[PATCH v6 3/6] iommu: Add iommu_copy_struct_from_user_array helper

[Yi Liu <yi.l.liu@intel.com>]

From: Nicolin Chen <nicolinc@nvidia.com>

Wrap up the data type/pointer/num sanity and __iommu_copy_struct_from_user
call for iommu drivers to copy driver specific data at a specific location
in the struct iommu_user_data_array.

And expect it to be used in cache_invalidate_user ops for example.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Co-developed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 include/linux/iommu.h | 54 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 0c1ff7fe4fa1..832fdf193c57 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -342,6 +342,60 @@ static inline int __iommu_copy_struct_from_user(
 				      sizeof(*kdst),                      \
 				      offsetofend(typeof(*kdst), min_last))
 
+/**
+ * __iommu_copy_struct_from_user_array - Copy iommu driver specific user space
+ *                                       data from an iommu_user_data_array
+ * @dst_data: Pointer to an iommu driver specific user data that is defined in
+ *            include/uapi/linux/iommufd.h
+ * @src_array: Pointer to a struct iommu_user_data_array for a user space array
+ * @data_type: The data type of the @dst_data. Must match with @src_array.type
+ * @index: Index to offset the location in the array to copy user data from
+ * @data_len: Length of current user data structure, i.e. sizeof(struct _dst)
+ * @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_from_user_array(void *dst_data,
+				    const struct iommu_user_data_array *src_array,
+				    unsigned int data_type, unsigned int index,
+				    size_t data_len, size_t min_len)
+{
+	struct iommu_user_data src_data;
+
+	if (src_array->type != data_type)
+		return -EINVAL;
+	if (WARN_ON(!src_array || index >= src_array->entry_num))
+		return -EINVAL;
+	if (!src_array->entry_num)
+		return -EINVAL;
+	src_data.uptr = src_array->uptr + src_array->entry_len * index;
+	src_data.len = src_array->entry_len;
+	src_data.type = src_array->type;
+
+	return __iommu_copy_struct_from_user(dst_data, &src_data, data_type,
+					     data_len, min_len);
+}
+
+/**
+ * iommu_copy_struct_from_user_array - Copy iommu driver specific user space
+ *                                     data from an iommu_user_data_array
+ * @kdst: Pointer to an iommu driver specific user data that is defined in
+ *        include/uapi/linux/iommufd.h
+ * @user_array: Pointer to a struct iommu_user_data_array for a user space array
+ * @data_type: The data type of the @kdst. Must match with @user_array->type
+ * @index: Index to offset the location in the array to copy user data from
+ * @min_last: The last memember of the data structure @kdst points in the
+ *            initial version.
+ * Return 0 for success, otherwise -error.
+ */
+#define iommu_copy_struct_from_user_array(kdst, user_array, data_type,   \
+					  index, min_last)               \
+	__iommu_copy_struct_from_user_array(kdst, user_array, data_type, \
+					    index, sizeof(*kdst),        \
+					    offsetofend(typeof(*kdst),   \
+							min_last))
+
 /**
  * struct iommu_ops - iommu ops and capabilities
  * @capable: check capability
-- 
2.34.1