From: David Stevens <steve...@chromium.org> Calling the iommu_dma_sync_*_for_cpu functions during unmap can cause two copies out of the swiotlb buffer. Fold __iommu_dma_unmap_swiotlb into iommu_dma_unmap_page, and directly call arch_sync_dma_for_cpu instead of iommu_dma_sync_single_for_cpu to avoid this double sync. With this refactor, calling iommu_dma_sync_sg_for_cpu for untrusted devices in iommu_dma_unmap_sg is also no longer necessary, so move that invocation later in the function.
Signed-off-by: David Stevens <steve...@chromium.org> --- drivers/iommu/dma-iommu.c | 42 +++++++++++++++++---------------------- 1 file changed, 18 insertions(+), 24 deletions(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index e9119ff93535..f7da4934f7e6 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -493,23 +493,6 @@ static void __iommu_dma_unmap(struct device *dev, dma_addr_t dma_addr, iommu_dma_free_iova(cookie, dma_addr, size, iotlb_gather.freelist); } -static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr, - size_t size, enum dma_data_direction dir, - unsigned long attrs) -{ - struct iommu_domain *domain = iommu_get_dma_domain(dev); - phys_addr_t phys; - - phys = iommu_iova_to_phys(domain, dma_addr); - if (WARN_ON(!phys)) - return; - - __iommu_dma_unmap(dev, dma_addr, size); - - if (unlikely(is_swiotlb_buffer(phys))) - swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs); -} - static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys, size_t size, int prot, u64 dma_mask) { @@ -845,9 +828,20 @@ 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); + struct iommu_domain *domain = iommu_get_dma_domain(dev); + phys_addr_t phys; + + phys = iommu_iova_to_phys(domain, dma_handle); + 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_handle, size); + + if (unlikely(is_swiotlb_buffer(phys))) + swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs); } /* @@ -932,7 +926,7 @@ static void iommu_dma_unmap_sg_swiotlb(struct device *dev, struct scatterlist *s int i; for_each_sg(sg, s, nents, i) - __iommu_dma_unmap_swiotlb(dev, sg_dma_address(s), + iommu_dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir, attrs); } @@ -1053,14 +1047,14 @@ 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.rc1.237.g0d66db33f3-goog _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu