linux-kernel - [PATCH V2 3/4] kvm: switch to use hypervisor_cpuid

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Date:	Thu, 25 Jul 2013 16:54:34 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, linux-kernel@...r.kernel.org, pbonzini@...hat.com
Cc:	kvm@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
	Gleb Natapov <gleb@...hat.com>
Subject: [PATCH V2 3/4] kvm: switch to use hypervisor_cpuid_base()

Switch to use hypervisor_cpuid_base() to detect KVM.

Cc: Gleb Natapov <gleb@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: kvm@...r.kernel.org
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
Changes from V1:
- Introduce kvm_cpuid_base() which will be used by next patch.
---
 arch/x86/include/asm/kvm_para.h |   24 +++++++++---------------
 1 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 695399f..0644129 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -85,26 +85,20 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
 	return ret;
 }
 
-static inline bool kvm_para_available(void)
+static inline uint32_t kvm_cpuid_base(void)
 {
-	unsigned int eax, ebx, ecx, edx;
-	char signature[13];
-
 	if (boot_cpu_data.cpuid_level < 0)
-		return false;	/* So we don't blow up on old processors */
+		return 0;	/* So we don't blow up on old processors */
 
-	if (cpu_has_hypervisor) {
-		cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
-		memcpy(signature + 0, &ebx, 4);
-		memcpy(signature + 4, &ecx, 4);
-		memcpy(signature + 8, &edx, 4);
-		signature[12] = 0;
+	if (cpu_has_hypervisor)
+		return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
 
-		if (strcmp(signature, "KVMKVMKVM") == 0)
-			return true;
-	}
+	return 0;
+}
 
-	return false;
+static inline bool kvm_para_available(void)
+{
+	return kvm_cpuid_base() != 0;
 }
 
 static inline unsigned int kvm_arch_para_features(void)
-- 
1.7.1

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