Re: [PATCH v3 2/3] x86/smp native_play_dead: Prefer cpuidle_play_dead() over mwait_play_dead()

[Peter Zijlstra]

On Wed, Nov 13, 2024 at 05:11:38PM +0530, Gautham R. Shenoy wrote:

> AMD platforms won't be using FFH based states for offlined CPUs. We
> prefer IO based states when available, and HLT otherwise.
> 
> > 
> > Robustly we'd teach the ACPI driver about FFh and set enter_dead on
> > every state -- but we'd have to double check that with AMD.
> 
> Works for us as long as those FFh states aren't used for play_dead on
> AMD platforms.

AFAIU AMD doesn't want to use MWAIT -- ever, not only for offline.
Confirm?

But if it were to use MWAIT for regular idle, then surely it's OK for
offline too, right?