plugins/api: split out time control helpers

These are only usable in system mode where we control the timer. For
user-mode make them NOPs.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250304222439.2035603-29-alex.bennee@linaro.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/plugins/api-system.c b/plugins/api-system.c
index 38560de342..cc190b167e 100644
--- a/plugins/api-system.c
+++ b/plugins/api-system.c
@@ -95,3 +95,37 @@ const char *qemu_plugin_hwaddr_device_name(const struct qemu_plugin_hwaddr *h)
         return g_intern_static_string("RAM");
     }
 }
+
+/*
+ * Time control
+ */
+static bool has_control;
+static Error *migration_blocker;
+
+const void *qemu_plugin_request_time_control(void)
+{
+    if (!has_control) {
+        has_control = true;
+        error_setg(&migration_blocker,
+                   "TCG plugin time control does not support migration");
+        migrate_add_blocker(&migration_blocker, NULL);
+        return &has_control;
+    }
+    return NULL;
+}
+
+static void advance_virtual_time__async(CPUState *cpu, run_on_cpu_data data)
+{
+    int64_t new_time = data.host_ulong;
+    qemu_clock_advance_virtual_time(new_time);
+}
+
+void qemu_plugin_update_ns(const void *handle, int64_t new_time)
+{
+    if (handle == &has_control) {
+        /* Need to execute out of cpu_exec, so bql can be locked. */
+        async_run_on_cpu(current_cpu,
+                         advance_virtual_time__async,
+                         RUN_ON_CPU_HOST_ULONG(new_time));
+    }
+}