diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c index 690629457565..af330f513653 100644 --- a/drivers/iommu/io-pgtable-arm-v7s.c +++ b/drivers/iommu/io-pgtable-arm-v7s.c @@ -408,8 +408,12 @@ static arm_v7s_iopte arm_v7s_install_table(arm_v7s_iopte *table, if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS) new |= ARM_V7S_ATTR_NS_TABLE; - /* Ensure the table itself is visible before its PTE can be */ - wmb(); + /* + * Ensure the table itself is visible before its PTE can be. + * Whilst we could get away with cmpxchg64_release below, this + * doesn't have any ordering semantics when !CONFIG_SMP. + */ + dma_wmb(); old = cmpxchg_relaxed(ptep, curr, new); __arm_v7s_pte_sync(ptep, 1, cfg); diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index 52700fa958c2..b182039862c5 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -331,8 +331,12 @@ static arm_lpae_iopte arm_lpae_install_table(arm_lpae_iopte *table, if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS) new |= ARM_LPAE_PTE_NSTABLE; - /* Ensure the table itself is visible before its PTE can be */ - wmb(); + /* + * Ensure the table itself is visible before its PTE can be. + * Whilst we could get away with cmpxchg64_release below, this + * doesn't have any ordering semantics when !CONFIG_SMP. + */ + dma_wmb(); old = cmpxchg64_relaxed(ptep, curr, new);