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Mon, 20 Apr 2020 00:42:22 -0700 (PDT) Date: Mon, 20 Apr 2020 09:42:13 +0200 From: Jean-Philippe Brucker To: Christoph Hellwig Subject: Re: [PATCH v5 02/25] iommu/sva: Manage process address spaces Message-ID: <20200420074213.GA3180232@myrica> References: <20200414170252.714402-1-jean-philippe@linaro.org> <20200414170252.714402-3-jean-philippe@linaro.org> <20200416072852.GA32000@infradead.org> <20200416085402.GB1286150@myrica> <20200416121331.GA18661@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200416121331.GA18661@infradead.org> Cc: devicetree@vger.kernel.org, kevin.tian@intel.com, jgg@ziepe.ca, linux-pci@vger.kernel.org, robin.murphy@arm.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, catalin.marinas@arm.com, zhangfei.gao@linaro.org, will@kernel.org, christian.koenig@amd.com, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, Apr 16, 2020 at 05:13:31AM -0700, Christoph Hellwig wrote: > On Thu, Apr 16, 2020 at 10:54:02AM +0200, Jean-Philippe Brucker wrote: > > On Thu, Apr 16, 2020 at 12:28:52AM -0700, Christoph Hellwig wrote: > > > > + rcu_read_lock(); > > > > + hlist_for_each_entry_rcu(bond, &io_mm->devices, mm_node) > > > > + io_mm->ops->invalidate(bond->sva.dev, io_mm->pasid, io_mm->ctx, > > > > + start, end - start); > > > > + rcu_read_unlock(); > > > > +} > > > > > > What is the reason that the devices don't register their own notifiers? > > > This kinds of multiplexing is always rather messy, and you do it for > > > all the methods. > > > > This sends TLB and ATC invalidations through the IOMMU, it doesn't go > > through device drivers > > I don't think we mean the same thing, probably because of my rather > imprecise use of the word device. > > What I mean is that the mmu_notifier should not be embedded into the > io_mm structure (whch btw, seems to have a way to generic name, just > like all other io_* prefixed names), but instead into the > iommu_bond structure. That avoid the whole multiplexing layer. Right, I can see the appeal. I still like having a single mmu notifier per mm because it ensures we allocate a single PASID per mm (as required by x86). I suppose one alternative is to maintain a hashtable of mm->pasid, to avoid iterating over all bonds during allocation. Thanks, Jean _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu