[PATCH 15/21] dma-iommu: don't remap contiguous allocations for coherent devices

[Christoph Hellwig]

There is no need to remap for pte attributes, or for a virtually
contiguous address, so just don't do it.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 drivers/iommu/dma-iommu.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 445d1c163cae..dd28452ab3c2 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1048,10 +1048,10 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
 
 		addr = iommu_dma_alloc_contiguous(dev, iosize, handle, gfp,
 				attrs);
-		if (!addr)
-			return NULL;
-		page = virt_to_page(addr);
+		if (coherent || !addr)
+			return addr;
 
+		page = virt_to_page(addr);
 		addr = dma_common_contiguous_remap(page, size, VM_USERMAP, prot,
 				__builtin_return_address(0));
 		if (!addr) {
@@ -1059,8 +1059,7 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
 			return NULL;
 		}
 
-		if (!coherent)
-			arch_dma_prep_coherent(page, iosize);
+		arch_dma_prep_coherent(page, iosize);
 	} else {
 		addr = iommu_dma_alloc_remap(dev, iosize, handle, gfp, attrs);
 	}
-- 
2.20.1