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time: export time information for KVM pvclock

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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 <johnstul@us.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti 2012-11-27 23:28:59 -02:00
parent 886b470cb1
commit e0b306fef9
2 changed files with 59 additions and 0 deletions
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9
include/linux/pvclock_gtod.h Normal file
View file

@ -0,0 +1,9 @@
#ifndef _PVCLOCK_GTOD_H
#define _PVCLOCK_GTOD_H
#include <linux/notifier.h>
extern int pvclock_gtod_register_notifier(struct notifier_block *nb);
extern int pvclock_gtod_unregister_notifier(struct notifier_block *nb);
#endif /* _PVCLOCK_GTOD_H */

50
kernel/time/timekeeping.c
View file

@ -21,6 +21,7 @@
#include <linux/time.h>
#include <linux/tick.h>
#include <linux/stop_machine.h>
#include <linux/pvclock_gtod.h>
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);
}
/**