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=-10.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 DBA04C4338F for ; Thu, 29 Jul 2021 12:42:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBF7960F0F for ; Thu, 29 Jul 2021 12:42:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237219AbhG2MmL (ORCPT ); Thu, 29 Jul 2021 08:42:11 -0400 Received: from mga07.intel.com ([134.134.136.100]:28495 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234459AbhG2MmK (ORCPT ); Thu, 29 Jul 2021 08:42:10 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10059"; a="276650385" X-IronPort-AV: E=Sophos;i="5.84,278,1620716400"; d="scan'208";a="276650385" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2021 05:42:06 -0700 X-IronPort-AV: E=Sophos;i="5.84,278,1620716400"; d="scan'208";a="518185758" Received: from blu2-mobl3.ccr.corp.intel.com (HELO [10.254.209.5]) ([10.254.209.5]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2021 05:42:04 -0700 Cc: baolu.lu@linux.intel.com, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, suravee.suthikulpanit@amd.com, john.garry@huawei.com, dianders@chromium.org Subject: Re: [PATCH v2 18/24] iommu: Express DMA strictness via the domain type To: Robin Murphy , joro@8bytes.org, will@kernel.org References: <50bee17e9248ccfccb33a10238210d4ff4f4cf4d.1627468309.git.robin.murphy@arm.com> From: Lu Baolu Message-ID: Date: Thu, 29 Jul 2021 20:42:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/7/29 17:36, Robin Murphy wrote: > On 2021-07-29 08:13, Lu Baolu wrote: >> Hi Robin, >> >> On 7/28/21 11:58 PM, Robin Murphy wrote: >>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >>> index 982545234cf3..eecb5657de69 100644 >>> --- a/drivers/iommu/iommu.c >>> +++ b/drivers/iommu/iommu.c >>> @@ -136,6 +136,9 @@ static int __init iommu_subsys_init(void) >>>           } >>>       } >>> +    if (!iommu_default_passthrough() && !iommu_dma_strict) >>> +        iommu_def_domain_type = IOMMU_DOMAIN_DMA_FQ; >> >> iommu_dma_strict could be changed later by the vendor iommu driver via >> iommu_set_dma_strict(). This seems not to be the right place to set >> iommu_def_domain_type. > > Ah yes, good catch once again, thanks! > > I think this *is* the right place to initially set it to honour the > command-line option, since that matches what we do for passthrough. > However also like passthrough we'll need to keep things in sync if it's > updated later, like this: > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 87d7b299436e..593d4555bc57 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -359,6 +359,8 @@ early_param("iommu.strict", iommu_dma_setup); >  void iommu_set_dma_strict(void) >  { >         iommu_dma_strict = true; > +       if (iommu_def_domain_type == IOMMU_DOMAIN_DMA_FQ) > +               iommu_def_domain_type = IOMMU_DOMAIN_DMA; >  } > >  static ssize_t iommu_group_attr_show(struct kobject *kobj, > > > Does that seem reasonable? I'm not sure there's any cleaner way to do it > since we don't want to inadvertently clobber the default type if the > user has given us something funky like "intel_iommu=strict > iommu.passthrough=1". Yeah! It's reasonable as far as I can see. Best regards, baolu > > Cheers, > Robin. > >> >>> + >>>       pr_info("Default domain type: %s %s\n", >>>           iommu_domain_type_str(iommu_def_domain_type), >>>           (iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ? >> >> Best regards, >> baolu