AMD IOMMU: avoid unnecessary low zone allocation in alloc_coherent (13d9fead) · Commits · 戴 / test

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>

arch/x86/kernel/amd_iommu.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;

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