From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 59700F9EDC0 for ; Wed, 22 Apr 2026 12:39:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B0FE810E2A5; Wed, 22 Apr 2026 12:39:35 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=amd.com header.i=@amd.com header.b="WoGq1UKp"; dkim-atps=neutral Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazon11011002.outbound.protection.outlook.com [40.93.194.2]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7A2CB10E2A5; Wed, 22 Apr 2026 12:39:34 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=jxayQ42uIpfC5JjSS65xUGo8BRkOxvXT2k0hO3qR8HZNLhp86iUduXZLReA6waBAOShGjlUM527SAcnUKk5VE29mpOJ3GaTOh/h47gdZqcMfNwpeWCPwg7tXrbKwtYtMqAQDRuODMRpiwDxiok5BcqcJyrP8akAJ7nZ0EP4bZkL1+lWqJPqHv1T3Bafz13yzmukW/uWopkwUOyPQRT49pkXjw5unv8gr8Y00vo27q6TjklxQAwNsU3OEFOArmCgJCoBf744EDmnBstKH58xHe//8IMemauSwDrWzhkdd0Cf49KLSwExDLCXa0WcDYc1FKi5iYkaj1Op37KdNPMz/XA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=MMTkXQIsan3SLJhhkBaUokqyVzkv9bCTYB1PHyCN8Yc=; b=DE6NaRQ/Pb61aOboQ7CuFmmXcryCmJw9xg6MGrfhgDiPkQLjiTENRbrRRAb8Ilt5PA7BThq2hF4rIRq5WQPM9DfF9MO7VUmAgzxvLel4egSVbyudcL0/meLy28zGacwXsyPPsR2aLKHZiE+XfOffLT1nCQor11jPb5y8SV1S6F4EfACI6bGrxycoNc29CqzQny6NR56dkaKr/W45KmjxqZ6+3T6bspsmq+j3Vt85uYyuMsFVlBNOxcKBvwUUFkOuvig0XSw5B3COEudiHwG7GhkvxRMbGHd/NCM5nla2ZJZb+5T602ANKr35imcRC5aTHYYYXA3/3qFoCyTAU904+Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=MMTkXQIsan3SLJhhkBaUokqyVzkv9bCTYB1PHyCN8Yc=; b=WoGq1UKp6Q1Gcf7gaadmfVZxGRooz/reYyQMBxhzWS6ixwgwnSyT5tkgYVCizEqEucl6e+8lSULkRmRF3AqBbugcQHcRYfXnR13LkR010C7tF0Hx1Ld/S4O5UwBX+w1YbUBHcJYGcCgl+tF1vwfulgQxNZ1v8lJeGdIqFNe1nRM= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from PH7PR12MB5685.namprd12.prod.outlook.com (2603:10b6:510:13c::22) by PH7PR12MB5594.namprd12.prod.outlook.com (2603:10b6:510:134::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9846.20; Wed, 22 Apr 2026 12:39:30 +0000 Received: from PH7PR12MB5685.namprd12.prod.outlook.com ([fe80::ce69:cfae:774d:a65c]) by PH7PR12MB5685.namprd12.prod.outlook.com ([fe80::ce69:cfae:774d:a65c%5]) with mapi id 15.20.9846.016; Wed, 22 Apr 2026 12:39:30 +0000 Message-ID: Date: Wed, 22 Apr 2026 14:39:16 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 21/26] dma-buf: Add the Physical Address List DMA mapping type To: Jason Gunthorpe Cc: Dongwon Kim , dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, iommu@lists.linux.dev, Kevin Tian , Leon Romanovsky , linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, Matthew Brost , Simona Vetter , Sumit Semwal , Thomas Hellstrom , Vivek Kasireddy References: <21-v1-b5cab63049c0+191af-dmabuf_map_type_jgg@nvidia.com> <20260413121628.GE2588311@nvidia.com> <20260422115306.GI3199414@nvidia.com> Content-Language: en-US From: =?UTF-8?Q?Christian_K=C3=B6nig?= In-Reply-To: <20260422115306.GI3199414@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MN2PR20CA0066.namprd20.prod.outlook.com (2603:10b6:208:235::35) To PH7PR12MB5685.namprd12.prod.outlook.com (2603:10b6:510:13c::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR12MB5685:EE_|PH7PR12MB5594:EE_ X-MS-Office365-Filtering-Correlation-Id: dcf9bd2a-ba10-4971-8e84-08dea06c32a1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; ARA:13230040|366016|7416014|1800799024|376014|18002099003|22082099003|56012099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:PH7PR12MB5685.namprd12.prod.outlook.com; PTR:; CAT:NONE; SFS:(13230040)(366016)(7416014)(1800799024)(376014)(18002099003)(22082099003)(56012099003); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?OEUvZHh5V2FQSmpUZG5YTW9nZFUxcG5iaG4zYmlzeXN4MEJhVkVmR2hVYnR4?= =?utf-8?B?UFVvUnF4MGhiR3ZkODFod09uekNMTmh6UTZJKzRRazNPVnR2Z2plTjN1anI4?= =?utf-8?B?NEROOVlMZXZsNWRKL1U3R1IrK2RsS0FxS2JDUS9TZ2pFd1AzM1VMSmtQQ0tN?= =?utf-8?B?S3h3ZTljUUpxNnROeEVzUXdzRjdBQ0IyM2pEZXZ2MDhINmZPcWR6TG9WZk9R?= =?utf-8?B?WVlJZWpKM3Y2d0lMR0I2bmtadUtRQXA1bmZ6WnZSdnE4U1hMOHBYUTlDVVRC?= =?utf-8?B?YjFEcmtiMjFmdHZ0eWZEM3lMbEhTQnJBbncwT3V2R1pSdlpIcEZXR09DWWpI?= =?utf-8?B?NWVzL0h4VWRqVGUzcGRyTldvZDZmSzJsaGQvNkl2aXBKMXFTaFQ0RFRUOENs?= =?utf-8?B?ZW5ZYU9sOVNETjNBS1NUN1FWUnJibTZXaFU5WCtqQTlXRmNWRVkyUllTSFRR?= =?utf-8?B?Q1U0ZTM3NlJodDZQSUN3SVQrRGJqeTdveVFjL0JrNkV6TnpPdU9NUlMyRGh5?= =?utf-8?B?K2YxR1RDb05iUlJtWHVNbVRHamhyRkxQVXpyZUlPcGViY2c1VnJYdUlkZ0pX?= =?utf-8?B?WWVsK1N0SVd1OUUzY3plVHFHdHNLUWYyL05Ic21nWDZPVVVnYzNNbHFoRGhC?= =?utf-8?B?NEp3d1R0NnFoUWNOSG9ZMGhsTHZyU3h4Y29hay9wVzlmeFdJUWpGVlZuMWdj?= =?utf-8?B?cVNlQWtqTmhrMVo5eGUxSm5zaUhPd0Z6Q0RvNCtkbjFEYVRQaCs5N01LMFhD?= =?utf-8?B?QU1uYzNvaTJLZE5TdUZBWUxiTHFHVElDK0dJTjMzTFJia1hxeEczZmQ5MHpi?= =?utf-8?B?WWtqcjNzSDFHemE0MGpkRXo3Vm01OFg1d3RETWJMUkw3MVdyZGNzS0hVZVow?= =?utf-8?B?VUJ5akVXM1Q5WCt5Um5wa1VXWXhUb2k0UDF5am5xcWY4YjBMbmRVN1Y1bG1C?= =?utf-8?B?NUlxRmFyK0JBNjdDSmtxWXNNK3lqenNQVG1YWkVSY0RSUEpPQmtIQk5Yd2F5?= =?utf-8?B?RWFVNXBoTTY5cHN3SWxyS0lLQjRiN29VdUUydHUvd3pMbmlyMnhQREJQOEVr?= =?utf-8?B?WG44MXArbjdXdmxaajdya3ZNckxUbG8rNE14bmF5a0lTWlFCcmNPVE9LZmZS?= =?utf-8?B?RTg3ZUQvQUN2aUJQMDFmWlBSR1RIT2VEanRNK0NFbmd4Sk1EMExiYkc5WnJo?= =?utf-8?B?L3BGbDB3aGJqblc3MjVPWHF5NUxCaTN1T3JOc2VFOTFMQnBkYUJmWEdCTE5G?= =?utf-8?B?bWJQa2xTcDlTR2w4cTZzbzB0ai94KytGeFBiY0JudkYwODlOL0hBRk13ZVd1?= =?utf-8?B?RFlYWFdrZnlyTzdLYStxK05uN0dZYmtxR2laOHFZc1ZNNDJnWm0xblRJNHBa?= =?utf-8?B?NEo3RUZBTVlvUlRqaTk2UGRob0orY0hDT2M5bnZLSDJ3NTRodnl4cTdUVitK?= =?utf-8?B?VkJ5MjlGdkdSVHFDZmJuT2ZPZmVKR3EzYlFWOFNtczJibWN1aGk3TTdSYWJD?= =?utf-8?B?akZESWNOMkdEZE5UNVVUanVZRzZGa0JRenVNZDlhRWQvUW1JTS9lQmdCdlV5?= =?utf-8?B?enF4bFQrUVZQODZQNHZWS3ZzRjVTMVpsRm1QcHJobEpzOEZtQVJodVZYVW9o?= =?utf-8?B?NWV2S0t4Q3ZZRXoyV3JPd0tHcnFXalU2N1ZkZlZHRm1LTGIwTEVpcjlwcWp4?= =?utf-8?B?dkxGM25DREp4YVVTMlVNWU5zc05LNUN6RVFaZUtXRzAvT0ZuL21qYzRRbkNT?= =?utf-8?B?U3VxSDcwVFRHK3ozS29hVW5vdW1uTjVjc1RXbXBRbzRyR0dORkVyd0pWUHpB?= =?utf-8?B?UnFVZm9Za3d2dExkcWJFM2grTThtTGpDd0ZRV05tWVptY1NubklWUVdiQ2Vv?= =?utf-8?B?cnJwaEJLMGp4ZE11ZGlOK01JWlNLMTJRWldoWFU1eE03NVdtbG9pUStoOGRC?= =?utf-8?B?RXREdk54MEJwSzY1OVlCN1ZpQ2RidHh6OTV3ZXBZLzJNS3U2NVMyQk12Y0du?= =?utf-8?B?UG41QW1FYTh0YU5SdWRLK0JySko5a2VDcXMva0dPOG1EaWZjcHhsSGpWaG5R?= =?utf-8?B?eWg0b1cyQzY5NEVuVWNKYmtIT3RrMHJHMG9zTVF4K0x6dWRFMzlZU2NnMzRz?= =?utf-8?B?SUlaZWdPT1RIN0owellScUMxR3ZJRnhUTzY3YWxhcTl1VVpEc1U4NlA0M09V?= =?utf-8?B?UVY3WUN2c1NTWURIblgzQ3lvVzFlSUhudTRUKzJucGhHaW9ONTkrRkNUMlB5?= =?utf-8?B?TXVsdllLR3JpUDRTOVczUy9jV3IzTk1XUkh6MWZTeTdQZjZ5a1dBRXF2bk5t?= =?utf-8?Q?uJCz54mBlY+14a6nwO?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: dcf9bd2a-ba10-4971-8e84-08dea06c32a1 X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB5685.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2026 12:39:30.2082 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: H7vVzALxq15kQCMSBceabuoTU67W4blnLomOuTx3mzcYGc8B8Fpbn/gsWEX7hwGS X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB5594 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 4/22/26 13:53, Jason Gunthorpe wrote: > On Wed, Apr 22, 2026 at 10:17:06AM +0200, Christian König wrote: >> No, not even remotely. I clearly don't want such an interface in >> DMA-buf at all. >> >> You can do that as private iommufd interface, e.g. where iommufd >> offers the functionality to say give me PFNs if you want that. > > I'm not sure what a "private" interface means if VFIO and DRM/RDMA > drivers need to implement the exporter side? That's not exactly > private if it in so many drivers. > > I've tried to make the importer side private, if you have better ideas > how to make it more private please share them. > >> But when there is a DMA-buf interface even if it is limited to >> iommufd then others will want that as well and that is not something >> we should do again. > > You can say no, that's the point of the export symbol restriciton. > >> Even for iommufd I think we don't need that. What iommufd does is >> basically manipulating a specific IOMMU address space. So the >> interface should be to give that address space to DMA-buf and say >> hey please map you backing store at this address into this address >> space. > > Isn't that pretty much exactly what this series is? Aren't you > splitting hairs to say an "address space" requesting physical is OK > but a "mapping type" requesting physical is not? The net result is > exactly the same, physical addresess flow from exporter to importer. > To be clear, there is no way, nor should there be a way, to use the > DMA API to create a reliable dma_addr_t that is 1:1 with phys_addr_t. Mhm, that sounds like what I wanted to say wasn't understood. > Can you be more specific please, I still have no idea what you are > thinking in terms of an acceptable implementation. Let me try to describe it differently: The iommufd deals with iommu_domain structures which userspace can map different things into. So of hand I would say that an interface to map DMA-buf into such an iommu_domain should look something like this: dma_buf_map_attachment_iommu(struct dma_buf_attachment *attachment, struct iommu_domain *domain, unsigned long iova, unsigned long offset, size_t size, ...); The DMA buf exporter then maps the its data into the iommu_domain at iova starting with offset from within the buffer and size number of bytes. Regards, Christian. > > Jason