From 81e6737518a1e392ead4e568a4ee70bb7c371458 Mon Sep 17 00:00:00 2001 From: Chen Yu Date: Tue, 23 Jun 2020 14:31:31 +0800 Subject: PM: s2idle: Clear _TIF_POLLING_NRFLAG before suspend to idle Suspend to idle was found to not work on Goldmont CPU recently. The issue happens due to: 1. On Goldmont the CPU in idle can only be woken up via IPIs, not POLLING mode, due to commit 08e237fa56a1 ("x86/cpu: Add workaround for MONITOR instruction erratum on Goldmont based CPUs") 2. When the CPU is entering suspend to idle process, the _TIF_POLLING_NRFLAG remains on, because cpuidle_enter_s2idle() doesn't match call_cpuidle() exactly. 3. Commit b2a02fc43a1f ("smp: Optimize send_call_function_single_ipi()") makes use of _TIF_POLLING_NRFLAG to avoid sending IPIs to idle CPUs. 4. As a result, some IPIs related functions might not work well during suspend to idle on Goldmont. For example, one suspected victim: tick_unfreeze() -> timekeeping_resume() -> hrtimers_resume() -> clock_was_set() -> on_each_cpu() might wait forever, because the IPIs will not be sent to the CPUs which are sleeping with _TIF_POLLING_NRFLAG set, and Goldmont CPU could not be woken up by only setting _TIF_NEED_RESCHED on the monitor address. To avoid that, clear the _TIF_POLLING_NRFLAG flag before invoking enter_s2idle_proper() in cpuidle_enter_s2idle() in analogy with the call_cpuidle() code flow. Fixes: b2a02fc43a1f ("smp: Optimize send_call_function_single_ipi()") Suggested-by: Peter Zijlstra (Intel) Suggested-by: Rafael J. Wysocki Reported-by: kbuild test robot Signed-off-by: Chen Yu [ rjw: Subject / changelog ] Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/cpuidle.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/cpuidle/cpuidle.c') diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index c149d9e20dfd..e092789187c6 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -186,7 +187,7 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) * be frozen safely. */ index = find_deepest_state(drv, dev, U64_MAX, 0, true); - if (index > 0) + if (index > 0 && !current_clr_polling_and_test()) enter_s2idle_proper(drv, dev, index); return index; -- cgit v1.2.3