Re: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT_INVALIDATE

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On 2023/11/20 16:09, Tian, Kevin wrote:
From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
Sent: Friday, November 17, 2023 9:07 PM
+
+	hwpt = iommufd_hw_pagetable_get_nested(ucmd, cmd->hwpt_id);
+	if (IS_ERR(hwpt))
+		return PTR_ERR(hwpt);
+
+	rc = hwpt->domain->ops->cache_invalidate_user(hwpt->domain,
&data_array,
+						      &cmd-
out_driver_error_code);
+	cmd->req_num = data_array.entry_num;
+	if (iommufd_ucmd_respond(ucmd, sizeof(*cmd)))
+		return -EFAULT;
+	iommufd_put_object(&hwpt->obj);

the object is not put when ucmd response fails. It can be put right
after calling @cache_invalidate_user()

yes.

@@ -309,6 +309,7 @@ union ucmd_buffer {
  	struct iommu_hwpt_alloc hwpt;
  	struct iommu_hwpt_get_dirty_bitmap get_dirty_bitmap;
  	struct iommu_hwpt_set_dirty_tracking set_dirty_tracking;
+	struct iommu_hwpt_invalidate cache;

In alphabetic order this should be put before "hwpt_set_dirty"

yes.

  	struct iommu_ioas_alloc alloc;
  	struct iommu_ioas_allow_iovas allow_iovas;
  	struct iommu_ioas_copy ioas_copy;
@@ -348,6 +349,8 @@ static const struct iommufd_ioctl_op
iommufd_ioctl_ops[] = {
  		 struct iommu_hwpt_get_dirty_bitmap, data),
  	IOCTL_OP(IOMMU_HWPT_SET_DIRTY_TRACKING,
iommufd_hwpt_set_dirty_tracking,
  		 struct iommu_hwpt_set_dirty_tracking, __reserved),
+	IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,
+		 struct iommu_hwpt_invalidate, out_driver_error_code),

ditto

+/**
+ * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
+ * @size: sizeof(struct iommu_hwpt_invalidate)
+ * @hwpt_id: HWPT ID of a nested HWPT for cache invalidation

remove the first 'HWPT'

+ * @reqs_uptr: User pointer to an array having @req_num of cache
invalidation
+ *             requests. The request entries in the array are of fixed width
+ *             @req_len, and contain a user data structure for invalidation
+ *             request specific to the given hardware page table.
+ * @req_type: One of enum iommu_hwpt_data_type, defining the data
type of all
+ *            the entries in the invalidation request array. It should suit
+ *            with the data_type passed per the allocation of the hwpt pointed
+ *            by @hwpt_id.

"It should match the data_type given to the specified hwpt"

above comments are well received. :)

+ * @req_len: Length (in bytes) of a request entry in the request array
+ * @req_num: Input the number of cache invalidation requests in the array.
+ *           Output the number of requests successfully handled by kernel.
+ * @out_driver_error_code: Report a driver speicifc error code upon failure.
+ *                         It's optional, driver has a choice to fill it or
+ *                         not.

Being optional how does the user tell whether the code is filled or not?

seems like we need a flag for it. otherwise, a reserved special value is
required. or is it enough to just document it that this field is available
or not per the iommu_hw_info_type?

+ *
+ * Invalidate the iommu cache for user-managed page table. Modifications
on a
+ * user-managed page table should be followed by this operation to sync
cache.
+ * Each ioctl can support one or more cache invalidation requests in the
array
+ * that has a total size of @req_len * @req_num.
+ */
+struct iommu_hwpt_invalidate {
+	__u32 size;
+	__u32 hwpt_id;
+	__aligned_u64 reqs_uptr;
+	__u32 req_type;
+	__u32 req_len;
+	__u32 req_num;
+	__u32 out_driver_error_code;
+};

Probably 'data_uptr', 'data_type', "entry_len' and 'entry_num" read slightly
better.

sure.

--
Regards,
Yi Liu




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