From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=54646 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PAVqT-00020a-SG for qemu-devel@nongnu.org; Mon, 25 Oct 2010 18:48:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PAVqS-0007Dg-69 for qemu-devel@nongnu.org; Mon, 25 Oct 2010 18:48:49 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:46818 helo=mail.gmx.net) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1PAVqR-0007DB-Ns for qemu-devel@nongnu.org; Mon, 25 Oct 2010 18:48:48 -0400 From: xscript@gmx.net (=?utf-8?Q?Llu=C3=ADs?=) Subject: Re: [Qemu-devel] Re: backdoor References: <87vd4q5yqd.fsf_-_@ginnungagap.bsc.es> <4CC5783C.8060009@redhat.com> <87pquy4cn7.fsf@ginnungagap.bsc.es> <4CC5F4AE.6020306@codemonkey.ws> Date: Tue, 26 Oct 2010 00:48:37 +0200 In-Reply-To: <4CC5F4AE.6020306@codemonkey.ws> (Anthony Liguori's message of "Mon, 25 Oct 2010 16:20:46 -0500") Message-ID: <87iq0prire.fsf@fulla.xlab.taz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Paolo Bonzini , qemu-devel@nongnu.org Anthony Liguori writes: > On 10/25/2010 08:37 AM, Llu=C3=ADs wrote: >> I know extending the ISA is not nice at all, but I think that's much >> more maintainable than a per-guest OS interface (supposing some will >> need extra guest drivers). > On x86, there are some architecturally nicer ways to do this. > For instance, a CPUID leaf could be used in the 0x40001xxx range. Right, I commented this in a previous mail as a much nicer way to do it, but I was just too lazy to look up how CPUID works and instead ported the implementation I already had in bochs :) Although I can port it to CPUID if people find it useful to have upstream. I just need a way to provide an immediate and a register-based argument (at the same time), which does not require executing more than a couple of extra instructions (right now everything fits on a single instruction). Being able te receive back information would be a plus, which I think CPUID already does to return its results; although I think the ISA says that _all_ registers are "used" after executing it. Lluis --=20 "And it's much the same thing with knowledge, for whenever you learn something new, the whole world becomes that much richer." -- The Princess of Pure Reason, as told by Norton Juster in The Phantom Tollbooth