[PATCH v8 04/10] iommufd: Add iommufd_ctx_has_group()

[Yi Liu <yi.l.liu@xxxxxxxxx>]

This adds the helper to check if any device within the given iommu_group
has been bound with the iommufd_ctx. This is helpful for the checking on
device ownership for the devices which have not been bound but cannot be
bound to any other iommufd_ctx as the iommu_group has been bound.

Tested-by: Terrence Xu <terrence.xu@xxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/iommu/iommufd/device.c | 30 ++++++++++++++++++++++++++++++
 include/linux/iommufd.h        |  2 ++
 2 files changed, 32 insertions(+)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 4f9b2142274c..4571344c8508 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -98,6 +98,36 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_device_bind, IOMMUFD);
 
+/**
+ * iommufd_ctx_has_group - True if any device within the group is bound
+ *                         to the ictx
+ * @ictx: iommufd file descriptor
+ * @group: Pointer to a physical iommu_group struct
+ *
+ * True if any device within the group has been bound to this ictx, ex. via
+ * iommufd_device_bind(), therefore implying ictx ownership of the group.
+ */
+bool iommufd_ctx_has_group(struct iommufd_ctx *ictx, struct iommu_group *group)
+{
+	struct iommufd_object *obj;
+	unsigned long index;
+
+	if (!ictx || !group)
+		return false;
+
+	xa_lock(&ictx->objects);
+	xa_for_each(&ictx->objects, index, obj) {
+		if (obj->type == IOMMUFD_OBJ_DEVICE &&
+		    container_of(obj, struct iommufd_device, obj)->group == group) {
+			xa_unlock(&ictx->objects);
+			return true;
+		}
+	}
+	xa_unlock(&ictx->objects);
+	return false;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_ctx_has_group, IOMMUFD);
+
 /**
  * iommufd_device_unbind - Undo iommufd_device_bind()
  * @idev: Device returned by iommufd_device_bind()
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 1129a36a74c4..f241bafa03da 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -16,6 +16,7 @@ struct page;
 struct iommufd_ctx;
 struct iommufd_access;
 struct file;
+struct iommu_group;
 
 struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
 					   struct device *dev, u32 *id);
@@ -50,6 +51,7 @@ void iommufd_ctx_get(struct iommufd_ctx *ictx);
 #if IS_ENABLED(CONFIG_IOMMUFD)
 struct iommufd_ctx *iommufd_ctx_from_file(struct file *file);
 void iommufd_ctx_put(struct iommufd_ctx *ictx);
+bool iommufd_ctx_has_group(struct iommufd_ctx *ictx, struct iommu_group *group);
 
 int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova,
 			     unsigned long length, struct page **out_pages,
-- 
2.34.1