From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B1CF9C433F5 for ; Fri, 6 May 2022 00:14:43 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KvWKG2trMz3dt6 for ; Fri, 6 May 2022 10:14:42 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=e+iTJ8e/; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=192.55.52.115; helo=mga14.intel.com; envelope-from=ricardo.neri-calderon@linux.intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=e+iTJ8e/; dkim-atps=neutral Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KvVzW1PrCz3c8Z for ; Fri, 6 May 2022 09:59:19 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651795159; x=1683331159; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=kUyeigYz7qVM6Mrp46t6dkjR9tV464c8drNXHNVDlvU=; b=e+iTJ8e/bz5WyyyK7usXCVncEM0VR8ZwG6WOXKF6khweNkjRpugd1zPm u/kUCcAwHCUjV7wDgRpQ0HEPqvTE2kV2kDmjKRLtc7FDa9DXHkvjGRpRm ytxw8zhY3yAcUlbzcGTpnpgPFLn5n9Ln7wERoDxID4/DroNT8WnXVUXhy CNa7fasXAxBu+HrWD7l1eWuFP/RUghm+v3TD2JyLuS3SpYmPBQXdpJ49O ew5P+8neks+yEjGflzz41vBtkXD83DR1kpb5dxmXdwNDeGRLMzqpBesgi IRH+cjhUPtxRM+gqMnaiku6hrEj1tKmS8Uu9w38UQmubAzI4eJdG1aFhs Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10338"; a="268437338" X-IronPort-AV: E=Sophos;i="5.91,203,1647327600"; d="scan'208";a="268437338" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 May 2022 16:57:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,203,1647327600"; d="scan'208";a="694914442" Received: from ranerica-svr.sc.intel.com ([172.25.110.23]) by orsmga004.jf.intel.com with ESMTP; 05 May 2022 16:57:55 -0700 From: Ricardo Neri To: Thomas Gleixner , x86@kernel.org Subject: [PATCH v6 25/29] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Date: Thu, 5 May 2022 17:00:04 -0700 Message-Id: <20220506000008.30892-26-ricardo.neri-calderon@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220506000008.30892-1-ricardo.neri-calderon@linux.intel.com> References: <20220506000008.30892-1-ricardo.neri-calderon@linux.intel.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Ravi V. Shankar" , Andi Kleen , linuxppc-dev@lists.ozlabs.org, Joerg Roedel , Ricardo Neri , Stephane Eranian , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Tony Luck , Nicholas Piggin , Suravee Suthikulpanit , Ricardo Neri , Andrew Morton , David Woodhouse , Lu Baolu Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Keep the HPET-based hardlockup detector disabled unless explicitly enabled via a command-line argument. If such parameter is not given, the initialization of the HPET-based hardlockup detector fails and the NMI watchdog will fall back to use the perf-based implementation. Implement the command-line parsing using an early_param, as __setup("nmi_watchdog=") only parses generic options. Cc: Andi Kleen Cc: Stephane Eranian Cc: "Ravi V. Shankar" Cc: iommu@lists.linux-foundation.org Cc: linuxppc-dev@lists.ozlabs.org Cc: x86@kernel.org Reviewed-by: Tony Luck Signed-off-by: Ricardo Neri -- Changes since v5: * None Changes since v4: * None Changes since v3: * None Changes since v2: * Do not imply that using nmi_watchdog=hpet means the detector is enabled. Instead, print a warning in such case. Changes since v1: * Added documentation to the function handing the nmi_watchdog kernel command-line argument. --- .../admin-guide/kernel-parameters.txt | 8 ++++++- arch/x86/kernel/watchdog_hld_hpet.c | 22 +++++++++++++++++++ 2 files changed, 29 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 269be339d738..89eae950fdb8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3370,7 +3370,7 @@ Format: [state][,regs][,debounce][,die] nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels - Format: [panic,][nopanic,][num] + Format: [panic,][nopanic,][num,][hpet] Valid num: 0 or 1 0 - turn hardlockup detector in nmi_watchdog off 1 - turn hardlockup detector in nmi_watchdog on @@ -3381,6 +3381,12 @@ please see 'nowatchdog'. This is useful when you use a panic=... timeout and need the box quickly up again. + When hpet is specified, the NMI watchdog will be driven + by an HPET timer, if available in the system. Otherwise, + it falls back to the default implementation (perf or + architecture-specific). Specifying hpet has no effect + if the NMI watchdog is not enabled (either at build time + or via the command line). These settings can be accessed at runtime via the nmi_watchdog and hardlockup_panic sysctls. diff --git a/arch/x86/kernel/watchdog_hld_hpet.c b/arch/x86/kernel/watchdog_hld_hpet.c index 3effdbf29095..4413d5fb94f4 100644 --- a/arch/x86/kernel/watchdog_hld_hpet.c +++ b/arch/x86/kernel/watchdog_hld_hpet.c @@ -379,6 +379,28 @@ void hardlockup_detector_hpet_start(void) enable_timer(hld_data); } +/** + * hardlockup_detector_hpet_setup() - Parse command-line parameters + * @str: A string containing the kernel command line + * + * Parse the nmi_watchdog parameter from the kernel command line. If + * selected by the user, use this implementation to detect hardlockups. + */ +static int __init hardlockup_detector_hpet_setup(char *str) +{ + if (!str) + return -EINVAL; + + if (parse_option_str(str, "hpet")) + hardlockup_use_hpet = true; + + if (!nmi_watchdog_user_enabled && hardlockup_use_hpet) + pr_err("Selecting HPET NMI watchdog has no effect with NMI watchdog disabled\n"); + + return 0; +} +early_param("nmi_watchdog", hardlockup_detector_hpet_setup); + /** * hardlockup_detector_hpet_init() - Initialize the hardlockup detector * -- 2.17.1