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Merge remote-tracking branch 'remotes/jnsnow/tags/bitmaps-pull-request' into staging

# gpg: Signature made Tue 13 Mar 2018 21:11:43 GMT
# gpg:                using RSA key 7DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/bitmaps-pull-request:
  iotests: add dirty bitmap postcopy test
  iotests: add dirty bitmap migration test
  migration: add postcopy migration of dirty bitmaps
  migration: allow qmp command migrate-start-postcopy for any postcopy
  migration: add is_active_iterate handler
  migration/qemu-file: add qemu_put_counted_string()
  migration: include migrate_dirty_bitmaps in migrate_postcopy
  qapi: add dirty-bitmaps migration capability
  migration: introduce postcopy-only pending
  dirty-bitmap: add locked state
  block/dirty-bitmap: add _locked version of bdrv_reclaim_dirty_bitmap
  block/dirty-bitmap: fix locking in bdrv_reclaim_dirty_bitmap
  block/dirty-bitmap: add bdrv_dirty_bitmap_enable_successor()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block/dirty-bitmap.c

@@ -40,6 +40,8 @@ struct BdrvDirtyBitmap {
     QemuMutex *mutex;
     HBitmap *bitmap;            /* Dirty bitmap implementation */
     HBitmap *meta;              /* Meta dirty bitmap */
+    bool qmp_locked;            /* Bitmap is locked, it can't be modified
+                                   through QMP */
     BdrvDirtyBitmap *successor; /* Anonymous child; implies frozen status */
     char *name;                 /* Optional non-empty unique ID */
     int64_t size;               /* Size of the bitmap, in bytes */
@@ -183,6 +185,18 @@ bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
     return bitmap->successor;
 }
 
+void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked)
+{
+    qemu_mutex_lock(bitmap->mutex);
+    bitmap->qmp_locked = qmp_locked;
+    qemu_mutex_unlock(bitmap->mutex);
+}
+
+bool bdrv_dirty_bitmap_qmp_locked(BdrvDirtyBitmap *bitmap)
+{
+    return bitmap->qmp_locked;
+}
+
 /* Called with BQL taken.  */
 bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap)
 {
@@ -194,6 +208,8 @@ DirtyBitmapStatus bdrv_dirty_bitmap_status(BdrvDirtyBitmap *bitmap)
 {
     if (bdrv_dirty_bitmap_frozen(bitmap)) {
         return DIRTY_BITMAP_STATUS_FROZEN;
+    } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
+        return DIRTY_BITMAP_STATUS_LOCKED;
     } else if (!bdrv_dirty_bitmap_enabled(bitmap)) {
         return DIRTY_BITMAP_STATUS_DISABLED;
     } else {
@@ -234,6 +250,59 @@ int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
     return 0;
 }
 
+/* Called with BQL taken. */
+void bdrv_dirty_bitmap_enable_successor(BdrvDirtyBitmap *bitmap)
+{
+    qemu_mutex_lock(bitmap->mutex);
+    bdrv_enable_dirty_bitmap(bitmap->successor);
+    qemu_mutex_unlock(bitmap->mutex);
+}
+
+/* Called within bdrv_dirty_bitmap_lock..unlock */
+static void bdrv_do_release_matching_dirty_bitmap_locked(
+    BlockDriverState *bs, BdrvDirtyBitmap *bitmap,
+    bool (*cond)(BdrvDirtyBitmap *bitmap))
+{
+    BdrvDirtyBitmap *bm, *next;
+
+    QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
+        if ((!bitmap || bm == bitmap) && (!cond || cond(bm))) {
+            assert(!bm->active_iterators);
+            assert(!bdrv_dirty_bitmap_frozen(bm));
+            assert(!bm->meta);
+            QLIST_REMOVE(bm, list);
+            hbitmap_free(bm->bitmap);
+            g_free(bm->name);
+            g_free(bm);
+
+            if (bitmap) {
+                return;
+            }
+        }
+    }
+
+    if (bitmap) {
+        abort();
+    }
+}
+
+/* Called with BQL taken.  */
+static void bdrv_do_release_matching_dirty_bitmap(
+    BlockDriverState *bs, BdrvDirtyBitmap *bitmap,
+    bool (*cond)(BdrvDirtyBitmap *bitmap))
+{
+    bdrv_dirty_bitmaps_lock(bs);
+    bdrv_do_release_matching_dirty_bitmap_locked(bs, bitmap, cond);
+    bdrv_dirty_bitmaps_unlock(bs);
+}
+
+/* Called within bdrv_dirty_bitmap_lock..unlock */
+static void bdrv_release_dirty_bitmap_locked(BlockDriverState *bs,
+                                             BdrvDirtyBitmap *bitmap)
+{
+    bdrv_do_release_matching_dirty_bitmap_locked(bs, bitmap, NULL);
+}
+
 /**
  * For a bitmap with a successor, yield our name to the successor,
  * delete the old bitmap, and return a handle to the new bitmap.
@@ -267,11 +336,11 @@ BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
  * In cases of failure where we can no longer safely delete the parent,
  * we may wish to re-join the parent and child/successor.
  * The merged parent will be un-frozen, but not explicitly re-enabled.
- * Called with BQL taken.
+ * Called within bdrv_dirty_bitmap_lock..unlock and with BQL taken.
  */
-BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
+BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
-                                           BdrvDirtyBitmap *parent,
+                                                  BdrvDirtyBitmap *parent,
-                                           Error **errp)
+                                                  Error **errp)
 {
     BdrvDirtyBitmap *successor = parent->successor;
 
@@ -284,12 +353,26 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
         error_setg(errp, "Merging of parent and successor bitmap failed");
         return NULL;
     }
-    bdrv_release_dirty_bitmap(bs, successor);
+    bdrv_release_dirty_bitmap_locked(bs, successor);
     parent->successor = NULL;
 
     return parent;
 }
 
+/* Called with BQL taken. */
+BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
+                                           BdrvDirtyBitmap *parent,
+                                           Error **errp)
+{
+    BdrvDirtyBitmap *ret;
+
+    qemu_mutex_lock(parent->mutex);
+    ret = bdrv_reclaim_dirty_bitmap_locked(bs, parent, errp);
+    qemu_mutex_unlock(parent->mutex);
+
+    return ret;
+}
+
 /**
  * Truncates _all_ bitmaps attached to a BDS.
  * Called with BQL taken.
@@ -313,36 +396,6 @@ static bool bdrv_dirty_bitmap_has_name(BdrvDirtyBitmap *bitmap)
     return !!bdrv_dirty_bitmap_name(bitmap);
 }
 
-/* Called with BQL taken.  */
-static void bdrv_do_release_matching_dirty_bitmap(
-    BlockDriverState *bs, BdrvDirtyBitmap *bitmap,
-    bool (*cond)(BdrvDirtyBitmap *bitmap))
-{
-    BdrvDirtyBitmap *bm, *next;
-    bdrv_dirty_bitmaps_lock(bs);
-    QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
-        if ((!bitmap || bm == bitmap) && (!cond || cond(bm))) {
-            assert(!bm->active_iterators);
-            assert(!bdrv_dirty_bitmap_frozen(bm));
-            assert(!bm->meta);
-            QLIST_REMOVE(bm, list);
-            hbitmap_free(bm->bitmap);
-            g_free(bm->name);
-            g_free(bm);
-
-            if (bitmap) {
-                goto out;
-            }
-        }
-    }
-    if (bitmap) {
-        abort();
-    }
-
-out:
-    bdrv_dirty_bitmaps_unlock(bs);
-}
-
 /* Called with BQL taken.  */
 void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
 {

blockdev.c

@@ -2118,6 +2118,9 @@ static void block_dirty_bitmap_clear_prepare(BlkActionState *common,
     if (bdrv_dirty_bitmap_frozen(state->bitmap)) {
         error_setg(errp, "Cannot modify a frozen bitmap");
         return;
+    } else if (bdrv_dirty_bitmap_qmp_locked(state->bitmap)) {
+        error_setg(errp, "Cannot modify a locked bitmap");
+        return;
     } else if (!bdrv_dirty_bitmap_enabled(state->bitmap)) {
         error_setg(errp, "Cannot clear a disabled bitmap");
         return;
@@ -2862,6 +2865,11 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
                    "Bitmap '%s' is currently frozen and cannot be removed",
                    name);
         return;
+    } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
+        error_setg(errp,
+                   "Bitmap '%s' is currently locked and cannot be removed",
+                   name);
+        return;
     }
 
     if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
@@ -2896,6 +2904,11 @@ void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
                    "Bitmap '%s' is currently frozen and cannot be modified",
                    name);
         return;
+    } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
+        error_setg(errp,
+                   "Bitmap '%s' is currently locked and cannot be modified",
+                   name);
+        return;
     } else if (!bdrv_dirty_bitmap_enabled(bitmap)) {
         error_setg(errp,
                    "Bitmap '%s' is currently disabled and cannot be cleared",
@@ -3370,6 +3383,12 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn,
             bdrv_unref(target_bs);
             goto out;
         }
+        if (bdrv_dirty_bitmap_qmp_locked(bmap)) {
+            error_setg(errp,
+                       "Bitmap '%s' is currently locked and cannot be used for "
+                       "backup", backup->bitmap);
+            goto out;
+        }
     }
 
     job = backup_job_create(backup->job_id, bs, target_bs, backup->speed,

hw/s390x/s390-stattrib.c

@@ -183,15 +183,16 @@ static int cmma_save_setup(QEMUFile *f, void *opaque)
 }
 
 static void cmma_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
-                             uint64_t *non_postcopiable_pending,
+                              uint64_t *res_precopy_only,
-                             uint64_t *postcopiable_pending)
+                              uint64_t *res_compatible,
+                              uint64_t *res_postcopy_only)
 {
     S390StAttribState *sas = S390_STATTRIB(opaque);
     S390StAttribClass *sac = S390_STATTRIB_GET_CLASS(sas);
     long long res = sac->get_dirtycount(sas);
 
     if (res >= 0) {
-        *non_postcopiable_pending += res;
+        *res_precopy_only += res;
     }
 }
 

include/block/dirty-bitmap.h

@@ -21,6 +21,7 @@ BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
 BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
                                            BdrvDirtyBitmap *bitmap,
                                            Error **errp);
+void bdrv_dirty_bitmap_enable_successor(BdrvDirtyBitmap *bitmap);
 BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
                                         const char *name);
 void bdrv_dirty_bitmap_make_anon(BdrvDirtyBitmap *bitmap);
@@ -68,6 +69,8 @@ void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap *bitmap);
 void bdrv_dirty_bitmap_set_readonly(BdrvDirtyBitmap *bitmap, bool value);
 void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap,
                                        bool persistent);
+void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked);
+
 
 /* Functions that require manual locking.  */
 void bdrv_dirty_bitmap_lock(BdrvDirtyBitmap *bitmap);
@@ -87,10 +90,14 @@ bool bdrv_dirty_bitmap_readonly(const BdrvDirtyBitmap *bitmap);
 bool bdrv_has_readonly_bitmaps(BlockDriverState *bs);
 bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap *bitmap);
+bool bdrv_dirty_bitmap_qmp_locked(BdrvDirtyBitmap *bitmap);
 bool bdrv_has_changed_persistent_bitmaps(BlockDriverState *bs);
 BdrvDirtyBitmap *bdrv_dirty_bitmap_next(BlockDriverState *bs,
                                         BdrvDirtyBitmap *bitmap);
 char *bdrv_dirty_bitmap_sha256(const BdrvDirtyBitmap *bitmap, Error **errp);
 int64_t bdrv_dirty_bitmap_next_zero(BdrvDirtyBitmap *bitmap, uint64_t start);
+BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
+                                                  BdrvDirtyBitmap *bitmap,
+                                                  Error **errp);
 
 #endif

include/migration/misc.h

@@ -56,4 +56,7 @@ bool migration_has_failed(MigrationState *);
 bool migration_in_postcopy_after_devices(MigrationState *);
 void migration_global_dump(Monitor *mon);
 
+/* migration/block-dirty-bitmap.c */
+void dirty_bitmap_mig_init(void);
+
 #endif

include/migration/register.h

@@ -26,6 +26,15 @@ typedef struct SaveVMHandlers {
     bool (*is_active)(void *opaque);
     bool (*has_postcopy)(void *opaque);
 
+    /* is_active_iterate
+     * If it is not NULL then qemu_savevm_state_iterate will skip iteration if
+     * it returns false. For example, it is needed for only-postcopy-states,
+     * which needs to be handled by qemu_savevm_state_setup and
+     * qemu_savevm_state_pending, but do not need iterations until not in
+     * postcopy stage.
+     */
+    bool (*is_active_iterate)(void *opaque);
+
     /* This runs outside the iothread lock in the migration case, and
      * within the lock in the savevm case.  The callback had better only
      * use data that is local to the migration thread or protected
@@ -37,8 +46,21 @@ typedef struct SaveVMHandlers {
     int (*save_setup)(QEMUFile *f, void *opaque);
     void (*save_live_pending)(QEMUFile *f, void *opaque,
                               uint64_t threshold_size,
-                              uint64_t *non_postcopiable_pending,
+                              uint64_t *res_precopy_only,
-                              uint64_t *postcopiable_pending);
+                              uint64_t *res_compatible,
+                              uint64_t *res_postcopy_only);
+    /* Note for save_live_pending:
+     * - res_precopy_only is for data which must be migrated in precopy phase
+     *     or in stopped state, in other words - before target vm start
+     * - res_compatible is for data which may be migrated in any phase
+     * - res_postcopy_only is for data which must be migrated in postcopy phase
+     *     or in stopped state, in other words - after source vm stop
+     *
+     * Sum of res_postcopy_only, res_compatible and res_postcopy_only is the
+     * whole amount of pending data.
+     */
+
+
     LoadStateHandler *load_state;
     int (*load_setup)(QEMUFile *f, void *opaque);
     int (*load_cleanup)(void *opaque);

migration/Makefile.objs

@@ -6,6 +6,7 @@ common-obj-y += qemu-file.o global_state.o
 common-obj-y += qemu-file-channel.o
 common-obj-y += xbzrle.o postcopy-ram.o
 common-obj-y += qjson.o
+common-obj-y += block-dirty-bitmap.o
 
 common-obj-$(CONFIG_RDMA) += rdma.o
 

migration/block-dirty-bitmap.c

@@ -0,0 +1,746 @@
+/*
+ * 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 name size ] \  flags & DEVICE_NAME
+ * [ n bytes: node name     ] /
+ * [ 1 byte: bitmap name size ] \  flags & BITMAP_NAME
+ * [ n bytes: bitmap name     ] /
+ *
+ * # 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 "qemu/main-loop.h"
+#include "qemu/error-report.h"
+#include "migration/misc.h"
+#include "migration/migration.h"
+#include "migration/qemu-file.h"
+#include "migration/vmstate.h"
+#include "migration/register.h"
+#include "qemu/hbitmap.h"
+#include "sysemu/sysemu.h"
+#include "qemu/cutils.h"
+#include "qapi/error.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 elder versions, no it is ignored */
+#define DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK    0xf8
+
+typedef struct DirtyBitmapMigBitmapState {
+    /* Written during setup phase. */
+    BlockDriverState *bs;
+    const char *node_name;
+    BdrvDirtyBitmap *bitmap;
+    uint64_t total_sectors;
+    uint64_t sectors_per_chunk;
+    QSIMPLEQ_ENTRY(DirtyBitmapMigBitmapState) entry;
+    uint8_t flags;
+
+    /* For bulk phase. */
+    bool bulk_completed;
+    uint64_t cur_sector;
+} DirtyBitmapMigBitmapState;
+
+typedef struct DirtyBitmapMigState {
+    QSIMPLEQ_HEAD(dbms_list, DirtyBitmapMigBitmapState) dbms_list;
+
+    bool bulk_completed;
+    bool no_bitmaps;
+
+    /* for send_bitmap_bits() */
+    BlockDriverState *prev_bs;
+    BdrvDirtyBitmap *prev_bitmap;
+} DirtyBitmapMigState;
+
+typedef struct DirtyBitmapLoadState {
+    uint32_t flags;
+    char node_name[256];
+    char bitmap_name[256];
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+} DirtyBitmapLoadState;
+
+static DirtyBitmapMigState dirty_bitmap_mig_state;
+
+typedef struct DirtyBitmapLoadBitmapState {
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    bool migrated;
+} DirtyBitmapLoadBitmapState;
+static GSList *enabled_bitmaps;
+QemuMutex finish_lock;
+
+void init_dirty_bitmap_incoming_migration(void)
+{
+    qemu_mutex_init(&finish_lock);
+}
+
+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 do not send flags more than one byte */
+    assert(!(flags & (0xffffff00 | DIRTY_BITMAP_MIG_EXTRA_FLAGS)));
+
+    qemu_put_byte(f, flags);
+}
+
+static void send_bitmap_header(QEMUFile *f, DirtyBitmapMigBitmapState *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 != dirty_bitmap_mig_state.prev_bs) {
+        dirty_bitmap_mig_state.prev_bs = bs;
+        flags |= DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME;
+    }
+
+    if (bitmap != dirty_bitmap_mig_state.prev_bitmap) {
+        dirty_bitmap_mig_state.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_name);
+    }
+
+    if (flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
+        qemu_put_counted_string(f, bdrv_dirty_bitmap_name(bitmap));
+    }
+}
+
+static void send_bitmap_start(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
+{
+    send_bitmap_header(f, 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, DirtyBitmapMigBitmapState *dbms)
+{
+    send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
+}
+
+static void send_bitmap_bits(QEMUFile *f, DirtyBitmapMigBitmapState *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, 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_mig_cleanup(void)
+{
+    DirtyBitmapMigBitmapState *dbms;
+
+    while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
+        QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
+        bdrv_dirty_bitmap_set_qmp_locked(dbms->bitmap, false);
+        bdrv_unref(dbms->bs);
+        g_free(dbms);
+    }
+}
+
+/* Called with iothread lock taken. */
+static int init_dirty_bitmap_migration(void)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    DirtyBitmapMigBitmapState *dbms;
+    BdrvNextIterator it;
+
+    dirty_bitmap_mig_state.bulk_completed = false;
+    dirty_bitmap_mig_state.prev_bs = NULL;
+    dirty_bitmap_mig_state.prev_bitmap = NULL;
+    dirty_bitmap_mig_state.no_bitmaps = false;
+
+    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+        const char *drive_name = bdrv_get_device_or_node_name(bs);
+
+        /* skip automatically inserted nodes */
+        while (bs && bs->drv && bs->implicit) {
+            bs = backing_bs(bs);
+        }
+
+        for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap;
+             bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
+        {
+            if (!bdrv_dirty_bitmap_name(bitmap)) {
+                continue;
+            }
+
+            if (drive_name == NULL) {
+                error_report("Found bitmap '%s' in unnamed node %p. It can't "
+                             "be migrated", bdrv_dirty_bitmap_name(bitmap), bs);
+                goto fail;
+            }
+
+            if (bdrv_dirty_bitmap_frozen(bitmap)) {
+                error_report("Can't migrate frozen dirty bitmap: '%s",
+                             bdrv_dirty_bitmap_name(bitmap));
+                goto fail;
+            }
+
+            if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
+                error_report("Can't migrate locked dirty bitmap: '%s",
+                             bdrv_dirty_bitmap_name(bitmap));
+                goto fail;
+            }
+
+            bdrv_ref(bs);
+            bdrv_dirty_bitmap_set_qmp_locked(bitmap, true);
+
+            dbms = g_new0(DirtyBitmapMigBitmapState, 1);
+            dbms->bs = bs;
+            dbms->node_name = drive_name;
+            dbms->bitmap = bitmap;
+            dbms->total_sectors = bdrv_nb_sectors(bs);
+            dbms->sectors_per_chunk = CHUNK_SIZE * 8 *
+                bdrv_dirty_bitmap_granularity(bitmap) >> BDRV_SECTOR_BITS;
+            if (bdrv_dirty_bitmap_enabled(bitmap)) {
+                dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
+            }
+            if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
+                dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
+            }
+
+            QSIMPLEQ_INSERT_TAIL(&dirty_bitmap_mig_state.dbms_list,
+                                 dbms, entry);
+        }
+    }
+
+    /* unset persistance here, to not roll back it */
+    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+        bdrv_dirty_bitmap_set_persistance(dbms->bitmap, false);
+    }
+
+    if (QSIMPLEQ_EMPTY(&dirty_bitmap_mig_state.dbms_list)) {
+        dirty_bitmap_mig_state.no_bitmaps = true;
+    }
+
+    return 0;
+
+fail:
+    dirty_bitmap_mig_cleanup();
+
+    return -1;
+}
+
+/* Called with no lock taken.  */
+static void bulk_phase_send_chunk(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
+{
+    uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
+                             dbms->sectors_per_chunk);
+
+    send_bitmap_bits(f, 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, bool limit)
+{
+    DirtyBitmapMigBitmapState *dbms;
+
+    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+        while (!dbms->bulk_completed) {
+            bulk_phase_send_chunk(f, dbms);
+            if (limit && qemu_file_rate_limit(f)) {
+                return;
+            }
+        }
+    }
+
+    dirty_bitmap_mig_state.bulk_completed = true;
+}
+
+/* for SaveVMHandlers */
+static void dirty_bitmap_save_cleanup(void *opaque)
+{
+    dirty_bitmap_mig_cleanup();
+}
+
+static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
+{
+    trace_dirty_bitmap_save_iterate(migration_in_postcopy());
+
+    if (migration_in_postcopy() && !dirty_bitmap_mig_state.bulk_completed) {
+        bulk_phase(f, true);
+    }
+
+    qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
+
+    return dirty_bitmap_mig_state.bulk_completed;
+}
+
+/* Called with iothread lock taken.  */
+
+static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
+{
+    DirtyBitmapMigBitmapState *dbms;
+    trace_dirty_bitmap_save_complete_enter();
+
+    if (!dirty_bitmap_mig_state.bulk_completed) {
+        bulk_phase(f, false);
+    }
+
+    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+        send_bitmap_complete(f, dbms);
+    }
+
+    qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
+
+    trace_dirty_bitmap_save_complete_finish();
+
+    dirty_bitmap_mig_cleanup();
+    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)
+{
+    DirtyBitmapMigBitmapState *dbms;
+    uint64_t pending = 0;
+
+    qemu_mutex_lock_iothread();
+
+    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.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, DirtyBitmapLoadState *s)
+{
+    Error *local_err = NULL;
+    uint32_t granularity = qemu_get_be32(f);
+    uint8_t flags = qemu_get_byte(f);
+
+    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 (flags & DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT) {
+        bdrv_dirty_bitmap_set_persistance(s->bitmap, true);
+    }
+
+    bdrv_disable_dirty_bitmap(s->bitmap);
+    if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
+        DirtyBitmapLoadBitmapState *b;
+
+        bdrv_dirty_bitmap_create_successor(s->bs, s->bitmap, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return -EINVAL;
+        }
+
+        b = g_new(DirtyBitmapLoadBitmapState, 1);
+        b->bs = s->bs;
+        b->bitmap = s->bitmap;
+        b->migrated = false;
+        enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
+    }
+
+    return 0;
+}
+
+void dirty_bitmap_mig_before_vm_start(void)
+{
+    GSList *item;
+
+    qemu_mutex_lock(&finish_lock);
+
+    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+        DirtyBitmapLoadBitmapState *b = item->data;
+
+        if (b->migrated) {
+            bdrv_enable_dirty_bitmap(b->bitmap);
+        } else {
+            bdrv_dirty_bitmap_enable_successor(b->bitmap);
+        }
+
+        g_free(b);
+    }
+
+    g_slist_free(enabled_bitmaps);
+    enabled_bitmaps = NULL;
+
+    qemu_mutex_unlock(&finish_lock);
+}
+
+static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
+{
+    GSList *item;
+    trace_dirty_bitmap_load_complete();
+    bdrv_dirty_bitmap_deserialize_finish(s->bitmap);
+
+    qemu_mutex_lock(&finish_lock);
+
+    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+        DirtyBitmapLoadBitmapState *b = item->data;
+
+        if (b->bitmap == s->bitmap) {
+            b->migrated = true;
+            break;
+        }
+    }
+
+    if (bdrv_dirty_bitmap_frozen(s->bitmap)) {
+        bdrv_dirty_bitmap_lock(s->bitmap);
+        if (enabled_bitmaps == NULL) {
+            /* in postcopy */
+            bdrv_reclaim_dirty_bitmap_locked(s->bs, s->bitmap, &error_abort);
+            bdrv_enable_dirty_bitmap(s->bitmap);
+        } else {
+            /* target not started, successor must be empty */
+            int64_t count = bdrv_get_dirty_count(s->bitmap);
+            BdrvDirtyBitmap *ret = bdrv_reclaim_dirty_bitmap_locked(s->bs,
+                                                                    s->bitmap,
+                                                                    NULL);
+            /* bdrv_reclaim_dirty_bitmap can fail only on no successor (it
+             * must be) or on merge fail, but merge can't fail when second
+             * bitmap is empty
+             */
+            assert(ret == s->bitmap &&
+                   count == bdrv_get_dirty_count(s->bitmap));
+        }
+        bdrv_dirty_bitmap_unlock(s->bitmap);
+    }
+
+    qemu_mutex_unlock(&finish_lock);
+}
+
+static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *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();
+        bdrv_dirty_bitmap_deserialize_zeroes(s->bitmap, first_byte, nr_bytes,
+                                             false);
+    } else {
+        size_t ret;
+        uint8_t *buf;
+        uint64_t buf_size = qemu_get_be64(f);
+        uint64_t 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));
+            return -EINVAL;
+        }
+
+        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;
+        }
+
+        bdrv_dirty_bitmap_deserialize_part(s->bitmap, buf, first_byte, nr_bytes,
+                                           false);
+        g_free(buf);
+    }
+
+    return 0;
+}
+
+static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
+{
+    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_name)) {
+            error_report("Unable to read node name string");
+            return -EINVAL;
+        }
+        s->bs = bdrv_lookup_bs(s->node_name, s->node_name, &local_err);
+        if (!s->bs) {
+            error_report_err(local_err);
+            return -EINVAL;
+        }
+    } else if (!s->bs && !nothing) {
+        error_report("Error: block device name is not set");
+        return -EINVAL;
+    }
+
+    if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
+        if (!qemu_get_counted_string(f, s->bitmap_name)) {
+            error_report("Unable to read bitmap name string");
+            return -EINVAL;
+        }
+        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->node_name);
+            return -EINVAL;
+        }
+    } else if (!s->bitmap && !nothing) {
+        error_report("Error: block device name is not set");
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
+{
+    static DirtyBitmapLoadState s;
+    int ret = 0;
+
+    trace_dirty_bitmap_load_enter();
+
+    if (version_id != 1) {
+        return -EINVAL;
+    }
+
+    do {
+        ret = dirty_bitmap_load_header(f, &s);
+
+        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) {
+            return ret;
+        }
+    } while (!(s.flags & DIRTY_BITMAP_MIG_FLAG_EOS));
+
+    trace_dirty_bitmap_load_success();
+    return 0;
+}
+
+static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
+{
+    DirtyBitmapMigBitmapState *dbms = NULL;
+    if (init_dirty_bitmap_migration() < 0) {
+        return -1;
+    }
+
+    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+        send_bitmap_start(f, dbms);
+    }
+    qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
+
+    return 0;
+}
+
+static bool dirty_bitmap_is_active(void *opaque)
+{
+    return migrate_dirty_bitmaps() && !dirty_bitmap_mig_state.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(&dirty_bitmap_mig_state.dbms_list);
+
+    register_savevm_live(NULL, "dirty-bitmap", 0, 1,
+                         &savevm_dirty_bitmap_handlers,
+                         &dirty_bitmap_mig_state);
+}

migration/block.c

@@ -864,8 +864,9 @@ static int block_save_complete(QEMUFile *f, void *opaque)
 }
 
 static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
-                               uint64_t *non_postcopiable_pending,
+                               uint64_t *res_precopy_only,
-                               uint64_t *postcopiable_pending)
+                               uint64_t *res_compatible,
+                               uint64_t *res_postcopy_only)
 {
     /* Estimate pending number of bytes to send */
     uint64_t pending;
@@ -886,7 +887,7 @@ static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
 
     DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
     /* We don't do postcopy */
-    *non_postcopiable_pending += pending;
+    *res_precopy_only += pending;
 }
 
 static int block_load(QEMUFile *f, void *opaque, int version_id)

migration/migration.c

@@ -157,6 +157,9 @@ MigrationIncomingState *migration_incoming_get_current(void)
         memset(&mis_current, 0, sizeof(MigrationIncomingState));
         qemu_mutex_init(&mis_current.rp_mutex);
         qemu_event_init(&mis_current.main_thread_load_event, false);
+
+        init_dirty_bitmap_incoming_migration();
+
         once = true;
     }
     return &mis_current;
@@ -320,6 +323,8 @@ static void process_incoming_migration_bh(void *opaque)
        state, we need to obey autostart. Any other state is set with
        runstate_set. */
 
+    dirty_bitmap_mig_before_vm_start();
+
     if (!global_state_received() ||
         global_state_get_runstate() == RUN_STATE_RUNNING) {
         if (autostart) {
@@ -1022,7 +1027,7 @@ void qmp_migrate_start_postcopy(Error **errp)
 {
     MigrationState *s = migrate_get_current();
 
-    if (!migrate_postcopy_ram()) {
+    if (!migrate_postcopy()) {
         error_setg(errp, "Enable postcopy with migrate_set_capability before"
                          " the start of migration");
         return;
@@ -1508,7 +1513,7 @@ bool migrate_postcopy_ram(void)
 
 bool migrate_postcopy(void)
 {
-    return migrate_postcopy_ram();
+    return migrate_postcopy_ram() || migrate_dirty_bitmaps();
 }
 
 bool migrate_auto_converge(void)
@@ -1565,6 +1570,15 @@ int migrate_decompress_threads(void)
     return s->parameters.decompress_threads;
 }
 
+bool migrate_dirty_bitmaps(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_DIRTY_BITMAPS];
+}
+
 bool migrate_use_events(void)
 {
     MigrationState *s;
@@ -2242,20 +2256,20 @@ typedef enum {
  */
 static MigIterateState migration_iteration_run(MigrationState *s)
 {
-    uint64_t pending_size, pend_post, pend_nonpost;
+    uint64_t pending_size, pend_pre, pend_compat, pend_post;
     bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
 
-    qemu_savevm_state_pending(s->to_dst_file, s->threshold_size,
+    qemu_savevm_state_pending(s->to_dst_file, s->threshold_size, &pend_pre,
-                              &pend_nonpost, &pend_post);
+                              &pend_compat, &pend_post);
-    pending_size = pend_nonpost + pend_post;
+    pending_size = pend_pre + pend_compat + pend_post;
 
     trace_migrate_pending(pending_size, s->threshold_size,
-                          pend_post, pend_nonpost);
+                          pend_pre, pend_compat, pend_post);
 
     if (pending_size && pending_size >= s->threshold_size) {
         /* Still a significant amount to transfer */
         if (migrate_postcopy() && !in_postcopy &&
-            pend_nonpost <= s->threshold_size &&
+            pend_pre <= s->threshold_size &&
             atomic_read(&s->start_postcopy)) {
             if (postcopy_start(s)) {
                 error_report("%s: postcopy failed to start", __func__);

migration/migration.h

@@ -205,6 +205,7 @@ bool migrate_postcopy(void);
 bool migrate_release_ram(void);
 bool migrate_postcopy_ram(void);
 bool migrate_zero_blocks(void);
+bool migrate_dirty_bitmaps(void);
 
 bool migrate_auto_converge(void);
 bool migrate_use_multifd(void);
@@ -234,4 +235,7 @@ void migrate_send_rp_pong(MigrationIncomingState *mis,
 int migrate_send_rp_req_pages(MigrationIncomingState *mis, const char* rbname,
                               ram_addr_t start, size_t len);
 
+void dirty_bitmap_mig_before_vm_start(void);
+void init_dirty_bitmap_incoming_migration(void);
+
 #endif

migration/qemu-file.c

@@ -733,6 +733,19 @@ size_t qemu_get_counted_string(QEMUFile *f, char buf[256])
     return res == len ? res : 0;
 }
 
+/*
+ * Put a string with one preceding byte containing its length. The length of
+ * the string should be less than 256.
+ */
+void qemu_put_counted_string(QEMUFile *f, const char *str)
+{
+    size_t len = strlen(str);
+
+    assert(len < 256);
+    qemu_put_byte(f, len);
+    qemu_put_buffer(f, (const uint8_t *)str, len);
+}
+
 /*
  * Set the blocking state of the QEMUFile.
  * Note: On some transports the OS only keeps a single blocking state for

migration/qemu-file.h

@@ -174,4 +174,6 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
                              ram_addr_t offset, size_t size,
                              uint64_t *bytes_sent);
 
+void qemu_put_counted_string(QEMUFile *f, const char *name);
+
 #endif

migration/ram.c

@@ -2370,8 +2370,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
 }
 
 static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
-                             uint64_t *non_postcopiable_pending,
+                             uint64_t *res_precopy_only,
-                             uint64_t *postcopiable_pending)
+                             uint64_t *res_compatible,
+                             uint64_t *res_postcopy_only)
 {
     RAMState **temp = opaque;
     RAMState *rs = *temp;
@@ -2391,9 +2392,9 @@ static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
 
     if (migrate_postcopy_ram()) {
         /* We can do postcopy, and all the data is postcopiable */
-        *postcopiable_pending += remaining_size;
+        *res_compatible += remaining_size;
     } else {
-        *non_postcopiable_pending += remaining_size;
+        *res_precopy_only += remaining_size;
     }
 }
 

migration/savevm.c

@@ -1029,6 +1029,11 @@ int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy)
                 continue;
             }
         }
+        if (se->ops && se->ops->is_active_iterate) {
+            if (!se->ops->is_active_iterate(se->opaque)) {
+                continue;
+            }
+        }
         /*
          * In the postcopy phase, any device that doesn't know how to
          * do postcopy should have saved it's state in the _complete
@@ -1221,13 +1226,15 @@ int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
  * for units that can't do postcopy.
  */
 void qemu_savevm_state_pending(QEMUFile *f, uint64_t threshold_size,
-                               uint64_t *res_non_postcopiable,
+                               uint64_t *res_precopy_only,
-                               uint64_t *res_postcopiable)
+                               uint64_t *res_compatible,
+                               uint64_t *res_postcopy_only)
 {
     SaveStateEntry *se;
 
-    *res_non_postcopiable = 0;
+    *res_precopy_only = 0;
-    *res_postcopiable = 0;
+    *res_compatible = 0;
+    *res_postcopy_only = 0;
 
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
@@ -1240,7 +1247,8 @@ void qemu_savevm_state_pending(QEMUFile *f, uint64_t threshold_size,
             }
         }
         se->ops->save_live_pending(f, se->opaque, threshold_size,
-                                   res_non_postcopiable, res_postcopiable);
+                                   res_precopy_only, res_compatible,
+                                   res_postcopy_only);
     }
 }
 
@@ -1686,6 +1694,8 @@ static void loadvm_postcopy_handle_run_bh(void *opaque)
 
     trace_loadvm_postcopy_handle_run_vmstart();
 
+    dirty_bitmap_mig_before_vm_start();
+
     if (autostart) {
         /* Hold onto your hats, starting the CPU */
         vm_start();

migration/savevm.h

@@ -38,8 +38,9 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f);
 int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
                                        bool inactivate_disks);
 void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
-                               uint64_t *res_non_postcopiable,
+                               uint64_t *res_precopy_only,
-                               uint64_t *res_postcopiable);
+                               uint64_t *res_compatible,
+                               uint64_t *res_postcopy_only);
 void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
 void qemu_savevm_send_open_return_path(QEMUFile *f);
 int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);

migration/trace-events

@@ -86,7 +86,7 @@ migrate_fd_cleanup(void) ""
 migrate_fd_error(const char *error_desc) "error=%s"
 migrate_fd_cancel(void) ""
 migrate_handle_rp_req_pages(const char *rbname, size_t start, size_t len) "in %s at 0x%zx len 0x%zx"
-migrate_pending(uint64_t size, uint64_t max, uint64_t post, uint64_t nonpost) "pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64 " nonpost=%" PRIu64 ")"
+migrate_pending(uint64_t size, uint64_t max, uint64_t pre, uint64_t compat, uint64_t post) "pending size %" PRIu64 " max %" PRIu64 " (pre = %" PRIu64 " compat=%" PRIu64 " post=%" PRIu64 ")"
 migrate_send_rp_message(int msg_type, uint16_t len) "%d: len %d"
 migration_completion_file_err(void) ""
 migration_completion_postcopy_end(void) ""
@@ -227,3 +227,17 @@ colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'"
 colo_send_message(const char *msg) "Send '%s' message"
 colo_receive_message(const char *msg) "Receive '%s' message"
 colo_failover_set_state(const char *new_state) "new state %s"
+
+# migration/block-dirty-bitmap.c
+send_bitmap_header_enter(void) ""
+send_bitmap_bits(uint32_t flags, uint64_t start_sector, uint32_t nr_sectors, uint64_t data_size) "flags: 0x%x, start_sector: %" PRIu64 ", nr_sectors: %" PRIu32 ", data_size: %" PRIu64
+dirty_bitmap_save_iterate(int in_postcopy) "in postcopy: %d"
+dirty_bitmap_save_complete_enter(void) ""
+dirty_bitmap_save_complete_finish(void) ""
+dirty_bitmap_save_pending(uint64_t pending, uint64_t max_size) "pending %" PRIu64 " max: %" PRIu64
+dirty_bitmap_load_complete(void) ""
+dirty_bitmap_load_bits_enter(uint64_t first_sector, uint32_t nr_sectors) "chunk: %" PRIu64 " %" PRIu32
+dirty_bitmap_load_bits_zeroes(void) ""
+dirty_bitmap_load_header(uint32_t flags) "flags 0x%x"
+dirty_bitmap_load_enter(void) ""
+dirty_bitmap_load_success(void) ""

qapi/block-core.json

@@ -426,10 +426,13 @@
 # @active: The bitmap is actively monitoring for new writes, and can be cleared,
 #          deleted, or used for backup operations.
 #
+# @locked: The bitmap is currently in-use by some operation and can not be
+#          cleared, deleted, or used for backup operations. (Since 2.12)
+#
 # Since: 2.4
 ##
 { 'enum': 'DirtyBitmapStatus',
-  'data': ['active', 'disabled', 'frozen'] }
+  'data': ['active', 'disabled', 'frozen', 'locked'] }
 
 ##
 # @BlockDirtyInfo:

qapi/migration.json

@@ -354,12 +354,16 @@
 #
 # @x-multifd: Use more than one fd for migration (since 2.11)
 #
+# @dirty-bitmaps: If enabled, QEMU will migrate named dirty bitmaps.
+#                 (since 2.12)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
            'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
-           'block', 'return-path', 'pause-before-switchover', 'x-multifd' ] }
+           'block', 'return-path', 'pause-before-switchover', 'x-multifd',
+           'dirty-bitmaps' ] }
 
 ##
 # @MigrationCapabilityStatus:

tests/qemu-iotests/169

@@ -0,0 +1,156 @@
+#!/usr/bin/env python
+#
+# Tests for dirty bitmaps migration.
+#
+# Copyright (c) 2016-2017 Virtuozzo International GmbH. All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import os
+import iotests
+import time
+import itertools
+import operator
+import new
+from iotests import qemu_img
+
+
+disk_a = os.path.join(iotests.test_dir, 'disk_a')
+disk_b = os.path.join(iotests.test_dir, 'disk_b')
+size = '1M'
+mig_file = os.path.join(iotests.test_dir, 'mig_file')
+
+
+class TestDirtyBitmapMigration(iotests.QMPTestCase):
+    def tearDown(self):
+        self.vm_a.shutdown()
+        self.vm_b.shutdown()
+        os.remove(disk_a)
+        os.remove(disk_b)
+        os.remove(mig_file)
+
+    def setUp(self):
+        qemu_img('create', '-f', iotests.imgfmt, disk_a, size)
+        qemu_img('create', '-f', iotests.imgfmt, disk_b, size)
+
+        self.vm_a = iotests.VM(path_suffix='a').add_drive(disk_a)
+        self.vm_a.launch()
+
+        self.vm_b = iotests.VM(path_suffix='b')
+        self.vm_b.add_incoming("exec: cat '" + mig_file + "'")
+
+    def add_bitmap(self, vm, granularity, persistent):
+        params = {'node': 'drive0',
+                  'name': 'bitmap0',
+                  'granularity': granularity}
+        if persistent:
+            params['persistent'] = True
+            params['autoload'] = True
+
+        result = vm.qmp('block-dirty-bitmap-add', **params)
+        self.assert_qmp(result, 'return', {});
+
+    def get_bitmap_hash(self, vm):
+        result = vm.qmp('x-debug-block-dirty-bitmap-sha256',
+                        node='drive0', name='bitmap0')
+        return result['return']['sha256']
+
+    def check_bitmap(self, vm, sha256):
+        result = vm.qmp('x-debug-block-dirty-bitmap-sha256',
+                        node='drive0', name='bitmap0')
+        if sha256:
+            self.assert_qmp(result, 'return/sha256', sha256);
+        else:
+            self.assert_qmp(result, 'error/desc',
+                            "Dirty bitmap 'bitmap0' not found");
+
+    def do_test_migration(self, persistent, migrate_bitmaps, online,
+                          shared_storage):
+        granularity = 512
+
+        # regions = ((start, count), ...)
+        regions = ((0, 0x10000),
+                   (0xf0000, 0x10000),
+                   (0xa0201, 0x1000))
+
+        should_migrate = migrate_bitmaps or persistent and shared_storage
+
+        self.vm_b.add_drive(disk_a if shared_storage else disk_b)
+
+        if online:
+            os.mkfifo(mig_file)
+            self.vm_b.launch()
+
+        self.add_bitmap(self.vm_a, granularity, persistent)
+        for r in regions:
+            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % r)
+        sha256 = self.get_bitmap_hash(self.vm_a)
+
+        if migrate_bitmaps:
+            capabilities = [{'capability': 'dirty-bitmaps', 'state': True}]
+
+            result = self.vm_a.qmp('migrate-set-capabilities',
+                                   capabilities=capabilities)
+            self.assert_qmp(result, 'return', {})
+
+            if online:
+                result = self.vm_b.qmp('migrate-set-capabilities',
+                                       capabilities=capabilities)
+                self.assert_qmp(result, 'return', {})
+
+        result = self.vm_a.qmp('migrate-set-capabilities',
+                               capabilities=[{'capability': 'events',
+                                              'state': True}])
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm_a.qmp('migrate', uri='exec:cat>' + mig_file)
+        while True:
+            event = self.vm_a.event_wait('MIGRATION')
+            if event['data']['status'] == 'completed':
+                break
+
+        if not online:
+            self.vm_a.shutdown()
+            self.vm_b.launch()
+            # TODO enable bitmap capability for vm_b in this case
+
+        self.vm_b.event_wait("RESUME", timeout=10.0)
+
+        self.check_bitmap(self.vm_b, sha256 if should_migrate else False)
+
+        if should_migrate:
+            self.vm_b.shutdown()
+            self.vm_b.launch()
+            self.check_bitmap(self.vm_b, sha256 if persistent else False)
+
+
+def inject_test_case(klass, name, method, *args, **kwargs):
+    mc = operator.methodcaller(method, *args, **kwargs)
+    setattr(klass, 'test_' + name, new.instancemethod(mc, None, klass))
+
+for cmb in list(itertools.product((True, False), repeat=3)):
+    name = ('_' if cmb[0] else '_not_') + 'persistent_'
+    name += ('_' if cmb[1] else '_not_') + 'migbitmap_'
+    name += '_online' if cmb[2] else '_offline'
+
+    # TODO fix shared-storage bitmap migration and enable cases for it
+    args = list(cmb) + [False]
+
+    inject_test_case(TestDirtyBitmapMigration, name, 'do_test_migration',
+                     *args)
+
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=['qcow2'])

tests/qemu-iotests/169.out

@@ -0,0 +1,5 @@
+........
+----------------------------------------------------------------------
+Ran 8 tests
+
+OK

tests/qemu-iotests/199

@@ -0,0 +1,118 @@
+#!/usr/bin/env python
+#
+# Tests for dirty bitmaps postcopy migration.
+#
+# Copyright (c) 2016-2017 Virtuozzo International GmbH. All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import os
+import iotests
+import time
+from iotests import qemu_img
+
+disk_a = os.path.join(iotests.test_dir, 'disk_a')
+disk_b = os.path.join(iotests.test_dir, 'disk_b')
+size = '256G'
+fifo = os.path.join(iotests.test_dir, 'mig_fifo')
+
+class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
+
+    def tearDown(self):
+        self.vm_a.shutdown()
+        self.vm_b.shutdown()
+        os.remove(disk_a)
+        os.remove(disk_b)
+        os.remove(fifo)
+
+    def setUp(self):
+        os.mkfifo(fifo)
+        qemu_img('create', '-f', iotests.imgfmt, disk_a, size)
+        qemu_img('create', '-f', iotests.imgfmt, disk_b, size)
+        self.vm_a = iotests.VM(path_suffix='a').add_drive(disk_a)
+        self.vm_b = iotests.VM(path_suffix='b').add_drive(disk_b)
+        self.vm_b.add_incoming("exec: cat '" + fifo + "'")
+        self.vm_a.launch()
+        self.vm_b.launch()
+
+    def test_postcopy(self):
+        write_size = 0x40000000
+        granularity = 512
+        chunk = 4096
+
+        result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
+                               name='bitmap', granularity=granularity)
+        self.assert_qmp(result, 'return', {});
+
+        s = 0
+        while s < write_size:
+            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+            s += 0x10000
+        s = 0x8000
+        while s < write_size:
+            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+            s += 0x10000
+
+        result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
+                               node='drive0', name='bitmap')
+        sha256 = result['return']['sha256']
+
+        result = self.vm_a.qmp('block-dirty-bitmap-clear', node='drive0',
+                               name='bitmap')
+        self.assert_qmp(result, 'return', {});
+        s = 0
+        while s < write_size:
+            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+            s += 0x10000
+
+        bitmaps_cap = {'capability': 'dirty-bitmaps', 'state': True}
+        events_cap = {'capability': 'events', 'state': True}
+
+        result = self.vm_a.qmp('migrate-set-capabilities',
+                               capabilities=[bitmaps_cap, events_cap])
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm_b.qmp('migrate-set-capabilities',
+                               capabilities=[bitmaps_cap])
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm_a.qmp('migrate', uri='exec:cat>' + fifo)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm_a.qmp('migrate-start-postcopy')
+        self.assert_qmp(result, 'return', {})
+
+        while True:
+            event = self.vm_a.event_wait('MIGRATION')
+            if event['data']['status'] == 'completed':
+                break
+
+        s = 0x8000
+        while s < write_size:
+            self.vm_b.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+            s += 0x10000
+
+        result = self.vm_b.qmp('query-block');
+        while len(result['return'][0]['dirty-bitmaps']) > 1:
+            time.sleep(2)
+            result = self.vm_b.qmp('query-block');
+
+        result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
+                               node='drive0', name='bitmap')
+
+        self.assert_qmp(result, 'return/sha256', sha256);
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=['qcow2'], supported_cache_modes=['none'])

tests/qemu-iotests/199.out

@@ -0,0 +1,5 @@
+.
+----------------------------------------------------------------------
+Ran 1 tests
+
+OK

tests/qemu-iotests/group

@@ -169,6 +169,7 @@
 162 auto quick
 163 rw auto quick
 165 rw auto quick
+169 rw auto quick
 170 rw auto quick
 171 rw auto quick
 172 auto
@@ -196,6 +197,7 @@
 196 rw auto quick
 197 rw auto quick
 198 rw auto
+199 rw auto
 200 rw auto
 201 rw auto migration
 202 rw auto quick

tests/qemu-iotests/iotests.py

@@ -537,6 +537,10 @@ def verify_platform(supported_oses=['linux']):
     if True not in [sys.platform.startswith(x) for x in supported_oses]:
         notrun('not suitable for this OS: %s' % sys.platform)
 
+def verify_cache_mode(supported_cache_modes=[]):
+    if supported_cache_modes and (cachemode not in supported_cache_modes):
+        notrun('not suitable for this cache mode: %s' % cachemode)
+
 def supports_quorum():
     return 'quorum' in qemu_img_pipe('--help')
 
@@ -545,7 +549,7 @@ def verify_quorum():
     if not supports_quorum():
         notrun('quorum support missing')
 
-def main(supported_fmts=[], supported_oses=['linux']):
+def main(supported_fmts=[], supported_oses=['linux'], supported_cache_modes=[]):
     '''Run tests'''
 
     global debug
@@ -562,6 +566,7 @@ def main(supported_fmts=[], supported_oses=['linux']):
     verbosity = 1
     verify_image_format(supported_fmts)
     verify_platform(supported_oses)
+    verify_cache_mode(supported_cache_modes)
 
     # We need to filter out the time taken from the output so that qemu-iotest
     # can reliably diff the results against master output.

vl.c

@@ -4503,6 +4503,7 @@ int main(int argc, char **argv, char **envp)
 
     blk_mig_init();
     ram_mig_init();
+    dirty_bitmap_mig_init();
 
     /* If the currently selected machine wishes to override the units-per-bus
      * property of its default HBA interface type, do so now. */