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

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 1 Feb 2021 07:52:16 -0500
Steven Sistare <steven.sistare@oracle.com> wrote:

> On 2/1/2021 7:34 AM, Cornelia Huck wrote:
> > On Sat, 30 Jan 2021 11:51:41 -0500
> > Steven Sistare <steven.sistare@oracle.com> wrote:
> >   
> >> On 1/29/2021 4:57 PM, Alex Williamson wrote:  
> >>> On Fri, 29 Jan 2021 08:54:10 -0800
> >>> Steve Sistare <steven.sistare@oracle.com> wrote:
> >>>     
> >>>> 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/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.