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.
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Index: vsyscall/include/linux/pvclock_gtod.h
===================================================================
--- /dev/null
+++ vsyscall/include/linux/pvclock_gtod.h
@@ -0,0 +1,27 @@
+#ifndef _PVCLOCK_GTOD_H
+#define _PVCLOCK_GTOD_H
+
+#include <linux/clocksource.h>
+#include <linux/notifier.h>
+
+struct pvclock_gtod_data {
+ seqcount_t seq;
+
+ struct { /* extract of a clocksource struct */
+ int vclock_mode;
+ cycle_t cycle_last;
+ cycle_t mask;
+ u32 mult;
+ u32 shift;
+ } clock;
+
+ /* open coded 'struct timespec' */
+ u64 monotonic_time_snsec;
+ time_t monotonic_time_sec;
+};
+extern struct pvclock_gtod_data pvclock_gtod_data;
+
+extern int pvclock_gtod_register_notifier(struct notifier_block *nb);
+extern int pvclock_gtod_unregister_notifier(struct notifier_block *nb);
+
+#endif /* _PVCLOCK_GTOD_H */
Index: vsyscall/kernel/time/timekeeping.c
===================================================================
--- vsyscall.orig/kernel/time/timekeeping.c
+++ vsyscall/kernel/time/timekeeping.c
@@ -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 +181,79 @@ static inline s64 timekeeping_get_ns_raw
return nsec + arch_gettimeoffset();
}
+static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
+
+/**
+ * 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);
+ 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);
+
+struct pvclock_gtod_data pvclock_gtod_data;
+EXPORT_SYMBOL_GPL(pvclock_gtod_data);
+
+static void update_pvclock_gtod(struct timekeeper *tk)
+{
+ struct pvclock_gtod_data *vdata = &pvclock_gtod_data;
+
+ write_seqcount_begin(&vdata->seq);
+
+ /* copy pvclock gtod data */
+ vdata->clock.vclock_mode = tk->clock->archdata.vclock_mode;
+ vdata->clock.cycle_last = tk->clock->cycle_last;
+ vdata->clock.mask = tk->clock->mask;
+ vdata->clock.mult = tk->mult;
+ vdata->clock.shift = tk->shift;
+
+ vdata->monotonic_time_sec = tk->xtime_sec
+ + tk->wall_to_monotonic.tv_sec;
+ vdata->monotonic_time_snsec = tk->xtime_nsec
+ + (tk->wall_to_monotonic.tv_nsec
+ << tk->shift);
+ while (vdata->monotonic_time_snsec >=
+ (((u64)NSEC_PER_SEC) << tk->shift)) {
+ vdata->monotonic_time_snsec -=
+ ((u64)NSEC_PER_SEC) << tk->shift;
+ vdata->monotonic_time_sec++;
+ }
+
+ write_seqcount_end(&vdata->seq);
+ raw_notifier_call_chain(&pvclock_gtod_chain, 0, NULL);
+}
+
/* must hold write on timekeeper.lock */
static void timekeeping_update(struct timekeeper *tk, bool clearntp)
{
@@ -188,6 +262,7 @@ static void timekeeping_update(struct ti
ntp_clear();
}
update_vsyscall(tk);
+ update_pvclock_gtod(tk);
}
/**
--
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