From e0b306fef90556233797d2e1747bd6a3ae35ea93 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Tue, 27 Nov 2012 23:28:59 -0200 Subject: [PATCH] time: export time information for KVM pvclock As suggested by John, export time data similarly to how its done by vsyscall support. This allows KVM to retrieve necessary information to implement vsyscall support in KVM guests. Acked-by: John Stultz Signed-off-by: Marcelo Tosatti --- include/linux/pvclock_gtod.h | 9 ++++++++ kernel/time/timekeeping.c | 50 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) create mode 100644 include/linux/pvclock_gtod.h diff --git a/include/linux/pvclock_gtod.h b/include/linux/pvclock_gtod.h new file mode 100644 index 0000000..0ca7582 --- /dev/null +++ b/include/linux/pvclock_gtod.h @@ -0,0 +1,9 @@ +#ifndef _PVCLOCK_GTOD_H +#define _PVCLOCK_GTOD_H + +#include + +extern int pvclock_gtod_register_notifier(struct notifier_block *nb); +extern int pvclock_gtod_unregister_notifier(struct notifier_block *nb); + +#endif /* _PVCLOCK_GTOD_H */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index e424970..69f5342 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -21,6 +21,7 @@ #include #include #include +#include static struct timekeeper timekeeper; @@ -180,6 +181,54 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk) return nsec + arch_gettimeoffset(); } +static RAW_NOTIFIER_HEAD(pvclock_gtod_chain); + +static void update_pvclock_gtod(struct timekeeper *tk) +{ + raw_notifier_call_chain(&pvclock_gtod_chain, 0, tk); +} + +/** + * pvclock_gtod_register_notifier - register a pvclock timedata update listener + * + * Must hold write on timekeeper.lock + */ +int pvclock_gtod_register_notifier(struct notifier_block *nb) +{ + struct timekeeper *tk = &timekeeper; + unsigned long flags; + int ret; + + write_seqlock_irqsave(&tk->lock, flags); + ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb); + /* update timekeeping data */ + update_pvclock_gtod(tk); + write_sequnlock_irqrestore(&tk->lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier); + +/** + * pvclock_gtod_unregister_notifier - unregister a pvclock + * timedata update listener + * + * Must hold write on timekeeper.lock + */ +int pvclock_gtod_unregister_notifier(struct notifier_block *nb) +{ + struct timekeeper *tk = &timekeeper; + unsigned long flags; + int ret; + + write_seqlock_irqsave(&tk->lock, flags); + ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb); + write_sequnlock_irqrestore(&tk->lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier); + /* must hold write on timekeeper.lock */ static void timekeeping_update(struct timekeeper *tk, bool clearntp) { @@ -188,6 +237,7 @@ static void timekeeping_update(struct timekeeper *tk, bool clearntp) ntp_clear(); } update_vsyscall(tk); + update_pvclock_gtod(tk); } /** -- 2.7.4