On Tue, Aug 29, 2023 at 11:18:00AM -0700, Steve Sistare wrote:
> Do not wake a suspended guest during bg_migration.
>
> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> ---
> migration/migration.c | 12 +++++-------
> softmmu/runstate.c | 1 +
> 2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index a9ecb66..303d5a6 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -3064,7 +3064,9 @@ static void bg_migration_vm_start_bh(void *opaque)
> qemu_bh_delete(s->vm_start_bh);
> s->vm_start_bh = NULL;
>
> - vm_start();
> + if (!runstate_check(RUN_STATE_SUSPENDED)) {
> + vm_start();
> + }
> s->downtime = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - s->downtime_start;
> }
>
> @@ -3134,16 +3136,12 @@ static void *bg_migration_thread(void *opaque)
>
> qemu_mutex_lock_iothread();
>
> - /*
> - * If VM is currently in suspended state, then, to make a valid runstate
> - * transition in vm_stop_force_state() we need to wakeup it up.
> - */
> - qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
> s->vm_old_state = runstate_get();
>
> global_state_store();
> /* Forcibly stop VM before saving state of vCPUs and devices */
> - if (vm_stop_force_state(RUN_STATE_PAUSED)) {
> + if (!runstate_check(RUN_STATE_SUSPENDED) &&
> + vm_stop_force_state(RUN_STATE_PAUSED)) {
IIUC we need the vm_stop even for SUSPENDED? I think we need to make sure
all backends are stopped before we start wr-protect the guest pages, so
when wr-protect happens the guest pages should be in a consistent state.
I'd think it proper to juse reuse the helper you introduced in the previous
patches, but maybe you have a reason to not do so (I didn't see it
mentioned anywhere, though)?
> goto fail;
> }
> /*
> diff --git a/softmmu/runstate.c b/softmmu/runstate.c
> index 21d7407..4417527 100644
> --- a/softmmu/runstate.c
> +++ b/softmmu/runstate.c
> @@ -163,6 +163,7 @@ static const RunStateTransition
> runstate_transitions_def[] = {
> { RUN_STATE_SUSPENDED, RUN_STATE_FINISH_MIGRATE },
> { RUN_STATE_SUSPENDED, RUN_STATE_PRELAUNCH },
> { RUN_STATE_SUSPENDED, RUN_STATE_COLO},
> + { RUN_STATE_SUSPENDED, RUN_STATE_PAUSED },
>
> { RUN_STATE_WATCHDOG, RUN_STATE_RUNNING },
> { RUN_STATE_WATCHDOG, RUN_STATE_FINISH_MIGRATE },
> --
> 1.8.3.1
>
--
Peter Xu
