[RFC 12/41] hw/core/topo: Add helpers to traverse the CPU topology tree

[Zhao Liu <zhao1.liu@xxxxxxxxxxxxxxx>]

From: Zhao Liu <zhao1.liu@xxxxxxxxx>

The topology devices will be organized as a topology tree. Each topology
device may have many topology children with lower topology level.

Add the helpers to traverse the CPU topology tree.

Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
---
 hw/core/cpu-topo.c         | 41 ++++++++++++++++++++++++++++++++++++++
 include/hw/core/cpu-topo.h | 13 ++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/hw/core/cpu-topo.c b/hw/core/cpu-topo.c
index cba2dc747e74..687a4cc566ec 100644
--- a/hw/core/cpu-topo.c
+++ b/hw/core/cpu-topo.c
@@ -318,3 +318,44 @@ static void cpu_topo_register_types(void)
 }
 
 type_init(cpu_topo_register_types)
+
+static int do_cpu_topo_child_foreach(CPUTopoState *topo,
+                                     unsigned long *levels,
+                                     topo_fn fn, void *opaque,
+                                     bool recurse)
+{
+    CPUTopoState *child;
+    int ret = TOPO_FOREACH_CONTINUE;
+
+    QTAILQ_FOREACH(child, &topo->children, sibling) {
+        if (!levels || (levels && test_bit(CPU_TOPO_LEVEL(child), levels))) {
+            ret = fn(child, opaque);
+            if (ret == TOPO_FOREACH_END || ret == TOPO_FOREACH_ERR) {
+                break;
+            } else if (ret == TOPO_FOREACH_SIBLING) {
+                continue;
+            }
+        }
+
+        if (recurse) {
+            ret = do_cpu_topo_child_foreach(child, levels, fn, opaque, 
recurse);
+            if (ret != TOPO_FOREACH_CONTINUE) {
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+int cpu_topo_child_foreach(CPUTopoState *topo, unsigned long *levels,
+                           topo_fn fn, void *opaque)
+{
+    return do_cpu_topo_child_foreach(topo, levels, fn, opaque, false);
+}
+
+int cpu_topo_child_foreach_recursive(CPUTopoState *topo,
+                                     unsigned long *levels,
+                                     topo_fn fn, void *opaque)
+{
+    return do_cpu_topo_child_foreach(topo, levels, fn, opaque, true);
+}
diff --git a/include/hw/core/cpu-topo.h b/include/hw/core/cpu-topo.h
index 1ffdb0be6d38..453bacbb558b 100644
--- a/include/hw/core/cpu-topo.h
+++ b/include/hw/core/cpu-topo.h
@@ -90,4 +90,17 @@ struct CPUTopoState {
 
 #define CPU_TOPO_LEVEL(topo)    (CPU_TOPO_GET_CLASS(topo)->level)
 
+#define TOPO_FOREACH_SIBLING         2
+#define TOPO_FOREACH_END             1
+#define TOPO_FOREACH_CONTINUE        0
+#define TOPO_FOREACH_ERR             -1
+
+typedef int (*topo_fn)(CPUTopoState *topo, void *opaque);
+
+int cpu_topo_child_foreach(CPUTopoState *topo, unsigned long *levels,
+                           topo_fn fn, void *opaque);
+int cpu_topo_child_foreach_recursive(CPUTopoState *topo,
+                                     unsigned long *levels,
+                                     topo_fn fn, void *opaque);
+
 #endif /* CPU_TOPO_H */
-- 
2.34.1