On Tue, Nov 05, 2024 at 12:04:16PM -0800, Nicolin Chen wrote: > This series introduces a new vIOMMU infrastructure and related ioctls. > > IOMMUFD has been using the HWPT infrastructure for all cases, including a > nested IO page table support. Yet, there're limitations for an HWPT-based > structure to support some advanced HW-accelerated features, such as CMDQV > on NVIDIA Grace, and HW-accelerated vIOMMU on AMD. Even for a multi-IOMMU > environment, it is not straightforward for nested HWPTs to share the same > parent HWPT (stage-2 IO pagetable), with the HWPT infrastructure alone: a > parent HWPT typically hold one stage-2 IO pagetable and tag it with only > one ID in the cache entries. When sharing one large stage-2 IO pagetable > across physical IOMMU instances, that one ID may not always be available > across all the IOMMU instances. In other word, it's ideal for SW to have > a different container for the stage-2 IO pagetable so it can hold another > ID that's available. And this container will be able to hold some advanced > feature too.
Applied to iommufd for-next, thanks Jason
