Introduce new flag (IOMMU_HWPT_ALLOC_PASID) to domain_alloc_users() ops. If IOMMU supports PASID it will allocate domain. Otherwise return error. In error path check for -EOPNOTSUPP and try to allocate non-PASID domain so that DMA-API mode work fine for drivers which does not support PASID as well. Also modify __iommu_group_alloc_default_domain() to call iommu_paging_domain_alloc_flags() with appropriate flag when allocating paging domain. Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca> Co-developed-by: Vasant Hegde <vasant.hegde@amd.com> Signed-off-by: Vasant Hegde <vasant.hegde@amd.com> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Link: https://lore.kernel.org/r/20241028093810.5901-4-vasant.hegde@amd.com Signed-off-by: Joerg Roedel <jroedel@suse.de>