From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40520) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z3Pf3-0007eg-0r for qemu-devel@nongnu.org; Fri, 12 Jun 2015 10:10:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z3Pex-00047l-1t for qemu-devel@nongnu.org; Fri, 12 Jun 2015 10:10:20 -0400 Received: from lepton.topquark.net ([168.235.66.66]:54625 helo=Mail2.TopQuark.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z3Pew-00047h-V7 for qemu-devel@nongnu.org; Fri, 12 Jun 2015 10:10:14 -0400 Date: Fri, 12 Jun 2015 10:10:14 -0400 From: Paul Donohue Message-ID: <20150612141013.GE2749@TopQuark.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: [Qemu-devel] [PATCH 2/2] mc146818rtc: Reset the periodic timer on load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini When loading a VM from a snapshot or migration, clock changes can cause the periodic timer to stall or loop rapidly. qemu-timer has a reset notifier mechanism that is used to avoid timer stalls or loops if the host clock changes while the VM is running when using QEMU_CLOCK_HOST. However, when loading a snapshot or migration, qemu-timer is initialized and fires the reset notifier before mc146818rtc is initialized and has registered its reset handler. In addition, this mechanism isn't used when using QEMU_CLOCK_REALTIME, which might also change when loading a snapshot or migration. To correct that problem, this commit resets the periodic timer after loading from a snapshot or migration if the clock has either jumped backward or has jumped forward by more than the clock jump limit that is used by the reset notifier code in qemu-timer. Signed-off-by: Paul Donohue --- hw/timer/mc146818rtc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c index f2b77fa..68cf1f0 100644 --- a/hw/timer/mc146818rtc.c +++ b/hw/timer/mc146818rtc.c @@ -723,6 +723,12 @@ static int rtc_post_load(void *opaque, int version_id) check_update_timer(s); } + uint64_t now = qemu_clock_get_ns(rtc_clock); + if (now < (s->next_periodic_time - get_ticks_per_sec()) || + now > (s->next_periodic_time + get_max_clock_jump())) { + periodic_timer_update(s, qemu_clock_get_ns(rtc_clock)); + } + #ifdef TARGET_I386 if (version_id >= 2) { if (s->lost_tick_policy == LOST_TICK_POLICY_SLEW) { -- 2.1.4