[PATCH v1 03/16] iommu: Add iommu_copy_struct_to_user helper

Nicolin Chen
2025-04-11T06:38:29Z

Similar to the iommu_copy_struct_from_user helper receiving data from the
user space, add an iommu_copy_struct_to_user helper to report output data
back to the user space data pointer.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
include/linux/iommu.h | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ebde19aa3c28..ffb00054da33 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -562,6 +562,46 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size,
return 0;
}

+/**
+ * __iommu_copy_struct_to_user - Report iommu driver specific user space data
+ * @dst_data: Pointer to a struct iommu_user_data for user space data location
+ * @src_data: Pointer to an iommu driver specific user data that is defined in
+ * include/uapi/linux/iommufd.h
+ * @data_type: The data type of the @dst_data. Must match with @src_data.type
+ * @data_len: Length of current user data structure, i.e. sizeof(struct _src)
+ * @min_len: Initial length of user data structure for backward compatibility.
+ * This should be offsetofend using the last member in the user data
+ * struct that was initially added to include/uapi/linux/iommufd.h
+ */
+static inline int
+__iommu_copy_struct_to_user(const struct iommu_user_data *dst_data,
+ void *src_data, unsigned int data_type,
+ size_t data_len, size_t min_len)
+{
+ if (dst_data->type != data_type)
+ return -EINVAL;
+ if (WARN_ON(!dst_data || !src_data))
+ return -EINVAL;
+ if (dst_data->len < min_len || data_len < dst_data->len)
+ return -EINVAL;
+ return copy_struct_to_user(dst_data->uptr, dst_data->len, src_data,
+ data_len, NULL);
+}
+
+/**
+ * iommu_copy_struct_to_user - Report iommu driver specific user space data
+ * @user_data: Pointer to a struct iommu_user_data for user space data location
+ * @ksrc: Pointer to an iommu driver specific user data that is defined in
+ * include/uapi/linux/iommufd.h
+ * @data_type: The data type of the @ksrc. Must match with @user_data->type
+ * @min_last: The last memember of the data structure @ksrc points in the
+ * initial version.
+ * Return 0 for success, otherwise -error.
+ */
+#define iommu_copy_struct_to_user(user_data, ksrc, data_type, min_last) \
+ __iommu_copy_struct_to_user(user_data, ksrc, data_type, sizeof(*ksrc), \
+ offsetofend(typeof(*ksrc), min_last))
+
/**
* struct iommu_ops - iommu ops and capabilities
* @capable: check capability
--
2.43.0