[Qemu-devel] [PATCH 09/19] cpu: add helper cpu_exists(), to check if CPU with specified id exists

[Igor Mammedov <imammedo@redhat.com>]

... it should be used only on slow path since it does recursive search
    on /machine QOM tree for objects of TYPE_CPU

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
v2:
  * s/get_firmware_id()/get_arch_id()/ rebase fixup
  * remove check for get_arch_id being NULL, since it's always defined
---
 include/qom/cpu.h | 10 ++++++++++
 qom/cpu.c         | 21 +++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index b376416..cd7c4b5 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -225,6 +225,16 @@ void run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data);
  */
 CPUState *qemu_get_cpu(int index);
 
+/**
+ * cpu_exists:
+ * @id - guest exposed CPU ID to lookup
+ *
+ * Search for CPU with specified ID.
+ *
+ * Returns: true - CPU is found, false - CPU isn't found
+ */
+bool cpu_exists(int64_t id);
+
 #ifndef CONFIG_USER_ONLY
 
 typedef void (*CPUInterruptHandler)(CPUState *, int);
diff --git a/qom/cpu.c b/qom/cpu.c
index 90cbd77..c850d27 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -25,6 +25,27 @@
 #include "qemu/notify.h"
 #include "sysemu/sysemu.h"
 
+static int cpu_exist_cb(Object *obj, void *opaque)
+{
+    int64_t id = *(int64_t *)opaque;
+    Object *cpu_obj = object_dynamic_cast(obj, TYPE_CPU);
+
+    if (cpu_obj) {
+        CPUState *cpu = CPU(cpu_obj);
+        CPUClass *klass = CPU_GET_CLASS(cpu);
+
+        if (klass->get_arch_id(cpu) == id) {
+            return 1;
+        }
+    }
+    return object_child_foreach(obj, cpu_exist_cb, opaque);
+}
+
+bool cpu_exists(int64_t id)
+{
+   return cpu_exist_cb(qdev_get_machine(), &id) ? true : false;
+}
+
 /* CPU hot-plug notifiers */
 static NotifierList cpu_added_notifiers =
     NOTIFIER_LIST_INITIALIZER(cpu_add_notifiers);
-- 
1.8.2