelled = true;
905     s->bs = NULL;
906     s->bitmap = NULL;
907 
908     /* Drop all unfinished bitmaps */
909     for (item = s->bitmaps; item; item = g_slist_next(item)) {
910         LoadBitmapState *b = item->data;
911 
912         /*
913          * Bitmap must be unfinished, as finished bitmaps should already be
914          * removed from the list.
915          */
916         assert(!s->before_vm_start_handled || !b->migrated);
917         if (bdrv_dirty_bitmap_has_successor(b->bitmap)) {
918             bdrv_reclaim_dirty_bitmap(b->bitmap, &error_abort);
919         } else {
920             bdrv_dirty_bitmap_set_busy(b->bitmap, false);
921         }
922         bdrv_release_dirty_bitmap(b->bitmap);
923     }
924 
925     g_slist_free_full(s->bitmaps, g_free);
926     s->bitmaps = NULL;
927 }
928 
929 void dirty_bitmap_mig_cancel_outgoing(void)
930 {
931     dirty_bitmap_do_save_cleanup(&dbm_state.save);
932 }
933 
934 void dirty_bitmap_mig_cancel_incoming(void)
935 {
936     DBMLoadState *s = &dbm_state.load;
937 
938     qemu_mutex_lock(&s->lock);
939 
940     cancel_incoming_locked(s);
941 
942     qemu_mutex_unlock(&s->lock);
943 }
944 
945 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
946 {
947     GSList *item;
948     trace_dirty_bitmap_load_complete();
949 
950     if (s->cancelled) {
951         return;
952     }
953 
954     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);
955 
956     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
957         bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
958     } else {
959         bdrv_dirty_bitmap_set_busy(s->bitmap, false);
960     }
961 
962     for (item = s->bitmaps; item; item = g_slist_next(item)) {
963         LoadBitmapState *b = item->data;
964 
965         if (b->bitmap == s->bitmap) {
966             b->migrated = true;
967             if (s->before_vm_start_handled) {
968                 s->bitmaps = g_slist_remove(s->bitmaps, b);
969                 g_free(b);
970             }
971             break;
972         }
973     }
974 }
975 
976 static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
977 {
978     uint64_t first_byte = qemu_get_be64(f) << BDRV_SECTOR_BITS;
979     uint64_t nr_bytes = (uint64_t)qemu_get_be32(f) << BDRV_SECTOR_BITS;
980     trace_dirty_bitmap_load_bits_enter(first_byte >> BDRV_SECTOR_BITS,
981                                        nr_bytes >> BDRV_SECTOR_BITS);
982 
983     if (s->flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
984         trace_dirty_bitmap_load_bits_zeroes();
985         if (!s->cancelled) {
986             bdrv_dirty_bitmap_deserialize_zeroes(s->bitmap, first_byte,
987                                                  nr_bytes, false);
988         }
989     } else {
990         size_t ret;
991         g_autofree uint8_t *buf = NULL;
992         uint64_t buf_size = qemu_get_be64(f);
993         uint64_t needed_size;
994 
995         /*
996          * The actual check for buf_size is done a bit later. We can't do it in
997          * cancelled mode as we don't have the bitmap to check the constraints
998          * (so, we allocate a buffer and read prior to the check). On the other
999          * hand, we shouldn't blindly g_malloc the number from the stream.
1000          * Actually one chunk should not be larger than CHUNK_SIZE. Let's allow
1001          * a bit larger (which means that bitmap migration will fail anyway and
1002          * the whole migration will most probably fail soon due to broken
1003          * stream).
1004          */
1005         if (buf_size > 10 * CHUNK_SIZE) {
1006             error_report("Bitmap migration stream buffer allocation request "
1007                          "is too large");
1008             return -EIO;
1009         }
1010 
1011         buf = g_malloc(buf_size);
1012         ret = qemu_get_buffer(f, buf, buf_size);
1013         if (ret != buf_size) {
1014             error_report("Failed to read bitmap bits");
1015             return -EIO;
1016         }
1017 
1018         if (s->cancelled) {
1019             return 0;
1020         }
1021 
1022         needed_size = bdrv_dirty_bitmap_serialization_size(s->bitmap,
1023                                                            first_byte,
1024                                                            nr_bytes);
1025 
1026         if (needed_size > buf_size ||
1027             buf_size > QEMU_ALIGN_UP(needed_size, 4 * sizeof(long))
1028              /* Here used same alignment as in send_bitmap_bits */
1029         ) {
1030             error_report("Migrated bitmap granularity doesn't "
1031                          "match the destination bitmap '%s' granularity",
1032                          bdrv_dirty_bitmap_name(s->bitmap));
1033             cancel_incoming_locked(s);
1034             return 0;
1035         }
1036 
1037         bdrv_dirty_bitmap_deserialize_part(s->bitmap, buf, first_byte, nr_bytes,
1038                                            false);
1039     }
1040 
1041     return 0;
1042 }
1043 
1044 static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
1045                                     GHashTable *alias_map)
1046 {
1047     GHashTable *bitmap_alias_map = NULL;
1048     Error *local_err = NULL;
1049     bool nothing;
1050     s->flags = qemu_get_bitmap_flags(f);
1051     trace_dirty_bitmap_load_header(s->flags);
1052 
1053     nothing = s->flags == (s->flags & DIRTY_BITMAP_MIG_FLAG_EOS);
1054 
1055     if (s->flags & DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME) {
1056         if (!qemu_get_counted_string(f, s->node_alias)) {
1057             error_report("Unable to read node alias string");
1058             return -EINVAL;
1059         }
1060 
1061         if (!s->cancelled) {
1062             if (alias_map) {
1063                 const AliasMapInnerNode *amin;
1064 
1065                 amin = g_hash_table_lookup(alias_map, s->node_alias);
1066                 if (!amin) {
1067                     error_setg(&local_err, "Error: Unknown node alias '%s'",
1068                                s->node_alias);
1069                     s->bs = NULL;
1070                 } else {
1071                     bitmap_alias_map = amin->subtree;
1072                     s->bs = bdrv_lookup_bs(NULL, amin->string, &local_err);
1073                 }
1074             } else {
1075                 s->bs = bdrv_lookup_bs(s->node_alias, s->node_alias,
1076                                        &local_err);
1077             }
1078             if (!s->bs) {
1079                 error_report_err(local_err);
1080                 cancel_incoming_locked(s);
1081             }
1082         }
1083     } else if (s->bs) {
1084         if (alias_map) {
1085             const AliasMapInnerNode *amin;
1086 
1087             /* Must be present in the map, or s->bs would not be set */
1088             amin = g_hash_table_lookup(alias_map, s->node_alias);
1089             assert(amin != NULL);
1090 
1091             bitmap_alias_map = amin->subtree;
1092         }
1093     } else if (!nothing && !s->cancelled) {
1094         error_report("Error: block device name is not set");
1095         cancel_incoming_locked(s);
1096     }
1097 
1098     assert(nothing || s->cancelled || !!alias_map == !!bitmap_alias_map);
1099 
1100     if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
1101         const char *bitmap_name;
1102 
1103         if (!qemu_get_counted_string(f, s->bitmap_alias)) {
1104             error_report("Unable to read bitmap alias string");
1105             return -EINVAL;
1106         }
1107 
1108         bitmap_name = s->bitmap_alias;
1109         if (!s->cancelled && bitmap_alias_map) {
1110             BitmapMigrationBitmapAlias *bmap_inner;
1111 
1112             bmap_inner = g_hash_table_lookup(bitmap_alias_map, s->bitmap_alias);
1113             if (!bmap_inner) {
1114                 error_report("Error: Unknown bitmap alias '%s' on node "
1115                              "'%s' (alias '%s')", s->bitmap_alias,
1116                              s->bs->node_name, s->node_alias);
1117                 cancel_incoming_locked(s);
1118             } else {
1119                 bitmap_name = bmap_inner->name;
1120             }
1121 
1122             s->bmap_inner = bmap_inner;
1123         }
1124 
1125         if (!s->cancelled) {
1126             g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
1127             s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
1128 
1129             /*
1130              * bitmap may be NULL here, it wouldn't be an error if it is the
1131              * first occurrence of the bitmap
1132              */
1133             if (!s->bitmap && !(s->flags & DIRTY_BITMAP_MIG_FLAG_START)) {
1134                 error_report("Error: unknown dirty bitmap "
1135                              "'%s' for block device '%s'",
1136                              s->bitmap_name, s->bs->node_name);
1137                 cancel_incoming_locked(s);
1138             }
1139         }
1140     } else if (!s->bitmap && !nothing && !s->cancelled) {
1141         error_report("Error: block device name is not set");
1142         cancel_incoming_locked(s);
1143     }
1144 
1145     return 0;
1146 }
1147 
1148 /*
1149  * dirty_bitmap_load
1150  *
1151  * Load sequence of dirty bitmap chunks. Return error only on fatal io stream
1152  * violations. On other errors just cancel bitmaps incoming migration and return
1153  * 0.
1154  *
1155  * Note, than when incoming bitmap migration is canceled, we still must read all
1156  * our chunks (and just ignore them), to not affect other migration objects.
1157  */
1158 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
1159 {
1160     GHashTable *alias_map = NULL;
1161     const MigrationParameters *mig_params = &migrate_get_current()->parameters;
1162     DBMLoadState *s = &((DBMState *)opaque)->load;
1163     int ret = 0;
1164 
1165     trace_dirty_bitmap_load_enter();
1166 
1167     if (version_id != 1) {
1168         QEMU_LOCK_GUARD(&s->lock);
1169         cancel_incoming_locked(s);
1170         return -EINVAL;
1171     }
1172 
1173     if (mig_params->has_block_bitmap_mapping) {
1174         alias_map = construct_alias_map(mig_params->block_bitmap_mapping,
1175                                         false, &error_abort);
1176     }
1177 
1178     do {
1179         QEMU_LOCK_GUARD(&s->lock);
1180 
1181         ret = dirty_bitmap_load_header(f, s, alias_map);
1182         if (ret < 0) {
1183             cancel_incoming_locked(s);
1184             goto fail;
1185         }
1186 
1187         if (s->flags & DIRTY_BITMAP_MIG_FLAG_START) {
1188             ret = dirty_bitmap_load_start(f, s);
1189         } else if (s->flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
1190             dirty_bitmap_load_complete(f, s);
1191         } else if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
1192             ret = dirty_bitmap_load_bits(f, s);
1193         }
1194 
1195         if (!ret) {
1196             ret = qemu_file_get_error(f);
1197         }
1198 
1199         if (ret) {
1200             cancel_incoming_locked(s);
1201             goto fail;
1202         }
1203     } while (!(s->flags & DIRTY_BITMAP_MIG_FLAG_EOS));
1204 
1205     trace_dirty_bitmap_load_success();
1206     ret = 0;
1207 fail:
1208     if (alias_map) {
1209         g_hash_table_destroy(alias_map);
1210     }
1211     return ret;
1212 }
1213 
1214 static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
1215 {
1216     DBMSaveState *s = &((DBMState *)opaque)->save;
1217     SaveBitmapState *dbms = NULL;
1218 
1219     qemu_mutex_lock_iothread();
1220     if (init_dirty_bitmap_migration(s) < 0) {
1221         qemu_mutex_unlock_iothread();
1222         return -1;
1223     }
1224 
1225     QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
1226         send_bitmap_start(f, s, dbms);
1227     }
1228     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
1229     qemu_mutex_unlock_iothread();
1230     return 0;
1231 }
1232 
1233 static bool dirty_bitmap_is_active(void *opaque)
1234 {
1235     DBMSaveState *s = &((DBMState *)opaque)->save;
1236 
1237     return migrate_dirty_bitmaps() && !s->no_bitmaps;
1238 }
1239 
1240 static bool dirty_bitmap_is_active_iterate(void *opaque)
1241 {
1242     return dirty_bitmap_is_active(opaque) && !runstate_is_running();
1243 }
1244 
1245 static bool dirty_bitmap_has_postcopy(void *opaque)
1246 {
1247     return true;
1248 }
1249 
1250 static SaveVMHandlers savevm_dirty_bitmap_handlers = {
1251     .save_setup = dirty_bitmap_save_setup,
1252     .save_live_complete_postcopy = dirty_bitmap_save_complete,
1253     .save_live_complete_precopy = dirty_bitmap_save_complete,
1254     .has_postcopy = dirty_bitmap_has_postcopy,
1255     .state_pending_exact = dirty_bitmap_state_pending,
1256     .state_pending_estimate = dirty_bitmap_state_pending,
1257     .save_live_iterate = dirty_bitmap_save_iterate,
1258     .is_active_iterate = dirty_bitmap_is_active_iterate,
1259     .load_state = dirty_bitmap_load,
1260     .save_cleanup = dirty_bitmap_save_cleanup,
1261     .is_active = dirty_bitmap_is_active,
1262 };
1263 
1264 void dirty_bitmap_mig_init(void)
1265 {
1266     QSIMPLEQ_INIT(&dbm_state.save.dbms_list);
1267     qemu_mutex_init(&dbm_state.load.lock);
1268 
1269     register_savevm_live("dirty-bitmap", 0, 1,
1270                          &savevm_dirty_bitmap_handlers,
1271                          &dbm_state);
1272 }
1273