Merge tag 'timers-ptp-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

Pull timekeeping updates from Thomas Gleixner:
 "Updates for NTP/timekeeping and PTP:

   - Expand timekeeping snapshot mechanisms

     The various snapshot functions are mostly used for PTP to collect
     "atomic" snapshots of various involved clocks.

     They lack support for the recently introduced AUX clocks and do not
     provide the underlying counter value (e.g. TSC) to user space.
     Exposing the counter value snapshot allows for better control and
     steering.

     Convert the hard wired ktime_get_snapshot() to take a clock ID,
     which allows the caller to select the clock ID to be captured along
     with CLOCK_MONONOTONIC_RAW. Additionally capture the underlying
     hardware counter value and the clock source ID of the counter.

     Expand the hardware based snapshot capture where devices provide a
     mechanism to snapshot the hardware PTP clock and the system counter
     (usually via PCI/PTM) to support AUX clocks and also provide the
     captured counter value back to the caller and not only the clock
     timestamps derived from it.

   - Add a new optional read_snapshot() callback to clocksources

     That is required to capture atomic snapshots from clocksources
     which are derived from TSC with a scaling mechanism (e.g. Hyper-V,
     KVMclock).

     The value pair is handed back in the snapshot structure to the
     callers, so they can do the necessary correlations in a more
     precise way.

  This touches usage sites of the affected functions and data structure
  all over the tree, but stays fully backwards compatible for the
  existing user space exposed interfaces. New PTP IOCTLs will provide
  access to the extended functionality in later kernel versions"

* tag 'timers-ptp-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (28 commits)
  ptp: vmclock: Use hw_cycles from snapshot for precise TSC pairing
  x86/kvmclock: Implement read_snapshot() for kvmclock clocksource
  clocksource/hyperv: Implement read_snapshot() for TSC page clocksource
  timekeeping: Add clocksource read_snapshot() method and hw_cycles to snapshot
  ptp: Switch to ktime_get_snapshot_id() for pre/post timestamps
  timekeeping: Add support for AUX clock cross timestamping
  timekeeping: Remove system_device_crosststamp::sys_realtime
  ALSA: hda/common: Use system_device_crosststamp::sys_systime
  wifi: iwlwifi: Use system_device_crosststamp::sys_systime
  ptp: Use system_device_crosststamp::sys_systime
  timekeeping: Prepare for cross timestamps on arbitrary clock IDs
  timekeeping: Remove ktime_get_snapshot()
  virtio_rtc: Use provided clock ID for history snapshot
  net/mlx5: Use provided clock ID for history snapshot
  igc: Use provided clock ID for history snapshot
  ice/ptp: Use provided clock ID for history snapshot
  wifi: iwlwifi: Adopt PTP cross timestamps to core changes
  timekeeping: Add CLOCK ID to system_device_crosststamp
  timekeeping: Add system_counterval_t to struct system_device_crosststamp
  timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()
  ...

4 files changed, 74 insertions, 36 deletions

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index b12a6d19aa60..283d7297aa79 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -32,6 +32,21 @@ struct module;
 #include <vdso/clocksource.h>
 
 /**
+ * struct clocksource_hw_snapshot - Snapshot for the underlying hardware counter of derived
+ *				    clocksources like kvmclock or Hyper-V scaled TSC
+ * @hw_cycles:		The hardware counter value
+ * @hw_csid:		Clocksource ID of the hardware counter
+ *
+ * Such clocksources must implement the read_snapshot() callback and fill in the
+ * hardware counter value, the clocksource ID of the hardware counter and derive
+ * the actual clocksource cycles from @hw_cycles to provide an atomic snapshot
+ */
+struct clocksource_hw_snapshot {
+	u64			hw_cycles;
+	enum clocksource_ids	hw_csid;
+};
+
+/**
  * struct clocksource - hardware abstraction for a free running counter
  *	Provides mostly state-free accessors to the underlying hardware.
  *	This is the structure used for system time.
@@ -72,6 +87,14 @@ struct module;
  * @flags:		Flags describing special properties
  * @base:		Hardware abstraction for clock on which a clocksource
  *			is based
+ * @read_snapshot:	Extended @read() function for clocksources such as
+ *			kvmclock or the Hyper-V scaled TSC where the actual
+ *			clocksource value for timekeeping is calculated from an
+ *			underlying hardware counter. Returns the timekeeping
+ *			relevant cycle value and stores the raw value of the
+ *			underlying counter from which it was calculated
+ *			including the clocksource ID of that counter in the
+ *			clocksource hardware snapshot.
  * @enable:		Optional function to enable the clocksource
  * @disable:		Optional function to disable the clocksource
  * @suspend:		Optional suspend function for the clocksource
@@ -113,6 +136,7 @@ struct clocksource {
 	unsigned long		flags;
 	struct clocksource_base *base;
 
+	u64			(*read_snapshot)(struct clocksource *cs, struct clocksource_hw_snapshot *chs);
 	int			(*enable)(struct clocksource *cs);
 	void			(*disable)(struct clocksource *cs);
 	void			(*suspend)(struct clocksource *cs);
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index aab0aebb529e..9f088c9023b1 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -99,12 +99,14 @@ static inline void timespec_to_pps_ktime(struct pps_ktime *kt,
 
 static inline void pps_get_ts(struct pps_event_time *ts)
 {
+#ifdef CONFIG_NTP_PPS
 	struct system_time_snapshot snap;
 
-	ktime_get_snapshot(&snap);
-	ts->ts_real = ktime_to_timespec64(snap.real);
-#ifdef CONFIG_NTP_PPS
-	ts->ts_raw = ktime_to_timespec64(snap.raw);
+	ktime_get_snapshot_id(CLOCK_REALTIME, &snap);
+	ts->ts_real = ktime_to_timespec64(snap.systime);
+	ts->ts_raw = ktime_to_timespec64(snap.monoraw);
+#else
+	ktime_get_real_ts64(&ts->ts_real);
 #endif
 }
 
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 884364596dd3..36a27a910595 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -12,6 +12,7 @@
 #include <linux/pps_kernel.h>
 #include <linux/ptp_clock.h>
 #include <linux/timecounter.h>
+#include <linux/timekeeping.h>
 #include <linux/skbuff.h>
 
 #define PTP_CLOCK_NAME_LEN	32
@@ -45,13 +46,13 @@ struct system_device_crosststamp;
 
 /**
  * struct ptp_system_timestamp - system time corresponding to a PHC timestamp
- * @pre_ts: system timestamp before capturing PHC
- * @post_ts: system timestamp after capturing PHC
- * @clockid: clock-base used for capturing the system timestamps
+ * @pre_sts:	system time snapshot before capturing PHC
+ * @post_sts:	system time snapshot after capturing PHC
+ * @clockid:	clock-base used for capturing the system timestamps
  */
 struct ptp_system_timestamp {
-	struct timespec64 pre_ts;
-	struct timespec64 post_ts;
+	struct system_time_snapshot pre_sts;
+	struct system_time_snapshot post_sts;
 	clockid_t clockid;
 };
 
@@ -510,13 +511,13 @@ static inline ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp,
 static inline void ptp_read_system_prets(struct ptp_system_timestamp *sts)
 {
 	if (sts)
-		ktime_get_clock_ts64(sts->clockid, &sts->pre_ts);
+		ktime_get_snapshot_id(sts->clockid, &sts->pre_sts);
 }
 
 static inline void ptp_read_system_postts(struct ptp_system_timestamp *sts)
 {
 	if (sts)
-		ktime_get_clock_ts64(sts->clockid, &sts->post_ts);
+		ktime_get_snapshot_id(sts->clockid, &sts->post_sts);
 }
 
 #endif
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index aee2c1a46e47..984a866d293b 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -276,37 +276,30 @@ static inline bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt) { ret
 #endif
 
 /**
- * struct system_time_snapshot - simultaneous raw/real time capture with
- *				 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
+ * struct system_time_snapshot - Simultaneous time capture of CLOCK_MONOTONIC_RAW,
+ *				 a selected CLOCK_* and the clocksource counter value
+ * @cycles:		Clocksource counter value to produce the system times
+ * @hw_cycles:		For derived clocksources, the hardware counter value from
+ *			which @cycles was derived
+ * @systime:		The system time of the selected CLOCK ID
+ * @monoraw:		Monotonic raw system time
+ * @cs_id:		Clocksource ID
+ * @hw_csid:		Clocksource ID of the underlying hardware counter for derived
+ *			clocksources which implement the read_snapshot() callback.
  * @clock_was_set_seq:	The sequence number of clock-was-set events
  * @cs_was_changed_seq:	The sequence number of clocksource change events
+ * @valid:		True if the snapshot is valid
  */
 struct system_time_snapshot {
 	u64			cycles;
-	ktime_t			real;
-	ktime_t			boot;
-	ktime_t			raw;
+	u64			hw_cycles;
+	ktime_t			systime;
+	ktime_t			monoraw;
 	enum clocksource_ids	cs_id;
+	enum clocksource_ids	hw_csid;
 	unsigned int		clock_was_set_seq;
 	u8			cs_was_changed_seq;
-};
-
-/**
- * struct system_device_crosststamp - system/device cross-timestamp
- *				      (synchronized capture)
- * @device:		Device time
- * @sys_realtime:	Realtime simultaneous with device time
- * @sys_monoraw:	Monotonic raw simultaneous with device time
- */
-struct system_device_crosststamp {
-	ktime_t device;
-	ktime_t sys_realtime;
-	ktime_t sys_monoraw;
+	u8			valid;
 };
 
 /**
@@ -325,6 +318,23 @@ struct system_counterval_t {
 	bool			use_nsecs;
 };
 
+/**
+ * struct system_device_crosststamp - system/device cross-timestamp
+ *				      (synchronized capture)
+ * @clock_id:		System time Clock ID to capture
+ * @device:		Device time
+ * @sys_counter:	Clocksource counter value simultaneous with device time
+ * @sys_systime:	System time for @clock_id
+ * @sys_monoraw:	Monotonic raw simultaneous with device time
+ */
+struct system_device_crosststamp {
+	clockid_t			clock_id;
+	ktime_t				device;
+	struct system_counterval_t	sys_counter;
+	ktime_t				sys_systime;
+	ktime_t				sys_monoraw;
+};
+
 extern bool ktime_real_to_base_clock(ktime_t treal,
 				     enum clocksource_ids base_id, u64 *cycles);
 extern bool timekeeping_clocksource_has_base(enum clocksource_ids id);
@@ -341,9 +351,10 @@ extern int get_device_system_crosststamp(
 			struct system_device_crosststamp *xtstamp);
 
 /*
- * Simultaneously snapshot realtime and monotonic raw clocks
+ * Simultaneously snapshot a given clock with MONOTONIC_RAW and the underlying
+ * clocksource counter value.
  */
-extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
+extern void ktime_get_snapshot_id(clockid_t clock_id, struct system_time_snapshot *systime_snapshot);
 
 /*
  * Persistent clock related interfaces