linux-kernel - [PATCH] iommu/dma-iommu: properly respect configured address space size

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Date:   Mon, 07 Nov 2016 14:06:13 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH] iommu/dma-iommu: properly respect configured address space size

When one called iommu_dma_init_domain() with size smaller than device's
DMA mask, the alloc_iova() will not respect it and always assume that all
IOVA addresses will be allocated from the the (base ... dev->dma_mask) range.

This patch fixes this issue by taking the configured address space size
parameter into account (if it is smaller than the device's dma_mask).

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
 drivers/iommu/dma-iommu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index c5ab8667e6f2..8b4b72654359 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -212,11 +212,13 @@ static struct iova *__alloc_iova(struct iommu_domain *domain, size_t size,
 
 	if (domain->geometry.force_aperture)
 		dma_limit = min(dma_limit, domain->geometry.aperture_end);
+
+	dma_limit = min(dma_limit >> shift, (dma_addr_t)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 */
-- 
1.9.1