On Fri, Aug 11, 2023 at 12:14:57AM -0700, Yi Liu wrote:
iommufd gives userspace the capability to manipulate iommu subsytem. e.g. DMA map/unmap etc. In the near future, it will support iommu nested translation. Different platform vendors have different implementation for the nested translation. For example, Intel VT-d supports using guest I/O page table as the stage-1 translation table. This requires guest I/O page table be compatible with hardware IOMMU. So before set up nested translation, userspace needs to know the hardware iommu information to understand the nested translation requirements.
This series reports the iommu hardware information for a given device which has been bound to iommufd. It is preparation work for userspace to allocate hwpt for given device. Like the nested translation support[1].
This series introduces an iommu op to report the iommu hardware info, and an ioctl IOMMU_GET_HW_INFO is added to report such hardware info to user. enum iommu_hw_info_type is defined to differentiate the iommu hardware info reported to user hence user can decode them. This series only adds the framework for iommu hw info reporting, the complete reporting path needs vendor specific definition and driver support. The full code is available in [1] as well.
[1] https://github.com/yiliu1765/iommufd/tree/wip/iommufd_nesting_08112023-yi (only the hw_info report path is the latest, other parts is wip)
I made the changes I noted and pull these plus the single vt-d patch into iommufd for-next
Let me know if it is not OK and we can back it out
Thanks, Jason