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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 May 2025 17:21:56.0304 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: f5a41d27-57e2-4798-1c04-08dd8bf955f3 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF00017092.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB7921 On Mon, May 05, 2025 at 01:50:19PM -0300, Jason Gunthorpe wrote: > On Mon, Apr 28, 2025 at 10:50:32AM +0800, Baolu Lu wrote: > > On 4/26/25 13:58, Nicolin Chen wrote: > > > +/* Entry for iommufd_ctx::mt_mmap */ > > > +struct iommufd_mmap { > > > + unsigned long pfn_start; > > > + unsigned long pfn_end; > > > +}; > > > > This structure is introduced to represent a mappable/mapped region, > > right? It would be better to add comments specifying whether the start > > and end are inclusive or exclusive. > > start/end are supposed to be non-inclusive range in iommufd > land. start/last for inclusive. > > This should be a u64 too Will fix. > > > +void iommufd_ctx_free_mmap(struct iommufd_ctx *ictx, unsigned long immap_id) > > > +{ > > > + kfree(mtree_erase(&ictx->mt_mmap, immap_id >> PAGE_SHIFT)); > > > > MMIO lifecycle question: what happens if a region is removed from the > > maple tree (and is therefore no longer mappable), but is still mapped > > and in use by userspace? > > I think we should probably zap it and make any existing VMAs > SIGBUS... Otherwise it is hard to reason about from the kernel side I added in v3 a pair of open/close op that would refcount the vIOMMU object (owner of the mmap region). This would EBUSY the vIOMMU destroy ioctl that would call this function. Thanks Nicolin