From 480494e28a5132f408bad8ef492bd4e8a4dfd0de Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 15 Jan 2020 15:21:47 +0000 Subject: [PATCH] iommu/arm-smmu-v3: Use WRITE_ONCE() when changing validity of an STE [ 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 Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- 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 ee8d48d863e1..ef6af714a7e6 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -1643,7 +1643,8 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid, STRTAB_STE_1_EATS_TRANS)); 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 */