Re: [PATCH v2 01/25] KVM: x86/mmu: avoid indirect call for get_cr3

Paolo Bonzini
2022-03-08T16:43:22Z

On 3/8/22 17:32, Sean Christopherson wrote:
>
> Aha! An idea that would provide line of sight to avoiding retpoline in all cases
> once we use static_call() for nested_ops, which I really want to do... Drop the
> mmu hook entirely and replace it with:
>
> static inline kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu)
> {
> if (!mmu_is_nested(vcpu))
> return kvm_read_cr3(vcpu);
> else
> return kvm_x86_ops.nested_ops->get_guest_pgd(vcpu);
> }

Makes sense, but I think you mean

static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu,
struct kvm_mmu *mmu)
{
if (unlikely(vcpu == &vcpu->arch.guest_mmu))
return kvm_x86_ops.nested_ops->get_guest_pgd(vcpu);
else
return kvm_read_cr3(vcpu);
}

?

Paolo