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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 A2593C3A59E for ; Mon, 26 Aug 2019 08:30:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD9EE2080C for ; Mon, 26 Aug 2019 08:30:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730580AbfHZIa2 (ORCPT ); Mon, 26 Aug 2019 04:30:28 -0400 Received: from mga11.intel.com ([192.55.52.93]:46936 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729328AbfHZIa2 (ORCPT ); Mon, 26 Aug 2019 04:30:28 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Aug 2019 01:30:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,431,1559545200"; d="scan'208";a="379573481" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by fmsmga005.fm.intel.com with ESMTP; 26 Aug 2019 01:30:26 -0700 Cc: baolu.lu@linux.intel.com, David Woodhouse , Joerg Roedel , iommu@lists.linux-foundation.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?Micha=c5=82_Wajdeczko?= Subject: Re: [RFC PATCH] iommu/vt-d: Fix IOMMU field not populated on device hot re-plug To: Janusz Krzysztofik References: <20190822142922.31526-1-janusz.krzysztofik@linux.intel.com> <00f1a3a7-7ff6-e9a0-d9de-a177af6fd64b@linux.intel.com> <7536805.yzB8ZXLclH@jkrzyszt-desk.ger.corp.intel.com> From: Lu Baolu Message-ID: <790a4a20-7517-fe54-177d-850b9beeb88e@linux.intel.com> Date: Mon, 26 Aug 2019 16:29:12 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <7536805.yzB8ZXLclH@jkrzyszt-desk.ger.corp.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Janusz, On 8/26/19 4:15 PM, Janusz Krzysztofik wrote: > Hi Lu, > > On Friday, August 23, 2019 3:51:11 AM CEST Lu Baolu wrote: >> Hi, >> >> On 8/22/19 10:29 PM, Janusz Krzysztofik wrote: >>> When a perfectly working i915 device is hot unplugged (via sysfs) and >>> hot re-plugged again, its dev->archdata.iommu field is not populated >>> again with an IOMMU pointer. As a result, the device probe fails on >>> DMA mapping error during scratch page setup. >>> >>> It looks like that happens because devices are not detached from their >>> MMUIO bus before they are removed on device unplug. Then, when an >>> already registered device/IOMMU association is identified by the >>> reinstantiated device's bus and function IDs on IOMMU bus re-attach >>> attempt, the device's archdata is not populated with IOMMU information >>> and the bad happens. >>> >>> I'm not sure if this is a proper fix but it works for me so at least it >>> confirms correctness of my analysis results, I believe. So far I >>> haven't been able to identify a good place where the possibly missing >>> IOMMU bus detach on device unplug operation could be added. >> >> Which kernel version are you testing with? Does it contain below commit? >> >> commit 458b7c8e0dde12d140e3472b80919cbb9ae793f4 >> Author: Lu Baolu >> Date: Thu Aug 1 11:14:58 2019 +0800 > > I was using an internal branch based on drm-tip which didn't contain this > commit yet. Fortunately it has been already merged into drm-tip over last > weekend and has effectively fixed the issue. Thanks for testing this. Best regards, Lu Baolu