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_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 1B131ECDE43 for ; Fri, 19 Oct 2018 06:53:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE3E62086E for ; Fri, 19 Oct 2018 06:53:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE3E62086E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726967AbeJSO5m (ORCPT ); Fri, 19 Oct 2018 10:57:42 -0400 Received: from verein.lst.de ([213.95.11.211]:43608 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726465AbeJSO5m (ORCPT ); Fri, 19 Oct 2018 10:57:42 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id 7B12B68C76; Fri, 19 Oct 2018 08:52:58 +0200 (CEST) Date: Fri, 19 Oct 2018 08:52:58 +0200 From: Christoph Hellwig To: Konrad Rzeszutek Wilk Cc: Robin Murphy , Christoph Hellwig , Will Deacon , Catalin Marinas , linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 07/10] swiotlb: refactor swiotlb_map_page Message-ID: <20181019065258.GA29249@lst.de> References: <20181008080246.20543-1-hch@lst.de> <20181008080246.20543-8-hch@lst.de> <35016142-f06d-e424-5afe-6026b6d57eda@arm.com> <20181019003715.GI1251@char.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181019003715.GI1251@char.us.oracle.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 18, 2018 at 08:37:15PM -0400, Konrad Rzeszutek Wilk wrote: > > > + if (!dma_capable(dev, dma_addr, size) || > > > + swiotlb_force == SWIOTLB_FORCE) { > > > + trace_swiotlb_bounced(dev, dma_addr, size, swiotlb_force); > > > + dma_addr = swiotlb_bounce_page(dev, &phys, size, dir, attrs); > > > + } > > > > FWIW I prefer the inverse condition and early return of the original code > > here, which also then allows a tail-call to swiotlb_bounce_page() (and saves > > a couple of lines), but it's no biggie. > > > > Reviewed-by: Robin Murphy > > I agree with Robin - it certainly makes it easier to read. > > With that small change: > Reviewed-by: Konrad Rzeszutek Wilk So I did this edit, and in this patch it does indeed look much cleaner. But in patch 9 we introduce the cache maintainance, and have to invert the condition again if we don't want a goto mess: --- >From e840ec23360788d54a8ebd2ebc7cd0f0ef8bdb01 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 19 Oct 2018 08:51:53 +0200 Subject: swiotlb: add support for non-coherent DMA Handle architectures that are not cache coherent directly in the main swiotlb code by calling arch_sync_dma_for_{device,cpu} in all the right places from the various dma_map/unmap/sync methods when the device is non-coherent. Because swiotlb now uses dma_direct_alloc for the coherent allocation that side is already taken care of by the dma-direct code calling into arch_dma_{alloc,free} for devices that are non-coherent. Signed-off-by: Christoph Hellwig --- kernel/dma/swiotlb.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 1a01b0ac0a5e..ebecaf255ea2 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -21,6 +21,7 @@ #include #include +#include #include #include #include @@ -671,11 +672,17 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page, * we can safely return the device addr and not worry about bounce * buffering it. */ - if (dma_capable(dev, dev_addr, size) && swiotlb_force != SWIOTLB_FORCE) - return dev_addr; + if (!dma_capable(dev, dev_addr, size) || + swiotlb_force == SWIOTLB_FORCE) { + trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); + dev_addr = swiotlb_bounce_page(dev, &phys, size, dir, attrs); + } + + if (!dev_is_dma_coherent(dev) && + (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0) + arch_sync_dma_for_device(dev, phys, size, dir); - trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); - return swiotlb_bounce_page(dev, &phys, size, dir, attrs); + return dev_addr; } /* @@ -694,6 +701,10 @@ void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, BUG_ON(dir == DMA_NONE); + if (!dev_is_dma_coherent(hwdev) && + (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0) + arch_sync_dma_for_cpu(hwdev, paddr, size, dir); + if (is_swiotlb_buffer(paddr)) { swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs); return; @@ -730,15 +741,17 @@ swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr, BUG_ON(dir == DMA_NONE); - if (is_swiotlb_buffer(paddr)) { + if (!dev_is_dma_coherent(hwdev) && target == SYNC_FOR_CPU) + arch_sync_dma_for_cpu(hwdev, paddr, size, dir); + + if (is_swiotlb_buffer(paddr)) swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target); - return; - } - if (dir != DMA_FROM_DEVICE) - return; + if (!dev_is_dma_coherent(hwdev) && target == SYNC_FOR_DEVICE) + arch_sync_dma_for_device(hwdev, paddr, size, dir); - dma_mark_clean(phys_to_virt(paddr), size); + if (!is_swiotlb_buffer(paddr) && dir == DMA_FROM_DEVICE) + dma_mark_clean(phys_to_virt(paddr), size); } void -- 2.19.1