Add iommu_get_nesting() which allow to retrieve whether a domain
uses nested stages.

Signed-off-by: Eric Auger <eric.au...@redhat.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  8 ++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  8 ++++++++
 drivers/iommu/intel/iommu.c                 | 13 +++++++++++++
 drivers/iommu/iommu.c                       | 10 ++++++++++
 include/linux/iommu.h                       |  8 ++++++++
 5 files changed, 47 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 a388e318f86e..61477853a536 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2731,6 +2731,13 @@ static int arm_smmu_enable_nesting(struct iommu_domain 
*domain)
        return ret;
 }
 
+static bool arm_smmu_get_nesting(struct iommu_domain *domain)
+{
+       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+
+       return smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED;
+}
+
 static int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args *args)
 {
        return iommu_fwspec_add_ids(dev, args->args, 1);
@@ -2845,6 +2852,7 @@ static struct iommu_ops arm_smmu_ops = {
        .release_device         = arm_smmu_release_device,
        .device_group           = arm_smmu_device_group,
        .enable_nesting         = arm_smmu_enable_nesting,
+       .get_nesting            = arm_smmu_get_nesting,
        .of_xlate               = arm_smmu_of_xlate,
        .get_resv_regions       = arm_smmu_get_resv_regions,
        .put_resv_regions       = generic_iommu_put_resv_regions,
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c 
b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 4bc75c4ce402..167cf1d51279 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1522,6 +1522,13 @@ static int arm_smmu_enable_nesting(struct iommu_domain 
*domain)
        return ret;
 }
 
+static bool arm_smmu_get_nesting(struct iommu_domain *domain)
+{
+       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+
+       return smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED;
+}
+
 static int arm_smmu_set_pgtable_quirks(struct iommu_domain *domain,
                unsigned long quirks)
 {
@@ -1595,6 +1602,7 @@ static struct iommu_ops arm_smmu_ops = {
        .probe_finalize         = arm_smmu_probe_finalize,
        .device_group           = arm_smmu_device_group,
        .enable_nesting         = arm_smmu_enable_nesting,
+       .get_nesting            = arm_smmu_get_nesting,
        .set_pgtable_quirks     = arm_smmu_set_pgtable_quirks,
        .of_xlate               = arm_smmu_of_xlate,
        .get_resv_regions       = arm_smmu_get_resv_regions,
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d75f59ae28e6..e42767bd47f9 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5524,6 +5524,18 @@ intel_iommu_enable_nesting(struct iommu_domain *domain)
        return ret;
 }
 
+static bool intel_iommu_get_nesting(struct iommu_domain *domain)
+{
+       struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+       bool nesting;
+
+       spin_lock_irqsave(&device_domain_lock, flags);
+       nesting =  dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE &&
+                  !(dmar_domain->flags & DOMAIN_FLAG_USE_FIRST_LEVEL);
+       spin_unlock_irqrestore(&device_domain_lock, flags);
+       return nesting;
+}
+
 /*
  * Check that the device does not live on an external facing PCI port that is
  * marked as untrusted. Such devices should not be able to apply quirks and
@@ -5561,6 +5573,7 @@ const struct iommu_ops intel_iommu_ops = {
        .domain_alloc           = intel_iommu_domain_alloc,
        .domain_free            = intel_iommu_domain_free,
        .enable_nesting         = intel_iommu_enable_nesting,
+       .get_nesting            = intel_iommu_get_nesting,
        .attach_dev             = intel_iommu_attach_device,
        .detach_dev             = intel_iommu_detach_device,
        .aux_attach_dev         = intel_iommu_aux_attach_device,
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6033c263c6e6..3e639c4e8015 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2843,6 +2843,16 @@ int iommu_enable_nesting(struct iommu_domain *domain)
 }
 EXPORT_SYMBOL_GPL(iommu_enable_nesting);
 
+bool iommu_get_nesting(struct iommu_domain *domain)
+{
+       if (domain->type != IOMMU_DOMAIN_UNMANAGED)
+               return false;
+       if (!domain->ops->enable_nesting)
+               return false;
+       return domain->ops->get_nesting(domain);
+}
+EXPORT_SYMBOL_GPL(iommu_get_nesting);
+
 int iommu_set_pgtable_quirks(struct iommu_domain *domain,
                unsigned long quirk)
 {
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index e34a1b1c805b..846e19151f40 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -213,6 +213,7 @@ struct iommu_iotlb_gather {
  *                  group and attached to the groups domain
  * @device_group: find iommu group for a particular device
  * @enable_nesting: Enable nesting
+ * @get_nesting: get whether the domain uses nested stages
  * @set_pgtable_quirks: Set io page table quirks (IO_PGTABLE_QUIRK_*)
  * @get_resv_regions: Request list of reserved regions for a device
  * @put_resv_regions: Free list of reserved regions for a device
@@ -271,6 +272,7 @@ struct iommu_ops {
        void (*probe_finalize)(struct device *dev);
        struct iommu_group *(*device_group)(struct device *dev);
        int (*enable_nesting)(struct iommu_domain *domain);
+       bool (*get_nesting)(struct iommu_domain *domain);
        int (*set_pgtable_quirks)(struct iommu_domain *domain,
                                  unsigned long quirks);
 
@@ -690,6 +692,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev,
                                        void *drvdata);
 void iommu_sva_unbind_device(struct iommu_sva *handle);
 u32 iommu_sva_get_pasid(struct iommu_sva *handle);
+bool iommu_get_nesting(struct iommu_domain *domain);
 
 #else /* CONFIG_IOMMU_API */
 
@@ -1108,6 +1111,11 @@ static inline struct iommu_fwspec 
*dev_iommu_fwspec_get(struct device *dev)
 {
        return NULL;
 }
+
+static inline bool iommu_get_nesting(struct iommu_domain *domain)
+{
+       return false;
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
-- 
2.26.3

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