From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ua2-f43.google.com (mail-ua2-f43.google.com [74.125.226.235]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B4B55569F1C for ; Thu, 17 Sep 2026 14:02:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.226.235 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789653779; cv=none; b=i/8e5Oz8zrk46qJcKe22zY2Ka8e6zohvTkHeUuSKYIsrR0qMluOjPE4MPbz1xiyI2QSWP4YkEPXzPJ5qgOs9c7b/gyyJXC6eMfYKaMvydJ5BKD+OcCUs8yt1cnmfhY4PU0ldENhggWOz2a6isVWWPdU9NYPYb3SpL3xwX0+qCug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789653779; c=relaxed/simple; bh=5WF8VcNkm/QhAqH+TgnbaHxVovZYWfwOqxhhljrRvjc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VeTWUgtJVCucOTyQrMXR/v75dyPVjmgidxkYh5w0LEck6uP1jkGm8xnLycX1tkT8ULacklFMaxyeC9OrnOJ9+r2R3Qy/TuvGv6VPRUHKq1WU4RNKJbFflozUbFwa8hQJETTfYnq3+2hx23R4+DrZTL6uyuiNH4ikmvUkkgR4d44= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=OVEWn/ds; arc=none smtp.client-ip=74.125.226.235 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="OVEWn/ds" Received: by mail-ua2-f43.google.com with SMTP id a1e0cc1a2514c-97e9af41731so272076241.3 for ; Thu, 17 Sep 2026 07:02:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1789653775; x=1790258575; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :content-type:mime-version:references:message-id:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to:content-type; bh=5WF8VcNkm/QhAqH+TgnbaHxVovZYWfwOqxhhljrRvjc=; b=OVEWn/dsUGk0Myco3X13NbUxQ2N6DqBM+3t+cl0zpoHxP6xtU+yXBGIcmtWaZAW59F yPlozK/9GLNCzTZ16jyK8rZW54T0IkPSrvLHiFew2qITy1XBgR7SJxcgH6Iuin7S4TDl bSJnKhV8eIhYNUvNdY8qzrTjQU3NHE9fszm8w4B3e/REeJC6jZ7nG300iARqT04ZVJai UOYZzu3RZCp9zHqZHgyJioDFLuiqO255MyFWk1klwJHcB0FP3UDtSChNCxaTuMvm8oFV lnv5UYb5jN0zo+pl5fpPOG2xgvvKOvnZh3AfFvU9txO14Py8ReHD1/Yk/BGr+1H/fCiJ l0LA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789653775; x=1790258575; h=in-reply-to:content-transfer-encoding:content-disposition :content-type:mime-version:references:message-id:subject:cc:to:from :date:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=5WF8VcNkm/QhAqH+TgnbaHxVovZYWfwOqxhhljrRvjc=; b=D3eQ+Dl1oSIhPHbNMdzk9EciCASFTVvzyFrwMScCIoZhk1fbPjeBcINRbJiXe+yv2Y 11e3QAP+fHYdKzze56ZHpU55l1jcUxzdpBibe//jgY5uAh3qtqbF5Ce0Q1QBEkglLYeS efBeRN+w4R1B2+a9yv80qh2Qp5VnzimzzYCyT89CtT1YTPJ3gsLYNspwTLOtiXRW3LEi v7C3CSwE6pISyY2BtVCt/XbA9jMf3HYqsJZM4PU87gH9ydiLqb/Mcr8jT1Zx+EEvar95 CqKrQ/K96jY+LU1QUZPiU2dgCIR2M/imCQECGxRDIN18lUOIH+/A6ayBP1HxBkBWuQf2 KMlA== X-Forwarded-Encrypted: i=1; AKwUvBwUvV3pgAC67cQzLUWEZ80f0yhjnkYOM+KmKDjM6T/zltGeBZXxFZ8Qli7uTEm+riN8a4Rz6hp7p92s@vger.kernel.org X-Gm-Message-State: AFuF++ndh/y4mC/4B8tJoBhJ32+umqi8f0zvalvJOMwNYQbpNB76ydTT UpsDuJVgUyID90CrFTNZ5BWGYDotUijll9w9OHi+ee1eZ5FhZyhRbPy0RVb40xLKadc= X-Gm-Gg: AYBFou2l9QLjCqHqshQZFOC2TJ2Cdgtxf9p8vfSk90zz/AeL05FHSoPZf9cUrOzTzs0 9PStJoU19ymCwf71S70gF7D8A6+BTz8/C7JFOqkJ1bO8wGTqiJa4SD9Tqmzmdk6iVw3375rl3B8 gagly3nT3sT2DaYJ0tSeuc59xPnCuwGwGMR4aF0mAyNlkjV/ObTnciEld13ZrV+g5wlgLOwSoJC +uqDrtUl3ANq9NTYFZGpfPdR2RAznWCRDlQJS0FQmv0CHS9tV52EMwXu3QAcUi+t7R7ndNiqRzS wJdTY5kMnYx+DcBS2JQsVycf4T6HEaKn7gHsR7ciJsqrAfwFB9lUmxQLmhKh0qrB5aMKFI5kE7n W4S8KAXTWr5Y5ghkf0McpD0BX1K+LVmh7tcAAerDDNhtvXkpSrA/NpJY4wFRQFx8bOycDc9lf5W m8S2D/uGriN/wGwMp1ccejzi3WqjrqG7vKZ7Ap0H43A1I0/i2ryGwav1yHV9HVGeulH1ESm3mCn GpbdniyadsIQlQ9i/BDwp0Yr5BZ8NRITLwhtUcyFvzdwCNjGoL+K5ew X-Received: by 2002:a05:6102:a189:20b0:7a2:63d4:3d25 with SMTP id ada2fe7eead31-7a263d44d51mr364707137.32.1789653775451; Thu, 17 Sep 2026 07:02:55 -0700 (PDT) Received: from ziepe.ca (hlfxns010zw-159-2-239-150.pppoe-dynamic.high-speed.ns.bellaliant.net. [159.2.239.150]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-9123bec59fasm50600486d6.39.2026.09.17.07.02.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 07:02:54 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1x7ChR-0000000Co7R-3O0W; Thu, 17 Sep 2026 11:02:53 -0300 Date: Thu, 17 Sep 2026 11:02:53 -0300 From: Jason Gunthorpe To: Thomas =?utf-8?Q?Hellstr=C3=B6m?= Cc: Leon Romanovsky , Bjorn Helgaas , Logan Gunthorpe , Chaitanya Kulkarni , Greg Kroah-Hartman , Jens Axboe , Alex Williamson , Ankit Agrawal , Jonathan Corbet , Shuah Khan , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , Randy Dunlap , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, iommu@lists.linux.dev, Tushar Dave , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-rdma@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v6 18/18] RDMA/mlx5: Ask P2PDMA whether ATS takes a direct peer-to-peer route Message-ID: <20260917140253.GG3196566@ziepe.ca> References: <20260914-fix-p2p-acs-v4-0-v6-0-5ef07ec9ef06@nvidia.com> <20260914-fix-p2p-acs-v4-0-v6-18-5ef07ec9ef06@nvidia.com> <321890690ce83d1943b2f678bd9bee9b8c895b66.camel@linux.intel.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: <321890690ce83d1943b2f678bd9bee9b8c895b66.camel@linux.intel.com> On Thu, Sep 17, 2026 at 03:56:12PM +0200, Thomas Hellström wrote: > That is, a flag to tell the topology check that some transactions > *will* take the host-bridge path due to IOVA being used, and that the > computations including pci_p2pdma_distance() need to check whether that > is possible (checking whitelist etc.) and return the corresponding > THRU_HOST_BRIDGE mapping type. Translated transactions taking a short- > cut using the bus-address would then be hidden from the driver. I imagined it would work by the driver passing in what modes it supports and Intel GPU would simply pass in ATS only. Even something like mlx has variation, only some operations can opt into ATS, many others are never-ATS. Driver should not make statements like " *will* take the host-bridge path" since it has no idea. Jason