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=-2.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 27F1EC43219 for ; Tue, 30 Apr 2019 18:05:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E074821734 for ; Tue, 30 Apr 2019 18:05:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556647508; bh=B39rAXs2hA5NMD+MHibPmm2x4OPWNDSHHLCgPam4oSU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=nB0T86STvH7Q8341RKWJcl3JeohALqCMgzxfDJ7m+iuTtc+o3VQs8+qpqFREG3U1j ztqi6QqRddGwyUhcegaC5A8zFZ/AGFfQOhhb5ir8cdAwCSOAW6wlaQnl/Itx//oJCp bySfZikJWvUxI/PJ2YP/L7be9NpOaTqANlE+op1g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726073AbfD3SFH (ORCPT ); Tue, 30 Apr 2019 14:05:07 -0400 Received: from mga18.intel.com ([134.134.136.126]:49225 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725950AbfD3SFH (ORCPT ); Tue, 30 Apr 2019 14:05:07 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Apr 2019 11:05:06 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,414,1549958400"; d="scan'208";a="138785887" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga008.jf.intel.com with ESMTP; 30 Apr 2019 11:05:05 -0700 Date: Tue, 30 Apr 2019 11:59:17 -0600 From: Keith Busch To: Alex Williamson Cc: Sinan Kaya , Bjorn Helgaas , mr.nuke.me@gmail.com, linux-pci@vger.kernel.org, austin_bolen@dell.com, alex_gagniuc@dellteam.com, keith.busch@intel.com, Shyam_Iyer@Dell.com, lukas@wunner.de, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] PCI: Add link_change error handler and vfio-pci user Message-ID: <20190430175917.GA25654@localhost.localdomain> References: <155605909349.3575.13433421148215616375.stgit@gimli.home> <20190424175758.GC244134@google.com> <20190429085104.728aee75@x1.home> <76169da9-36cd-6754-41e7-47c8ef668648@kernel.org> <20190429105926.209d17d3@x1.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190429105926.209d17d3@x1.home> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, Apr 29, 2019 at 10:59:26AM -0600, Alex Williamson wrote: > On Mon, 29 Apr 2019 09:45:28 -0700 > Sinan Kaya wrote: > > > On 4/29/2019 10:51 AM, Alex Williamson wrote: > > > So where do we go from here? I agree that dmesg is not necessarily a > > > great choice for these sorts of events and if they went somewhere else, > > > maybe I wouldn't have the same concerns about them generating user > > > confusion or contributing to DoS vectors from userspace drivers. As it > > > is though, we have known cases where benign events generate confusing > > > logging messages, which seems like a regression. Drivers didn't ask > > > for a link_change handler, but nor did they ask that the link state to > > > their device be monitored so closely. Maybe this not only needs some > > > sort of change to the logging mechanism, but also an opt-in by the > > > driver if they don't expect runtime link changes. Thanks, > > > > Is there anyway to detect autonomous hardware management support and > > not report link state changes in that situation? > > > > I thought there were some capability bits for these. > > Not that we can find, this doesn't trigger the separate autonomous > bandwidth notification interrupt. Thanks, I think the only control is to disable automomous lane and link rate changes. When set, any changes to either should only be in response to errors, so enabling those controls might be the right thing to do with this feature.