Re: [PATCH v2 0/4] iommufd: Add iommu hardware info reporting

[Jason Gunthorpe]

On Wed, Mar 08, 2023 at 11:53:54PM -0800, 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. So before set up nested translation, userspace
> needs to know the hardware iommu information. 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.
> 
> This series reports the iommu hardware information for a given iommufd_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_DEVICE_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 picture is available in [1] as well.

Other than the small notes this looks pretty good to me

Jason