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Thu, 20 Mar 2025 10:24:58 -0700 Date: Thu, 20 Mar 2025 10:24:56 -0700 From: Nicolin Chen To: Yi Liu CC: , , , , Subject: Re: [PATCH v10 02/18] iommu: Introduce a replace API for device pasid Message-ID: References: <20250320134744.5777-1-yi.l.liu@intel.com> <20250320134744.5777-3-yi.l.liu@intel.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250320134744.5777-3-yi.l.liu@intel.com> X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN1PEPF0000F0E4:EE_|DM4PR12MB5938:EE_ X-MS-Office365-Filtering-Correlation-Id: 83b940e9-3ec4-4616-dbe1-08dd67d42c28 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|82310400026|36860700013|7053199007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?YL8i9OwGrASQrmaJ3ZWqSiMM4apz3R0yGlu1kAYaD7lDpPlEsyHnAfbO06tD?= =?us-ascii?Q?A7tnWzMgCHK15NMZDktwsfhIafuvLbdlX4PsYmR3W8RBggm0l6YGZwwBsuKb?= =?us-ascii?Q?vymc64Y9bxDGRDP0d6zYNhLOt4vp+X1Osb/m6h2XhIEEUfOgvXNb2lN3oLJL?= =?us-ascii?Q?HBJjn/tJLh9TDJY7ZHGGhdLN+ggSz2wlTWKuidST64ygWnS8fk5aJDBxG4XJ?= =?us-ascii?Q?555E+g/p/VmavsLcmi+RqslGciue1Ao40qCSewN2YEOnxW/vcNdzzX2ju47B?= =?us-ascii?Q?QLrYNHAeBk4cJYo2/AG0wHwQL+cAqYHMGvKDLvXfd7fgH5iS9ik/T9CC9/8D?= =?us-ascii?Q?+Jy2t8byubTP/82FSghFpv7GcHVHvZdDR1cTdGAk7yxVInEeIXmXUKlDixb7?= =?us-ascii?Q?j5AtLmXyMxTZhNybdOryIJnvjdpLAqKqatViZB2TZcMT8o/ibvxOBv5dZyV9?= =?us-ascii?Q?P6+U85Um8EhUws+pdObBq1TzSxBdF6PLzIeABLmniXRj9ZLIbekm00uPwg2L?= =?us-ascii?Q?RPnX5cF2BIZ2bM1F+wfbmZPyEe2ryc5j96ZKRzAGNd4pZZvlG8geEE6DAJ7W?= =?us-ascii?Q?D3ZVCpWwoZB9YeRkfdj3jyoiS23sbTUPEmms7luHu8/00q8/Xa8hag21JL2Q?= =?us-ascii?Q?4iz4Az+2uHsZcoLkigtqhospcVOwRHdaKL2OqNPg/QK6BIOjR9GIfTLeW9ZG?= =?us-ascii?Q?h/iIjcAaOBtUC/ygBZ0zLdvje7m6pL7Zc/rqgl//XP5tYZ1S/bp6qGM1GqLU?= =?us-ascii?Q?KSyFQo2qiVI0JYWQAi9uOzQj52OcVXgcNSTrj+UDV26SDm9gyx8nMYVN0dm4?= =?us-ascii?Q?Mog9FNSWTyaM9Qzd1wSf8JVajRsZsCpUnPu1v00YHNryGcMbWXoaQKbD1mn/?= =?us-ascii?Q?DafP0Nd2YE/aOx8KHZ5F1vZyEsuahkZ7HfiCS9T2CZqSuc/H2vND8DbmlGaj?= =?us-ascii?Q?uUqkCORD6ryeZqtCf26BQc6OE9rKZPgL+FIB1VjFcPN2JfCzPiH9Kq4qBrJY?= =?us-ascii?Q?baZn/rUHUDJ+mfR190W2OW53vhq6wp457Do5ta5N3spAkrRT3Zp3pT4kxfnt?= =?us-ascii?Q?QfTDSzMJgLoU2kYPe82hKKR1Z/TE6PQoGrJ5AGoQbklrbdYUTtUD6/2sVe7d?= =?us-ascii?Q?WypUKpvxT/QaDlzhZL5Y8GCwMI2P8RhHogzk+UZMwH60wGHn0bw9M00Y80Jh?= =?us-ascii?Q?GGA2GfKk3cIXPdPd1gANnJ2Nkcb3BADsO3b3a4NVfJlKZ0X9fXzHOLjOrfzj?= =?us-ascii?Q?cOZ8N2nmvDIrygVFy+MNw7eZL0bOAwOoCz0U1KDXxg3MrYXpUFNyGdW6zzzW?= =?us-ascii?Q?k73/9Jn2yjet+0huIppFgG3D1o0iuAKb+V5w8hjYYwbr1ACUZPvVqgQsbl4z?= =?us-ascii?Q?J8egAd6mWoD7hCXMHrZmW9ePTogOI6PtuAvnHfM0VVBjSMbfAHhEOwffIUwK?= =?us-ascii?Q?beAvuWn48rCdXHZkG3tcEwJiaCNnRklMM4Kvl/uowz7mjulDs9O9FK31CSWq?= =?us-ascii?Q?CKQdoQrskkqcDog=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(376014)(82310400026)(36860700013)(7053199007);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Mar 2025 17:25:12.6362 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 83b940e9-3ec4-4616-dbe1-08dd67d42c28 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: MN1PEPF0000F0E4.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5938 On Thu, Mar 20, 2025 at 06:47:28AM -0700, Yi Liu wrote: > Provide a high-level API to allow replacements of one domain with another > for specific pasid of a device. This is similar to > iommu_replace_group_handle() and it is expected to be used only by IOMMUFD. > > Co-developed-by: Lu Baolu > Signed-off-by: Lu Baolu > Reviewed-by: Jason Gunthorpe > Reviewed-by: Kevin Tian > Signed-off-by: Yi Liu Reviewed-by: Nicolin Chen Some nits: > @@ -3420,6 +3436,99 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, > } > EXPORT_SYMBOL_GPL(iommu_attach_device_pasid); > > +/** > + * iommu_replace_device_pasid - Replace the domain that a pasid > + * is attached to How about "... a specific pasid of the device is attached to" aligning with the clearer narrative in commit log? > +int iommu_replace_device_pasid(struct iommu_domain *domain, > + struct device *dev, ioasid_t pasid, > + struct iommu_attach_handle *handle) > +{ > + /* Caller must be a probed driver on dev */ What's "a probed driver on dev"? Mind rephrasing this? Also should it be placed outside this function? > + struct iommu_group *group = dev->iommu_group; > + struct iommu_attach_handle *entry; > + struct iommu_domain *curr_domain; > + void *curr; > + int ret; > + > + if (!group) > + return -ENODEV; > + > + if (!domain->ops->set_dev_pasid) > + return -EOPNOTSUPP; > + > + if (dev_iommu_ops(dev) != domain->owner || > + pasid == IOMMU_NO_PASID || !handle) > + return -EINVAL; > + > + mutex_lock(&group->mutex); How about guard(mutex)(&group->mutex)? > + entry = iommu_make_pasid_array_entry(domain, handle); > + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, > + XA_ZERO_ENTRY, GFP_KERNEL); > + if (xa_is_err(curr)) { > + ret = xa_err(curr); > + goto out_unlock; > + } > + > + /* > + * No domain (with or without handle) attached, hence not > + * a replace case. > + */ > + if (!curr) { > + xa_release(&group->pasid_array, pasid); > + ret = -EINVAL; > + goto out_unlock; > + } > + > + /* > + * Reusing handle is problematic as there are paths that refers > + * the handle without lock. To avoid race, reject the callers that > + * attempt it. > + */ > + if (handle && curr == entry) { > + WARN_ON(1); > + ret = -EINVAL; > + goto out_unlock; > + } We rejected !handle and !curr cases. So it should be enough with: if (curr == entry) { ? > + > + curr_domain = pasid_array_entry_to_domain(curr); > + ret = 0; > + > + if (curr_domain != domain) { > + ret = __iommu_set_group_pasid(domain, group, > + pasid, curr_domain); > + if (ret) > + goto out_unlock; > + } Oh, does this mean that we can just use this function to replace a handle if domain isn't changed? Maybe add this in the kdoc? > + > + if (curr != entry) { Hmm, since we rejected "curr == entry" already, we don't need to double check any more? > + /* > + * The above xa_cmpxchg() reserved the memory, and the > + * group->mutex is held, this cannot fail. > + */ > + WARN_ON(xa_is_err(xa_store(&group->pasid_array, > + pasid, entry, GFP_KERNEL))); > + } > + > +out_unlock: > + mutex_unlock(&group->mutex); > + return ret; > +} > +EXPORT_SYMBOL_NS_GPL(iommu_replace_device_pasid, "IOMMUFD_INTERNAL"); > + > /* > * iommu_detach_device_pasid() - Detach the domain from pasid of device > * @domain: the iommu domain. > -- > 2.34.1 >