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

An error is introduced in commit '48e7b8e284e5'. When the smmu
does not match with domain,an error code is not returned.
An example of an error scenario: In vfio_iommu_type1_attach_group,
vfio will try to match an existing compatible domain. During this process,
iommu invokes the attach_dev interface.The mismatched dev and domain
does not return an error code as expected.
As a result, an exception occurs when the vfio operates the smmu.

Fixes: 48e7b8e284e5 ("iommu/arm-smmu-v3: Remove arm_smmu_domain_finalise() during attach")
Signed-off-by: Qinxin Xia <xiaqinxin@huawei.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 358072b4e293..cb2698325809 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2932,7 +2932,7 @@ 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);

-- 
2.33.0

On Tue, 22 Apr 2025 19:29:51 +0800, Qinxin Xia wrote:

An error is introduced in commit '48e7b8e284e5'. When the smmu
does not match with domain,an error code is not returned.
An example of an error scenario: In vfio_iommu_type1_attach_group,
vfio will try to match an existing compatible domain. During this process,
iommu invokes the attach_dev interface.The mismatched dev and domain
does not return an error code as expected.
As a result, an exception occurs when the vfio operates the smmu.

[...]

Applied to iommu (arm/smmu/updates), thanks!

[1/1] iommu/arm-smmu-v3: Fix incorrect return in arm_smmu_attach_dev
      https://git.kernel.org/iommu/c/be5a2d3f8f97

Cheers,
-- 
Will

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