iommu: Add new flag to explictly request PASID capable domain

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>

include/uapi/linux/iommufd.h

@@ -359,11 +359,19 @@ struct iommu_vfio_ioas {
  *                                   enforced on device attachment
  * @IOMMU_HWPT_FAULT_ID_VALID: The fault_id field of hwpt allocation data is
  *                             valid.
+ * @IOMMU_HWPT_ALLOC_PASID: Requests a domain that can be used with PASID. The
+ *                          domain can be attached to any PASID on the device.
+ *                          Any domain attached to the non-PASID part of the
+ *                          device must also be flaged, otherwise attaching a
+ *                          PASID will blocked.
+ *                          If IOMMU does not support PASID it will return
+ *                          error (-EOPNOTSUPP).
  */
 enum iommufd_hwpt_alloc_flags {
 	IOMMU_HWPT_ALLOC_NEST_PARENT = 1 << 0,
 	IOMMU_HWPT_ALLOC_DIRTY_TRACKING = 1 << 1,
 	IOMMU_HWPT_FAULT_ID_VALID = 1 << 2,
+	IOMMU_HWPT_ALLOC_PASID = 1 << 3,
 };
 
 /**