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/*

 * QEMU live migration

 *

 * Copyright IBM, Corp. 2008

 *

 * Authors:

 *  Anthony Liguori   <aliguori@us.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 "migration/migration.h"

#include "monitor/monitor.h"

#include "migration/qemu-file.h"

#include "sysemu/sysemu.h"

#include "block/block.h"

#include "qemu/sockets.h"

#include "migration/block.h"

#include "qemu/thread.h"

#include "qmp-commands.h"

//#define DEBUG_MIGRATION

#ifdef DEBUG_MIGRATION

#define DPRINTF(fmt, ...) \

    do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)

#else

#define DPRINTF(fmt, ...) \

    do { } while (0)

#endif

enum {

    MIG_STATE_ERROR,

    MIG_STATE_SETUP,

    MIG_STATE_CANCELLED,

    MIG_STATE_ACTIVE,

    MIG_STATE_COMPLETED,

};

#define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */

/* Amount of time to allocate to each "chunk" of bandwidth-throttled

 * data. */

#define BUFFER_DELAY     100

#define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)

/* Migration XBZRLE default cache size */

#define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)

static NotifierList migration_state_notifiers =

    NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);

/* When we add fault tolerance, we could have several

   migrations at once.  For now we don't need to add

   dynamic creation of migration */

MigrationState *migrate_get_current(void)

{

    static MigrationState current_migration = {

        .state = MIG_STATE_SETUP,

        .bandwidth_limit = MAX_THROTTLE,

        .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,

    };

    return &current_migration;

}

void qemu_start_incoming_migration(const char *uri, Error **errp)

{

    const char *p;

    if (strstart(uri, "tcp:", &p))

        tcp_start_incoming_migration(p, errp);

#if !defined(WIN32)

    else if (strstart(uri, "exec:", &p))

        exec_start_incoming_migration(p, errp);

    else if (strstart(uri, "unix:", &p))

        unix_start_incoming_migration(p, errp);

    else if (strstart(uri, "fd:", &p))

        fd_start_incoming_migration(p, errp);

#endif

    else {

        error_setg(errp, "unknown migration protocol: %s\n", uri);

    }

}

static void process_incoming_migration_co(void *opaque)

{

    QEMUFile *f = opaque;

    int ret;

    ret = qemu_loadvm_state(f);

    qemu_set_fd_handler(qemu_get_fd(f), NULL, NULL, NULL);

    qemu_fclose(f);

    if (ret < 0) {

        fprintf(stderr, "load of migration failed\n");

        exit(0);

    }

    qemu_announce_self();

    DPRINTF("successfully loaded vm state\n");

    bdrv_clear_incoming_migration_all();

    /* Make sure all file formats flush their mutable metadata */

    bdrv_invalidate_cache_all();

    if (autostart) {

        vm_start();

    } else {

        runstate_set(RUN_STATE_PAUSED);

    }

}

static void enter_migration_coroutine(void *opaque)

{

    Coroutine *co = opaque;

    qemu_coroutine_enter(co, NULL);

}

void process_incoming_migration(QEMUFile *f)

{

    Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);

    int fd = qemu_get_fd(f);

    assert(fd != -1);

    socket_set_nonblock(fd);

    qemu_set_fd_handler(fd, enter_migration_coroutine, NULL, co);

    qemu_coroutine_enter(co, f);

}

/* amount of nanoseconds we are willing to wait for migration to be down.

 * the choice of nanoseconds is because it is the maximum resolution that

 * get_clock() can achieve. It is an internal measure. All user-visible

 * units must be in seconds */

static uint64_t max_downtime = 30000000;

uint64_t migrate_max_downtime(void)

{

    return max_downtime;

}

MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)

{

    MigrationCapabilityStatusList *head = NULL;

    MigrationCapabilityStatusList *caps;

    MigrationState *s = migrate_get_current();

    int i;

    for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {

        if (head == NULL) {

            head = g_malloc0(sizeof(*caps));

            caps = head;

        } else {

            caps->next = g_malloc0(sizeof(*caps));

            caps = caps->next;

        }

        caps->value =

            g_malloc(sizeof(*caps->value));

        caps->value->capability = i;

        caps->value->state = s->enabled_capabilities[i];

    }

    return head;

}

static void get_xbzrle_cache_stats(MigrationInfo *info)

{

    if (migrate_use_xbzrle()) {

        info->has_xbzrle_cache = true;

        info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));

        info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();

        info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();

        info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();

        info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();

        info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();

    }

}

MigrationInfo *qmp_query_migrate(Error **errp)

{

    MigrationInfo *info = g_malloc0(sizeof(*info));

    MigrationState *s = migrate_get_current();

    switch (s->state) {

    case MIG_STATE_SETUP:

        /* no migration has happened ever */

        break;

    case MIG_STATE_ACTIVE:

        info->has_status = true;

        info->status = g_strdup("active");

        info->has_total_time = true;

        info->total_time = qemu_get_clock_ms(rt_clock)

            - s->total_time;

        info->has_expected_downtime = true;

        info->expected_downtime = s->expected_downtime;

        info->has_ram = true;

        info->ram = g_malloc0(sizeof(*info->ram));

        info->ram->transferred = ram_bytes_transferred();

        info->ram->remaining = ram_bytes_remaining();

        info->ram->total = ram_bytes_total();

        info->ram->duplicate = dup_mig_pages_transferred();

        info->ram->normal = norm_mig_pages_transferred();

        info->ram->normal_bytes = norm_mig_bytes_transferred();

        info->ram->dirty_pages_rate = s->dirty_pages_rate;

        if (blk_mig_active()) {

            info->has_disk = true;

            info->disk = g_malloc0(sizeof(*info->disk));

            info->disk->transferred = blk_mig_bytes_transferred();

            info->disk->remaining = blk_mig_bytes_remaining();

            info->disk->total = blk_mig_bytes_total();

        }

        get_xbzrle_cache_stats(info);

        break;

    case MIG_STATE_COMPLETED:

        get_xbzrle_cache_stats(info);

        info->has_status = true;

        info->status = g_strdup("completed");

        info->total_time = s->total_time;

        info->has_downtime = true;

        info->downtime = s->downtime;

        info->has_ram = true;

        info->ram = g_malloc0(sizeof(*info->ram));

        info->ram->transferred = ram_bytes_transferred();

        info->ram->remaining = 0;

        info->ram->total = ram_bytes_total();

        info->ram->duplicate = dup_mig_pages_transferred();

        info->ram->normal = norm_mig_pages_transferred();

        info->ram->normal_bytes = norm_mig_bytes_transferred();

        break;

    case MIG_STATE_ERROR:

        info->has_status = true;

        info->status = g_strdup("failed");

        break;

    case MIG_STATE_CANCELLED:

        info->has_status = true;

        info->status = g_strdup("cancelled");

        break;

    }

    return info;

}

void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,

                                  Error **errp)

{

    MigrationState *s = migrate_get_current();

    MigrationCapabilityStatusList *cap;

    if (s->state == MIG_STATE_ACTIVE) {

        error_set(errp, QERR_MIGRATION_ACTIVE);

        return;

    }

    for (cap = params; cap; cap = cap->next) {

        s->enabled_capabilities[cap->value->capability] = cap->value->state;

    }

}

/* shared migration helpers */

static int migrate_fd_cleanup(MigrationState *s)

{

    int ret = 0;

    if (s->file) {

        DPRINTF("closing file\n");

        ret = qemu_fclose(s->file);

        s->file = NULL;

    }

    assert(s->fd == -1);

    return ret;

}

void migrate_fd_error(MigrationState *s)

{

    DPRINTF("setting error state\n");

    s->state = MIG_STATE_ERROR;

    notifier_list_notify(&migration_state_notifiers, s);

    migrate_fd_cleanup(s);

}

static void migrate_fd_completed(MigrationState *s)

{

    DPRINTF("setting completed state\n");

    if (migrate_fd_cleanup(s) < 0) {

        s->state = MIG_STATE_ERROR;

    } else {

        s->state = MIG_STATE_COMPLETED;

        runstate_set(RUN_STATE_POSTMIGRATE);

    }

    notifier_list_notify(&migration_state_notifiers, s);

}

ssize_t migrate_fd_put_buffer(MigrationState *s, const void *data,

                              size_t size)

{

    ssize_t ret;

    if (s->state != MIG_STATE_ACTIVE) {

        return -EIO;

    }

    do {

        ret = s->write(s, data, size);

    } while (ret == -1 && ((s->get_error(s)) == EINTR));

    if (ret == -1)

        ret = -(s->get_error(s));

    return ret;

}

static void migrate_fd_cancel(MigrationState *s)

{

    if (s->state != MIG_STATE_ACTIVE)

        return;

    DPRINTF("cancelling migration\n");

    s->state = MIG_STATE_CANCELLED;

    notifier_list_notify(&migration_state_notifiers, s);

    qemu_savevm_state_cancel(s->file);

    migrate_fd_cleanup(s);

}

int migrate_fd_close(MigrationState *s)

{

    int rc = 0;

    if (s->fd != -1) {

        rc = s->close(s);

        s->fd = -1;

    }

    return rc;

}

void add_migration_state_change_notifier(Notifier *notify)

{

    notifier_list_add(&migration_state_notifiers, notify);

}

void remove_migration_state_change_notifier(Notifier *notify)

{

    notifier_remove(notify);

}

bool migration_is_active(MigrationState *s)

{

    return s->state == MIG_STATE_ACTIVE;

}

bool migration_has_finished(MigrationState *s)

{

    return s->state == MIG_STATE_COMPLETED;

}

bool migration_has_failed(MigrationState *s)

{

    return (s->state == MIG_STATE_CANCELLED ||

            s->state == MIG_STATE_ERROR);

}

static MigrationState *migrate_init(const MigrationParams *params)

{

    MigrationState *s = migrate_get_current();

    int64_t bandwidth_limit = s->bandwidth_limit;

    bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];

    int64_t xbzrle_cache_size = s->xbzrle_cache_size;

    memcpy(enabled_capabilities, s->enabled_capabilities,

           sizeof(enabled_capabilities));

    memset(s, 0, sizeof(*s));

    s->bandwidth_limit = bandwidth_limit;

    s->params = *params;

    memcpy(s->enabled_capabilities, enabled_capabilities,

           sizeof(enabled_capabilities));

    s->xbzrle_cache_size = xbzrle_cache_size;

    s->bandwidth_limit = bandwidth_limit;

    s->state = MIG_STATE_SETUP;

    s->total_time = qemu_get_clock_ms(rt_clock);

    return s;

}

static GSList *migration_blockers;

void migrate_add_blocker(Error *reason)

{

    migration_blockers = g_slist_prepend(migration_blockers, reason);

}

void migrate_del_blocker(Error *reason)

{

    migration_blockers = g_slist_remove(migration_blockers, reason);

}

void qmp_migrate(const char *uri, bool has_blk, bool blk,

                 bool has_inc, bool inc, bool has_detach, bool detach,

                 Error **errp)

{

    Error *local_err = NULL;

    MigrationState *s = migrate_get_current();

    MigrationParams params;

    const char *p;

    params.blk = blk;

    params.shared = inc;

    if (s->state == MIG_STATE_ACTIVE) {

        error_set(errp, QERR_MIGRATION_ACTIVE);

        return;

    }

    if (qemu_savevm_state_blocked(errp)) {

        return;

    }

    if (migration_blockers) {

        *errp = error_copy(migration_blockers->data);

        return;

    }

    s = migrate_init(&params);

    if (strstart(uri, "tcp:", &p)) {

        tcp_start_outgoing_migration(s, p, &local_err);

#if !defined(WIN32)

    } else if (strstart(uri, "exec:", &p)) {

        exec_start_outgoing_migration(s, p, &local_err);

    } else if (strstart(uri, "unix:", &p)) {

        unix_start_outgoing_migration(s, p, &local_err);

    } else if (strstart(uri, "fd:", &p)) {

        fd_start_outgoing_migration(s, p, &local_err);

#endif

    } else {

        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");

        return;

    }

    if (local_err) {

        migrate_fd_error(s);

        error_propagate(errp, local_err);

        return;

    }

}

void qmp_migrate_cancel(Error **errp)

{

    migrate_fd_cancel(migrate_get_current());

}

void qmp_migrate_set_cache_size(int64_t value, Error **errp)

{

    MigrationState *s = migrate_get_current();

    /* Check for truncation */

    if (value != (size_t)value) {

        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",

                  "exceeding address space");

        return;

    }

    s->xbzrle_cache_size = xbzrle_cache_resize(value);

}

int64_t qmp_query_migrate_cache_size(Error **errp)

{

    return migrate_xbzrle_cache_size();

}

void qmp_migrate_set_speed(int64_t value, Error **errp)

{

    MigrationState *s;

    if (value < 0) {

        value = 0;

    }

    s = migrate_get_current();

    s->bandwidth_limit = value;

    qemu_file_set_rate_limit(s->file, s->bandwidth_limit);

}

void qmp_migrate_set_downtime(double value, Error **errp)

{

    value *= 1e9;

    value = MAX(0, MIN(UINT64_MAX, value));

    max_downtime = (uint64_t)value;

}

int migrate_use_xbzrle(void)

{

    MigrationState *s;

    s = migrate_get_current();

    return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];

}

int64_t migrate_xbzrle_cache_size(void)

{

    MigrationState *s;

    s = migrate_get_current();

    return s->xbzrle_cache_size;

}

/* migration thread support */

typedef struct QEMUFileBuffered {

    MigrationState *migration_state;

    QEMUFile *file;

    size_t bytes_xfer;

    size_t xfer_limit;

    uint8_t *buffer;

    size_t buffer_size;

    size_t buffer_capacity;

    QemuThread thread;

} QEMUFileBuffered;

static ssize_t buffered_flush(QEMUFileBuffered *s)

{

    size_t offset = 0;

    ssize_t ret = 0;

    DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);

    while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) {

        size_t to_send = MIN(s->buffer_size - offset, s->xfer_limit - s->bytes_xfer);

        ret = migrate_fd_put_buffer(s->migration_state, s->buffer + offset,

                                    to_send);

        if (ret <= 0) {

            DPRINTF("error flushing data, %zd\n", ret);

            break;

        } else {

            DPRINTF("flushed %zd byte(s)\n", ret);

            offset += ret;

            s->bytes_xfer += ret;

        }

    }

    DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);

    memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);

    s->buffer_size -= offset;

    if (ret < 0) {

        return ret;

    }

    return offset;

}

static int buffered_put_buffer(void *opaque, const uint8_t *buf,

                               int64_t pos, int size)

{

    QEMUFileBuffered *s = opaque;

    ssize_t error;

    DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);

    error = qemu_file_get_error(s->file);

    if (error) {

        DPRINTF("flush when error, bailing: %s\n", strerror(-error));

        return error;

    }

    if (size <= 0) {

        return size;

    }

    if (size > (s->buffer_capacity - s->buffer_size)) {

        DPRINTF("increasing buffer capacity from %zu by %zu\n",

                s->buffer_capacity, size + 1024);

        s->buffer_capacity += size + 1024;

        s->buffer = g_realloc(s->buffer, s->buffer_capacity);

    }

    memcpy(s->buffer + s->buffer_size, buf, size);

    s->buffer_size += size;

    return size;

}

static int buffered_close(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    ssize_t ret = 0;

    int ret2;

    DPRINTF("closing\n");

    s->xfer_limit = INT_MAX;

    while (!qemu_file_get_error(s->file) && s->buffer_size) {

        ret = buffered_flush(s);

        if (ret < 0) {

            break;

        }

    }

    ret2 = migrate_fd_close(s->migration_state);

    if (ret >= 0) {

        ret = ret2;

    }

    ret = migrate_fd_close(s->migration_state);

    s->migration_state->complete = true;

    return ret;

}

static int buffered_get_fd(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    return s->migration_state->fd;

}

/*

 * The meaning of the return values is:

 *   0: We can continue sending

 *   1: Time to stop

 *   negative: There has been an error

 */

static int buffered_rate_limit(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    int ret;

    ret = qemu_file_get_error(s->file);

    if (ret) {

        return ret;

    }

    if (s->bytes_xfer > s->xfer_limit) {

        return 1;

    }

    return 0;

}

static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)

{

    QEMUFileBuffered *s = opaque;

    if (qemu_file_get_error(s->file)) {

        goto out;

    }

    if (new_rate > SIZE_MAX) {

        new_rate = SIZE_MAX;

    }

    s->xfer_limit = new_rate / 10;

out:

    return s->xfer_limit;

}

static int64_t buffered_get_rate_limit(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    return s->xfer_limit;

}

static bool migrate_fd_put_ready(MigrationState *s, uint64_t max_size)

{

    int ret;

    uint64_t pending_size;

    bool last_round = false;

    qemu_mutex_lock_iothread();

    if (s->state != MIG_STATE_ACTIVE) {

        DPRINTF("put_ready returning because of non-active state\n");

        qemu_mutex_unlock_iothread();

        return false;

    }

    if (s->first_time) {

        s->first_time = false;

        DPRINTF("beginning savevm\n");

        ret = qemu_savevm_state_begin(s->file, &s->params);

        if (ret < 0) {

            DPRINTF("failed, %d\n", ret);

            migrate_fd_error(s);

            qemu_mutex_unlock_iothread();

            return false;

        }

    }

    DPRINTF("iterate\n");

    pending_size = qemu_savevm_state_pending(s->file, max_size);

    DPRINTF("pending size %lu max %lu\n", pending_size, max_size);

    if (pending_size >= max_size) {

        ret = qemu_savevm_state_iterate(s->file);

        if (ret < 0) {

            migrate_fd_error(s);

        }

    } else {

        int old_vm_running = runstate_is_running();

        int64_t start_time, end_time;

        DPRINTF("done iterating\n");

        start_time = qemu_get_clock_ms(rt_clock);

        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);

        if (old_vm_running) {

            vm_stop(RUN_STATE_FINISH_MIGRATE);

        } else {

            vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);

        }

        if (qemu_savevm_state_complete(s->file) < 0) {

            migrate_fd_error(s);

        } else {

            migrate_fd_completed(s);

        }

        end_time = qemu_get_clock_ms(rt_clock);

        s->total_time = end_time - s->total_time;

        s->downtime = end_time - start_time;

        if (s->state != MIG_STATE_COMPLETED) {

            if (old_vm_running) {

                vm_start();

            }

        }

        last_round = true;

    }

    qemu_mutex_unlock_iothread();

    return last_round;

}

static void *buffered_file_thread(void *opaque)

{

    QEMUFileBuffered *s = opaque;

    int64_t initial_time = qemu_get_clock_ms(rt_clock);

    int64_t max_size = 0;

    bool last_round = false;

    while (true) {

        int64_t current_time = qemu_get_clock_ms(rt_clock);

        if (s->migration_state->complete) {

            break;

        }

        if (current_time >= initial_time + BUFFER_DELAY) {

            uint64_t transferred_bytes = s->bytes_xfer;

            uint64_t time_spent = current_time - initial_time;

            double bandwidth = transferred_bytes / time_spent;

            max_size = bandwidth * migrate_max_downtime() / 1000000;

            DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64

                    " bandwidth %g max_size %" PRId64 "\n",

                    transferred_bytes, time_spent, bandwidth, max_size);

            s->bytes_xfer = 0;

            initial_time = current_time;

        }

        if (!last_round && (s->bytes_xfer >= s->xfer_limit)) {

            /* usleep expects microseconds */

            g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);

        }

        if (buffered_flush(s) < 0) {

            break;

        }

        DPRINTF("file is ready\n");

        if (s->bytes_xfer < s->xfer_limit) {

            DPRINTF("notifying client\n");

            last_round = migrate_fd_put_ready(s->migration_state, max_size);

        }

    }

    g_free(s->buffer);

    g_free(s);

    return NULL;

}

static const QEMUFileOps buffered_file_ops = {

    .get_fd =         buffered_get_fd,

    .put_buffer =     buffered_put_buffer,

    .close =          buffered_close,

    .rate_limit =     buffered_rate_limit,

    .get_rate_limit = buffered_get_rate_limit,

    .set_rate_limit = buffered_set_rate_limit,

};

void migrate_fd_connect(MigrationState *migration_state)

{

    QEMUFileBuffered *s;

    migration_state->state = MIG_STATE_ACTIVE;

    migration_state->first_time = true;

    s = g_malloc0(sizeof(*s));

    s->migration_state = migration_state;

    s->xfer_limit = s->migration_state->bandwidth_limit / XFER_LIMIT_RATIO;

    s->migration_state->complete = false;

    s->file = qemu_fopen_ops(s, &buffered_file_ops);

    migration_state->file = s->file;

    qemu_thread_create(&s->thread, buffered_file_thread, s,

                       QEMU_THREAD_DETACHED);

    notifier_list_notify(&migration_state_notifiers, s);

}