On Mon, Sep 16, 2024 at 01:30:54PM +0200, James Gowans wrote: > Now actually implementing the serialise callback for iommufd. > On KHO activate, iterate through all persisted domains and write their > metadata to the device tree format. For now just a few fields are > serialised to demonstrate the concept. To actually make this useful a > lot more field and related objects will need to be serialised too. But isn't that a rather difficult problem? The "a lot more fields" include things like pointers to the mm struct, the user_struct and task_struct, then all the pinning accounting as well. Coming work extends this to memfds and more is coming. I would expect this KHO stuff to use the memfd-like path to access the physical VM memory too. I think expecting to serialize and restore everything like this is probably much too complicated. If you could just retain a small portion and then directly reconstruct the missing parts it seems like it would be more maintainable. Ie "recover" a HWPT from a KHO on a manually created a IOAS with the right "memfd" for the backing storage. Then the recovery can just validate that things are correct and adopt the iommu_domain as the hwpt. Eventually you'll want this to work for the viommus as well, and that seems like a lot more tricky complexity.. Jason
