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-rw-r--r--arch/s390/mm/gmap.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index c07d64f..4a1434b 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -1455,6 +1455,19 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
gmap_free(new);
return sg;
}
+ if (asce & _ASCE_REAL_SPACE) {
+ /* only allow one real-space gmap shadow */
+ list_for_each_entry(sg, &parent->children, list) {
+ if (sg->orig_asce & _ASCE_REAL_SPACE) {
+ spin_lock(&sg->guest_table_lock);
+ gmap_unshadow(sg);
+ spin_unlock(&sg->guest_table_lock);
+ list_del(&sg->list);
+ gmap_put(sg);
+ break;
+ }
+ }
+ }
atomic_set(&new->ref_count, 2);
list_add(&new->list, &parent->children);
if (asce & _ASCE_REAL_SPACE) {
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