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authorMarcelo Tosatti <mtosatti@redhat.com>2012-11-27 23:28:59 -0200
committerMarcelo Tosatti <mtosatti@redhat.com>2012-11-27 23:29:12 -0200
commite0b306fef90556233797d2e1747bd6a3ae35ea93 (patch)
tree0340c76e923fc02a47e5be8bd88c1d75ee0a84f1
parent886b470cb14733a0286e365c77f1844c240c33a4 (diff)
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 <johnstul@us.ibm.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
-rw-r--r--include/linux/pvclock_gtod.h9
-rw-r--r--kernel/time/timekeeping.c50
2 files changed, 59 insertions, 0 deletions
diff --git a/include/linux/pvclock_gtod.h b/include/linux/pvclock_gtod.h
new file mode 100644
index 000000000000..0ca75825b60d
--- /dev/null
+++ b/include/linux/pvclock_gtod.h
@@ -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 */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e424970bb562..69f5342e8d1c 100644
--- a/kernel/time/timekeeping.c
+++ b/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 +181,54 @@ 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);
}
/**