From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F50A23EA87 for ; Tue, 10 Feb 2026 19:47:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=67.231.145.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770752857; cv=none; b=dXQ3bDjQfzDWrYycKtOpgDtcNWjFSznipHXHqTxI81mRbCuMu3atYzUsmEYU3NItx8GfgN+G0GSd7aF2rsa5AxdHqyiO9rAqBv0lo854cgtAx9qlIQAtIqFQ37yotnmv0CgTj24LUZlN1iaRpKrq8/XAjUhQ+3sFK276SNSMpmY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770752857; c=relaxed/simple; bh=EfVHrbdF8/yG09IBQ20HHyfnxAzay8Gf5YSnWq6tV7k=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=c5am0qTPTQBJV1X8TZUMyrK+xNB9CJFubVL/tFM4u3Dxdzjm7gjAVqZ5/l9uOPcWRjXYCNLW5gzsxRxltlgKP7Vk3zkwzQwVRS0q4YoRNP5G/rqoDe/vEFB4zr/BjV5WdLcTFaFO1l/X3irWvIOyfLsRSljwYoyRyiz9PMd2aR0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com; spf=pass smtp.mailfrom=meta.com; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b=DO9mt+Uy; arc=none smtp.client-ip=67.231.145.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=meta.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b="DO9mt+Uy" Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 61AH2Jvi3309800 for ; Tue, 10 Feb 2026 11:47:35 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=cc :content-transfer-encoding:content-type:date:from:message-id :mime-version:subject:to; s=s2048-2025-q2; bh=EfVHrbdF8/yG09IBQ2 0HHyfnxAzay8Gf5YSnWq6tV7k=; b=DO9mt+Uy0AavnJKPFVpdQFeFx7wmTdy+q4 9Zd4SKKQmT5Vxv/2WmpU1HS840cw6ba7ngN9cPfRzgPKdITOFHsdorYD8x6x+E4m 1JXQPhMDSMeQz1TiJo6rLGQBRGPcwf2G6EZvZ/rF8Mb470XJw1z4qXOf3WytmD8o 2v6WbvmjIRztxj9f2688BRhkKu6wbvK91YJAxi/+SvtOl9qZ9RloccAoR5iNuFfz OqmYtB9XrvDMETixsQRtZAvOAw0mIGENvnNHToGezVLrFU6uZx/fZg4Xiu1uXGYY 9vhVznJJFygEAulULtYOW5eOVYweFnOQor9hPvNVDgKyDc3wOxIQ== Received: from mail.thefacebook.com ([163.114.134.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 4c88qnjd9p-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 10 Feb 2026 11:47:35 -0800 (PST) Received: from twshared41309.15.frc2.facebook.com (2620:10d:c085:208::7cb7) by mail.thefacebook.com (2620:10d:c08b:78::c78f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.35; Tue, 10 Feb 2026 19:47:34 +0000 Received: by devbig259.ftw1.facebook.com (Postfix, from userid 664516) id DCAA7102666AF; Tue, 10 Feb 2026 11:40:15 -0800 (PST) From: Zhiping Zhang To: Jason Gunthorpe , Leon Romanovsky , Bjorn Helgaas , , , , , Keith Busch , Yochai Cohen , Yishai Hadas CC: Bjorn Helgaas , Zhiping Zhang 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: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjEwMDE2MyBTYWx0ZWRfX6MWXPWu8HDSC NtxV2/CFMdbaPQPhdNA2lMnjzpvjyL+njPH3BjXxyt1Cm5GA212kHWijIXJPOD3dhaF5UhLQHhD IjYeTXDpDoe13U0j6Rc+20i6ftQLmcSUeczBPVvPo1RlBHqcl0oFWFleGRUT7r0XoE0Vgy/S6BI uL1BW/f6rKmPyj1whkAP2KawgHzN9a5eivUmva5s76Z9AsWLficwNGs1gjusUd8671w8lQXmV7l BRRqJGORn2OMXB/kAN9quPeJnfn/UvwBiSi+4VRdKlZ/0dd3wWBm/AC7/zm0AeOukl1w2YpYZtY QXz45v5Enz/XR6Wru2zgFTovtaHPRAfZWo5ZimZgciin9bNA5u5W2/LaVXPJIu1bbfrjfLqKjns Tc87HDNBIUyEZlr3Gl8OIAofQlZ3F/WVhFlMe0Mlg3Y4zQ3I3CQHOc6ULl1q4+KY5YXg9mmQrvd 9YApwPWgl121KH6x55A== X-Authority-Analysis: v=2.4 cv=POkCOPqC c=1 sm=1 tr=0 ts=698b8b57 cx=c_pps a=CB4LiSf2rd0gKozIdrpkBw==:117 a=CB4LiSf2rd0gKozIdrpkBw==:17 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VabnemYjAAAA:8 a=yWaUcmrBNUFKcz5DFYsA:9 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-ORIG-GUID: dk0XhbpL3MjQDloj1HHkXIbe66t_DotB X-Proofpoint-GUID: dk0XhbpL3MjQDloj1HHkXIbe66t_DotB X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-10_03,2026-02-10_02,2025-10-01_01 Currently, the steering tag can be used for a CPU on the motherboard; the ACPI check is in place to query and obtain the supported tph settings. He= re we intend to use the tph info to improve RDMA NIC memory access on a vfio= -based accelerator device via PCIe peer-to-peer. When an applicantion register a RDMA memory region with DMABUF for the RDMA NIC to access the device memo= ry, the tph associated with the memory region can be retrieved and used to se= t the steering tag / process hint (ph). The tph contains additional instruction= s or hints to the GPU or accelerator device for advanced memory operations, such as, read cache selection. Note this RFC is for the discussion on the direction and is not intended = to be a complete implementation. Once the direction is agreed on, we will work = on the implementation or a real patch set. Signed-off-by: Zhiping Zhang [RFC 1/2] Vfio: add callback to get tph info for dmabuf [RFC 2/2] RMDA MLX5: get tph for p2p access when registering dmabuf