Re: [PATCH v4 2/4] vfio/pci: Add an error handler callback

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

On 9/2/2026 3:39 AM, Markus Armbruster wrote:
> Cédric Le Goater <clg@redhat.com> writes:
>
>> +Shameer, who is looking at forwarding AER errors to guest :
>>
>>     https://lore.kernel.org/qemu-devel/SJ0PR12MB8614DDFEE3A9575564EDEF99ABFF2@SJ0PR12MB8614.namprd12.prod.outlook.com/
>>
>> On 8/31/26 20:31, Farhan Ali wrote:
>>> Provide a vfio error handling callback, that can be used by devices to
>>> handle PCI errors for passthrough devices.
>>>
>>> Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
>>> ---
>>>    hw/vfio/pci.c | 27 +++++++++++++++++++++------
>>>    hw/vfio/pci.h |  1 +
>>>    2 files changed, 22 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>>> index 428ab2f069..a2f489b34d 100644
>>> --- a/hw/vfio/pci.c
>>> +++ b/hw/vfio/pci.c
>>> @@ -3244,21 +3244,36 @@ void vfio_pci_put_device(VFIOPCIDevice *vdev)
>>>    static void vfio_err_notifier_handler(void *opaque)
>>>    {
>>>        VFIOPCIDevice *vdev = opaque;
>>> +    Error *err = NULL;
>>>    
>>>        if (!event_notifier_test_and_clear(&vdev->err_notifier)) {
>>>            return;
>>>        }
>>>    
>>>        /*
>>> -     * TBD. Retrieve the error details and decide what action
>>> -     * needs to be taken. One of the actions could be to pass
>>> -     * the error to the guest and have the guest driver recover
>>> -     * from the error. This requires that PCIe capabilities be
>>> -     * exposed to the guest. For now, we just terminate the
>>> +     * We can retrieve the error details and decide what action
>>> +     * needs to be taken in err_handler(). One of the actions could
>>> +     * be to pass the error to the guest and have the guest driver
>>> +     * recover from the error. This requires that PCIe capabilities be
>>> +     * exposed to the guest.
>>> +     *
>>> +     * If err_handler() is not implemented/fails, we just terminate the
>>>         * guest to contain the error.
>>>         */
>>>    
>>> -    error_report("%s(%s) Unrecoverable error detected. Please collect any data possible and then kill the guest", __func__, vdev->vbasedev.name);
>>> +    if (vdev->err_handler && vdev->err_handler(vdev, &err)) {
>>> +        return;
>>> +    }
>>> +
>>> +    if (err) {
>>> +        error_prepend(&err, "Unrecoverable PCIe error detected for device %s",
>>> +                      vdev->vbasedev.name);
> This requires use of ERRP_GUARD().  See "Why, when and how to use
> ERRP_GUARD()" in qapi/error.h.

okay, I can add the ERRP_GUARD(). AFAIU it will then look something like 
this?

Error **errp = NULL;
ERRP_GUARD();

if (vdev->err_handler && vdev->err_handler(vdev, errp)) {
	return;
}

if (*errp) {
	//print error with errp
} else {
	//generic error
}

Thanks

Farhan