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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 354FDECDE47 for ; Thu, 8 Nov 2018 21:52:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8825204FD for ; Thu, 8 Nov 2018 21:52:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E8825204FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727318AbeKIHaH (ORCPT ); Fri, 9 Nov 2018 02:30:07 -0500 Received: from mga12.intel.com ([192.55.52.136]:1865 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726875AbeKIHaG (ORCPT ); Fri, 9 Nov 2018 02:30:06 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Nov 2018 13:52:40 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,480,1534834800"; d="scan'208";a="90590978" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga008.jf.intel.com with ESMTP; 08 Nov 2018 13:52:39 -0800 Date: Thu, 8 Nov 2018 14:49:00 -0700 From: Keith Busch To: Bjorn Helgaas Cc: Alexandru Gagniuc , linux-pci@vger.kernel.org, alex_gagniuc@dellteam.com, austin_bolen@dell.com, shyam_iyer@dell.com, linux-kernel@vger.kernel.org, Jonathan Derrick , Greg Kroah-Hartman , Lukas Wunner , Russell Currey , Sam Bobroff , Oliver O'Halloran , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v2] PCI/MSI: Don't touch MSI bits when the PCI device is disconnected Message-ID: <20181108214900.GB2932@localhost.localdomain> References: <20180918221501.13112-1-mr.nuke.me@gmail.com> <20181107234257.GC41183@google.com> <20181108200855.GE41183@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181108200855.GE41183@google.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 08, 2018 at 02:09:17PM -0600, Bjorn Helgaas wrote: > > I'm having second thoughts about this. One thing I'm uncomfortable > with is that sprinkling pci_dev_is_disconnected() around feels ad hoc > instead of systematic, in the sense that I don't know how we convince > ourselves that this (and only this) is the correct place to put it. You know how the kernel provides ZERO_PAGE, wouldn't it be cool if we also had a ONES_PAGE and could remap all virtual addresses from a memory mapped device to that page on an ungraceful disconnect? I do not know how to accomplish that, so might just be crazy talk... But if it is possible, that would be a pretty nifty way to solve this problem.