Imported Upstream version 1.1.50-2012.08upstream/1.1.50-2012.08

1 files changed, 768 insertions, 0 deletions

diff --git a/block-migration.c b/block-migration.c
new file mode 100644
index 0000000..7def8ab
--- /dev/null
+++ b/block-migration.c
@@ -0,0 +1,768 @@
+/*
+ * QEMU live block migration
+ *
+ * Copyright IBM, Corp. 2009
+ *
+ * Authors:
+ *  Liran Schour   <lirans@il.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+
+#include "qemu-common.h"
+#include "block_int.h"
+#include "hw/hw.h"
+#include "qemu-queue.h"
+#include "qemu-timer.h"
+#include "block-migration.h"
+#include "migration.h"
+#include "blockdev.h"
+#include <assert.h>
+
+#define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
+
+#define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
+#define BLK_MIG_FLAG_EOS                0x02
+#define BLK_MIG_FLAG_PROGRESS           0x04
+
+#define MAX_IS_ALLOCATED_SEARCH 65536
+
+//#define DEBUG_BLK_MIGRATION
+
+#ifdef DEBUG_BLK_MIGRATION
+#define DPRINTF(fmt, ...) \
+    do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+typedef struct BlkMigDevState {
+    BlockDriverState *bs;
+    int bulk_completed;
+    int shared_base;
+    int64_t cur_sector;
+    int64_t cur_dirty;
+    int64_t completed_sectors;
+    int64_t total_sectors;
+    int64_t dirty;
+    QSIMPLEQ_ENTRY(BlkMigDevState) entry;
+    unsigned long *aio_bitmap;
+} BlkMigDevState;
+
+typedef struct BlkMigBlock {
+    uint8_t *buf;
+    BlkMigDevState *bmds;
+    int64_t sector;
+    int nr_sectors;
+    struct iovec iov;
+    QEMUIOVector qiov;
+    BlockDriverAIOCB *aiocb;
+    int ret;
+    QSIMPLEQ_ENTRY(BlkMigBlock) entry;
+} BlkMigBlock;
+
+typedef struct BlkMigState {
+    int blk_enable;
+    int shared_base;
+    QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
+    QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
+    int submitted;
+    int read_done;
+    int transferred;
+    int64_t total_sector_sum;
+    int prev_progress;
+    int bulk_completed;
+    long double total_time;
+    long double prev_time_offset;
+    int reads;
+} BlkMigState;
+
+static BlkMigState block_mig_state;
+
+static void blk_send(QEMUFile *f, BlkMigBlock * blk)
+{
+    int len;
+
+    /* sector number and flags */
+    qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
+                     | BLK_MIG_FLAG_DEVICE_BLOCK);
+
+    /* device name */
+    len = strlen(blk->bmds->bs->device_name);
+    qemu_put_byte(f, len);
+    qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
+
+    qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
+}
+
+int blk_mig_active(void)
+{
+    return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
+}
+
+uint64_t blk_mig_bytes_transferred(void)
+{
+    BlkMigDevState *bmds;
+    uint64_t sum = 0;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        sum += bmds->completed_sectors;
+    }
+    return sum << BDRV_SECTOR_BITS;
+}
+
+uint64_t blk_mig_bytes_remaining(void)
+{
+    return blk_mig_bytes_total() - blk_mig_bytes_transferred();
+}
+
+uint64_t blk_mig_bytes_total(void)
+{
+    BlkMigDevState *bmds;
+    uint64_t sum = 0;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        sum += bmds->total_sectors;
+    }
+    return sum << BDRV_SECTOR_BITS;
+}
+
+static inline long double compute_read_bwidth(void)
+{
+    assert(block_mig_state.total_time != 0);
+    return (block_mig_state.reads / block_mig_state.total_time) * BLOCK_SIZE;
+}
+
+static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
+{
+    int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
+
+    if ((sector << BDRV_SECTOR_BITS) < bdrv_getlength(bmds->bs)) {
+        return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
+            (1UL << (chunk % (sizeof(unsigned long) * 8))));
+    } else {
+        return 0;
+    }
+}
+
+static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
+                             int nb_sectors, int set)
+{
+    int64_t start, end;
+    unsigned long val, idx, bit;
+
+    start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
+    end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
+
+    for (; start <= end; start++) {
+        idx = start / (sizeof(unsigned long) * 8);
+        bit = start % (sizeof(unsigned long) * 8);
+        val = bmds->aio_bitmap[idx];
+        if (set) {
+            val |= 1UL << bit;
+        } else {
+            val &= ~(1UL << bit);
+        }
+        bmds->aio_bitmap[idx] = val;
+    }
+}
+
+static void alloc_aio_bitmap(BlkMigDevState *bmds)
+{
+    BlockDriverState *bs = bmds->bs;
+    int64_t bitmap_size;
+
+    bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
+            BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
+    bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
+
+    bmds->aio_bitmap = g_malloc0(bitmap_size);
+}
+
+static void blk_mig_read_cb(void *opaque, int ret)
+{
+    long double curr_time = qemu_get_clock_ns(rt_clock);
+    BlkMigBlock *blk = opaque;
+
+    blk->ret = ret;
+
+    block_mig_state.reads++;
+    block_mig_state.total_time += (curr_time - block_mig_state.prev_time_offset);
+    block_mig_state.prev_time_offset = curr_time;
+
+    QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
+    bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
+
+    block_mig_state.submitted--;
+    block_mig_state.read_done++;
+    assert(block_mig_state.submitted >= 0);
+}
+
+static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
+{
+    int64_t total_sectors = bmds->total_sectors;
+    int64_t cur_sector = bmds->cur_sector;
+    BlockDriverState *bs = bmds->bs;
+    BlkMigBlock *blk;
+    int nr_sectors;
+
+    if (bmds->shared_base) {
+        while (cur_sector < total_sectors &&
+               !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
+                                  &nr_sectors)) {
+            cur_sector += nr_sectors;
+        }
+    }
+
+    if (cur_sector >= total_sectors) {
+        bmds->cur_sector = bmds->completed_sectors = total_sectors;
+        return 1;
+    }
+
+    bmds->completed_sectors = cur_sector;
+
+    cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
+
+    /* we are going to transfer a full block even if it is not allocated */
+    nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
+
+    if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
+        nr_sectors = total_sectors - cur_sector;
+    }
+
+    blk = g_malloc(sizeof(BlkMigBlock));
+    blk->buf = g_malloc(BLOCK_SIZE);
+    blk->bmds = bmds;
+    blk->sector = cur_sector;
+    blk->nr_sectors = nr_sectors;
+
+    blk->iov.iov_base = blk->buf;
+    blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
+    qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
+
+    if (block_mig_state.submitted == 0) {
+        block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
+    }
+
+    blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
+                                nr_sectors, blk_mig_read_cb, blk);
+    block_mig_state.submitted++;
+
+    bdrv_reset_dirty(bs, cur_sector, nr_sectors);
+    bmds->cur_sector = cur_sector + nr_sectors;
+
+    return (bmds->cur_sector >= total_sectors);
+}
+
+static void set_dirty_tracking(int enable)
+{
+    BlkMigDevState *bmds;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        bdrv_set_dirty_tracking(bmds->bs, enable);
+    }
+}
+
+static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
+{
+    BlkMigDevState *bmds;
+    int64_t sectors;
+
+    if (!bdrv_is_read_only(bs)) {
+        sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+        if (sectors <= 0) {
+            return;
+        }
+
+        bmds = g_malloc0(sizeof(BlkMigDevState));
+        bmds->bs = bs;
+        bmds->bulk_completed = 0;
+        bmds->total_sectors = sectors;
+        bmds->completed_sectors = 0;
+        bmds->shared_base = block_mig_state.shared_base;
+        alloc_aio_bitmap(bmds);
+        drive_get_ref(drive_get_by_blockdev(bs));
+        bdrv_set_in_use(bs, 1);
+
+        block_mig_state.total_sector_sum += sectors;
+
+        if (bmds->shared_base) {
+            DPRINTF("Start migration for %s with shared base image\n",
+                    bs->device_name);
+        } else {
+            DPRINTF("Start full migration for %s\n", bs->device_name);
+        }
+
+        QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
+    }
+}
+
+static void init_blk_migration(QEMUFile *f)
+{
+    block_mig_state.submitted = 0;
+    block_mig_state.read_done = 0;
+    block_mig_state.transferred = 0;
+    block_mig_state.total_sector_sum = 0;
+    block_mig_state.prev_progress = -1;
+    block_mig_state.bulk_completed = 0;
+    block_mig_state.total_time = 0;
+    block_mig_state.reads = 0;
+
+    bdrv_iterate(init_blk_migration_it, NULL);
+}
+
+static int blk_mig_save_bulked_block(QEMUFile *f)
+{
+    int64_t completed_sector_sum = 0;
+    BlkMigDevState *bmds;
+    int progress;
+    int ret = 0;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        if (bmds->bulk_completed == 0) {
+            if (mig_save_device_bulk(f, bmds) == 1) {
+                /* completed bulk section for this device */
+                bmds->bulk_completed = 1;
+            }
+            completed_sector_sum += bmds->completed_sectors;
+            ret = 1;
+            break;
+        } else {
+            completed_sector_sum += bmds->completed_sectors;
+        }
+    }
+
+    if (block_mig_state.total_sector_sum != 0) {
+        progress = completed_sector_sum * 100 /
+                   block_mig_state.total_sector_sum;
+    } else {
+        progress = 100;
+    }
+    if (progress != block_mig_state.prev_progress) {
+        block_mig_state.prev_progress = progress;
+        qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
+                         | BLK_MIG_FLAG_PROGRESS);
+        DPRINTF("Completed %d %%\r", progress);
+    }
+
+    return ret;
+}
+
+static void blk_mig_reset_dirty_cursor(void)
+{
+    BlkMigDevState *bmds;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        bmds->cur_dirty = 0;
+    }
+}
+
+static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
+                                 int is_async)
+{
+    BlkMigBlock *blk;
+    int64_t total_sectors = bmds->total_sectors;
+    int64_t sector;
+    int nr_sectors;
+    int ret = -EIO;
+
+    for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
+        if (bmds_aio_inflight(bmds, sector)) {
+            bdrv_drain_all();
+        }
+        if (bdrv_get_dirty(bmds->bs, sector)) {
+
+            if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
+                nr_sectors = total_sectors - sector;
+            } else {
+                nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
+            }
+            blk = g_malloc(sizeof(BlkMigBlock));
+            blk->buf = g_malloc(BLOCK_SIZE);
+            blk->bmds = bmds;
+            blk->sector = sector;
+            blk->nr_sectors = nr_sectors;
+
+            if (is_async) {
+                blk->iov.iov_base = blk->buf;
+                blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
+                qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
+
+                if (block_mig_state.submitted == 0) {
+                    block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
+                }
+
+                blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
+                                            nr_sectors, blk_mig_read_cb, blk);
+                block_mig_state.submitted++;
+                bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
+            } else {
+                ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
+                if (ret < 0) {
+                    goto error;
+                }
+                blk_send(f, blk);
+
+                g_free(blk->buf);
+                g_free(blk);
+            }
+
+            bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
+            break;
+        }
+        sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
+        bmds->cur_dirty = sector;
+    }
+
+    return (bmds->cur_dirty >= bmds->total_sectors);
+
+error:
+    DPRINTF("Error reading sector %" PRId64 "\n", sector);
+    qemu_file_set_error(f, ret);
+    g_free(blk->buf);
+    g_free(blk);
+    return 0;
+}
+
+static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
+{
+    BlkMigDevState *bmds;
+    int ret = 0;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        if (mig_save_device_dirty(f, bmds, is_async) == 0) {
+            ret = 1;
+            break;
+        }
+    }
+
+    return ret;
+}
+
+static void flush_blks(QEMUFile* f)
+{
+    BlkMigBlock *blk;
+
+    DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
+            __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
+            block_mig_state.transferred);
+
+    while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
+        if (qemu_file_rate_limit(f)) {
+            break;
+        }
+        if (blk->ret < 0) {
+            qemu_file_set_error(f, blk->ret);
+            break;
+        }
+        blk_send(f, blk);
+
+        QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
+        g_free(blk->buf);
+        g_free(blk);
+
+        block_mig_state.read_done--;
+        block_mig_state.transferred++;
+        assert(block_mig_state.read_done >= 0);
+    }
+
+    DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
+            block_mig_state.submitted, block_mig_state.read_done,
+            block_mig_state.transferred);
+}
+
+static int64_t get_remaining_dirty(void)
+{
+    BlkMigDevState *bmds;
+    int64_t dirty = 0;
+
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        dirty += bdrv_get_dirty_count(bmds->bs);
+    }
+
+    return dirty * BLOCK_SIZE;
+}
+
+static int is_stage2_completed(void)
+{
+    int64_t remaining_dirty;
+    long double bwidth;
+
+    if (block_mig_state.bulk_completed == 1) {
+
+        remaining_dirty = get_remaining_dirty();
+        if (remaining_dirty == 0) {
+            return 1;
+        }
+
+        bwidth = compute_read_bwidth();
+
+        if ((remaining_dirty / bwidth) <=
+            migrate_max_downtime()) {
+            /* finish stage2 because we think that we can finish remaining work
+               below max_downtime */
+
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static void blk_mig_cleanup(void)
+{
+    BlkMigDevState *bmds;
+    BlkMigBlock *blk;
+
+    set_dirty_tracking(0);
+
+    while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
+        QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
+        bdrv_set_in_use(bmds->bs, 0);
+        drive_put_ref(drive_get_by_blockdev(bmds->bs));
+        g_free(bmds->aio_bitmap);
+        g_free(bmds);
+    }
+
+    while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
+        QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
+        g_free(blk->buf);
+        g_free(blk);
+    }
+}
+
+static void block_migration_cancel(void *opaque)
+{
+    blk_mig_cleanup();
+}
+
+static int block_save_setup(QEMUFile *f, void *opaque)
+{
+    int ret;
+
+    DPRINTF("Enter save live setup submitted %d transferred %d\n",
+            block_mig_state.submitted, block_mig_state.transferred);
+
+    init_blk_migration(f);
+
+    /* start track dirty blocks */
+    set_dirty_tracking(1);
+
+    flush_blks(f);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        blk_mig_cleanup();
+        return ret;
+    }
+
+    blk_mig_reset_dirty_cursor();
+
+    qemu_put_be64(f, BLK_MIG_FLAG_EOS);
+
+    return 0;
+}
+
+static int block_save_iterate(QEMUFile *f, void *opaque)
+{
+    int ret;
+
+    DPRINTF("Enter save live iterate submitted %d transferred %d\n",
+            block_mig_state.submitted, block_mig_state.transferred);
+
+    flush_blks(f);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        blk_mig_cleanup();
+        return ret;
+    }
+
+    blk_mig_reset_dirty_cursor();
+
+    /* control the rate of transfer */
+    while ((block_mig_state.submitted +
+            block_mig_state.read_done) * BLOCK_SIZE <
+           qemu_file_get_rate_limit(f)) {
+        if (block_mig_state.bulk_completed == 0) {
+            /* first finish the bulk phase */
+            if (blk_mig_save_bulked_block(f) == 0) {
+                /* finished saving bulk on all devices */
+                block_mig_state.bulk_completed = 1;
+            }
+        } else {
+            if (blk_mig_save_dirty_block(f, 1) == 0) {
+                /* no more dirty blocks */
+                break;
+            }
+        }
+    }
+
+    flush_blks(f);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        blk_mig_cleanup();
+        return ret;
+    }
+
+    qemu_put_be64(f, BLK_MIG_FLAG_EOS);
+
+    return is_stage2_completed();
+}
+
+static int block_save_complete(QEMUFile *f, void *opaque)
+{
+    int ret;
+
+    DPRINTF("Enter save live complete submitted %d transferred %d\n",
+            block_mig_state.submitted, block_mig_state.transferred);
+
+    flush_blks(f);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        blk_mig_cleanup();
+        return ret;
+    }
+
+    blk_mig_reset_dirty_cursor();
+
+    /* we know for sure that save bulk is completed and
+       all async read completed */
+    assert(block_mig_state.submitted == 0);
+
+    while (blk_mig_save_dirty_block(f, 0) != 0) {
+        /* Do nothing */
+    }
+    blk_mig_cleanup();
+
+    /* report completion */
+    qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    DPRINTF("Block migration completed\n");
+
+    qemu_put_be64(f, BLK_MIG_FLAG_EOS);
+
+    return 0;
+}
+
+static int block_load(QEMUFile *f, void *opaque, int version_id)
+{
+    static int banner_printed;
+    int len, flags;
+    char device_name[256];
+    int64_t addr;
+    BlockDriverState *bs, *bs_prev = NULL;
+    uint8_t *buf;
+    int64_t total_sectors = 0;
+    int nr_sectors;
+    int ret;
+
+    do {
+        addr = qemu_get_be64(f);
+
+        flags = addr & ~BDRV_SECTOR_MASK;
+        addr >>= BDRV_SECTOR_BITS;
+
+        if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
+            /* get device name */
+            len = qemu_get_byte(f);
+            qemu_get_buffer(f, (uint8_t *)device_name, len);
+            device_name[len] = '\0';
+
+            bs = bdrv_find(device_name);
+            if (!bs) {
+                fprintf(stderr, "Error unknown block device %s\n",
+                        device_name);
+                return -EINVAL;
+            }
+
+            if (bs != bs_prev) {
+                bs_prev = bs;
+                total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+                if (total_sectors <= 0) {
+                    error_report("Error getting length of block device %s",
+                                 device_name);
+                    return -EINVAL;
+                }
+            }
+
+            if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
+                nr_sectors = total_sectors - addr;
+            } else {
+                nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
+            }
+
+            buf = g_malloc(BLOCK_SIZE);
+
+            qemu_get_buffer(f, buf, BLOCK_SIZE);
+            ret = bdrv_write(bs, addr, buf, nr_sectors);
+
+            g_free(buf);
+            if (ret < 0) {
+                return ret;
+            }
+        } else if (flags & BLK_MIG_FLAG_PROGRESS) {
+            if (!banner_printed) {
+                printf("Receiving block device images\n");
+                banner_printed = 1;
+            }
+            printf("Completed %d %%%c", (int)addr,
+                   (addr == 100) ? '\n' : '\r');
+            fflush(stdout);
+        } else if (!(flags & BLK_MIG_FLAG_EOS)) {
+            fprintf(stderr, "Unknown flags\n");
+            return -EINVAL;
+        }
+        ret = qemu_file_get_error(f);
+        if (ret != 0) {
+            return ret;
+        }
+    } while (!(flags & BLK_MIG_FLAG_EOS));
+
+    return 0;
+}
+
+static void block_set_params(const MigrationParams *params, void *opaque)
+{
+    block_mig_state.blk_enable = params->blk;
+    block_mig_state.shared_base = params->shared;
+
+    /* shared base means that blk_enable = 1 */
+    block_mig_state.blk_enable |= params->shared;
+}
+
+static bool block_is_active(void *opaque)
+{
+    return block_mig_state.blk_enable == 1;
+}
+
+SaveVMHandlers savevm_block_handlers = {
+    .set_params = block_set_params,
+    .save_live_setup = block_save_setup,
+    .save_live_iterate = block_save_iterate,
+    .save_live_complete = block_save_complete,
+    .load_state = block_load,
+    .cancel = block_migration_cancel,
+    .is_active = block_is_active,
+};
+
+void blk_mig_init(void)
+{
+    QSIMPLEQ_INIT(&block_mig_state.bmds_list);
+    QSIMPLEQ_INIT(&block_mig_state.blk_list);
+
+    register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
+                         &block_mig_state);
+}