Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751293AbeAPAz6 (ORCPT + 1 other); Mon, 15 Jan 2018 19:55:58 -0500 Received: from mx.ewheeler.net ([66.155.3.69]:56442 "EHLO mail.ewheeler.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751210AbeAPAz5 (ORCPT ); Mon, 15 Jan 2018 19:55:57 -0500 Date: Tue, 16 Jan 2018 00:55:56 +0000 (UTC) From: Eric Wheeler X-X-Sender: lists@mail.ewheeler.net To: Paolo Bonzini cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rkrcmar@redhat.com, liran.alon@oracle.com, jmattson@google.com, aliguori@amazon.com, thomas.lendacky@amd.com, dwmw@amazon.co.uk, bp@alien8.de, x86@kernel.org Subject: Re: [PATCH 9/8] KVM: x86: limit MSR_IA32_SPEC_CTRL access based on CPUID availability In-Reply-To: <20180109120311.27565-10-pbonzini@redhat.com> Message-ID: References: <20180109120311.27565-1-pbonzini@redhat.com> <20180109120311.27565-10-pbonzini@redhat.com> User-Agent: Alpine 2.11 (LRH 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Tue, 9 Jan 2018, Paolo Bonzini wrote: > MSR_IA32_SPEC_CTRL is not available unless CPU[7,0].EDX[26] is 1. > Check that against host CPUID or guest CPUID, respectively for > host-initiated and guest-initiated accesses. Hi Radim, Paolo: In porting this patch series to v4.14, I'm getting this BUILD_BUG_ON: In file included from arch/x86/kvm/vmx.c:21:0: In function 'x86_feature_cpuid', inlined from 'guest_cpuid_get_register' at arch/x86/kvm/cpuid.h:72:25, inlined from 'vmx_get_msr' at arch/x86/kvm/cpuid.h:101:6: arch/x86/kvm/cpuid.h:64:232: error: call to '__compiletime_assert_64' declared with attribute error: BUILD_BUG_ON failed: reverse_cpuid[x86_leaf].function == 0 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); ^ In function 'x86_feature_cpuid', inlined from 'guest_cpuid_get_register' at arch/x86/kvm/cpuid.h:72:25, inlined from 'vmx_set_msr' at arch/x86/kvm/cpuid.h:101:6: arch/x86/kvm/cpuid.h:64:232: error: call to '__compiletime_assert_64' declared with attribute error: BUILD_BUG_ON failed: reverse_cpuid[x86_leaf].function == 0 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); I think this is caused by the following call stack for X86_FEATURE_SPEC_CTRL, but if not please correct me here: arch/x86/kvm/vmx.c: vmx_get_msr/vmx_set_msr() guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) guest_cpuid_get_register(vcpu, x86_feature); x86_feature_cpuid(x86_feature); x86_feature_cpuid(unsigned x86_feature) BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); It looks like I need to add something to reverse_cpuid[] but I'm not sure what. Do you know what needs to be added here? -Eric -- Eric Wheeler > > Suggested-by: Jim Mattson > Signed-off-by: Paolo Bonzini > --- > This is for after X86_FEATURE_SPEC_CTRL is added to Linux, but > I still wanted to ack Jim's improvement. > > arch/x86/kvm/svm.c | 8 ++++++++ > arch/x86/kvm/vmx.c | 8 ++++++++ > 2 files changed, 16 insertions(+) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 97126c2bd663..3a646580d7c5 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -3648,6 +3648,10 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > msr_info->data = svm->nested.vm_cr_msr; > break; > case MSR_IA32_SPEC_CTRL: > + if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) || > + (!msr_info->host_initiated && > + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))) > + return 1; > msr_info->data = svm->spec_ctrl; > break; > case MSR_IA32_UCODE_REV: > @@ -3806,6 +3810,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) > vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, data); > break; > case MSR_IA32_SPEC_CTRL: > + if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) || > + (!msr_info->host_initiated && > + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))) > + return 1; > svm->spec_ctrl = data; > break; > case MSR_IA32_APICBASE: > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 49b4a2d61603..42bc7ee293e4 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3368,6 +3368,10 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > msr_info->data = guest_read_tsc(vcpu); > break; > case MSR_IA32_SPEC_CTRL: > + if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) || > + (!msr_info->host_initiated && > + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))) > + return 1; > msr_info->data = to_vmx(vcpu)->spec_ctrl; > break; > case MSR_IA32_SYSENTER_CS: > @@ -3510,6 +3514,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > kvm_write_tsc(vcpu, msr_info); > break; > case MSR_IA32_SPEC_CTRL: > + if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) || > + (!msr_info->host_initiated && > + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))) > + return 1; > to_vmx(vcpu)->spec_ctrl = data; > break; > case MSR_IA32_CR_PAT: > -- > 1.8.3.1 > >