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qemu/block-migration.c

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/*
* 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.
*
*/
#include "qemu-common.h"
#include "block_int.h"
#include "hw/hw.h"
#include "qemu-queue.h"
#include "monitor.h"
#include "block-migration.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 MAX_BLOCKS_READ 10000
#define BLOCKS_READ_CHANGE 100
#define INITIAL_BLOCKS_READ 100
//#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 completed_sectors;
int64_t total_sectors;
int64_t dirty;
QSIMPLEQ_ENTRY(BlkMigDevState) entry;
} BlkMigDevState;
typedef struct BlkMigBlock {
uint8_t *buf;
BlkMigDevState *bmds;
int64_t sector;
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;
} 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 void blk_mig_read_cb(void *opaque, int ret)
{
BlkMigBlock *blk = opaque;
blk->ret = ret;
QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
block_mig_state.submitted--;
block_mig_state.read_done++;
assert(block_mig_state.submitted >= 0);
}
static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
BlkMigDevState *bmds, int is_async)
{
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 = qemu_malloc(sizeof(BlkMigBlock));
blk->buf = qemu_malloc(BLOCK_SIZE);
blk->bmds = bmds;
blk->sector = cur_sector;
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);
blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
nr_sectors, blk_mig_read_cb, blk);
if (!blk->aiocb) {
goto error;
}
block_mig_state.submitted++;
} else {
if (bdrv_read(bs, cur_sector, blk->buf, nr_sectors) < 0) {
goto error;
}
blk_send(f, blk);
qemu_free(blk->buf);
qemu_free(blk);
}
bdrv_reset_dirty(bs, cur_sector, nr_sectors);
bmds->cur_sector = cur_sector + nr_sectors;
return (bmds->cur_sector >= total_sectors);
error:
monitor_printf(mon, "Error reading sector %" PRId64 "\n", cur_sector);
qemu_file_set_error(f);
qemu_free(blk->buf);
qemu_free(blk);
return 0;
}
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(Monitor *mon, QEMUFile *f)
{
BlkMigDevState *bmds;
BlockDriverState *bs;
int64_t sectors;
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;
for (bs = bdrv_first; bs != NULL; bs = bs->next) {
if (bs->type == BDRV_TYPE_HD) {
sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
if (sectors == 0) {
continue;
}
bmds = qemu_mallocz(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;
block_mig_state.total_sector_sum += sectors;
if (bmds->shared_base) {
monitor_printf(mon, "Start migration for %s with shared base "
"image\n",
bs->device_name);
} else {
monitor_printf(mon, "Start full migration for %s\n",
bs->device_name);
}
QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
}
}
}
static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f, int is_async)
{
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(mon, f, bmds, is_async) == 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;
}
}
progress = completed_sector_sum * 100 / block_mig_state.total_sector_sum;
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);
monitor_printf(mon, "Completed %d %%\r", progress);
monitor_flush(mon);
}
return ret;
}
#define MAX_NUM_BLOCKS 4
static void blk_mig_save_dirty_blocks(Monitor *mon, QEMUFile *f)
{
BlkMigDevState *bmds;
BlkMigBlock blk;
int64_t sector;
blk.buf = qemu_malloc(BLOCK_SIZE);
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
for (sector = 0; sector < bmds->cur_sector;) {
if (bdrv_get_dirty(bmds->bs, sector)) {
if (bdrv_read(bmds->bs, sector, blk.buf,
BDRV_SECTORS_PER_DIRTY_CHUNK) < 0) {
monitor_printf(mon, "Error reading sector %" PRId64 "\n",
sector);
qemu_file_set_error(f);
qemu_free(blk.buf);
return;
}
blk.bmds = bmds;
blk.sector = sector;
blk_send(f, &blk);
bdrv_reset_dirty(bmds->bs, sector,
BDRV_SECTORS_PER_DIRTY_CHUNK);
}
sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
}
}
qemu_free(blk.buf);
}
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);
break;
}
blk_send(f, blk);
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
qemu_free(blk->buf);
qemu_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 int is_stage2_completed(void)
{
BlkMigDevState *bmds;
if (block_mig_state.submitted > 0) {
return 0;
}
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
if (bmds->bulk_completed == 0) {
return 0;
}
}
return 1;
}
static void blk_mig_cleanup(Monitor *mon)
{
BlkMigDevState *bmds;
BlkMigBlock *blk;
while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
qemu_free(bmds);
}
while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
qemu_free(blk->buf);
qemu_free(blk);
}
set_dirty_tracking(0);
monitor_printf(mon, "\n");
}
static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
{
dprintf("Enter save live stage %d submitted %d transferred %d\n",
stage, block_mig_state.submitted, block_mig_state.transferred);
if (stage < 0) {
blk_mig_cleanup(mon);
return 0;
}
if (block_mig_state.blk_enable != 1) {
/* no need to migrate storage */
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
return 1;
}
if (stage == 1) {
init_blk_migration(mon, f);
/* start track dirty blocks */
set_dirty_tracking(1);
}
flush_blks(f);
if (qemu_file_has_error(f)) {
blk_mig_cleanup(mon);
return 0;
}
/* control the rate of transfer */
while ((block_mig_state.submitted +
block_mig_state.read_done) * BLOCK_SIZE <
qemu_file_get_rate_limit(f)) {
if (blk_mig_save_bulked_block(mon, f, 1) == 0) {
/* no more bulk blocks for now */
break;
}
}
flush_blks(f);
if (qemu_file_has_error(f)) {
blk_mig_cleanup(mon);
return 0;
}
if (stage == 3) {
while (blk_mig_save_bulked_block(mon, f, 0) != 0) {
/* empty */
}
blk_mig_save_dirty_blocks(mon, f);
blk_mig_cleanup(mon);
/* report completion */
qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
if (qemu_file_has_error(f)) {
return 0;
}
monitor_printf(mon, "Block migration completed\n");
}
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
return ((stage == 2) && is_stage2_completed());
}
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;
uint8_t *buf;
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;
}
buf = qemu_malloc(BLOCK_SIZE);
qemu_get_buffer(f, buf, BLOCK_SIZE);
bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);
qemu_free(buf);
} 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;
}
if (qemu_file_has_error(f)) {
return -EIO;
}
} while (!(flags & BLK_MIG_FLAG_EOS));
return 0;
}
static void block_set_params(int blk_enable, int shared_base, void *opaque)
{
block_mig_state.blk_enable = blk_enable;
block_mig_state.shared_base = shared_base;
/* shared base means that blk_enable = 1 */
block_mig_state.blk_enable |= shared_base;
}
void blk_mig_init(void)
{
QSIMPLEQ_INIT(&block_mig_state.bmds_list);
QSIMPLEQ_INIT(&block_mig_state.blk_list);
register_savevm_live("block", 0, 1, block_set_params, block_save_live,
NULL, block_load, &block_mig_state);
}
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