From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 07/10] swiotlb: refactor swiotlb_map_page Date: Fri, 19 Oct 2018 08:52:58 +0200 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-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20181019003715.GI1251-he5eyhs8q0BAdwtm4QZOy9BPR1lH4CV8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Konrad Rzeszutek Wilk Cc: Catalin Marinas , Will Deacon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Robin Murphy , Christoph Hellwig , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.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