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b=ce0nhRfsh4foP8kliSiSC0eCyy1P530wNZv1yXlz0fhnntdzc2pHj8ehJ73sKloVM C0cw7cUj+BIc9kmwIU3OVnx2X/5KZolUkXS2nrcBmOD80XEOnwWEu+qaNld4IC1Lbz ktTwM4BKKx5FIv7O9NfsPq2v7mz23KDqI6mFjPh6003pPohStRGfOcfyHzqdAMOVmD 1gOusmiwUbvZzBP/fZDRftY7IT+SckUkPyIVGM5JFjlw/2fk+9/Ns880REt1nFz5Or pRuSFvVxXKUnth/AX3auD+qu9VK2N7OyoDzrtCOl5aOlD0WNxZyXTU1dmfK4K2DInq 5BLO5MT41pJgw== Date: Mon, 31 Mar 2025 18:09:27 -0700 From: Luis Chamberlain To: Leon Romanovsky , Daniel Gomez Cc: Jason Gunthorpe , Robin Murphy , Christoph Hellwig , Jens Axboe , Joerg Roedel , Will Deacon , Sagi Grimberg , Keith Busch , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , Marek Szyprowski , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrew Morton , Jonathan Corbet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Randy Dunlap Subject: Re: [PATCH v7 00/17] Provide a new two step DMA mapping API Message-ID: References: <20250220124827.GR53094@unreal> <1166a5f5-23cc-4cce-ba40-5e10ad2606de@arm.com> <20250302085717.GO53094@unreal> <20250325144158.GA4558@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250325144158.GA4558@unreal> X-Stat-Signature: z9uw6eqs8r1oy6qy4bydbn7rr4iagz9c X-Rspam-User: X-Rspamd-Queue-Id: 3D7C1140008 X-Rspamd-Server: rspam08 X-HE-Tag: 1743469771-622091 X-HE-Meta: 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 /VSHIuEj AwBIVpCByAwWsqTZsNOWkspWkdy5pJ9W1D6XI0fQN7QBRUzwiFxnsB5S1YB/2WdylYt9HYnmBw6QM/xnvp7Ju0TdwGL1YKO+AuvnZ33nj1gVT2hRxVvx5PHWe8NFg71DklQ+PmQxk2gr50+sk01h2WJno2ft4xDnaevo2pX1EhjwR4agl6bCocYaWsshJx44X5w6k8XPzkq9943RlfPxwBI6gtPv1VvL1FCZ3Vai1OGR3Du2zQIO2eVGrzzUdWG9NAdUadLCKTNd4JSTiUhRa5HeY3d7L9bzsGa1SfxiMl5ymHE8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 25, 2025 at 04:41:58PM +0200, Leon Romanovsky wrote: > On Tue, Mar 25, 2025 at 09:36:37AM -0300, Jason Gunthorpe wrote: > > On Fri, Mar 21, 2025 at 04:05:22PM +0000, Robin Murphy wrote: > > <...> > > > > So what is it now, a layering violation in a hat with still no clear path to > > > support SWIOTLB? > > > > I was under the impression Leon had been testing SWIOTLB? > > Yes, SWIOTLB works We will double check too. > and Christoph said it more than once that he tested > NVMe conversion patches and they worked. We've taken this entire series and the NVMe patches and have built on top of them. The nvme-pci driver does not have scatter list chaining support, and we don't want to support that because it is backwards. Instead, the two step DMA API lets us actually remove all that scatter list cruft and provide a single solution for direct IO and io-uring command passthrough to support large IOs [0] [1] and logical block sizes up to 2 MiB. We continue to plan to work on this and are happy to test this further. Clearly, we don't want any regressions on NVMe. [0] https://lore.kernel.org/all/20250320111328.2841690-1-mcgrof@kernel.org/ [1] https://lore.kernel.org/all/Z9v-1xjl7dD7Tr-H@bombadil.infradead.org/ Luis