From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2] KVM: nVMX/nSVM: Don't intercept #UD when running L2 Date: Mon, 6 Nov 2017 15:16:34 +0100 Message-ID: References: <1509977710-29704-1-git-send-email-liran.alon@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: jmattson@google.com, idan.brown@oracle.com, Konrad Rzeszutek Wilk To: Liran Alon , rkrcmar@redhat.com, kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37341 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250AbdKFOQi (ORCPT ); Mon, 6 Nov 2017 09:16:38 -0500 In-Reply-To: <1509977710-29704-1-git-send-email-liran.alon@oracle.com> Content-Language: en-US Sender: kvm-owner@vger.kernel.org List-ID: On 06/11/2017 15:15, Liran Alon wrote: > When running L2, #UD should be intercepted by L1 or just forwarded > directly to L2. It should not reach L0 x86 emulator. > Therefore, set intercept for #UD only based on L1 exception-bitmap. > > Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure > it is never reached while running L2. > > This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while > in guest mode") by removing an unnecessary exit from L2 to L0 on #UD > when L1 doesn't intercept it. > > In addition, SVM L0 #UD intercept handler doesn't handle correctly the > case it is raised from L2. In this case, it should forward the #UD to > guest instead of x86 emulator. As done in VMX #UD intercept handler. > This commit fixes this issue as-well. > > Signed-off-by: Liran Alon > Reviewed-by: Nikita Leshenko > Reviewed-by: Konrad Rzeszutek Wilk > Signed-off-by: Konrad Rzeszutek Wilk > --- > arch/x86/kvm/svm.c | 9 ++++++++- > arch/x86/kvm/vmx.c | 9 ++++----- > 2 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 0e68f0b3cbf7..e49d44afbe9a 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -361,6 +361,7 @@ static void recalc_intercepts(struct vcpu_svm *svm) > { > struct vmcb_control_area *c, *h; > struct nested_state *g; > + u32 h_intercept_exceptions; > > mark_dirty(svm->vmcb, VMCB_INTERCEPTS); > > @@ -371,9 +372,14 @@ static void recalc_intercepts(struct vcpu_svm *svm) > h = &svm->nested.hsave->control; > g = &svm->nested; > > + /* No need to intercept #UD if L1 doesn't intercept it */ > + h_intercept_exceptions = > + h->intercept_exceptions & ~(1U << UD_VECTOR); > + > c->intercept_cr = h->intercept_cr | g->intercept_cr; > c->intercept_dr = h->intercept_dr | g->intercept_dr; > - c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions; > + c->intercept_exceptions = > + h_intercept_exceptions | g->intercept_exceptions; > c->intercept = h->intercept | g->intercept; > } > > @@ -2188,6 +2194,7 @@ static int ud_interception(struct vcpu_svm *svm) > { > int er; > > + WARN_ON_ONCE(is_guest_mode(&svm->vcpu)); > er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD); > if (er != EMULATE_DONE) > kvm_queue_exception(&svm->vcpu, UD_VECTOR); > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 95a01609d7ee..dfa856d31b17 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -1878,7 +1878,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > { > u32 eb; > > - eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | > + eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) | > (1u << DB_VECTOR) | (1u << AC_VECTOR); > if ((vcpu->guest_debug & > (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == > @@ -1896,6 +1896,8 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > */ > if (is_guest_mode(vcpu)) > eb |= get_vmcs12(vcpu)->exception_bitmap; > + else > + eb |= 1u << UD_VECTOR; > > vmcs_write32(EXCEPTION_BITMAP, eb); > } > @@ -5881,10 +5883,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) > return 1; /* already handled by vmx_vcpu_run() */ > > if (is_invalid_opcode(intr_info)) { > - if (is_guest_mode(vcpu)) { > - kvm_queue_exception(vcpu, UD_VECTOR); > - return 1; > - } > + WARN_ON_ONCE(is_guest_mode(vcpu)); > er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD); > if (er != EMULATE_DONE) > kvm_queue_exception(vcpu, UD_VECTOR); > Reviewed-by: Paolo Bonzini