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From:   Nicolin Chen <nicolinc@nvidia.com>
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Subject: [PATCH v2 15/17] iommu/arm-smmu-v3: Implement arm_smmu_get_msi_mapping_domain
Date:   Tue, 9 May 2023 20:33:35 -0700
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In a 1-stage translation setup, a device is attached to an iommu_domain
(ARM_SMMU_DOMAIN_S1) that is a kernel-managed domain.

In a 2-stage translation setup, a device is attached to an iommu_domain
(ARM_SMMU_DOMAIN_S1) that is IOMMU_DOMAIN_NESTED type, which must have
a valid "s2" pointer for an iommu_domain (ARM_SMMU_DOMAIN_S2) that is
a kernel-managed domain.

The MSI mappings for dma-iommu core to use are located in a domain that
must be a kernel-managed one. Thus, add a function to return the correct
iommu_domain pointer accordingly.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

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 3d150924581f..5fe7fed825d0 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2095,6 +2095,17 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 	kfree(smmu_domain);
 }
 
+static struct iommu_domain *
+arm_smmu_get_msi_mapping_domain(struct iommu_domain *domain)
+{
+	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+
+	if (smmu_domain->s2)
+		return &smmu_domain->s2->domain;
+
+	return domain;
+}
+
 static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 				       struct arm_smmu_master *master,
 				       struct io_pgtable_cfg *pgtbl_cfg)
@@ -2976,6 +2987,7 @@ static void arm_smmu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
 static const struct iommu_domain_ops arm_smmu_nested_domain_ops = {
 	.attach_dev		= arm_smmu_attach_dev,
 	.free			= arm_smmu_domain_free,
+	.get_msi_mapping_domain	= arm_smmu_get_msi_mapping_domain,
 };
 
 /**
-- 
2.40.1