Re: [PATCH v18 3/4] vfio/pci: Add a reset_done callback for vfio-pci driver

[Farhan Ali <alifm@linux.ibm.com>]

On 6/4/2026 1:28 AM, Keith Busch wrote:
> On Wed, Jun 03, 2026 at 11:24:14AM -0700, Farhan Ali wrote:
>> +static void vfio_pci_core_aer_reset_done(struct pci_dev *pdev)
>> +{
>> +	struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
>> +
>> +	if (!vdev->pci_saved_state)
>> +		return;
>> +
>> +	pci_load_saved_state(pdev, vdev->pci_saved_state);
>> +	pci_restore_state(pdev);
>> +}
> Shouldn't there be a cooresponding user space notification that the
> device has been restored? There's an eventfd on the error detected side
> so user space can know the device needs recovery, but how does it come
> to know that the reset is completed?

I think if the VFIO_DEVICE_RESET ioctl completes successfully it should 
be an indication that the reset has completed? AFAIU the ioctl will 
drive a reset via pci_try_reset_function(). If reset completes completes 
successfully the reset_done() callback is called via pci_dev_restore(). 
So I don't think we need an eventfd to notify on reset completion. 
Otherwise we would have the same problem today, where userspace is 
unaware that VFIO_DEVICE_RESET did indeed successfully reset the device, 
no? Or am I missing something?

Thanks

Farhan