KVM: Add SMAP support when setting CR4

This patch adds SMAP handling logic when setting CR4 for guests

Thanks a lot to Paolo Bonzini for his suggestion to use the branchless
way to detect SMAP violation.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index a2a1bb7ed8c1..eeecbed26ac7 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -48,6 +48,14 @@ static inline bool guest_cpuid_has_smep(struct kvm_vcpu *vcpu)
         return best && (best->ebx & bit(X86_FEATURE_SMEP));
 }
 
+static inline bool guest_cpuid_has_smap(struct kvm_vcpu *vcpu)
+{
+        struct kvm_cpuid_entry2 *best;
+
+        best = kvm_find_cpuid_entry(vcpu, 7, 0);
+        return best && (best->ebx & bit(X86_FEATURE_SMAP));
+}
+
 static inline bool guest_cpuid_has_fsgsbase(struct kvm_vcpu *vcpu)
 {
         struct kvm_cpuid_entry2 *best;