On Mon, 1 Feb 2021 07:52:16 -0500
Steven Sistare [off-list ref] wrote:

On 2/1/2021 7:34 AM, Cornelia Huck wrote:

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On Sat, 30 Jan 2021 11:51:41 -0500
Steven Sistare [off-list ref] wrote:
  

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On 1/29/2021 4:57 PM, Alex Williamson wrote:  

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On Fri, 29 Jan 2021 08:54:10 -0800
Steve Sistare [off-list ref] wrote:
    

quoted

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 <redacted>
---
 drivers/vfio/vfio.c  | 5 +++++
 include/linux/vfio.h | 5 +++++
 2 files changed, 10 insertions(+)

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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    

We should use an enum for type checking.    

Agreed.
I see you changed the value to 0.  Do you want to reserve 0 for invalid-event?
(I know, this is internal and can be changed).  Your call.  

I'm not sure what we would use an invalid-event event for... the type
checking provided by the enum should be enough?  

I should have described it as no-event or null-event.  It can be useful when
initializing a struct member that stores an event, eg, last-event-received.

I think we could just use -1 for that. Anyway, easy to change if a need
comes up.