tcg plugins: expose an API version concept

This is a very simple versioning API which allows the plugin
infrastructure to check the API a plugin was built against. We also
expose a min/cur API version to the plugin via the info block in case
it wants to avoid using old deprecated APIs in the future.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Robert Foley <robert.foley@linaro.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index a00a7deb46..5502e112c8 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -38,9 +38,28 @@
 
 typedef uint64_t qemu_plugin_id_t;
 
+/*
+ * Versioning plugins:
+ *
+ * The plugin API will pass a minimum and current API version that
+ * QEMU currently supports. The minimum API will be incremented if an
+ * API needs to be deprecated.
+ *
+ * The plugins export the API they were built against by exposing the
+ * symbol qemu_plugin_version which can be checked.
+ */
+
+extern QEMU_PLUGIN_EXPORT int qemu_plugin_version;
+
+#define QEMU_PLUGIN_VERSION 0
+
 typedef struct {
     /* string describing architecture */
     const char *target_name;
+    struct {
+        int min;
+        int cur;
+    } version;
     /* is this a full system emulation? */
     bool system_emulation;
     union {