plugins: add time control API

Expose the ability to control time through the plugin API. Only one
plugin can control time so it has to request control when loaded.
There are probably more corner cases to catch here.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
[AJB: tweaked user-mode handling, merged QEMU_PLUGIN_API fix]
Message-Id: <20240530220610.1245424-6-pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240620152220.2192768-9-alex.bennee@linaro.org>

diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 95703d8fec1ad859355433a35f08770e2504c829..c71c705b699f077e4cf65f7c1e86f4f02586eea8 100644 (file)
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -661,6 +661,33 @@ void qemu_plugin_register_vcpu_mem_inline_per_vcpu(
     qemu_plugin_u64 entry,
     uint64_t imm);
 
+/**
+ * qemu_plugin_request_time_control() - request the ability to control time
+ *
+ * This grants the plugin the ability to control system time. Only one
+ * plugin can control time so if multiple plugins request the ability
+ * all but the first will fail.
+ *
+ * Returns an opaque handle or NULL if fails
+ */
+QEMU_PLUGIN_API
+const void *qemu_plugin_request_time_control(void);
+
+/**
+ * qemu_plugin_update_ns() - update system emulation time
+ * @handle: opaque handle returned by qemu_plugin_request_time_control()
+ * @time: time in nanoseconds
+ *
+ * This allows an appropriately authorised plugin (i.e. holding the
+ * time control handle) to move system time forward to @time. For
+ * user-mode emulation the time is not changed by this as all reported
+ * time comes from the host kernel.
+ *
+ * Start time is 0.
+ */
+QEMU_PLUGIN_API
+void qemu_plugin_update_ns(const void *handle, int64_t time);
+
 typedef void
 (*qemu_plugin_vcpu_syscall_cb_t)(qemu_plugin_id_t id, unsigned int vcpu_index,
                                  int64_t num, uint64_t a1, uint64_t a2,

diff --git a/plugins/api.c b/plugins/api.c
index 6bdb26bbe3425b3e69feb0b260fe1f4a2b51a53f..4431a0ea7ee9971ea99b8d3ad4c273cbbaa89342 100644 (file)
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -39,6 +39,7 @@
 #include "qemu/main-loop.h"
 #include "qemu/plugin.h"
 #include "qemu/log.h"
+#include "qemu/timer.h"
 #include "tcg/tcg.h"
 #include "exec/exec-all.h"
 #include "exec/gdbstub.h"
@@ -583,3 +584,37 @@ uint64_t qemu_plugin_u64_sum(qemu_plugin_u64 entry)
     }
     return total;
 }
+
+/*
+ * Time control
+ */
+static bool has_control;
+
+const void *qemu_plugin_request_time_control(void)
+{
+    if (!has_control) {
+        has_control = true;
+        return &has_control;
+    }
+    return NULL;
+}
+
+#ifdef CONFIG_SOFTMMU
+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);
+}
+#endif
+
+void qemu_plugin_update_ns(const void *handle, int64_t new_time)
+{
+#ifdef CONFIG_SOFTMMU
+    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));
+    }
+#endif
+}

diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols
index aa0a77a319f572da863e440cd8903ff0fd8e4b7d..ca773d8d9fe1966293904bd35dbb0d2a19483de4 100644 (file)
--- a/plugins/qemu-plugins.symbols
+++ b/plugins/qemu-plugins.symbols
@@ -38,6 +38,7 @@
   qemu_plugin_register_vcpu_tb_exec_cond_cb;
   qemu_plugin_register_vcpu_tb_exec_inline_per_vcpu;
   qemu_plugin_register_vcpu_tb_trans_cb;
+  qemu_plugin_request_time_control;
   qemu_plugin_reset;
   qemu_plugin_scoreboard_free;
   qemu_plugin_scoreboard_find;
@@ -51,5 +52,6 @@
   qemu_plugin_u64_set;
   qemu_plugin_u64_sum;
   qemu_plugin_uninstall;
+  qemu_plugin_update_ns;
   qemu_plugin_vcpu_for_each;
 };