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. > > When an IO page fault occurs on the first-stage translation table, the > IOMMU hardware can deliver the page fault to user space through the > IOMMUFD framework. User space can then handle the page fault and respond > to the device top-down through the IOMMUFD. This allows user space to > implement its own IO page fault handling policies. > > 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 probably backwards, userspace should allocate the FD with a dedicated ioctl and provide it during domain allocation. If the userspace wants a fd per domain then it should do that. If it wants to share fds between domains that should work too. Jason
