On Thu, Apr 01, 2021 at 02:08:17PM +0000, Liu, Yi L wrote: > DMA page faults are delivered to root-complex via page request message and > it is per-device according to PCIe spec. Page request handling flow is: > > 1) iommu driver receives a page request from device > 2) iommu driver parses the page request message. Get the RID,PASID, faulted > page and requested permissions etc. > 3) iommu driver triggers fault handler registered by device driver with > iommu_report_device_fault()
This seems confused. The PASID should define how to handle the page fault, not the driver. I don't remember any device specific actions in ATS, so what is the driver supposed to do? > 4) device driver's fault handler signals an event FD to notify userspace to > fetch the information about the page fault. If it's VM case, inject the > page fault to VM and let guest to solve it. If the PASID is set to 'report page fault to userspace' then some event should come out of /dev/ioasid, or be reported to a linked eventfd, or whatever. If the PASID is set to 'SVM' then the fault should be passed to handle_mm_fault And so on. Userspace chooses what happens based on how they configure the PASID through /dev/ioasid. Why would a device driver get involved here? > Eric has sent below series for the page fault reporting for VM with passthru > device. > https://lore.kernel.org/kvm/20210223210625.604517-5-eric.au...@redhat.com/ It certainly should not be in vfio pci. Everything using a PASID needs this infrastructure, VDPA, mdev, PCI, CXL, etc. Jason _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
