[14/17] qmp: add x-debug-block-dirty-bitmap-sha256

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 32aa6eb..5bec99b 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -558,3 +558,8 @@  BdrvDirtyBitmap *bdrv_next_dirty_bitmap(BlockDriverState *bs,
 
     return QLIST_NEXT(bitmap, list);
 }
+
+char *bdrv_dirty_bitmap_sha256(const BdrvDirtyBitmap *bitmap, Error **errp)
+{
+    return hbitmap_sha256(bitmap->bitmap, errp);
+}
diff --git a/blockdev.c b/blockdev.c
index 102ca9f..8b267d1 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2782,6 +2782,39 @@  void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
     aio_context_release(aio_context);
 }
 
+/**
+ * Completely clear a bitmap, for the purposes of synchronizing a bitmap
+ * immediately after a full backup operation.
+ */
+BlockDirtyBitmapSha256 *qmp_x_debug_block_dirty_bitmap_sha256(const char *node,
+                                                              const char *name,
+                                                              Error **errp)
+{
+    AioContext *aio_context;
+    BdrvDirtyBitmap *bitmap;
+    BlockDriverState *bs;
+    BlockDirtyBitmapSha256 *ret = NULL;
+    char *sha256;
+
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, &aio_context, errp);
+    if (!bitmap || !bs) {
+        return NULL;
+    }
+
+    sha256 = bdrv_dirty_bitmap_sha256(bitmap, errp);
+    if (sha256 == NULL) {
+        goto out;
+    }
+
+    ret = g_new(BlockDirtyBitmapSha256, 1);
+    ret->sha256 = sha256;
+
+out:
+    aio_context_release(aio_context);
+
+    return ret;
+}
+
 void hmp_drive_del(Monitor *mon, const QDict *qdict)
 {
     const char *id = qdict_get_str(qdict, "id");
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 20b3ec7..ded872a 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -78,4 +78,6 @@  void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap *bitmap);
 BdrvDirtyBitmap *bdrv_next_dirty_bitmap(BlockDriverState *bs,
                                         BdrvDirtyBitmap *bitmap);
 
+char *bdrv_dirty_bitmap_sha256(const BdrvDirtyBitmap *bitmap, Error **errp);
+
 #endif
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index eb46475..82f34a8 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -225,6 +225,14 @@  void hbitmap_deserialize_zeroes(HBitmap *hb, uint64_t start, uint64_t count,
 void hbitmap_deserialize_finish(HBitmap *hb);
 
 /**
+ * hbitmap_sha256:
+ * @bitmap: HBitmap to operate on.
+ *
+ * Returns SHA256 hash of the last level.
+ */
+char *hbitmap_sha256(const HBitmap *bitmap, Error **errp);
+
+/**
  * hbitmap_free:
  * @hb: HBitmap to operate on.
  *
diff --git a/qapi/block-core.json b/qapi/block-core.json
index bcd3b9e..9d57b1e 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1280,6 +1280,32 @@ 
   'data': 'BlockDirtyBitmap' }
 
 ##
+# @BlockDirtyBitmapSha256:
+#
+# SHA256 hash of dirty bitmap data
+#
+# @sha256: bitmap SHA256 hash
+#
+# Since: 2.8
+##
+  { 'struct': 'BlockDirtyBitmapSha256',
+    'data': {'sha256': 'str'} }
+
+##
+# @x-debug-block-dirty-bitmap-sha256
+#
+# Get bitmap SHA256
+#
+# Returns: BlockDirtyBitmapSha256 on success
+#          If @node is not a valid block device, DeviceNotFound
+#          If @name is not found, GenericError with an explanation
+#
+# Since 2.8
+##
+  { 'command': 'x-debug-block-dirty-bitmap-sha256',
+    'data': 'BlockDirtyBitmap', 'returns': 'BlockDirtyBitmapSha256' }
+
+##
 # @blockdev-mirror
 #
 # Start mirroring a block device's writes to a new destination.
diff --git a/util/hbitmap.c b/util/hbitmap.c
index 5d1a21c..b36afca 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -13,6 +13,7 @@ 
 #include "qemu/hbitmap.h"
 #include "qemu/host-utils.h"
 #include "trace.h"
+#include "crypto/hash.h"
 
 /* HBitmaps provides an array of bits.  The bits are stored as usual in an
  * array of unsigned longs, but HBitmap is also optimized to provide fast
@@ -669,3 +670,13 @@  void hbitmap_free_meta(HBitmap *hb)
     hbitmap_free(hb->meta);
     hb->meta = NULL;
 }
+
+char *hbitmap_sha256(const HBitmap *bitmap, Error **errp)
+{
+    size_t size = bitmap->sizes[HBITMAP_LEVELS - 1] * sizeof(unsigned long);
+    char *data = (char *)bitmap->levels[HBITMAP_LEVELS - 1];
+    char *hash = NULL;
+    qcrypto_hash_digest(QCRYPTO_HASH_ALG_SHA256, data, size, &hash, errp);
+
+    return hash;
+}