[PATCH V3 7/9] vfio: iommu driver notify callback

[Steve Sistare <steven.sistare@oracle.com>]

Define a vfio_iommu_driver_ops notify callback, for sending events to
the driver.  Drivers are not required to provide the callback, and
may ignore any events.  The handling of events is driver specific.

Define the CONTAINER_CLOSE event, called when the container's file
descriptor is closed.  This event signifies that no further state changes
will occur via container ioctl's.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 drivers/vfio/vfio.c  | 5 +++++
 include/linux/vfio.h | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 262ab0e..99458fc 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1220,6 +1220,11 @@ static int vfio_fops_open(struct inode *inode, struct file *filep)
 static int vfio_fops_release(struct inode *inode, struct file *filep)
 {
 	struct vfio_container *container = filep->private_data;
+	struct vfio_iommu_driver *driver = container->iommu_driver;
+
+	if (driver && driver->ops->notify)
+		driver->ops->notify(container->iommu_data,
+				    VFIO_DRIVER_NOTIFY_CONTAINER_CLOSE, NULL);
 
 	filep->private_data = NULL;
 
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 38d3c6a..9642579 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -57,6 +57,9 @@ extern int vfio_add_group_dev(struct device *dev,
 extern void vfio_device_put(struct vfio_device *device);
 extern void *vfio_device_data(struct vfio_device *device);
 
+/* events for the backend driver notify callback */
+#define VFIO_DRIVER_NOTIFY_CONTAINER_CLOSE	1
+
 /**
  * struct vfio_iommu_driver_ops - VFIO IOMMU driver callbacks
  */
@@ -90,6 +93,8 @@ struct vfio_iommu_driver_ops {
 					       struct notifier_block *nb);
 	int		(*dma_rw)(void *iommu_data, dma_addr_t user_iova,
 				  void *data, size_t count, bool write);
+	void		(*notify)(void *iommu_data, unsigned int event,
+				  void *data);
 };
 
 extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
-- 
1.8.3.1