Re: [PATCH RFC V3 4/9] x86/pks: Preserve the PKRS MSR on context switch

[Peter Zijlstra]

On Fri, Oct 16, 2020 at 10:14:10PM -0700, Ira Weiny wrote:
> > so it either needs to
> > explicitly do so, or have an assertion that preemption is indeed
> > disabled.
> 
> However, I don't think I understand clearly.  Doesn't [get|put]_cpu_ptr()
> handle the preempt_disable() for us? 

It does.

> Is it not sufficient to rely on that?

It is.

> Dave's comment seems to be the opposite where we need to eliminate preempt
> disable before calling write_pkrs().
> 
> FWIW I think I'm mistaken in my response to Dave regarding the
> preempt_disable() in pks_update_protection().

Dave's concern is that we're calling with with preemption already
disabled so disabling it again is superfluous.