Commit d71e0171 authored Jan 15, 2020 by Will Deacon

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



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>

parent 73af06f5

drivers/iommu/arm-smmu-v3.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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 */

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