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Tue, 29 Apr 2025 14:46:26 -0700 Date: Tue, 29 Apr 2025 14:46:25 -0700 From: Nicolin Chen To: Pranjal Shrivastava CC: , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v2 13/22] iommufd: Add mmap interface Message-ID: References: <7be26560c604b0cbc2fd218997b97a47e4ed11ff.1745646960.git.nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF0000467F:EE_|DS0PR12MB8442:EE_ X-MS-Office365-Filtering-Correlation-Id: 034ec9ce-8a34-486c-6b16-08dd87675350 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|7416014|376014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?tg29d/oKrJE+6h35+T9B/08T2yz3PQS1BIv8xaO3lLrA/9S0jkkeBBg0FVmK?= =?us-ascii?Q?N0x2lUh78mjIoaNcftc2/npneWuASysj9z9xK/v1cixWW56NI1c5qLtmizX7?= =?us-ascii?Q?7xTuZzMLCT92Z86HwsA7vhHfeA5bQCbKi2FZgZ77snrwY4OfsxPpahax+gTi?= =?us-ascii?Q?i0j+ZHoyavfz493v9k0Q0Yj1c9//Fms15AlNZVZO1pWgJlJ7b4ZonF+T6VWa?= =?us-ascii?Q?CMl7krOYpXJBtOK+li0jyXzxwJoDJpy6UxP8eK9/nct2AoCfXe6oK4c9AtFs?= =?us-ascii?Q?g7V7ITx81kywvLCNstOJAKbQB1gHGvm/IWoQbnCcDvQvyqjrNxNPBEi8+J4e?= =?us-ascii?Q?0op+gjtAC/MBbv4Dbe1Pe1WWDhqDDZRu/OR6IH4PhEoVrZid7t4I32fWoGhq?= =?us-ascii?Q?dwnKfSUfxstbTJltCJS4WD+6/JQYgMKjZ3D6p68i3Ok0bmv6m38Wq+a0BaD+?= =?us-ascii?Q?0k/fC5rykEGNZKCZHUe3FM9NvJcd6V87ksaNEo+020T0er8hIKDARN8JeqbF?= =?us-ascii?Q?dsyzSnRY3Q2amlRW6Nf5zcZTFC+dHlJJLs8GjqS/8M/c1q2NqoRje+ULro20?= =?us-ascii?Q?QXA0c6NdstQWcRztPsFyqdEuku+mz4Z//AjEY8zzN8rfiU+SRVcbWsdCW46u?= =?us-ascii?Q?pyQJU3xPl3geyfFIxRn0jKek9DPFSrBnd2lgii3f4pc1gcEWW4HbADEBzqAs?= =?us-ascii?Q?N8ITQabQz4i0u03dFaj4j856r+ddLjymbXOmlFEop6MH51hl1HqXxMbZ7oTe?= =?us-ascii?Q?70p+yk0tHgQQsvdf3triOie9Ergxg8SAqXMwz8ZYFYXu5O6YG3BGlZKDPTyj?= =?us-ascii?Q?F7UTugaefHnOPyG9rsXNLF0qERUyQeNXSGLxdL3UCc0qEJ2SAmSb1RCEq/qZ?= =?us-ascii?Q?gudilKhxdY8hgiVUVWQIc+dFtkIld+uHRaB2u9atr3YNk8HmeyxAU+XXNBP6?= =?us-ascii?Q?KejqUyHoHSXK1hYUfJolS4lr5MPo1JaTUxqT1PIU4e+3c3VZ1dciK+hqSx3P?= =?us-ascii?Q?EyH6h6RDdsirFQBvnpD/VgE3iYxIOiA2Oq+he4b1Ho+QfL9xaBOwVTd4wemF?= =?us-ascii?Q?MHJxwNYJHEOm2yvuUY/afuqnHVxY6M0zp265tFGSLfCDe4RAcCu2TIowy23s?= =?us-ascii?Q?UmwLdr2vl7Hxxke3SjaHdADJ9I1eFD587fVwHmJwIyEDPnBQkRCswqAygf4S?= =?us-ascii?Q?YLB5e4JMrdIjLsYo/Hje81YdU54nuIGQYQMZ20mE93bUsA9WUdWVJ47QP21d?= =?us-ascii?Q?o+ROXik1XbIm8UGLwwDpjFoeEjtm0Imesijd3CRi1hY0NpUeA4IBJKyjeKLN?= =?us-ascii?Q?roWb51rEJlCfroE4DazKfqbjoJTkcK+hYEwRmhLZq6QihBjURxvKhMZdCRr0?= =?us-ascii?Q?uHVNhteRfzDarTe3HzcL7Mh1PflZifFcHD4MuY7OgQ7RV2Q5Q1VX+YBFxuVB?= =?us-ascii?Q?WCn/oaa9qjqkrIlPhoKdMVUQTNxkG+WLW3NidDtuOKnczOzG21xpNn+ziGZ1?= =?us-ascii?Q?b90Q2Zfuz3dVjK91dOtyxF+qNmizmLuRYkiC?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(82310400026)(7416014)(376014)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Apr 2025 21:46:40.3654 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 034ec9ce-8a34-486c-6b16-08dd87675350 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN1PEPF0000467F.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8442 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250429_144648_795826_4CC7E1DC X-CRM114-Status: GOOD ( 23.20 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Apr 29, 2025 at 09:35:07PM +0000, Pranjal Shrivastava wrote: > On Tue, Apr 29, 2025 at 02:05:12PM -0700, Nicolin Chen wrote: > > On Tue, Apr 29, 2025 at 08:55:47PM +0000, Pranjal Shrivastava wrote: > > > On Tue, Apr 29, 2025 at 01:39:09PM -0700, Nicolin Chen wrote: > > > > On Tue, Apr 29, 2025 at 08:34:56PM +0000, Pranjal Shrivastava wrote: > > > > > On Tue, Apr 29, 2025 at 08:24:33PM +0000, Pranjal Shrivastava wrote: > > > > > > On Fri, Apr 25, 2025 at 10:58:08PM -0700, Nicolin Chen wrote: > > > > > > > + struct iommufd_mmap *immap; > > > > > > > + int rc; > > > > > > > + > > > > > > > + if (WARN_ON_ONCE(!immap_id)) > > > > > > > + return -EINVAL; > > > > > > > + if (base & ~PAGE_MASK) > > > > > > > + return -EINVAL; > > > > > > > + if (!size || size & ~PAGE_MASK) > > > > > > > + return -EINVAL; > > > > > > > + > > > > > > > + immap = kzalloc(sizeof(*immap), GFP_KERNEL); > > > > > > > + if (!immap) > > > > > > > + return -ENOMEM; > > > > > > > + immap->pfn_start = base >> PAGE_SHIFT; > > > > > > > + immap->pfn_end = immap->pfn_start + (size >> PAGE_SHIFT) - 1; > > > > > > > + > > > > > > > + rc = mtree_alloc_range(&ictx->mt_mmap, immap_id, immap, sizeof(immap), > > > > > > > > > > > > I believe this should be sizeof(*immap) ? > > > > > > > > > > Ugh, Sorry, shouldn't this be size >> PAGE_SHIFT (num_indices to alloc) ? > > > > > > > > mtree_load() returns a "struct iommufd_map *" pointer. > > > > > > I'm not talking about mtree_load. I meant mtree_alloc_range takes in a > > > "size" parameter, which is being passed as sizeof(imap) in this patch. > > > IIUC, the mtree_alloc_range, via mas_empty_area, gets a range that is > > > sufficient for the given "size". > > > > > > Now in this case, "size" would be the no. of pfns which are mmap-able. > > > By passing sizeof(immap), we're simply reserving sizeof(ptr) i.e. 8 pfns > > > for a 64-bit machine. Whereas we really, just want to reserve a range > > > for size >> PAGE_SHIFT pfns. > > > > But we are not storing pfns but the immap pointer.. > > Ohh... so we are storing the raw pointer in the mtree.. I got confused > with the `LONG_MAX >> PAGE_SHIFT`.. Sorry about the confusion! Yes. We want the pointer at mtree_load(). The pfn range is for validation after mtree_load(). And we are likely to stuff more bits into the immap structure for other verifications. Thanks Nicolin