From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: VMX: call invvpid only when EPT is disabled Date: Thu, 15 Mar 2012 11:53:06 +0200 Message-ID: <4F61BC02.6070607@redhat.com> References: <1331775884.20336.2.camel@offbook> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , Sheng Yang , KVM , lkml To: dave@gnu.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:26520 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752544Ab2COJxN (ORCPT ); Thu, 15 Mar 2012 05:53:13 -0400 In-Reply-To: <1331775884.20336.2.camel@offbook> Sender: kvm-owner@vger.kernel.org List-ID: On 03/15/2012 03:44 AM, Davidlohr Bueso wrote: > From: Davidlohr Bueso > > With EPT enabled it is not required to explicitly run invvpid to invalidate tagged TLB entries, as > KVM does not force vm-exits for cr3 writes and invlpg. Run invvpid only when these instructions > are emulated and shadow pages are used. > > Signed-off-by: Davidlohr Bueso > --- > arch/x86/kvm/vmx.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 2c22fc7..51c7fb9 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2861,12 +2861,13 @@ static void exit_lmode(struct kvm_vcpu *vcpu) > > static void vmx_flush_tlb(struct kvm_vcpu *vcpu) > { > - vpid_sync_context(to_vmx(vcpu)); > if (enable_ept) { > if (!VALID_PAGE(vcpu->arch.mmu.root_hpa)) > return; > ept_sync_context(construct_eptp(vcpu->arch.mmu.root_hpa)); > } > + else > + vpid_sync_context(to_vmx(vcpu)); > } > > static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu) This is wrong, cr3 can still be written from host userspace. To perform this optimization you need to separate the concept of flushing the guest tlb and the host tlb. I doubt it's worthwhile though, won't the ept invalidation flush the entire tlb anyway? -- error compiling committee.c: too many arguments to function