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From: David Stevens <stevensd@chromium.org>
To: Robin Murphy <robin.murphy@arm.com>, Christoph Hellwig <hch@lst.de>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Lu Baolu <baolu.lu@linux.intel.com>, Tom Murphy <murphyt7@tcd.ie>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	David Stevens <stevensd@chromium.org>
Subject: [PATCH v6 2/7] dma-iommu: fix arch_sync_dma for map
Date: Tue, 17 Aug 2021 10:38:47 +0900	[thread overview]
Message-ID: <20210817013852.3222824-3-stevensd@google.com> (raw)
In-Reply-To: <20210817013852.3222824-1-stevensd@google.com>

From: David Stevens <stevensd@chromium.org>

When calling arch_sync_dma, we need to pass it the memory that's
actually being used for dma. When using swiotlb bounce buffers, this is
the bounce buffer. Move arch_sync_dma into the __iommu_dma_map_swiotlb
helper, so it can use the bounce buffer address if necessary.

Now that iommu_dma_map_sg delegates to a function which takes care of
architectural syncing in the untrusted device case, the call to
iommu_dma_sync_sg_for_device can be moved so it only occurs for trusted
devices. Doing the sync for untrusted devices before mapping never
really worked, since it needs to be able to target swiotlb buffers.

This also moves the architectural sync to before the call to
__iommu_dma_map, to guarantee that untrusted devices can't see stale
data they shouldn't see.

Fixes: 82612d66d51d ("iommu: Allow the dma-iommu api to use bounce buffers")
Signed-off-by: David Stevens <stevensd@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/iommu/dma-iommu.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 968e0150c95e..8098ce593640 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -576,6 +576,9 @@ static dma_addr_t __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
 		memset(padding_start, 0, padding_size);
 	}
 
+	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		arch_sync_dma_for_device(phys, org_size, dir);
+
 	iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
 	if (iova == DMA_MAPPING_ERROR && is_swiotlb_buffer(phys))
 		swiotlb_tbl_unmap_single(dev, phys, org_size, dir, attrs);
@@ -842,14 +845,9 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 {
 	phys_addr_t phys = page_to_phys(page) + offset;
 	bool coherent = dev_is_dma_coherent(dev);
-	dma_addr_t dma_handle;
 
-	dma_handle = __iommu_dma_map_swiotlb(dev, phys, size, dma_get_mask(dev),
+	return __iommu_dma_map_swiotlb(dev, phys, size, dma_get_mask(dev),
 			coherent, dir, attrs);
-	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-	    dma_handle != DMA_MAPPING_ERROR)
-		arch_sync_dma_for_device(phys, size, dir);
-	return dma_handle;
 }
 
 static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
@@ -992,12 +990,12 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
 	    iommu_deferred_attach(dev, domain))
 		return 0;
 
-	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
-		iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
-
 	if (dev_is_untrusted(dev))
 		return iommu_dma_map_sg_swiotlb(dev, sg, nents, dir, attrs);
 
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
+
 	/*
 	 * Work out how much IOVA space we need, and align the segments to
 	 * IOVA granules for the IOMMU driver to handle. With some clever
-- 
2.33.0.rc1.237.g0d66db33f3-goog


  parent reply	other threads:[~2021-08-17  1:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-17  1:38 [PATCH v6 0/7] Fixes for dma-iommu swiotlb bounce buffers David Stevens
2021-08-17  1:38 ` [PATCH v6 1/7] dma-iommu: fix sync_sg with swiotlb David Stevens
2021-08-17  1:38 ` David Stevens [this message]
2021-08-19  8:59   ` [PATCH v6 2/7] dma-iommu: fix arch_sync_dma for map Robin Murphy
2021-08-17  1:38 ` [PATCH v6 3/7] dma-iommu: skip extra sync during unmap w/swiotlb David Stevens
2021-08-19  8:59   ` Robin Murphy
2021-08-17  1:38 ` [PATCH v6 4/7] dma-iommu: fold _swiotlb helpers into callers David Stevens
2021-08-19  9:00   ` Robin Murphy
2021-08-17  1:38 ` [PATCH v6 5/7] dma-iommu: Check CONFIG_SWIOTLB more broadly David Stevens
2021-08-17  1:38 ` [PATCH v6 6/7] swiotlb: support aligned swiotlb buffers David Stevens
2021-08-17  1:38 ` [PATCH v6 7/7] dma-iommu: account for min_align_mask David Stevens
2021-08-19  9:03   ` Robin Murphy
2021-08-19 10:05     ` David Stevens

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