Re: [PATCH v4 1/5] vfio/pci: Fix a segfault in vfio_realize

[Joao Martins]

On 29/06/2023 09:40, Zhenzhong Duan wrote:
> The kvm irqchip notifier is only registered if the device supports
> INTx, however it's unconditionally removed in vfio realize error
> path. If the assigned device does not support INTx, this will cause
> QEMU to crash when vfio realize fails. Change it to conditionally
> remove the notifier only if the notify hook is setup.
> 
> Before fix:
> (qemu) device_add vfio-pci,host=81:11.1,id=vfio1,bus=root1,xres=1
> Connection closed by foreign host.
> 
> After fix:
> (qemu) device_add vfio-pci,host=81:11.1,id=vfio1,bus=root1,xres=1
> Error: vfio 0000:81:11.1: xres and yres properties require display=on
> (qemu)
> 
> Fixes: c5478fea27ac ("vfio/pci: Respond to KVM irqchip change notifier")
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

Reviewed-by: Joao Martins <joao.m.martins@oracle.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 73e19a04b2bf..48df517f79ee 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3221,7 +3221,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>  
>  out_deregister:
>      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);
> +    }
>  out_teardown:
>      vfio_teardown_msi(vdev);
>      vfio_bars_exit(vdev);