linux-kernel - Re: [PATCH 2/4] Hypervisor detection and get tsc

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Date:	Mon, 10 Nov 2008 07:32:06 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Mark McLoughlin <markmc@...hat.com>
CC:	akataria@...are.com, Ingo Molnar <mingo@...e.hu>,
	Andi Kleen <andi@...stfloor.org>,
	LKML <linux-kernel@...r.kernel.org>,
	the arch/x86 maintainers <x86@...nel.org>,
	Daniel Hecht <dhecht@...are.com>
Subject: Re: [PATCH 2/4] Hypervisor detection and get tsc_freq from	hypervisor

Mark McLoughlin wrote:
>>
>> diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
>> index f73e95d..78478f2 100644
>> --- a/arch/x86/include/asm/cpufeature.h
>> +++ b/arch/x86/include/asm/cpufeature.h
>> @@ -117,6 +117,7 @@
>>  #define X86_FEATURE_XSAVE	(4*32+26) /* XSAVE/XRSTOR/XSETBV/XGETBV */
>>  #define X86_FEATURE_OSXSAVE	(4*32+27) /* "" XSAVE enabled in the OS */
>>  #define X86_FEATURE_AVX		(4*32+28) /* Advanced Vector Extensions */
>> +#define X86_FEATURE_HYPERVISOR	(4*32+31) /* Running on a hypervisor */
> 
> I don't see you set this anywhere.
> 

This bit is set by the hypervisor in the pattern returned by the CPUID
instruction.

	-hpa
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