Re: Use CPUID to communicate with the hypervisor.

From: Karel Zak <kzak@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: akataria@vmware.com, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	avi@redhat.com, Rusty Russell <rusty@rustcorp.com.au>,
	Zachary Amsden <zach@vmware.com>, Dan Hecht <dhecht@vmware.com>,
	Jun.Nakajima@intel.com, ksrinivasan@novell.com,
	Matthias Koenig <mkoenig@suse.de>
Subject: Re: Use CPUID to communicate with the hypervisor.
Date: Mon, 29 Sep 2008 22:56:34 +0200	[thread overview]
Message-ID: <20080929205634.GA2907@nb.net.home> (raw)
In-Reply-To: <48DD799C.3070706@zytor.com>

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@redhat.com>