qemu_timer.c: add timer_deadline_ms() helper

The pSeries machine is using QEMUTimer internals to return the timeout
in seconds for a timer object, in hw/ppc/spapr.c, function
spapr_drc_unplug_timeout_remaining_sec().

Create a helper in qemu-timer.c to retrieve the deadline for a QEMUTimer
object, in ms, to avoid exposing timer internals to the PPC code.

CC: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210301124133.23800-2-danielhb413@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_drc.c

@@ -421,9 +421,8 @@ void spapr_drc_unplug_request(SpaprDrc *drc)
 
 int spapr_drc_unplug_timeout_remaining_sec(SpaprDrc *drc)
 {
-    if (drc->unplug_requested && timer_pending(drc->unplug_timeout_timer)) {
-        return (qemu_timeout_ns_to_ms(drc->unplug_timeout_timer->expire_time) -
-                qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL)) / 1000;
+    if (drc->unplug_requested) {
+        return timer_deadline_ms(drc->unplug_timeout_timer) / 1000;
     }
 
     return 0;

include/qemu/timer.h

@@ -795,6 +795,14 @@ static inline int64_t get_max_clock_jump(void)
     return 60 * NANOSECONDS_PER_SECOND;
 }
 
+/**
+ * timer_deadline_ms:
+ *
+ * Returns the remaining miliseconds for @timer to expire, or zero
+ * if the timer is no longer pending.
+ */
+int64_t timer_deadline_ms(QEMUTimer *timer);
+
 /*
  * Low level clock functions
  */

util/qemu-timer.c

@@ -243,6 +243,19 @@ int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
     return delta;
 }
 
+/*
+ * Returns the time remaining for the deadline, in ms.
+ */
+int64_t timer_deadline_ms(QEMUTimer *timer)
+{
+    if (timer_pending(timer)) {
+        return qemu_timeout_ns_to_ms(timer->expire_time) -
+               qemu_clock_get_ms(timer->timer_list->clock->type);
+    }
+
+    return 0;
+}
+
 /* Calculate the soonest deadline across all timerlists attached
  * to the clock. This is used for the icount timeout so we
  * ignore whether or not the clock should be used in deadline