x86, kvm: KVM paravirt kernels don't check for CPUID being unavailable

We set cpuid_level to -1 if there is no CPUID instruction (only
possible on i386).

Signed-off-by: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/20120514174059.30236.1064.stgit@bluebook
Resolves-bug: https://bugzilla.kernel.org/show_bug.cgi?id=12122
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/kvm_para.h

@@ -170,6 +170,9 @@ static inline int kvm_para_available(void)
 	unsigned int eax, ebx, ecx, edx;
 	char signature[13];
 
+	if (boot_cpu_data.cpuid_level < 0)
+		return 0;	/* So we don't blow up on old processors */
+
 	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
 	memcpy(signature + 0, &ebx, 4);
 	memcpy(signature + 4, &ecx, 4);