[PATCH]: PCI: GART iommu alignment fixes

From: Prarit Bhargava
Date: Mon Jul 21 2008 - 10:15:50 EST

pci_alloc_consistent/dma_alloc_coherent is supposed to return size aligned

>From Documentation/DMA-mapping.txt:

"pci_alloc_consistent returns two values: the virtual address which you
can use to access it from the CPU and dma_handle which you pass to the

The cpu return address and the DMA bus master address are both
guaranteed to be aligned to the smallest PAGE_SIZE order which
is greater than or equal to the requested size. This invariant
exists (for example) to guarantee that if you allocate a chunk
which is smaller than or equal to 64 kilobytes, the extent of the
buffer you receive will not cross a 64K boundary."

Fix the GART's alloc_iommu code to return a size aligned address. Also fix
an incorrect alignment calculation in the iommu-helper code.

Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index faf3229..329718e 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -96,11 +96,12 @@ static unsigned long alloc_iommu(struct device *dev, int size)

spin_lock_irqsave(&iommu_bitmap_lock, flags);
offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, next_bit,
- size, base_index, boundary_size, 0);
+ size, base_index, boundary_size, size - 1);
if (offset == -1) {
need_flush = 1;
offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, 0,
- size, base_index, boundary_size, 0);
+ size, base_index, boundary_size,
+ size - 1);
if (offset != -1) {
set_bit_string(iommu_gart_bitmap, offset, size);
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index a3b8d4c..b970f1b 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -16,7 +16,7 @@ again:
index = find_next_zero_bit(map, size, start);

/* Align allocation */
- index = (index + align_mask) & ~align_mask;
+ index = (index + align_mask + 1) & ~align_mask;

end = index + nr;
if (end >= size)
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/