From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Roedel, Joerg" Subject: Re: [PATCH v3 1/6] iommu/core: split mapping to page sizes as supported by the hardware Date: Tue, 11 Oct 2011 12:19:36 +0200 Message-ID: <20111011101936.GD2138@amd.com> References: <20110927100505.GH2138@amd.com> <20110927131222.GL2138@amd.com> <20110927181438.GM2138@amd.com> <20111010094738.GW2138@amd.com> <20111010153609.GB2138@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: "iommu@lists.linux-foundation.org" , "linux-omap@vger.kernel.org" , Laurent Pinchart , David Woodhouse , "linux-arm-kernel@lists.infradead.org" , David Brown , Arnd Bergmann , "linux-kernel@vger.kernel.org" , Stepan Moskovchenko , "kvm@vger.kernel.org" , Hiroshi Doyu To: Ohad Ben-Cohen Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Hi Ohad, On Mon, Oct 10, 2011 at 01:02:46PM -0400, Ohad Ben-Cohen wrote: > On Mon, Oct 10, 2011 at 5:36 PM, Roedel, Joerg wrote: > > Yes, somthing like that. Probably the iommu_ops->unmap function should > > be turned into a unmap_page function call which only takes an iova and > > no size parameter. The iommu-driver unmaps the page pointing to that > > iova and returns the size of the page unmapped. This still allows the > > simple implementation for the unmap-call. > > Yes, exactly. It will take some time to migrate all drivers (today we > have 4 drivers, each of which is implementing a slightly different > ->unmap() semantics), but at least let's not accept any new driver > that doesn't adhere to this, otherwise it's going to be even harder > for the API to evolve. Agreed. We should change the existing drivers one-by-one. > > We don't need to really enforce the calls to be symetric. But we can > > define that we only give the guarantee about what will be unmapped > > when the calls are symetric. > > Sounds good to me. I'll add this to the kernel doc patch (which I'll > submit after this patch set materializes), and when/if we move to > symmetric only, we will update it. Great. So if no one disagrees with this direction (this means all the other people on Cc :) ) it is the way to. 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