> -----Original Message-----
> From: Cédric Le Goater <[email protected]>
> Sent: 02 September 2026 09:08
> To: Farhan Ali <[email protected]>; [email protected]; qemu-
> [email protected]
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; Shameer Kolothum Thodi
> <[email protected]>
> Subject: Re: [PATCH v4 2/4] vfio/pci: Add an error handler callback
> 
> External email: Use caution opening links or attachments
> 
> 
> +Shameer, who is looking at forwarding AER errors to guest :

Thanks Cédric.

I have sent out a kernel RFC series yesterday:
https://lore.kernel.org/all/[email protected]/

Please take a look. Probably this series can be extended later to come with a 
generic
AER error handling incorporating the new eventfd proposed in that RFC. I will
go through this one.

Thanks,
Shameer

> 
>    https://lore.kernel.org/qemu-
> devel/[email protected]
> amprd12.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 <[email protected]>
> > ---
> >   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);
> > +        error_report_err(err);
> > +    } else {
> > +        error_printf("Unrecoverable PCIe error detected for device %s",
> > +                     vdev->vbasedev.name);
> > +    }
> > +    error_printf("Please collect any data possible and then kill the
> > + guest");
> 
> how about that instead :
> 
>    if (err) {
>        error_report("Unrecoverable PCIe error detected for device %s: %s",
>                     vdev->vbasedev.name, error_get_pretty(err));
>        error_free(err);
>    } else {
>        error_report("Unrecoverable PCIe error detected for device %s",
>                     vdev->vbasedev.name);
>    }
>    error_printf("Please collect any data possible and then kill the guest\n");
> 
> >
> >       vm_stop(RUN_STATE_INTERNAL_ERROR);
> >   }
> > diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h index
> > c9ab949870..c067bbbebc 100644
> > --- a/hw/vfio/pci.h
> > +++ b/hw/vfio/pci.h
> > @@ -146,6 +146,7 @@ struct VFIOPCIDevice {
> >       EventNotifier err_notifier;
> >       EventNotifier req_notifier;
> >       int (*resetfn)(struct VFIOPCIDevice *);
> > +    bool (*err_handler)(struct VFIOPCIDevice *, Error **);
> 
> Please add documentation, something like :
> 
>    /*
>     * Platform-specific error recovery handler.
>     *
>     * Called when the host reports a PCI error via the VFIO error notifier.
>     * The handler should attempt to recover the device and forward the
>     * error to the guest if the platform supports it.
>     *
>     * @vdev: the VFIO PCI device that triggered the error
>     * @errp: set with the failure reason on false return
>     *
>     * Return true on success, the VM continues running.
>     * Return false on failure and set @errp, the VM will be stopped.
>     */
>    bool (*err_handler)(struct VFIOPCIDevice *vdev, Error **errp);
> 
> 
> That said, I'd prefer to see AER forwarding first.
> 
> Thanks,
> 
> C.
> 
> 
> >       uint32_t vendor_id;
> >       uint32_t device_id;
> >       uint32_t sub_vendor_id;

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