Re: [PATCH v6 1/2] KVM: x86/cpuid: generalize kvm_update_kvm_cpuid_base() and also capture limit

[Paul Durrant]

On 05/01/2023 18:09, Sean Christopherson wrote:
> On Thu, Jan 05, 2023, Paul Durrant wrote:
> > On 04/01/2023 19:34, Sean Christopherson wrote:
> > > Since the struct is a 64-bit value, what about making this a pure getter that
> > > returns a copy?
> > >
> > > static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
> > > 							    const char *sig)
> > > {
> > > 	struct kvm_hypervisor_cpuid cpuid = {};
> > > 	struct kvm_cpuid_entry2 *entry;
> > > 	u32 function;
> > >
> > > 	for_each_possible_hypervisor_cpuid_base(cpuid.base) {
> > > 		entry = kvm_find_cpuid_entry(vcpu, function);
> > >
> > > 		if (entry) {
> > > 			u32 signature[3];
> > >
> > > 			signature[0] = entry->ebx;
> > > 			signature[1] = entry->ecx;
> > > 			signature[2] = entry->edx;
> > >
> > > 			if (!memcmp(signature, sig, sizeof(signature))) {
> > > 				cpuid.base = function;
> > > 				cpuid.limit = entry->eax;
> > > 				break;
> > > 			}
> > > 		}
> > > 	}
> > >
> > > 	return cpuid;
> > > }
> > >
> > >
> > > 	vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
> > > 	vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
> >
> > Yes, if that's preferable then no problem.
>
> I like it (obviously), but it's probably worth waiting a few days to see what
> others think before posting a new version.

I think it's cleaner too, and I already did the typing so I may as well 
post. I don't think anyone else has expressed any strong opinions on the 
code either way.

Paul