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);
> -}
> -
> 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
