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{ "id": 2195335, "url": "http://patchwork.ozlabs.org/api/covers/2195335/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/cover/20260210194014.2147481-1-zhipingz@meta.com/", "project": { "id": 28, "url": "http://patchwork.ozlabs.org/api/projects/28/?format=api", "name": "Linux PCI development", "link_name": "linux-pci", "list_id": "linux-pci.vger.kernel.org", "list_email": "linux-pci@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260210194014.2147481-1-zhipingz@meta.com>", "list_archive_url": null, "date": "2026-02-10T19:39:53", "name": "[RFC,0/2] Retrieve tph from dmabuf for PCIe P2P memory access", "submitter": { "id": 92088, "url": "http://patchwork.ozlabs.org/api/people/92088/?format=api", "name": "Zhiping Zhang", "email": "zhipingz@meta.com" }, "mbox": "http://patchwork.ozlabs.org/project/linux-pci/cover/20260210194014.2147481-1-zhipingz@meta.com/mbox/", "series": [ { "id": 491732, "url": "http://patchwork.ozlabs.org/api/series/491732/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/list/?series=491732", "date": "2026-02-10T19:39:53", "name": "Retrieve tph from dmabuf for PCIe P2P memory access", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/491732/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2195335/comments/", "headers": { "Return-Path": "\n <linux-pci+bounces-47114-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-pci@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=meta.com header.i=@meta.com header.a=rsa-sha256\n header.s=s2048-2025-q2 header.b=DO9mt+Uy;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.105.105.114; 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arc=none smtp.client-ip=67.231.145.42", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=cc\n\t:content-transfer-encoding:content-type:date:from:message-id\n\t:mime-version:subject:to; s=s2048-2025-q2; bh=EfVHrbdF8/yG09IBQ2\n\t0HHyfnxAzay8Gf5YSnWq6tV7k=; b=DO9mt+Uy0AavnJKPFVpdQFeFx7wmTdy+q4\n\t9Zd4SKKQmT5Vxv/2WmpU1HS840cw6ba7ngN9cPfRzgPKdITOFHsdorYD8x6x+E4m\n\t1JXQPhMDSMeQz1TiJo6rLGQBRGPcwf2G6EZvZ/rF8Mb470XJw1z4qXOf3WytmD8o\n\t2v6WbvmjIRztxj9f2688BRhkKu6wbvK91YJAxi/+SvtOl9qZ9RloccAoR5iNuFfz\n\tOqmYtB9XrvDMETixsQRtZAvOAw0mIGENvnNHToGezVLrFU6uZx/fZg4Xiu1uXGYY\n\t9vhVznJJFygEAulULtYOW5eOVYweFnOQor9hPvNVDgKyDc3wOxIQ==", "From": "Zhiping Zhang <zhipingz@meta.com>", "To": "Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>,\n Bjorn\n Helgaas <bhelgaas@google.com>, <linux-rdma@vger.kernel.org>,\n <linux-pci@vger.kernel.org>, <netdev@vger.kernel.org>,\n <dri-devel@lists.freedesktop.org>, Keith Busch <kbusch@kernel.org>,\n Yochai\n Cohen <yochai@nvidia.com>, Yishai Hadas <yishaih@nvidia.com>", "CC": "Bjorn Helgaas <helgaas@kernel.org>, Zhiping Zhang <zhipingz@meta.com>", "Subject": "[RFC 0/2] Retrieve tph from dmabuf for PCIe P2P memory access", "Date": "Tue, 10 Feb 2026 11:39:53 -0800", "Message-ID": "<20260210194014.2147481-1-zhipingz@meta.com>", "X-Mailer": "git-send-email 2.47.3", "Precedence": "bulk", "X-Mailing-List": "linux-pci@vger.kernel.org", "List-Id": "<linux-pci.vger.kernel.org>", "List-Subscribe": "<mailto:linux-pci+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-pci+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "quoted-printable", "X-FB-Internal": "Safe", "Content-Type": "text/plain", "X-Proofpoint-Spam-Details-Enc": "AW1haW4tMjYwMjEwMDE2MyBTYWx0ZWRfX6MWXPWu8HDSC\n NtxV2/CFMdbaPQPhdNA2lMnjzpvjyL+njPH3BjXxyt1Cm5GA212kHWijIXJPOD3dhaF5UhLQHhD\n IjYeTXDpDoe13U0j6Rc+20i6ftQLmcSUeczBPVvPo1RlBHqcl0oFWFleGRUT7r0XoE0Vgy/S6BI\n uL1BW/f6rKmPyj1whkAP2KawgHzN9a5eivUmva5s76Z9AsWLficwNGs1gjusUd8671w8lQXmV7l\n BRRqJGORn2OMXB/kAN9quPeJnfn/UvwBiSi+4VRdKlZ/0dd3wWBm/AC7/zm0AeOukl1w2YpYZtY\n QXz45v5Enz/XR6Wru2zgFTovtaHPRAfZWo5ZimZgciin9bNA5u5W2/LaVXPJIu1bbfrjfLqKjns\n Tc87HDNBIUyEZlr3Gl8OIAofQlZ3F/WVhFlMe0Mlg3Y4zQ3I3CQHOc6ULl1q4+KY5YXg9mmQrvd\n 9YApwPWgl121KH6x55A==", "X-Authority-Analysis": "v=2.4 cv=POkCOPqC c=1 sm=1 tr=0 ts=698b8b57 cx=c_pps\n a=CB4LiSf2rd0gKozIdrpkBw==:117 a=CB4LiSf2rd0gKozIdrpkBw==:17\n a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22\n a=GgsMoib0sEa3-_RKJdDe:22 a=VabnemYjAAAA:8 a=yWaUcmrBNUFKcz5DFYsA:9\n a=gKebqoRLp9LExxC7YDUY:22", "X-Proofpoint-ORIG-GUID": "dk0XhbpL3MjQDloj1HHkXIbe66t_DotB", "X-Proofpoint-GUID": "dk0XhbpL3MjQDloj1HHkXIbe66t_DotB", "X-Proofpoint-Virus-Version": "vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-02-10_03,2026-02-10_02,2025-10-01_01" }, "content": "Currently, the steering tag can be used for a CPU on the motherboard; the\nACPI check is in place to query and obtain the supported tph settings. Here\nwe intend to use the tph info to improve RDMA NIC memory access on a vfio-based\naccelerator device via PCIe peer-to-peer. When an applicantion register a\nRDMA memory region with DMABUF for the RDMA NIC to access the device memory,\nthe tph associated with the memory region can be retrieved and used to set the\nsteering tag / process hint (ph). The tph contains additional instructions\nor hints to the GPU or accelerator device for advanced memory operations,\nsuch as, read cache selection.\n\nNote this RFC is for the discussion on the direction and is not intended to be\na complete implementation. Once the direction is agreed on, we will work on the\nimplementation or a real patch set.\n\nSigned-off-by: Zhiping Zhang <zhipingz@meta.com>\n\n[RFC 1/2] Vfio: add callback to get tph info for dmabuf\n[RFC 2/2] RMDA MLX5: get tph for p2p access when registering dmabuf" }