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.h"

#include "monitor.h"

#include "buffered_file.h"

#include "sysemu.h"

#include "block.h"

#include "qemu_socket.h"

#include "block-migration.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 */

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 */

static MigrationState *migrate_get_current(void)

{

    static MigrationState current_migration = {

        .state = MIG_STATE_SETUP,

        .bandwidth_limit = MAX_THROTTLE,

    };

    return &current_migration;

}

int qemu_start_incoming_migration(const char *uri)

{

    const char *p;

    int ret;

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

        ret = tcp_start_incoming_migration(p);

#if !defined(WIN32)

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

        ret =  exec_start_incoming_migration(p);

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

        ret = unix_start_incoming_migration(p);

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

        ret = fd_start_incoming_migration(p);

#endif

    else {

        fprintf(stderr, "unknown migration protocol: %s\n", uri);

        ret = -EPROTONOSUPPORT;

    }

    return ret;

}

void process_incoming_migration(QEMUFile *f)

{

    if (qemu_loadvm_state(f) < 0) {

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

        exit(0);

    }

    qemu_announce_self();

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

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

    bdrv_invalidate_cache_all();

    if (autostart) {

        vm_start();

    } else {

        runstate_set(RUN_STATE_PRELAUNCH);

    }

}

/* 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;

}

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_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();

        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();

        }

        break;

    case MIG_STATE_COMPLETED:

        info->has_status = true;

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

        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;

}

/* shared migration helpers */

static void migrate_fd_monitor_suspend(MigrationState *s, Monitor *mon)

{

    if (monitor_suspend(mon) == 0) {

        DPRINTF("suspending monitor\n");

    } else {

        monitor_printf(mon, "terminal does not allow synchronous "

                       "migration, continuing detached\n");

    }

}

static int migrate_fd_cleanup(MigrationState *s)

{

    int ret = 0;

    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);

    if (s->file) {

        DPRINTF("closing file\n");

        ret = qemu_fclose(s->file);

        s->file = NULL;

    } else {

        if (s->mon) {

            monitor_resume(s->mon);

        }

    }

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

        close(s->fd);

        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);

}

static void migrate_fd_put_notify(void *opaque)

{

    MigrationState *s = opaque;

    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);

    qemu_file_put_notify(s->file);

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

        migrate_fd_error(s);

    }

}

static ssize_t migrate_fd_put_buffer(void *opaque, const void *data,

                                     size_t size)

{

    MigrationState *s = opaque;

    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));

    if (ret == -EAGAIN) {

        qemu_set_fd_handler2(s->fd, NULL, NULL, migrate_fd_put_notify, s);

    }

    return ret;

}

static void migrate_fd_put_ready(void *opaque)

{

    MigrationState *s = opaque;

    int ret;

    if (s->state != MIG_STATE_ACTIVE) {

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

        return;

    }

    DPRINTF("iterate\n");

    ret = qemu_savevm_state_iterate(s->mon, s->file);

    if (ret < 0) {

        migrate_fd_error(s);

    } else if (ret == 1) {

        int old_vm_running = runstate_is_running();

        DPRINTF("done iterating\n");

        vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);

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

            migrate_fd_error(s);

        } else {

            migrate_fd_completed(s);

        }

        if (s->state != MIG_STATE_COMPLETED) {

            if (old_vm_running) {

                vm_start();

            }

        }

    }

}

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->mon, s->file);

    migrate_fd_cleanup(s);

}

static void migrate_fd_wait_for_unfreeze(void *opaque)

{

    MigrationState *s = opaque;

    int ret;

    DPRINTF("wait for unfreeze\n");

    if (s->state != MIG_STATE_ACTIVE)

        return;

    do {

        fd_set wfds;

        FD_ZERO(&wfds);

        FD_SET(s->fd, &wfds);

        ret = select(s->fd + 1, NULL, &wfds, NULL, NULL);

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

    if (ret == -1) {

        qemu_file_set_error(s->file, -s->get_error(s));

    }

}

static int migrate_fd_close(void *opaque)

{

    MigrationState *s = opaque;

    if (s->mon) {

        monitor_resume(s->mon);

    }

    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);

    return s->close(s);

}

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);

}

void migrate_fd_connect(MigrationState *s)

{

    int ret;

    s->state = MIG_STATE_ACTIVE;

    s->file = qemu_fopen_ops_buffered(s,

                                      s->bandwidth_limit,

                                      migrate_fd_put_buffer,

                                      migrate_fd_put_ready,

                                      migrate_fd_wait_for_unfreeze,

                                      migrate_fd_close);

    DPRINTF("beginning savevm\n");

    ret = qemu_savevm_state_begin(s->mon, s->file, s->blk, s->shared);

    if (ret < 0) {

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

        migrate_fd_error(s);

        return;

    }

    migrate_fd_put_ready(s);

}

static MigrationState *migrate_init(Monitor *mon, int detach, int blk, int inc)

{

    MigrationState *s = migrate_get_current();

    int64_t bandwidth_limit = s->bandwidth_limit;

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

    s->bandwidth_limit = bandwidth_limit;

    s->blk = blk;

    s->shared = inc;

    /* s->mon is used for two things:

       - pass fd in fd migration

       - suspend/resume monitor for not detached migration

    */

    s->mon = mon;

    s->bandwidth_limit = bandwidth_limit;

    s->state = MIG_STATE_SETUP;

    if (!detach) {

        migrate_fd_monitor_suspend(s, mon);

    }

    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);

}

int do_migrate(Monitor *mon, const QDict *qdict, QObject **ret_data)

{

    MigrationState *s = migrate_get_current();

    const char *p;

    int detach = qdict_get_try_bool(qdict, "detach", 0);

    int blk = qdict_get_try_bool(qdict, "blk", 0);

    int inc = qdict_get_try_bool(qdict, "inc", 0);

    const char *uri = qdict_get_str(qdict, "uri");

    int ret;

    if (s->state == MIG_STATE_ACTIVE) {

        monitor_printf(mon, "migration already in progress\n");

        return -1;

    }

    if (qemu_savevm_state_blocked(mon)) {

        return -1;

    }

    if (migration_blockers) {

        Error *err = migration_blockers->data;

        qerror_report_err(err);

        return -1;

    }

    s = migrate_init(mon, detach, blk, inc);

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

        ret = tcp_start_outgoing_migration(s, p);

#if !defined(WIN32)

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

        ret = exec_start_outgoing_migration(s, p);

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

        ret = unix_start_outgoing_migration(s, p);

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

        ret = fd_start_outgoing_migration(s, p);

#endif

    } else {

        monitor_printf(mon, "unknown migration protocol: %s\n", uri);

        ret  = -EINVAL;

    }

    if (ret < 0) {

        monitor_printf(mon, "migration failed: %s\n", strerror(-ret));

        return ret;

    }

    if (detach) {

        s->mon = NULL;

    }

    notifier_list_notify(&migration_state_notifiers, s);

    return 0;

}

void qmp_migrate_cancel(Error **errp)

{

    migrate_fd_cancel(migrate_get_current());

}

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;

}