On Fri, Feb 28, 2025 at 08:58:04PM -0500, Maxim Levitsky wrote: > On Wed, 2025-02-05 at 18:23 +0000, Yosry Ahmed wrote: > > KVM_REQ_TLB_FLUSH is used to flush all TLB entries for all contexts > > (e.g. in kvm_flush_remote_tlbs()). Flush both L1 and L2 ASIDs in > > svm_flush_tlb_all() to handle it appropriately. > > > > This is currently not required as nested transitions do unconditional > > TLB flushes, but this is a step toward eliminating that. > > > > Signed-off-by: Yosry Ahmed <yosry.ahmed@xxxxxxxxx> > > --- > > arch/x86/kvm/svm/nested.c | 1 - > > arch/x86/kvm/svm/svm.c | 4 +++- > > 2 files changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c > > index 0e9b0592c1f83..0735177b95a1d 100644 > > --- a/arch/x86/kvm/svm/nested.c > > +++ b/arch/x86/kvm/svm/nested.c > > @@ -491,7 +491,6 @@ static void nested_svm_entry_tlb_flush(struct kvm_vcpu *vcpu) > > * TODO: optimize unconditional TLB flush/MMU sync. A partial list of > > * things to fix before this can be conditional: > > * > > - * - Flush TLBs for both L1 and L2 remote TLB flush > > * - Honor L1's request to flush an ASID on nested VMRUN > > * - Sync nested NPT MMU on VMRUN that flushes L2's ASID[*] > > * - Don't crush a pending TLB flush in vmcb02 on nested VMRUN > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > > index 9e29f87d3bd93..8342c7eadbba8 100644 > > --- a/arch/x86/kvm/svm/svm.c > > +++ b/arch/x86/kvm/svm/svm.c > > @@ -4044,7 +4044,9 @@ static void svm_flush_tlb_all(struct kvm_vcpu *vcpu) > > if (WARN_ON_ONCE(svm_hv_is_enlightened_tlb_enabled(vcpu))) > > hv_flush_remote_tlbs(vcpu->kvm); > > > > - svm_flush_tlb_asid(vcpu, svm->current_vmcb); > > + svm_flush_tlb_asid(vcpu, &svm->vmcb01); > > + if (svm->nested.initialized) > > + svm_flush_tlb_asid(vcpu, &svm->nested.vmcb02); > > } > > This makes sense. > > Note that this doesn't really flush the ASID used, but rather ensures > that we will flush it on next entry via that vmcb. (because of new asid, > that will be picked, or because we set tlb_ctl in that vmcb) Right, what I mean by 'flush' here is to setup the flush. For SVM all flushes are done on VM-enter anyway. > > Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Thanks!
