From: Robin Murphy <robin.murphy@arm.com>
Date: Thu, 16 Jul 2015 18:40:12 +0000 (+0100)
Subject: iommu/iova: Avoid over-allocating when size-aligned
X-Git-Tag: omap-for-v4.3/fixes-rc5~54^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f6429c7cb59f28433253575cc8e3262eed63592;p=pandora-kernel.git

iommu/iova: Avoid over-allocating when size-aligned

Currently, allocating a size-aligned IOVA region quietly adjusts the
actual allocation size in the process, returning a rounded-up
power-of-two-sized allocation. This results in mismatched behaviour in
the IOMMU driver if the original size was not a power of two, where the
original size is mapped, but the rounded-up IOVA size is unmapped.

Whilst some IOMMUs will happily unmap already-unmapped pages, others
consider this an error, so fix it by computing the necessary alignment
padding without altering the actual allocation size. Also clean up by
making pad_size unsigned, since its callers always pass unsigned values
and negative padding makes little sense here anyway.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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