linux-kernel - [PATCH v4 02/10] timekeeper: introduce boot field in system_time

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Date:   Wed,  2 Aug 2017 17:38:02 +0300
From:   Denis Plotnikov <dplotnikov@...tuozzo.com>
To:     pbonzini@...hat.com, rkrcmar@...hat.com, kvm@...r.kernel.org,
        john.stultz@...aro.org, tglx@...utronix.de
Cc:     mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
        x86@...nel.org, rkagan@...tuozzo.com, den@...tuozzo.com
Subject: [PATCH v4 02/10] timekeeper: introduce boot field in system_time_snapshot

The field keeps monotonic time since boot.

The value of boot will be used in KVM for masterclock.

This is a part of the work aiming to move to a more simple scheme
of masterclock related values calculation in KVM

Signed-off-by: Denis Plotnikov <dplotnikov@...tuozzo.com>
---
 include/linux/timekeeping.h | 2 ++
 kernel/time/timekeeping.c   | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index ddc229f..5008e3e 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -283,6 +283,7 @@ extern void ktime_get_raw_and_real_ts64(struct timespec64 *ts_raw,
  * @cycles:	Clocksource counter value to produce the system times
  * @real:	Realtime system time
  * @raw:	Monotonic raw system time
+ * @boot:	Monotonic time since boot
  * @clock_was_set_seq:	The sequence number of clock was set events
  * @cs_was_changed_seq:	The sequence number of clocksource change events
  */
@@ -290,6 +291,7 @@ struct system_time_snapshot {
 	u64		cycles;
 	ktime_t		real;
 	ktime_t		raw;
+	ktime_t		boot;
 	unsigned int	clock_was_set_seq;
 	u8		cs_was_changed_seq;
 };
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index cedafa0..66f7701 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -953,6 +953,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 	unsigned long seq;
 	ktime_t base_raw;
 	ktime_t base_real;
+	ktime_t base_boot;
 	u64 nsec_raw;
 	u64 nsec_real;
 	u64 now;
@@ -967,6 +968,8 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 		base_real = ktime_add(tk->tkr_mono.base,
 				      tk_core.timekeeper.offs_real);
 		base_raw = tk->tkr_raw.base;
+		base_boot = ktime_add(tk->tkr_mono.base,
+					tk_core.timekeeper.offs_boot);
 		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 		nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
 	} while (read_seqcount_retry(&tk_core.seq, seq));
@@ -974,6 +977,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 	systime_snapshot->cycles = now;
 	systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
 	systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
+	systime_snapshot->boot = ktime_add_ns(base_boot, nsec_real);
 }
 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 
-- 
2.7.4