Robin points out that the fallback to guessing what domains the driver supports should only happen if the driver doesn't return a preference from its ops->def_domain_type(). Re-organize iommu_group_alloc_default_domain() so it internally uses iommu_def_domain_type only during the fallback and makes it clearer how the fallback sequence works. Make iommu_group_alloc_default_domain() return the domain so the return based logic is cleaner and to prepare for the next patch. Remove the iommu_alloc_default_domain() function as it is now trivially just calling iommu_group_alloc_default_domain(). Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Tested-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/13-v5-1b99ae392328+44574-iommu_err_unwind_jgg@nvidia.com Signed-off-by: Joerg Roedel <jroedel@suse.de>