[PATCH v5 1/5] iommu: Add optional subdev in aux_at(de)tach ops

[Lu Baolu <baolu.lu@linux.intel.com>]

In the vfio/mdev use case of aux-domain, the subdevices are created from
the physical devices with IOMMU_DEV_FEAT_AUX enabled and the aux-domains
are attached to the subdevices through the iommu_ops.aux_attach_dev()
interface.

Current iommu_ops.aux_at(de)tach_dev() design only takes the aux-domain
and the physical device as the parameters, this is insufficient if we
want the vendor iommu drivers to learn the knowledge about relationships
between the aux-domains and the subdevices. Add a @subdev parameter to
iommu_ops.aux_at(de)tach_dev() interfaces so that a subdevice could be
opt-in.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 10 ++++++----
 drivers/iommu/iommu.c       | 26 +++++++++++++++++---------
 include/linux/iommu.h       |  6 ++++--
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 1b7d390beb68..86142ce32f21 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5353,8 +5353,9 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
 	return domain_add_dev_info(to_dmar_domain(domain), dev);
 }
 
-static int intel_iommu_aux_attach_device(struct iommu_domain *domain,
-					 struct device *dev)
+static int
+intel_iommu_aux_attach_device(struct iommu_domain *domain,
+			      struct device *dev, struct device *subdev)
 {
 	int ret;
 
@@ -5374,8 +5375,9 @@ static void intel_iommu_detach_device(struct iommu_domain *domain,
 	dmar_remove_one_dev_info(dev);
 }
 
-static void intel_iommu_aux_detach_device(struct iommu_domain *domain,
-					  struct device *dev)
+static void
+intel_iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev,
+			      struct device *subdev)
 {
 	aux_domain_remove_dev(to_dmar_domain(domain), dev);
 }
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6c14c88cd525..4c6e94682327 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2714,7 +2714,7 @@ bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat)
 EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
 
 /*
- * Aux-domain specific attach/detach.
+ * Aux-domain specific interfaces.
  *
  * Only works if iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) returns
  * true. Also, as long as domains are attached to a device through this
@@ -2722,36 +2722,44 @@ EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
  * (iommu_detach_device() can't fail, so we fail when trying to re-attach).
  * This should make us safe against a device being attached to a guest as a
  * whole while there are still pasid users on it (aux and sva).
+ *
+ * Some physical devices can be configured to generate several subdevices.
+ * The modern IOMMUs support the identification and isolation of these
+ * subdevices. Hence they could be passed through to users space. VFIO/mdev
+ * provides a generic framework for subdevice passthrough. Below interfaces
+ * support such use case. Generally, among the parameters of the following
+ * aux-domain specific functions, @physdev represents a physical device,
+ * and @subdev represents a subdevice.
  */
-int iommu_aux_attach_device(struct iommu_domain *domain, struct device *dev)
+int iommu_aux_attach_device(struct iommu_domain *domain, struct device *physdev)
 {
 	int ret = -ENODEV;
 
 	if (domain->ops->aux_attach_dev)
-		ret = domain->ops->aux_attach_dev(domain, dev);
+		ret = domain->ops->aux_attach_dev(domain, physdev, NULL);
 
 	if (!ret)
-		trace_attach_device_to_domain(dev);
+		trace_attach_device_to_domain(physdev);
 
 	return ret;
 }
 EXPORT_SYMBOL_GPL(iommu_aux_attach_device);
 
-void iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev)
+void iommu_aux_detach_device(struct iommu_domain *domain, struct device *physdev)
 {
 	if (domain->ops->aux_detach_dev) {
-		domain->ops->aux_detach_dev(domain, dev);
-		trace_detach_device_from_domain(dev);
+		domain->ops->aux_detach_dev(domain, physdev, NULL);
+		trace_detach_device_from_domain(physdev);
 	}
 }
 EXPORT_SYMBOL_GPL(iommu_aux_detach_device);
 
-int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
+int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *physdev)
 {
 	int ret = -ENODEV;
 
 	if (domain->ops->aux_get_pasid)
-		ret = domain->ops->aux_get_pasid(domain, dev);
+		ret = domain->ops->aux_get_pasid(domain, physdev);
 
 	return ret;
 }
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 2ad26d8b4ab9..56297b4bbd0e 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -279,8 +279,10 @@ struct iommu_ops {
 	int (*dev_disable_feat)(struct device *dev, enum iommu_dev_features f);
 
 	/* Aux-domain specific attach/detach entries */
-	int (*aux_attach_dev)(struct iommu_domain *domain, struct device *dev);
-	void (*aux_detach_dev)(struct iommu_domain *domain, struct device *dev);
+	int (*aux_attach_dev)(struct iommu_domain *domain, struct device *physdev,
+			      struct device *subdev);
+	void (*aux_detach_dev)(struct iommu_domain *domain, struct device *physdev,
+			       struct device *subdev);
 	int (*aux_get_pasid)(struct iommu_domain *domain, struct device *dev);
 
 	struct iommu_sva *(*sva_bind)(struct device *dev, struct mm_struct *mm,
-- 
2.17.1

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