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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?gQGXKawmqvQO5cA+RQesO9+oBW0ZwxER74HHk28Ax4lCq1y/IUWSXs0nNx58?= =?us-ascii?Q?M9ED00yTuTfPy72Eu+gb1vbRYbfZxnh2UA78VISZswKHVebya6NwwSxf2IXa?= =?us-ascii?Q?/mKy0wy2Bk2A9tJJHJVYQX6DEFOQ+f4VPzSX/EI9KdWRiLJjoKIzxakDGB+e?= =?us-ascii?Q?tpo7+WG1wlH5sReSSHjUvQfUzJgqwbqL1CFvn1guO/kw95KDHaZaIeG1nZ8R?= =?us-ascii?Q?p6Xeo2JLN9pVBX7+S+HxwugIb5c8MqqCeJlx27KZ5oCmQmcoEySDCAWpPv/L?= =?us-ascii?Q?2kXBNLdN6RqLdl+9VDr4h+1V3IkXjWaZkyr4dU6sfxaUJAmnXMKi32IvNvP8?= =?us-ascii?Q?2ong/gKAkaEP9hk/nZoDNb74RjaDA49rihb0idfoJBi9HekH2H4r6UiVz3fB?= =?us-ascii?Q?BLwd0j9SXh+plAGeyy3l9p2GyHjrykXo7411LBQdt+8cjQK6TEPfHtcdplNo?= =?us-ascii?Q?VQexzByJSxXAS1xACKEVnTT32H5hnrE3mxCo4mzpJ5lFrOUUoo86oGeXI2yF?= =?us-ascii?Q?Em1oMK15w4pGcgpcmG012dSNNWaJ2uuJ4LKcai/WNC/rJBrU0YvYBuZl6hmW?= =?us-ascii?Q?Kri/y4sBYX1UMzWBQLt8yXFOAnNFkTi7onaayxnc9vU3upBQsPx4jsNndfnJ?= =?us-ascii?Q?pjZ36wHZ37EcqA/Z0vQzBOKA4NXffDizFrKhyaAvp1AaZjhwYlffQeuJoBkT?= =?us-ascii?Q?rlfSOs6Rc1dx1mQYnMurucmDLXPC/NGW8L4ZjBQ5TcQ1tpdy2Q6WjZEdZLph?= =?us-ascii?Q?/ddnaLWmPQca/Zk/lvO4DkWUoz4vCz6hDt9PSFMwjg0A2fK9O4FrxIDTOYdP?= =?us-ascii?Q?UI9gtyVFbIiNDxVL249n6FrVAKjRECARFRznJm5v72+ZrSBRcUPhu5VyTS4e?= =?us-ascii?Q?vNgyHgIXumDPOBNkNBS3muWZ8dD35OFJmRx6MoLdg9Ffjw6JkR+Tz0I+TFsT?= =?us-ascii?Q?0eHf8NXF7xWKdEFJ9baiuDTpuiEVQSDUZsYD8BTRH2xvaZwkR54rfMwuP1xN?= =?us-ascii?Q?xbZyZd8UTKJQUh5wGsdbVgbx/6STy+JAGsUX3k0z9yRjsyISled8iM/wNuCh?= =?us-ascii?Q?xX/8iLTD3IBSLHSR6AQ0vRo27CvuyAC5CVVoNufikByQtQ1BeZ7WuW5C9cnK?= =?us-ascii?Q?6VqXzrdNxsBFvo4Jt+mWA4MbLbPKddDutqLkVrLDH2usImpPQkDbYHdFEKxE?= =?us-ascii?Q?2AFQZj+RIa59Wr2+SmZFzL6tmub15oO9NL5PeXtvWyBYVZWksWF8j/IZ3kYY?= =?us-ascii?Q?W1KfKc4FqsbjLoh9Js5/wGeMAwcqgoT0R9fLXIXAnzOQPMs5JY2vFruEbOTi?= =?us-ascii?Q?Oo/851TEHoQgHlrOTLDT9cGNYmMo2pHUxd76sao6KVpNJ/A6d5w5nh8ysuzG?= =?us-ascii?Q?iTbkspLyXtxiy5r1t6B4K9zcfo3QdCPqDZVdd/23b6eSpE7JKK6c/U76yAMU?= =?us-ascii?Q?cvl+rXkl360AJi3eMNOx+TeI5RlJx4GcQKipalf8DvZqHpP7NRW7BumgGPo2?= =?us-ascii?Q?sYl/29MuI3NDZwv+QoRg0o2OSXt4aI0yYgagDqfCBsp+gMnC1w5lC6nXZcN/?= =?us-ascii?Q?JBJ/xpOjSGRxig7umnef1E+wWKmVZNxdxcKCVpfEkgNsF117e03+S635H4AC?= =?us-ascii?Q?YyICkzdV04iUeUd9NjtALVACGya9MhCK8EccheavP6bApRvbti7prnc71WR+?= =?us-ascii?Q?DzMi64mWj3QM2e4mZo6V1p3IrE8KTae9MKLV5/sIQbHEyI0r?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2b68548d-d2c5-4233-0aed-08df1affc15d X-MS-Exchange-CrossTenant-AuthSource: LY0PR12MB325698.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Sep 2026 12:23:07.3886 (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: 0SnNOKw6+nCKuUjoRAQGBIKUumqqps/ywzSZdyBD/htyxBUvouCOsGrpkrMSfnrN X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB6335 On Fri, Sep 25, 2026 at 11:18:44AM +0530, Aneesh Kumar K.V wrote: > > The TSM viommu should use a NULL parent domain, it doesn't have an > > iommufd managed S2. > > How would we assign an untrusted device? I currently follow these steps: > 1. Create an HWPT with IOMMU_HWPT_ALLOC_NEST_PARENT. > 2. Allocate a vIOMMU with viommu.hwpt_id set to that hwpt_id. > 3. Allocate a vdevice with alloc_vdev.viommu_id set to that viommu_id. > 4. Use VFIO_DEVICE_ATTACH_IOMMUFD_PT with the hwpt_id. The vmiommu.hwpt_id should be 0. 1. Create a a HWPT with IOMMU_HWPT_ALLOC_NEST_PARENT 2. VFIO_DEVICE_ATTACH_IOMMUFD_PT with the hwpt_id to establish the T=0 identity S2, no T=0 vSMMU 3. Create a VIOMMU with no hwpt_id and the RMM's type. This triggers RMM to create the the T=1 vSMMU inside the realm 4. Allocate a vdevice on the viommu_id. This triggers RMM to create the VDEV inside the realm 5. Setup guest ACPI tables/etc to point at the RMM's T=1 vsmmu. Now both the T=1 VSUMM and T=0 fixed translation are setup. If we loose our minds someday and want to concurrently have a T=0&1 VSMMU then the the first two steps become: 1. Create a a HWPT with IOMMU_HWPT_ALLOC_NEST_PARENT 2. Create a VIOMMU with no hwpt_id and IOMMU_VIOMMU_TYPE_ARM_SMMUV3 3. Create a vdevice on #2, we'd need to fixup iommufd to support two vdevices for the same device. 4. Create a nested child HWPT IOMMU_HWPT_DATA_ARM_SMMUV3 from the T=0 vSTE 5. Use VFIO_DEVICE_ATTACH_IOMMUFD_PT on #3 ie there would be two viommu objects inside iommufd. > I use the same iommufd for both trusted and untrusted devices because > the guest controls that transition. While operating in untrusted mode, I > use the iommufd to insert DMA mappings via IOMMU_IOAS_MAP. Sure, that's not an issue, just don't create the *TSM VIOMMU* with a hwpt. TSM viommu driver just asserts the parent is NULL, since it doesn't use a S2. Jason