> 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? > > So I'd like to see this generalized into a channel to carry any > events.. > > > 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? 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?
