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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 CFEFAC3A5A1 for ; Fri, 23 Aug 2019 01:52:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A574A233A0 for ; Fri, 23 Aug 2019 01:52:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388289AbfHWBwY (ORCPT ); Thu, 22 Aug 2019 21:52:24 -0400 Received: from mga05.intel.com ([192.55.52.43]:25107 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733139AbfHWBwY (ORCPT ); Thu, 22 Aug 2019 21:52:24 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Aug 2019 18:52:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,419,1559545200"; d="scan'208";a="173330337" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga008.jf.intel.com with ESMTP; 22 Aug 2019 18:52:21 -0700 Cc: baolu.lu@linux.intel.com, 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 , David Woodhouse , Joerg Roedel References: <20190822142922.31526-1-janusz.krzysztofik@linux.intel.com> From: Lu Baolu Message-ID: <00f1a3a7-7ff6-e9a0-d9de-a177af6fd64b@linux.intel.com> Date: Fri, 23 Aug 2019 09:51:11 +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: <20190822142922.31526-1-janusz.krzysztofik@linux.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, 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 iommu/vt-d: Detach domain when move device out of group When removing a device from an iommu group, the domain should be detached from the device. Otherwise, the stale domain info will still be cached by the driver and the driver will refuse to attach any domain to the device again. Cc: Ashok Raj Cc: Jacob Pan Cc: Kevin Tian Fixes: b7297783c2bb6 ("iommu/vt-d: Remove duplicated code for device hotplug") Reported-and-tested-by: Vlad Buslov Suggested-by: Robin Murphy Link: https://lkml.org/lkml/2019/7/26/1133 Signed-off-by: Lu Baolu Signed-off-by: Joerg Roedel Best regards, Lu Baolu > > Signed-off-by: Janusz Krzysztofik > --- > drivers/iommu/intel-iommu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 12d094d08c0a..7cdcd0595408 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2477,6 +2477,9 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu, > if (info2) { > found = info2->domain; > info2->dev = dev; > + > + if (dev && !dev->archdata.iommu) > + dev->archdata.iommu = info2; > } > } > >