AMD IOMMU: avoid unnecessary low zone allocation in alloc_coherent

x86's common alloc_coherent (dma_alloc_coherent in dma-mapping.h) sets
up the gfp flag according to the device dma_mask but AMD IOMMU doesn't
need it for devices that the IOMMU can do virtual mappings for. This
patch avoids unnecessary low zone allocation.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index a34d8e915e3a..e4866660463e 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -1173,6 +1173,9 @@ static void *alloc_coherent(struct device *dev, size_t size,
         if (!check_device(dev))
                 return NULL;
 
+        if (!get_device_resources(dev, &iommu, &domain, &devid))
+                flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
+
         virt_addr = (void *)__get_free_pages(flag, get_order(size));
         if (!virt_addr)
                 return 0;
@@ -1180,8 +1183,6 @@ static void *alloc_coherent(struct device *dev, size_t size,
         memset(virt_addr, 0, size);
         paddr = virt_to_phys(virt_addr);
 
-        get_device_resources(dev, &iommu, &domain, &devid);
-
         if (!iommu || !domain) {
                 *dma_addr = (dma_addr_t)paddr;
                 return virt_addr;