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Subject[PATCH 16/23] AMD IOMMU: avoid unnecessary low zone allocation in alloc_coherent
Date
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

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>
---
arch/x86/kernel/amd_iommu.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 8c97360..963b8bb 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;
--
1.5.6.4



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