Re: [PATCH] vfio/pci: Don't remove irqchip notifier if not registered

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 31 Dec 2019 08:39:15 -0500
Peter Xu <peterx@redhat.com> wrote:

> The kvm irqchip notifier is only registered if the device supports
> INTx, however it's unconditionally removed.  If the assigned device
> does not support INTx, this will cause QEMU to crash when unplugging
> the device from the system.  Change it to conditionally remove the
> notifier only if the notify hook is setup.
> 
> CC: Eduardo Habkost <ehabkost@redhat.com>
> CC: David Gibson <david@gibson.dropbear.id.au>
> CC: Alex Williamson <alex.williamson@redhat.com>
> Reported-by: yanghliu@redhat.com
> Fixes: c5478fea27 ("vfio/pci: Respond to KVM irqchip change notifier", 2019-11-26)
> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1782678
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  hw/vfio/pci.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 2d40b396f2..337a173ce7 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3076,7 +3076,9 @@ static void vfio_exitfn(PCIDevice *pdev)
>      vfio_unregister_req_notifier(vdev);
>      vfio_unregister_err_notifier(vdev);
>      pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
> -    kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
> +    if (vdev->irqchip_change_notifier.notify) {
> +        kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
> +    }
>      vfio_disable_interrupts(vdev);
>      if (vdev->intx.mmap_timer) {
>          timer_free(vdev->intx.mmap_timer);


Thanks, Peter!  Sent a pull request with David and Greg's R-b, stable
tag, and debug credit to Eduardo as I think he spotted the issue first.
Thanks,

Alex