Re: [PATCH v3 08/17] iommufd: IOMMU_HWPT_ALLOC allocation with user data

On Fri, Jul 28, 2023 at 02:55:57PM -0300, Jason Gunthorpe wrote:

On Mon, Jul 24, 2023 at 04:03:57AM -0700, Yi Liu wrote:

...

• switch (pt_obj->type) {
• case IOMMUFD_OBJ_IOAS:

• ioas = container_of(pt_obj, struct iommufd_ioas, obj);
  

• break;
  

• case IOMMUFD_OBJ_HW_PAGETABLE:

• /* pt_id points HWPT only when hwpt_type is !IOMMU_HWPT_TYPE_DEFAULT */
  

• if (cmd->hwpt_type == IOMMU_HWPT_TYPE_DEFAULT) {
  

• 	rc = -EINVAL;
  

• 	goto out_put_pt;
  

• }
  

• parent = container_of(pt_obj, struct iommufd_hw_pagetable, obj);
  

• /*
  

•  * Cannot allocate user-managed hwpt linking to auto_created
  

•  * hwpt. If the parent hwpt is already a user-managed hwpt,
  

•  * don't allocate another user-managed hwpt linking to it.
  

•  */
  

• if (parent->auto_domain || parent->parent) {
  

• 	rc = -EINVAL;
  

• 	goto out_put_pt;
  

• }
  

• ioas = parent->ioas;
  

Why do we set ioas here? I would think it should be NULL.

I think it is looking like a mistake to try and re-use iommufd_hw_pagetable_alloc() directly for the nested case. It should not have a IOAS argument, it should not do enforce_cc, or iopt_* functions

So must of the function is removed. Probably better to make a new ioas-less function for the nesting case.

OK.

@Yi, along with the PATCH-6 (IOMMU_RESV_SW_MSI), I will rework on this -- mainly breaking up NESTED hwpt with IOAS.

Thanks Nic