On Mon, 2024-02-05 at 10:10 -0700, Alex Williamson wrote: > > * Needing to drive and re-hydrate the IOMMU page tables by defining > > an IOMMU file. > > Really we should move the abstraction one level up and make the > > whole VFIO > > container persistent via a pkernfs file. That way you’d "just" re- > > open the VFIO > > container file and all of the DMA mappings inside VFIO would already > > be set up. > > Note that the vfio container is on a path towards deprecation, this > should be refocused on vfio relative to iommufd. There would need to > be a strong argument for a container/type1 extension to support this, > iommufd would need to be the first class implementation. Thanks, Ack! When I first started putting pkernfs together, iommufd wasn't integrated into QEMU yet, hence I stuck with VFIO for this PoC. I'm thrilled to see that iommufd now seems to be integrated in QEMU! Good opportunity to get to grips with it. The VFIO-specific part of this patch is essentially ioctls on the *container* to be able to: 1. define persistent page tables (PPTs) on the containers so that those PPTs are used by the IOMMU domain and hence by all devices added to that container. https://github.com/jgowans/qemu/commit/e84cfb8186d71f797ef1f72d57d873222a9b479e 2. Tell VFIO to avoid mapping the memory in again after live update because it already exists. https://github.com/jgowans/qemu/commit/6e4f17f703eaf2a6f1e4cb2576d61683eaee02b0 (the above flag should only be set *after* live update...). Do you have a rough suggestion about how similar could be done with iommufd? JG
