Re: [PATCH 01/23] KVM: MMU: pass uses_nx directly to reset_shadow_zero_bits_mask

Sean Christopherson
2022-02-07T16:15:19Z

On Sat, Feb 05, 2022, Paolo Bonzini wrote:
> On 2/4/22 18:59, David Matlack wrote:
> > > + reset_shadow_zero_bits_mask(vcpu, context, is_efer_nx(context));
> >
> > Out of curiousity, how does KVM mitigate iTLB multi-hit when shadowing
> > NPT and the guest has not enabled EFER.NX?
>
> You got me worried for a second but iTLB multihit is Intel-only, isn't it?

AFAIK, yes, big Core only. arch/x86/kernel/cpu/common.c sets NO_ITLB_MULTIHIT
for all AMD, Hygon, and Atom CPUs.