Dr. David Alan Gilbert <dgilb...@redhat.com> schrieb am Di., 29. Okt. 2019,
03:57:
> * Jens Freimann (jfreim...@redhat.com) 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 <jfreim...@redhat.com>
> > Acked-by: Cornelia Huck <coh...@redhat.com>
>
> I think this is OK, so
>
>
> Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
>
> 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 / dgilb...@redhat.com / Manchester, UK
>
>
>
