17 Mar
2023
17 Mar
'23
10:20 a.m.
From: Nicolin Chen nicolinc@nvidia.com Sent: Friday, March 17, 2023 12:02 PM
On Fri, Mar 17, 2023 at 03:02:26AM +0000, Tian, Kevin wrote:
+/**
- struct iommu_hwpt_alloc - ioctl(IOMMU_HWPT_ALLOC)
- @size: sizeof(struct iommu_hwpt_alloc)
- @flags: Must be 0
- @dev_id: The device to allocate this HWPT for
- @pt_id: The IOAS to connect this HWPT to
- @out_hwpt_id: The ID of the new HWPT
- @__reserved: Must be 0
- Explicitly allocate a hardware page table object. This is the same
object
- type that is returned by iommufd_device_attach() and represents the
- underlying iommu driver's iommu_domain kernel object.
- A normal HWPT will be created with the mappings from the given
IOAS.
- */
'normal' is a confusing word in this context.
Yea, Eric was asking about a related question in another thread, because he couldn't get this part. I think we could replace this "normal" with just "kernel-managed", so eventually it would look like the following narrative after adding user_data and nesting:
- A kernel-managed HWPT will be created with the mappings from the given
IOAS.
- The @data_type for its allocation can be set to
IOMMU_HWPT_TYPE_DEFAULT, or
- another type (being listed below) to customize the allocation.
- A user-managed HWPT will be created from a given parent HWPT via
@pt_id, in
- which the parent HWPT must be allocated previously via the same ioctl
from a
- given IOAS. The @data_type must not be set to
IOMMU_HWPT_TYPE_DEFAULT but a
- pre-defined type corresponding to the underlying IOMMU hardware.
that is fine. But at this point it's clearer to simply remove 'normal'. 😊