linux-kernel - [PATCH 2/2] dma-mapping: force unencryped devices are always addressing limited

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Date:   Wed,  4 Dec 2019 14:03:39 +0100
From:   Christoph Hellwig <hch@....de>
To:     Thomas Hellstrom <thellstrom@...are.com>
Cc:     Christian König <christian.koenig@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        iommu@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] dma-mapping: force unencryped devices are always addressing limited

Devices that are forced to DMA through swiotlb need to be treated as if
they are addressing limited.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 include/linux/dma-direct.h | 1 +
 kernel/dma/direct.c        | 8 ++++++--
 kernel/dma/mapping.c       | 3 +++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 24b8684aa21d..83aac21434c6 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -85,4 +85,5 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs);
 int dma_direct_supported(struct device *dev, u64 mask);
+bool dma_direct_addressing_limited(struct device *dev);
 #endif /* _LINUX_DMA_DIRECT_H */
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 6af7ae83c4ad..450f3abe5cb5 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -497,11 +497,15 @@ int dma_direct_supported(struct device *dev, u64 mask)
 	return mask >= __phys_to_dma(dev, min_mask);
 }
 
+bool dma_direct_addressing_limited(struct device *dev)
+{
+	return force_dma_unencrypted(dev) || swiotlb_force == SWIOTLB_FORCE;
+}
+
 size_t dma_direct_max_mapping_size(struct device *dev)
 {
 	/* If SWIOTLB is active, use its maximum mapping size */
-	if (is_swiotlb_active() &&
-	    (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE))
+	if (is_swiotlb_active() && dma_addressing_limited(dev))
 		return swiotlb_max_mapping_size(dev);
 	return SIZE_MAX;
 }
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 1dbe6d725962..ebc60633d89a 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -416,6 +416,9 @@ EXPORT_SYMBOL_GPL(dma_get_merge_boundary);
  */
 bool dma_addressing_limited(struct device *dev)
 {
+	if (dma_is_direct(get_dma_ops(dev)) &&
+	    dma_direct_addressing_limited(dev))
+		return true;
 	return min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <
 			    dma_get_required_mask(dev);
 }
-- 
2.20.1