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Date: Thu, 31 Jan 2013 10:29:23 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Jan Beulich <JBeulich@suse.com>
CC: KY Srinivasan <kys@microsoft.com>, "olaf@aepfle.de" <olaf@aepfle.de>,
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Subject: Re: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V
References: <1359507077-26050-1-git-send-email-kys@microsoft.com> <1359507108-26091-1-git-send-email-kys@microsoft.com> <1359507108-26091-2-git-send-email-kys@microsoft.com> <5108ED9702000078000BAA08@nat28.tlf.novell.com> <1db4d98aa3434d4eab7b36bbeb89cd47@SN2PR03MB061.namprd03.prod.outlook.com> <510A2D5802000078000BAEAA@nat28.tlf.novell.com> <32e50a43db8849f2944db256989bebb8@SN2PR03MB061.namprd03.prod.outlook.com> <fe91cec766464b4fbfeea56d7e5de0a0@SN2PR03MB061.namprd03.prod.outlook.com> <510AADBE02000078000BB190@nat28.tlf.novell.com>
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On 01/31/2013 08:45 AM, Jan Beulich wrote:
>>>> On 31.01.13 at 16:53, KY Srinivasan <kys@microsoft.com> wrote:
>> Are there any published standards in terms of how the CPUID space should be
>> populated in the range from 0x40000000 to 0x40010000. Specifically, unless
>
> I recall having seen this range being marked as reserved for
> hypervisor use somewhere, but I don't remember where that was.
>

AFAIK Intel reserves 0x40000000 to 0x4FFFFFFF for hypervisor use. 
Typically multivendor CPUID utilities expect "blocks" of 64K but that is 
not in any spec that I know of.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.