From: Robin Murphy Date: Tue, 10 May 2022 09:38:58 +0100 Subject: iommu/arm-smmu: Force identity domains for legacy binding Git-commit: 628bf55b620497a105f4963ee8fb84769f7e6bb4 Patch-mainline: v5.19-rc1 References: bsc#1205701 When using the legacy "mmu-masters" DT binding, we reject DMA domains since we have no guarantee of driver probe order and thus can't rely on client drivers getting the correct DMA ops. However, we can do better than fall back to the old no-default-domain behaviour now, by forcing an identity default domain instead. This also means that detaching from a VFIO domain can actually work - that looks to have been broken for over 6 years, so clearly isn't something that legacy binding users care about, but we may as well make the driver code make sense anyway. Suggested-by: Jason Gunthorpe Signed-off-by: Robin Murphy Link: https://lore.kernel.org/r/9805e4c492cb972bdcdd57999d2d001a2d8b5aab.1652171938.git.robin.murphy@arm.com Signed-off-by: Will Deacon Acked-by: Joerg Roedel --- drivers/iommu/arm/arm-smmu/arm-smmu.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c index 52b71f6aee3f..2ed3594f384e 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c @@ -1574,6 +1574,9 @@ static int arm_smmu_def_domain_type(struct device *dev) struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev); const struct arm_smmu_impl *impl = cfg->smmu->impl; + if (using_legacy_binding) + return IOMMU_DOMAIN_IDENTITY; + if (impl && impl->def_domain_type) return impl->def_domain_type(dev);