> From: Jason Wang <jasowang@xxxxxxxxxx> > Sent: Thursday, March 24, 2022 11:51 AM > > > > > > > > In the end vfio type1 will be replaced by iommufd compat layer. With > > that goal in mind iommufd has to inherit type1 behaviors. > > So the compatibility should be provided by the compat layer instead of > the core iommufd. > > And I wonder what happens if iommufd is used by other subsystems like > vDPA. Does it mean vDPA needs to inherit type1 behaviours? If yes, do > we need a per subsystem new uAPI to expose this capability? If yes, > why can't VFIO have such an API then we don't even need the compat > layer at all? > No, compat layer is just for vfio. other subsystems including vdpa is expected to use iommu uAPI directly, except having their own bind_iommufd and attach_ioas uAPIs to build the connection between device and iommufd/ioas. And having a compat layer for vfio is just for transition purpose. Yi has demonstrated how vfio can follow what other subsystems are expected to do here: https://github.com/luxis1999/iommufd/commits/iommufd-v5.17-rc6 (specifically commits related to "cover-letter: Adapting vfio-pci to iommufd") Thanks Kevin
