[PATCH] kvm_para_available() should check hypervisor bit before accessing hypervisor cpuid leaf.

[Gleb Natapov <gleb@xxxxxxxxxx>]

This couid range does not exist on real HW and Intel spec says that
"Information returned for highest basic information leaf" will be
returned. Not very well defined. 

Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 99c4bbe..a7a7a94 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -178,14 +178,16 @@ static inline int kvm_para_available(void)
 	unsigned int eax, ebx, ecx, edx;
 	char signature[13];
 
-	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 (strcmp(signature, "KVMKVMKVM") == 0)
-		return 1;
+	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 (strcmp(signature, "KVMKVMKVM") == 0)
+			return 1;
+	}
 
 	return 0;
 }
--
			Gleb.
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