From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757060Ab3FSPZy (ORCPT ); Wed, 19 Jun 2013 11:25:54 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:50898 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757043Ab3FSPZw (ORCPT ); Wed, 19 Jun 2013 11:25:52 -0400 X-IronPort-AV: E=Sophos;i="4.87,898,1363132800"; d="scan'208";a="30603447" From: David Vrabel To: CC: David Vrabel , Konrad Rzeszutek Wilk , , John Stultz , Thomas Gleixner Subject: [PATCH 3/4] x86/xen: sync the wallclock when the system time is stepped Date: Wed, 19 Jun 2013 16:25:22 +0100 Message-ID: <1371655523-15609-4-git-send-email-david.vrabel@citrix.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1371655523-15609-1-git-send-email-david.vrabel@citrix.com> References: <1371655523-15609-1-git-send-email-david.vrabel@citrix.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Vrabel The Xen wallclock is a software only clock within the Xen hypervisor that is used by: a) PV guests as the equivalent of a hardware RTC; and b) the hypervisor as the clock source for the emulated RTC provided to HVM guests. Currently the Xen wallclock is only updated every 11 minutes if NTP is synchronized to its clock source. If a guest is started before NTP is synchronized it may see an incorrect wallclock time. Use the clock_was_set notifier chain to receive a notification when the system time is stepped and update the wallclock to match the current system time. Signed-off-by: David Vrabel --- arch/x86/xen/time.c | 24 ++++++++++++++++++++++++ 1 files changed, 24 insertions(+), 0 deletions(-) diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index a1947ac..c4bb255 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -211,6 +211,26 @@ static int xen_set_wallclock(const struct timespec *now) return HYPERVISOR_dom0_op(&op); } + +static int xen_clock_was_set_notify(struct notifier_block *nb, unsigned long unused, + void *priv) +{ + struct timespec now; + int ret; + + /* + * Set the Xen wallclock from Linux system time. + */ + now = current_kernel_time(); + xen_set_wallclock(&now); + + return NOTIFY_OK; +} + +static struct notifier_block xen_clock_was_set_notifier = { + .notifier_call = xen_clock_was_set_notify, +}; + static struct clocksource xen_clocksource __read_mostly = { .name = "xen", @@ -473,6 +493,10 @@ static void __init xen_time_init(void) xen_setup_runstate_info(cpu); xen_setup_timer(cpu); xen_setup_cpu_clockevents(); + + if (xen_initial_domain()) + atomic_notifier_chain_register(&clock_was_set_notifier_list, + &xen_clock_was_set_notifier); } void __init xen_init_time_ops(void) -- 1.7.2.5