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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?w5UxRcPTGasYxFxGRqK7CSQADf1C9skfwpMwvK6fBo3tHGBjB8HsXJ7viBzC?= =?us-ascii?Q?Bn7DL+8bbzB3yxh4ecZhpym0LH9ujlmNgU9ne8iTpfUzmTLwo6sM7FdpfOnb?= =?us-ascii?Q?V8JFzuVeexglj4R/N18gkTKOJr0rrbkgaG9Yvm9VRdlR38sPugi9Nemc9UCz?= =?us-ascii?Q?Zc6ueM5LRYq1YhGDVmEVSQvyRz8CrJwgapkv/mbyj4spfiEkHMns0MoreOL1?= =?us-ascii?Q?503B5KyBSNHQbFLnQIY+CAyJUufUEr4npYahXlKxjZbxcFtJqyVCpMOMqzlk?= =?us-ascii?Q?YX5mCYfREwyk2WpC3TAjLJY47Px32qC2i4+fhEjrO3En68qULtRGLsvEOJN3?= =?us-ascii?Q?g9QlbmGY4vvRgfPCP5SH/P+W/A94SegmMBOIMoRJQUIaqa36tJ8PnM9bF22v?= =?us-ascii?Q?qDM1zG2vUzCgGGzNV+oEuyoR5e8eYHBIHZmtRF3JEmDrNdXkjoNX9f9LkRQN?= =?us-ascii?Q?LSEYKDqb6Oe1RYNIOICVlu69GmbV47MU+rKRzKk0Q0/Q5yodFTfYVkqS/5T5?= =?us-ascii?Q?Uj4UXynUpsJH2C0SoiR8m6TFpy6Ljtm9RtLwT3afiIf1t3oLUhzcksXEQhMt?= =?us-ascii?Q?zGQlKV4VZLC8AT+DZeRhHNog4+fYD6rE3qg89hZG5wbRyt91EuIbw9L9Kk/W?= =?us-ascii?Q?dBsjEccuUffdBGlPfFWE+jEDV1cd2t5Ot7Z00NOuonN9JQfJmnUUUf4lzq6O?= =?us-ascii?Q?0WX+a29PuNBmsAI5OWaxHq21tOFDzda1dLk/w/m6zzTvsDi9uHYDxsGZc86u?= =?us-ascii?Q?kPqHziHpkYrdRjbhqBAJvrXnDeRz8GughPXfFkz71cLkYMfMp2ciG1f6cVwg?= =?us-ascii?Q?EESwx9y7vvUPqenxXYUFReWBVLd4gGDKPKqrr8QTWVfMNlBH2DsvKIq70G09?= =?us-ascii?Q?VH0PUtHFmANdqVxCJ/XbAv0bNXaZQAii5qYQa+v3ZPNgiEscbJ06lJKP6sMo?= =?us-ascii?Q?fxdLmYJIJmHADlivQOEjrFoKoUuBETW1qty/kCE4fPMn6PgNZoN1RZYuK/DA?= =?us-ascii?Q?rSV1tuZH0s19vFJ/TKMlqNYQyz0Gb2m5QhNzzl9Krz4L9NJBGAcaagf5c/MK?= =?us-ascii?Q?ZyXRmTnHLtzrjWStVxg6DBjX+vyG0EcifTMzbGdZ3Chf8D7KCZjHKQHsvtGY?= =?us-ascii?Q?DpxAb1Ou1BL/etUox8g8s82yWa/R7w8ig3MySXJIOoDT8fwjjJLwc7mYa/ek?= =?us-ascii?Q?utiaXRj62xRaF1D4rXQdApd1ta8VDlKXKwM8bDbBSAVBWVa2Y1dar6Z/FuDs?= =?us-ascii?Q?SX4XbnEtuMSGyxWIitsGs2CwFoTjIVw7WQldv45Mh0sqfYxCzjfpz183FUgR?= =?us-ascii?Q?zWXX9wTmc5Q/9557BD8r/qzPRiZJttC128jCohi7+knefJWKrltQ3MoUo0lf?= =?us-ascii?Q?/pgZuJT4yu++pZYsTGofe12THydh+Sur2vyOjwQzeEce4wuqleYEvr52ahE2?= =?us-ascii?Q?9Dd/Q3uQCP/eGLpQK23p7Q2wPe7nwiN5ogZhMaqiZz+FTXGtciddrtH/KZZw?= =?us-ascii?Q?83qRAO5yh0ZofNRZxrO1moUFLz3GI53A5PIZletdyyzxnlo7vCTcoRotYfBO?= =?us-ascii?Q?2mrPVWmrX509Bv/c3hA=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 73c045c8-947b-4ed8-6b6d-08da6e4b9200 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jul 2022 14:40:07.9325 (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: FMMc6Vh8ZcqxxALNHHBNdbWGWHArReQP4RAkEzVvepx3NOGSLMFOyrxm7T77XGAi X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR12MB2900 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 24, 2022 at 03:03:16PM +0800, Baolu Lu wrote: > How about rephrasing this part of commit message like below: > > Some buses, like PCI, route packets without considering the PASID value. > Thus a DMA target address with PASID might be treated as P2P if the > address falls into the MMIO BAR of other devices in the group. To make > things simple, these interfaces only apply to devices belonging to the > singleton groups. > Considering that the PCI bus supports hot-plug, even a device boots with > a singleton group, a later hot-added device is still possible to share > the group, which breaks the singleton group assumption. In order to > avoid this situation, this interface requires that the ACS is enabled on > all devices on the path from the device to the host-PCI bridge. But ACS directly fixes the routing issue above This entire explanation can be recast as saying we block PASID attachment in all cases where the PCI fabric is routing based on address. ACS disables that. Not sure it even has anything to do with hotplug or singleton?? Jason