From mboxrd@z Thu Jan 1 00:00:00 1970 From: KarimAllah Ahmed Subject: [RFC 02/10] x86/kvm: Add IBPB support Date: Sat, 20 Jan 2018 20:22:53 +0100 Message-ID: <1516476182-5153-3-git-send-email-karahmed@amazon.de> References: <1516476182-5153-1-git-send-email-karahmed@amazon.de> Cc: KarimAllah Ahmed , Andi Kleen , Andrea Arcangeli , Andy Lutomirski , Arjan van de Ven , Ashok Raj , Asit Mallick , Borislav Petkov , Dan Williams , Dave Hansen , David Woodhouse , Greg Kroah-Hartman , "H . Peter Anvin" , Ingo Molnar , Janakarajan Natarajan , Joerg Roedel , Jun Nakajima , Laura Abbott , Linus Torvalds , Masami Hiramatsu Received: from smtp-fw-9101.amazon.com ([207.171.184.25]:16292 "EHLO smtp-fw-9101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756642AbeATT2M (ORCPT ); Sat, 20 Jan 2018 14:28:12 -0500 In-Reply-To: <1516476182-5153-1-git-send-email-karahmed@amazon.de> Sender: kvm-owner@vger.kernel.org List-ID: From: Ashok Raj Add MSR passthrough for MSR_IA32_PRED_CMD and place branch predictor barriers on switching between VMs to avoid inter VM specte-v2 attacks. [peterz: rebase and changelog rewrite] [dwmw2: fixes] [karahmed: - vmx: expose PRED_CMD whenever it is available - svm: only pass through IBPB if it is available] Cc: Asit Mallick Cc: Dave Hansen Cc: Arjan Van De Ven Cc: Tim Chen Cc: Linus Torvalds Cc: Andrea Arcangeli Cc: Andi Kleen Cc: Thomas Gleixner Cc: Dan Williams Cc: Jun Nakajima Cc: Andy Lutomirski Cc: Greg KH Cc: David Woodhouse Cc: Paolo Bonzini Signed-off-by: Ashok Raj Signed-off-by: Peter Zijlstra (Intel) Link: http://lkml.kernel.org/r/1515720739-43819-6-git-send-email-ashok.raj@intel.com Signed-off-by: David Woodhouse Signed-off-by: KarimAllah Ahmed --- arch/x86/kvm/svm.c | 14 ++++++++++++++ arch/x86/kvm/vmx.c | 4 ++++ 2 files changed, 18 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 2744b973..cfdb9ab 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -529,6 +529,7 @@ struct svm_cpu_data { struct kvm_ldttss_desc *tss_desc; struct page *save_area; + struct vmcb *current_vmcb; }; static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data); @@ -918,6 +919,9 @@ static void svm_vcpu_init_msrpm(u32 *msrpm) set_msr_interception(msrpm, direct_access_msrs[i].index, 1, 1); } + + if (boot_cpu_has(X86_FEATURE_AMD_PRED_CMD)) + set_msr_interception(msrpm, MSR_IA32_PRED_CMD, 1, 1); } static void add_msr_offset(u32 offset) @@ -1706,11 +1710,17 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu) __free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER); kvm_vcpu_uninit(vcpu); kmem_cache_free(kvm_vcpu_cache, svm); + /* + * The vmcb page can be recycled, causing a false negative in + * svm_vcpu_load(). So do a full IBPB now. + */ + indirect_branch_prediction_barrier(); } static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { struct vcpu_svm *svm = to_svm(vcpu); + struct svm_cpu_data *sd = per_cpu(svm_data, cpu); int i; if (unlikely(cpu != vcpu->cpu)) { @@ -1739,6 +1749,10 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) if (static_cpu_has(X86_FEATURE_RDTSCP)) wrmsrl(MSR_TSC_AUX, svm->tsc_aux); + if (sd->current_vmcb != svm->vmcb) { + sd->current_vmcb = svm->vmcb; + indirect_branch_prediction_barrier(); + } avic_vcpu_load(vcpu, cpu); } diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index d1e25db..3b64de2 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2279,6 +2279,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) if (per_cpu(current_vmcs, cpu) != vmx->loaded_vmcs->vmcs) { per_cpu(current_vmcs, cpu) = vmx->loaded_vmcs->vmcs; vmcs_load(vmx->loaded_vmcs->vmcs); + indirect_branch_prediction_barrier(); } if (!already_loaded) { @@ -6791,6 +6792,9 @@ static __init int hardware_setup(void) kvm_tsc_scaling_ratio_frac_bits = 48; } + if (boot_cpu_has(X86_FEATURE_SPEC_CTRL)) + vmx_disable_intercept_for_msr(MSR_IA32_PRED_CMD, false); + vmx_disable_intercept_for_msr(MSR_FS_BASE, false); vmx_disable_intercept_for_msr(MSR_GS_BASE, false); vmx_disable_intercept_for_msr(MSR_KERNEL_GS_BASE, true); -- 2.7.4