On Tue, Jul 29, 2025 at 02:07:55PM +0530, Aneesh Kumar K.V wrote: > > But it looks really strange to have an iommufd ioctl that just calls a > > KVM function. Feeling this should be a KVM function, or a guestmfd > > behavior?? > > > This functionality is equivalent to `IOMMU_IOAS_MAP`, but in the > presence of firmware like RMM, we also need to supply the realm > descriptor associated with the KVM instance. There is no IOAS here because the secure world is using the KVM page table. Since KVM owns this I don't see why iommufd should be invovled in any way. You need KVM to push the guestmemfd to the RMM and pin all the memory. > > I was kind of thinking it would be nice to have a guestmemfd mode that > > was "pinned", meaning the memory is allocated and remains almost > > always mapped into the TSM's page tables automatically. VFIO using > > guests would set things this way. > > We need to allocate and free these pages dynamically as they are > converted between private and shared states. That's still within guestmemfd's area of concern and it can immediately pin on state changes. Jason
