Re: [PATCH v3 05/27] KVM: SVM: Add helpers to set/clear ASID flush in VMCB

[Yosry Ahmed]

On Wed, Oct 14, 2026 at 3:00 PM Jim Mattson <jmattson@xxxxxxxxxx> wrote:
>
> On Mon, Oct 12, 2026 at 4:36 PM Yosry Ahmed <yosry@xxxxxxxxxx> wrote:
> >
> > Introduce set/clear helpers to set tlb_ctl to
> > TLB_CONTROL_FLUSH_ASID or TLB_CONTROL_DO_NOTHING. Incoming changes will
> > eliminate the use of TLB_CONTROL_FLUSH_ALL_ASID except as a fallback
> > when FLUSHBYASID is not available, so the helpers will create a common
> > path for this.
>
> No functional change intended? :)
>
> >
> > Signed-off-by: Yosry Ahmed <yosry@xxxxxxxxxx>
> > ---
> >  arch/x86/kvm/svm/nested.c |  2 +-
> >  arch/x86/kvm/svm/sev.c    |  2 +-
> >  arch/x86/kvm/svm/svm.c    |  4 ++--
> >  arch/x86/kvm/svm/svm.h    | 10 ++++++++++
> >  4 files changed, 14 insertions(+), 4 deletions(-)
> >
> [ ... ]
> > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> > index 6d0242966dc87..ba5077b9838c0 100644
> > --- a/arch/x86/kvm/svm/svm.h
> > +++ b/arch/x86/kvm/svm/svm.h
> > @@ -480,6 +480,16 @@ static inline void vmcb_set_gpat(struct vmcb *vmcb, u64 data)
> >         vmcb_mark_dirty(vmcb, VMCB_NPT);
> >  }
> >
> > +static inline void vmcb_set_flush_asid(struct vmcb *vmcb)
> > +{
> > +       vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
> > +}
> > +
> > +static inline void vmcb_clr_flush_asid(struct vmcb *vmcb)
>
> The name of this function makes it sound like the inverse of
> vmcb_set_flush_asid(), which it isn't. Maybe vmcb_clr_tlb_ctl()?

Why not? vmcb_set_flush_asid() sets FLUSH_ASID and
vmcb_clr_flush_asid() clears it, right?

>
> > +{
> > +       vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
> > +}
> > +
> >  static __always_inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
> >  {
> >         return container_of(vcpu, struct vcpu_svm, vcpu);
> > --
> > 2.56.0.385.gd3acb90ef8-goog
> >