From: Will Deacon will@kernel.org
[ Upstream commit d71e01716b3606a6648df7e5646ae12c75babde4 ]
If, for some bizarre reason, the compiler decided to split up the write of STE DWORD 0, we could end up making a partial structure valid.
Although this probably won't happen, follow the example of the context-descriptor code and use WRITE_ONCE() to ensure atomicity of the write.
Reported-by: Jean-Philippe Brucker jean-philippe@linaro.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/arm-smmu-v3.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index eb9937225d645..6c10f307a1c98 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -1090,7 +1090,8 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid, }
arm_smmu_sync_ste_for_sid(smmu, sid); - dst[0] = cpu_to_le64(val); + /* See comment in arm_smmu_write_ctx_desc() */ + WRITE_ONCE(dst[0], cpu_to_le64(val)); arm_smmu_sync_ste_for_sid(smmu, sid);
/* It's likely that we'll want to use the new STE soon */