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iommu/amd: Don't clear DTE flags when modifying it

PATCH New Joerg Roedel 1 participant 1 message Oct 20, 2015

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Stable branch IOMMU
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Joerg Roedel

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PATCH 1/1 iommu/amd: Don't clear DTE flags when modifying it

From: Joerg Roedel <[email protected]>

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-1/[email protected]>
Tested-by G. Richard Bellamy <rbellamy-1/[email protected]>
Cc [email protected]
Signed-off-by Joerg Roedel <[email protected]>
---
 drivers/iommu/amd_iommu.c       | 4 ++--
 drivers/iommu/amd_iommu_types.h | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)
drivers/iommu/amd_iommu.c +2 -2
index f82060e7..d44dc2b 100644
@@ -1974,8 +1974,8 @@ 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);
 }
drivers/iommu/amd_iommu_types.h +1 -0
index f659088..c9b6472 100644
@@ -295,6 +295,7 @@
 #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)
Signature · 1 line
1.9.1