Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state

[Rik van Riel]

On Tue, 2018-09-18 at 17:07 +0200, Paolo Bonzini wrote:
> On 18/09/2018 16:27, Sebastian Andrzej Siewior wrote:
> > > Likewise, move this to fpu__clear and outside "if
> > > (static_cpu_has(X86_FEATURE_FPU))"?
> > 
> > okay. But if there is no FPU we did not save/restore the pkru
> > value. Is
> > this supposed to be an improvement?
> 
> Honestly it just seemed "more correct", but now that I think about
> it,
> kernel threads should run with PKRU=0.  maybe there's a preexisting
> bug
> that your patch has the occasion to fix.

I don't think it matters what the PKRU state is
for kernel threads, since kernel PTEs should not
be using protection keys anyway.

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