On Thu, Feb 22, 2024 at 05:12:53PM +0800, Peter Xu wrote:
> On Wed, Feb 21, 2024 at 04:20:07PM -0500, Steven Sistare wrote:
> > On 2/20/2024 2:33 AM, Peter Xu wrote:
> > > On Thu, Feb 08, 2024 at 10:54:03AM -0800, Steve Sistare wrote:
> > >> When migration for cpr is initiated, stop the vm and set state
> > >> RUN_STATE_FINISH_MIGRATE before ram is saved. This eliminates the
> > >> possibility of ram and device state being out of sync, and guarantees
> > >> that a guest in the suspended state remains suspended, because qmp_cont
> > >> rejects a cont command in the RUN_STATE_FINISH_MIGRATE state.
> > >>
> > >> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> > >> ---
> > >> include/migration/misc.h | 1 +
> > >> migration/migration.c | 32 +++++++++++++++++++++++++-------
> > >> 2 files changed, 26 insertions(+), 7 deletions(-)
> > >>
> > >> diff --git a/include/migration/misc.h b/include/migration/misc.h
> > >> index 6dc234b..54c99a3 100644
> > >> --- a/include/migration/misc.h
> > >> +++ b/include/migration/misc.h
> > >> @@ -60,6 +60,7 @@ void migration_object_init(void);
> > >> void migration_shutdown(void);
> > >> bool migration_is_idle(void);
> > >> bool migration_is_active(MigrationState *);
> > >> +bool migrate_mode_is_cpr(MigrationState *);
> > >>
> > >> typedef enum MigrationEventType {
> > >> MIG_EVENT_PRECOPY_SETUP,
> > >> diff --git a/migration/migration.c b/migration/migration.c
> > >> index d1fce9e..fc5c587 100644
> > >> --- a/migration/migration.c
> > >> +++ b/migration/migration.c
> > >> @@ -1603,6 +1603,11 @@ bool migration_is_active(MigrationState *s)
> > >> s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
> > >> }
> > >>
> > >> +bool migrate_mode_is_cpr(MigrationState *s)
> > >> +{
> > >> + return s->parameters.mode == MIG_MODE_CPR_REBOOT;
> > >> +}
> > >> +
> > >> int migrate_init(MigrationState *s, Error **errp)
> > >> {
> > >> int ret;
> > >> @@ -2651,13 +2656,14 @@ static int
> > >> migration_completion_precopy(MigrationState *s,
> > >> bql_lock();
> > >> migration_downtime_start(s);
> > >>
> > >> - s->vm_old_state = runstate_get();
> > >> - global_state_store();
> > >> -
> > >> - ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
> > >> - trace_migration_completion_vm_stop(ret);
> > >> - if (ret < 0) {
> > >> - goto out_unlock;
> > >> + if (!migrate_mode_is_cpr(s)) {
> > >> + s->vm_old_state = runstate_get();
> > >> + global_state_store();
> > >> + ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
> > >> + trace_migration_completion_vm_stop(ret);
> > >> + if (ret < 0) {
> > >> + goto out_unlock;
> > >> + }
> > >> }
> > >>
> > >> ret = migration_maybe_pause(s, current_active_state,
> > >> @@ -3576,6 +3582,7 @@ void migrate_fd_connect(MigrationState *s, Error
> > >> *error_in)
> > >> Error *local_err = NULL;
> > >> uint64_t rate_limit;
> > >> bool resume = s->state == MIGRATION_STATUS_POSTCOPY_PAUSED;
> > >> + int ret;
> > >>
> > >> /*
> > >> * If there's a previous error, free it and prepare for another one.
> > >> @@ -3651,6 +3658,17 @@ void migrate_fd_connect(MigrationState *s, Error
> > >> *error_in)
> > >> goto fail;
> > >> }
> > >>
> > >> + if (migrate_mode_is_cpr(s)) {
> > >> + s->vm_old_state = runstate_get();
> > >> + global_state_store();
> > >> + ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
> > >> + trace_migration_completion_vm_stop(ret);
> > >> + if (ret < 0) {
> > >> + error_setg(&local_err, "migration_stop_vm failed, error
> > >> %d", -ret);
> > >> + goto fail;
> > >> + }
> > >> + }
> > >
> > > Could we have a helper function for the shared codes?
> >
> > I propose to add code to migration_stop_vm to make it the helper. Some
> > call sites emit
> > more traces (via migration_stop_vm) as a result of my refactoring,
>
> This should be fine.
>
> > and postcopy start sets
> > vm_old_state, which is not used thereafter in that path. Those changes
> > seem harmless to me.
>
> Not only harmless, I think it was a bug to not set vm_old_state in
> postcopy_start().. See:
>
> https://issues.redhat.com/browse/RHEL-18061
>
> I suspect that was the cause.
>
> > Tell me what you think:
>
> I'll have a closer look later, but so far it looks all good.
>
> Thanks,
>
> >
> > -------------------------------------------------------
> > diff --git a/migration/migration.c b/migration/migration.c
> > index fc5c587..30d2b08 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -107,12 +107,6 @@ static int migration_maybe_pause(MigrationState *s,
> > static void migrate_fd_cancel(MigrationState *s);
> > static bool close_return_path_on_source(MigrationState *s);
> >
> > -static void migration_downtime_start(MigrationState *s)
> > -{
> > - trace_vmstate_downtime_checkpoint("src-downtime-start");
> > - s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> > -}
Ah.. one more thing: would you mind keep this helper even if it can be
squashed when sending formal patch? I want to keep downtime start/end
super clear and paired as they're important hook points. It should be
inlined anyway by the compiler.
> > -
> > static void migration_downtime_end(MigrationState *s)
> > {
> > int64_t now = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> > @@ -161,11 +155,20 @@ static gint page_request_addr_cmp(gconstpointer ap,
> > gconstpo
> > return (a > b) - (a < b);
> > }
> >
> > -int migration_stop_vm(RunState state)
> > +static int migration_stop_vm(MigrationState *s, RunState state)
> > {
> > - int ret = vm_stop_force_state(state);
> > + int ret;
> > +
> > + trace_vmstate_downtime_checkpoint("src-downtime-start");
> > + s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> > +
> > + s->vm_old_state = runstate_get();
> > + global_state_store();
> > +
> > + ret = vm_stop_force_state(state);
> >
> > trace_vmstate_downtime_checkpoint("src-vm-stopped");
> > + trace_migration_completion_vm_stop(ret);
> >
> > return ret;
> > }
> > @@ -2454,10 +2457,7 @@ static int postcopy_start(MigrationState *ms, Error
> > **errp)
> > bql_lock();
> > trace_postcopy_start_set_run();
> >
> > - migration_downtime_start(ms);
> > -
> > - global_state_store();
> > - ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
> > + ret = migration_stop_vm(ms, RUN_STATE_FINISH_MIGRATE);
> > if (ret < 0) {
> > goto fail;
> > }
> > @@ -2654,13 +2654,9 @@ static int
> > migration_completion_precopy(MigrationState *s,
> > int ret;
> >
> > bql_lock();
> > - migration_downtime_start(s);
> >
> > if (!migrate_mode_is_cpr(s)) {
> > - s->vm_old_state = runstate_get();
> > - global_state_store();
> > - ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
> > - trace_migration_completion_vm_stop(ret);
> > + ret = migration_stop_vm(s, RUN_STATE_FINISH_MIGRATE);
> > if (ret < 0) {
> > goto out_unlock;
> > }
> > @@ -3498,15 +3494,10 @@ static void *bg_migration_thread(void *opaque)
> > s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
> >
> > trace_migration_thread_setup_complete();
> > - migration_downtime_start(s);
> >
> > bql_lock();
> >
> > - s->vm_old_state = runstate_get();
> > -
> > - global_state_store();
> > - /* Forcibly stop VM before saving state of vCPUs and devices */
> > - if (migration_stop_vm(RUN_STATE_PAUSED)) {
> > + if (migration_stop_vm(s, RUN_STATE_PAUSED)) {
> > goto fail;
> > }
> > /*
> > @@ -3659,10 +3650,7 @@ void migrate_fd_connect(MigrationState *s, Error
> > *error_in)
> > }
> >
> > if (migrate_mode_is_cpr(s)) {
> > - s->vm_old_state = runstate_get();
> > - global_state_store();
> > - ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
> > - trace_migration_completion_vm_stop(ret);
> > + ret = migration_stop_vm(s, RUN_STATE_FINISH_MIGRATE);
> > if (ret < 0) {
> > error_setg(&local_err, "migration_stop_vm failed, error %d",
> > -ret);
> > goto fail;
> > diff --git a/migration/migration.h b/migration/migration.h
> > index aef8afb..65c0b61 100644
> > --- a/migration/migration.h
> > +++ b/migration/migration.h
> > @@ -541,6 +541,4 @@ int migration_rp_wait(MigrationState *s);
> > */
> > void migration_rp_kick(MigrationState *s);
> >
> > -int migration_stop_vm(RunState state);
> > -
> > #endif
> > -------------------------------------------------------
> >
> > - Steve
> >
>
> --
> Peter Xu
--
Peter Xu
