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[47.55.120.4]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8b3295c13ccsm148498285a.26.2025.11.20.05.20.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Nov 2025 05:20:46 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vM4ac-00000000gLM-0tBz; Thu, 20 Nov 2025 09:20:46 -0400 Date: Thu, 20 Nov 2025 09:20:46 -0400 From: Jason Gunthorpe To: Christian =?utf-8?B?S8O2bmln?= Cc: Leon Romanovsky , Bjorn Helgaas , Logan Gunthorpe , Jens Axboe , Robin Murphy , Joerg Roedel , Will Deacon , Marek Szyprowski , Andrew Morton , Jonathan Corbet , Sumit Semwal , Kees Cook , "Gustavo A. R. Silva" , Ankit Agrawal , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , Krishnakant Jaju , Matt Ochs , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, iommu@lists.linux.dev, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, kvm@vger.kernel.org, linux-hardening@vger.kernel.org, Alex Mastro , Nicolin Chen Subject: Re: [Linaro-mm-sig] [PATCH v8 06/11] dma-buf: provide phys_vec to scatter-gather mapping routine Message-ID: <20251120132046.GU17968@ziepe.ca> References: <20251111-dmabuf-vfio-v8-0-fd9aa5df478f@nvidia.com> <20251111-dmabuf-vfio-v8-6-fd9aa5df478f@nvidia.com> <8a11b605-6ac7-48ac-8f27-22df7072e4ad@amd.com> <20251119132511.GK17968@ziepe.ca> <69436b2a-108d-4a5a-8025-c94348b74db6@amd.com> <20251119193114.GP17968@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 71CCD140015 X-Stat-Signature: y7gijcc3ctczuunnw5q3toke8e4sqgah X-HE-Tag: 1763644848-983977 X-HE-Meta: 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 GcCWNy9L pdsOL9tHSPZUAeTKfJPpl0WaSl5Q+TfZS00uWnoIpzIIy2mgnjZLNOHS26+i5akxGpZCBOY6iyZ4f/RMoajg64muVhFk67QNA8xzAJDQ9Bk4B21mje6h9W0DQhEurVaALCD0BKbnJOo5UUd5LORgf60+iaFSw0HuqfBBPgNHri34kSEQGsc8EJJbI9aHd6BqPqYDqOONphGvVENVI3SDkFnseYJmuG368Jx6EOh723SdOVnaYe0+h2WRZQzp7PvwW/1oGnG2faqxI/Q57Pq9U4UziG4L7+FHLpEM8BdX0F+OW0CydiJsfKEvDszTidrEmXD8OEVWq+1RepjZz9PRs7YoPTtQqz850RHqUzSy+guVIoU++UTvlpvv9dgPlDQb5WKtN 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 Thu, Nov 20, 2025 at 08:08:27AM +0100, Christian König wrote: > >> The exporter should be able to decide if it actually wants to use > >> P2P when the transfer has to go through the host bridge (e.g. when > >> IOMMU/bridge routing bits are enabled). > > > > Sure, but this is a simplified helper for exporters that don't have > > choices where the memory comes from. > > That is extremely questionable as justification to put that in common DMA-buf code. FWIW we already have patches for a RDMA exporter lined up to use it as well. That's two users already... Jason