Re: [PATCH RFCv2] iommu: Add domain type and flag to domain_alloc_paging()

[Jason Gunthorpe <jgg@ziepe.ca>]

On Mon, Aug 12, 2024 at 02:51:56PM +0530, Vasant Hegde wrote:

> Let me summarize and see if I got everything right.
> 
> - Enhance iommufd_get_hw_info ioctl to get device PASID capability
>   HW driver will implement iommu_ops->capable() to check PASID capability
>
> - Userspace will use above info and calls iommu_ops->domain_alloc_user() with
>   appropriate flag (If PASID capability present then pass
>   IOMMU_HWPT_ALLOC_DEV_PASID as flag).
> 
> - HW driver : If IOMMU and dev supports PASID then allocate PASID capable
>   domain, else allocate normal domain.
> 
> - When attaching PASID to device (RID), PASID attachment will pass only domain
> supports PASID, else it will fail.
> 
> - IOMMU_HWPT_ALLOC_PASID  flag is optional:
>   If we endup implementing this flag, then it will allocate PASID capable domain
> if HW IOMMU supports it (It will not check device capability).

So how do you get a PASID domain with only one flag? You specify
IOMMU_HWPT_ALLOC_DEV_PASID and expect it to work for PASID attach too?

Jason