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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?wswE3pIfxZbTKsUzF+6sst4J3x3rNGDr8FTpfVb9U/VmHOwNneoqbNxyru4t?= =?us-ascii?Q?3RLj4Vbom3kzX5HVGWHPcmV1zHaig/T4beLLfUqupXvO/0TIykYROZuOHBMg?= =?us-ascii?Q?GkGBmaG6HuwNGwhApYDf45zBQpUf00ukMHQHpX7XywZ/6gwkLW3/UYUolRp1?= =?us-ascii?Q?57bcqWFaAc3N6UpKc9orQ9PtyYuogOOM77aLjI/m1whWdJQr6/h9ANGpQ7gS?= =?us-ascii?Q?Ae8zO+7RK6uqZJwkTEHpiUzpvfD6VaXSVWlmBqx7w/dkJHIpDxQL9x6/Jek/?= =?us-ascii?Q?D3X3bikisoHhtVBoB9M44AvgZOi+EQO4KiE6QDlpldERqxrM4HXM+PWtoAxR?= =?us-ascii?Q?j+GIjfTOAokzjHUOKTIb9ue0m6YtQyoYwd+JcFX1+1jVCP8o+AzhacoOWt0c?= =?us-ascii?Q?xZ69iqoQWO7LaiIVwxJKrP5tBFNAd4xVsdw0Ym6UZWX3GliSKAgbV9S92LIT?= =?us-ascii?Q?ZKi3NJezfN6X898WCTyLv6+nz8MJWnStkz8m9hi5uM0QDzkx0YArCH61T5PV?= =?us-ascii?Q?nlLqMKeQ3s5ab8T+GIKMwHbtike8NNsb34zfeJU1vkJ8LnhxmCM7YU7Camsz?= =?us-ascii?Q?QUACud74qtLAkewM2nWXySkgsJR9utPOR6nLxHYn3HVznnr7pxPJQKrUu/CB?= =?us-ascii?Q?jLpdk0AmDx0se/0TSXvDyxsmllEAFEqpyr+3rAhgbUQgU/unnmq5do00tbL8?= =?us-ascii?Q?9sqLuOVCdnU+snB60z0alY8alKmYTrYU4nv2r+KVHOP7agF0VQMm/7FpmE8A?= =?us-ascii?Q?WAz69r6YHU36LTKZ4YfkyguvFmw+XsDHcJ6YWELfDuD/kfrpPN2GrhqOlIre?= =?us-ascii?Q?xLYhrpTTO1JS9BNriz1PIkuP1uG7dblzgHAd4EuHMwZzJb7QeRNhVPwHev4L?= =?us-ascii?Q?TeTvPnx9b0V1hVt6Zlz1zC8Bb1q5wn2oZLpqdHb1wLa1eblzGA3jrIOaYmZ9?= =?us-ascii?Q?tZD9fhJu1IEi4HuOCp+fS+R1fPdwZnsGOu/+XRdAJfMOVlBRC6zixeHf1QFg?= =?us-ascii?Q?IXJFolor94PRbws/Yy7bUDfcCbMHO3OEw+WdNcHseCh7xSYkaF/h5FB9+Kv6?= =?us-ascii?Q?uZJNQAusRqT+vaa0bdiCiB5LsfE2ILTeT9cZ0+GF5twGs91D8vdUiFcZ6DNx?= =?us-ascii?Q?ZhCbpu11Dzps9oUeSaL19LwtJtiHhUDn0lLHN6fq3A9z0OUfAoYxCYVYNMDZ?= =?us-ascii?Q?GrKnmQm/yIYKwmgEME5M56jMLK8gBS1sbdl7j1CBULUwJTBu3yztMdBt9/qB?= =?us-ascii?Q?wr7PU8wIC8Z//+Do0BnWNm2CmuManhc3aTFzEw8P95XigYws1aqOfhEv9FRs?= =?us-ascii?Q?m3WFcbca5DKwPz7cLTEiG4NyOUnEleIeZdrn65Sqr8b6Yo0tDa02p99m9yMF?= =?us-ascii?Q?SZCpX83HleE+jfrnfmIpppLuWX6NhrY/CMoP1XTjFv9ALq2Tc68v5RsmPcZh?= =?us-ascii?Q?LOfIVPn1N/ev1/rkRFDiLxdUFG+9thr7rzESK26K/KXWuo31iwRKgy7LrYsO?= =?us-ascii?Q?8QPyeqDpTlvqbqqIG9oLgU6rAUfXmDiB9CFQjAnAK8eftMNzNuib72e+Qnu+?= =?us-ascii?Q?HVyqWO0yzAmnkLnVA49Q6cyz3PFFlMl4c45qR1Ms?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7ce2790d-faf5-4d2b-4687-08da925be108 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Sep 2022 12:07:34.3953 (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: ejCYihcDn46SxiPdi4juY2L32J5j6+PYHbbkbIWsrp7LTbDa8hyspCKJZk2OgCl2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ1PR12MB6243 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 09, 2022 at 05:00:16AM +0000, Tian, Kevin wrote: > > I have started this effort by combining this list and the one from > > the side thread: > > > > @@ -266,6 +266,13 @@ struct iommu_ops { > > /** > > * struct iommu_domain_ops - domain specific operations > > * @attach_dev: attach an iommu domain to a device > > + * Rules of its return errno: > > + * ENOMEM - Out of memory > > + * EINVAL - Device and domain are incompatible > > + * EBUSY - Device is attached to a domain and cannot be changed > > With this definition then probably @attach_dev should not return -EBUSY > at all given it's already checked in the start of __iommu_attach_group(): I think the EBUSY would be only for non-conforming drivers. The API semantic is you can always attach a new domain and replace an existing domain. So things like AMD's "can't do anything but idenitity on RID when PASID enabled" would be -EBUSY. Seems right that it should be rare though. > > + * ENODEV - Device or domain is messed up: device is not mapped > > + * to an IOMMU, no domain can attach, and etc. > > if domain is messed up then should return -EINVAL given using another domain > might just work. IMHO here -ENODEV should only cover device specific problems > preventing this device from being attached to by any domain. Agree > > + * - Same behavior as ENODEV, use is discouraged > > didn't get the "Same behavior" part. Does it suggest all other errnos should > be converted to ENODEV? It says all other errnos should be treated as ENODEV by the caller but forwarded to userspace for further detail. > btw what about -ENOSPC? It's sane to allocate some resource in the attach > path while the resource might be not available, e.g.: Seems resaonable that it is similar to ENOMEM > As discussed in a side thread a note might be added to exempt calling > kAPI outside of the iommu driver. Sadly, not really.. The driver is responsible to santize this if it is relevant. It is the main downside of this approach. Jason