linux-kernel - [PATCH v2 3/4] dma-iommu: pass SKIP_CPU

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Date:   Fri,  9 Jul 2021 12:35:01 +0900
From:   David Stevens <stevensd@...omium.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Tom Murphy <murphyt7@....ie>, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, David Stevens <stevensd@...omium.org>
Subject: [PATCH v2 3/4] dma-iommu: pass SKIP_CPU_SYNC to swiotlb unmap

From: David Stevens <stevensd@...omium.org>

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 <stevensd@...omium.org>
---
 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);
 }
 
 static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
-- 
2.32.0.93.g670b81a890-goog