linux-kernel - Re: Use CPUID to communicate with the hypervisor.

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Message-ID: <20080929092855.GK3776@york.uk.xensource.com>
Date:	Mon, 29 Sep 2008 10:28:55 +0100
From:	Tim Deegan <Tim.Deegan@...rix.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	akataria@...are.com, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	the arch/x86 maintainers <x86@...nel.org>,
	"avi@...hat.com" <avi@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Zach Amsden <zach@...are.com>,
	Daniel Hecht <dhecht@...are.com>,
	"Jun.Nakajima@...el.Com" <Jun.Nakajima@...el.Com>
Subject: Re: Use CPUID to communicate with the hypervisor.

At 22:01 -0700 on 27 Sep (1222552861), Jeremy Fitzhardinge wrote:
> Alok Kataria wrote:
>>> I think there's a move towards doing a scan for a signature, such as
>>> checking every 16 leaves after 0x40000000 for "a while" looking for
>>> interesting signatures, so that a hypervisor can support multiple ABIs
>>> at once.  Given this, it would be better to define a "Generic Hypervisor
>>> ABI" signature, and put all the related leaves together.
>>
>> Hmm interesting, do you have any pointers to this ?
>
> No.  I think I saw a passing reference from Tim Deegan to it, but I
> couldn't find it again when I looked.

I was talking about checking every 256 leaves from 0x40000000, but I
can't remember where I heard it.  The only relevant reference I can
find is the MS hypervisor interface spec's description of leaf
0x40000001: "Hypervisor vendor-neutral interface identification.  This
determines the semantics of the leaves from 0x40000002 through
0x400000FF"

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@...rix.com>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]
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