On Tue, Feb 28, 2023 at 02:51:28AM +0000, Liu, Yi L wrote: > > This seems strange. no iommu mode should have a NULL dev->iommufctx. > > Why do we have a df->noiommu at all? > > This is due to the vfio_device_first_open(). Detail as below comment (part of > patch 0016). > > + /* > + * For group/container path, iommufd pointer is NULL when comes > + * into this helper. Its noiommu support is handled by > + * vfio_device_group_use_iommu() > + * > + * For iommufd compat mode, iommufd pointer here is a valid value. > + * Its noiommu support is in vfio_iommufd_bind(). > + * > + * For device cdev path, iommufd pointer here is a valid value for > + * normal cases, but it is NULL if it's noiommu. Check df->noiommu > + * to differentiate cdev noiommu from the group/container path which > + * also passes NULL iommufd pointer in. If set then do nothing. > + */ If the group is in iommufd mode then it should set this pointer too. Jason
