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 B72C2C432C3 for ; Tue, 26 Nov 2019 09:13:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E83420678 for ; Tue, 26 Nov 2019 09:13:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727426AbfKZJNY (ORCPT ); Tue, 26 Nov 2019 04:13:24 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:2113 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727028AbfKZJNX (ORCPT ); Tue, 26 Nov 2019 04:13:23 -0500 Received: from lhreml706-cah.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id 35295FC91DF0DEC22361; Tue, 26 Nov 2019 09:13:22 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by lhreml706-cah.china.huawei.com (10.201.108.47) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 26 Nov 2019 09:13:21 +0000 Received: from [127.0.0.1] (10.202.226.46) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Tue, 26 Nov 2019 09:13:21 +0000 Subject: Re: [PATCH v3 09/14] iommu/arm-smmu: Prevent forced unbinding of Arm SMMU drivers To: Will Deacon , , CC: Jean-Philippe Brucker , Jordan Crouse , Bjorn Helgaas , "Saravana Kannan" , Greg Kroah-Hartman , "Isaac J. Manjarres" , Robin Murphy , Lorenzo Pieralisi , Joerg Roedel References: <20191121114918.2293-1-will@kernel.org> <20191121114918.2293-10-will@kernel.org> From: John Garry Message-ID: <5c91d467-5e59-482b-8f4f-e0cfa3db9028@huawei.com> Date: Tue, 26 Nov 2019 09:13:20 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20191121114918.2293-10-will@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.46] X-ClientProxiedBy: lhreml720-chm.china.huawei.com (10.201.108.71) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/11/2019 11:49, Will Deacon wrote: > Forcefully unbinding the Arm SMMU drivers is a pretty dangerous operation, > since it will likely lead to catastrophic failure for any DMA devices > mastering through the SMMU being unbound. When the driver then attempts > to "handle" the fatal faults, it's very easy to trip over dead data > structures, leading to use-after-free. > > On John's machine, he reports that the machine was "unusable" due to > loss of the storage controller following a forced unbind of the SMMUv3 > driver: > > | # cd ./bus/platform/drivers/arm-smmu-v3 > | # echo arm-smmu-v3.0.auto > unbind > | hisi_sas_v2_hw HISI0162:01: CQE_AXI_W_ERR (0x800) found! > | platform arm-smmu-v3.0.auto: CMD_SYNC timeout at 0x00000146 > | [hwprod 0x00000146, hwcons 0x00000000] > > Prevent this forced unbinding of the drivers by setting "suppress_bind_attrs" > to true. This seems a reasonable approach for now. BTW, I'll give this series a spin this week, which again looks to be your iommu/module branch, excluding the new IORT patch. Cheers, John > > Link: https://lore.kernel.org/lkml/06dfd385-1af0-3106-4cc5-6a5b8e864759@huawei.com > Reported-by: John Garry > Signed-off-by: Will Deacon > --- > drivers/iommu/arm-smmu-v3.c | 5 +++-- > drivers/iommu/arm-smmu.c | 7 ++++--- > 2 files changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c > index 2ad8e2ca0583..3fd75abce3bb 100644 > --- a/drivers/iommu/arm-smmu-v3.c > +++ b/drivers/iommu/arm-smmu-v3.c > @@ -3700,8 +3700,9 @@ MODULE_DEVICE_TABLE(of, arm_smmu_of_match); > > static struct platform_driver arm_smmu_driver = { > .driver = { > - .name = "arm-smmu-v3", > - .of_match_table = of_match_ptr(arm_smmu_of_match), > + .name = "arm-smmu-v3", > + .of_match_table = of_match_ptr(arm_smmu_of_match), > + .suppress_bind_attrs = true, > }, > .probe = arm_smmu_device_probe, > .remove = arm_smmu_device_remove, > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 53bbe0663b9e..d6c83bd69555 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -2237,9 +2237,10 @@ static const struct dev_pm_ops arm_smmu_pm_ops = { > > static struct platform_driver arm_smmu_driver = { > .driver = { > - .name = "arm-smmu", > - .of_match_table = of_match_ptr(arm_smmu_of_match), > - .pm = &arm_smmu_pm_ops, > + .name = "arm-smmu", > + .of_match_table = of_match_ptr(arm_smmu_of_match), > + .pm = &arm_smmu_pm_ops, > + .suppress_bind_attrs = true, > }, > .probe = arm_smmu_device_probe, > .remove = arm_smmu_device_remove, >