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 15:29:20 +0100 Message-ID: <1352212160.2155.18.camel@Solace> References: <5097FD2902000078000A66BF@nat28.tlf.novell.com> <5098E19D02000078000A697A@nat28.tlf.novell.com> <20121106094456.GA45690@ocelot.phlegethon.org> <1352203585.505.5.camel@Solace> <509915CD02000078000A6ABF@nat28.tlf.novell.com> <20121106135842.GB45690@ocelot.phlegethon.org> <50992A2302000078000A6B78@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0864760982664723963==" Return-path: In-Reply-To: <50992A2302000078000A6B78@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 (Xen.org)" , "wei.huang2@amd.com" , "Tim (Xen.org)" , xen-devel , "weiwang.dd@gmail.com" , "xiantao.zhang@intel.com" List-Id: xen-devel@lists.xenproject.org --===============0864760982664723963== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-kJcfQeVYWtlOdCqMcYmN" --=-kJcfQeVYWtlOdCqMcYmN Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2012-11-06 at 14:17 +0000, Jan Beulich wrote: > > Indeed. (Intel) IOMMU interrupts are suppressed until the softirq > > handler acknowledges the error, but if the softirq handler doesn't > > disable the device, it will take another IOMMU interrupt immediately. > > I thought the AMD side behaved eth same but clearly not -- I'll try to > > take a look at that later in the week. >=20 > I don't think AMD's behaves much different, it's just that for the > PPR case nothing is being done in that regard (and it's unclear > whether or under what circumstances a high rate of these could > occur). >=20 Indeed. I just double checked the code and yes, both faults and PPRs are handled that way, and new interrupts are disabled until the tasklet handles the request and re-enables them. The difference, as Jan is saying, is there is no PPR equivalent of disabling bus mastering that can ensure livelock safeness when it comes to them. Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-kJcfQeVYWtlOdCqMcYmN 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) iEYEABECAAYFAlCZHsAACgkQk4XaBE3IOsQ5PwCfZbNoOfbAeFrRQKS9Z5c6xZe5 WUgAnRkSP0OfFDQZMpo7tfRoJ5KBJjBE =GwTj -----END PGP SIGNATURE----- --=-kJcfQeVYWtlOdCqMcYmN-- --===============0864760982664723963== 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 --===============0864760982664723963==--