Patch "iommu/io-pgtable-arm-v7s: Fix attributes when splitting blocks" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

iommu/io-pgtable-arm-v7s: Fix attributes when splitting blocks

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
iommu-io-pgtable-arm-v7s-fix-attributes-when-splitting-blocks.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Robin Murphy <[email protected]>
Date: Thu, 11 Aug 2016 17:44:05 +0100
Subject: iommu/io-pgtable-arm-v7s: Fix attributes when splitting blocks

From: Robin Murphy <[email protected]>

commit e633fc7a1347528c3b4a6bbdeb41f5d63988242c upstream.

Due to the attribute bits being all over the place in the different types of short-descriptor PTEs, when remapping an existing entry, e.g. splitting a section into pages, we take the approach of decomposing the PTE attributes back to the IOMMU API flags to start from scratch.

On inspection, though, the existing code seems to have got the read-only bit backwards and ignored the XN bit. How embarrassing...

Fortunately the primary user so far, the Mediatek IOMMU, both never splits blocks (because it only serves non-overlapping DMA API calls) and also ignores permissions anyway, but let's put things right before any future users trip up.

---
 drivers/iommu/io-pgtable-arm-v7s.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -286,12 +286,14 @@ static int arm_v7s_pte_to_prot(arm_v7s_i
 	int prot = IOMMU_READ;
 	arm_v7s_iopte attr = pte >> ARM_V7S_ATTR_SHIFT(lvl);
 
-	if (attr & ARM_V7S_PTE_AP_RDONLY)
+	if (!(attr & ARM_V7S_PTE_AP_RDONLY))
 		prot |= IOMMU_WRITE;
 	if ((attr & (ARM_V7S_TEX_MASK << ARM_V7S_TEX_SHIFT)) == 0)
 		prot |= IOMMU_MMIO;
 	else if (pte & ARM_V7S_ATTR_C)
 		prot |= IOMMU_CACHE;
+	if (pte & ARM_V7S_ATTR_XN(lvl))
+		prot |= IOMMU_NOEXEC;
 
 	return prot;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/iommu-io-pgtable-arm-v7s-fix-attributes-when-splitting-blocks.patch queue-4.7/iommu-arm-smmu-don-t-bug-if-we-find-aborting-stes-with-disable_bypass.patch queue-4.7/iommu-dma-don-t-put-uninitialised-iova-domains.patch