iommu/arm-smmu-v3: Clear prior settings when updating STEs

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 <nwatters@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 2 insertions, 8 deletions

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4d6ec444a9d6..94f305db8739 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1042,13 +1042,8 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
                 }
         }
 
-        /* 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
@@ -1083,7 +1078,6 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
                 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) {