From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: [PATCH 2/2] x86/xen: sync the CMOS RTC as well as the Xen wallclock Date: Thu, 30 May 2013 15:25:19 +0100 Message-ID: <1369923919-26981-3-git-send-email-david.vrabel__6881.32481086559$1369924058$gmane$org@citrix.com> References: <1369923919-26981-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1369923919-26981-1-git-send-email-david.vrabel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org, John Stultz , David Vrabel , Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org From: David Vrabel Adjustments to Xen's persistent_clock via update_persistent_clock() don't actually persist, as the Xen wallclock is just used by domU guests, and modifications to it do not modify the underlying CMOS RTC. The x86_platform.set_wallclock hook can be used to keep the hardware RTC synchronized (as on bare metal). Because the Xen wallclock is now kept synchronized by xen_pvclock_gtod_notify() on any system time change, xen_set_wallclock() need not do this and dom0 can simply use the native implementation. Signed-off-by: David Vrabel --- arch/x86/xen/time.c | 17 ++++------------- 1 files changed, 4 insertions(+), 13 deletions(-) diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 60b7d1f..0e69994 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -199,18 +199,7 @@ static void xen_get_wallclock(struct timespec *now) static int xen_set_wallclock(const struct timespec *now) { - struct xen_platform_op op; - - /* do nothing for domU */ - if (!xen_initial_domain()) - return -1; - - op.cmd = XENPF_settime; - op.u.settime.secs = now->tv_sec; - op.u.settime.nsecs = now->tv_nsec; - op.u.settime.system_time = xen_clocksource_read(); - - return HYPERVISOR_dom0_op(&op); + return -1; } static int xen_pvclock_gtod_notify(struct notifier_block *nb, unsigned long unused, @@ -531,7 +520,9 @@ void __init xen_init_time_ops(void) x86_platform.calibrate_tsc = xen_tsc_khz; x86_platform.get_wallclock = xen_get_wallclock; - x86_platform.set_wallclock = xen_set_wallclock; + /* Dom0 uses the native method to set the hardware RTC. */ + if (!xen_initial_domain()) + x86_platform.set_wallclock = xen_set_wallclock; } #ifdef CONFIG_XEN_PVHVM -- 1.7.2.5