From 9f578c4dbb6cdf3cc7162b474086bc13c580f7df Mon Sep 17 00:00:00 2001 From: KarimAllah Ahmed Date: Thu, 1 Feb 2018 22:59:44 +0100 Subject: [PATCH 45/48] KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES CVE-2017-5715 (Spectre v2 IPBP) commit 28c1c9fabf48d6ad596273a11c46e0d0da3e14cd Intel processors use MSR_IA32_ARCH_CAPABILITIES MSR to indicate RDCL_NO (bit 0) and IBRS_ALL (bit 1). This is a read-only MSR. By default the contents will come directly from the hardware, but user-space can still override it. [dwmw2: The bit in kvm_cpuid_7_0_edx_x86_features can be unconditional] Signed-off-by: KarimAllah Ahmed Signed-off-by: David Woodhouse Signed-off-by: Thomas Gleixner Reviewed-by: Paolo Bonzini Reviewed-by: Darren Kenny Reviewed-by: Jim Mattson Reviewed-by: Konrad Rzeszutek Wilk Cc: Andrea Arcangeli Cc: Andi Kleen Cc: Jun Nakajima Cc: kvm@vger.kernel.org Cc: Dave Hansen Cc: Linus Torvalds Cc: Andy Lutomirski Cc: Asit Mallick Cc: Arjan Van De Ven Cc: Greg KH Cc: Dan Williams Cc: Tim Chen Cc: Ashok Raj Link: https://lkml.kernel.org/r/1517522386-18410-4-git-send-email-karahmed@amazon.de Signed-off-by: Greg Kroah-Hartman (backported from commit 8ed57aa36d18782d0e587f664d4529d29d36918f) Signed-off-by: Andy Whitcroft --- arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/vmx.c | 15 +++++++++++++++ arch/x86/kvm/x86.c | 1 + 3 files changed, 17 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 0d42e6cced23..bc7fb41bd491 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -391,7 +391,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, /* cpuid 7.0.edx*/ const u32 kvm_cpuid_7_0_edx_x86_features = - KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS); + KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS) | KF(ARCH_CAPABILITIES); /* all calls to cpuid_count() should be made on the same cpu */ get_cpu(); diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index c175ee78ee93..66b87b55c9aa 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -579,6 +579,8 @@ struct vcpu_vmx { u64 msr_guest_kernel_gs_base; #endif + u64 arch_capabilities; + u32 vm_entry_controls_shadow; u32 vm_exit_controls_shadow; /* @@ -3228,6 +3230,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_IA32_TSC: msr_info->data = guest_read_tsc(vcpu); break; + case MSR_IA32_ARCH_CAPABILITIES: + if (!msr_info->host_initiated && + !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES)) + return 1; + msr_info->data = to_vmx(vcpu)->arch_capabilities; + break; case MSR_IA32_SYSENTER_CS: msr_info->data = vmcs_read32(GUEST_SYSENTER_CS); break; @@ -3363,6 +3371,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vmx_disable_intercept_for_msr(vmx->vmcs01.msr_bitmap, MSR_IA32_PRED_CMD, MSR_TYPE_W); break; + case MSR_IA32_ARCH_CAPABILITIES: + if (!msr_info->host_initiated) + return 1; + vmx->arch_capabilities = data; + break; case MSR_IA32_CR_PAT: if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) { if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data)) @@ -5511,6 +5524,8 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) ++vmx->nmsrs; } + if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES)) + rdmsrl(MSR_IA32_ARCH_CAPABILITIES, vmx->arch_capabilities); vm_exit_controls_init(vmx, vmcs_config.vmexit_ctrl); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b4858cdc000d..ccb926a2cd4d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -984,6 +984,7 @@ static u32 msrs_to_save[] = { #endif MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_TSC_AUX, + MSR_IA32_ARCH_CAPABILITIES }; static unsigned num_msrs_to_save; -- 2.15.1