Re: [PATCH v5 07/11] iommufd: Add data structure for Intel VT-d stage-1 cache invalidation

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On 2023/9/21 15:54, Yi Liu wrote:
This adds the data structure for flushing iotlb for the nested domain
allocated with IOMMU_HWPT_TYPE_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.

Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
  include/uapi/linux/iommufd.h | 34 ++++++++++++++++++++++++++++++++++
  1 file changed, 34 insertions(+)

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 18a502e206c3..3050efbceb57 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -510,6 +510,40 @@ struct iommu_hw_info {
  };
  #define IOMMU_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_GET_HW_INFO)
+/**
+ * enum iommu_hwpt_vtd_s1_invalidate_flags - Flags for Intel VT-d
+ *                                           stage-1 cache invalidation
+ * @IOMMU_VTD_QI_FLAGS_LEAF: The LEAF flag indicates whether only the
+ *                           leaf PTE caching needs to be invalidated
+ *                           and other paging structure caches can be
+ *                           preserved.
+ */
+enum iommu_hwpt_vtd_s1_invalidate_flags {
+	IOMMU_VTD_QI_FLAGS_LEAF = 1 << 0,
+};
+
+/**
+ * struct iommu_hwpt_vtd_s1_invalidate - Intel VT-d cache invalidation
+ *                                       (IOMMU_HWPT_TYPE_VTD_S1)
+ * @addr: The start address of the addresses to be invalidated.

Is there an alignment requirement for @addr? If so, is 4K alignment
sufficient? Perhaps we need to document it here so that user space can
calculate the @addr correctly.

+ * @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 under nested translation. Userspace uses this structure to
+ * tell host about the impacted caches 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).
+ */
+struct iommu_hwpt_vtd_s1_invalidate {
+	__aligned_u64 addr;
+	__aligned_u64 npages;
+	__u32 flags;
+	__u32 __reserved;
+};
+
  /**
   * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
   * @size: sizeof(struct iommu_hwpt_invalidate)

Best regards,
baolu



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