[PATCH] iommu/dma-iommu: respect established iova region limits

From: Nate Watterson
Date: Wed Jul 13 2016 - 12:43:12 EST

In the current dma-iommu implementation, the upper limit used when
allocating iovas is based on the calling device's dma_mask without
considering the potentially more restrictive iova limits established
in iommu_dma_init_domain. To ensure that iovas are allocated within
the expected iova region, this patch adds logic in __alloc_iova to
clip input dma_limit values that are out of bounds.

Signed-off-by: Nate Watterson <nwatters@xxxxxxxxxxxxxx>
drivers/iommu/dma-iommu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index ea5a9eb..2066066 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -157,11 +157,14 @@ static struct iova *__alloc_iova(struct iova_domain *iovad, size_t size,
unsigned long shift = iova_shift(iovad);
unsigned long length = iova_align(iovad, size) >> shift;

+ /* Respect the upper limit established in iommu_dma_init_domain */
+ dma_limit = min_t(dma_addr_t, dma_limit >> shift, iovad->dma_32bit_pfn);
* Enforce size-alignment to be safe - there could perhaps be an
* attribute to control this per-device, or at least per-domain...
- return alloc_iova(iovad, length, dma_limit >> shift, true);
+ return alloc_iova(iovad, length, dma_limit, true);

/* The IOVA allocator knows what we mapped, so just unmap whatever that was */
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