3.16.49-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Jim Mattson <[email protected]> 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 <[email protected]> Signed-off-by: Radim Krčmář <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- arch/x86/kvm/cpuid.h | 8 ++++++++ arch/x86/kvm/vmx.c | 4 ++-- 2 files changed, 10 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -95,4 +95,13 @@ static inline bool guest_cpuid_has_gbpag best = kvm_find_cpuid_entry(vcpu, 0x80000001, 0); return best && (best->edx & bit(X86_FEATURE_GBPAGES)); } + +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)); +} + #endif --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2514,7 +2514,7 @@ static int vmx_get_msr(struct kvm_vcpu * data = vmcs_readl(GUEST_SYSENTER_ESP); break; case MSR_IA32_BNDCFGS: - if (!vmx_mpx_supported()) + if (!vmx_mpx_supported() || !guest_cpuid_has_mpx(vcpu)) return 1; data = vmcs_read64(GUEST_BNDCFGS); break; @@ -2587,7 +2587,7 @@ static int vmx_set_msr(struct kvm_vcpu * vmcs_writel(GUEST_SYSENTER_ESP, data); break; case MSR_IA32_BNDCFGS: - if (!vmx_mpx_supported()) + if (!vmx_mpx_supported() || !guest_cpuid_has_mpx(vcpu)) return 1; vmcs_write64(GUEST_BNDCFGS, data); break;
