Re: [PATCH] x86/power: Fix 'nosmt' vs. hibernation triple fault during resume
From: Peter Zijlstra
Date: Wed May 29 2019 - 05:07:14 EST
On Tue, May 28, 2019 at 11:31:45PM +0200, Jiri Kosina wrote:
> diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
> index a7d966964c6f..bde8ce1f6c6c 100644
> --- a/arch/x86/power/cpu.c
> +++ b/arch/x86/power/cpu.c
> @@ -299,9 +299,20 @@ int hibernate_resume_nonboot_cpu_disable(void)
> * address in its instruction pointer may not be possible to resolve
> * any more at that point (the page tables used by it previously may
> * have been overwritten by hibernate image data).
> + *
> + * First, make sure that we wake up all the potentially disabled SMT
> + * threads which have been initially brought up and then put into
> + * mwait/cpuidle sleep.
> + * Those will be put to proper (not interfering with hibernation
> + * resume) sleep afterwards, and the resumed kernel will decide itself
> + * what to do with them.
> smp_ops.play_dead = resume_play_dead;
Oooh, teh yuck!, but this explains my confusion from the other thread.
> + ret = cpuhp_smt_enable();
> + if (ret)
> + goto out;
> ret = disable_nonboot_cpus();
> smp_ops.play_dead = play_dead;
> return ret;
I think you can avoid the goto like:
ret = cpuhp_smt_enable();
smp_ops.play_dead = resume_play_dead;
ret = disable_nonboot_cpus();
smp_ops.play_dead = play_dead;
We don't need the play dead change to online CPUs.