On Tue, Sep 22, 2020 at 02:10:37PM +0800, Lu Baolu wrote: > Hi Jorge and Alex, > > A description of this patch series could be found here. > > https://lore.kernel.org/linux-iommu/20200901033422.22249-1-baolu.lu@xxxxxxxxxxxxxxx/ Hmm, I am wondering if we can avoid all this hassle and special APIs by making the mdev framework more visible outside of the vfio code. There is an underlying bus implementation for mdevs, so is there a reason those can't use the standard iommu-core code to setup IOMMU mappings? What speaks against doing: - IOMMU drivers capable of handling mdevs register iommu-ops for the mdev_bus. - iommu_domain_alloc() takes bus_type as parameter, so there can be special domains be allocated for mdevs. - Group creation and domain allocation will happen automatically in the iommu-core when a new mdev is registered through device-driver core code. - There should be no need for special iommu_aux_* APIs, as one can attach a domain directly to &mdev->dev with iommu_attach_device(domain, &mdev->dev). Doing it this way will probably also keep the mdev-special code in VFIO small. Regards, Joerg
