iommu/arm-smmu-v3: Fix incorrect return in arm_smmu_attach_dev

After commit 48e7b8e ("iommu/arm-smmu-v3: Remove
arm_smmu_domain_finalise() during attach"), an error code is not
returned on the attach path when the smmu does not match with the
domain. This causes problems with VFIO because
vfio_iommu_type1_attach_group() relies on this check to determine domain
compatability.

Re-instate the -EINVAL return value when the SMMU doesn't match on the
device attach path.

Fixes: 48e7b8e ("iommu/arm-smmu-v3: Remove arm_smmu_domain_finalise() during attach")
Signed-off-by: Qinxin Xia <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: Qinxin Xia

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2953,7 +2953,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	smmu = master->smmu;
 
 	if (smmu_domain->smmu != smmu)
-		return ret;
+		return -EINVAL;
 
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
 		cdptr = arm_smmu_alloc_cd_ptr(master, IOMMU_NO_PASID);