Re: [PATCH v5 08/19] KVM:x86: Report KVM supported CET MSRs as to-be-saved

[Yang, Weijiang]

On 8/5/2023 2:55 AM, Sean Christopherson wrote:
> On Thu, Aug 03, 2023, Yang Weijiang wrote:
> > Add all CET MSRs including the synthesized GUEST_SSP to report list.
> > PL{0,1,2}_SSP are independent to host XSAVE management with later
> > patches. MSR_IA32_U_CET and MSR_IA32_PL3_SSP are XSAVE-managed on
> > host side. MSR_IA32_S_CET/MSR_IA32_INT_SSP_TAB/MSR_KVM_GUEST_SSP
> > are not XSAVE-managed.
> >
> > [...]
> >   	}
> > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> > index 82e3dafc5453..6e6292915f8c 100644
> > --- a/arch/x86/kvm/x86.h
> > +++ b/arch/x86/kvm/x86.h
> > @@ -362,6 +362,16 @@ static inline bool kvm_mpx_supported(void)
> >   		== (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
> >   }
> >   
> > +#define CET_XSTATE_MASK (XFEATURE_MASK_CET_USER)
> This is funky.  As of this patch, KVM reports MSR_IA32_S_CET, a supervisor MSR,
> but does not require XFEATURE_MASK_CET_KERNEL.  That eventually comes along with
> "KVM:x86: Enable guest CET supervisor xstate bit support", but as of this patch
> KVM is busted.
>
> The whole cpuid_count() code in that patch shouldn't exist, so the easiest thing
> is to just fold the KVM_SUPPORTED_XSS and CET_XSTATE_MASK changes from that patch
> into this one.
I screwed it up when tried to make it clearer :-/
Will do it, thanks!