On Tue, Nov 07, 2023 at 08:35:10AM +0000, Tian, Kevin wrote: > > From: Jason Gunthorpe <jgg@xxxxxxxx> > > Sent: Thursday, November 2, 2023 8:48 PM > > > > On Thu, Oct 26, 2023 at 10:49:24AM +0800, Lu Baolu wrote: > > > Hi folks, > > > > > > This series implements the functionality of delivering IO page faults to > > > user space through the IOMMUFD framework for nested translation. > > Nested > > > translation is a hardware feature that supports two-stage translation > > > tables for IOMMU. The second-stage translation table is managed by the > > > host VMM, while the first-stage translation table is owned by user > > > space. This allows user space to control the IOMMU mappings for its > > > devices. > > > > Having now looked more closely at the ARM requirements it seems we > > will need generic events, not just page fault events to have a > > complete emulation. > > Can you elaborate? There are many events related to object in guest memory or controlled by the guest, eg C_BAD_CD and C_BAD_STE. These should be relayed or the emulation is not working well. > > > User space indicates its capability of handling IO page faults by > > > setting the IOMMU_HWPT_ALLOC_IOPF_CAPABLE flag when allocating a > > > hardware page table (HWPT). IOMMUFD will then set up its infrastructure > > > for page fault delivery. On a successful return of HWPT allocation, the > > > user can retrieve and respond to page faults by reading and writing to > > > the file descriptor (FD) returned in out_fault_fd. > > > > This is the right way to approach it, and more broadly this shouldn't > > be an iommufd specific thing. Kernel drivers will also need to create > > fault capable PAGING iommu domains. > > Are you suggesting a common interface used by both iommufd and > kernel drivers? Yes > but I didn't get the last piece. If those domains are created by kernel > drivers why would they require a uAPI for userspace to specify fault > capable? Not to userspace, but a kapi to request a fault capable domain and to supply the fault handler. Eg: iommu_domain_alloc_faultable(dev, handler); Jason _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
