Re: [Xen-devel] [V2 PATCH 1/9] x86/hvm: pkeys, add pkeys support for cpuid handling

["Han, Huaitong" <huaitong.han@xxxxxxxxx>]

On Wed, 2015-12-02 at 04:06 -0700, Jan Beulich wrote:

> > > )
> > > +            *ecx &= ~cpufeat_mask(X86_FEATURE_PKU);
> > > +
> > > +        if ( (count == 0) && cpu_has_pku )
> > > +            *ecx |= (v->arch.hvm_vcpu.guest_cr[4] & X86_CR4_PKE)
> > > ?
> > > +                     cpufeat_mask(X86_FEATURE_OSPKE) : 0;
> > 
> > This is still buggy.  cpu_has_pku has no relevance to whether OSPKE
> > becomes visible.
> > 
> > Visibility of OSPKE is determined solely by v
> > ->arch.hvm_vcpu.guest_cr[4]
> > & X86_CR4_PKE and nothing else.
> 
> Actually I wouldn't mind guarding against the case where the CR4 flag
> is wrongly set for whatever reason, but that ought to check the PKU
> bit in *ecx, not the host flag. Same applies to the cpu_has_xsave
> check - this too should check the guest flag, not the host one.
I will add guest_cpuid_has_xxx functions.
> 
> Jan
> 
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