On 13/10/2023 17:00, Joao Martins wrote: > On 13/10/2023 16:48, Jason Gunthorpe wrote: >> On Sat, Sep 23, 2023 at 02:24:54AM +0100, Joao Martins wrote: >>> Both VFIO and IOMMUFD will need iova bitmap for storing dirties and walking >>> the user bitmaps, so move to the common dependency into IOMMU core. IOMMUFD >>> can't exactly host it given that VFIO dirty tracking can be used without >>> IOMMUFD. >> >> Hum, this seems strange. Why not just make those VFIO drivers depends >> on iommufd? That seems harmless to me. >> > > IF you and Alex are OK with it then I can move to IOMMUFD. > >> However, I think the real issue is that iommu drivers need to use this >> API too for their part? >> > > Exactly. > My other concern into moving to IOMMUFD instead of core was VFIO_IOMMU_TYPE1, and if we always make it depend on IOMMUFD then we can't have what is today something supported because of VFIO_IOMMU_TYPE1 stuff with migration drivers (i.e. vfio-iommu-type1 with the live migration stuff). But if it's exists an IOMMUFD_DRIVER kconfig, then VFIO_CONTAINER can instead select the IOMMUFD_DRIVER alone so long as CONFIG_IOMMUFD isn't required? I am essentially talking about: # SPDX-License-Identifier: GPL-2.0-only menuconfig VFIO tristate "VFIO Non-Privileged userspace driver framework" select IOMMU_API depends on IOMMUFD || !IOMMUFD select INTERVAL_TREE select VFIO_GROUP if SPAPR_TCE_IOMMU || IOMMUFD=n select VFIO_DEVICE_CDEV if !VFIO_GROUP select VFIO_CONTAINER if IOMMUFD=n help VFIO provides a framework for secure userspace device drivers. See Documentation/driver-api/vfio.rst for more details. If you don't know what to do here, say N. ... and the fact that VFIO_IOMMU_TYPE1 requires VFIO_GROUP: config VFIO_CONTAINER bool "Support for the VFIO container /dev/vfio/vfio" select VFIO_IOMMU_TYPE1 if MMU && (X86 || S390 || ARM || ARM64) depends on VFIO_GROUP default y help The VFIO container is the classic interface to VFIO for establishing IOMMU mappings. If N is selected here then IOMMUFD must be used to manage the mappings. Unless testing IOMMUFD say Y here. if VFIO_CONTAINER config VFIO_IOMMU_TYPE1 tristate default n [...]
