Re: [NEEDS-REVIEW] [PATCH V3 04/10] x86/pks: Preserve the PKRS MSR on context switch

Ira Weiny
2020-12-18T04:10:16Z

On Thu, Dec 17, 2020 at 12:41:50PM -0800, Dave Hansen wrote:
> On 11/6/20 3:29 PM, ira.weiny@intel.com wrote:
> > void disable_TSC(void)
> > @@ -644,6 +668,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
> >
> > if ((tifp ^ tifn) & _TIF_SLD)
> > switch_to_sld(tifn);
> > +
> > + pks_sched_in();
> > }
>
> Does the selftest for this ever actually schedule()?

At this point I'm not sure. This code has been in since the beginning. So its
seen a lot of soak time.

>
> I see it talking about context switching, but I don't immediately see
> how it would.

We were trying to force parent and child to run on the same CPU. I suspect
something is wrong in the timing of that test.

Ira