[PATCH v2 09/12] plugins: add migration blocker

["Alex Bennée" <alex.bennee@linaro.org>]

If the plugin in controlling time there is some state that might be
missing from the plugin tracking it. Migration is unlikely to work in
this case so lets put a migration blocker in to let the user know if
they try.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Suggested-by: "Dr. David Alan Gilbert" <dave@treblig.org>
---
 plugins/api.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/plugins/api.c b/plugins/api.c
index 4431a0ea7e..c4239153af 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -47,6 +47,8 @@
 #include "disas/disas.h"
 #include "plugin.h"
 #ifndef CONFIG_USER_ONLY
+#include "qapi/error.h"
+#include "migration/blocker.h"
 #include "exec/ram_addr.h"
 #include "qemu/plugin-memory.h"
 #include "hw/boards.h"
@@ -589,11 +591,17 @@ uint64_t qemu_plugin_u64_sum(qemu_plugin_u64 entry)
  * Time control
  */
 static bool has_control;
+Error *migration_blocker;
 
 const void *qemu_plugin_request_time_control(void)
 {
     if (!has_control) {
         has_control = true;
+#ifdef CONFIG_SOFTMMU
+        error_setg(&migration_blocker,
+                   "TCG plugin time control does not support migration");
+        migrate_add_blocker(&migration_blocker, NULL);
+#endif
         return &has_control;
     }
     return NULL;
-- 
2.39.2