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

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

From: Nate Watterson <nwatt...@codeaurora.org>


[ Upstream commit 810871c57011eb3e89e6768932757f169d666cd2 ]

To prevent corruption of the stage-1 context pointer field when
updating STEs, rebuild the entire containing dword instead of
clearing individual fields.

Signed-off-by: Nate Watterson <nwatt...@codeaurora.org>
Signed-off-by: Will Deacon <will.dea...@arm.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/iommu/arm-smmu-v3.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1040,13 +1040,8 @@ static void arm_smmu_write_strtab_ent(st
                }
        }
 
-       /* Nuke the existing Config, as we're going to rewrite it */
-       val &= ~(STRTAB_STE_0_CFG_MASK << STRTAB_STE_0_CFG_SHIFT);
-
-       if (ste->valid)
-               val |= STRTAB_STE_0_V;
-       else
-               val &= ~STRTAB_STE_0_V;
+       /* Nuke the existing STE_0 value, as we're going to rewrite it */
+       val = ste->valid ? STRTAB_STE_0_V : 0;
 
        if (ste->bypass) {
                val |= disable_bypass ? STRTAB_STE_0_CFG_ABORT
@@ -1081,7 +1076,6 @@ static void arm_smmu_write_strtab_ent(st
                val |= (ste->s1_cfg->cdptr_dma & STRTAB_STE_0_S1CTXPTR_MASK
                        << STRTAB_STE_0_S1CTXPTR_SHIFT) |
                        STRTAB_STE_0_CFG_S1_TRANS;
-
        }
 
        if (ste->s2_cfg) {


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