When mapping a non-page-aligned scatterlist entry, we copy the original
offset to the output DMA address before aligning it to hand off to
iommu_map_sg(), then later adding the IOVA page address portion to get
the final mapped address. However, when the IOVA page size is smaller
than the CPU page size, it is the offset within the IOVA page we want,
not that within the CPU page, which can easily be larger than an IOVA
page and thus result in an incorrect final address.
Fix the bug by taking only the IOVA-aligned part of the offset as the
basis of the DMA address, not the whole thing.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Doug reports that the equivalent page allocator on 32-bit ARM exhibits
particularly pathalogical behaviour under memory pressure when
fragmentation is high, where allocating a 4MB buffer takes tens of
seconds and the number of calls to alloc_pages() is over 9000![1]
We can drastically improve that situation without losing the other
benefits of high-order allocations when they would succeed, by assuming
memory pressure is relatively constant over the course of an allocation,
and not retrying allocations at orders we know to have failed before.
This way, the best-case behaviour remains unchanged, and in the worst
case we should see at most a dozen or so (MAX_ORDER - 1) failed attempts
before falling back to single pages for the remainder of the buffer.
[1]:http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/394660.html
Reported-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
dma-iommu.c was naughtily relying on an implicit transitive #include of
linux/vmalloc.h, which is apparently not present on some architectures.
Add that, plus a couple more headers for other functions which are used
similarly.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Taking inspiration from the existing arch/arm code, break out some
generic functions to interface the DMA-API to the IOMMU-API. This will
do the bulk of the heavy lifting for IOMMU-backed dma-mapping.
Since associating an IOVA allocator with an IOMMU domain is a fairly
common need, rather than introduce yet another private structure just to
do this for ourselves, extend the top-level struct iommu_domain with the
notion. A simple opaque cookie allows reuse by other IOMMU API users
with their various different incompatible allocator types.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
