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[68.146.128.183]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23e3b6efb69sm85898495ad.195.2025.07.22.20.55.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Jul 2025 20:55:23 -0700 (PDT) Received: from jgg by jggl with local (Exim 4.95) (envelope-from ) id 1ueQZe-0003Gp-Gf; Wed, 23 Jul 2025 00:55:22 -0300 Date: Wed, 23 Jul 2025 00:55:22 -0300 From: Jason Gunthorpe To: Christoph Hellwig Cc: Yonatan Maman , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Andrew Morton , Leon Romanovsky , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Alistair Popple , Ben Skeggs , Michael Guralnik , Or Har-Toov , Daisuke Matsuda , Shay Drory , linux-mm@kvack.org, linux-rdma@vger.kernel.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, Gal Shalom Subject: Re: [PATCH v2 4/5] RDMA/mlx5: Enable P2P DMA with fallback mechanism Message-ID: References: <20250718115112.3881129-1-ymaman@nvidia.com> <20250718115112.3881129-5-ymaman@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Jul 21, 2025 at 12:03:41AM -0700, Christoph Hellwig wrote: > On Fri, Jul 18, 2025 at 02:51:11PM +0300, Yonatan Maman wrote: > > From: Yonatan Maman > > > > Add support for P2P for MLX5 NIC devices with automatic fallback to > > standard DMA when P2P mapping fails. > > That's now how the P2P API works. You need to check the P2P availability > higher up. How do you mean? This looks OKish to me, for ODP and HMM it has to check the P2P availability on a page by page basis because every single page can be a different origin device. There isn't really a higher up here... Jason