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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,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 2E0A2C43219 for ; Tue, 30 Apr 2019 02:18:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02EEA21655 for ; Tue, 30 Apr 2019 02:18:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729919AbfD3CSE (ORCPT ); Mon, 29 Apr 2019 22:18:04 -0400 Received: from mga04.intel.com ([192.55.52.120]:60208 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729803AbfD3CSE (ORCPT ); Mon, 29 Apr 2019 22:18:04 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Apr 2019 19:18:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,412,1549958400"; d="scan'208";a="295651240" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga004.jf.intel.com with ESMTP; 29 Apr 2019 19:18:00 -0700 Cc: baolu.lu@linux.intel.com, David Woodhouse , Joerg Roedel , kevin.tian@intel.com, ashok.raj@intel.com, dima@arista.com, tmurphy@arista.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jacob.jun.pan@intel.com Subject: Re: [PATCH v3 5/8] iommu/vt-d: Implement def_domain_type iommu ops entry To: Christoph Hellwig References: <20190429020925.18136-1-baolu.lu@linux.intel.com> <20190429020925.18136-6-baolu.lu@linux.intel.com> <20190429200338.GA8412@infradead.org> From: Lu Baolu Message-ID: <9c1d1e16-fdab-0494-8720-97ff20013da4@linux.intel.com> Date: Tue, 30 Apr 2019 10:11:42 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190429200338.GA8412@infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Christoph, On 4/30/19 4:03 AM, Christoph Hellwig wrote: >> @@ -3631,35 +3607,30 @@ static int iommu_no_mapping(struct device *dev) >> if (iommu_dummy(dev)) >> return 1; >> >> - if (!iommu_identity_mapping) >> - return 0; >> - > > FYI, iommu_no_mapping has been refactored in for-next: > > https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/commit/?h=x86/vt-d&id=48b2c937ea37a3bece0094b46450ed5267525289 Oh, yes! Thanks for letting me know this. Will rebase the code. > >> found = identity_mapping(dev); >> if (found) { >> + /* >> + * If the device's dma_mask is less than the system's memory >> + * size then this is not a candidate for identity mapping. >> + */ >> + u64 dma_mask = *dev->dma_mask; >> + >> + if (dev->coherent_dma_mask && >> + dev->coherent_dma_mask < dma_mask) >> + dma_mask = dev->coherent_dma_mask; >> + >> + if (dma_mask < dma_get_required_mask(dev)) { > > I know this is mostly existing code moved around, but it really needs > some fixing. For one dma_get_required_mask is supposed to return the > required to not bounce mask for the given device. E.g. for a device > behind an iommu it should always just return 32-bit. If you really > want to check vs system memory please call dma_direct_get_required_mask > without the dma_ops indirection. > > Second I don't even think we need to check the coherent_dma_mask, > dma_direct is pretty good at always finding memory even without > an iommu. > > Third this doesn't take take the bus_dma_mask into account. > > This probably should just be: > > if (min(*dev->dma_mask, dev->bus_dma_mask) < > dma_direct_get_required_mask(dev)) { Agreed and will add this in the next version. Best regards, Lu Baolu