Re: [PATCH 0/3] KVM: x86: guest interface for SEV live migration

[Paolo Bonzini]

On 20/04/21 17:15, Sean Christopherson wrote:
> On Tue, Apr 20, 2021, Paolo Bonzini wrote:
> > Do not return the SEV-ES bit from KVM_GET_SUPPORTED_CPUID unless
> > the corresponding module parameter is 1, and clear the memory encryption
> > leaf completely if SEV is disabled.
>
> Impeccable timing, I was planning on refreshing my SEV cleanup series[*] today.
> There's going to be an annoying conflict with the svm_set_cpu_caps() change
> (see below), any objecting to folding your unintentional feedback into my series?

That's fine of course.

> > diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
> > index 888e88b42e8d..e873a60a4830 100644
> > --- a/arch/x86/kvm/cpuid.h
> > +++ b/arch/x86/kvm/cpuid.h
> > @@ -99,6 +99,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
> >   	[CPUID_7_EDX]         = {         7, 0, CPUID_EDX},
> >   	[CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
> >   	[CPUID_12_EAX]        = {0x00000012, 0, CPUID_EAX},
> > +	[CPUID_8000_001F_EAX] = {0x8000001F, 0, CPUID_EAX},
> >   };
> >   
> >   /*
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index cd8c333ed2dc..acdb8457289e 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -923,6 +923,13 @@ static __init void svm_set_cpu_caps(void)
> >   	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
> >   	    boot_cpu_has(X86_FEATURE_AMD_SSBD))
> >   		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
> > +
> > +	/* CPUID 0x8000001F */
> > +	if (sev) {
> > +		kvm_cpu_cap_set(X86_FEATURE_SEV);
> > +		if (sev_es)
> > +			kvm_cpu_cap_set(X86_FEATURE_SEV_ES);
>
> Gah, I completely spaced on the module params in my series, which is more
> problematic than normal because it also moves "sev" and "sev_es" to sev.c.  The
> easy solution is to add sev_set_cpu_caps().

Sounds good.

Paolo