From: Alan Cox <alan@linux.intel.com>
Date: Mon, 14 May 2012 17:41:09 +0000 (+0100)
Subject: x86, kvm: KVM paravirt kernels don't check for CPUID being unavailable
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c3709e6734daa4d9b37fe31592ebb0eb57bae1bb;p=linux-beck.git

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>
---

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 734c3767cfac..183922e13de1 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/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);