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[3.8.y.z,extended,stable] Patch "iommu/amd: Only unmap large pages from the first pte" has been added to staging queue

Message ID 1374015235-26934-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa July 16, 2013, 10:53 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    iommu/amd: Only unmap large pages from the first pte

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

From a08328707b9b712c54a0af3e048ad28ea254c34d Mon Sep 17 00:00:00 2001
From: Alex Williamson <alex.williamson@redhat.com>
Date: Fri, 21 Jun 2013 14:33:19 -0600
Subject: iommu/amd: Only unmap large pages from the first pte

commit 60d0ca3cfd199b6612bbbbf4999a3470dad38bb1 upstream.

If we use a large mapping, the expectation is that only unmaps from
the first pte in the superpage are supported.  Unmaps from offsets
into the superpage should fail (ie. return zero sized unmap).  In the
current code, unmapping from an offset clears the size of the full
mapping starting from an offset.  For instance, if we map a 16k
physically contiguous range at IOVA 0x0 with a large page, then
attempt to unmap 4k at offset 12k, 4 ptes are cleared (12k - 28k) and
the unmap returns 16k unmapped.  This potentially incorrectly clears
valid mappings and confuses drivers like VFIO that use the unmap size
to release pinned pages.

Fix by refusing to unmap from offsets into the page.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/iommu/amd_iommu.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--
1.8.1.2
diff mbox

Patch

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 409b171..895902e6 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1508,6 +1508,10 @@  static unsigned long iommu_unmap_page(struct protection_domain *dom,

 			/* Large PTE found which maps this address */
 			unmap_size = PTE_PAGE_SIZE(*pte);
+
+			/* Only unmap from the first pte in the page */
+			if ((unmap_size - 1) & bus_addr)
+				break;
 			count      = PAGE_SIZE_PTE_COUNT(unmap_size);
 			for (i = 0; i < count; i++)
 				pte[i] = 0ULL;
@@ -1517,7 +1521,7 @@  static unsigned long iommu_unmap_page(struct protection_domain *dom,
 		unmapped += unmap_size;
 	}

-	BUG_ON(!is_power_of_2(unmapped));
+	BUG_ON(unmapped && !is_power_of_2(unmapped));

 	return unmapped;
 }