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 79932C35247 for ; Wed, 5 Feb 2020 01:28:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5674D214AF for ; Wed, 5 Feb 2020 01:28:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727778AbgBEB2N (ORCPT ); Tue, 4 Feb 2020 20:28:13 -0500 Received: from mga03.intel.com ([134.134.136.65]:45636 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727674AbgBEB2N (ORCPT ); Tue, 4 Feb 2020 20:28:13 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Feb 2020 17:28:11 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,403,1574150400"; d="scan'208";a="225690656" Received: from jingyilu-mobl2.ccr.corp.intel.com (HELO [10.254.209.127]) ([10.254.209.127]) by fmsmga008.fm.intel.com with ESMTP; 04 Feb 2020 17:28:10 -0800 Subject: Re: [PATCH] iommu/intel-iommu: set as DUMMY_DEVICE_DOMAIN_INFO if no IOMMU To: Jian-Hong Pan Cc: David Woodhouse , Joerg Roedel , iommu@lists.linux-foundation.org, Linux Kernel , Linux Upstreaming Team References: <20200203091009.196658-1-jian-hong@endlessm.com> From: Lu Baolu Message-ID: <948da337-128f-22ae-7b2e-730b4b8da446@linux.intel.com> Date: Wed, 5 Feb 2020 09:28:09 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2020/2/4 17:25, Jian-Hong Pan wrote: > Lu Baolu 於 2020年2月4日 週二 下午2:11寫道： >> >> Hi, >> >> On 2020/2/3 17:10, Jian-Hong Pan wrote: >>> If the device has no IOMMU, it still invokes iommu_need_mapping during >>> intel_alloc_coherent. However, iommu_need_mapping can only check the >>> device is DUMMY_DEVICE_DOMAIN_INFO or not. This patch marks the device >>> is a DUMMY_DEVICE_DOMAIN_INFO if the device has no IOMMU. >>> >>> Signed-off-by: Jian-Hong Pan >>> --- >>> drivers/iommu/intel-iommu.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c >>> index 35a4a3abedc6..878bc986a015 100644 >>> --- a/drivers/iommu/intel-iommu.c >>> +++ b/drivers/iommu/intel-iommu.c >>> @@ -5612,8 +5612,10 @@ static int intel_iommu_add_device(struct device *dev) >>> int ret; >>> >>> iommu = device_to_iommu(dev, &bus, &devfn); >>> - if (!iommu) >>> + if (!iommu) { >>> + dev->archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO; >> >> Is this a DMA capable device? > > Do you mean is the device in DMA Remapping table? > Dump DMAR from ACPI table. The device is not in the table. > So, it does not support DMAR, Intel IOMMU. > > Or, should device_to_iommu be invoked in iommu_need_mapping to check > IOMMU feature again? > Normally intel_iommu_add_device() should only be called for PCI devices and APCI name space devices (reported in ACPI/DMAR table). In both cases, device_to_iommu() should always return a corresponding iommu. I just tried to understand why it failed for your case. Best regards, baolu