From a40f0ccd4f1c2751d5df5d9a63b9cf93ff70d343 Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Wed, 24 May 2017 10:49:25 -0700 Subject: [PATCH] kvm: x86: Guest BNDCFGS requires guest MPX support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 4439af9f911ae0243ffe4e2dfc12bace49605d8b upstream. The BNDCFGS MSR should only be exposed to the guest if the guest supports MPX. (cf. the TSC_AUX MSR and RDTSCP.) Fixes: 0dd376e709975779 ("KVM: x86: add MSR_IA32_BNDCFGS to msrs_to_save") Change-Id: I3ad7c01bda616715137ceac878f3fa7e66b6b387 Signed-off-by: Jim Mattson Signed-off-by: Radim Krčmář Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/cpuid.h | 8 ++++++++ arch/x86/kvm/vmx.c | 4 ++-- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 33d574fb2445b..d1534feefcfeb 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -143,6 +143,14 @@ static inline bool guest_cpuid_has_pcommit(struct kvm_vcpu *vcpu) return best && (best->ebx & bit(X86_FEATURE_PCOMMIT)); } +static inline bool guest_cpuid_has_mpx(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 7, 0); + return best && (best->ebx & bit(X86_FEATURE_MPX)); +} + static inline bool guest_cpuid_has_rdtscp(struct kvm_vcpu *vcpu) { struct kvm_cpuid_entry2 *best; diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 0e0c52e57e900..3d776b6257668 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2812,7 +2812,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = vmcs_readl(GUEST_SYSENTER_ESP); break; case MSR_IA32_BNDCFGS: - if (!kvm_mpx_supported()) + if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu)) return 1; msr_info->data = vmcs_read64(GUEST_BNDCFGS); break; @@ -2889,7 +2889,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vmcs_writel(GUEST_SYSENTER_ESP, data); break; case MSR_IA32_BNDCFGS: - if (!kvm_mpx_supported()) + if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu)) return 1; vmcs_write64(GUEST_BNDCFGS, data); break;