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

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Message-ID: <20080929205634.GA2907@nb.net.home>
Date:	Mon, 29 Sep 2008 22:56:34 +0200
From:	Karel Zak <kzak@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	akataria@...are.com, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	the arch/x86 maintainers <x86@...nel.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>, avi@...hat.com,
	Rusty Russell <rusty@...tcorp.com.au>,
	Zachary Amsden <zach@...are.com>,
	Dan Hecht <dhecht@...are.com>, Jun.Nakajima@...el.com,
	ksrinivasan@...ell.com, Matthias Koenig <mkoenig@...e.de>
Subject: Re: Use CPUID to communicate with the hypervisor.

On Fri, Sep 26, 2008 at 05:09:00PM -0700, H. Peter Anvin wrote:
> Alok Kataria wrote:
>> +{
>> +	if (cpu_has_hypervisor) {
>> +		unsigned int eax, ebx, ecx, edx;
>> +		char hyper_vendor_id[13];
>> +
>> +		cpuid(HYPERVISOR_INFO_LEAF, &eax, &ebx, &ecx, &edx);
>> +		memcpy(hyper_vendor_id + 0, &ebx, 4);
>> +		memcpy(hyper_vendor_id + 4, &ecx, 4);
>> +		memcpy(hyper_vendor_id + 8, &edx, 4);
>> +		hyper_vendor_id[12] = '\0';
>> +		printk(KERN_INFO "Hypervisor vendor id %s\n", hyper_vendor_id);
>> +	}
>> +}
>> +
>
> This should be broken out into a separate file in cpu/*, because we  
> *will* need to detect hypervisors by other means.

 Yes. It would be nice to have "Hypervisor vendor id" somewhere in
 /sys or /proc. It seems that userspace is already hungry for that
 information:

 http://article.gmane.org/gmane.linux.utilities.util-linux-ng/1788

    Karel

-- 
 Karel Zak  <kzak@...hat.com>
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