new file mode 100644
@@ -0,0 +1,195 @@
+/*
+ * QEMU I/O channels block driver
+ *
+ * Copyright (c) 2022 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "migration/channel-block.h"
+#include "qapi/error.h"
+#include "block/block.h"
+#include "trace.h"
+
+QIOChannelBlock *
+qio_channel_block_new(BlockDriverState *bs)
+{
+ QIOChannelBlock *ioc;
+
+ ioc = QIO_CHANNEL_BLOCK(object_new(TYPE_QIO_CHANNEL_BLOCK));
+
+ bdrv_ref(bs);
+ ioc->bs = bs;
+
+ return ioc;
+}
+
+
+static void
+qio_channel_block_finalize(Object *obj)
+{
+ QIOChannelBlock *ioc = QIO_CHANNEL_BLOCK(obj);
+
+ g_clear_pointer(&ioc->bs, bdrv_unref);
+}
+
+
+static ssize_t
+qio_channel_block_readv(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ int **fds,
+ size_t *nfds,
+ Error **errp)
+{
+ QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
+ QEMUIOVector qiov;
+ int ret;
+
+ qemu_iovec_init_external(&qiov, (struct iovec *)iov, niov);
+ ret = bdrv_readv_vmstate(bioc->bs, &qiov, bioc->offset);
+ if (ret < 0) {
+ return ret;
+ }
+
+ bioc->offset += qiov.size;
+ return qiov.size;
+}
+
+
+static ssize_t
+qio_channel_block_writev(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ int *fds,
+ size_t nfds,
+ int flags,
+ Error **errp)
+{
+ QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
+ QEMUIOVector qiov;
+ int ret;
+
+ qemu_iovec_init_external(&qiov, (struct iovec *)iov, niov);
+ ret = bdrv_writev_vmstate(bioc->bs, &qiov, bioc->offset);
+ if (ret < 0) {
+ return ret;
+ }
+
+ bioc->offset += qiov.size;
+ return qiov.size;
+}
+
+
+static int
+qio_channel_block_set_blocking(QIOChannel *ioc,
+ bool enabled,
+ Error **errp)
+{
+ if (!enabled) {
+ error_setg(errp, "Non-blocking mode not supported for block devices");
+ return -1;
+ }
+ return 0;
+}
+
+
+static off_t
+qio_channel_block_seek(QIOChannel *ioc,
+ off_t offset,
+ int whence,
+ Error **errp)
+{
+ QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
+
+ switch (whence) {
+ case SEEK_SET:
+ bioc->offset = offset;
+ break;
+ case SEEK_CUR:
+ bioc->offset += whence;
+ break;
+ case SEEK_END:
+ error_setg(errp, "Size of VMstate region is unknown");
+ return (off_t)-1;
+ default:
+ g_assert_not_reached();
+ }
+
+ return bioc->offset;
+}
+
+
+static int
+qio_channel_block_close(QIOChannel *ioc,
+ Error **errp)
+{
+ QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
+ int rv = bdrv_flush(bioc->bs);
+
+ if (rv < 0) {
+ error_setg_errno(errp, -rv,
+ "Unable to flush VMState");
+ return -1;
+ }
+
+ g_clear_pointer(&bioc->bs, bdrv_unref);
+ bioc->offset = 0;
+
+ return 0;
+}
+
+
+static void
+qio_channel_block_set_aio_fd_handler(QIOChannel *ioc,
+ AioContext *ctx,
+ IOHandler *io_read,
+ IOHandler *io_write,
+ void *opaque)
+{
+ /* XXX anything we can do here ? */
+}
+
+
+static void
+qio_channel_block_class_init(ObjectClass *klass,
+ void *class_data G_GNUC_UNUSED)
+{
+ QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
+
+ ioc_klass->io_writev = qio_channel_block_writev;
+ ioc_klass->io_readv = qio_channel_block_readv;
+ ioc_klass->io_set_blocking = qio_channel_block_set_blocking;
+ ioc_klass->io_seek = qio_channel_block_seek;
+ ioc_klass->io_close = qio_channel_block_close;
+ ioc_klass->io_set_aio_fd_handler = qio_channel_block_set_aio_fd_handler;
+}
+
+static const TypeInfo qio_channel_block_info = {
+ .parent = TYPE_QIO_CHANNEL,
+ .name = TYPE_QIO_CHANNEL_BLOCK,
+ .instance_size = sizeof(QIOChannelBlock),
+ .instance_finalize = qio_channel_block_finalize,
+ .class_init = qio_channel_block_class_init,
+};
+
+static void
+qio_channel_block_register_types(void)
+{
+ type_register_static(&qio_channel_block_info);
+}
+
+type_init(qio_channel_block_register_types);
new file mode 100644
@@ -0,0 +1,59 @@
+/*
+ * QEMU I/O channels block driver
+ *
+ * Copyright (c) 2022 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QIO_CHANNEL_BLOCK_H
+#define QIO_CHANNEL_BLOCK_H
+
+#include "io/channel.h"
+#include "qom/object.h"
+
+#define TYPE_QIO_CHANNEL_BLOCK "qio-channel-block"
+OBJECT_DECLARE_SIMPLE_TYPE(QIOChannelBlock, QIO_CHANNEL_BLOCK)
+
+
+/**
+ * QIOChannelBlock:
+ *
+ * The QIOChannelBlock object provides a channel implementation
+ * that is able to perform I/O on the BlockDriverState objects
+ * to the VMState region.
+ */
+
+struct QIOChannelBlock {
+ QIOChannel parent;
+ BlockDriverState *bs;
+ off_t offset;
+};
+
+
+/**
+ * qio_channel_block_new:
+ * @bs: the block driver state
+ *
+ * Create a new IO channel object that can perform
+ * I/O on a BlockDriverState object to the VMState
+ * region
+ *
+ * Returns: the new channel object
+ */
+QIOChannelBlock *
+qio_channel_block_new(BlockDriverState *bs);
+
+#endif /* QIO_CHANNEL_BLOCK_H */
@@ -13,6 +13,7 @@ softmmu_ss.add(migration_files)
softmmu_ss.add(files(
'block-dirty-bitmap.c',
'channel.c',
+ 'channel-block.c',
'colo-failover.c',
'colo.c',
'exec.c',