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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F14DDC433EF for ; Fri, 29 Apr 2022 20:25:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345389AbiD2U3I (ORCPT ); Fri, 29 Apr 2022 16:29:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232546AbiD2U3G (ORCPT ); Fri, 29 Apr 2022 16:29:06 -0400 Received: from mail-oi1-f174.google.com (mail-oi1-f174.google.com [209.85.167.174]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42BE63C734; Fri, 29 Apr 2022 13:25:47 -0700 (PDT) Received: by mail-oi1-f174.google.com with SMTP id r1so9502005oie.4; Fri, 29 Apr 2022 13:25:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=TVAQuGhjd9n0kUWsH2GbUvhmDBHPRxTlldbJix1Anrg=; b=CeiDrd4FIXIhhIYXskh88hnDxjSqj5iZkpQkt9LRjm/GZS/XipdyPQsDZ/idWtCdPt IRrrVX0LFBIZcz3BZuILco7jQNkSNz/EGZhwc3j2E5efJ5Yk4TvcDk8m9FLArEqZy5jR 5Un0UM8If0PlDdrO6ml/R2ghjAvD7JUcxPY5RcNfY8baoTeMbRGB+6bqRAc7pPlp2MWe hj+62ut8OmwSVA59AZryIIbqe9aSg3FPpBBxsX2CSdNr7TthX7T9DwO9q9y808BXuCi8 V9oN7/uJ7m8vngkbR9QjQBpvOHw2qq7vzvSlynw1OwB1dY93CCvsz+HreFwutyRDFgsa T28w== X-Gm-Message-State: AOAM532CNjz4tNXCN85Le/JqMpWanm8UsiUx3fI6xUzSCO98rJfrANTV sG2JWP3WOuxUxSjywKpfDg== X-Google-Smtp-Source: ABdhPJy2MbnQXUPWfyt7SN9UKSlKCEDbzz/8Ju2fEu5V/tdV0sNBK9tYmlnWcNQUQgRQWENvDvnuTg== X-Received: by 2002:a05:6808:f8d:b0:325:1e81:ffe5 with SMTP id o13-20020a0568080f8d00b003251e81ffe5mr551243oiw.253.1651263946535; Fri, 29 Apr 2022 13:25:46 -0700 (PDT) Received: from robh.at.kernel.org (66-90-144-107.dyn.grandenetworks.net. [66.90.144.107]) by smtp.gmail.com with ESMTPSA id h3-20020a056870d24300b000e686d1386fsm3375710oac.9.2022.04.29.13.25.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Apr 2022 13:25:46 -0700 (PDT) Received: (nullmailer pid 2808184 invoked by uid 1000); Fri, 29 Apr 2022 20:25:45 -0000 Date: Fri, 29 Apr 2022 15:25:45 -0500 From: Rob Herring To: Sebastian Ene Cc: Greg Kroah-Hartman , Arnd Bergmann , Dragan Cvetic , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, maz@kernel.org, will@kernel.org, qperret@google.com, Guenter Roeck Subject: Re: [PATCH v4 0/2] Detect stalls on guest vCPUS Message-ID: References: <20220429083030.3241640-1-sebastianene@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220429083030.3241640-1-sebastianene@google.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, Apr 29, 2022 at 08:30:29AM +0000, Sebastian Ene wrote: > This adds a mechanism to detect stalls on the guest vCPUS by creating a > per CPU hrtimer which periodically 'pets' the host backend driver. > On a conventional watchdog-core driver, the userspace is responsible for > delivering the 'pet' events by writing to the particular /dev/watchdogN node. > In this case we require a strong thread affinity to be able to > account for lost time on a per vCPU basis. > > This device driver acts as a soft lockup detector by relying on the host > backend driver to measure the elapesed time between subsequent 'pet' events. > If the elapsed time doesn't match an expected value, the backend driver > decides that the guest vCPU is locked and resets the guest. The host > backend driver takes into account the time that the guest is not > running. The communication with the backend driver is done through MMIO > and the register layout of the virtual watchdog is described as part of > the backend driver changes. > > The host backend driver is implemented as part of: > https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3548817 > > Changelog v4: > - rename the source from vm-wdt.c -> vm-watchdog.c > - convert all the error logging calls from pr_* to dev_* calls > - rename the DTS node "clock" to "clock-frequency" Why do I have a v4 now when the discussion on v3 is not concluded. Give folks some time to respond. We're busy drinking from the firehose. Rob