Re: [PATCH] KVM: SVM: Propagate Translation Cache Extensions to the guest

Sean Christopherson
2026-03-06T22:40:55Z

On Fri, Mar 06, 2026, Yosry Ahmed wrote:
> On Fri, Mar 6, 2026 at 8:19 AM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Fri, Mar 06, 2026, Yosry Ahmed wrote:
> > > From: Venkatesh Srinivas <venkateshs@chromium.org>
> > >
> > > TCE augments the behavior of TLB invalidating instructions (INVLPG,
> > > INVLPGB, and INVPCID) to only invalidate translations for relevant
> > > intermediate mappings to the address range, rather than ALL intermdiate
> > > translations.
> > >
> > > The Linux kernel has been setting EFER.TCE if supported by the CPU since
> > > commit 440a65b7d25f ("x86/mm: Enable AMD translation cache extensions"),
> > > as it may improve performance.
> > >
> > > KVM does not need to do anything to virtualize the feature,
> >
> > Please back this up with actual analysis.
>
> Something like this?
>
> If a TLB invalidating instruction is not intercepted, it will behave
> according to the guest's setting of EFER.TCE as the value will be
> loaded on VM-Enter. Otherwise, KVM's emulation may invalidate more TLB
> entries, which is perfectly fine as the CPU is allowed to invalidate
> more TLB entries that it strictly needs to.

Ya, LGTM.