linux-kernel - [PATCH 3.16.y-ckt 70/94] iommu/amd: Don't clear DTE flags when modifying it

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Message-Id: <1447409428-12178-71-git-send-email-luis.henriques@canonical.com>
Date:	Fri, 13 Nov 2015 10:10:04 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Joerg Roedel <jroedel@...e.de>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 70/94] iommu/amd: Don't clear DTE flags when modifying it

3.16.7-ckt20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joerg Roedel <jroedel@...e.de>

commit cbf3ccd09d683abf1cacd36e3640872ee912d99b upstream.

During device assignment/deassignment the flags in the DTE
get lost, which might cause spurious faults, for example
when the device tries to access the system management range.
Fix this by not clearing the flags with the rest of the DTE.

Reported-by: G. Richard Bellamy <rbellamy@...radigm.com>
Tested-by: G. Richard Bellamy <rbellamy@...radigm.com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/iommu/amd_iommu.c       | 4 ++--
 drivers/iommu/amd_iommu_types.h | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 706cbc5bd5cc..b4b133207505 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2152,8 +2152,8 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain, bool ats)
 static void clear_dte_entry(u16 devid)
 {
 	/* remove entry from the device table seen by the hardware */
-	amd_iommu_dev_table[devid].data[0] = IOMMU_PTE_P | IOMMU_PTE_TV;
-	amd_iommu_dev_table[devid].data[1] = 0;
+	amd_iommu_dev_table[devid].data[0]  = IOMMU_PTE_P | IOMMU_PTE_TV;
+	amd_iommu_dev_table[devid].data[1] &= DTE_FLAG_MASK;
 
 	amd_iommu_apply_erratum_63(devid);
 }
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index f1a5abf11acf..40b28381585a 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -289,6 +289,7 @@
 #define IOMMU_PTE_IR (1ULL << 61)
 #define IOMMU_PTE_IW (1ULL << 62)
 
+#define DTE_FLAG_MASK	(0x3ffULL << 32)
 #define DTE_FLAG_IOTLB	(0x01UL << 32)
 #define DTE_FLAG_GV	(0x01ULL << 55)
 #define DTE_GLX_SHIFT	(56)
--
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