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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?2YP/1XsZZkJUihQIXPF5WxTgbdHgO+LRPWOtMChcJ7kE1XMXDrt/Vbdf42mr?= =?us-ascii?Q?yj4Gw9x6Xa42TgDTnqtdJkYqkg1wsHlkOj206xAZQo2PkFpoX0nA3zIKXXZl?= =?us-ascii?Q?x/ruQay3KD4uQXAWsSMr13PEwjWF7EcmMgdXTziyCaMwl8n4O87qXbwdkV5+?= =?us-ascii?Q?DZCM7rbnuYSeO1Z/dwEwJIdgjxCYbgj+6fpo8zFxvSR2MSWRXqNH7AXs9syT?= =?us-ascii?Q?NKwtOx5Mu4lWuTzQ7oyezoPgaTRNPDDQH2hIobhriLKdrH0vqtrhk/HDvHNR?= =?us-ascii?Q?7GNK/BM0xko1D87pyQAUwMw/gxWR6a1SmI6hChTatOXCsFtrM7HMz2wjvUg+?= =?us-ascii?Q?5htYgzZv2owkA7hyX9S2MBRpJccOzE6ckW/oK73eR9j/iCm/byfLuFZMCh6W?= =?us-ascii?Q?OYad1z6OunM39OlZvOMWa048BWmM5iBINJNwOaCc3BufSBYuvFSzV5IPdpNk?= =?us-ascii?Q?XZtPB/stpGWPjF5uKOUNhJPCl5fu+HLzQuH4gDE9ebLvoKb7qCzBOLU5SkcZ?= =?us-ascii?Q?Ol1nfPM/Sdg6JqWJDF1n6hv1Gf9sel6cMb5Eh6eUkq4AMe8pYFdeJDgkESMB?= =?us-ascii?Q?HEc37Q5dxPdrWbgripv2fN87N1BtU/ek5Ugbr8YO1sxsqnNUWlffZNZaglnZ?= =?us-ascii?Q?XiZEb/LeHKB1OSOWf0oZLnwiwGICt0DVtTbLdks7NrMmGO471kYitQFuK7QH?= =?us-ascii?Q?pytSGwDarFHBTKLQ6S+TqQGYzDyd74bPzG8tPzL/MbJf8X+X8wUclEV0kYTI?= =?us-ascii?Q?Qv9vsYp2voVrZ4HgMeUrGPnJXS2PCVJrF026LbKofe42SEQw3rRtC74ozMUV?= =?us-ascii?Q?z5EAshYojTpj44zQMwGCYs5cTWflK6EpG5TWyXrWKbePFspPvW9Zum8UQPzx?= =?us-ascii?Q?Z+uNnHUOpY3Nq3AALXsZXSMQ4gupnpxTJC3s4sgMF/zoRIvvRpnz1mroPVkM?= =?us-ascii?Q?8iP+D+fFTHSl94AgWQVcLx4wTt2Ahb58265uxl+X6v6PkAoyiIt9pfV2onjY?= =?us-ascii?Q?2D71tZDy8N+J8WHdXYWgq4fCKJkGTaxALkhnl8p5LLGcMo2IVMsSItIHzEJQ?= =?us-ascii?Q?6if/XsCztUL2qBymxjNjXobpNkDS040hJnmg6iTFoevLKof7Cpzaziz/yY4A?= =?us-ascii?Q?ZQiscMuBTZOORR9FGRgOXPOo6b5wcMtGaKZJX1ZKbiUe35dVWYNwNQK61cWI?= =?us-ascii?Q?OQFp+vMvU5nt8rAE/QOGD5gq+iPMsAD2BGdvxmjUBquW5401wkcslaVdaJXp?= =?us-ascii?Q?FogjUBTB/lYQL+96uZHE9lwp9jfoGajg4ymxigKMNLMcLk5tLNLu0msKsX+K?= =?us-ascii?Q?ksNmHDVUBS/ftJ3Nmv9V38GxpqSoxFOq6wxl+OiGnvOgQv4/KyQYen5nq7xO?= =?us-ascii?Q?+7Ov5qF07TCtTvzm7kvZdaHN4iKWc89V1luF9OR+7HfcluyI1T4J0DdGj8iv?= =?us-ascii?Q?m67f4q/F/crtlpXBCFwOgaD9pgS3ul/uquHVbPcXkcCrccrh/pslGGk8Jcfc?= =?us-ascii?Q?pRgBLsWTgyFNqcUFVV0J9mZ03ivWIGgxfpwPbgE6ykdJ6SNeqVDuhjET1Vjm?= =?us-ascii?Q?d57mU/8AQTzx4xg7yvU=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d87d598a-6492-4cc6-223c-08dac33fe477 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Nov 2022 17:20:41.0965 (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: YkNJF1WYwuNMPvvVeQIllu6UaEOJ10kM00nRj71x1ew1dNlxVeO6cVWO7ENGQEAy X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR12MB4524 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Thu, Nov 10, 2022 at 03:11:16AM +0000, Tian, Kevin wrote: > > From: Jason Gunthorpe > > Sent: Tuesday, November 8, 2022 8:53 AM > > > > + > > +int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx) > > +{ > > + u32 ioas_id; > > + u32 device_id; > > + int ret; > > + > > + lockdep_assert_held(&vdev->dev_set->lock); > > + > > + /* > > + * If the driver doesn't provide this op then it means the device does > > + * not do DMA at all. So nothing to do. > > + */ > > + if (!vdev->ops->bind_iommufd) > > + return 0; > > + > > + ret = vdev->ops->bind_iommufd(vdev, ictx, &device_id); > > + if (ret) > > + return ret; > > + > > + ret = iommufd_vfio_compat_ioas_id(ictx, &ioas_id); > > + if (ret) > > + goto err_unbind; > > + ret = vdev->ops->attach_ioas(vdev, &ioas_id); > > + if (ret) > > + goto err_unbind; > > with our discussion in v1: > > https://lore.kernel.org/all/Y2mgJqz8fvm54C+f@nvidia.com/ > > I got the rationale on iommufd part which doesn't have the concept > of container hence not necessarily to impose restriction on when > an user can change a compat ioas. > > But from vfio side I wonder whether we should cache the compat > ioas id when it's attached by the first device and then use it all the > way for other device attachments coming after. implying IOAS_SET > only affects containers which haven't been attached. I can't see a reason to do this. IOAS_SET is a new ioctl and it has new semantics beyond what original vfio container could do. In this case having an impact on the next vfio_device that is opened. This seems generally useful enough I wouldn't want to block it. In any case, we can't *really* change this because the vfio layer is working on IDs and the IDs can be destroyed/recreated from under it. So if we try to hold the ID we could still end up getting it changed anyhow. 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> > + u32 device_id; > > + int ret; > > + > > + lockdep_assert_held(&vdev->dev_set->lock); > > + > > + /* > > + * If the driver doesn't provide this op then it means the device does > > + * not do DMA at all. So nothing to do. > > + */ > > + if (!vdev->ops->bind_iommufd) > > + return 0; > > + > > + ret = vdev->ops->bind_iommufd(vdev, ictx, &device_id); > > + if (ret) > > + return ret; > > + > > + ret = iommufd_vfio_compat_ioas_id(ictx, &ioas_id); > > + if (ret) > > + goto err_unbind; > > + ret = vdev->ops->attach_ioas(vdev, &ioas_id); > > + if (ret) > > + goto err_unbind; > > with our discussion in v1: > > https://lore.kernel.org/all/Y2mgJqz8fvm54C+f@nvidia.com/ > > I got the rationale on iommufd part which doesn't have the concept > of container hence not necessarily to impose restriction on when > an user can change a compat ioas. > > But from vfio side I wonder whether we should cache the compat > ioas id when it's attached by the first device and then use it all the > way for other device attachments coming after. implying IOAS_SET > only affects containers which haven't been attached. I can't see a reason to do this. IOAS_SET is a new ioctl and it has new semantics beyond what original vfio container could do. In this case having an impact on the next vfio_device that is opened. This seems generally useful enough I wouldn't want to block it. In any case, we can't *really* change this because the vfio layer is working on IDs and the IDs can be destroyed/recreated from under it. So if we try to hold the ID we could still end up getting it changed anyhow. 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> > + u32 device_id; > > + int ret; > > + > > + lockdep_assert_held(&vdev->dev_set->lock); > > + > > + /* > > + * If the driver doesn't provide this op then it means the device does > > + * not do DMA at all. So nothing to do. > > + */ > > + if (!vdev->ops->bind_iommufd) > > + return 0; > > + > > + ret = vdev->ops->bind_iommufd(vdev, ictx, &device_id); > > + if (ret) > > + return ret; > > + > > + ret = iommufd_vfio_compat_ioas_id(ictx, &ioas_id); > > + if (ret) > > + goto err_unbind; > > + ret = vdev->ops->attach_ioas(vdev, &ioas_id); > > + if (ret) > > + goto err_unbind; > > with our discussion in v1: > > https://lore.kernel.org/all/Y2mgJqz8fvm54C+f@nvidia.com/ > > I got the rationale on iommufd part which doesn't have the concept > of container hence not necessarily to impose restriction on when > an user can change a compat ioas. > > But from vfio side I wonder whether we should cache the compat > ioas id when it's attached by the first device and then use it all the > way for other device attachments coming after. implying IOAS_SET > only affects containers which haven't been attached. I can't see a reason to do this. IOAS_SET is a new ioctl and it has new semantics beyond what original vfio container could do. In this case having an impact on the next vfio_device that is opened. This seems generally useful enough I wouldn't want to block it. In any case, we can't *really* change this because the vfio layer is working on IDs and the IDs can be destroyed/recreated from under it. So if we try to hold the ID we could still end up getting it changed anyhow. Jason