Re: [RFC PATCH 23/35] KVM: SVM: Add support for CR4 write traps for an SEV-ES guest

[Paolo Bonzini]

On 15/09/20 00:16, Sean Christopherson wrote:
> > +int kvm_track_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> > +{
> > +	unsigned long old_cr4 = kvm_read_cr4(vcpu);
> > +	unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE |
> > +				   X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE;
> > +
> > +	if (kvm_x86_ops.set_cr4(vcpu, cr4))
> > +		return 1;
> Pretty much all the same comments as EFER and CR0, e.g. call svm_set_cr4()
> directly instead of bouncing through kvm_x86_ops.  And with that, this can
> be called __kvm_set_cr4() to be consistent with __kvm_set_cr0().

I agree with calling svm_set_cr4 directly, but then this should be 
kvm_post_set_cr4.

Paolo

> > +
> > +	if (((cr4 ^ old_cr4) & pdptr_bits) ||
> > +	    (!(cr4 & X86_CR4_PCIDE) && (old_cr4 & X86_CR4_PCIDE)))
> > +		kvm_mmu_reset_context(vcpu);
> > +
> > +	if ((cr4 ^ old_cr4) & (X86_CR4_OSXSAVE | X86_CR4_PKE))
> > +		kvm_update_cpuid_runtime(vcpu);
> > +
> > +	return 0;
> > +}