From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg.Roedel@amd.com (Roedel, Joerg) Date: Tue, 13 Sep 2011 12:00:34 +0200 Subject: [PATCH 1/3] iommu/core: add fault reporting mechanism In-Reply-To: References: <1315421604-12286-1-git-send-email-ohad@wizery.com> <20110912160252.GE11701@amd.com> Message-ID: <20110913100034.GJ11701@amd.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Sep 12, 2011 at 12:21:13PM -0400, Ohad Ben-Cohen wrote: > On Mon, Sep 12, 2011 at 7:02 PM, Roedel, Joerg wrote: > > I still don't get the need for this. It would make sense to encode > > different types of faults, like page-faults or interrupt-faults. > > Right. > > > When I read the comment above it sounds more like you want to encode > > different error-levels, like recoverable and unrecoverable error. > > The exact meaning of these values need to be clarified. > > Well, we currently only need to say "something bad has happened". > > We don't need at this point to tell whether it's a hardware bug, > inconsistent data, missing page-table entries or whatnot, because we > don't expect the user (or the iommu core itself) to do anything about > it. Not that it's not possible though: a valid response one day would > be to fix the page-table or add a missing TLB (depending on the mode > the hardware is configured to) but this is not (yet?) implemented. So > a "general unrecoverable error" is enough at this point, but it's > certainly makes sense to allow drivers to provide additional types of > errors/faults - once they are implemented. But besides real faults all this can be handled in the iommu-driver itself, right? So there is no need to communicate other errors than page-faults up to the driver. For now I think it is the best to remove this IOMMU_ERROR thing. It is inherent to the function call already. When a real use-case comes up we can easily add it later. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632