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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-51741d6a240sm60989871cf.18.2026.06.01.10.50.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Jun 2026 10:50:04 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wU6m4-000000027Uh-034u; Mon, 01 Jun 2026 14:50:04 -0300 Date: Mon, 1 Jun 2026 14:50:03 -0300 From: Jason Gunthorpe To: Keith Busch Cc: Christian =?utf-8?B?S8O2bmln?= , Zhiping Zhang , Alex Williamson , Leon Romanovsky , Sumit Semwal , Bjorn Helgaas , kvm@vger.kernel.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, Yochai Cohen , Yishai Hadas , Linus Torvalds Subject: Re: [PATCH v5 0/4] vfio/dma-buf: add TPH support for peer-to-peer access Message-ID: <20260601175003.GC2487554@ziepe.ca> References: <20260527121438.GJ2487554@ziepe.ca> <20260527123634.GK2487554@ziepe.ca> <71302a7a-6b9f-40da-af81-b1862dbd637a@amd.com> <8d9bb0b7-182d-4930-b683-d5d24da6b2ab@amd.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, May 29, 2026 at 02:31:30PM -0600, Keith Busch wrote: > On Fri, May 29, 2026 at 09:36:00AM +0200, Christian König wrote: > > On 5/29/26 08:34, Zhiping Zhang wrote: > > ... > > > There's no in-tree vendor PF driver > > > > Well I have to admit it's a bit on the edge but this sentence is a show stopper. > > > > DMA-buf is an in kernel interface for buffer sharing between drivers and any change to it needs an in kernel driver as justification for the added complexity. > > > > > - the device is a Meta MTIA > > > accelerator managed entirely from userspace via VFIO passthrough. > > > > When you have a complete open source driver stack which utilizes VFIO passthrough as the interface to communicate with the kernel drivers then we can eventually talk about that. > > > > But as far as I can see without upstreaming or at least open sourcing the full stack to utilize this functionality it's a clear NAK to upstreaming this. > > But the existing dmabuf for vfio-pci was accepted upstream without these > requirements. I see you had concerns about even that, but still Acked > under the same model that's propsed in this series: > > https://lore.kernel.org/linux-pci/57b8876f-1399-4e4d-a44b-1177787aa17d@amd.com/ To be fair that is quite different there isn't a proprietary userspace issue for that series, and there should be more users of the API when the GPU drivers migrate.. Jason