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iommu/arm-smmu-v3: Use WRITE_ONCE() when changing validity of an STE

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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>
This commit is contained in:
Will Deacon 2020-01-15 15:21:47 +00:00
parent 73af06f589
commit d71e01716b
1 changed files with 2 additions and 1 deletions
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3
drivers/iommu/arm-smmu-v3.c
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@ -1873,7 +1873,8 @@ 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 */