linux-kernel - Re: [PATCH 1/2] VMware detection support for x86 and x86-64

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Date:	Wed, 24 Sep 2008 21:46:18 -0700
From:	Alok Kataria <akataria@...are.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Alok kataria <alokkataria1@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Yan Li <elliot.li.tech@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"joerg.roedel@....com" <joerg.roedel@....com>,
	"rjmaomao@...il.com" <rjmaomao@...il.com>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Daniel Hecht <dhecht@...are.com>, Zach Amsden <zach@...are.com>
Subject: Re: [PATCH 1/2] VMware detection support for x86 and x86-64

On Wed, 2008-09-24 at 21:38 -0700, H. Peter Anvin wrote:
> Alok kataria wrote:
> >
> > Even if there is anything on that port on native hardware it would
> > work perfectly well and is _safe_.
> > First let me post the code to access this backdoor port (the way it
> > should really be done )
> >
> > So whenever we query port  0x5658 , with the GETVERSION command (which
> > is the first thing we do with this port), we expect that  eax !=
> > 0xFFFFFFFF   and ebx has a  VMWARE specific MAGIC value.  Please note
> > that ebx has been initialized to zero in the code above.
> >
> 
> You have no idea what you just did to a real piece of hardware.
Why ? what do you mean ? 
ebx is a local variable in the code above that i posted. 
Only when on hypervisor will we write the magic value over there.
How can this affect native hardware, i fail to understand. 
Please explain.

Thanks,
Alok
> 
>         -hpa

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