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>

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4d6ec44..94f305d 100644 (file)
--- 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) {