Commit 628bf55b authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

iommu/arm-smmu: Force identity domains for legacy binding 



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: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/9805e4c492cb972bdcdd57999d2d001a2d8b5aab.1652171938.git.robin.murphy@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 5ca21615

drivers/iommu/arm/arm-smmu/arm-smmu.c

+3 −0
Original line number Diff line number Diff line
@@ -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);