From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH] IOMMU: don't disable bus mastering on faults for devices used by Xen or Dom0 Date: Tue, 6 Nov 2012 13:08:47 +0100 Message-ID: <1352203727.505.7.camel@Solace> References: <5097FD2902000078000A66BF@nat28.tlf.novell.com> <5098E19D02000078000A697A@nat28.tlf.novell.com> <20121106094456.GA45690@ocelot.phlegethon.org> <5098F22C02000078000A69E2@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4758811756323479261==" Return-path: In-Reply-To: <5098F22C02000078000A69E2@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: Keir Fraser , wei.huang2@amd.com, Tim Deegan , xen-devel , weiwang.dd@gmail.com, xiantao.zhang@intel.com List-Id: xen-devel@lists.xenproject.org --===============4758811756323479261== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-qjCvdL3sFjS0q5TwGI2f" --=-qjCvdL3sFjS0q5TwGI2f Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2012-11-06 at 10:19 +0000, Jan Beulich wrote: > > This check is really there to stop a mad device from hosing the system > > rather than to contain a malicious OS, and a properly out-of-control > > device needs to be stopped or it will livelock Xen with iommu faults. > > In a uniprocessor system, dom0 might never get the chance to fix it. >=20 > If that's the main goal, then on the AMD side the code may not do > what you want it to: PPR log entries, causing interrupts too, don't > get limited/suppressed in any way, yet are obviously to some > extent under guest control. >=20 IIRC, PPR are dealt with in softirq context too, aren't they? > But yes, for the purpose here limiting the fault rate in some way > (with a slightly higher limit for Dom0 than DomU-s) would indeed > be the better route. >=20 BTW, yes, independently from the above and for what it counts, I agree with this. Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-qjCvdL3sFjS0q5TwGI2f Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEUEABECAAYFAlCY/c8ACgkQk4XaBE3IOsRRxQCfZPl9HnbbA1dM660HuWLHh5FC 33gAmMDPlzzFkl53B0Q3VOnJk6roRc0= =b/A1 -----END PGP SIGNATURE----- --=-qjCvdL3sFjS0q5TwGI2f-- --===============4758811756323479261== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============4758811756323479261==--