David Vrabel
2013-Jun-19 15:25 UTC
[PATCH 4/4] x86/xen: sync the CMOS RTC as well as the Xen wallclock
From: David Vrabel <david.vrabel@citrix.com>
Adjustments to Xen''s persistent clock via update_persistent_clock()
don''t actually persist, as the Xen wallclock is a software only clock
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 the clock_was_set notifier and a new timer,
xen_set_wallclock() need not do this and dom0 can simply use the
native implementation.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
arch/x86/xen/time.c | 49 +++++++++++++++++++++++++++++++------------------
1 files changed, 31 insertions(+), 18 deletions(-)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index c4bb255..18a3db6 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -198,39 +198,50 @@ static void xen_get_wallclock(struct timespec *now)
static int xen_set_wallclock(const struct timespec *now)
{
+ return -1;
+}
+
+static void xen_wallclock_timer_func(unsigned long d);
+static DEFINE_TIMER(xen_wallclock_timer, xen_wallclock_timer_func, 0, 0);
+
+static void xen_sync_wallclock(void)
+{
+ struct timespec now;
struct xen_platform_op op;
- /* do nothing for domU */
- if (!xen_initial_domain())
- return -1;
+ now = current_kernel_time();
op.cmd = XENPF_settime;
- op.u.settime.secs = now->tv_sec;
- op.u.settime.nsecs = now->tv_nsec;
+ 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);
+ (void)HYPERVISOR_dom0_op(&op);
+
+ /*
+ * Use a timer to correct for any drift in the Xen
+ * wallclock.
+ *
+ * 11 minutes is the same period as sync_cmos_clock().
+ */
+ mod_timer(&xen_wallclock_timer, round_jiffies(jiffies + 11*60*HZ));
}
-
+
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;
+ xen_sync_wallclock();
+ return NOTIFY_OK;
}
static struct notifier_block xen_clock_was_set_notifier = {
.notifier_call = xen_clock_was_set_notify,
};
+static void xen_wallclock_timer_func(unsigned long d)
+{
+ xen_sync_wallclock();
+}
static struct clocksource xen_clocksource __read_mostly = {
.name = "xen",
@@ -509,7 +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
David Vrabel
2013-Jun-20 19:16 UTC
[PATCH 4/4] x86/xen: sync the CMOS RTC as well as the Xen wallclock
From: David Vrabel <david.vrabel@citrix.com>
Adjustments to Xen''s persistent clock via update_persistent_clock()
don''t actually persist, as the Xen wallclock is a software only clock
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 the clock_was_set notifier and a new timer,
xen_set_wallclock() need not do this and dom0 can simply use the
native implementation.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
arch/x86/xen/time.c | 48 +++++++++++++++++++++++++++++++-----------------
1 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index ad077ca..f3d09eb 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -198,38 +198,50 @@ static void xen_get_wallclock(struct timespec *now)
static int xen_set_wallclock(const struct timespec *now)
{
+ return -1;
+}
+
+static void xen_wallclock_timer_func(unsigned long d);
+static DEFINE_TIMER(xen_wallclock_timer, xen_wallclock_timer_func, 0, 0);
+
+static void xen_sync_wallclock(void)
+{
+ struct timespec now;
struct xen_platform_op op;
- /* do nothing for domU */
- if (!xen_initial_domain())
- return -1;
+ now = current_kernel_time();
op.cmd = XENPF_settime;
- op.u.settime.secs = now->tv_sec;
- op.u.settime.nsecs = now->tv_nsec;
+ 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);
+ (void)HYPERVISOR_dom0_op(&op);
+
+ /*
+ * Use a timer to correct for any drift in the Xen
+ * wallclock.
+ *
+ * 11 minutes is the same period as sync_cmos_clock().
+ */
+ mod_timer(&xen_wallclock_timer, round_jiffies(jiffies + 11*60*HZ));
}
-
+
static int xen_clock_was_set_notify(struct notifier_block *nb, unsigned long
unused,
void *priv)
{
- struct timespec now;
-
- /*
- * Set the Xen wallclock from Linux system time.
- */
- now = current_kernel_time();
- xen_set_wallclock(&now);
-
- return NOTIFY_OK;
+ xen_sync_wallclock();
+ return NOTIFY_OK;
}
static struct notifier_block xen_clock_was_set_notifier = {
.notifier_call = xen_clock_was_set_notify,
};
+static void xen_wallclock_timer_func(unsigned long d)
+{
+ xen_sync_wallclock();
+}
static struct clocksource xen_clocksource __read_mostly = {
.name = "xen",
@@ -507,7 +519,9 @@ 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