Re: [PATCH v5 10/11] iommu/vt-d: Add nested domain allocation

On 2023/9/27 14:56, Tian, Kevin wrote:

...

From: Liu, Yi L yi.l.liu@intel.com Sent: Thursday, September 21, 2023 3:55 PM

• if (hwpt_type != IOMMU_HWPT_TYPE_DEFAULT &&

•    hwpt_type != IOMMU_HWPT_TYPE_VTD_S1)
  

• return ERR_PTR(-EINVAL);
  

• if ((hwpt_type == IOMMU_HWPT_TYPE_DEFAULT) == !!parent)

• return ERR_PTR(-EINVAL);
  

this is probably too strict. What about intel-iommu driver supports a IOMMU_HWPT_TYPE_VTD_S2 later for some tweak w/o nesting?

in that case, this check needs to be updated

let's make the parent match specific to VTD_S1 type.

ok. how about below?

if ((data_type == IOMMU_HWPT_ALLOC_DATA_VTD_S1) && !parent)

...

• if (parent && request_nest_parent)

• return ERR_PTR(-EINVAL);
  

this check should be moved to iommufd?

oops, maybe no need, iommufd_hwpt_alloc() has below check.

if (cmd->flags & IOMMU_HWPT_ALLOC_NEST_PARENT && cmd->data_type != IOMMU_HWPT_ALLOC_DATA_NONE) return -EINVAL;