[PATCH 4/6] xen/gnttab: Document how _cache_flush() works

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Roger Pau Monné <roger@xxxxxxxxxxxxxx>
CC: Teddy Astie <teddy.astie@xxxxxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
CC: Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>
---
 xen/common/grant_table.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index f4ec7524140a..4cc23f9231e6 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -3598,6 +3598,15 @@ 
gnttab_swap_grant_ref(XEN_GUEST_HANDLE_PARAM(gnttab_swap_grant_ref_t) uop,
 }
 
 #ifdef CONFIG_HAS_GRANT_CACHE_FLUSH
+/*
+ * Issue a cache flush operation on memory owned by the domain, or a mapped
+ * grant from another domain.  The caller must pass in cur_ref = 0 initially,
+ * and preserve the value across continuations.
+ *
+ * Returns: 0 for success
+ *          1 for a continuation while searching the mapped grants
+ *     -errno for error
+ */
 static int _cache_flush(gnttab_cache_flush_t *cflush, grant_ref_t *cur_ref)
 {
     struct domain *d, *owner;
-- 
2.39.5