Archipelago » qemu

/*

 * 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"

#include "trace.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", uri);

    }

}

static void process_incoming_migration_co(void *opaque)

{

    QEMUFile *f = opaque;

    int ret;

    ret = qemu_loadvm_state(f);

    qemu_fclose(f);

    if (ret < 0) {

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

        exit(EXIT_FAILURE);

    }

    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);

    }

}

void process_incoming_migration(QEMUFile *f)

{

    Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);

    int fd = qemu_get_fd(f);

    assert(fd != -1);

    qemu_set_nonblock(fd);

    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->skipped = skipped_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->skipped = skipped_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 void migrate_fd_cleanup(void *opaque)

{

    MigrationState *s = opaque;

    qemu_bh_delete(s->cleanup_bh);

    s->cleanup_bh = NULL;

    if (s->file) {

        DPRINTF("closing file\n");

        qemu_mutex_unlock_iothread();

        qemu_thread_join(&s->thread);

        qemu_mutex_lock_iothread();

        qemu_fclose(s->file);

        s->file = NULL;

    }

    assert(s->state != MIG_STATE_ACTIVE);

    if (s->state != MIG_STATE_COMPLETED) {

        qemu_savevm_state_cancel();

    }

    notifier_list_notify(&migration_state_notifiers, s);

}

static void migrate_finish_set_state(MigrationState *s, int new_state)

{

    if (__sync_val_compare_and_swap(&s->state, MIG_STATE_ACTIVE,

                                    new_state) == new_state) {

        trace_migrate_set_state(new_state);

    }

}

void migrate_fd_error(MigrationState *s)

{

    DPRINTF("setting error state\n");

    assert(s->file == NULL);

    s->state = MIG_STATE_ERROR;

    trace_migrate_set_state(MIG_STATE_ERROR);

    notifier_list_notify(&migration_state_notifiers, s);

}

static void migrate_fd_cancel(MigrationState *s)

{

    DPRINTF("cancelling migration\n");

    migrate_finish_set_state(s, MIG_STATE_CANCELLED);

}

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->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;

    trace_migrate_set_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;

    }

    if (value > SIZE_MAX) {

        value = SIZE_MAX;

    }

    s = migrate_get_current();

    s->bandwidth_limit = value;

    if (s->file) {

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

    }

}

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 */

static void *migration_thread(void *opaque)

{

    MigrationState *s = opaque;

    int64_t initial_time = qemu_get_clock_ms(rt_clock);

    int64_t initial_bytes = 0;

    int64_t max_size = 0;

    int64_t start_time = initial_time;

    bool old_vm_running = false;

    DPRINTF("beginning savevm\n");

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

    while (s->state == MIG_STATE_ACTIVE) {

        int64_t current_time;

        uint64_t pending_size;

        if (!qemu_file_rate_limit(s->file)) {

            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 && pending_size >= max_size) {

                qemu_savevm_state_iterate(s->file);

            } else {

                DPRINTF("done iterating\n");

                qemu_mutex_lock_iothread();

                start_time = qemu_get_clock_ms(rt_clock);

                qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);

                old_vm_running = runstate_is_running();

                vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);

                qemu_file_set_rate_limit(s->file, INT_MAX);

                qemu_savevm_state_complete(s->file);

                qemu_mutex_unlock_iothread();

                if (!qemu_file_get_error(s->file)) {

                    migrate_finish_set_state(s, MIG_STATE_COMPLETED);

                    break;

                }

            }

        }

        if (qemu_file_get_error(s->file)) {

            migrate_finish_set_state(s, MIG_STATE_ERROR);

            break;

        }

        current_time = qemu_get_clock_ms(rt_clock);

        if (current_time >= initial_time + BUFFER_DELAY) {

            uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;

            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);

            /* if we haven't sent anything, we don't want to recalculate

               10000 is a small enough number for our purposes */

            if (s->dirty_bytes_rate && transferred_bytes > 10000) {

                s->expected_downtime = s->dirty_bytes_rate / bandwidth;

            }

            qemu_file_reset_rate_limit(s->file);

            initial_time = current_time;

            initial_bytes = qemu_ftell(s->file);

        }

        if (qemu_file_rate_limit(s->file)) {

            /* usleep expects microseconds */

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

        }

    }

    qemu_mutex_lock_iothread();

    if (s->state == MIG_STATE_COMPLETED) {

        int64_t end_time = qemu_get_clock_ms(rt_clock);

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

        s->downtime = end_time - start_time;

        runstate_set(RUN_STATE_POSTMIGRATE);

    } else {

        if (old_vm_running) {

            vm_start();

        }

    }

    qemu_bh_schedule(s->cleanup_bh);

    qemu_mutex_unlock_iothread();

    return NULL;

}

void migrate_fd_connect(MigrationState *s)

{

    s->state = MIG_STATE_ACTIVE;

    trace_migrate_set_state(MIG_STATE_ACTIVE);

    /* This is a best 1st approximation. ns to ms */

    s->expected_downtime = max_downtime/1000000;

    s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);

    qemu_file_set_rate_limit(s->file,

                             s->bandwidth_limit / XFER_LIMIT_RATIO);

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

                       QEMU_THREAD_JOINABLE);

    notifier_list_notify(&migration_state_notifiers, s);

}