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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 A8F75C10F14 for ; Wed, 9 Oct 2019 02:47:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82D9220859 for ; Wed, 9 Oct 2019 02:47:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730091AbfJICrb (ORCPT ); Tue, 8 Oct 2019 22:47:31 -0400 Received: from mga02.intel.com ([134.134.136.20]:32127 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726490AbfJICrb (ORCPT ); Tue, 8 Oct 2019 22:47:31 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Oct 2019 19:47:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,273,1566889200"; d="scan'208";a="192748823" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by fmsmga008.fm.intel.com with ESMTP; 08 Oct 2019 19:47:28 -0700 Cc: baolu.lu@linux.intel.com, Christoph Hellwig Subject: Re: [PATCH] iommu/vt-d: Return the correct dma mask when we are bypassing the IOMMU To: Arvind Sankar , linux-kernel@vger.kernel.org References: <20191008143357.GA599223@rani.riverdale.lan> From: Lu Baolu Message-ID: <76d680ab-a454-4a69-597a-c0edbfc5014b@linux.intel.com> Date: Wed, 9 Oct 2019 10:45:15 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191008143357.GA599223@rani.riverdale.lan> 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, On 10/8/19 10:33 PM, Arvind Sankar wrote: > We must return a mask covering the full physical RAM when bypassing the > IOMMU mapping. Also, in iommu_need_mapping, we need to check using > dma_direct_get_required_mask to ensure that the device's dma_mask can > cover physical RAM before deciding to bypass IOMMU mapping. > > Fixes: 249baa547901 ("dma-mapping: provide a better default ->get_required_mask") > Reported-by: Arvind Sankar > Tested-by: Arvind Sankar > Originally-by: Christoph Hellwig > Signed-off-by: Christoph Hellwig > Fixed-by: Arvind Sankar > Signed-off-by: Arvind Sankar > --- > drivers/iommu/intel-iommu.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 3f974919d3bd..79e35b3180ac 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -3471,7 +3471,7 @@ static bool iommu_need_mapping(struct device *dev) > 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)) > + if (dma_mask >= dma_direct_get_required_mask(dev)) > return false; > > /* > @@ -3775,6 +3775,13 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele > return nelems; > } > > +static u64 intel_get_required_mask(struct device *dev) > +{ > + if (!iommu_need_mapping(dev)) > + return dma_direct_get_required_mask(dev); > + return DMA_BIT_MASK(32); Do you mind explaining why we always return 32 bit here? Best regards, Baolu > +} > + > static const struct dma_map_ops intel_dma_ops = { > .alloc = intel_alloc_coherent, > .free = intel_free_coherent, > @@ -3787,6 +3794,7 @@ static const struct dma_map_ops intel_dma_ops = { > .dma_supported = dma_direct_supported, > .mmap = dma_common_mmap, > .get_sgtable = dma_common_get_sgtable, > + .get_required_mask = intel_get_required_mask, > }; > > static void >