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> Link: https://lore.kernel.org/r/20210929023300.335969-4-stevensd@google.com Signed-off-by: Joerg Roedel <jroedel@suse.de>