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[Qemu-devel] [PATCH 2/2] kvm: Enable CPU SMEP feature


From: Marcelo Tosatti
Subject: [Qemu-devel] [PATCH 2/2] kvm: Enable CPU SMEP feature
Date: Wed, 1 Jun 2011 14:31:32 -0300

From: "Yang, Wei Y" <address@hidden>

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 <address@hidden>
 Singed-off-by: Shan, Haitao <address@hidden>
 Singed-off-by: Li, Xin <address@hidden>

Signed-off-by: Marcelo Tosatti <address@hidden>
---
 target-i386/cpuid.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
index 40a73c7..79e7580 100644
--- 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 */
-- 
1.7.5.2




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