From: Nicolin Chen nicolinc@nvidia.com Sent: Wednesday, May 24, 2023 1:41 PM
On Wed, May 24, 2023 at 05:16:35AM +0000, Tian, Kevin wrote:
From: Nicolin Chen nicolinc@nvidia.com Sent: Saturday, May 20, 2023 3:48 AM
switch (pt_obj->type) {case IOMMUFD_OBJ_IOAS:ioas = container_of(pt_obj, struct iommufd_ioas, obj);break;this should fail if parent is specified.
I don't think that's necessaray: the parent is NULL by default and only specified (if IOMMUFD_OBJ_HW_PAGETABLE) by the exact pt_id/pt_obj here.
I didn't get. The uAPI describes that only hwpt not ioas can be specified in the pt_id field as the parent.
If we don't check here it means the user can specify an ioas id as the parent?
I meant that the parent pointer isn't specified at this line: the declaration of the parent is simply NULL, and not touched in this IOMMUFD_OBJ_IOAS case, as the parent pointer would be only specified in the IOMMUFD_OBJ_HW_PAGETABLE case that is behind this line.
I see your point. As long as the type is IOAS the alloc request is always interpreted as creating a s2 hwpt under the IOAS. Only when it's HWPT type then it's treated as the parent.
I kept a wrong impression that there is another flag/field to mark the parent requirement then there could be wrong combination of setting that flag/field plus using an IOAS pt_id. 😊