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Thu, 15 May 2025 13:32:49 -0700 Date: Thu, 15 May 2025 13:32:48 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v4 11/23] iommufd/viommu: Add IOMMUFD_CMD_HW_QUEUE_ALLOC ioctl Message-ID: References: <20250515160620.GJ382960@nvidia.com> <20250515185938.GT382960@nvidia.com> Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250515185938.GT382960@nvidia.com> X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN1PEPF00036F3D:EE_|SJ5PPF4C62B9E70:EE_ X-MS-Office365-Filtering-Correlation-Id: 657e53f2-0f3e-49c3-8b2b-08dd93efb015 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|1800799024|376014|7416014|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?9MgOS03szYgiRVtPFcfgqGXhkUajnTm422UtNCgDAkfaoU+I1kAQQkuk/ChU?= =?us-ascii?Q?ev8IH8sQHB/mGzhJ3d8ZZ7qOgBKIsIgvvoS7WawRYadrtptGxc53oGrS9x2x?= =?us-ascii?Q?xTMLdHUo8S14x3zsQLhn5s21fZyXBbfNbDSVg+WCO/U5P9AFhiiVeyKBB26L?= =?us-ascii?Q?UZNLMXNwLTN9V8YuJW6YE9KVyyP4Zi7Vr9tVbQ40x/WeUfIba29SoA/WhZIk?= =?us-ascii?Q?6qc2sx+3K2U57iRIZgYyYg5cflRbd6WdeI7kWQHlImGZ7IjFdaZjhKKK4/d3?= =?us-ascii?Q?c0SEE6hShKA3POYO0+Tsi536w6P0pvgOLcQR1weKz75+565PLh8p0r3kZ4wa?= =?us-ascii?Q?ttsHyB/nExf36Bg9SjRgk3OJHLUSy+Esur2gKf5xisAl/jU671Jg3GGZzJEX?= =?us-ascii?Q?P5ussSjxIORCzrKF7rRtvEh31RY8BbkliGcDTCXOX54zNBjBpYgDJiZQrsfl?= =?us-ascii?Q?oqZbUVScBMeMwp3qdz5K4bK9PQ2t454R5Sr76n5oZ0apAS75eelsoAa9P12I?= =?us-ascii?Q?MOcan+4z0lWvUw7MlYisA9wGdogJoD1mp2xQMe4G75vb2VugbVakJ8j0yns4?= =?us-ascii?Q?lpYACI7TGQzZD7Adbrveri1PlXCcxdjuIqvrf1Bm3mZ8jP8IoC6Ra877dSFD?= =?us-ascii?Q?nZbsrERTNM73kkTVfAFnTYSDWISxkNHsL6TGljwYTvWLQjLg+n0Y6zblw2sl?= =?us-ascii?Q?77nmFTz3UW8NDEKDIeH5v2a5FXvtwopkFb+HACkhiFW0QqDKFEiwhl3S0AZM?= =?us-ascii?Q?gnFPzMXdbUlXQKP1crZFSrFR8mfGtoYRnPFrLvv21hs3Z50EnYjiVmYrK1QC?= =?us-ascii?Q?LCbLHbJVB2zfuuCa6l+2WV4J0KiujfhcDQV/LMDTC7GMSYW+SIN1JMtkBJFk?= =?us-ascii?Q?NKxcL2uoKvVBPz4xS+gxkYow967QynH5ZzzytpvClA1OSRg2kCFaNw1uoJX8?= =?us-ascii?Q?QmioAsRWImeR1mjCx4YYfID3qTNMgh+hfC90TQh0yip9yhdy1dfShICOEBVl?= =?us-ascii?Q?6VgMEMeS7ZCCEgn+0q4aKfFinKwb/QspzW4nHjkLKLqyXGl8fU+FuI9u6nAR?= =?us-ascii?Q?ODyEFDCAxsf5zqr7Jtmdbb0OIyKOIaCLqyNdqYgs3RMfSbbmioQMVAdzNwxh?= =?us-ascii?Q?cM36Yt1x7Sur9gOMdqQY+p0Vy1f7W2FQiVLfYBNk0yydTXLk0hlWnreUsoXa?= =?us-ascii?Q?6aHsqN3xbyoevud9A5n4nytv7czErx0RLJe3fDkjMUt2I8fg0vk7IMfxZ9DE?= =?us-ascii?Q?op+eyMi2bZl2BIxYhte95ulFs1F96mzLplURDHNegHQWqQABjXkgd5QqHWVF?= =?us-ascii?Q?E4j3Rq03bgdjbyNiaJo+/AKCq81Bz8BtPM/i5dHhBPFaYpEoFnPAS0nkl5Cq?= =?us-ascii?Q?DhUI6ZfWHuh+vk3ew2hiSIu0QCR5a5MBoICpZ6Lb0hGMcLfE9xXPv+NApAiy?= =?us-ascii?Q?hpgcwEmOs+Un07DtUYMmUvKU3483sDzfTpzBmbv6ZX9DZEdpzLeE1IE4tz0J?= =?us-ascii?Q?Uwrk5e9yHxDzOlHSUxuFinM3x0GI6GQeicky?= X-Forefront-Antispam-Report: CIP:216.228.118.232;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge1.nvidia.com;CAT:NONE;SFS:(13230040)(82310400026)(1800799024)(376014)(7416014)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 May 2025 20:33:01.6083 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 657e53f2-0f3e-49c3-8b2b-08dd93efb015 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF00036F3D.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ5PPF4C62B9E70 On Thu, May 15, 2025 at 03:59:38PM -0300, Jason Gunthorpe wrote: > On Thu, May 15, 2025 at 11:16:45AM -0700, Nicolin Chen wrote: > > > I don't think this actually works like this without an unmap > > > callback. unmap will break: > > > > > > iommufd_access_notify_unmap(iopt, area_first, length); > > > /* Something is not responding to unmap requests. */ > > > tries++; > > > if (WARN_ON(tries > 100)) > > > return -EDEADLOCK; > > > > > > If it can't shoot down the pinning. > > > > Hmm, I thought we want the unmap to fail until VMM releases the HW > > QUEUE first? In what case, does VMM wants to unmap while holding > > the queue pages? > > Well, if that is what we want to do then this needs to be revised > somehow.. Yea, unless we have a strong reason to allow unmap while holding the HW queue. I think we could set a new flag: enum { IOMMUFD_ACCESS_RW_READ = 0, IOMMUFD_ACCESS_RW_WRITE = 1 << 0, /* Set if the caller is in a kthread then rw will use kthread_use_mm() */ IOMMUFD_ACCESS_RW_KTHREAD = 1 << 1, + IOMMUFD_ACCESS_NO_UNMAP = 1 << 3, /* Only for use by selftest */ __IOMMUFD_ACCESS_RW_SLOW_PATH = 1 << 2, }; and reject iopt_unmap_iova_range(). Thanks Nicolin