KVM: Add SMEP support when setting CR4

This patch adds SMEP handling when setting CR4.

Signed-off-by: Yang, Wei <wei.y.yang@intel.com>
Signed-off-by: Shan, Haitao <haitao.shan@intel.com>
Signed-off-by: Li, Xin <xin.li@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 694538a..ba5cd27 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -580,6 +580,14 @@
 	return best && (best->ecx & bit(X86_FEATURE_XSAVE));
 }
 
+static bool guest_cpuid_has_smep(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpuid_entry2 *best;
+
+	best = kvm_find_cpuid_entry(vcpu, 7, 0);
+	return best && (best->ebx & bit(X86_FEATURE_SMEP));
+}
+
 static void update_cpuid(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpuid_entry2 *best;
@@ -599,14 +607,17 @@
 int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {
 	unsigned long old_cr4 = kvm_read_cr4(vcpu);
-	unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE;
-
+	unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE |
+				   X86_CR4_PAE | X86_CR4_SMEP;
 	if (cr4 & CR4_RESERVED_BITS)
 		return 1;
 
 	if (!guest_cpuid_has_xsave(vcpu) && (cr4 & X86_CR4_OSXSAVE))
 		return 1;
 
+	if (!guest_cpuid_has_smep(vcpu) && (cr4 & X86_CR4_SMEP))
+		return 1;
+
 	if (is_long_mode(vcpu)) {
 		if (!(cr4 & X86_CR4_PAE))
 			return 1;