iommu/arm-smmu: Treat IOMMU_DOMAIN_DMA as bypass for now

Until all upstream devices have their DMA ops swizzled to point at the
SMMU, we need to treat the IOMMU_DOMAIN_DMA domain as bypass to avoid
putting devices into an empty address space when detaching from VFIO.

Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index f21332a15040..2409e3bd3df2 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1094,6 +1094,13 @@ static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
         if (ret)
                 return ret == -EEXIST ? 0 : ret;
 
+        /*
+         * FIXME: This won't be needed once we have IOMMU-backed DMA ops
+         * for all devices behind the SMMU.
+         */
+        if (smmu_domain->domain.type == IOMMU_DOMAIN_DMA)
+                return 0;
+
         for (i = 0; i < cfg->num_streamids; ++i) {
                 u32 idx, s2cr;