Re: [PATCH] x86: properly handle KVM emulation of hyperv

["H. Peter Anvin" <hpa@zytor.com>]

On 07/19/2013 05:10 AM, Paolo Bonzini wrote:
>> +
>> +static inline bool kvm_para_available(void)
>> +{
>>  	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)
>> +		if (kvm_para_available_function(KVM_CPUID_SIGNATURE) ||
>> +		    kvm_para_available_function(KVM_CPUID_SIGNATURE_NEXT))
>>  			return true;
>>  	}
> 
> Nice catch.  Just one small thing, you should loop until 0x40010000, as
> done in arch/x86/include/asm/xen/hypervisor.h, in case one day a third
> hypervisor implements three extensions (Hyper-V, KVM and its own set).
> 

Any way we can centralize this stuff?

	-hpa