Archipelago » qemu

/*

 * 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 "block-migration.h"

#include <assert.h>

#include <pthread.h>

#define SECTOR_BITS 9

#define SECTOR_SIZE (1 << SECTOR_BITS)

#define SECTOR_MASK ~(SECTOR_SIZE - 1);

#define BLOCK_SIZE (block_mig_state->sectors_per_block << SECTOR_BITS) 

#define BLK_MIG_FLAG_DEVICE_BLOCK       0x01

#define BLK_MIG_FLAG_EOS                0x02

#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 BlkMigBlock {

    uint8_t *buf;

    BlkMigDevState *bmds;

    int64_t sector;

    struct iovec iov;

    QEMUIOVector qiov;

    BlockDriverAIOCB *aiocb;

    int ret;

    struct BlkMigBlock *next;

} BlkMigBlock;

typedef struct BlkMigState {

    int bulk_completed;

    int blk_enable;

    int shared_base;

    int no_dirty;

    QEMUFile *load_file;

    BlkMigDevState *bmds_first;

    int sectors_per_block;

    BlkMigBlock *first_blk;

    BlkMigBlock *last_blk;

    int submitted;

    int read_done;

    int transferred;

    int64_t print_completion;

} BlkMigState;

static BlkMigState *block_mig_state = NULL;  

static void blk_mig_read_cb(void *opaque, int ret)

{

    BlkMigBlock *blk = opaque;

    blk->ret = ret;

    /* insert at the end */

    if(block_mig_state->last_blk == NULL) {

        block_mig_state->first_blk = blk;

        block_mig_state->last_blk = blk;

    } else {

        block_mig_state->last_blk->next = blk;

        block_mig_state->last_blk = blk;

    }

    block_mig_state->submitted--;

    block_mig_state->read_done++;

    assert(block_mig_state->submitted >= 0);

    return;

}

static int mig_read_device_bulk(QEMUFile *f, BlkMigDevState *bms)

{ 

    int nr_sectors;

    int64_t total_sectors, cur_sector = 0;

    BlockDriverState *bs = bms->bs;

    BlkMigBlock *blk;

    blk = qemu_malloc(sizeof(BlkMigBlock));

    blk->buf = qemu_malloc(BLOCK_SIZE);

    cur_sector = bms->cur_sector;

    total_sectors = bdrv_getlength(bs) >> SECTOR_BITS;

    if(bms->shared_base) {

        while(cur_sector < bms->total_sectors && 

              !bdrv_is_allocated(bms->bs, cur_sector, 

                                 MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {

            cur_sector += nr_sectors;

        }

    }

    if(cur_sector >= total_sectors) {

        bms->cur_sector = total_sectors;

        qemu_free(blk->buf);

        qemu_free(blk);

        return 1;

    }

    if(cur_sector >= block_mig_state->print_completion) {

        printf("Completed %" PRId64 " %%\r", cur_sector * 100 / total_sectors);

        fflush(stdout);

        block_mig_state->print_completion += 

            (block_mig_state->sectors_per_block * 10000);

    }

    /* we going to transfder BLOCK_SIZE any way even if it is not allocated */

    nr_sectors = block_mig_state->sectors_per_block;

    cur_sector &= ~((int64_t)block_mig_state->sectors_per_block -1);

    if(total_sectors - cur_sector < block_mig_state->sectors_per_block) {

        nr_sectors = (total_sectors - cur_sector);

    }

    bms->cur_sector = cur_sector + nr_sectors;

    blk->sector = cur_sector;

    blk->bmds = bms;

    blk->next = NULL;

    blk->iov.iov_base = blk->buf;

    blk->iov.iov_len = nr_sectors * 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) {

        printf("Error reading sector %" PRId64 "\n", cur_sector);

        qemu_free(blk->buf);

        qemu_free(blk);

        return 0;

    }

    bdrv_reset_dirty(bms->bs, cur_sector, nr_sectors);

    block_mig_state->submitted++;

    return (bms->cur_sector >= total_sectors);

}

static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)

{ 

    int len, nr_sectors;

    int64_t total_sectors = bmds->total_sectors, cur_sector = 0;

    uint8_t *tmp_buf = NULL;

    BlockDriverState *bs = bmds->bs;

    tmp_buf = qemu_malloc(BLOCK_SIZE);

    cur_sector = bmds->cur_sector;

    if(bmds->shared_base) {

        while(cur_sector < bmds->total_sectors && 

              !bdrv_is_allocated(bmds->bs, cur_sector, 

                                 MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {

            cur_sector += nr_sectors;

        }

    }

    if(cur_sector >= total_sectors) {

        bmds->cur_sector = total_sectors;

        qemu_free(tmp_buf);

        return 1;

    }

    if(cur_sector >= block_mig_state->print_completion) {

        printf("Completed %" PRId64 " %%\r", cur_sector * 100 / total_sectors);

        fflush(stdout);

        block_mig_state->print_completion += 

            (block_mig_state->sectors_per_block * 10000);

    }

    cur_sector &= ~((int64_t)block_mig_state->sectors_per_block -1);

    /* we going to transfer 

       BLOCK_SIZE 

       any way even if it is not allocated */

    nr_sectors = block_mig_state->sectors_per_block;

    if(total_sectors - cur_sector < block_mig_state->sectors_per_block) {

        nr_sectors = (total_sectors - cur_sector);

    }

    if(bdrv_read(bs, cur_sector, tmp_buf, nr_sectors) < 0) {

        printf("Error reading sector %" PRId64 "\n", cur_sector);

    }

    bdrv_reset_dirty(bs, cur_sector, nr_sectors);

    /* Device name */

    qemu_put_be64(f,(cur_sector << SECTOR_BITS) | BLK_MIG_FLAG_DEVICE_BLOCK);

    len = strlen(bs->device_name);

    qemu_put_byte(f, len);

    qemu_put_buffer(f, (uint8_t *)bs->device_name, len);

    qemu_put_buffer(f, tmp_buf, 

                    BLOCK_SIZE);

    bmds->cur_sector = cur_sector + block_mig_state->sectors_per_block;

    qemu_free(tmp_buf);

    return (bmds->cur_sector >= total_sectors);

}

static void send_blk(QEMUFile *f, BlkMigBlock * blk)

{

    int len;

    /* Device name */ 

    qemu_put_be64(f,(blk->sector << SECTOR_BITS) | BLK_MIG_FLAG_DEVICE_BLOCK);

    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);

    return;

}

static void blk_mig_save_dev_info(QEMUFile *f, BlkMigDevState *bmds)

{

}

static void set_dirty_tracking(int enable)

{

    BlkMigDevState *bmds;

    for(bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {

        bdrv_set_dirty_tracking(bmds->bs,enable);

    }

    return;

}

static void init_blk_migration(QEMUFile *f)

{

    BlkMigDevState **pbmds, *bmds;

    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {

        if(bs->type == BDRV_TYPE_HD) {

            bmds = qemu_mallocz(sizeof(BlkMigDevState));

            bmds->bs = bs;

            bmds->bulk_completed = 0;

            bmds->total_sectors = bdrv_getlength(bs) >> SECTOR_BITS;

            bmds->shared_base = block_mig_state->shared_base;

            if(bmds->shared_base) {

                printf("Start migration for %s with shared base image\n", 

                       bs->device_name);

            } else {

                printf("Start full migration for %s\n", bs->device_name);

            }

            /* insert at the end */

            pbmds = &block_mig_state->bmds_first;

            while (*pbmds != NULL)

                pbmds = &(*pbmds)->next;

            *pbmds = bmds;

            blk_mig_save_dev_info(f, bmds);

        }

    } 

    block_mig_state->sectors_per_block = bdrv_get_sectors_per_chunk();

    return;

}

static int blk_mig_save_bulked_block(QEMUFile *f, int is_async)

{

    BlkMigDevState *bmds;

    for (bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {

        if(bmds->bulk_completed == 0) {

            if(is_async) {

                if(mig_read_device_bulk(f, bmds) == 1) {

                    /* completed bulk section for this device */

                    bmds->bulk_completed = 1;

                }

            } else {

                if(mig_save_device_bulk(f,bmds) == 1) {

                    /* completed bulk section for this device */

                    bmds->bulk_completed = 1;

                }

            }

            return 1;

        }

    }

    /* we reached here means bulk is completed */

    block_mig_state->bulk_completed = 1;

    return 0;

}

#define MAX_NUM_BLOCKS 4

static void blk_mig_save_dirty_blocks(QEMUFile *f)

{

    BlkMigDevState *bmds;

    uint8_t buf[BLOCK_SIZE];

    int64_t sector;

    int len;

    for(bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {

        for(sector = 0; sector < bmds->cur_sector;) {

            if(bdrv_get_dirty(bmds->bs,sector)) {

                if(bdrv_read(bmds->bs, sector, buf, 

                             block_mig_state->sectors_per_block) < 0) {

                }

                /* device name */

                qemu_put_be64(f,(sector << SECTOR_BITS) 

                              | BLK_MIG_FLAG_DEVICE_BLOCK);

                len = strlen(bmds->bs->device_name);

                qemu_put_byte(f, len);

                qemu_put_buffer(f, (uint8_t *)bmds->bs->device_name, len);

                qemu_put_buffer(f, buf, 

                                (block_mig_state->sectors_per_block * 

                                 SECTOR_SIZE));

                bdrv_reset_dirty(bmds->bs, sector, 

                                 block_mig_state->sectors_per_block);

                sector += block_mig_state->sectors_per_block;

            } else {

                /* sector is clean */

                sector += block_mig_state->sectors_per_block;

            }  

        }

    }

    return;

}

static void flush_blks(QEMUFile* f)

{

    BlkMigBlock *blk, *tmp;

    dprintf("%s Enter submitted %d read_done %d transfered\n", __FUNCTION__, 

            submitted, read_done, transfered);

    for(blk = block_mig_state->first_blk; 

        blk != NULL && !qemu_file_rate_limit(f); blk = tmp) {

        send_blk(f, blk);

        tmp = blk->next;

        qemu_free(blk->buf);

        qemu_free(blk);

        block_mig_state->read_done--;

        block_mig_state->transferred++;

        assert(block_mig_state->read_done >= 0);

    }

    block_mig_state->first_blk = blk;

    if(block_mig_state->first_blk == NULL) {

        block_mig_state->last_blk = NULL;

    }

    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);

    return;

}

static int is_stage2_completed(void)

{

    BlkMigDevState *bmds;

    if(block_mig_state->submitted > 0) {

        return 0;

    }

    for (bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {

        if(bmds->bulk_completed == 0) {

            return 0;

        }

    }

    return 1;

}

static int block_save_live(QEMUFile *f, int stage, void *opaque)

{

    int ret = 1;

    dprintf("Enter save live stage %d submitted %d transferred %d\n", stage, 

            submitted, transferred);

    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(f);

        /* start track dirty blocks */

        set_dirty_tracking(1);

    }

    flush_blks(f);

    /* control the rate of transfer */

    while ((block_mig_state->submitted + block_mig_state->read_done) * 

           (BLOCK_SIZE) < 

           (qemu_file_get_rate_limit(f))) {

        ret = blk_mig_save_bulked_block(f, 1);

        if (ret == 0) /* no more bulk blocks for now*/

            break;

    }

    flush_blks(f);

    if(stage == 3) {

        while(blk_mig_save_bulked_block(f, 0) != 0);

        blk_mig_save_dirty_blocks(f);

        /* stop track dirty blocks */

        set_dirty_tracking(0);;

        printf("\nBlock 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)

{

    int len, flags;

    char device_name[256];

    int64_t addr;

    BlockDriverState *bs;

    uint8_t *buf;

    block_mig_state->sectors_per_block = bdrv_get_sectors_per_chunk();

    buf = qemu_malloc(BLOCK_SIZE);

    do {

        addr = qemu_get_be64(f);

        flags = addr & ~SECTOR_MASK;

        addr &= SECTOR_MASK;

        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);

            qemu_get_buffer(f, buf, 

                            BLOCK_SIZE);

            if(bs != NULL) {

                bdrv_write(bs, (addr >> SECTOR_BITS), 

                           buf, block_mig_state->sectors_per_block);

            } else {

                printf("Error unknown block device %s\n", device_name);

            }

        } else if(flags & BLK_MIG_FLAG_EOS) {

        } else {

            printf("Unknown flags\n");

        }

    } while(!(flags & BLK_MIG_FLAG_EOS));

    qemu_free(buf);

    return 0;

}

static void block_set_params(int blk_enable, int shared_base, void *opaque)

{

    assert(opaque == block_mig_state);

    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;

    return;

}

void blk_mig_info(void)

{

    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {

        printf("Device %s\n", bs->device_name);

        if(bs->type == BDRV_TYPE_HD) {

            printf("device %s format %s\n", 

                   bs->device_name, bs->drv->format_name);

        }

    }

}

void blk_mig_init(void)

{ 

    block_mig_state = qemu_mallocz(sizeof(BlkMigState));

    register_savevm_live("block", 0, 1, block_set_params, block_save_live, 

                         NULL, block_load, block_mig_state);

}