On Tue, Apr 06, 2021 at 12:37:35AM +0000, Tian, Kevin wrote: > With nested translation it is GVA->GPA->HPA. The kernel needs to > fix fault related to GPA->HPA (managed by VFIO/VDPA) while > handle_mm_fault only handles HVA->HPA. In this case, the 2nd-level > page fault is expected to be delivered to VFIO/VDPA first which then > find HVA related to GPA, call handle_mm_fault to fix HVA->HPA, > and then call iommu_map to fix GPA->HPA in the IOMMU page table. > This is exactly like how CPU EPT violation is handled. No, it should all be in the /dev/ioasid layer not duplicated into every user. > > If the fault needs to be fixed in the guest, then it needs to be > > delivered over /dev/ioasid in some way and injected into the > > vIOMMU. VFIO and VDPA have nothing to do with vIOMMU driver in quemu. > > > > You need to have an interface under /dev/ioasid to create both page > > table levels and part of that will be to tell the kernel what VA is > > mapped and how to handle faults. > > VFIO/VDPA already have their own interface to manage GPA->HPA > mappings. Why do we want to duplicate it in /dev/ioasid? They have their own interface to manage other types of HW, we should not duplicate PASID programming into there too. Jason
