[RFC PATCH 29/31] sysemu: generalise qtest_warp_clock as qemu_clock_advance_virtual_time

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

Move the key functionality of moving time forward into the clock
sub-system itself. This will allow us to plumb in time control into
plugins.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230519170454.2353945-7-alex.bennee@linaro.org>

---
v2
  - rename arg to target_ns
---
 include/qemu/timer.h | 15 +++++++++++++++
 softmmu/qtest.c      | 24 ++----------------------
 util/qemu-timer.c    | 26 ++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 9a91cb1248..aa30f693b0 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -245,6 +245,21 @@ bool qemu_clock_run_timers(QEMUClockType type);
  */
 bool qemu_clock_run_all_timers(void);
 
+/**
+ * qemu_clock_advance_virtual_time(): advance the virtual time tick
+ * @target_ns: target time in nanoseconds
+ *
+ * This function is used where the control of the flow of time has
+ * been delegated to outside the clock subsystem (be it qtest, icount
+ * or some other external source). You can ask the clock system to
+ * return @early at the first expired timer.
+ *
+ * Time can only move forward, attempts to reverse time would lead to
+ * an error.
+ *
+ * Returns: new virtual time.
+ */
+int64_t qemu_clock_advance_virtual_time(int64_t target_ns);
 
 /*
  * QEMUTimerList
diff --git a/softmmu/qtest.c b/softmmu/qtest.c
index bac1962efb..72a2ee7a31 100644
--- a/softmmu/qtest.c
+++ b/softmmu/qtest.c
@@ -336,26 +336,6 @@ void qtest_set_virtual_clock(int64_t count)
     qatomic_set_i64(&qtest_clock_counter, count);
 }
 
-static void qtest_clock_warp(int64_t dest)
-{
-    int64_t clock = cpus_get_virtual_clock();
-    AioContext *aio_context;
-    assert(qtest_enabled());
-    aio_context = qemu_get_aio_context();
-    while (clock < dest) {
-        int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
-                                                      QEMU_TIMER_ATTR_ALL);
-        int64_t warp = qemu_soonest_timeout(dest - clock, deadline);
-
-        cpus_set_virtual_clock(cpus_get_virtual_clock() + warp);
-
-        qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
-        timerlist_run_timers(aio_context->tlg.tl[QEMU_CLOCK_VIRTUAL]);
-        clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
-    }
-    qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
-}
-
 static bool (*process_command_cb)(CharBackend *chr, gchar **words);
 
 void qtest_set_command_cb(bool (*pc_cb)(CharBackend *chr, gchar **words))
@@ -754,7 +734,7 @@ static void qtest_process_command(CharBackend *chr, gchar **words)
             ns = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
                                             QEMU_TIMER_ATTR_ALL);
         }
-        qtest_clock_warp(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns);
+        qemu_clock_advance_virtual_time(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns);
         qtest_send_prefix(chr);
         qtest_sendf(chr, "OK %"PRIi64"\n",
                     (int64_t)qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
@@ -780,7 +760,7 @@ static void qtest_process_command(CharBackend *chr, gchar **words)
         g_assert(words[1]);
         ret = qemu_strtoi64(words[1], NULL, 0, &ns);
         g_assert(ret == 0);
-        qtest_clock_warp(ns);
+        qemu_clock_advance_virtual_time(ns);
         qtest_send_prefix(chr);
         qtest_sendf(chr, "OK %"PRIi64"\n",
                     (int64_t)qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
diff --git a/util/qemu-timer.c b/util/qemu-timer.c
index 6a0de33dd2..213114be68 100644
--- a/util/qemu-timer.c
+++ b/util/qemu-timer.c
@@ -645,6 +645,11 @@ int64_t qemu_clock_get_ns(QEMUClockType type)
     }
 }
 
+static void qemu_virtual_clock_set_ns(int64_t time)
+{
+    return cpus_set_virtual_clock(time);
+}
+
 void init_clocks(QEMUTimerListNotifyCB *notify_cb)
 {
     QEMUClockType type;
@@ -675,3 +680,24 @@ bool qemu_clock_run_all_timers(void)
 
     return progress;
 }
+
+int64_t qemu_clock_advance_virtual_time(int64_t dest)
+{
+    int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    AioContext *aio_context;
+    aio_context = qemu_get_aio_context();
+    while (clock < dest) {
+        int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                                      QEMU_TIMER_ATTR_ALL);
+        int64_t warp = qemu_soonest_timeout(dest - clock, deadline);
+
+        qemu_virtual_clock_set_ns(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + warp);
+
+        qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
+        timerlist_run_timers(aio_context->tlg.tl[QEMU_CLOCK_VIRTUAL]);
+        clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    }
+    qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
+
+    return clock;
+}
-- 
2.39.2