For tracing purpose, the boot clock is interesting as it doesn't stop on
suspend. Export it as part of the time snapshot. This will later allow
the hypervisor to add boot clock timestamps to its events.

Cc: John Stultz <jstultz@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Christopher S. Hall <christopher.s.hall@intel.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index fc12a9ba2c88..e85c27347e44 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -275,6 +275,7 @@ struct ktime_timestamps {
  *				 counter value
  * @cycles:	Clocksource counter value to produce the system times
  * @real:	Realtime system time
+ * @boot:	Boot time
  * @raw:	Monotonic raw system time
  * @cs_id:	Clocksource ID
  * @clock_was_set_seq:	The sequence number of clock-was-set events
@@ -283,6 +284,7 @@ struct ktime_timestamps {
 struct system_time_snapshot {
 	u64			cycles;
 	ktime_t			real;
+	ktime_t			boot;
 	ktime_t			raw;
 	enum clocksource_ids	cs_id;
 	unsigned int		clock_was_set_seq;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5391e4167d60..db16c44dccc3 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1060,6 +1060,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 	unsigned int seq;
 	ktime_t base_raw;
 	ktime_t base_real;
+	ktime_t base_boot;
 	u64 nsec_raw;
 	u64 nsec_real;
 	u64 now;
@@ -1074,6 +1075,8 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 		systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
 		base_real = ktime_add(tk->tkr_mono.base,
 				      tk_core.timekeeper.offs_real);
+		base_boot = ktime_add(tk->tkr_mono.base,
+				      tk_core.timekeeper.offs_boot);
 		base_raw = tk->tkr_raw.base;
 		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 		nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
@@ -1081,6 +1084,7 @@ 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->boot = ktime_add_ns(base_boot, nsec_real);
 	systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
 }
 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
-- 
2.46.0.598.g6f2099f65c-goog

On Wed, Sep 11 2024 at 10:30, Vincent Donnefort wrote:
> For tracing purpose, the boot clock is interesting as it doesn't stop on
> suspend. Export it as part of the time snapshot. This will later allow
> the hypervisor to add boot clock timestamps to its events.
>
> Cc: John Stultz <jstultz@google.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: Christopher S. Hall <christopher.s.hall@intel.com>
> Cc: Richard Cochran <richardcochran@gmail.com>
> Cc: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

I've queued this in on top of v6.12-rc1 as I have upcoming time keeping
changes. I've tagged this commit so it can be pulled by the arm64/kvm
people to base the other changes on:

 git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git tk-for-arm64-kvm

Thanks,

        tglx

On Wed, Sep 11, 2024 at 2:30 AM Vincent Donnefort <vdonnefort@google.com> wrote:
>
> For tracing purpose, the boot clock is interesting as it doesn't stop on
> suspend. Export it as part of the time snapshot. This will later allow
> the hypervisor to add boot clock timestamps to its events.
>
> Cc: John Stultz <jstultz@google.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: Christopher S. Hall <christopher.s.hall@intel.com>
> Cc: Richard Cochran <richardcochran@gmail.com>
> Cc: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

Acked-by: John Stultz <jstultz@google.com>

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     8102c4daf44ab86c2d2226a8136bec905d6e2bd1
Gitweb:        https://git.kernel.org/tip/8102c4daf44ab86c2d2226a8136bec905d6e2bd1
Author:        Vincent Donnefort <vdonnefort@google.com>
AuthorDate:    Wed, 11 Sep 2024 10:30:20 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 02 Oct 2024 17:10:41 +02:00

timekeeping: Add the boot clock to system time snapshot

For tracing purpose, the boot clock is interesting as it doesn't stop on
suspend. Export it as part of the time snapshot. This will later allow
the hypervisor to add boot clock timestamps to its events.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20240911093029.3279154-5-vdonnefort@google.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 fc12a9b..e85c273 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -275,6 +275,7 @@ struct ktime_timestamps {
  *				 counter value
  * @cycles:	Clocksource counter value to produce the system times
  * @real:	Realtime system time
+ * @boot:	Boot time
  * @raw:	Monotonic raw system time
  * @cs_id:	Clocksource ID
  * @clock_was_set_seq:	The sequence number of clock-was-set events
@@ -283,6 +284,7 @@ struct ktime_timestamps {
 struct system_time_snapshot {
 	u64			cycles;
 	ktime_t			real;
+	ktime_t			boot;
 	ktime_t			raw;
 	enum clocksource_ids	cs_id;
 	unsigned int		clock_was_set_seq;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 7e6f409..47e44b9 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1060,6 +1060,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 	unsigned int seq;
 	ktime_t base_raw;
 	ktime_t base_real;
+	ktime_t base_boot;
 	u64 nsec_raw;
 	u64 nsec_real;
 	u64 now;
@@ -1074,6 +1075,8 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 		systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
 		base_real = ktime_add(tk->tkr_mono.base,
 				      tk_core.timekeeper.offs_real);
+		base_boot = ktime_add(tk->tkr_mono.base,
+				      tk_core.timekeeper.offs_boot);
 		base_raw = tk->tkr_raw.base;
 		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 		nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
@@ -1081,6 +1084,7 @@ 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->boot = ktime_add_ns(base_boot, nsec_real);
 	systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
 }
 EXPORT_SYMBOL_GPL(ktime_get_snapshot);