linux-kernel - [PATCH 3.4 83/92] iommu/amd: Don't clear DTE flags when modifying it

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Date:	Mon, 18 Apr 2016 18:46:28 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
	Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 83/92] iommu/amd: Don't clear DTE flags when modifying it

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

3.4.112-rc1 review patch.  If anyone has any objections, please let me know.

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


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: Zefan Li <lizefan@...wei.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 a55353c3..30e6d5f 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1931,8 +1931,8 @@ 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 c4ffacb..42f2090 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -277,6 +277,7 @@
 #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)
-- 
1.9.1