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Subject[PATCH v3 3/5] intel-iommu: integrate DMA CMA
Date
This adds support for the DMA Contiguous Memory Allocator for intel-iommu.
This change enables dma_alloc_coherent() to allocate big contiguous
memory.

It is achieved in the same way as nommu_dma_ops currently does, i.e.
trying to allocate memory by dma_alloc_from_contiguous() and alloc_pages()
is used as a fallback.

Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: x86@kernel.org
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* Changes from v2
- Fix gfp flags check for __GFP_ATOMIC, reported by Marek Szyprowski
- Rebased on current Linus tree

drivers/iommu/intel-iommu.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index cdb97c4..78c68cb 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3185,7 +3185,7 @@ static void *intel_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
struct dma_attrs *attrs)
{
- void *vaddr;
+ struct page *page = NULL;
int order;

size = PAGE_ALIGN(size);
@@ -3200,17 +3200,31 @@ static void *intel_alloc_coherent(struct device *dev, size_t size,
flags |= GFP_DMA32;
}

- vaddr = (void *)__get_free_pages(flags, order);
- if (!vaddr)
+ if (flags & __GFP_WAIT) {
+ unsigned int count = size >> PAGE_SHIFT;
+
+ page = dma_alloc_from_contiguous(dev, count, order);
+ if (page && iommu_no_mapping(dev) &&
+ page_to_phys(page) + size > dev->coherent_dma_mask) {
+ dma_release_from_contiguous(dev, page, count);
+ page = NULL;
+ }
+ }
+
+ if (!page)
+ page = alloc_pages(flags, order);
+ if (!page)
return NULL;
- memset(vaddr, 0, size);
+ memset(page_address(page), 0, size);

- *dma_handle = __intel_map_single(dev, virt_to_bus(vaddr), size,
+ *dma_handle = __intel_map_single(dev, page_to_phys(page), size,
DMA_BIDIRECTIONAL,
dev->coherent_dma_mask);
if (*dma_handle)
- return vaddr;
- free_pages((unsigned long)vaddr, order);
+ return page_address(page);
+ if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
+ __free_pages(page, order);
+
return NULL;
}

@@ -3218,12 +3232,14 @@ static void intel_free_coherent(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle, struct dma_attrs *attrs)
{
int order;
+ struct page *page = virt_to_page(vaddr);

size = PAGE_ALIGN(size);
order = get_order(size);

intel_unmap_page(dev, dma_handle, size, DMA_BIDIRECTIONAL, NULL);
- free_pages((unsigned long)vaddr, order);
+ if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
+ __free_pages(page, order);
}

static void intel_unmap_sg(struct device *dev, struct scatterlist *sglist,
--
1.8.3.2


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