iommu: Add iommu_copy_struct_to_user helper

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.

Link: https://patch.msgid.link/r/fa292c2a730aadd77085ec3a8272360c96eabb9c.1752126748.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b87c2841e6bc150cfa8dff18cf7bc68c3bbb3dc6..fd7319706684a074a89946268336eb2d84c41ba5 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -558,6 +558,46 @@ 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 @src_data. Must match with @dst_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 (WARN_ON(!dst_data || !src_data))
+               return -EINVAL;
+       if (dst_data->type != data_type)
+               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 member 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