xen: mapcache: Unmap first entries in buckets

When invalidating memory ranges, if we happen to hit the first
entry in a bucket we were never unmapping it. This was harmless
for foreign mappings but now that we're looking to reuse the
mapcache for transient grant mappings, we must unmap entries
when invalidated.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
index bc860f4..ec95445 100644
--- a/hw/xen/xen-mapcache.c
+++ b/hw/xen/xen-mapcache.c
@@ -491,18 +491,23 @@ static void xen_invalidate_map_cache_entry_unlocked(MapCache *mc,
         return;
     }
     entry->lock--;
-    if (entry->lock > 0 || pentry == NULL) {
+    if (entry->lock > 0) {
         return;
     }
 
-    pentry->next = entry->next;
     ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size);
     if (munmap(entry->vaddr_base, entry->size) != 0) {
         perror("unmap fails");
         exit(-1);
     }
+
     g_free(entry->valid_mapping);
-    g_free(entry);
+    if (pentry) {
+        pentry->next = entry->next;
+        g_free(entry);
+    } else {
+        memset(entry, 0, sizeof *entry);
+    }
 }
 
 typedef struct XenMapCacheData {