diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index 0b99d4a06f74..1b0c412566e5 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -214,24 +214,14 @@ static void iommu_full(struct device *dev, size_t size, int dir)
 static inline int
 need_iommu(struct device *dev, unsigned long addr, size_t size)
 {
-	u64 mask = *dev->dma_mask;
-	int high = addr + size > mask;
-	int mmu = high;
-
-	if (force_iommu)
-		mmu = 1;
-
-	return mmu;
+	return force_iommu ||
+		!is_buffer_dma_capable(*dev->dma_mask, addr, size);
 }
 
 static inline int
 nonforced_iommu(struct device *dev, unsigned long addr, size_t size)
 {
-	u64 mask = *dev->dma_mask;
-	int high = addr + size > mask;
-	int mmu = high;
-
-	return mmu;
+	return !is_buffer_dma_capable(*dev->dma_mask, addr, size);
 }
 
 /* Map a single continuous physical area into the IOMMU.