4.4-stable review patch. If anyone has any objections, please let me know.
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From: Konrad Rzeszutek Wilk konrad.wilk@oracle.com
commit da39556f66f5cfe8f9c989206974f1cb16ca5d7c upstream.
Expose the CPUID.7.EDX[31] bit to the guest, and also guard against various combinations of SPEC_CTRL MSR values.
The handling of the MSR (to take into account the host value of SPEC_CTRL Bit(2)) is taken care of in patch:
KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest and host IBRS
Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Ingo Molnar mingo@kernel.org
[dwmw2: Handle 4.9 guest CPUID differences, rename guest_cpu_has_ibrs() → guest_cpu_has_spec_ctrl()] Signed-off-by: David Woodhouse dwmw@amazon.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 4.4: Update feature bit name] Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/cpuid.h | 4 ++-- arch/x86/kvm/svm.c | 4 ++-- arch/x86/kvm/vmx.c | 6 +++--- 4 files changed, 8 insertions(+), 8 deletions(-)
--- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -364,7 +364,7 @@ static inline int __do_cpuid_ent(struct
/* cpuid 7.0.edx*/ const u32 kvm_cpuid_7_0_edx_x86_features = - F(SPEC_CTRL) | F(ARCH_CAPABILITIES); + F(SPEC_CTRL) | F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES);
/* all calls to cpuid_count() should be made on the same cpu */ get_cpu(); --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -170,7 +170,7 @@ static inline bool guest_cpuid_has_ibpb( return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL)); }
-static inline bool guest_cpuid_has_ibrs(struct kvm_vcpu *vcpu) +static inline bool guest_cpuid_has_spec_ctrl(struct kvm_vcpu *vcpu) { struct kvm_cpuid_entry2 *best;
@@ -178,7 +178,7 @@ static inline bool guest_cpuid_has_ibrs( if (best && (best->ebx & bit(X86_FEATURE_IBRS))) return true; best = kvm_find_cpuid_entry(vcpu, 7, 0); - return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL)); + return best && (best->edx & (bit(X86_FEATURE_SPEC_CTRL) | bit(X86_FEATURE_SPEC_CTRL_SSBD))); }
static inline bool guest_cpuid_has_arch_capabilities(struct kvm_vcpu *vcpu) --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -3090,7 +3090,7 @@ static int svm_get_msr(struct kvm_vcpu * break; case MSR_IA32_SPEC_CTRL: if (!msr_info->host_initiated && - !guest_cpuid_has_ibrs(vcpu)) + !guest_cpuid_has_spec_ctrl(vcpu)) return 1;
msr_info->data = svm->spec_ctrl; @@ -3171,7 +3171,7 @@ static int svm_set_msr(struct kvm_vcpu * break; case MSR_IA32_SPEC_CTRL: if (!msr->host_initiated && - !guest_cpuid_has_ibrs(vcpu)) + !guest_cpuid_has_spec_ctrl(vcpu)) return 1;
/* The STIBP bit doesn't fault even if it's not advertised */ --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2861,7 +2861,7 @@ static int vmx_get_msr(struct kvm_vcpu * break; case MSR_IA32_SPEC_CTRL: if (!msr_info->host_initiated && - !guest_cpuid_has_ibrs(vcpu)) + !guest_cpuid_has_spec_ctrl(vcpu)) return 1;
msr_info->data = to_vmx(vcpu)->spec_ctrl; @@ -2973,11 +2973,11 @@ static int vmx_set_msr(struct kvm_vcpu * break; case MSR_IA32_SPEC_CTRL: if (!msr_info->host_initiated && - !guest_cpuid_has_ibrs(vcpu)) + !guest_cpuid_has_spec_ctrl(vcpu)) return 1;
/* The STIBP bit doesn't fault even if it's not advertised */ - if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP)) + if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD)) return 1;
vmx->spec_ctrl = data;