RE: [PATCH v7 1/3] iommufd: Add data structure for Intel VT-d stage-1 cache invalidation

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Friday, November 17, 2023 9:18 PM
> 
> This adds the data structure for flushing iotlb for the nested domain
> allocated with IOMMU_HWPT_DATA_VTD_S1 type.
> 
> This only supports invalidating IOTLB, but no for device-TLB as device-TLB
> invalidation will be covered automatically in the IOTLB invalidation if the
> underlying IOMMU driver has enabled ATS for the affected device.

"no for device-TLB" is misleading. Here just say that cache invalidation
request applies to both IOTLB and device TLB (if ATS is enabled ...)

> 
> +/**
> + * enum iommu_hwpt_vtd_s1_invalidate_flags - Flags for Intel VT-d
> + *                                           stage-1 cache invalidation
> + * @IOMMU_VTD_INV_FLAGS_LEAF: The LEAF flag indicates whether only
> the
> + *                            leaf PTE caching needs to be invalidated
> + *                            and other paging structure caches can be
> + *                            preserved.

remove the words after 'and'

> +
> +/**
> + * struct iommu_hwpt_vtd_s1_invalidate - Intel VT-d cache invalidation
> + *                                       (IOMMU_HWPT_DATA_VTD_S1)
> + * @addr: The start address of the addresses to be invalidated. It needs
> + *        to be 4KB aligned.

remove "of the addresses"

> + * @npages: Number of contiguous 4K pages to be invalidated.
> + * @flags: Combination of enum iommu_hwpt_vtd_s1_invalidate_flags
> + * @__reserved: Must be 0
> + *
> + * The Intel VT-d specific invalidation data for user-managed stage-1 cache
> + * invalidation in nested translation. Userspace uses this structure to
> + * tell the impacted cache scope after modifying the stage-1 page table.
> + *
> + * Invalidating all the caches related to the page table by setting @addr
> + * to be 0 and @npages to be __aligned_u64(-1). This includes the
> + * corresponding device-TLB if ATS is enabled on the attached devices.

put words about device-TLB to last paragraph. Putting it here is confusing
as if it only applies to invalidate-all.