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x86/tsc: Add a timer to make sure TSC_adjust is always checked

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commit c7719e79347803b8e3b6b50da8c6db410a3012b5 upstream.

The TSC_ADJUST register is checked every time a CPU enters idle state, but
Thomas Gleixner mentioned there is still a caveat that a system won't enter
idle [1], either because it's too busy or configured purposely to not enter
idle.

Setup a periodic timer (every 10 minutes) to make sure the check is
happening on a regular base.

[1] https://lore.kernel.org/lkml/875z286xtk.fsf@nanos.tec.linutronix.de/

Fixes: 6e3cd95234dc ("x86/hpet: Use another crystalball to evaluate HPET usability")
Requested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211117023751.24190-1-feng.tang@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Feng Tang 2021-11-17 10:37:50 +08:00 committed by Greg Kroah-Hartman
parent 957a203fe1
commit fe3cd48420
1 changed files with 41 additions and 0 deletions
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41
arch/x86/kernel/tsc_sync.c
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@ -30,6 +30,7 @@ struct tsc_adjust {
};
static DEFINE_PER_CPU(struct tsc_adjust, tsc_adjust);
static struct timer_list tsc_sync_check_timer;
/*
* TSC's on different sockets may be reset asynchronously.
@ -77,6 +78,46 @@ void tsc_verify_tsc_adjust(bool resume)
}
}
/*
* Normally the tsc_sync will be checked every time system enters idle
* state, but there is still caveat that a system won't enter idle,
* either because it's too busy or configured purposely to not enter
* idle.
*
* So setup a periodic timer (every 10 minutes) to make sure the check
* is always on.
*/
#define SYNC_CHECK_INTERVAL (HZ * 600)
static void tsc_sync_check_timer_fn(struct timer_list *unused)
{
int next_cpu;
tsc_verify_tsc_adjust(false);
/* Run the check for all onlined CPUs in turn */
next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
if (next_cpu >= nr_cpu_ids)
next_cpu = cpumask_first(cpu_online_mask);
tsc_sync_check_timer.expires += SYNC_CHECK_INTERVAL;
add_timer_on(&tsc_sync_check_timer, next_cpu);
}
static int __init start_sync_check_timer(void)
{
if (!cpu_feature_enabled(X86_FEATURE_TSC_ADJUST) || tsc_clocksource_reliable)
return 0;
timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn, 0);
tsc_sync_check_timer.expires = jiffies + SYNC_CHECK_INTERVAL;
add_timer(&tsc_sync_check_timer);
return 0;
}
late_initcall(start_sync_check_timer);
static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval,
unsigned int cpu, bool bootcpu)
{