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=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 2642EC19F34 for ; Mon, 2 Aug 2021 14:05:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1289E60527 for ; Mon, 2 Aug 2021 14:05:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237229AbhHBOEo (ORCPT ); Mon, 2 Aug 2021 10:04:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:41966 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235619AbhHBN5T (ORCPT ); Mon, 2 Aug 2021 09:57:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9D13161155; Mon, 2 Aug 2021 13:54:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627912490; bh=ffsZcqleS2Msj4hKWIBmJ4DPBk3NI1GngO6NeU0SeTU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VtSmunYUXbIIrXS3l/nVkmZXkowH6vo/7g7EKVHyGGAP/bs4NpsweEv1bYURFTDYP hPZkudv6Q+a1gVJLvSugGrJCXJGILZJXjQzxFBTiIxO+EwtizHV5Ph4vUtdeyue8i9 dkMBvitTmr3l0I5+q7p3nWeLK1b9uacCWjCeefWIm0rWNNa/2bRiT4DpgiNkpZkaKH uAJrliut8ve2C7rQIIMqyP5sSiyd+sOv9LtAQruboXcyd32Tn6PLVeBXRY3Ob2RSc8 n/n92HXPgxrkA9a9JptQmeZKFf4CSCofpomOhAAx+xF4xqHHhJZHAVliePCKrTO2Nf 6KwI1rx3CS2ag== Date: Mon, 2 Aug 2021 14:54:46 +0100 From: Will Deacon To: David Stevens Cc: Robin Murphy , Joerg Roedel , Lu Baolu , Tom Murphy , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/4] dma-iommu: pass SKIP_CPU_SYNC to swiotlb unmap Message-ID: <20210802135446.GE28547@willie-the-truck> References: <20210709033502.3545820-1-stevensd@google.com> <20210709033502.3545820-4-stevensd@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210709033502.3545820-4-stevensd@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 09, 2021 at 12:35:01PM +0900, David Stevens wrote: > From: David Stevens > > If SKIP_CPU_SYNC isn't already set, then iommu_dma_unmap_(page|sg) has > already called iommu_dma_sync_(single|sg)_for_cpu, so there is no need > to copy from the bounce buffer again. > > Signed-off-by: David Stevens > --- > drivers/iommu/dma-iommu.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index e79e274d2dc5..0a9a9a343e64 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -505,7 +505,8 @@ static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr, > __iommu_dma_unmap(dev, dma_addr, size); > > if (unlikely(is_swiotlb_buffer(phys))) > - swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs); > + swiotlb_tbl_unmap_single(dev, phys, size, dir, > + attrs | DMA_ATTR_SKIP_CPU_SYNC); > } I think it would be cleaner to drop DMA_ATTR_SKIP_CPU_SYNC in the callers once they've called iommu_dma_sync_*_for_cpu(). Will