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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?qXeCQs2O3xl8b8YMNK5Lf8TDV+AtJPgwXV2pepxdoCygU/jJFP/xhKkk1Zwy?= =?us-ascii?Q?3Wv1KB0skzPFpdukaDlI+Q0PRAFs5OXZeRMryXsDzCYSKHPUSPSkLvNhKo42?= =?us-ascii?Q?lcQkUXMzcwqqLUCQSfN7XRurWKOEH4Q38atmvHeh+VR8Qe4PwSmGPbW7HeiB?= =?us-ascii?Q?JEGaZmgRi15HqaZsh+54OnwpG26UAuN5vYMWLlgVgVBHAIjrcGh7SX589DUs?= =?us-ascii?Q?E9KSsSqP2CaOooxw38gL3WJLfu9xlqNu7AU656Dcs+i2EZnPdfc+pZSoCi6+?= =?us-ascii?Q?DOGHTBZik2ZBk1sFZTAhoI2kTRJTa/TupQVvZgI/nfJ7ghcSBG6yrBTm5y2Y?= =?us-ascii?Q?0ghpW0TdXgIQibcVdi1a5yhVVeH25oQ01XC5Zg4fqXc8V4Z44SEdF9NOyCJL?= =?us-ascii?Q?p182WcbFPGwl1Lfccb9qAe6wEAE5m2NsTUiH1IZOdI47eX2yDrpEo00i8avJ?= =?us-ascii?Q?GYjvVDvAhz5U1rHLeGSjotiMRAjQLlzGHx0paYxbnDVJPnY5MtZBk3LIS3QR?= =?us-ascii?Q?Xhbj9l5welCajONMUSr2c2uUT0VDHbNbIHCclFChOO56f0Dhpk9w7u4nNnTl?= =?us-ascii?Q?ICtVg7+tuAnGzA5aBvXskZu4wt49fQu6BAIYo0uu9JHO5JAx9dvcY60ZlI5e?= =?us-ascii?Q?OZ98B96ULDQ5t0Xeybl8ZLK4IesHVKFf0Glo51dZZKoROwi2KKLqJxdyofN3?= =?us-ascii?Q?sk1OsYcQKIstqc7dfHjrcItiikXzgRuLrmqYa3+AHrRUenSmNiAFBmaUwxcO?= =?us-ascii?Q?FpY2RBpydmGNFhpI4XApFpMpcwi9Wpi9IBTEU+4py1W4lbajsU0Mf7S051Ox?= =?us-ascii?Q?7AcAUtzj25KZLj4N6ZQfB5ZhqdqIRk7lQdl4wD2dBVtbx8omsfzeDvAVCMGN?= =?us-ascii?Q?X5av6fO1iDL8X4uDz/9RQVQJtqNaCDsVAXWnrK2p98FYa6WROt8Ddd6PbFnk?= =?us-ascii?Q?/vsDkQxLp4l3yc4EbZJzKu1OQWdDYbaowrmp35s6ASiwZaDQEgsenYKCqZVc?= =?us-ascii?Q?Chv3uXGmn8hK2UIty0xL4fub1gHdXnGmqzs08+iG8YlhLPDot6HM0aygvVyn?= =?us-ascii?Q?ULeB33wkoFtG2Gi7obqAmdMLjhKHtxYPLNC1smrQqtk2Y358wejPPDg6tCzV?= =?us-ascii?Q?+7vvhlsbtbfOkKJcX8RXOsb4A3QQZtK6qW4S6INEWElDXOmVeVzbORnGYEJN?= =?us-ascii?Q?9uRE8C5gNcuaQcUzjQ61VYgsw61zDXMXlpaF4JnE/1XlsCFaRKcKG4BZ0iu/?= =?us-ascii?Q?Q0dahoYHqBXRHlDepxK8muC3cbQdT5zBzcIAshB+z1jpJdwok0QrYXZ44yjv?= =?us-ascii?Q?3gfnCarCUWkmFezJroDsaXTKEag5fBQ9zbr9DiYmcktEysgks0m2/5PqCaHO?= =?us-ascii?Q?2JW9ghvc8Vxq4ucX8/mjpO8k2/BoCtzU4scZDUXENm12MULpsn6k7peCYNY4?= =?us-ascii?Q?w+yH06ofyNlp9BEYYav270q1X8RDmxUUFejZKKrEajthB87WWk7BZjWKbl+n?= =?us-ascii?Q?vzZOCf857juCS4df7/gljARbo0CRADRIFLxJXVesLzppIuFP8MvZecTwNB4U?= =?us-ascii?Q?VX/397sNoZRXFEScAhIp/P4SFK+nTP2T8igW4QwvhrXQNQ8HdLrjO2Un0LcF?= =?us-ascii?Q?az3gPsc0kbP6cWEdcLUslOXrgGBC9iTmhx3FO4vs5Q5JUV6SSQf6ybicOOtz?= =?us-ascii?Q?Z8SRVfbz6zIdNZ8ic96oPZKvfUgbNItKmmSvXEa4+wxp5qxV?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2272d622-5f5d-4320-be26-08defd839d04 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2026 23:51:25.1630 (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: CDdki0I7HNb8Cj7PVMDMr8i5mRfBlel+K/RLc9oEZo8Q70xufFSG/8iRd8UOVej+ X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8936 On Tue, Aug 18, 2026 at 02:01:19PM -0700, Jacob Pan wrote: > The rough flow looks like: > - vmm creates an iommufd ctx > - open cdev FD for the assigned device > - bind vfio cdev FD with iommufd > - vmm calls /dev/mshv or xen to create a partition, stores hv allocated > part_id in its vm FD's file private data > - vmm creates a per vm viommu ojbect of direct attach unique type > - in this hv-iommu-root driver's .viommu_init, fish out the part_id > from the vm file's private data then stores in hv-iommu's viommu > struct. > The rest is for direct domain attach, roughly > - allocate a vdevice under the direct type viommu > - allocate a direct type hwpt (new) > - attach the direct hwpt to the cdev, where this driver can intercept > in its direct domain callback (instead of abusing the paging domain > attach). > > With this flow, the VM identity is explicit through the vIOMMU UAPI > rather than inferred from current tgid. Yes, this seems broadly OK > One open naming question is whether "direct" is the right term for this > object type since it hints 1:1 mapping which it is not. It really is an > externally managed S2 domain/iopt, so "external" may describe the > semantics better, as Teddy called it in [1]. I also think direct is not a good name. External is not bad with something like 'external hypervisor controlled translation' as perhaps the whole name? Jason