From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Wed, 27 May 2015 15:09:15 +0100 Subject: [PATCH 1/4] iommu/iova: Avoid over-allocating when size-aligned In-Reply-To: References: Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 negative padding makes no sense. CC: David Woodhouse Signed-off-by: Robin Murphy --- drivers/iommu/intel-iommu.c | 2 ++ drivers/iommu/iova.c | 23 ++++++----------------- 2 files changed, 8 insertions(+), 17 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 68d43be..ada1fb9 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -2910,6 +2910,8 @@ static struct iova *intel_alloc_iova(struct device *dev, /* Restrict dma_mask to the width that the iommu can handle */ dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw), dma_mask); + /* Ensure we reserve the whole size-aligned region */ + nrpages = __roundup_pow_of_two(nrpages); if (!dmar_forcedac && dma_mask > DMA_BIT_MASK(32)) { /* diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 9dd8208..2c4a51b 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -120,19 +120,14 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free) } } -/* Computes the padding size required, to make the - * the start address naturally aligned on its size +/* + * Computes the padding size required, to make the start address + * naturally aligned on the power-of-two order of its size */ -static int -iova_get_pad_size(int size, unsigned int limit_pfn) +static unsigned int +iova_get_pad_size(unsigned int size, unsigned int limit_pfn) { - unsigned int pad_size = 0; - unsigned int order = ilog2(size); - - if (order) - pad_size = (limit_pfn + 1) % (1 << order); - - return pad_size; + return (limit_pfn + 1 - size) & (__roundup_pow_of_two(size) - 1); } static int __alloc_and_insert_iova_range(struct iova_domain *iovad, @@ -264,12 +259,6 @@ alloc_iova(struct iova_domain *iovad, unsigned long size, if (!new_iova) return NULL; - /* If size aligned is set then round the size to - * to next power of two. - */ - if (size_aligned) - size = __roundup_pow_of_two(size); - ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn, new_iova, size_aligned); -- 1.9.1