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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Phq6ne8jeiHRh+g/jyaIbVu24BslXtOFr5jlNeVkeq5Pd4JP4IP/urevgfTH7y8Ng IM4N1EVTTw6lIyVWLMQ5K0tdY5QpmQj79Qaao8gIoOMRohyP/vZ3M9ekEqXib6GZL+ Vd2t51G/uWQd6oD58QoSzV0VWLuJ8QqSIDQStXuXWQ5G8gEHsTZDXx81LTTpzH1daZ ezVZXuukAwl9TGk23btBxOterY1GjPt8BN4i8ULPTxzKhdnMZ1IhejtxHnXHMC5Wo6 rXCmw6UrvY7ectigm1BvmYyiZfOF9dlvJf0mlr92yHUxxT/i06Xv2nhdtuZ9olDn3p c3RNuuUGIqBAg== Date: Wed, 30 Jul 2025 11:03:17 +0300 From: Leon Romanovsky To: Logan Gunthorpe Cc: Jason Gunthorpe , Christoph Hellwig , Alex Williamson , Andrew Morton , Bjorn Helgaas , Christian =?iso-8859-1?Q?K=F6nig?= , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, Jens Axboe , =?iso-8859-1?B?Suly9G1l?= Glisse , Joerg Roedel , kvm@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Marek Szyprowski , Robin Murphy , Sumit Semwal , Vivek Kasireddy , Will Deacon Subject: Re: [PATCH 05/10] PCI/P2PDMA: Export pci_p2pdma_map_type() function Message-ID: <20250730080317.GO402218@unreal> References: <82e62eb59afcd39b68ae143573d5ed113a92344e.1753274085.git.leonro@nvidia.com> <20250724080313.GA31887@lst.de> <20250724081321.GT402218@unreal> <20250727190514.GG7551@nvidia.com> <20250728164136.GD402218@unreal> <20250728231107.GE36037@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B5A5B160013 X-Stat-Signature: 4gogs5fi1dmnqopcokwbiair8ctakmea X-HE-Tag: 1753862604-86386 X-HE-Meta: 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 fMJz+mDE AAwFkd6yX0/z0luaFSami+Bo6S3jB1fGgOlXUdSiaqCSpH5CoaxFdZ95Uiy7yZshKrsQJrtHTyu+BRl6F1HQkOY4Zrv3B8a46jkntzHje/uXVnjmOHD2n12x1kChmPCPhUMsPmpSJs1EfxOytV6gVb1+2FnVeiQc+cblBkCwlwuhgWwDy24WpvtJN57Ts62Pp+GG4GqMCWlstwl9Dp5rXB9opkdrIoO92/HCdDdiV+qyzmmKCpfJY90jGmExlX3MDH1Aja9bn98sq6XjZkkOrX1x15xMk4xkNwoOE+62pmmsD2k0= 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, Jul 29, 2025 at 02:54:13PM -0600, Logan Gunthorpe wrote: > > > On 2025-07-28 17:11, Jason Gunthorpe wrote: > >> If the dma mapping for P2P memory doesn't need to create an iommu > >> mapping then that's fine. But it should be the dma-iommu layer to decide > >> that. > > > > So above, we can't use dma-iommu.c, it might not be compiled into the > > kernel but the dma_map_phys() path is still valid. > > This is an easily solved problem. I did a very rough sketch below to say > it's really not that hard. (Note it has some rough edges that could be > cleaned up and I based it off Leon's git repo which appears to not be > the same as what was posted, but the core concept is sound). I started to prepare v2, this is why posted version is slightly different from dmabuf-vfio branch. In addition to what Jason wrote. there is an extra complexity with using state. The wrappers which operate on dma_iova_state assume that all memory, which is going to be mapped, is the same type: or p2p or not. This is not the cased for HMM/RDMA users, there you create state in advance and get mixed type of pages. Thanks