x86, kvm: Switch to use hypervisor_cpuid_base()

Switch to use hypervisor_cpuid_base() to detect KVM.

Cc: Gleb Natapov <[e-mail]>
Cc: Paolo Bonzini <[e-mail]>
Signed-off-by: Jason Wang <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/include/asm/kvm_para.h

···
 	return ret;
 }
 
+static inline uint32_t kvm_cpuid_base(void)
+{
+	if (boot_cpu_data.cpuid_level < 0)
+		return 0;	/* So we don't blow up on old processors */
+
+	if (cpu_has_hypervisor)
+		return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
+
+	return 0;
+}
+
 static inline bool kvm_para_available(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 */
-
-	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 true;
-	}
-
-	return false;
+	return kvm_cpuid_base() != 0;
 }
 
 static inline unsigned int kvm_arch_para_features(void)