swiotlb: use coherent_dma_mask in alloc_coherent (1e74f300) · Commits · 戴 / test

Impact: fix DMA buffer allocation coherency bug in certain configs This patch fixes swiotlb to use dev->coherent_dma_mask in swiotlb_alloc_coherent(). coherent_dma_mask is a subset of dma_mask (equal to it most of the time), enumerating the address range that a given device is able to DMA to/from in a cache-coherent way. But currently, swiotlb uses dev->dma_mask in alloc_coherent() implicitly via address_needs_mapping(), but alloc_coherent is really supposed to use coherent_dma_mask. This bug could break drivers that uses smaller coherent_dma_mask than dma_mask (though the current code works for the majority that use the same mask for coherent_dma_mask and dma_mask). Signed-off-by:

FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: tony.luck@intel.com Signed-off-by:

Ingo Molnar <mingo@elte.hu>

lib/swiotlb.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -467,9 +467,13 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
		dma_addr_t dev_addr;
		void *ret;
		int order = get_order(size);
		u64 dma_mask = DMA_32BIT_MASK;

		if (hwdev && hwdev->coherent_dma_mask)
		dma_mask = hwdev->coherent_dma_mask;

		ret = (void *)__get_free_pages(flags, order);
		if (ret && address_needs_mapping(hwdev, virt_to_bus(ret), size)) {
		if (ret && !is_buffer_dma_capable(dma_mask, virt_to_bus(ret), size)) {
		/*
		* The allocated memory isn't reachable by the device.
		* Fall back on swiotlb_map_single().
		@@ -493,9 +497,9 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
		dev_addr = virt_to_bus(ret);

		/* Confirm address can be DMA'd by device */
		if (address_needs_mapping(hwdev, dev_addr, size)) {
		if (!is_buffer_dma_capable(dma_mask, dev_addr, size)) {
		printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
		(unsigned long long)*hwdev->dma_mask,
		(unsigned long long)dma_mask,
		(unsigned long long)dev_addr);

		/* DMA_TO_DEVICE to avoid memcpy in unmap_single */

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