[PATCH] x86/kvm/svm: Simplify cpu_has_svm()

From: Borislav Petkov
Date: Mon May 09 2016 - 05:53:14 EST


From: Borislav Petkov <bp@xxxxxxx>

Use already cached CPUID information instead of querying CPUID again.

No functionality change.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
---
arch/x86/include/asm/svm.h | 1 -
arch/x86/include/asm/virtext.h | 8 ++------
2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 6136d99f537b..41888f51f936 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -185,7 +185,6 @@ struct __attribute__ ((__packed__)) vmcb {
struct vmcb_save_area save;
};

-#define SVM_CPUID_FEATURE_SHIFT 2
#define SVM_CPUID_FUNC 0x8000000a

#define SVM_VM_CR_SVM_DISABLE 4
diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index cce9ee68e335..0116b2ee9e64 100644
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -83,23 +83,19 @@ static inline void cpu_emergency_vmxoff(void)
*/
static inline int cpu_has_svm(const char **msg)
{
- uint32_t eax, ebx, ecx, edx;
-
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
if (msg)
*msg = "not amd";
return 0;
}

- cpuid(0x80000000, &eax, &ebx, &ecx, &edx);
- if (eax < SVM_CPUID_FUNC) {
+ if (boot_cpu_data.extended_cpuid_level < SVM_CPUID_FUNC) {
if (msg)
*msg = "can't execute cpuid_8000000a";
return 0;
}

- cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
- if (!(ecx & (1 << SVM_CPUID_FEATURE_SHIFT))) {
+ if (!boot_cpu_has(X86_FEATURE_SVM)) {
if (msg)
*msg = "svm not available";
return 0;
--
2.7.3