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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?DjSWR7cyFSn5g9DswKoP8QiIbCwnzPor+4i4yeBgK3IfEg1Ge0jVhw2w4jtO?= =?us-ascii?Q?5+c37BrCFBB6cxRrj2vVfKzifo9lhTLw9kzWYhTSldfYvLIBEVsKPvbyS/wM?= =?us-ascii?Q?q97cvuajLV2nCsXd00IQke313WHEeLTM54EOvY3KdzcaqF/P7OAWp8aqrRgM?= =?us-ascii?Q?QfBJHVg/+1z73Qnel3LyE/tTa2e7LVQc1jFCAdtEkIhHEhr5avdHmzVgVsoL?= =?us-ascii?Q?ljCtIBP/sYbmSBxPLDvy+hnF8NyGtgLXVRmw9c9EladTG1Xnh9PR13sb7NLF?= =?us-ascii?Q?75OzOJykBq8jTesvFqrT/dw5E095ANsvgEywdX3aPVg32KuwRWW39TJT7OxA?= =?us-ascii?Q?SyU8E13hN9NZlwOgXKhUPs0tPihHTeKnuH7fVwMzyXYpmtbOLBypk6BbY9+P?= =?us-ascii?Q?8WJyb9cMPd3Qq/++09NB9U1h9J+xSRf67E/AOEYk2e8BJ5/0UDzOsMZBzV1/?= =?us-ascii?Q?89j0JNb3Yt/OEbUq89/i/k6LoBEel4HYon65hz1gt04Jn4WGHd5PJT/LdT5k?= =?us-ascii?Q?oHAcQxzgysx+CkVvKhWFS4xt6K0SUoywBWL3ovVGBbpb681KUXghaAjjGq3P?= =?us-ascii?Q?z8zsXbMkNs2Fsn6Y+FG7s0X7uIvw4MS8bxK1qTzoJ1BVOwPMNOTH0xJ1pylH?= =?us-ascii?Q?rry1+jeHaFAAWvDI6/s7snO3+UOhsR9dUYInCvKeZyEehchM6GMeRc8yaGKl?= =?us-ascii?Q?YXaVluVUMEB83BTQBKa+tlq/ziOhQ1U8jEGLc8wUIE7joNMqslytfnhygdcn?= =?us-ascii?Q?j+9zAKk3EuRlpHCz6cJ24WGrUXvE18jaKjJJjqPa+oed54lQkqnEWNTSrfur?= =?us-ascii?Q?kktVo1e1nZpU7ObuHPOBPWwJ5p9kQedn7X8Pn17UBj7xURJ3+G4UtYXnb3Dh?= =?us-ascii?Q?iNFIb9LZsK/LX9sV7IIRUIxfsvZPDUsyWMpIYME7aVa+775z0LKAskxW6Dq6?= =?us-ascii?Q?8av6CSKK1Grh+be9rjiBRPWMaXOGhf9yMWRlSBYl68SnCP/WqoGVu/B9+WLv?= =?us-ascii?Q?ztq2VZLmC7joqveDGHFBbvRoY6iMyyMW2CWhrYu8/44z4sqODmHP2rBbGhOH?= =?us-ascii?Q?BBLrffydR2QxK/KlpxJkmeOaODv+Ucia6R0rKU4IlmNAUZMuSdnGbw3UhQKJ?= =?us-ascii?Q?+L6A3Mlpsf3PNtJQUBjO+STqweQ3ziLlPXyzn2xnARen0U+u7RlUcgC4vVUd?= =?us-ascii?Q?rRmHN7zWrmGFkJVSeDwdwHzsHzCLylFgrM2W2DZx9KI7Svw/o9iwHbL+Rmhv?= =?us-ascii?Q?QwL/Yj8m2e1cWxhE3xesxVFVam2N2q/TtV/NZHOUJQYwplzNSyEETKyXSw7z?= =?us-ascii?Q?HpMZfX8yzC6MgnNCYGfNxsKB1wmT4d9/p4B7dpzPBdYSgNilkJxcgSA6Tt29?= =?us-ascii?Q?iyuCfh9wBK5klk0HRkgXclbKXY0u/XZ/Dg8D642GRSoanXaXGBu8OVdHNVLM?= =?us-ascii?Q?pXGy553NR6+W4BJJd+yyRb1YeubYhU/fNuYn6QWYu1/4XfeQao5VpoH8tkNH?= =?us-ascii?Q?9UGxpfyRTKydf/AVY9e8OFnbcyaL58qWoWtjgB409sIzs3BYIZu9r42mek1g?= =?us-ascii?Q?nBcUFWuKJszVevwCP3U=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: dd6cee00-3bc4-4408-795e-08d9ab5bfb41 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Nov 2021 12:56:19.7163 (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: ks5v0pHJEgPqffsZbUd5t3hZDDeIxU/Jzb/Js1pqKaF+zcJ4h4jTuagCPcpLpqBk X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5317 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Nov 19, 2021 at 05:44:35AM +0000, Tian, Kevin wrote: > Well, the difference is just in literal. I don't know the background > why the existing iommu_attach_device() users want to do it this > way. But given the condition in iommu_attach_device() it could > in theory imply some unknown hardware-level side effect which > may break the desired functionality once the group size grows > beyond singleton. Is it a real case? I don't know... No, this must not be. Any device can have VFIO attached to it, and VFIO does the equivalent of iommu_attach_device(). We cannot have "unknown hardware-level side effects" to changing the domain's of multi device groups and also have working VFIO. If these HW problems exist they are a seperate issue and the iommu core should flag such groups as being unable to change their domains at all. Jason