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

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Message-Id: <20190327080448.5500-16-hch@lst.de>
Date:   Wed, 27 Mar 2019 09:04:42 +0100
From:   Christoph Hellwig <hch@....de>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 15/21] dma-iommu: don't remap contiguous allocations for coherent devices

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@....de>
---
 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