From: David Stevens <stevensd@chromium.org>
To: Robin Murphy <robin.murphy@arm.com>, Christoph Hellwig <hch@lst.de>
Cc: linux-kernel@vger.kernel.org, Tom Murphy <murphyt7@tcd.ie>,
iommu@lists.linux-foundation.org,
David Stevens <stevensd@chromium.org>,
Rajat Jain <rajatja@google.com>, Will Deacon <will@kernel.org>
Subject: [PATCH v8 3/7] dma-iommu: skip extra sync during unmap w/swiotlb
Date: Wed, 29 Sep 2021 11:32:56 +0900 [thread overview]
Message-ID: <20210929023300.335969-4-stevensd@google.com> (raw)
In-Reply-To: <20210929023300.335969-1-stevensd@google.com>
From: David Stevens <stevensd@chromium.org>
Calling the iommu_dma_sync_*_for_cpu functions during unmap can cause
two copies out of the swiotlb buffer. Do the arch sync directly in
__iommu_dma_unmap_swiotlb instead to avoid this. This makes the call to
iommu_dma_sync_sg_for_cpu for untrusted devices in iommu_dma_unmap_sg no
longer necessary, so move that invocation later in the function.
Signed-off-by: David Stevens <stevensd@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/iommu/dma-iommu.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 19bebacbf178..027b489714b7 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -521,6 +521,9 @@ static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr,
if (WARN_ON(!phys))
return;
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && !dev_is_dma_coherent(dev))
+ arch_sync_dma_for_cpu(phys, size, dir);
+
__iommu_dma_unmap(dev, dma_addr, size);
if (unlikely(is_swiotlb_buffer(dev, phys)))
@@ -871,8 +874,6 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
size_t size, enum dma_data_direction dir, unsigned long attrs)
{
- if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
- iommu_dma_sync_single_for_cpu(dev, dma_handle, size, dir);
__iommu_dma_unmap_swiotlb(dev, dma_handle, size, dir, attrs);
}
@@ -1088,14 +1089,14 @@ static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
struct scatterlist *tmp;
int i;
- if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
- iommu_dma_sync_sg_for_cpu(dev, sg, nents, dir);
-
if (dev_is_untrusted(dev)) {
iommu_dma_unmap_sg_swiotlb(dev, sg, nents, dir, attrs);
return;
}
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ iommu_dma_sync_sg_for_cpu(dev, sg, nents, dir);
+
/*
* The scatterlist segments are mapped into a single
* contiguous IOVA allocation, so this is incredibly easy.
--
2.33.0.685.g46640cef36-goog
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iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-09-29 2:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 2:32 [PATCH v8 0/7] Fixes for dma-iommu swiotlb bounce buffers David Stevens
2021-09-29 2:32 ` [PATCH v8 1/7] dma-iommu: fix sync_sg with swiotlb David Stevens
2021-09-29 2:32 ` [PATCH v8 2/7] dma-iommu: fix arch_sync_dma for map David Stevens
2021-09-29 2:32 ` David Stevens [this message]
2021-09-29 2:32 ` [PATCH v8 4/7] dma-iommu: fold _swiotlb helpers into callers David Stevens
2021-09-29 2:32 ` [PATCH v8 5/7] dma-iommu: Check CONFIG_SWIOTLB more broadly David Stevens
2021-09-29 2:32 ` [PATCH v8 6/7] swiotlb: support aligned swiotlb buffers David Stevens
2021-09-29 2:33 ` [PATCH v8 7/7] dma-iommu: account for min_align_mask w/swiotlb David Stevens
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