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 52A10C433F5 for ; Fri, 29 Apr 2022 08:51:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238619AbiD2Iyi (ORCPT ); Fri, 29 Apr 2022 04:54:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233789AbiD2Iyh (ORCPT ); Fri, 29 Apr 2022 04:54:37 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4087B7487C; Fri, 29 Apr 2022 01:51:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E27DDB8333A; Fri, 29 Apr 2022 08:51:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC821C385A4; Fri, 29 Apr 2022 08:51:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651222277; bh=YhaUE2RPVGeLkyq7yEjG6K0bBdymSkrTMQYmZsGskl0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vEs25PmQJXrQO1g6U/yOtbT+4P43FZC2j9UN/0kOYi/raFYOJnSh7eXfJ5Horfh/s +rNGImDhIdcWYjdDkr33prtnMN0bFzygp+SOefJeZJi9de6uqQjdPDGNMxgqb9R71I 7MCxCE0FmHNCs2CU07z1olyh1ksrrREH1PK250xM= Date: Fri, 29 Apr 2022 10:51:14 +0200 From: Greg Kroah-Hartman To: Sebastian Ene Cc: Rob Herring , 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 2/2] misc: Add a mechanism to detect stalls on guest vCPUs Message-ID: References: <20220429083030.3241640-1-sebastianene@google.com> <20220429083030.3241640-3-sebastianene@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220429083030.3241640-3-sebastianene@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 29, 2022 at 08:30:33AM +0000, Sebastian Ene wrote: > This driver creates per-cpu hrtimers which are required to do the > periodic 'pet' operation. 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. > > This part of the driver is the 'frontend' which is reponsible for > delivering the periodic 'pet' events, configuring the virtual peripheral > and listening for cpu hotplug events. The other part of the driver > handles the peripheral emulation and this part accounts for lost time by > looking at the /proc/{}/task/{}/stat entries and is located here: > https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3548817 > > Signed-off-by: Sebastian Ene > --- > drivers/misc/Kconfig | 12 +++ > drivers/misc/Makefile | 1 + > drivers/misc/vm-watchdog.c | 206 +++++++++++++++++++++++++++++++++++++ > 3 files changed, 219 insertions(+) > create mode 100644 drivers/misc/vm-watchdog.c > > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig > index 2b9572a6d114..26c3a99e269c 100644 > --- a/drivers/misc/Kconfig > +++ b/drivers/misc/Kconfig > @@ -493,6 +493,18 @@ config OPEN_DICE > > If unsure, say N. > > +config VM_WATCHDOG > + tristate "Virtual Machine Watchdog" > + select LOCKUP_DETECTOR > + help > + Detect CPU locks on the virtual machine. This driver relies on the > + hrtimers which are CPU-binded to do the 'pet' operation. When a vCPU > + has to do a 'pet', it exits the guest through MMIO write and the > + backend driver takes into account the lost ticks for this particular > + CPU. There's nothing to keep this tied to a virtual machine at all, right? You are just relying on some iomem address to be updated, so it should be a "generic_iomem_watchdog" driver as there's nothing specific to vms at all from what I can tell. thanks, greg k-h