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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3FACC4708F for ; Mon, 31 May 2021 09:22:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C989660E0B for ; Mon, 31 May 2021 09:22:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229550AbhEaJXx (ORCPT ); Mon, 31 May 2021 05:23:53 -0400 Received: from gecko.sbs.de ([194.138.37.40]:47132 "EHLO gecko.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229523AbhEaJXw (ORCPT ); Mon, 31 May 2021 05:23:52 -0400 Received: from mail2.sbs.de (mail2.sbs.de [192.129.41.66]) by gecko.sbs.de (8.15.2/8.15.2) with ESMTPS id 14V9LnZA016506 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 31 May 2021 11:21:50 +0200 Received: from [167.87.247.112] ([167.87.247.112]) by mail2.sbs.de (8.15.2/8.15.2) with ESMTP id 14V9I7T5008408; Mon, 31 May 2021 11:18:08 +0200 Subject: Re: [PATCH v2] watchdog: iTCO_wdt: Account for rebooting on second timeout From: Jan Kiszka To: Guenter Roeck Cc: Wim Van Sebroeck , linux-watchdog@vger.kernel.org, Linux Kernel Mailing List , Paolo Bonzini , Christian Storm , Andy Shevchenko References: <0b8bb307-d08b-41b5-696c-305cdac6789c@siemens.com> <20210530131947.GB2483596@roeck-us.net> <5bf45bf8-0cd6-a131-fe11-1651ed60e8cc@siemens.com> Message-ID: <4e407c28-ab9e-7093-49f4-f9b985269fdc@siemens.com> Date: Mon, 31 May 2021 11:18:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <5bf45bf8-0cd6-a131-fe11-1651ed60e8cc@siemens.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On 31.05.21 10:27, Jan Kiszka wrote: > On 30.05.21 15:19, Guenter Roeck wrote: >> On Sun, May 30, 2021 at 01:24:23PM +0200, Jan Kiszka wrote: >>> From: Jan Kiszka >>> >>> This was already attempted to fix via 1fccb73011ea: If the BIOS did not >>> enable TCO SMIs, the timer definitely needs to trigger twice in order to >>> cause a reboot. If TCO SMIs are on, as well as SMIs in general, we can >>> continue to assume that the BIOS will perform a reboot on the first >>> timeout. >>> >>> QEMU with its ICH9 and related BIOS falls into the former category, >>> currently taking twice the configured timeout in order to reboot the >>> machine. For iTCO version that fall under turn_SMI_watchdog_clear_off, >>> this is also true and was currently only addressed for v1, irrespective >>> of the turn_SMI_watchdog_clear_off value. >>> >>> Signed-off-by: Jan Kiszka >>> --- >>> >>> Changes in v2: >>> - consider GBL_SMI_EN as well >>> >>> drivers/watchdog/iTCO_wdt.c | 12 +++++++++--- >>> 1 file changed, 9 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c >>> index bf31d7b67a69..3f1324871cfd 100644 >>> --- a/drivers/watchdog/iTCO_wdt.c >>> +++ b/drivers/watchdog/iTCO_wdt.c >>> @@ -71,6 +71,8 @@ >>> #define TCOBASE(p) ((p)->tco_res->start) >>> /* SMI Control and Enable Register */ >>> #define SMI_EN(p) ((p)->smi_res->start) >>> +#define TCO_EN (1 << 13) >>> +#define GBL_SMI_EN (1 << 0) >>> >>> #define TCO_RLD(p) (TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */ >>> #define TCOv1_TMR(p) (TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/ >>> @@ -355,8 +357,12 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t) >>> >>> tmrval = seconds_to_ticks(p, t); >>> >>> - /* For TCO v1 the timer counts down twice before rebooting */ >>> - if (p->iTCO_version == 1) >>> + /* >>> + * If TCO SMIs are off, the timer counts down twice before rebooting. >>> + * Otherwise, the BIOS generally reboots when the SMI triggers. >>> + */ >>> + if (p->smi_res && >>> + (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN)) >>> tmrval /= 2; >> >> This expands the scope of this adjustment to all versions, while at the same >> time making it conditional for v1. Is this correct ? What for systems with v1 >> TCO where the above conditions are not met ? > > Yes, this is intended. You find the reference to "reboots on second > timeout" even in latest EHL datasheets (v6). > To make it clearer: By default, we disabled SMIs on v1, thus had to adjust the timeout there unconditionally. In QEMU (v2), the firmware does not enable SMI, and we failed to handle that. Conceptually, any platform on any (known) version that does not use TCO SMIs is affected. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux