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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 79EE4C10F11 for ; Wed, 10 Apr 2019 05:28:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F3AD20850 for ; Wed, 10 Apr 2019 05:28:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727198AbfDJF21 (ORCPT ); Wed, 10 Apr 2019 01:28:27 -0400 Received: from mga05.intel.com ([192.55.52.43]:20412 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726693AbfDJF21 (ORCPT ); Wed, 10 Apr 2019 01:28:27 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Apr 2019 22:28:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,332,1549958400"; d="scan'208";a="130076506" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga007.jf.intel.com with ESMTP; 09 Apr 2019 22:28:25 -0700 Cc: baolu.lu@linux.intel.com, iommu@lists.linux-foundation.org, Tom Murphy , Dmitry Safonov , Jacob Pan , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/7] iommu/vt-d: Expose ISA direct mapping region via iommu_get_resv_regions To: James Sewart References: <0F0C82BE-86E5-4BAC-938C-6F7629E18D27@arista.com> <83B82113-8AE5-4B0C-A079-F389520525BD@arista.com> <445F31EA-20F3-481C-B1DF-8B163791FF8C@arista.com> <6C211BF1-B5A0-4821-AB42-092B573DE667@arista.com> <8B1FC0C7-9BAC-498D-B1F0-0138EACF75C2@arista.com> <9AECB54A-2DA7-4ABD-A9B5-0549E108D1AF@arista.com> From: Lu Baolu Message-ID: Date: Wed, 10 Apr 2019 13:22:30 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <9AECB54A-2DA7-4ABD-A9B5-0549E108D1AF@arista.com> 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 James, On 4/6/19 2:02 AM, James Sewart wrote: > Hey Lu, > > My bad, did some debugging on my end. The issue was swapping out > find_domain for iommu_get_domain_for_dev. It seems in some situations the > domain is not attached to the group but the device is expected to have the > domain still stored in its archdata. > > I’ve attached the final patch with find_domain unremoved which seems to > work in my testing. > Just looked into your v3 patch set and some thoughts from my end posted here just for your information. Let me post the problems we want to address. 1. When allocating a new group for a device, how should we determine the type of the default domain? 2. If we need to put a device into an existing group which uses a different type of domain from what the device desires to use, we might break the functionality of the device. My new thought is letting the iommu generic code to determine the default domain type (hence my proposed vendor specific default domain type patches could be dropped). If the default domain type is dynamical mapping, and later in iommu_no_mapping(), we determines that we must use an identity domain, we then call iommu_request_dm_for_dev(dev). If the default domain type is identity mapping, and later in iommu_no_mapping(), we determined that we must use a dynamical domain, we then call iommu_request_dma_domain_for_dev(dev). We already have iommu_request_dm_for_dev() in iommu.c. We only need to implement iommu_request_dma_domain_for_dev(). With this done, your patch titled "Create an IOMMU group for devices that require an identity map" could also be dropped. Any thoughts? > Cheers, > James. Best regards, Lu Baolu