Dr. David Alan Gilbert <
address@hidden> schrieb am Di., 29. Okt. 2019, 03:57:
* Jens Freimann (address@hidden) wrote:
> This patch adds a new migration state called wait-unplug. It is entered
> after the SETUP state if failover devices are present. It will transition
> into ACTIVE once all devices were succesfully unplugged from the guest.
>
> So if a guest doesn't respond or takes long to honor the unplug request
> the user will see the migration state 'wait-unplug'.
>
> In the migration thread we query failover devices if they're are still
> pending the guest unplug. When all are unplugged the migration
> continues. If one device won't unplug migration will stay in wait_unplug
> state.
>
> Signed-off-by: Jens Freimann <address@hidden>
> Acked-by: Cornelia Huck <address@hidden>
I think this is OK, so
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
but see question below
> ---
> include/migration/vmstate.h | 2 ++
> migration/migration.c | 21 +++++++++++++++++++++
> migration/migration.h | 3 +++
> migration/savevm.c | 36 ++++++++++++++++++++++++++++++++++++
> migration/savevm.h | 2 ++
> qapi/migration.json | 5 ++++-
> 6 files changed, 68 insertions(+), 1 deletion(-)
>
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index b9ee563aa4..ac4f46a67d 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -186,6 +186,8 @@ struct VMStateDescription {
> int (*pre_save)(void *opaque);
> int (*post_save)(void *opaque);
> bool (*needed)(void *opaque);
> + bool (*dev_unplug_pending)(void *opaque);
> +
> const VMStateField *fields;
> const VMStateDescription **subsections;
> };
> diff --git a/migration/migration.c b/migration/migration.c
> index 3febd0f8f3..51764f2565 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -52,6 +52,7 @@
> #include "hw/qdev-properties.h"
> #include "monitor/monitor.h"
> #include "net/announce.h"
> +#include "qemu/queue.h"
>
> #define MAX_THROTTLE (32 << 20) /* Migration transfer speed throttling */
>
> @@ -819,6 +820,7 @@ bool migration_is_setup_or_active(int state)
> case MIGRATION_STATUS_SETUP:
> case MIGRATION_STATUS_PRE_SWITCHOVER:
> case MIGRATION_STATUS_DEVICE:
> + case MIGRATION_STATUS_WAIT_UNPLUG:
> return true;
>
> default:
> @@ -954,6 +956,9 @@ static void fill_source_migration_info(MigrationInfo *info)
> case MIGRATION_STATUS_CANCELLED:
> info->has_status = true;
> break;
> + case MIGRATION_STATUS_WAIT_UNPLUG:
> + info->has_status = true;
> + break;
> }
> info->status = s->state;
> }
> @@ -1694,6 +1699,7 @@ bool migration_is_idle(void)
> case MIGRATION_STATUS_COLO:
> case MIGRATION_STATUS_PRE_SWITCHOVER:
> case MIGRATION_STATUS_DEVICE:
> + case MIGRATION_STATUS_WAIT_UNPLUG:
> return false;
> case MIGRATION_STATUS__MAX:
> g_assert_not_reached();
> @@ -3264,6 +3270,19 @@ static void *migration_thread(void *opaque)
>
> qemu_savevm_state_setup(s->to_dst_file);
>
> + if (qemu_savevm_nr_failover_devices()) {
> + migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
> + MIGRATION_STATUS_WAIT_UNPLUG);
> +
> + while (s->state == MIGRATION_STATUS_WAIT_UNPLUG &&
> + !qemu_savevm_state_guest_unplug_pending()) {
> + qemu_sem_timedwait(&s->wait_unplug_sem, 250);
> + }
> +
> + migrate_set_state(&s->state, MIGRATION_STATUS_WAIT_UNPLUG,
> + MIGRATION_STATUS_ACTIVE);
> + }
> +
> s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
> migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
> MIGRATION_STATUS_ACTIVE);
> @@ -3511,6 +3530,7 @@ static void migration_instance_finalize(Object *obj)
> qemu_mutex_destroy(&ms->qemu_file_lock);
> g_free(params->tls_hostname);
> g_free(params->tls_creds);
> + qemu_sem_destroy(&ms->wait_unplug_sem);
> qemu_sem_destroy(&ms->rate_limit_sem);
> qemu_sem_destroy(&ms->pause_sem);
> qemu_sem_destroy(&ms->postcopy_pause_sem);
> @@ -3556,6 +3576,7 @@ static void migration_instance_init(Object *obj)
> qemu_sem_init(&ms->postcopy_pause_rp_sem, 0);
> qemu_sem_init(&ms->rp_state.rp_sem, 0);
> qemu_sem_init(&ms->rate_limit_sem, 0);
> + qemu_sem_init(&ms->wait_unplug_sem, 0);
> qemu_mutex_init(&ms->qemu_file_lock);
> }
>
> diff --git a/migration/migration.h b/migration/migration.h
> index 4f2fe193dc..79b3dda146 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -206,6 +206,9 @@ struct MigrationState
> /* Flag set once the migration thread called bdrv_inactivate_all */
> bool block_inactive;
>
> + /* Migration is waiting for guest to unplug device */
> + QemuSemaphore wait_unplug_sem;
> +
> /* Migration is paused due to pause-before-switchover */
> QemuSemaphore pause_sem;
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 8d95e261f6..0f18dea49e 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1113,6 +1113,42 @@ void qemu_savevm_state_header(QEMUFile *f)
> }
> }
>
> +int qemu_savevm_nr_failover_devices(void)
> +{
> + SaveStateEntry *se;
> + int n = 0;
> +
> + QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> + if (se->vmsd && se->vmsd->dev_unplug_pending) {
> + n++;
> + }
> + }
> +
> + return n;
> +}
> +
> +bool qemu_savevm_state_guest_unplug_pending(void)
> +{
> + int nr_failover_devs;
> + SaveStateEntry *se;
> + bool ret = false;
> + int n = 0;
> +
> + nr_failover_devs = qemu_savevm_nr_failover_devices();
> +
> + QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> + if (!se->vmsd || !se->vmsd->dev_unplug_pending) {
> + continue;
> + }
> + ret = se->vmsd->dev_unplug_pending(se->opaque);
> + if (!ret) {
> + n++;
> + }
> + }
> +
> + return n == nr_failover_devs;
I was expecting != I think? If all the devices say
they've got one pending then doesn't n==nr_failover_devs and
it returns true? But then what happens if only one has one pending?
It's increased when unplug pending is false, which means the device is done. So it returns true when all devices are done with unplugging. It is correct but not obvious. I can reverse it in a follow up to make it more clear.
regards,
Jens
Dave
> +}
> +
> void qemu_savevm_state_setup(QEMUFile *f)
> {
> SaveStateEntry *se;
> diff --git a/migration/savevm.h b/migration/savevm.h
> index 51a4b9caa8..c42b9c80ee 100644
> --- a/migration/savevm.h
> +++ b/migration/savevm.h
> @@ -31,6 +31,8 @@
>
> bool qemu_savevm_state_blocked(Error **errp);
> void qemu_savevm_state_setup(QEMUFile *f);
> +int qemu_savevm_nr_failover_devices(void);
> +bool qemu_savevm_state_guest_unplug_pending(void);
> int qemu_savevm_state_resume_prepare(MigrationState *s);
> void qemu_savevm_state_header(QEMUFile *f);
> int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy);
> diff --git a/qapi/migration.json b/qapi/migration.json
> index e9e7a97c03..b7348d0c8b 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -133,6 +133,9 @@
> # @device: During device serialisation when pause-before-switchover is enabled
> # (since 2.11)
> #
> +# @wait-unplug: wait for device unplug request by guest OS to be completed.
> +# (since 4.2)
> +#
> # Since: 2.3
> #
> ##
> @@ -140,7 +143,7 @@
> 'data': [ 'none', 'setup', 'cancelling', 'cancelled',
> 'active', 'postcopy-active', 'postcopy-paused',
> 'postcopy-recover', 'completed', 'failed', 'colo',
> - 'pre-switchover', 'device' ] }
> + 'pre-switchover', 'device', 'wait-unplug' ] }
>
> ##
> # @MigrationInfo:
> --
> 2.21.0
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK