linux-kernel - [PATCH] x86/kvm/svm: Simplify cpu_has

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Message-Id: <1462787586-24151-1-git-send-email-bp@alien8.de>
Date:	Mon,  9 May 2016 11:53:06 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org, x86@...nel.org
Subject: [PATCH] x86/kvm/svm: Simplify cpu_has_svm()

From: Borislav Petkov <bp@...e.de>

Use already cached CPUID information instead of querying CPUID again.

No functionality change.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Joerg Roedel <joro@...tes.org>
Cc: kvm@...r.kernel.org
Cc: x86@...nel.org
---
 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