Messages in this thread Patch in this message | | | Subject | Re: [9/8] KVM: x86: limit MSR_IA32_SPEC_CTRL access based on CPUID availability | From | Mihai Carabas <> | Date | Tue, 30 Jan 2018 15:21:11 +0200 |
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Hello Paolo,
I've back ported this patch on 4.1, after adding the per-vcpu MSR bitmap. Also enabled the SPEC_CTRL_MSR intercept if qemu instructed so [1].
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
[1] +++ b/arch/x86/kvm/vmx.c @@ -8391,6 +8391,16 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PRED_CMD, MSR_TYPE_R | MSR_TYPE_W); vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_BNDCFGS, MSR_TYPE_R | MSR_TYPE_W);
+ /* + * If the physical CPU or the vCPU of this VM doesn't + * support SPEC_CTRL feature, catch each access to it. + */ + if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) || + !guest_cpuid_has_spec_ctrl(&vmx->vcpu)) + vmx_enable_intercept_for_msr( + msr_bitmap, + MSR_IA32_SPEC_CTRL, + MSR_TYPE_R | MSR_TYPE_W);
/* * If PML is turned on, failure on enabling PML just results in failure
On 09.01.2018 14:03, 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. > > Suggested-by: Jim Mattson <jmattson@google.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > 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: >
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