Archipelago » qemu

/*

 * QEMU System Emulator

 *

 * Copyright (c) 2003-2008 Fabrice Bellard

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include <stdint.h>

#include <stdarg.h>

#include <stdlib.h>

#ifndef _WIN32

#include <sys/types.h>

#include <sys/mman.h>

#endif

#include "config.h"

#include "monitor/monitor.h"

#include "sysemu/sysemu.h"

#include "qemu/bitops.h"

#include "qemu/bitmap.h"

#include "sysemu/arch_init.h"

#include "audio/audio.h"

#include "hw/i386/pc.h"

#include "hw/pci/pci.h"

#include "hw/audio/audio.h"

#include "sysemu/kvm.h"

#include "migration/migration.h"

#include "hw/i386/smbios.h"

#include "exec/address-spaces.h"

#include "hw/audio/pcspk.h"

#include "migration/page_cache.h"

#include "qemu/config-file.h"

#include "qmp-commands.h"

#include "trace.h"

#include "exec/cpu-all.h"

#include "hw/acpi/acpi.h"

#ifdef DEBUG_ARCH_INIT

#define DPRINTF(fmt, ...) \

    do { fprintf(stdout, "arch_init: " fmt, ## __VA_ARGS__); } while (0)

#else

#define DPRINTF(fmt, ...) \

    do { } while (0)

#endif

#ifdef TARGET_SPARC

int graphic_width = 1024;

int graphic_height = 768;

int graphic_depth = 8;

#else

int graphic_width = 800;

int graphic_height = 600;

int graphic_depth = 32;

#endif

#if defined(TARGET_ALPHA)

#define QEMU_ARCH QEMU_ARCH_ALPHA

#elif defined(TARGET_ARM)

#define QEMU_ARCH QEMU_ARCH_ARM

#elif defined(TARGET_CRIS)

#define QEMU_ARCH QEMU_ARCH_CRIS

#elif defined(TARGET_I386)

#define QEMU_ARCH QEMU_ARCH_I386

#elif defined(TARGET_M68K)

#define QEMU_ARCH QEMU_ARCH_M68K

#elif defined(TARGET_LM32)

#define QEMU_ARCH QEMU_ARCH_LM32

#elif defined(TARGET_MICROBLAZE)

#define QEMU_ARCH QEMU_ARCH_MICROBLAZE

#elif defined(TARGET_MIPS)

#define QEMU_ARCH QEMU_ARCH_MIPS

#elif defined(TARGET_MOXIE)

#define QEMU_ARCH QEMU_ARCH_MOXIE

#elif defined(TARGET_OPENRISC)

#define QEMU_ARCH QEMU_ARCH_OPENRISC

#elif defined(TARGET_PPC)

#define QEMU_ARCH QEMU_ARCH_PPC

#elif defined(TARGET_S390X)

#define QEMU_ARCH QEMU_ARCH_S390X

#elif defined(TARGET_SH4)

#define QEMU_ARCH QEMU_ARCH_SH4

#elif defined(TARGET_SPARC)

#define QEMU_ARCH QEMU_ARCH_SPARC

#elif defined(TARGET_XTENSA)

#define QEMU_ARCH QEMU_ARCH_XTENSA

#elif defined(TARGET_UNICORE32)

#define QEMU_ARCH QEMU_ARCH_UNICORE32

#endif

const uint32_t arch_type = QEMU_ARCH;

static bool mig_throttle_on;

static int dirty_rate_high_cnt;

static void check_guest_throttling(void);

/***********************************************************/

/* ram save/restore */

#define RAM_SAVE_FLAG_FULL     0x01 /* Obsolete, not used anymore */

#define RAM_SAVE_FLAG_COMPRESS 0x02

#define RAM_SAVE_FLAG_MEM_SIZE 0x04

#define RAM_SAVE_FLAG_PAGE     0x08

#define RAM_SAVE_FLAG_EOS      0x10

#define RAM_SAVE_FLAG_CONTINUE 0x20

#define RAM_SAVE_FLAG_XBZRLE   0x40

/* 0x80 is reserved in migration.h start with 0x100 next */

static struct defconfig_file {

    const char *filename;

    /* Indicates it is an user config file (disabled by -no-user-config) */

    bool userconfig;

} default_config_files[] = {

    { CONFIG_QEMU_CONFDIR "/qemu.conf",                   true },

    { CONFIG_QEMU_CONFDIR "/target-" TARGET_NAME ".conf", true },

    { NULL }, /* end of list */

};

int qemu_read_default_config_files(bool userconfig)

{

    int ret;

    struct defconfig_file *f;

    for (f = default_config_files; f->filename; f++) {

        if (!userconfig && f->userconfig) {

            continue;

        }

        ret = qemu_read_config_file(f->filename);

        if (ret < 0 && ret != -ENOENT) {

            return ret;

        }

    }

    return 0;

}

static inline bool is_zero_page(uint8_t *p)

{

    return buffer_find_nonzero_offset(p, TARGET_PAGE_SIZE) ==

        TARGET_PAGE_SIZE;

}

/* struct contains XBZRLE cache and a static page

   used by the compression */

static struct {

    /* buffer used for XBZRLE encoding */

    uint8_t *encoded_buf;

    /* buffer for storing page content */

    uint8_t *current_buf;

    /* buffer used for XBZRLE decoding */

    uint8_t *decoded_buf;

    /* Cache for XBZRLE */

    PageCache *cache;

} XBZRLE = {

    .encoded_buf = NULL,

    .current_buf = NULL,

    .decoded_buf = NULL,

    .cache = NULL,

};

int64_t xbzrle_cache_resize(int64_t new_size)

{

    if (XBZRLE.cache != NULL) {

        return cache_resize(XBZRLE.cache, new_size / TARGET_PAGE_SIZE) *

            TARGET_PAGE_SIZE;

    }

    return pow2floor(new_size);

}

/* accounting for migration statistics */

typedef struct AccountingInfo {

    uint64_t dup_pages;

    uint64_t skipped_pages;

    uint64_t norm_pages;

    uint64_t iterations;

    uint64_t xbzrle_bytes;

    uint64_t xbzrle_pages;

    uint64_t xbzrle_cache_miss;

    uint64_t xbzrle_overflows;

} AccountingInfo;

static AccountingInfo acct_info;

static void acct_clear(void)

{

    memset(&acct_info, 0, sizeof(acct_info));

}

uint64_t dup_mig_bytes_transferred(void)

{

    return acct_info.dup_pages * TARGET_PAGE_SIZE;

}

uint64_t dup_mig_pages_transferred(void)

{

    return acct_info.dup_pages;

}

uint64_t skipped_mig_bytes_transferred(void)

{

    return acct_info.skipped_pages * TARGET_PAGE_SIZE;

}

uint64_t skipped_mig_pages_transferred(void)

{

    return acct_info.skipped_pages;

}

uint64_t norm_mig_bytes_transferred(void)

{

    return acct_info.norm_pages * TARGET_PAGE_SIZE;

}

uint64_t norm_mig_pages_transferred(void)

{

    return acct_info.norm_pages;

}

uint64_t xbzrle_mig_bytes_transferred(void)

{

    return acct_info.xbzrle_bytes;

}

uint64_t xbzrle_mig_pages_transferred(void)

{

    return acct_info.xbzrle_pages;

}

uint64_t xbzrle_mig_pages_cache_miss(void)

{

    return acct_info.xbzrle_cache_miss;

}

uint64_t xbzrle_mig_pages_overflow(void)

{

    return acct_info.xbzrle_overflows;

}

static size_t save_block_hdr(QEMUFile *f, RAMBlock *block, ram_addr_t offset,

                             int cont, int flag)

{

    size_t size;

    qemu_put_be64(f, offset | cont | flag);

    size = 8;

    if (!cont) {

        qemu_put_byte(f, strlen(block->idstr));

        qemu_put_buffer(f, (uint8_t *)block->idstr,

                        strlen(block->idstr));

        size += 1 + strlen(block->idstr);

    }

    return size;

}

#define ENCODING_FLAG_XBZRLE 0x1

static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,

                            ram_addr_t current_addr, RAMBlock *block,

                            ram_addr_t offset, int cont, bool last_stage)

{

    int encoded_len = 0, bytes_sent = -1;

    uint8_t *prev_cached_page;

    if (!cache_is_cached(XBZRLE.cache, current_addr)) {

        if (!last_stage) {

            cache_insert(XBZRLE.cache, current_addr, current_data);

        }

        acct_info.xbzrle_cache_miss++;

        return -1;

    }

    prev_cached_page = get_cached_data(XBZRLE.cache, current_addr);

    /* save current buffer into memory */

    memcpy(XBZRLE.current_buf, current_data, TARGET_PAGE_SIZE);

    /* XBZRLE encoding (if there is no overflow) */

    encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf,

                                       TARGET_PAGE_SIZE, XBZRLE.encoded_buf,

                                       TARGET_PAGE_SIZE);

    if (encoded_len == 0) {

        DPRINTF("Skipping unmodified page\n");

        return 0;

    } else if (encoded_len == -1) {

        DPRINTF("Overflow\n");

        acct_info.xbzrle_overflows++;

        /* update data in the cache */

        memcpy(prev_cached_page, current_data, TARGET_PAGE_SIZE);

        return -1;

    }

    /* we need to update the data in the cache, in order to get the same data */

    if (!last_stage) {

        memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE);

    }

    /* Send XBZRLE based compressed page */

    bytes_sent = save_block_hdr(f, block, offset, cont, RAM_SAVE_FLAG_XBZRLE);

    qemu_put_byte(f, ENCODING_FLAG_XBZRLE);

    qemu_put_be16(f, encoded_len);

    qemu_put_buffer(f, XBZRLE.encoded_buf, encoded_len);

    bytes_sent += encoded_len + 1 + 2;

    acct_info.xbzrle_pages++;

    acct_info.xbzrle_bytes += bytes_sent;

    return bytes_sent;

}

/* This is the last block that we have visited serching for dirty pages

 */

static RAMBlock *last_seen_block;

/* This is the last block from where we have sent data */

static RAMBlock *last_sent_block;

static ram_addr_t last_offset;

static unsigned long *migration_bitmap;

static uint64_t migration_dirty_pages;

static uint32_t last_version;

static bool ram_bulk_stage;

static inline

ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,

                                                 ram_addr_t start)

{

    unsigned long base = mr->ram_addr >> TARGET_PAGE_BITS;

    unsigned long nr = base + (start >> TARGET_PAGE_BITS);

    uint64_t mr_size = TARGET_PAGE_ALIGN(memory_region_size(mr));

    unsigned long size = base + (mr_size >> TARGET_PAGE_BITS);

    unsigned long next;

    if (ram_bulk_stage && nr > base) {

        next = nr + 1;

    } else {

        next = find_next_bit(migration_bitmap, size, nr);

    }

    if (next < size) {

        clear_bit(next, migration_bitmap);

        migration_dirty_pages--;

    }

    return (next - base) << TARGET_PAGE_BITS;

}

static inline bool migration_bitmap_set_dirty(MemoryRegion *mr,

                                              ram_addr_t offset)

{

    bool ret;

    int nr = (mr->ram_addr + offset) >> TARGET_PAGE_BITS;

    ret = test_and_set_bit(nr, migration_bitmap);

    if (!ret) {

        migration_dirty_pages++;

    }

    return ret;

}

/* Needs iothread lock! */

static void migration_bitmap_sync(void)

{

    RAMBlock *block;

    ram_addr_t addr;

    uint64_t num_dirty_pages_init = migration_dirty_pages;

    MigrationState *s = migrate_get_current();

    static int64_t start_time;

    static int64_t bytes_xfer_prev;

    static int64_t num_dirty_pages_period;

    int64_t end_time;

    int64_t bytes_xfer_now;

    if (!bytes_xfer_prev) {

        bytes_xfer_prev = ram_bytes_transferred();

    }

    if (!start_time) {

        start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);

    }

    trace_migration_bitmap_sync_start();

    address_space_sync_dirty_bitmap(&address_space_memory);

    QTAILQ_FOREACH(block, &ram_list.blocks, next) {

        for (addr = 0; addr < block->length; addr += TARGET_PAGE_SIZE) {

            if (memory_region_test_and_clear_dirty(block->mr,

                                                   addr, TARGET_PAGE_SIZE,

                                                   DIRTY_MEMORY_MIGRATION)) {

                migration_bitmap_set_dirty(block->mr, addr);

            }

        }

    }

    trace_migration_bitmap_sync_end(migration_dirty_pages

                                    - num_dirty_pages_init);

    num_dirty_pages_period += migration_dirty_pages - num_dirty_pages_init;

    end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);

    /* more than 1 second = 1000 millisecons */

    if (end_time > start_time + 1000) {

        if (migrate_auto_converge()) {

            /* The following detection logic can be refined later. For now:

               Check to see if the dirtied bytes is 50% more than the approx.

               amount of bytes that just got transferred since the last time we

               were in this routine. If that happens >N times (for now N==4)

               we turn on the throttle down logic */

            bytes_xfer_now = ram_bytes_transferred();

            if (s->dirty_pages_rate &&

               (num_dirty_pages_period * TARGET_PAGE_SIZE >

                   (bytes_xfer_now - bytes_xfer_prev)/2) &&

               (dirty_rate_high_cnt++ > 4)) {

                    trace_migration_throttle();

                    mig_throttle_on = true;

                    dirty_rate_high_cnt = 0;

             }

             bytes_xfer_prev = bytes_xfer_now;

        } else {

             mig_throttle_on = false;

        }

        s->dirty_pages_rate = num_dirty_pages_period * 1000

            / (end_time - start_time);

        s->dirty_bytes_rate = s->dirty_pages_rate * TARGET_PAGE_SIZE;

        start_time = end_time;

        num_dirty_pages_period = 0;

    }

}

/*

 * ram_save_block: Writes a page of memory to the stream f

 *

 * Returns:  The number of bytes written.

 *           0 means no dirty pages

 */

static int ram_save_block(QEMUFile *f, bool last_stage)

{

    RAMBlock *block = last_seen_block;

    ram_addr_t offset = last_offset;

    bool complete_round = false;

    int bytes_sent = 0;

    MemoryRegion *mr;

    ram_addr_t current_addr;

    if (!block)

        block = QTAILQ_FIRST(&ram_list.blocks);

    while (true) {

        mr = block->mr;

        offset = migration_bitmap_find_and_reset_dirty(mr, offset);

        if (complete_round && block == last_seen_block &&

            offset >= last_offset) {

            break;

        }

        if (offset >= block->length) {

            offset = 0;

            block = QTAILQ_NEXT(block, next);

            if (!block) {

                block = QTAILQ_FIRST(&ram_list.blocks);

                complete_round = true;

                ram_bulk_stage = false;

            }

        } else {

            int ret;

            uint8_t *p;

            int cont = (block == last_sent_block) ?

                RAM_SAVE_FLAG_CONTINUE : 0;

            p = memory_region_get_ram_ptr(mr) + offset;

            /* In doubt sent page as normal */

            bytes_sent = -1;

            ret = ram_control_save_page(f, block->offset,

                               offset, TARGET_PAGE_SIZE, &bytes_sent);

            if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {

                if (ret != RAM_SAVE_CONTROL_DELAYED) {

                    if (bytes_sent > 0) {

                        acct_info.norm_pages++;

                    } else if (bytes_sent == 0) {

                        acct_info.dup_pages++;

                    }

                }

            } else if (is_zero_page(p)) {

                acct_info.dup_pages++;

                bytes_sent = save_block_hdr(f, block, offset, cont,

                                            RAM_SAVE_FLAG_COMPRESS);

                qemu_put_byte(f, 0);

                bytes_sent++;

            } else if (!ram_bulk_stage && migrate_use_xbzrle()) {

                current_addr = block->offset + offset;

                bytes_sent = save_xbzrle_page(f, p, current_addr, block,

                                              offset, cont, last_stage);

                if (!last_stage) {

                    p = get_cached_data(XBZRLE.cache, current_addr);

                }

            }

            /* XBZRLE overflow or normal page */

            if (bytes_sent == -1) {

                bytes_sent = save_block_hdr(f, block, offset, cont, RAM_SAVE_FLAG_PAGE);

                qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);

                bytes_sent += TARGET_PAGE_SIZE;

                acct_info.norm_pages++;

            }

            /* if page is unmodified, continue to the next */

            if (bytes_sent > 0) {

                last_sent_block = block;

                break;

            }

        }

    }

    last_seen_block = block;

    last_offset = offset;

    return bytes_sent;

}

static uint64_t bytes_transferred;

void acct_update_position(QEMUFile *f, size_t size, bool zero)

{

    uint64_t pages = size / TARGET_PAGE_SIZE;

    if (zero) {

        acct_info.dup_pages += pages;

    } else {

        acct_info.norm_pages += pages;

        bytes_transferred += size;

        qemu_update_position(f, size);

    }

}

static ram_addr_t ram_save_remaining(void)

{

    return migration_dirty_pages;

}

uint64_t ram_bytes_remaining(void)

{

    return ram_save_remaining() * TARGET_PAGE_SIZE;

}

uint64_t ram_bytes_transferred(void)

{

    return bytes_transferred;

}

uint64_t ram_bytes_total(void)

{

    RAMBlock *block;

    uint64_t total = 0;

    QTAILQ_FOREACH(block, &ram_list.blocks, next)

        total += block->length;

    return total;

}

static void migration_end(void)

{

    if (migration_bitmap) {

        memory_global_dirty_log_stop();

        g_free(migration_bitmap);

        migration_bitmap = NULL;

    }

    if (XBZRLE.cache) {

        cache_fini(XBZRLE.cache);

        g_free(XBZRLE.cache);

        g_free(XBZRLE.encoded_buf);

        g_free(XBZRLE.current_buf);

        g_free(XBZRLE.decoded_buf);

        XBZRLE.cache = NULL;

    }

}

static void ram_migration_cancel(void *opaque)

{

    migration_end();

}

static void reset_ram_globals(void)

{

    last_seen_block = NULL;

    last_sent_block = NULL;

    last_offset = 0;

    last_version = ram_list.version;

    ram_bulk_stage = true;

}

#define MAX_WAIT 50 /* ms, half buffered_file limit */

static int ram_save_setup(QEMUFile *f, void *opaque)

{

    RAMBlock *block;

    int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;

    migration_bitmap = bitmap_new(ram_pages);

    bitmap_set(migration_bitmap, 0, ram_pages);

    migration_dirty_pages = ram_pages;

    mig_throttle_on = false;

    dirty_rate_high_cnt = 0;

    if (migrate_use_xbzrle()) {

        XBZRLE.cache = cache_init(migrate_xbzrle_cache_size() /

                                  TARGET_PAGE_SIZE,

                                  TARGET_PAGE_SIZE);

        if (!XBZRLE.cache) {

            DPRINTF("Error creating cache\n");

            return -1;

        }

        XBZRLE.encoded_buf = g_malloc0(TARGET_PAGE_SIZE);

        XBZRLE.current_buf = g_malloc(TARGET_PAGE_SIZE);

        acct_clear();

    }

    qemu_mutex_lock_iothread();

    qemu_mutex_lock_ramlist();

    bytes_transferred = 0;

    reset_ram_globals();

    memory_global_dirty_log_start();

    migration_bitmap_sync();

    qemu_mutex_unlock_iothread();

    qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);

    QTAILQ_FOREACH(block, &ram_list.blocks, next) {

        qemu_put_byte(f, strlen(block->idstr));

        qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));

        qemu_put_be64(f, block->length);

    }

    qemu_mutex_unlock_ramlist();

    ram_control_before_iterate(f, RAM_CONTROL_SETUP);

    ram_control_after_iterate(f, RAM_CONTROL_SETUP);

    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);

    return 0;

}

static int ram_save_iterate(QEMUFile *f, void *opaque)

{

    int ret;

    int i;

    int64_t t0;

    int total_sent = 0;

    qemu_mutex_lock_ramlist();

    if (ram_list.version != last_version) {

        reset_ram_globals();

    }

    ram_control_before_iterate(f, RAM_CONTROL_ROUND);

    t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);

    i = 0;

    while ((ret = qemu_file_rate_limit(f)) == 0) {

        int bytes_sent;

        bytes_sent = ram_save_block(f, false);

        /* no more blocks to sent */

        if (bytes_sent == 0) {

            break;

        }

        total_sent += bytes_sent;

        acct_info.iterations++;

        check_guest_throttling();

        /* we want to check in the 1st loop, just in case it was the 1st time

           and we had to sync the dirty bitmap.

           qemu_get_clock_ns() is a bit expensive, so we only check each some

           iterations

        */

        if ((i & 63) == 0) {

            uint64_t t1 = (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - t0) / 1000000;

            if (t1 > MAX_WAIT) {

                DPRINTF("big wait: %" PRIu64 " milliseconds, %d iterations\n",

                        t1, i);

                break;

            }

        }

        i++;

    }

    qemu_mutex_unlock_ramlist();

    /*

     * Must occur before EOS (or any QEMUFile operation)

     * because of RDMA protocol.

     */

    ram_control_after_iterate(f, RAM_CONTROL_ROUND);

    if (ret < 0) {

        bytes_transferred += total_sent;

        return ret;

    }

    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);

    total_sent += 8;

    bytes_transferred += total_sent;

    return total_sent;

}

static int ram_save_complete(QEMUFile *f, void *opaque)

{

    qemu_mutex_lock_ramlist();

    migration_bitmap_sync();

    ram_control_before_iterate(f, RAM_CONTROL_FINISH);

    /* try transferring iterative blocks of memory */

    /* flush all remaining blocks regardless of rate limiting */

    while (true) {

        int bytes_sent;

        bytes_sent = ram_save_block(f, true);

        /* no more blocks to sent */

        if (bytes_sent == 0) {

            break;

        }

        bytes_transferred += bytes_sent;

    }

    ram_control_after_iterate(f, RAM_CONTROL_FINISH);

    migration_end();

    qemu_mutex_unlock_ramlist();

    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);

    return 0;

}

static uint64_t ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)

{

    uint64_t remaining_size;

    remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;

    if (remaining_size < max_size) {

        qemu_mutex_lock_iothread();

        migration_bitmap_sync();

        qemu_mutex_unlock_iothread();

        remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;

    }

    return remaining_size;

}

static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)

{

    int ret, rc = 0;

    unsigned int xh_len;

    int xh_flags;

    if (!XBZRLE.decoded_buf) {

        XBZRLE.decoded_buf = g_malloc(TARGET_PAGE_SIZE);

    }

    /* extract RLE header */

    xh_flags = qemu_get_byte(f);

    xh_len = qemu_get_be16(f);

    if (xh_flags != ENCODING_FLAG_XBZRLE) {

        fprintf(stderr, "Failed to load XBZRLE page - wrong compression!\n");

        return -1;

    }

    if (xh_len > TARGET_PAGE_SIZE) {

        fprintf(stderr, "Failed to load XBZRLE page - len overflow!\n");

        return -1;

    }

    /* load data and decode */

    qemu_get_buffer(f, XBZRLE.decoded_buf, xh_len);

    /* decode RLE */

    ret = xbzrle_decode_buffer(XBZRLE.decoded_buf, xh_len, host,

                               TARGET_PAGE_SIZE);

    if (ret == -1) {

        fprintf(stderr, "Failed to load XBZRLE page - decode error!\n");

        rc = -1;

    } else  if (ret > TARGET_PAGE_SIZE) {

        fprintf(stderr, "Failed to load XBZRLE page - size %d exceeds %d!\n",

                ret, TARGET_PAGE_SIZE);

        abort();

    }

    return rc;

}

static inline void *host_from_stream_offset(QEMUFile *f,

                                            ram_addr_t offset,

                                            int flags)

{

    static RAMBlock *block = NULL;

    char id[256];

    uint8_t len;

    if (flags & RAM_SAVE_FLAG_CONTINUE) {

        if (!block) {

            fprintf(stderr, "Ack, bad migration stream!\n");

            return NULL;

        }

        return memory_region_get_ram_ptr(block->mr) + offset;

    }

    len = qemu_get_byte(f);

    qemu_get_buffer(f, (uint8_t *)id, len);

    id[len] = 0;

    QTAILQ_FOREACH(block, &ram_list.blocks, next) {

        if (!strncmp(id, block->idstr, sizeof(id)))

            return memory_region_get_ram_ptr(block->mr) + offset;

    }

    fprintf(stderr, "Can't find block %s!\n", id);

    return NULL;

}

/*

 * If a page (or a whole RDMA chunk) has been

 * determined to be zero, then zap it.

 */

void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)

{

    if (ch != 0 || !is_zero_page(host)) {

        memset(host, ch, size);

#ifndef _WIN32

        if (ch == 0 &&

            (!kvm_enabled() || kvm_has_sync_mmu()) &&

            getpagesize() <= TARGET_PAGE_SIZE) {

            qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);

        }

#endif

    }

}

static int ram_load(QEMUFile *f, void *opaque, int version_id)

{

    ram_addr_t addr;

    int flags, ret = 0;

    int error;

    static uint64_t seq_iter;

    seq_iter++;

    if (version_id < 4 || version_id > 4) {

        return -EINVAL;

    }

    do {

        addr = qemu_get_be64(f);

        flags = addr & ~TARGET_PAGE_MASK;

        addr &= TARGET_PAGE_MASK;

        if (flags & RAM_SAVE_FLAG_MEM_SIZE) {

            if (version_id == 4) {

                /* Synchronize RAM block list */

                char id[256];

                ram_addr_t length;

                ram_addr_t total_ram_bytes = addr;

                while (total_ram_bytes) {

                    RAMBlock *block;

                    uint8_t len;

                    len = qemu_get_byte(f);

                    qemu_get_buffer(f, (uint8_t *)id, len);

                    id[len] = 0;

                    length = qemu_get_be64(f);

                    QTAILQ_FOREACH(block, &ram_list.blocks, next) {

                        if (!strncmp(id, block->idstr, sizeof(id))) {

                            if (block->length != length) {

                                fprintf(stderr,

                                        "Length mismatch: %s: " RAM_ADDR_FMT

                                        " in != " RAM_ADDR_FMT "\n", id, length,

                                        block->length);

                                ret =  -EINVAL;

                                goto done;

                            }

                            break;

                        }

                    }

                    if (!block) {

                        fprintf(stderr, "Unknown ramblock \"%s\", cannot "