RE: [PATCH v8 09/10] iommufd: Add data structure for Intel VT-d stage-1 cache invalidation

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Thursday, December 28, 2023 12:14 AM
> +/**
> + * struct iommu_hwpt_vtd_s1_invalidate - Intel VT-d cache invalidation
> + *                                       (IOMMU_HWPT_INVALIDATE_DATA_VTD_S1)
> + * @addr: The start address of the range to be invalidated. It needs to
> + *        be 4KB aligned.
> + * @npages: Number of contiguous 4K pages to be invalidated.
> + * @flags: Combination of enum iommu_hwpt_vtd_s1_invalidate_flags
> + * @hw_error: One of enum iommu_hwpt_vtd_s1_invalidate_error
> + *
> + * 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 U64_MAX.
> + *
> + * The device TLB will be invalidated automatically if ATS is enabled.
> + *
> + * The @hw_error is meaningful when the entry is handled by the kernel.
> + * Check the entry_num output of IOMMU_HWPT_INVALIDATE ioctl to
> know the
> + * handled entries. @hw_error only covers the errors detected by hardware.
> + * The software detected errors would go through the normal ioctl errno.
> + */

* An entry is considered 'handled' after it passes the audit and submitted
* to the IOMMU by the underlying driver. Check the @entry_num output of
* struct iommu_hwpt_invalidate for the number of handled entries. A 'handled'
* request may still fail in hardware for various reasons, e.g. due to timeout
* on waiting for device response upon a device TLB invalidation request. In
* such case the hardware error info is reported in the @hw_error field of the
* handled entry.