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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?mhMAziScQhH8KCQStXlTmFBdDij5GK+OSQQUD4jDgc/QkjA5nX8fN0vEJrfc?= =?us-ascii?Q?AcuVIkBch8zR89JUvwqqkpT+p3azA0gKAxAHw7jGqRh+1RdZV+IwN7nv3itq?= =?us-ascii?Q?hofh60ZZC27dmWo3yaIhNx0DuykPAHihIs4LS1ia9V7xbCfXWtWQ4jn/8kHU?= =?us-ascii?Q?ILCQjM4xONMENShfUVnx5Bfg+OdQGGS3wxFq8U39bvoYHZCLQ+vyJsaZonsN?= =?us-ascii?Q?CSF2eacdzTXKvi/AeF/Y0q4irL/5f5Y1b/OGJ/+VuvJeD8I7bvbchD47+w2t?= =?us-ascii?Q?HwU2cL8/QT/aatKtD+six9OC77Cmy41jpaWcvrtZRJlq/zt8HHCpixbNrflW?= =?us-ascii?Q?ejhP25UTjUnBv95uI2AH0AH/GPZUWkvd/11rlTMSSpCGPnI91bX52iJ4eZuY?= =?us-ascii?Q?QUKqdaYKsBVpZK1Yn1WP2WSrVy4Bh2l8aF0SM6Ans0uJMP3LgFoCVJ4TC4qW?= =?us-ascii?Q?b/88k7h7vN9vfrk1p11rPH8I02BwqCJJR/8OxQazSLS5i11iBq5G7z1iSzyg?= =?us-ascii?Q?OSoD3u8eeGNbm1zLO0lPRikyM3VQiO4BKPhl+gQDTbOm2MvHTsfDgfLIO9ec?= =?us-ascii?Q?qOFCCIc5FJHqna/1UQpDELKiIaXZ7pZ0iPg+tMbwNeJAj/6tu/jbmbCYdFXV?= =?us-ascii?Q?EQs7cNC3qzK/YHwzHlwmkgeIlMvTkTDcX0yxVyeH+eMKslOOzXIDCtLaN+g3?= =?us-ascii?Q?I6J98BtaiemkBYxrKNwxuk8Yx8P6ThrBCOu0G+mLBI1EDv7SOXaMPPY9Agb4?= =?us-ascii?Q?K2xtlVZlmcc3VqphV7C14kqHMW42m1jG0PKVZp5XUjM/On2KPBIk/ovLD8Ta?= =?us-ascii?Q?VKNdshZd6k6WMZEcBDcZdoHGuTLhqSS9NG1tydwYcJtIBvSeD6Sn2ALKyeCQ?= =?us-ascii?Q?9ZWD/C7Gim8O1OEX9QGS4z21bdq7gp7edyj3OzJO6DwL0Wh8lYG8NmgmaiFa?= =?us-ascii?Q?zpIJUleJ7vxt4vaUkcdxni4NK9suxrXf06sp8iHYWo7QLMKRO51USRmVB5+h?= =?us-ascii?Q?HQuZdtyU/lBJuWMuUr2bYGxWYscSlB+z2Qofyi0pSv9LWxkuhr620y+xIv/S?= =?us-ascii?Q?u05c2LG/aFyb7aO+w7C5DlZUMHzrgWUmEm6Z8x6Z2/3B3yTIf7YopU3hqFF3?= =?us-ascii?Q?UvVelO0CP+clJCf76cSnh6xxfTgQr02gV3vJXCeNdRCp44xAWALkf3DhWDOz?= =?us-ascii?Q?DQsjfbfONDQI0ExZMwPV0shsmR3bj+qPoF0Y2y97UbsaTfwenoZJQjNlN4xx?= =?us-ascii?Q?gxIcgLq0eYkRj2Sx/5A1SoiCaWV94VKIJfIEPhjpbspAFntYcotvh67yeRJP?= =?us-ascii?Q?OYt62cwY/sKnI9RLtQlGYnQ6GDaOV3dD1jFgmfpwiaVwhOF35COm+NYSr4vL?= =?us-ascii?Q?JiakGZnX/SldOJgzefo9O8a9W7e4sEBKPRhta3c2HCzDUZ/2EHyw3BJKeofi?= =?us-ascii?Q?ySIdXIWPkPwonw5Lok6oWrWpiKAI6PeHyLslp3Wk4LKY7CXWLUqy4vGmM+9/?= =?us-ascii?Q?jMnCpyciRliiaQRF2rjYg+W5Yv0SXlc08UdjtHoC3XTe4BBYMdSCvQKnGLob?= =?us-ascii?Q?r8mklC3eFbv/VuZBooJhl9RWhzicWX6amG8stdDQ?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 08c97a9f-9d49-4405-87b3-08dbbde5c22c X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Sep 2023 16:37:50.7461 (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: C8AJpOapC7Ei+ybImVyyS3BdWC5J/xEzjbhtFGvmdJfdCjqWB/7awIhCRmHXpHdF X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB6824 On Mon, Sep 25, 2023 at 04:31:50PM +0000, Deucher, Alexander wrote: > > On 9/22/2023 5:30 PM, Jason Gunthorpe wrote: > > > On Fri, Sep 22, 2023 at 02:22:11PM +0530, Vasant Hegde wrote: > > >>> 2) PCI device supports ATS and PASID > > >>> In this case, ATS is required for PRI, so we should enable it > > >>> even if > > >>> the default domain has been configured to PASSTHROUGH mode. > > >> > > >> IMO we should enable ATS along with enable_feature(PRI). > > > > > > Definately not. ATS is valuable and importnat without PRI. > > > > I get that. But I am not sure whether I understood the usecase when domain is > > in passthrough mode. Do you have any usecase to enable ATS when device is > > in pass through mode? > > It should still reduce latency. Even in 1:1 mode, there is still an > address lookup that can be cached. Oh, on a lot of devices the ATS bits just enable device's PCI to issue ATS, it doesn't mean that *every* operation has to be ATS. So the non-SVA transactions can freely run in non-ATS mode with 1:1 while only SVA operations use ATS. IIRC most IOMMU still have a lookup for a translated request to validate that the RID is authorized to use them. So there is no savings, just overhead. Jason