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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?+L2Mb0bao4yEweRnZwmrTrDgJ2oKe512jiffDB+ZpYxT3g98cQsFHCHiJUOO?= =?us-ascii?Q?LyCl7UJmNS2kmFkmxoJrVtFeoJjS1y14ykhIdEE0ZRoe0ODAF+lCz8t1KI1L?= =?us-ascii?Q?dCmL4G3t9BIw5PiNCOvbUhwwAMGRjziK/fQ8yJJ1+zDGPKnp6BUldD1dm4yV?= =?us-ascii?Q?08KttBXtdfgrXT7wmSMVBho3usaC7yREempBKUG/gSA3IC89L6eKlr4tqLX6?= =?us-ascii?Q?z42BRsaxGAJRg+zUOZqleSHbJzZPFXjhD2E/y2twIYpHfUVONKvjrij/THOI?= =?us-ascii?Q?pMxGnwsHR/yBDT2E48gZGabVDN/0BYwI/bwRVqcAopN+Vs/2OlsULyCPxU14?= =?us-ascii?Q?CaQDGR37BFILLMTgLMyqT35F/mBDk+SZElJwRtLVWfSvEuDpG0WgUsjkc4LM?= =?us-ascii?Q?ixUCJ6W7dtD8WimNp0sNov34gnp+fqLwb3OPMgnoKMOivWuMH7kZ+TAu2Qnb?= =?us-ascii?Q?V20W8hpEKndcgUJaVaQR2AHeKoKVhK1wkHlH9xLv4aKZPeltV15z+zXxaOUo?= =?us-ascii?Q?yaP66sBqz5QdGmiaSe1HPV8RJf5qptiGTEfyZO0zN/lerIM/U9bsOE8kQEPz?= =?us-ascii?Q?rv5K1ybFAld+ae5HL+vvI+/mGGt/Ds8KM/Mm1A0/iItaNOWXnprnKTuuoaTU?= =?us-ascii?Q?f104ix5EfMYXHLkk8eLKRgETmJ5uS9rDrSTYfF47w5xHYM2SRupY6UXInRVO?= =?us-ascii?Q?BgsiKvdVtT52FcLp701eR8CG68ojaGLmwc5vI9375YlcKpLuLlTTWV7OqYb0?= =?us-ascii?Q?CTWMpcV/eowgJLe8eEFN/EKiIVqNE5P9T5CGX5TZV/cjekOEkvL6C+iuCQjy?= =?us-ascii?Q?Wz97VPDrKlWG55hbodhghYOuK/pJZiOsKGo1j6aONRSV/YyRRz04ah/7Dddh?= =?us-ascii?Q?dT3c+zAk9hpq3Mxs29NFVoOan2BTw3wshEu5blx+4ll4/c8F23Le0+jN4a1H?= =?us-ascii?Q?Dv2AJZ9bfX9u1E38198oIsdbvN0yW1M5+S5Ey7LukFtnqhH0WzFdUSvwXsyW?= =?us-ascii?Q?VCf7Q9cNv4tEwWKvNN04h1jBUpHMp72KN3f9AJ7JLpXtx5GUXsdEHnvvBZar?= =?us-ascii?Q?Tif6XTr2ho4Op49uoEvPciadnqi/DWmGrDM2niFn3s3xBcnMDV7yzmtrVOe8?= =?us-ascii?Q?2qckCqLtat+X+lfjjCE+OD2RGhkCZhcDJn2bJOxiAGKwe8KwAw9oYOAa1oNd?= =?us-ascii?Q?zaZ9EDj+38hqIYueyVGwME1uhaQx1m9x07wUBu9ZlR6rCUyrnxd21ddhzTE3?= =?us-ascii?Q?HKBNlayhY+9fQ9F6toxsGWTEx/VBQbCaZaxd1lRardPovBCfOoYjVk2pYCzS?= =?us-ascii?Q?sil3Qci/6EtEEBj3/9xxW56lgsKR4QQMWzLSi8DLCWqvzJabyviy4JyAZHF6?= =?us-ascii?Q?eWJMjvj/U/YJYB/R2JOqoe0VtTOEGFxprMHA9mtZTd/H4GAn+GvqoV0T9OCb?= =?us-ascii?Q?mIjtddP2glZ6Nvape4y0Fg9zT+a7YjTwlYdGjs/izq/Pf96YUKUmuvdjvYN4?= =?us-ascii?Q?H0HzhMedSQn/QqStHqjMdhoFCBXS+7vXQznXjRYhYydh+Vv27alD65PfNGyV?= =?us-ascii?Q?h+rKe1xR6NpWP3MZZFw3a+SsHadHSHdCdwtylzMu?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 088c1f57-6071-4c7f-c338-08da811e4329 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2022 13:33:40.3251 (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: qMtShXrXEYbasRBJSUtdq1G36Y/XfQ7kx3jhtWXOVYH/JNJbMQ8Hq8mBO9YMbMdB X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR12MB1396 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 17, 2022 at 09:20:16AM +0800, Lu Baolu wrote: > +static int __iommu_set_group_pasid(struct iommu_domain *domain, > + struct iommu_group *group, ioasid_t pasid) > +{ > + struct iommu_domain *ops_domain; > + struct group_device *device; > + int ret = 0; > + > + if (domain == group->blocking_domain) > + ops_domain = xa_load(&group->pasid_array, pasid); > + else > + ops_domain = domain; This seems weird, why isn't this just always domain->ops->set_dev_pasid()? > + if (curr) { > + ret = xa_err(curr) ? : -EBUSY; > + goto out_unlock; > + } > + > + ret = __iommu_set_group_pasid(domain, group, pasid); > + if (ret) { > + __iommu_set_group_pasid(group->blocking_domain, group, pasid); > + xa_erase(&group->pasid_array, pasid); I was looking at this trying to figure out why we are having attach/detach semantics vs set and this error handling seems to be the reason Lets add a comment because it is subtle thing: Setting a PASID to a blocking domain cannot fail, so we can always safely error unwind a failure to attach a domain back to the original group configuration of the PASID being unused. > +/* > + * iommu_detach_device_pasid() - Detach the domain from pasid of device > + * @domain: the iommu domain. > + * @dev: the attached device. > + * @pasid: the pasid of the device. > + * > + * The @domain must have been attached to @pasid of the @dev with > + * iommu_attach_device_pasid(). > + */ > +void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev, > + ioasid_t pasid) Don't pass domain here? > +/* > + * iommu_get_domain_for_dev_pasid() - Retrieve domain for @pasid of @dev > + * @dev: the queried device > + * @pasid: the pasid of the device > + * > + * This is a variant of iommu_get_domain_for_dev(). It returns the existing > + * domain attached to pasid of a device. It's only for internal use of the > + * IOMMU subsystem. The caller must take care to avoid any possible > + * use-after-free case. How exactly does the caller manage that? > + * > + * Return: attached domain on success, NULL otherwise. > + */ > +struct iommu_domain * > +iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid) > +{ > + struct iommu_domain *domain; > + struct iommu_group *group; > + > + if (!pasid_valid(pasid)) > + return NULL; Why bother? If the pasid is not valid then it definitely won't be in the xarray. But otherwise this overall thing seems fine to me Jason