linux-kernel - Re: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V

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Message-ID: <510AB803.2010004@zytor.com>
Date:	Thu, 31 Jan 2013 10:29:23 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jan Beulich <JBeulich@...e.com>
CC:	KY Srinivasan <kys@...rosoft.com>,
	"olaf@...fle.de" <olaf@...fle.de>, "bp@...en8.de" <bp@...en8.de>,
	"apw@...onical.com" <apw@...onical.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"jasowang@...hat.com" <jasowang@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V

On 01/31/2013 08:45 AM, Jan Beulich wrote:
>>>> On 31.01.13 at 16:53, KY Srinivasan <kys@...rosoft.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.

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