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 C9D24C43334 for ; Tue, 21 Jun 2022 08:54:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345003AbiFUIyz (ORCPT ); Tue, 21 Jun 2022 04:54:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348465AbiFUIyl (ORCPT ); Tue, 21 Jun 2022 04:54:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C5B626ACA; Tue, 21 Jun 2022 01:54:40 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 05E72614E6; Tue, 21 Jun 2022 08:54:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B03ADC3411C; Tue, 21 Jun 2022 08:54:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655801679; bh=stOJe6Yy2xjGc5GXNNTGn9kaJkwY1JpspK8KOB4uxx0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KCTrCaUXgRpWTvpAB4Hn9pCQ0nVvRQ8SFBS77UtpNg0k0obRA+v3fIPp80pSLnZfn WF5g6hzW+JUhCcFneEfOGuQPktDhG2r0foiv6ouWnUK9oLyV5i74PIcy8AjGls1FDS dN1/ean6Zhb9xoNCMRqdIKIvhMOTY5v0WkUWnTr0= Date: Tue, 21 Jun 2022 10:54:35 +0200 From: Greg Kroah-Hartman To: Marc Zyngier Cc: Sebastian Ene , Rob Herring , Arnd Bergmann , Dragan Cvetic , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, will@kernel.org, vdonnefort@google.com, Guenter Roeck Subject: Re: [PATCH v7 2/2] misc: Add a mechanism to detect stalls on guest vCPUs Message-ID: References: <20220621080308.3952915-1-sebastianene@google.com> <20220621080308.3952915-3-sebastianene@google.com> <6b5bb5e69888f69fcfdcb8c9c2fd2660@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6b5bb5e69888f69fcfdcb8c9c2fd2660@kernel.org> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, Jun 21, 2022 at 09:44:35AM +0100, Marc Zyngier wrote: > On 2022-06-21 09:27, Greg Kroah-Hartman wrote: > > On Tue, Jun 21, 2022 at 08:03:09AM +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/vcpu_stall_detector.c | 222 > > > +++++++++++++++++++++++++++++ > > > 3 files changed, 235 insertions(+) > > > create mode 100644 drivers/misc/vcpu_stall_detector.c > > > > > > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig > > > index 41d2bb0ae23a..e15c85d74c4b 100644 > > > --- a/drivers/misc/Kconfig > > > +++ b/drivers/misc/Kconfig > > > @@ -483,6 +483,18 @@ config OPEN_DICE > > > > > > If unsure, say N. > > > > > > +config VCPU_STALL_DETECTOR > > > + tristate "VCPU stall detector" > > > + select LOCKUP_DETECTOR > > > + help > > > + Detect CPU locks on a kvm 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. > > > + To compile this driver as a module, choose M here: the > > > + module will be called vcpu_stall_detector. > > > > Should this depend on KVM_GUEST? > > Not all architectures have KVM_GUEST, and arm64 has no use for it. Ah, I thought this was a requirement (or created a better guest image) for use under KVM. Nevermind then... thanks, greg k-h