Stefano Stabellini
2010-Feb-09 20:10 UTC
[Xen-devel] [PATCH] [PVOPS] [UPDATE] dom0 sync xen wallclock
Hi Jeremy,
this patch removes clock_was_set and adds an atomic notification chain
instead so that not only hrtimers but other parts of the kernel can be
notified of a time change as well.
In fact xen/time.c needs to be notified so that can update xen
wallclock time to keep it in sync; this is necessary otherwise other
PV guests will get a wrong wallclock time at boot.
This updated version contains more clock_was_set substitutions for
architectures other than x86.
Please let me know if my approach is suitable for upstream, I am willing
to do any change needed and to send the patch upstream myself if you
give me some directions.
Cheers,
Stefano
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index b04e2cb..7615696 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -497,7 +497,7 @@ do_settimeofday(struct timespec *tv)
ntp_clear();
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index 4cdc4a0..2bb7e6f 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -287,7 +287,7 @@ int do_settimeofday(struct timespec *tv)
ntp_clear();
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
diff --git a/arch/blackfin/kernel/time.c b/arch/blackfin/kernel/time.c
index adb54aa..521263f 100644
--- a/arch/blackfin/kernel/time.c
+++ b/arch/blackfin/kernel/time.c
@@ -236,7 +236,7 @@ int do_settimeofday(struct timespec *tv)
ntp_clear();
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
diff --git a/arch/cris/kernel/time.c b/arch/cris/kernel/time.c
index 074fe7d..ff9fad8 100644
--- a/arch/cris/kernel/time.c
+++ b/arch/cris/kernel/time.c
@@ -104,7 +104,7 @@ int do_settimeofday(struct timespec *tv)
ntp_clear();
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
diff --git a/arch/m32r/kernel/time.c b/arch/m32r/kernel/time.c
index cada3ba..750826c 100644
--- a/arch/m32r/kernel/time.c
+++ b/arch/m32r/kernel/time.c
@@ -158,7 +158,7 @@ int do_settimeofday(struct timespec *tv)
ntp_clear();
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c
index 54d9807..1d9dc12 100644
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -155,7 +155,7 @@ int do_settimeofday(struct timespec *tv)
ntp_clear();
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
diff --git a/arch/sparc/kernel/time_32.c b/arch/sparc/kernel/time_32.c
index 614ac7b..b987855 100644
--- a/arch/sparc/kernel/time_32.c
+++ b/arch/sparc/kernel/time_32.c
@@ -284,7 +284,7 @@ int do_settimeofday(struct timespec *tv)
write_seqlock_irq(&xtime_lock);
ret = bus_do_settimeofday(tv);
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return ret;
}
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 0b56fd4..162a0a0 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -13,6 +13,7 @@
#include <linux/clockchips.h>
#include <linux/kernel_stat.h>
#include <linux/math64.h>
+#include <linux/notifier.h>
#include <asm/pvclock.h>
#include <asm/xen/hypervisor.h>
@@ -526,6 +527,42 @@ static int __init xen_setup_vsyscall_timeinfo(int cpu)
}
#endif /* CONFIG_PARAVIRT_CLOCK_VSYSCALL */
+static void sync_xen_wallclock(unsigned long dummy);
+static DEFINE_TIMER(sync_xen_wallclock_timer, sync_xen_wallclock, 0, 0);
+static void sync_xen_wallclock(unsigned long dummy)
+{
+ struct xen_platform_op op;
+ struct timespec ts;
+
+ write_seqlock_irq(&xtime_lock);
+
+ set_normalized_timespec(&ts, xtime.tv_sec, xtime.tv_nsec);
+
+ op.cmd = XENPF_settime;
+ op.u.settime.secs = ts.tv_sec;
+ op.u.settime.nsecs = ts.tv_nsec;
+ op.u.settime.system_time = xen_clocksource_read();
+ WARN_ON(HYPERVISOR_dom0_op(&op));
+
+ write_sequnlock_irq(&xtime_lock);
+
+ /* Once per minute. */
+ mod_timer(&sync_xen_wallclock_timer, jiffies + 60*HZ);
+}
+
+int xen_update_persistent_clock(struct notifier_block *this,
+ unsigned long event, void *ptr)
+{
+ if (!xen_initial_domain())
+ return -1;
+ mod_timer(&sync_xen_wallclock_timer, jiffies + 1);
+ return 0;
+}
+
+static struct notifier_block xen_clock_was_set = {
+ .notifier_call = xen_update_persistent_clock,
+};
+
__init void xen_time_init(void)
{
int cpu = smp_processor_id();
@@ -549,6 +586,8 @@ __init void 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(&clockset_notifier_list,
&xen_clock_was_set);
#ifdef CONFIG_PARAVIRT_CLOCK_VSYSCALL
if (xen_setup_vsyscall_timeinfo(cpu) == 0)
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 5d42d55..422e8ef 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -130,7 +130,7 @@ out_resume:
dpm_resume_end(PMSG_RESUME);
/* Make sure timer events get retriggered on all CPUs */
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
out_thaw:
#ifdef CONFIG_PREEMPT
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 4759917..c46a4e5 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -247,7 +247,6 @@ static inline ktime_t hrtimer_expires_remaining(const struct
hrtimer *timer)
#ifdef CONFIG_HIGH_RES_TIMERS
struct clock_event_device;
-extern void clock_was_set(void);
extern void hres_timers_resume(void);
extern void hrtimer_interrupt(struct clock_event_device *dev);
@@ -282,12 +281,6 @@ extern void hrtimer_peek_ahead_timers(void);
# define MONOTONIC_RES_NSEC LOW_RES_NSEC
# define KTIME_MONOTONIC_RES KTIME_LOW_RES
-/*
- * clock_was_set() is a NOP for non- high-resolution systems. The
- * time-sorted order guarantees that a timer does not expire early and
- * is expired in the next softirq when the clock was advanced.
- */
-static inline void clock_was_set(void) { }
static inline void hrtimer_peek_ahead_timers(void) { }
static inline void hres_timers_resume(void) { }
diff --git a/include/linux/time.h b/include/linux/time.h
index ea16c1a..26367c2 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -7,6 +7,7 @@
# include <linux/cache.h>
# include <linux/seqlock.h>
# include <linux/math64.h>
+# include <linux/notifier.h>
#endif
#ifndef _STRUCT_TIMESPEC
@@ -131,6 +132,7 @@ static inline u32 arch_gettimeoffset(void) { return 0; }
extern void do_gettimeofday(struct timeval *tv);
extern int do_settimeofday(struct timespec *tv);
extern int do_sys_settimeofday(struct timespec *tv, struct timezone *tz);
+extern struct atomic_notifier_head clockset_notifier_list;
#define do_posix_clock_monotonic_gettime(ts) ktime_get_ts(ts)
extern long do_utimes(int dfd, char __user *filename, struct timespec *times,
int flags);
struct itimerval;
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 49da79a..18edb2e 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -665,12 +665,17 @@ static void retrigger_next_event(void *arg)
* resolution timer interrupts. On UP we just disable interrupts and
* call the high resolution interrupt code.
*/
-void clock_was_set(void)
+static int clock_was_set(struct notifier_block *this, unsigned long event,
+ void *ptr)
{
/* Retrigger the CPU local events everywhere */
on_each_cpu(retrigger_next_event, NULL, 1);
}
+static struct notifier_block hrt_clock_was_set = {
+ .notifier_call = clock_was_set,
+};
+
/*
* During resume we might have to reprogram the high resolution timer
* interrupt (on the local CPU):
@@ -1726,6 +1731,7 @@ void __init hrtimers_init(void)
(void *)(long)smp_processor_id());
register_cpu_notifier(&hrtimers_nb);
#ifdef CONFIG_HIGH_RES_TIMERS
+ atomic_notifier_chain_register(&clockset_notifier_list,
&hrt_clock_was_set);
open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
#endif
}
diff --git a/kernel/time.c b/kernel/time.c
index 2951194..667b959 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -138,7 +138,7 @@ static inline void warp_clock(void)
xtime.tv_sec += sys_tz.tz_minuteswest * 60;
update_xtime_cache(0);
write_sequnlock_irq(&xtime_lock);
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
}
/*
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e8c77d9..284539f 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -18,7 +18,11 @@
#include <linux/jiffies.h>
#include <linux/time.h>
#include <linux/tick.h>
+#include <linux/notifier.h>
+ATOMIC_NOTIFIER_HEAD(clockset_notifier_list);
+
+EXPORT_SYMBOL(clockset_notifier_list);
/*
* This read-write spinlock protects us from races in SMP while
@@ -174,8 +178,7 @@ int do_settimeofday(struct timespec *tv)
write_sequnlock_irqrestore(&xtime_lock, flags);
- /* signal hrtimers about time change */
- clock_was_set();
+ atomic_notifier_call_chain(&clockset_notifier_list, 0, NULL);
return 0;
}
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