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 734c3767cfac96075b52a39a641d4430a4fb4102..183922e13de1aa83ead2959144378e96934d4608 100644 (file)
--- 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);