Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/include/public/grant_table.h
+++ b/xen/include/public/grant_table.h
@@ -411,12 +411,13 @@ typedef struct gnttab_dump_table gnttab_
 DEFINE_XEN_GUEST_HANDLE(gnttab_dump_table_t);
 
 /*
- * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
- * foreign domain has previously registered its interest in the transfer via
- * <domid, ref>.
+ * GNTTABOP_transfer: Transfer <frame> to a foreign domain. The foreign domain
+ * has previously registered its interest in the transfer via <domid, ref>.
  *
  * Note that, even if the transfer fails, the specified page no longer belongs
  * to the calling domain *unless* the error is GNTST_bad_page.
+ *
+ * Note further that only PV guests can use this operation.
  */
 struct gnttab_transfer {
     /* IN parameters. */
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -102,6 +102,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_memory_reser
  * Returns zero on complete success, otherwise a negative error code.
  * On complete success then always @nr_exchanged == @in.nr_extents.
  * On partial success @nr_exchanged indicates how much work was done.
+ *
+ * Note that only PV guests can use this operation.
  */
 #define XENMEM_exchange             11
 struct xen_memory_exchange {