From patchwork Mon Jun 15 17:36:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chen Yu X-Patchwork-Id: 11605459 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A40B990 for ; Mon, 15 Jun 2020 17:35:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 933332078E for ; Mon, 15 Jun 2020 17:35:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730961AbgFORfT (ORCPT ); Mon, 15 Jun 2020 13:35:19 -0400 Received: from mga07.intel.com ([134.134.136.100]:60144 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729847AbgFORfS (ORCPT ); Mon, 15 Jun 2020 13:35:18 -0400 IronPort-SDR: YwrT5Lkv5HZDZsACtBnspln9ds2k3+nKIKngwPmAg5bR7NfA9dw6hD+YURDvD7KXcbNhvWd2zj GMR7msC99AmQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2020 10:35:18 -0700 IronPort-SDR: 51+mZbATzb7maRcHc1mjVbVrxDqDO6M2cv45SsM7b+oxHngCDcFSqacinDVTDXr7OPEcmXRB/a d40MxvSKq9pQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,515,1583222400"; d="scan'208";a="298594064" Received: from chenyu-office.sh.intel.com ([10.239.158.173]) by fmsmga004.fm.intel.com with ESMTP; 15 Jun 2020 10:35:16 -0700 From: Chen Yu To: "Rafael J. Wysocki" , Peter Zijlstra Cc: Daniel Lezcano , Ingo Molnar , Len Brown , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Yu Subject: [PATCH][RFC] PM / s2idle: Clear _TIF_POLLING_NRFLAG before suspend to idle Date: Tue, 16 Jun 2020 01:36:11 +0800 Message-Id: <20200615173611.15349-1-yu.c.chen@intel.com> X-Mailer: git-send-email 2.17.1 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Suspend to idle was found to not work on Goldmont CPU recently. And the issue was triggered due to: 1. On Goldmont the CPU in idle can only be woken up via IPIs, not POLL mode: 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 is kept on. 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. I don't find a way in Ubuntu to update the firmware of Goldmont and check if the issue was gone, a fix patch would do no harm. Clear the _TIF_POLLING_NRFLAG flag before entering suspend to idle, and let the driver's enter_s2idle() to decide whether to set _TIF_POLLING_NRFLAG or not. So that to avoid the scenario described above and keep the context consistent with before. Fixes: b2a02fc43a1f ("smp: Optimize send_call_function_single_ipi()") Reported-by: kbuild test robot Cc: Peter Zijlstra (Intel) Signed-off-by: Chen Yu --- drivers/cpuidle/cpuidle.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index c149d9e20dfd..d17dad362d34 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -186,8 +187,10 @@ 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(); enter_s2idle_proper(drv, dev, index); + } return index; }