kvm: Enable CPU SMEP feature

This patchset enables a new CPU feature SMEP (Supervisor Mode Execution
Protection) in QEMU-KVM. SMEP prevents kernel from executing code in application.
Updated Intel SDM describes this CPU feature. The document will be published soon.

SMEP is identified by CPUID leaf 7 EBX[7], which is 0 before. Get the right value by query KVM kernel module, so that guest can get SMEP through CPUID.

 Signed-off-by: Yang, Wei <wei.y.yang@intel.com>
 Singed-off-by: Shan, Haitao <haitao.shan@intel.com>
 Singed-off-by: Li, Xin <xin.li@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
index 40a73c7d117a9657cdf06ac0101834029791b902..79e7580c1768e7f4028c0ccaaeca27e37ddedf05 100644 (file)
--- a/target-i386/cpuid.c
+++ b/target-i386/cpuid.c
@@ -1142,6 +1142,19 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         *ecx = 0;
         *edx = 0;
         break;
+    case 7:
+        if (kvm_enabled()) {
+            *eax = kvm_arch_get_supported_cpuid(env, 0x7, count, R_EAX);
+            *ebx = kvm_arch_get_supported_cpuid(env, 0x7, count, R_EBX);
+            *ecx = kvm_arch_get_supported_cpuid(env, 0x7, count, R_ECX);
+            *edx = kvm_arch_get_supported_cpuid(env, 0x7, count, R_EDX);
+        } else {
+            *eax = 0;
+            *ebx = 0;
+            *ecx = 0;
+            *edx = 0;
+        }
+        break;
     case 9:
         /* Direct Cache Access Information Leaf */
         *eax = 0; /* Bits 0-31 in DCA_CAP MSR */