From: Thomas Gleixner <[email protected]> In some scenario like return device time to ptp_kvm guest, we need identify the current clocksource outside core time code. This patch add a mechanism to recognize the current clocksource by export clocksource id in time_get_snapshot.
Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Jianyong Wu <[email protected]> --- include/linux/clocksource.h | 6 ++++++ include/linux/timekeeping.h | 12 +++++++----- kernel/time/clocksource.c | 3 +++ kernel/time/timekeeping.c | 1 + 4 files changed, 17 insertions(+), 5 deletions(-) diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index b21db536fd52..ac8016b22734 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -19,6 +19,7 @@ #include <linux/of.h> #include <asm/div64.h> #include <asm/io.h> +#include <linux/clocksource_ids.h> struct clocksource; struct module; @@ -49,6 +50,10 @@ struct module; * 400-499: Perfect * The ideal clocksource. A must-use where * available. + * @id: Defaults to CSID_GENERIC. The id value is captured + * in certain snapshot functions to allow callers to + * validate the clocksource from which the snapshot was + * taken. * @read: returns a cycle value, passes clocksource as argument * @enable: optional function to enable the clocksource * @disable: optional function to disable the clocksource @@ -91,6 +96,7 @@ struct clocksource { const char *name; struct list_head list; int rating; + enum clocksource_ids id; int (*enable)(struct clocksource *cs); void (*disable)(struct clocksource *cs); unsigned long flags; diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index a8ab0f143ac4..ecce56269a7e 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -2,6 +2,7 @@ #ifndef _LINUX_TIMEKEEPING_H #define _LINUX_TIMEKEEPING_H +#include <linux/clocksource_ids.h> #include <linux/errno.h> /* Included from linux/ktime.h */ @@ -204,11 +205,12 @@ extern void timekeeping_inject_sleeptime64(const struct timespec64 *delta); * @cs_was_changed_seq: The sequence number of clocksource change events */ struct system_time_snapshot { - u64 cycles; - ktime_t real; - ktime_t raw; - unsigned int clock_was_set_seq; - u8 cs_was_changed_seq; + u64 cycles; + ktime_t real; + ktime_t raw; + enum clocksource_ids cs_id; + unsigned int clock_was_set_seq; + u8 cs_was_changed_seq; }; /* diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 3bcc19ceb073..26a3add61771 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -921,6 +921,9 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) clocksource_arch_init(cs); + if (WARN_ON_ONCE((unsigned int)cs->id >= CSID_MAX)) + cs->id = CSID_GENERIC; + /* Initialize mult/shift and max_idle_ns */ __clocksource_update_freq_scale(cs, scale, freq); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 44b726bab4bd..88078cff7fe2 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -974,6 +974,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot) do { seq = read_seqcount_begin(&tk_core.seq); now = tk_clock_read(&tk->tkr_mono); + systime_snapshot->cs_id = tk->tkr_mono.clock->id; systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq; systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq; base_real = ktime_add(tk->tkr_mono.base, -- 2.17.1 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
