tests/tcg/plugins: add plugin to test reset and uninstall

We perform a plugin reset, uninstall, and make sure we went through
those steps.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20250404032027.430575-3-pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

tests/tcg/plugins/meson.build

@@ -1,6 +1,6 @@
 t = []
 if get_option('plugins')
-  foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'syscall']
+  foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'reset', 'syscall']
     if host_os == 'windows'
       t += shared_module(i, files(i + '.c') + '../../../contrib/plugins/win32_linker.c',
                         include_directories: '../../../include/qemu',

tests/tcg/plugins/reset.c

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2025 Linaro Ltd
+ *
+ * Test the reset/uninstall cycle of a plugin.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <glib.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+static qemu_plugin_id_t plugin_id;
+static bool was_reset;
+static bool was_uninstalled;
+
+static void after_uninstall(qemu_plugin_id_t id)
+{
+    g_assert(was_reset && !was_uninstalled);
+    qemu_plugin_outs("uninstall done\n");
+    was_uninstalled = true;
+}
+
+static void tb_exec_after_reset(unsigned int vcpu_index, void *userdata)
+{
+    g_assert(was_reset && !was_uninstalled);
+    qemu_plugin_uninstall(plugin_id, after_uninstall);
+}
+
+static void tb_trans_after_reset(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+    g_assert(was_reset && !was_uninstalled);
+    qemu_plugin_register_vcpu_tb_exec_cb(tb, tb_exec_after_reset,
+                                         QEMU_PLUGIN_CB_NO_REGS, NULL);
+}
+
+static void after_reset(qemu_plugin_id_t id)
+{
+    g_assert(!was_reset && !was_uninstalled);
+    qemu_plugin_outs("reset done\n");
+    was_reset = true;
+    qemu_plugin_register_vcpu_tb_trans_cb(id, tb_trans_after_reset);
+}
+
+static void tb_exec_before_reset(unsigned int vcpu_index, void *userdata)
+{
+    g_assert(!was_reset && !was_uninstalled);
+    qemu_plugin_reset(plugin_id, after_reset);
+}
+
+static void tb_trans_before_reset(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+    g_assert(!was_reset && !was_uninstalled);
+    qemu_plugin_register_vcpu_tb_exec_cb(tb, tb_exec_before_reset,
+                                         QEMU_PLUGIN_CB_NO_REGS, NULL);
+}
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+                                           const qemu_info_t *info,
+                                           int argc, char **argv)
+{
+    plugin_id = id;
+    qemu_plugin_register_vcpu_tb_trans_cb(id, tb_trans_before_reset);
+    return 0;
+}
+
+/* Since we uninstall the plugin, we can't use qemu_plugin_register_atexit_cb,
+ * so we use destructor attribute instead. */
+static void __attribute__((destructor)) on_plugin_exit(void)
+{
+    g_assert(was_reset && was_uninstalled);
+    qemu_plugin_outs("plugin exit\n");
+}