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dkim=none (message not signed) header.d=none;intel.com; dmarc=none action=none header.from=nvidia.com; Received: from BL0PR12MB5506.namprd12.prod.outlook.com (2603:10b6:208:1cb::22) by BL1PR12MB5253.namprd12.prod.outlook.com (2603:10b6:208:30b::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4544.14; Wed, 29 Sep 2021 12:59:04 +0000 Received: from BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::e8af:232:915e:2f95]) by BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::e8af:232:915e:2f95%8]) with mapi id 15.20.4566.015; Wed, 29 Sep 2021 12:59:04 +0000 Date: Wed, 29 Sep 2021 09:59:02 -0300 From: Jason Gunthorpe To: "Tian, Kevin" Cc: Lu Baolu , "Liu, Yi L" , "alex.williamson@redhat.com" , "hch@lst.de" , "jasowang@redhat.com" , "joro@8bytes.org" , "jean-philippe@linaro.org" , "parav@mellanox.com" , "lkml@metux.net" , "pbonzini@redhat.com" , "lushenming@huawei.com" , "eric.auger@redhat.com" , "corbet@lwn.net" , "Raj, Ashok" , "yi.l.liu@linux.intel.com" , "Tian, Jun J" , "Wu, Hao" , "Jiang, Dave" , "jacob.jun.pan@linux.intel.com" , "kwankhede@nvidia.com" , "robin.murphy@arm.com" , "kvm@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "dwmw2@infradead.org" , "linux-kernel@vger.kernel.org" , "david@gibson.dropbear.id.au" , "nicolinc@nvidia.com" Subject: Re: [RFC 06/20] iommu: Add iommu_device_init[exit]_user_dma interfaces Message-ID: <20210929125902.GU964074@nvidia.com> References: <20210921170943.GS327412@nvidia.com> <20210922123931.GI327412@nvidia.com> <20210927150928.GA1517957@nvidia.com> <20210928115751.GK964074@nvidia.com> <9a314095-3db9-30fc-2ed9-4e46d385036d@linux.intel.com> <20210928140712.GL964074@nvidia.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?5raLo0W1Pd7fZRL4loGsBZq034LNiB/MKI9QQf+JnhonTiUodoHJC7za/8C2?= =?us-ascii?Q?aT/o9NQa4r5qdlMmiTH7N7dOBNJX8W3JALSFi2makB5GZqkwjND5gAyu+I0Q?= =?us-ascii?Q?ZOsMDsy3/XFvKRXsJ1dUjoN2YskV4lBYkXDGPUihm0oBFeSaj1W5Qdrsuu17?= =?us-ascii?Q?3+uodyUkIRVwTZ4fURZZmr6WtABy9rRtmxcGYZkb7lRhbSDQwemi/uuwFA7H?= =?us-ascii?Q?rr15jn1X9NxmWkP81MWw8qCvXD9i+rO5B6rJt8V9q3bk4XGzqkjhFC9owK1G?= =?us-ascii?Q?sdiAASHp9St+U65v2ytHOJu7t8f06gKupkYqxf1VxBDNPtMb1o3BxVdKXNVg?= =?us-ascii?Q?cfO7O3Hj+LdCPp+RZ19TkgX2qER/Ck3XamS5VAnFUjdz768UjXzNEe+8k0LF?= =?us-ascii?Q?agyZ1ZlkifzKhYcgYAJF6loE4lRBqkXz/3ddnsxdNJsr4J/CIx6ls5LjRUQ5?= =?us-ascii?Q?y+FGFe4qrQBK+eXNKcABmQfB5VBuOsSNcQP6RcaezHz09LugupDcQoIdMqQd?= =?us-ascii?Q?bAL7PMTq5uR50QOfP0ZIqYRDB8KZAsGiiBzcODpLVzZOadZ72jiBxNwwWM9c?= =?us-ascii?Q?Q/pxBTImKSmDsonT/tpFNA2sZPn7t0q80NEOlsj7jCmBnmHYujDeXkRMmY+J?= =?us-ascii?Q?WQ9Skre4rQa/RV2dyCQ+HyCKaLyhLvKfHRCmVFPY9VTywy+DZGIs7i/kCeqA?= =?us-ascii?Q?S/xbCyo9Rb4wGuP+rGy1pPAAyDkxHTYW7oBF2feBIYEIdubPxu0QWxH5Xjpm?= =?us-ascii?Q?UlMPctZ3NHsKsHtuCHn6Trb50TM0nYakLeZN9oi6bZhpcToAGtRvD9kTM/lM?= =?us-ascii?Q?MIghdIXROcAHAgvPsUzoZAJLy3FVFQT++CC8Rqlk1geT3RSsO8TUxXHkrZhf?= =?us-ascii?Q?4+OpULcchf4ugh2b/eIekbBSjACBzfWRNXCkpAamJ5BlByMzkvI+ykuzMuA4?= =?us-ascii?Q?oAcnNRTweQQ1umhLaWUIUsIFdWti6pen6J5guVeSFYxTvYige911fsBu35sY?= =?us-ascii?Q?/G2x2uUJAjFZb9tqu3Zogb3EnAPkI6CEtvgxVS3w47G0eoGh7B7woPLSLN9+?= =?us-ascii?Q?Kkh1ac3F0JAyACaEjB1TKa2TinnEYSFiumj2Y7BA6+viPogxgVEgZDkkDX2O?= =?us-ascii?Q?bydKAPvj+FSKc0lvvLCJgfXD+6nCkICosEuMf8Osgt6rBl1zzOC1YVhy1ibF?= =?us-ascii?Q?iN7gDlCMT2N6Zb3qF2vbUFTmmhTOn3OZe1Xobd/xU8XaHQg4pVV4yhaG+jDW?= =?us-ascii?Q?157Yc7wt1aiItM6iWKlIrdFvtNJtcObpt6BZoIXQt8X5mZU0zHgZjrDEXhYg?= =?us-ascii?Q?JxWvkElsNm1tyPzLVTeoFfbi?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: acbdf931-b317-4e2b-dc8d-08d98348ea01 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Sep 2021 12:59:04.0413 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: gNKYRU2S6iMdGYfvdF5RdjcprGiZKUeUgh3Otv+2entbqLqdlo1soOLY5fJBZ88D X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5253 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 29, 2021 at 12:38:35AM +0000, Tian, Kevin wrote: > /* If set the driver must call iommu_XX as the first action in probe() or > * before it attempts to do DMA > */ > bool suppress_dma_owner:1; It is not "attempts to do DMA" but more "operates the physical device in any away" Not having ownership means another entity could be using user space DMA to manipulate the device state and attack the integrity of the kernel's programming of the device. Jason