util: add iova_tree_find_iova

This function does the reverse operation of iova_tree_find: To look for
a mapping that match a translated address so we can do the reverse.

This have linear complexity instead of logarithmic, but it supports
overlapping HVA. Future developments could reduce it.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/util/iova-tree.c b/util/iova-tree.c
index 139626b46f..6dff29c1f6 100644
--- a/util/iova-tree.c
+++ b/util/iova-tree.c
@@ -37,6 +37,11 @@ struct IOVATreeAllocArgs {
     bool iova_found;
 };
 
+typedef struct IOVATreeFindIOVAArgs {
+    const DMAMap *needle;
+    const DMAMap *result;
+} IOVATreeFindIOVAArgs;
+
 /**
  * Iterate args to the next hole
  *
@@ -81,6 +86,35 @@ const DMAMap *iova_tree_find(const IOVATree *tree, const DMAMap *map)
     return g_tree_lookup(tree->tree, map);
 }
 
+static gboolean iova_tree_find_address_iterator(gpointer key, gpointer value,
+                                                gpointer data)
+{
+    const DMAMap *map = key;
+    IOVATreeFindIOVAArgs *args = data;
+    const DMAMap *needle;
+
+    g_assert(key == value);
+
+    needle = args->needle;
+    if (map->translated_addr + map->size < needle->translated_addr ||
+        needle->translated_addr + needle->size < map->translated_addr) {
+        return false;
+    }
+
+    args->result = map;
+    return true;
+}
+
+const DMAMap *iova_tree_find_iova(const IOVATree *tree, const DMAMap *map)
+{
+    IOVATreeFindIOVAArgs args = {
+        .needle = map,
+    };
+
+    g_tree_foreach(tree->tree, iova_tree_find_address_iterator, &args);
+    return args.result;
+}
+
 const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova)
 {
     const DMAMap map = { .iova = iova, .size = 0 };