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x86/tsc: Add a timer to make sure TSC_adjust is always checked
commitc7719e7934
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:6e3cd95234
("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>
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1 changed files with 41 additions and 0 deletions
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@ -30,6 +30,7 @@ struct tsc_adjust {
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};
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static DEFINE_PER_CPU(struct tsc_adjust, tsc_adjust);
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static struct timer_list tsc_sync_check_timer;
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/*
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* TSC's on different sockets may be reset asynchronously.
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@ -77,6 +78,46 @@ void tsc_verify_tsc_adjust(bool resume)
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}
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}
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/*
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* Normally the tsc_sync will be checked every time system enters idle
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* state, but there is still caveat that a system won't enter idle,
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* either because it's too busy or configured purposely to not enter
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* idle.
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*
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* So setup a periodic timer (every 10 minutes) to make sure the check
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* is always on.
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*/
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#define SYNC_CHECK_INTERVAL (HZ * 600)
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static void tsc_sync_check_timer_fn(struct timer_list *unused)
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{
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int next_cpu;
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tsc_verify_tsc_adjust(false);
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/* Run the check for all onlined CPUs in turn */
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next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
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if (next_cpu >= nr_cpu_ids)
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next_cpu = cpumask_first(cpu_online_mask);
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tsc_sync_check_timer.expires += SYNC_CHECK_INTERVAL;
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add_timer_on(&tsc_sync_check_timer, next_cpu);
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}
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static int __init start_sync_check_timer(void)
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{
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if (!cpu_feature_enabled(X86_FEATURE_TSC_ADJUST) || tsc_clocksource_reliable)
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return 0;
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timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn, 0);
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tsc_sync_check_timer.expires = jiffies + SYNC_CHECK_INTERVAL;
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add_timer(&tsc_sync_check_timer);
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return 0;
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}
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late_initcall(start_sync_check_timer);
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static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval,
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unsigned int cpu, bool bootcpu)
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{
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