[PATCH 06/11] iommu: Expose group variants of dma ownership interfaces

[Lu Baolu]

The vfio needs to set DMA_OWNER_USER for the entire group when attaching
it to a vfio container. So expose group variants of setting/releasing dma
ownership for this purpose.

This also exposes the helper iommu_group_dma_owner_unclaimed() for vfio
report to userspace if the group is viable to user assignment, for
compatibility with VFIO_GROUP_FLAGS_VIABLE.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 include/linux/iommu.h | 21 ++++++++++++++++
 drivers/iommu/iommu.c | 57 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index f77eb9e7788a..3d2dfd220d3c 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -696,6 +696,10 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle);
 int iommu_device_set_dma_owner(struct device *dev, enum iommu_dma_owner owner,
 			       struct file *user_file);
 void iommu_device_release_dma_owner(struct device *dev, enum iommu_dma_owner owner);
+int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
+			      struct file *user_file);
+void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner);
+bool iommu_group_dma_owner_unclaimed(struct iommu_group *group);
 
 #else /* CONFIG_IOMMU_API */
 
@@ -1112,6 +1116,23 @@ static inline void iommu_device_release_dma_owner(struct device *dev,
 						  enum iommu_dma_owner owner)
 {
 }
+
+static inline int iommu_group_set_dma_owner(struct iommu_group *group,
+					    enum iommu_dma_owner owner,
+					    struct file *user_file)
+{
+	return -EINVAL;
+}
+
+static inline void iommu_group_release_dma_owner(struct iommu_group *group,
+						 enum iommu_dma_owner owner)
+{
+}
+
+static inline bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
+{
+	return false;
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 916a4d448150..3dcd3fc4290a 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3431,6 +3431,63 @@ static void __iommu_group_release_dma_owner(struct iommu_group *group,
 	}
 }
 
+/**
+ * iommu_group_set_dma_owner() - Set DMA ownership of a group
+ * @group: The group.
+ * @owner: DMA_OWNER_KERNEL or DMA_OWNER_USER.
+ * @user_file: The device fd when set USER ownership.
+ *
+ * This is to support backward compatibility for legacy vfio which manages
+ * dma ownership in group level. New invocations on this interface should be
+ * prohibited. Instead, please turn to iommu_device_set_dma_owner().
+ */
+int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
+			      struct file *user_file)
+{
+	int ret;
+
+	mutex_lock(&group->mutex);
+	ret = __iommu_group_set_dma_owner(group, owner, user_file);
+	mutex_unlock(&group->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_group_set_dma_owner);
+
+/**
+ * iommu_group_release_dma_owner() - Release DMA ownership of a group
+ * @group: The group.
+ * @owner: DMA_OWNER_KERNEL or DMA_OWNER_USER.
+ *
+ * Release the DMA ownership claimed by iommu_group_set_dma_owner().
+ */
+void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner)
+{
+	mutex_lock(&group->mutex);
+	__iommu_group_release_dma_owner(group, owner);
+	mutex_unlock(&group->mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);
+
+/**
+ * iommu_group_dma_owner_unclaimed() - Is group dma ownership claimed
+ * @group: The group.
+ *
+ * This provides status check on a given group. It is racey and only for
+ * non-binding status reporting.
+ */
+bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
+{
+	enum iommu_dma_owner owner;
+
+	mutex_lock(&group->mutex);
+	owner = group->dma_owner;
+	mutex_unlock(&group->mutex);
+
+	return owner == DMA_OWNER_NONE;
+}
+EXPORT_SYMBOL_GPL(iommu_group_dma_owner_unclaimed);
+
 /**
  * iommu_device_set_dma_owner() - Set DMA ownership of a device
  * @dev: The device.
-- 
2.25.1