Re: [PATCH v2 19/25] KVM: x86/mmu: simplify and/or inline computation of shadow MMU roles

Sean Christopherson
2022-03-08T19:41:54Z

On Tue, Mar 08, 2022, Sean Christopherson wrote:
> On Mon, Feb 21, 2022, Paolo Bonzini wrote:
> > @@ -4822,18 +4798,23 @@ static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
> > {
> > struct kvm_mmu *context = &vcpu->arch.root_mmu;
> > union kvm_mmu_paging_mode cpu_mode = kvm_calc_cpu_mode(vcpu, regs);
> > - union kvm_mmu_page_role root_role =
> > - kvm_calc_shadow_mmu_root_page_role(vcpu, cpu_mode);
> > + union kvm_mmu_page_role root_role;
> >
> > - shadow_mmu_init_context(vcpu, context, cpu_mode, root_role);
> > -}
> > + root_role = cpu_mode.base;
> > + root_role.level = max_t(u32, root_role.level, PT32E_ROOT_LEVEL);
>
> Heh, we have different definitions of "simpler". Can we split the difference
> and do?
>
> /* KVM uses PAE paging whenever the guest isn't using 64-bit paging. */
> if (!____is_efer_lma(regs))
> root_role.level = PT32E_ROOT_LEVEL;

Ha, and then the very next patch stomps all over this. I think this just needs
to add

BUILD_MMU_ROLE_ACCESSOR(ext, efer, lma);

and do

if (!is_efer_lma(context))
root_role.level = PT32E_ROOT_LEVEL;