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

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Message-ID: <51E9A9BA.1070805@zytor.com>
Date:	Fri, 19 Jul 2013 14:03:54 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	Jason Wang <jasowang@...hat.com>, gleb@...hat.com,
	tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Vadim Rozenfeld <vrozenfe@...hat.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>
Subject: Re: [PATCH] x86: properly handle KVM emulation of hyperv

On 07/19/2013 02:00 PM, Paolo Bonzini wrote:
> Il 19/07/2013 22:59, H. Peter Anvin ha scritto:
>>>>>> -		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?
> 
> I guess a function cpuid_hypervisor_base("KVMKVMKVM") that does the scan?
> 

Something like that.

	-hpa


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