Messages in this thread | | | Subject | Re: [PATCH v2 31/32] KVM: nVMX: Don't flush TLB on nested VM transition with EPT enabled | From | Paolo Bonzini <> | Date | Wed, 18 Mar 2020 11:36:04 +0100 |
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On 17/03/20 19:22, Sean Christopherson wrote: > On Tue, Mar 17, 2020 at 06:18:37PM +0100, Paolo Bonzini wrote: >> On 17/03/20 05:52, Sean Christopherson wrote: >>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c >>> index d816f1366943..a77eab5b0e8a 100644 >>> --- a/arch/x86/kvm/vmx/nested.c >>> +++ b/arch/x86/kvm/vmx/nested.c >>> @@ -1123,7 +1123,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne >>> } >>> >>> if (!nested_ept) >>> - kvm_mmu_new_cr3(vcpu, cr3, false); >>> + kvm_mmu_new_cr3(vcpu, cr3, enable_ept); >> >> Even if enable_ept == false, we could have already scheduled or flushed >> the TLB soon due to one of 1) nested_vmx_transition_tlb_flush 2) >> vpid_sync_context in prepare_vmcs02 3) the processor doing it for >> !enable_vpid. >> >> So for !enable_ept only KVM_REQ_MMU_SYNC is needed, not >> KVM_REQ_TLB_FLUSH_CURRENT I think. Worth adding a TODO? > > Now that you point it out, I think it makes sense to unconditionally pass > %true here, i.e. rely 100% on nested_vmx_transition_tlb_flush() to do the > right thing.
Why doesn't it need KVM_REQ_MMU_SYNC either? All this should be in a comment as well, of course.
(All patches I didn't comment on look good).
Paolo
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