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xemu/migration/block-dirty-bitmap.c
Vladimir Sementsov-Ogievskiy 4290b4834c migration/block-dirty-bitmap: make incoming disabled bitmaps busy 
Incoming enabled bitmaps are busy, because we do
bdrv_dirty_bitmap_create_successor() for them. But disabled bitmaps
being migrated are not marked busy, and user can remove them during the
incoming migration. Then we may crash in cancel_incoming_locked() when
try to remove the bitmap that was already removed by user, like this:

 #0  qemu_mutex_lock_impl (mutex=0x5593d88c50d1, file=0x559680554b20
   "../block/dirty-bitmap.c", line=64) at ../util/qemu-thread-posix.c:77
 #1  bdrv_dirty_bitmaps_lock (bs=0x5593d88c0ee9)
   at ../block/dirty-bitmap.c:64
 #2  bdrv_release_dirty_bitmap (bitmap=0x5596810e9570)
   at ../block/dirty-bitmap.c:362
 #3  cancel_incoming_locked (s=0x559680be8208 <dbm_state+40>)
   at ../migration/block-dirty-bitmap.c:918
 #4  dirty_bitmap_load (f=0x559681d02b10, opaque=0x559680be81e0
   <dbm_state>, version_id=1) at ../migration/block-dirty-bitmap.c:1194
 #5  vmstate_load (f=0x559681d02b10, se=0x559680fb5810)
   at ../migration/savevm.c:908
 #6  qemu_loadvm_section_part_end (f=0x559681d02b10,
   mis=0x559680fb4a30) at ../migration/savevm.c:2473
 #7  qemu_loadvm_state_main (f=0x559681d02b10, mis=0x559680fb4a30)
   at ../migration/savevm.c:2626
 #8  postcopy_ram_listen_thread (opaque=0x0)
   at ../migration/savevm.c:1871
 #9  qemu_thread_start (args=0x5596817ccd10)
   at ../util/qemu-thread-posix.c:521
 #10 start_thread () at /lib64/libpthread.so.0
 #11 clone () at /lib64/libc.so.6

Note bs pointer taken from bitmap: it's definitely bad aligned. That's
because we are in use after free, bitmap is already freed.

So, let's make disabled bitmaps (being migrated) busy during incoming
migration.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210322094906.5079-2-vsementsov@virtuozzo.com>
2021-03-24 13:41:19 +00:00

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/*
* Block dirty bitmap postcopy migration
*
* Copyright IBM, Corp. 2009
* Copyright (c) 2016-2017 Virtuozzo International GmbH. All rights reserved.
*
* Authors:
* Liran Schour <lirans@il.ibm.com>
* Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
* This file is derived from migration/block.c, so it's author and IBM copyright
* are here, although content is quite different.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*
* ***
*
* Here postcopy migration of dirty bitmaps is realized. Only QMP-addressable
* bitmaps are migrated.
*
* Bitmap migration implies creating bitmap with the same name and granularity
* in destination QEMU. If the bitmap with the same name (for the same node)
* already exists on destination an error will be generated.
*
* format of migration:
*
* # Header (shared for different chunk types)
* 1, 2 or 4 bytes: flags (see qemu_{put,put}_flags)
* [ 1 byte: node alias size ] \ flags & DEVICE_NAME
* [ n bytes: node alias ] /
* [ 1 byte: bitmap alias size ] \ flags & BITMAP_NAME
* [ n bytes: bitmap alias ] /
*
* # Start of bitmap migration (flags & START)
* header
* be64: granularity
* 1 byte: bitmap flags (corresponds to BdrvDirtyBitmap)
* bit 0 - bitmap is enabled
* bit 1 - bitmap is persistent
* bit 2 - bitmap is autoloading
* bits 3-7 - reserved, must be zero
*
* # Complete of bitmap migration (flags & COMPLETE)
* header
*
* # Data chunk of bitmap migration
* header
* be64: start sector
* be32: number of sectors
* [ be64: buffer size ] \ ! (flags & ZEROES)
* [ n bytes: buffer ] /
*
* The last chunk in stream should contain flags & EOS. The chunk may skip
* device and/or bitmap names, assuming them to be the same with the previous
* chunk.
*/
#include "qemu/osdep.h"
#include "block/block.h"
#include "block/block_int.h"
#include "sysemu/block-backend.h"
#include "sysemu/runstate.h"
#include "qemu/main-loop.h"
#include "qemu/error-report.h"
#include "migration/misc.h"
#include "migration/migration.h"
#include "qemu-file.h"
#include "migration/vmstate.h"
#include "migration/register.h"
#include "qemu/hbitmap.h"
#include "qemu/cutils.h"
#include "qemu/id.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-migration.h"
#include "qapi/qapi-visit-migration.h"
#include "qapi/clone-visitor.h"
#include "trace.h"
#define CHUNK_SIZE (1 << 10)
/* Flags occupy one, two or four bytes (Big Endian). The size is determined as
* follows:
* in first (most significant) byte bit 8 is clear --> one byte
* in first byte bit 8 is set --> two or four bytes, depending on second
* byte:
* | in second byte bit 8 is clear --> two bytes
* | in second byte bit 8 is set --> four bytes
*/
#define DIRTY_BITMAP_MIG_FLAG_EOS 0x01
#define DIRTY_BITMAP_MIG_FLAG_ZEROES 0x02
#define DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME 0x04
#define DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME 0x08
#define DIRTY_BITMAP_MIG_FLAG_START 0x10
#define DIRTY_BITMAP_MIG_FLAG_COMPLETE 0x20
#define DIRTY_BITMAP_MIG_FLAG_BITS 0x40
#define DIRTY_BITMAP_MIG_EXTRA_FLAGS 0x80
#define DIRTY_BITMAP_MIG_START_FLAG_ENABLED 0x01
#define DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT 0x02
/* 0x04 was "AUTOLOAD" flags on older versions, now it is ignored */
#define DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK 0xf8
/* State of one bitmap during save process */
typedef struct SaveBitmapState {
/* Written during setup phase. */
BlockDriverState *bs;
char *node_alias;
char *bitmap_alias;
BdrvDirtyBitmap *bitmap;
uint64_t total_sectors;
uint64_t sectors_per_chunk;
QSIMPLEQ_ENTRY(SaveBitmapState) entry;
uint8_t flags;
/* For bulk phase. */
bool bulk_completed;
uint64_t cur_sector;
} SaveBitmapState;
/* State of the dirty bitmap migration (DBM) during save process */
typedef struct DBMSaveState {
QSIMPLEQ_HEAD(, SaveBitmapState) dbms_list;
bool bulk_completed;
bool no_bitmaps;
/* for send_bitmap_bits() */
BlockDriverState *prev_bs;
BdrvDirtyBitmap *prev_bitmap;
} DBMSaveState;
typedef struct LoadBitmapState {
BlockDriverState *bs;
BdrvDirtyBitmap *bitmap;
bool migrated;
bool enabled;
} LoadBitmapState;
/* State of the dirty bitmap migration (DBM) during load process */
typedef struct DBMLoadState {
uint32_t flags;
char node_alias[256];
char bitmap_alias[256];
char bitmap_name[BDRV_BITMAP_MAX_NAME_SIZE + 1];
BlockDriverState *bs;
BdrvDirtyBitmap *bitmap;
bool before_vm_start_handled; /* set in dirty_bitmap_mig_before_vm_start */
BitmapMigrationBitmapAlias *bmap_inner;
/*
* cancelled
* Incoming migration is cancelled for some reason. That means that we
* still should read our chunks from migration stream, to not affect other
* migration objects (like RAM), but just ignore them and do not touch any
* bitmaps or nodes.
*/
bool cancelled;
GSList *bitmaps;
QemuMutex lock; /* protect bitmaps */
} DBMLoadState;
typedef struct DBMState {
DBMSaveState save;
DBMLoadState load;
} DBMState;
static DBMState dbm_state;
/* For hash tables that map node/bitmap names to aliases */
typedef struct AliasMapInnerNode {
char *string;
GHashTable *subtree;
} AliasMapInnerNode;
static void free_alias_map_inner_node(void *amin_ptr)
{
AliasMapInnerNode *amin = amin_ptr;
g_free(amin->string);
g_hash_table_unref(amin->subtree);
g_free(amin);
}
/**
* Construct an alias map based on the given QMP structure.
*
* (Note that we cannot store such maps in the MigrationParameters
* object, because that struct is defined by the QAPI schema, which
* makes it basically impossible to have dicts with arbitrary keys.
* Therefore, we instead have to construct these maps when migration
* starts.)
*
* @bbm is the block_bitmap_mapping from the migration parameters.
*
* If @name_to_alias is true, the returned hash table will map node
* and bitmap names to their respective aliases (for outgoing
* migration).
*
* If @name_to_alias is false, the returned hash table will map node
* and bitmap aliases to their respective names (for incoming
* migration).
*
* The hash table maps node names/aliases to AliasMapInnerNode
* objects, whose .string is the respective node alias/name, and whose
* .subtree table maps bitmap names/aliases to the respective bitmap
* alias/name.
*/
static GHashTable *construct_alias_map(const BitmapMigrationNodeAliasList *bbm,
bool name_to_alias,
Error **errp)
{
GHashTable *alias_map;
size_t max_node_name_len = sizeof_field(BlockDriverState, node_name) - 1;
alias_map = g_hash_table_new_full(g_str_hash, g_str_equal,
g_free, free_alias_map_inner_node);
for (; bbm; bbm = bbm->next) {
const BitmapMigrationNodeAlias *bmna = bbm->value;
const BitmapMigrationBitmapAliasList *bmbal;
AliasMapInnerNode *amin;
GHashTable *bitmaps_map;
const char *node_map_from, *node_map_to;
GDestroyNotify gdn;
if (!id_wellformed(bmna->alias)) {
error_setg(errp, "The node alias '%s' is not well-formed",
bmna->alias);
goto fail;
}
if (strlen(bmna->alias) > UINT8_MAX) {
error_setg(errp, "The node alias '%s' is longer than %u bytes",
bmna->alias, UINT8_MAX);
goto fail;
}
if (strlen(bmna->node_name) > max_node_name_len) {
error_setg(errp, "The node name '%s' is longer than %zu bytes",
bmna->node_name, max_node_name_len);
goto fail;
}
if (name_to_alias) {
if (g_hash_table_contains(alias_map, bmna->node_name)) {
error_setg(errp, "The node name '%s' is mapped twice",
bmna->node_name);
goto fail;
}
node_map_from = bmna->node_name;
node_map_to = bmna->alias;
} else {
if (g_hash_table_contains(alias_map, bmna->alias)) {
error_setg(errp, "The node alias '%s' is used twice",
bmna->alias);
goto fail;
}
node_map_from = bmna->alias;
node_map_to = bmna->node_name;
}
gdn = (GDestroyNotify) qapi_free_BitmapMigrationBitmapAlias;
bitmaps_map = g_hash_table_new_full(g_str_hash, g_str_equal, g_free,
gdn);
amin = g_new(AliasMapInnerNode, 1);
*amin = (AliasMapInnerNode){
.string = g_strdup(node_map_to),
.subtree = bitmaps_map,
};
g_hash_table_insert(alias_map, g_strdup(node_map_from), amin);
for (bmbal = bmna->bitmaps; bmbal; bmbal = bmbal->next) {
const BitmapMigrationBitmapAlias *bmba = bmbal->value;
const char *bmap_map_from;
if (strlen(bmba->alias) > UINT8_MAX) {
error_setg(errp,
"The bitmap alias '%s' is longer than %u bytes",
bmba->alias, UINT8_MAX);
goto fail;
}
if (strlen(bmba->name) > BDRV_BITMAP_MAX_NAME_SIZE) {
error_setg(errp, "The bitmap name '%s' is longer than %d bytes",
bmba->name, BDRV_BITMAP_MAX_NAME_SIZE);
goto fail;
}
if (name_to_alias) {
bmap_map_from = bmba->name;
if (g_hash_table_contains(bitmaps_map, bmba->name)) {
error_setg(errp, "The bitmap '%s'/'%s' is mapped twice",
bmna->node_name, bmba->name);
goto fail;
}
} else {
bmap_map_from = bmba->alias;
if (g_hash_table_contains(bitmaps_map, bmba->alias)) {
error_setg(errp, "The bitmap alias '%s'/'%s' is used twice",
bmna->alias, bmba->alias);
goto fail;
}
}
g_hash_table_insert(bitmaps_map, g_strdup(bmap_map_from),
QAPI_CLONE(BitmapMigrationBitmapAlias, bmba));
}
}
return alias_map;
fail:
g_hash_table_destroy(alias_map);
return NULL;
}
/**
* Run construct_alias_map() in both directions to check whether @bbm
* is valid.
* (This function is to be used by migration/migration.c to validate
* the user-specified block-bitmap-mapping migration parameter.)
*
* Returns true if and only if the mapping is valid.
*/
bool check_dirty_bitmap_mig_alias_map(const BitmapMigrationNodeAliasList *bbm,
Error **errp)
{
GHashTable *alias_map;
alias_map = construct_alias_map(bbm, true, errp);
if (!alias_map) {
return false;
}
g_hash_table_destroy(alias_map);
alias_map = construct_alias_map(bbm, false, errp);
if (!alias_map) {
return false;
}
g_hash_table_destroy(alias_map);
return true;
}
static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
{
uint8_t flags = qemu_get_byte(f);
if (flags & DIRTY_BITMAP_MIG_EXTRA_FLAGS) {
flags = flags << 8 | qemu_get_byte(f);
if (flags & DIRTY_BITMAP_MIG_EXTRA_FLAGS) {
flags = flags << 16 | qemu_get_be16(f);
}
}
return flags;
}
static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
{
/* The code currently does not send flags as more than one byte */
assert(!(flags & (0xffffff00 | DIRTY_BITMAP_MIG_EXTRA_FLAGS)));
qemu_put_byte(f, flags);
}
static void send_bitmap_header(QEMUFile *f, DBMSaveState *s,
SaveBitmapState *dbms, uint32_t additional_flags)
{
BlockDriverState *bs = dbms->bs;
BdrvDirtyBitmap *bitmap = dbms->bitmap;
uint32_t flags = additional_flags;
trace_send_bitmap_header_enter();
if (bs != s->prev_bs) {
s->prev_bs = bs;
flags |= DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME;
}
if (bitmap != s->prev_bitmap) {
s->prev_bitmap = bitmap;
flags |= DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME;
}
qemu_put_bitmap_flags(f, flags);
if (flags & DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME) {
qemu_put_counted_string(f, dbms->node_alias);
}
if (flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
qemu_put_counted_string(f, dbms->bitmap_alias);
}
}
static void send_bitmap_start(QEMUFile *f, DBMSaveState *s,
SaveBitmapState *dbms)
{
send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_START);
qemu_put_be32(f, bdrv_dirty_bitmap_granularity(dbms->bitmap));
qemu_put_byte(f, dbms->flags);
}
static void send_bitmap_complete(QEMUFile *f, DBMSaveState *s,
SaveBitmapState *dbms)
{
send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
}
static void send_bitmap_bits(QEMUFile *f, DBMSaveState *s,
SaveBitmapState *dbms,
uint64_t start_sector, uint32_t nr_sectors)
{
/* align for buffer_is_zero() */
uint64_t align = 4 * sizeof(long);
uint64_t unaligned_size =
bdrv_dirty_bitmap_serialization_size(
dbms->bitmap, start_sector << BDRV_SECTOR_BITS,
(uint64_t)nr_sectors << BDRV_SECTOR_BITS);
uint64_t buf_size = QEMU_ALIGN_UP(unaligned_size, align);
uint8_t *buf = g_malloc0(buf_size);
uint32_t flags = DIRTY_BITMAP_MIG_FLAG_BITS;
bdrv_dirty_bitmap_serialize_part(
dbms->bitmap, buf, start_sector << BDRV_SECTOR_BITS,
(uint64_t)nr_sectors << BDRV_SECTOR_BITS);
if (buffer_is_zero(buf, buf_size)) {
g_free(buf);
buf = NULL;
flags |= DIRTY_BITMAP_MIG_FLAG_ZEROES;
}
trace_send_bitmap_bits(flags, start_sector, nr_sectors, buf_size);
send_bitmap_header(f, s, dbms, flags);
qemu_put_be64(f, start_sector);
qemu_put_be32(f, nr_sectors);
/* if a block is zero we need to flush here since the network
* bandwidth is now a lot higher than the storage device bandwidth.
* thus if we queue zero blocks we slow down the migration. */
if (flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
qemu_fflush(f);
} else {
qemu_put_be64(f, buf_size);
qemu_put_buffer(f, buf, buf_size);
}
g_free(buf);
}
/* Called with iothread lock taken. */
static void dirty_bitmap_do_save_cleanup(DBMSaveState *s)
{
SaveBitmapState *dbms;
while ((dbms = QSIMPLEQ_FIRST(&s->dbms_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&s->dbms_list, entry);
bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
bdrv_unref(dbms->bs);
g_free(dbms->node_alias);
g_free(dbms->bitmap_alias);
g_free(dbms);
}
}
/* Called with iothread lock taken. */
static int add_bitmaps_to_list(DBMSaveState *s, BlockDriverState *bs,
const char *bs_name, GHashTable *alias_map)
{
BdrvDirtyBitmap *bitmap;
SaveBitmapState *dbms;
GHashTable *bitmap_aliases;
const char *node_alias, *bitmap_name, *bitmap_alias;
Error *local_err = NULL;
/* When an alias map is given, @bs_name must be @bs's node name */
assert(!alias_map || !strcmp(bs_name, bdrv_get_node_name(bs)));
FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
if (bdrv_dirty_bitmap_name(bitmap)) {
break;
}
}
if (!bitmap) {
return 0;
}
bitmap_name = bdrv_dirty_bitmap_name(bitmap);
if (!bs_name || strcmp(bs_name, "") == 0) {
error_report("Bitmap '%s' in unnamed node can't be migrated",
bitmap_name);
return -1;
}
if (alias_map) {
const AliasMapInnerNode *amin = g_hash_table_lookup(alias_map, bs_name);
if (!amin) {
/* Skip bitmaps on nodes with no alias */
return 0;
}
node_alias = amin->string;
bitmap_aliases = amin->subtree;
} else {
node_alias = bs_name;
bitmap_aliases = NULL;
}
if (node_alias[0] == '#') {
error_report("Bitmap '%s' in a node with auto-generated "
"name '%s' can't be migrated",
bitmap_name, node_alias);
return -1;
}
FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
BitmapMigrationBitmapAliasTransform *bitmap_transform = NULL;
bitmap_name = bdrv_dirty_bitmap_name(bitmap);
if (!bitmap_name) {
continue;
}
if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, &local_err)) {
error_report_err(local_err);
return -1;
}
if (bitmap_aliases) {
BitmapMigrationBitmapAlias *bmap_inner;
bmap_inner = g_hash_table_lookup(bitmap_aliases, bitmap_name);
if (!bmap_inner) {
/* Skip bitmaps with no alias */
continue;
}
bitmap_alias = bmap_inner->alias;
if (bmap_inner->has_transform) {
bitmap_transform = bmap_inner->transform;
}
} else {
if (strlen(bitmap_name) > UINT8_MAX) {
error_report("Cannot migrate bitmap '%s' on node '%s': "
"Name is longer than %u bytes",
bitmap_name, bs_name, UINT8_MAX);
return -1;
}
bitmap_alias = bitmap_name;
}
bdrv_ref(bs);
bdrv_dirty_bitmap_set_busy(bitmap, true);
dbms = g_new0(SaveBitmapState, 1);
dbms->bs = bs;
dbms->node_alias = g_strdup(node_alias);
dbms->bitmap_alias = g_strdup(bitmap_alias);
dbms->bitmap = bitmap;
dbms->total_sectors = bdrv_nb_sectors(bs);
dbms->sectors_per_chunk = CHUNK_SIZE * 8LLU *
(bdrv_dirty_bitmap_granularity(bitmap) >> BDRV_SECTOR_BITS);
assert(dbms->sectors_per_chunk != 0);
if (bdrv_dirty_bitmap_enabled(bitmap)) {
dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
}
if (bitmap_transform &&
bitmap_transform->has_persistent) {
if (bitmap_transform->persistent) {
dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
}
} else {
if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
}
}
QSIMPLEQ_INSERT_TAIL(&s->dbms_list, dbms, entry);
}
return 0;
}
/* Called with iothread lock taken. */
static int init_dirty_bitmap_migration(DBMSaveState *s)
{
BlockDriverState *bs;
SaveBitmapState *dbms;
GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL);
BlockBackend *blk;
const MigrationParameters *mig_params = &migrate_get_current()->parameters;
GHashTable *alias_map = NULL;
if (mig_params->has_block_bitmap_mapping) {
alias_map = construct_alias_map(mig_params->block_bitmap_mapping, true,
&error_abort);
}
s->bulk_completed = false;
s->prev_bs = NULL;
s->prev_bitmap = NULL;
s->no_bitmaps = false;
if (!alias_map) {
/*
* Use blockdevice name for direct (or filtered) children of named block
* backends.
*/
for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
const char *name = blk_name(blk);
if (!name || strcmp(name, "") == 0) {
continue;
}
bs = blk_bs(blk);
/* Skip filters without bitmaps */
while (bs && bs->drv && bs->drv->is_filter &&
!bdrv_has_named_bitmaps(bs))
{
bs = bdrv_filter_bs(bs);
}
if (bs && bs->drv && !bs->drv->is_filter) {
if (add_bitmaps_to_list(s, bs, name, NULL)) {
goto fail;
}
g_hash_table_add(handled_by_blk, bs);
}
}
}
for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
if (g_hash_table_contains(handled_by_blk, bs)) {
continue;
}
if (add_bitmaps_to_list(s, bs, bdrv_get_node_name(bs), alias_map)) {
goto fail;
}
}
/* unset migration flags here, to not roll back it */
QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
bdrv_dirty_bitmap_skip_store(dbms->bitmap, true);
}
if (QSIMPLEQ_EMPTY(&s->dbms_list)) {
s->no_bitmaps = true;
}
g_hash_table_destroy(handled_by_blk);
if (alias_map) {
g_hash_table_destroy(alias_map);
}
return 0;
fail:
g_hash_table_destroy(handled_by_blk);
if (alias_map) {
g_hash_table_destroy(alias_map);
}
dirty_bitmap_do_save_cleanup(s);
return -1;
}
/* Called with no lock taken. */
static void bulk_phase_send_chunk(QEMUFile *f, DBMSaveState *s,
SaveBitmapState *dbms)
{
uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
dbms->sectors_per_chunk);
send_bitmap_bits(f, s, dbms, dbms->cur_sector, nr_sectors);
dbms->cur_sector += nr_sectors;
if (dbms->cur_sector >= dbms->total_sectors) {
dbms->bulk_completed = true;
}
}
/* Called with no lock taken. */
static void bulk_phase(QEMUFile *f, DBMSaveState *s, bool limit)
{
SaveBitmapState *dbms;
QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
while (!dbms->bulk_completed) {
bulk_phase_send_chunk(f, s, dbms);
if (limit && qemu_file_rate_limit(f)) {
return;
}
}
}
s->bulk_completed = true;
}
/* for SaveVMHandlers */
static void dirty_bitmap_save_cleanup(void *opaque)
{
DBMSaveState *s = &((DBMState *)opaque)->save;
dirty_bitmap_do_save_cleanup(s);
}
static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
{
DBMSaveState *s = &((DBMState *)opaque)->save;
trace_dirty_bitmap_save_iterate(migration_in_postcopy());
if (migration_in_postcopy() && !s->bulk_completed) {
bulk_phase(f, s, true);
}
qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
return s->bulk_completed;
}
/* Called with iothread lock taken. */
static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
{
DBMSaveState *s = &((DBMState *)opaque)->save;
SaveBitmapState *dbms;
trace_dirty_bitmap_save_complete_enter();
if (!s->bulk_completed) {
bulk_phase(f, s, false);
}
QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
send_bitmap_complete(f, s, dbms);
}
qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
trace_dirty_bitmap_save_complete_finish();
dirty_bitmap_save_cleanup(opaque);
return 0;
}
static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
uint64_t max_size,
uint64_t *res_precopy_only,
uint64_t *res_compatible,
uint64_t *res_postcopy_only)
{
DBMSaveState *s = &((DBMState *)opaque)->save;
SaveBitmapState *dbms;
uint64_t pending = 0;
qemu_mutex_lock_iothread();
QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
uint64_t gran = bdrv_dirty_bitmap_granularity(dbms->bitmap);
uint64_t sectors = dbms->bulk_completed ? 0 :
dbms->total_sectors - dbms->cur_sector;
pending += DIV_ROUND_UP(sectors * BDRV_SECTOR_SIZE, gran);
}
qemu_mutex_unlock_iothread();
trace_dirty_bitmap_save_pending(pending, max_size);
*res_postcopy_only += pending;
}
/* First occurrence of this bitmap. It should be created if doesn't exist */
static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
{
Error *local_err = NULL;
uint32_t granularity = qemu_get_be32(f);
uint8_t flags = qemu_get_byte(f);
LoadBitmapState *b;
bool persistent;
if (s->cancelled) {
return 0;
}
if (s->bitmap) {
error_report("Bitmap with the same name ('%s') already exists on "
"destination", bdrv_dirty_bitmap_name(s->bitmap));
return -EINVAL;
} else {
s->bitmap = bdrv_create_dirty_bitmap(s->bs, granularity,
s->bitmap_name, &local_err);
if (!s->bitmap) {
error_report_err(local_err);
return -EINVAL;
}
}
if (flags & DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK) {
error_report("Unknown flags in migrated dirty bitmap header: %x",
flags);
return -EINVAL;
}
if (s->bmap_inner &&
s->bmap_inner->has_transform &&
s->bmap_inner->transform->has_persistent) {
persistent = s->bmap_inner->transform->persistent;
} else {
persistent = flags & DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
}
if (persistent) {
bdrv_dirty_bitmap_set_persistence(s->bitmap, true);
}
bdrv_disable_dirty_bitmap(s->bitmap);
if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
bdrv_dirty_bitmap_create_successor(s->bitmap, &local_err);
if (local_err) {
error_report_err(local_err);
return -EINVAL;
}
} else {
bdrv_dirty_bitmap_set_busy(s->bitmap, true);
}
b = g_new(LoadBitmapState, 1);
b->bs = s->bs;
b->bitmap = s->bitmap;
b->migrated = false;
b->enabled = flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
s->bitmaps = g_slist_prepend(s->bitmaps, b);
return 0;
}
/*
* before_vm_start_handle_item
*
* g_slist_foreach helper
*
* item is LoadBitmapState*
* opaque is DBMLoadState*
*/
static void before_vm_start_handle_item(void *item, void *opaque)
{
DBMLoadState *s = opaque;
LoadBitmapState *b = item;
if (b->enabled) {
if (b->migrated) {
bdrv_enable_dirty_bitmap(b->bitmap);
} else {
bdrv_dirty_bitmap_enable_successor(b->bitmap);
}
}
if (b->migrated) {
s->bitmaps = g_slist_remove(s->bitmaps, b);
g_free(b);
}
}
void dirty_bitmap_mig_before_vm_start(void)
{
DBMLoadState *s = &dbm_state.load;
qemu_mutex_lock(&s->lock);
assert(!s->before_vm_start_handled);
g_slist_foreach(s->bitmaps, before_vm_start_handle_item, s);
s->before_vm_start_handled = true;
qemu_mutex_unlock(&s->lock);
}
static void cancel_incoming_locked(DBMLoadState *s)
{
GSList *item;
if (s->cancelled) {
return;
}
s->cancelled = true;
s->bs = NULL;
s->bitmap = NULL;
/* Drop all unfinished bitmaps */
for (item = s->bitmaps; item; item = g_slist_next(item)) {
LoadBitmapState *b = item->data;
/*
* Bitmap must be unfinished, as finished bitmaps should already be
* removed from the list.
*/
assert(!s->before_vm_start_handled || !b->migrated);
if (bdrv_dirty_bitmap_has_successor(b->bitmap)) {
bdrv_reclaim_dirty_bitmap(b->bitmap, &error_abort);
} else {
bdrv_dirty_bitmap_set_busy(b->bitmap, false);
}
bdrv_release_dirty_bitmap(b->bitmap);
}
g_slist_free_full(s->bitmaps, g_free);
s->bitmaps = NULL;
}
void dirty_bitmap_mig_cancel_outgoing(void)
{
dirty_bitmap_do_save_cleanup(&dbm_state.save);
}
void dirty_bitmap_mig_cancel_incoming(void)
{
DBMLoadState *s = &dbm_state.load;
qemu_mutex_lock(&s->lock);
cancel_incoming_locked(s);
qemu_mutex_unlock(&s->lock);
}
static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
{
GSList *item;
trace_dirty_bitmap_load_complete();
if (s->cancelled) {
return;
}
bdrv_dirty_bitmap_deserialize_finish(s->bitmap);
if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
} else {
bdrv_dirty_bitmap_set_busy(s->bitmap, false);
}
for (item = s->bitmaps; item; item = g_slist_next(item)) {
LoadBitmapState *b = item->data;
if (b->bitmap == s->bitmap) {
b->migrated = true;
if (s->before_vm_start_handled) {
s->bitmaps = g_slist_remove(s->bitmaps, b);
g_free(b);
}
break;
}
}
}
static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
{
uint64_t first_byte = qemu_get_be64(f) << BDRV_SECTOR_BITS;
uint64_t nr_bytes = (uint64_t)qemu_get_be32(f) << BDRV_SECTOR_BITS;
trace_dirty_bitmap_load_bits_enter(first_byte >> BDRV_SECTOR_BITS,
nr_bytes >> BDRV_SECTOR_BITS);
if (s->flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
trace_dirty_bitmap_load_bits_zeroes();
if (!s->cancelled) {
bdrv_dirty_bitmap_deserialize_zeroes(s->bitmap, first_byte,
nr_bytes, false);
}
} else {
size_t ret;
g_autofree uint8_t *buf = NULL;
uint64_t buf_size = qemu_get_be64(f);
uint64_t needed_size;
/*
* The actual check for buf_size is done a bit later. We can't do it in
* cancelled mode as we don't have the bitmap to check the constraints
* (so, we allocate a buffer and read prior to the check). On the other
* hand, we shouldn't blindly g_malloc the number from the stream.
* Actually one chunk should not be larger than CHUNK_SIZE. Let's allow
* a bit larger (which means that bitmap migration will fail anyway and
* the whole migration will most probably fail soon due to broken
* stream).
*/
if (buf_size > 10 * CHUNK_SIZE) {
error_report("Bitmap migration stream buffer allocation request "
"is too large");
return -EIO;
}
buf = g_malloc(buf_size);
ret = qemu_get_buffer(f, buf, buf_size);
if (ret != buf_size) {
error_report("Failed to read bitmap bits");
return -EIO;
}
if (s->cancelled) {
return 0;
}
needed_size = bdrv_dirty_bitmap_serialization_size(s->bitmap,
first_byte,
nr_bytes);
if (needed_size > buf_size ||
buf_size > QEMU_ALIGN_UP(needed_size, 4 * sizeof(long))
/* Here used same alignment as in send_bitmap_bits */
) {
error_report("Migrated bitmap granularity doesn't "
"match the destination bitmap '%s' granularity",
bdrv_dirty_bitmap_name(s->bitmap));
cancel_incoming_locked(s);
return 0;
}
bdrv_dirty_bitmap_deserialize_part(s->bitmap, buf, first_byte, nr_bytes,
false);
}
return 0;
}
static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
GHashTable *alias_map)
{
GHashTable *bitmap_alias_map = NULL;
Error *local_err = NULL;
bool nothing;
s->flags = qemu_get_bitmap_flags(f);
trace_dirty_bitmap_load_header(s->flags);
nothing = s->flags == (s->flags & DIRTY_BITMAP_MIG_FLAG_EOS);
if (s->flags & DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME) {
if (!qemu_get_counted_string(f, s->node_alias)) {
error_report("Unable to read node alias string");
return -EINVAL;
}
if (!s->cancelled) {
if (alias_map) {
const AliasMapInnerNode *amin;
amin = g_hash_table_lookup(alias_map, s->node_alias);
if (!amin) {
error_setg(&local_err, "Error: Unknown node alias '%s'",
s->node_alias);
s->bs = NULL;
} else {
bitmap_alias_map = amin->subtree;
s->bs = bdrv_lookup_bs(NULL, amin->string, &local_err);
}
} else {
s->bs = bdrv_lookup_bs(s->node_alias, s->node_alias,
&local_err);
}
if (!s->bs) {
error_report_err(local_err);
cancel_incoming_locked(s);
}
}
} else if (s->bs) {
if (alias_map) {
const AliasMapInnerNode *amin;
/* Must be present in the map, or s->bs would not be set */
amin = g_hash_table_lookup(alias_map, s->node_alias);
assert(amin != NULL);
bitmap_alias_map = amin->subtree;
}
} else if (!nothing && !s->cancelled) {
error_report("Error: block device name is not set");
cancel_incoming_locked(s);
}
assert(nothing || s->cancelled || !!alias_map == !!bitmap_alias_map);
if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
const char *bitmap_name;
if (!qemu_get_counted_string(f, s->bitmap_alias)) {
error_report("Unable to read bitmap alias string");
return -EINVAL;
}
bitmap_name = s->bitmap_alias;
if (!s->cancelled && bitmap_alias_map) {
BitmapMigrationBitmapAlias *bmap_inner;
bmap_inner = g_hash_table_lookup(bitmap_alias_map, s->bitmap_alias);
if (!bmap_inner) {
error_report("Error: Unknown bitmap alias '%s' on node "
"'%s' (alias '%s')", s->bitmap_alias,
s->bs->node_name, s->node_alias);
cancel_incoming_locked(s);
} else {
bitmap_name = bmap_inner->name;
}
s->bmap_inner = bmap_inner;
}
if (!s->cancelled) {
g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
/*
* bitmap may be NULL here, it wouldn't be an error if it is the
* first occurrence of the bitmap
*/
if (!s->bitmap && !(s->flags & DIRTY_BITMAP_MIG_FLAG_START)) {
error_report("Error: unknown dirty bitmap "
"'%s' for block device '%s'",
s->bitmap_name, s->bs->node_name);
cancel_incoming_locked(s);
}
}
} else if (!s->bitmap && !nothing && !s->cancelled) {
error_report("Error: block device name is not set");
cancel_incoming_locked(s);
}
return 0;
}
/*
* dirty_bitmap_load
*
* Load sequence of dirty bitmap chunks. Return error only on fatal io stream
* violations. On other errors just cancel bitmaps incoming migration and return
* 0.
*
* Note, than when incoming bitmap migration is canceled, we still must read all
* our chunks (and just ignore them), to not affect other migration objects.
*/
static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
{
GHashTable *alias_map = NULL;
const MigrationParameters *mig_params = &migrate_get_current()->parameters;
DBMLoadState *s = &((DBMState *)opaque)->load;
int ret = 0;
trace_dirty_bitmap_load_enter();
if (version_id != 1) {
QEMU_LOCK_GUARD(&s->lock);
cancel_incoming_locked(s);
return -EINVAL;
}
if (mig_params->has_block_bitmap_mapping) {
alias_map = construct_alias_map(mig_params->block_bitmap_mapping,
false, &error_abort);
}
do {
QEMU_LOCK_GUARD(&s->lock);
ret = dirty_bitmap_load_header(f, s, alias_map);
if (ret < 0) {
cancel_incoming_locked(s);
goto fail;
}
if (s->flags & DIRTY_BITMAP_MIG_FLAG_START) {
ret = dirty_bitmap_load_start(f, s);
} else if (s->flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
dirty_bitmap_load_complete(f, s);
} else if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
ret = dirty_bitmap_load_bits(f, s);
}
if (!ret) {
ret = qemu_file_get_error(f);
}
if (ret) {
cancel_incoming_locked(s);
goto fail;
}
} while (!(s->flags & DIRTY_BITMAP_MIG_FLAG_EOS));
trace_dirty_bitmap_load_success();
ret = 0;
fail:
if (alias_map) {
g_hash_table_destroy(alias_map);
}
return ret;
}
static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
{
DBMSaveState *s = &((DBMState *)opaque)->save;
SaveBitmapState *dbms = NULL;
if (init_dirty_bitmap_migration(s) < 0) {
return -1;
}
QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
send_bitmap_start(f, s, dbms);
}
qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
return 0;
}
static bool dirty_bitmap_is_active(void *opaque)
{
DBMSaveState *s = &((DBMState *)opaque)->save;
return migrate_dirty_bitmaps() && !s->no_bitmaps;
}
static bool dirty_bitmap_is_active_iterate(void *opaque)
{
return dirty_bitmap_is_active(opaque) && !runstate_is_running();
}
static bool dirty_bitmap_has_postcopy(void *opaque)
{
return true;
}
static SaveVMHandlers savevm_dirty_bitmap_handlers = {
.save_setup = dirty_bitmap_save_setup,
.save_live_complete_postcopy = dirty_bitmap_save_complete,
.save_live_complete_precopy = dirty_bitmap_save_complete,
.has_postcopy = dirty_bitmap_has_postcopy,
.save_live_pending = dirty_bitmap_save_pending,
.save_live_iterate = dirty_bitmap_save_iterate,
.is_active_iterate = dirty_bitmap_is_active_iterate,
.load_state = dirty_bitmap_load,
.save_cleanup = dirty_bitmap_save_cleanup,
.is_active = dirty_bitmap_is_active,
};
void dirty_bitmap_mig_init(void)
{
QSIMPLEQ_INIT(&dbm_state.save.dbms_list);
qemu_mutex_init(&dbm_state.load.lock);
register_savevm_live("dirty-bitmap", 0, 1,
&savevm_dirty_bitmap_handlers,
&dbm_state);
}
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