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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 14AA6C433ED for ; Thu, 13 May 2021 03:11:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E76FE61411 for ; Thu, 13 May 2021 03:11:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230489AbhEMDM1 (ORCPT ); Wed, 12 May 2021 23:12:27 -0400 Received: from mga02.intel.com ([134.134.136.20]:29490 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230186AbhEMDM0 (ORCPT ); Wed, 12 May 2021 23:12:26 -0400 IronPort-SDR: iYhx8zu+pFss2K6oCaCNgvR605oJ/4B5mVE3ZUerynkdsmWtiBUJgMwhLICJ8kvoHlBCDX5Pye us52Pm+DEHbg== X-IronPort-AV: E=McAfee;i="6200,9189,9982"; a="186989707" X-IronPort-AV: E=Sophos;i="5.82,296,1613462400"; d="scan'208";a="186989707" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2021 20:11:12 -0700 IronPort-SDR: rYgEoMOfzV+LgG65pLR0vcGBSB+6puHbSyeU7qACrWjxPvcwfOCr8KkY6Sx2peHCyH3k/0tf/P uuEpxSDxI9YA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,296,1613462400"; d="scan'208";a="623088032" Received: from allen-box.sh.intel.com (HELO [10.239.159.128]) ([10.239.159.128]) by fmsmga006.fm.intel.com with ESMTP; 12 May 2021 20:11:09 -0700 Cc: baolu.lu@linux.intel.com, "Raj, Ashok" , "Kumar, Sanjay K" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "Pan, Jacob jun" Subject: Re: [PATCH 1/1] iommu/vt-d: Support asynchronous IOMMU nested capabilities To: "Tian, Kevin" , Joerg Roedel , Will Deacon References: <20210512070421.3472857-1-baolu.lu@linux.intel.com> <2eb677d1-14d7-c1dc-6dd4-179c11c76b10@linux.intel.com> From: Lu Baolu Message-ID: Date: Thu, 13 May 2021 11:10:22 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/13/21 10:26 AM, Tian, Kevin wrote: >> From: Lu Baolu >> Sent: Wednesday, May 12, 2021 7:31 PM >> >> Hi Kevin, >> >> On 5/12/21 4:30 PM, Tian, Kevin wrote: >>>> From: Lu Baolu >>>> Sent: Wednesday, May 12, 2021 3:04 PM >>>> >>>> Current VT-d implementation supports nested translation only if all >>>> underlying IOMMUs support the nested capability. This is unnecessary >>>> as the upper layer is allowed to create different containers and set >>>> them with different type of iommu backend. The IOMMU driver needs to >>>> guarantee that devices attached to a nested mode iommu_domain should >>>> support nested capabilility. >>> so the consistency check is now applied only to the IOMMUs that are >>> spanned by a given iommu_domain? >> Yes. >> >>>> Signed-off-by: Lu Baolu >>>> --- >>>> drivers/iommu/intel/iommu.c | 21 +++++++++++++++++++-- >>>> 1 file changed, 19 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >>>> index f1742da42478..1cd4840e6f9f 100644 >>>> --- a/drivers/iommu/intel/iommu.c >>>> +++ b/drivers/iommu/intel/iommu.c >>>> @@ -4755,6 +4755,13 @@ static int >> prepare_domain_attach_device(struct >>>> iommu_domain *domain, >>>> if (!iommu) >>>> return -ENODEV; >>>> >>>> + if ((dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE) && >>>> + !ecap_nest(iommu->ecap)) { >>>> + dev_err(dev, "%s: iommu not support nested translation\n", >>>> + iommu->name); >>>> + return -EINVAL; >>>> + } >>>> + >>>> /* check if this iommu agaw is sufficient for max mapped address */ >>>> addr_width = agaw_to_width(iommu->agaw); >>>> if (addr_width > cap_mgaw(iommu->cap)) >>>> @@ -5451,11 +5458,21 @@ static int >>>> intel_iommu_enable_nesting(struct iommu_domain *domain) >>>> { >>>> struct dmar_domain *dmar_domain = to_dmar_domain(domain); >>>> + struct dmar_drhd_unit *drhd; >>>> + struct intel_iommu *iommu; >>>> + bool has_nesting = false; >>>> unsigned long flags; >>>> - int ret = -ENODEV; >>>> + int ret = -EINVAL; >>>> + >>>> + for_each_active_iommu(iommu, drhd) >>>> + if (ecap_nest(iommu->ecap)) >>>> + has_nesting = true; >>>> + >>>> + if (!has_nesting) >>>> + return -ENODEV; >>> Isn't above still doing global consistency check? >> The logic is if nested mode is globally unsupported, return false. > why is this check required? anyway you already have the check when > prepare device attachment, and only at that point you have accurate > info for which iommu to be checked. This check looks meaningless > as even if some IOMMUs support nesting it doesn't mean the IOMMU > relevant to this domain support it. > Get you. It's really unnecessary. I will drop this check in the new version. Best regards, baolu