[PATCH v4] Enable CPU SMEP feature support for QEMU-KVM

[PATCH v4] Enable CPU SMEP feature support for QEMU-KVM

[Yang, Wei Y]

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.

Changes since v3: no changes.
Changes since v2: no changes.

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

---
 target-i386/cpuid.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
index 091d812..cd20dbf 100644
--- a/target-i386/cpuid.c
+++ b/target-i386/cpuid.c
@@ -1115,6 +1115,14 @@ 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);
+        }
+        break;
     case 9:
         /* Direct Cache Access Information Leaf */
         *eax = 0; /* Bits 0-31 in DCA_CAP MSR */
-- 
1.7.4.1