Re: [Qemu-trivial] [PATCH] hw/vfio: improve error message when cannot init vfio event notifiers

[Michael Tokarev]

10.10.2017 13:22, Jim Quigley wrote:
> More information is required to assist trouble-shooting when
> QEMU fails to initialise the event notifications for devices
> assigned with VFIO-PCI. Instead of supplying the user with a cryptic
> error number only, print out a proper error message with strerror()
> so that the user has a better way to figure out what the problem is.
> 
> Reviewed-by: Liam Merwick <address@hidden>
> Signed-off-by: Jim Quigley <address@hidden>
> ---
> Cc: address@hidden
> Cc: address@hidden
> Cc: address@hidden
> Cc: address@hidden
> ---
>  hw/vfio/pci.c | 35 ++++++++++++++++++++++++-----------
>  1 file changed, 24 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 31e1edf..3bffb93 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -430,13 +430,16 @@ static int vfio_enable_vectors(VFIOPCIDevice *vdev, 
> bool msix)
>  static void vfio_add_kvm_msi_virq(VFIOPCIDevice *vdev, VFIOMSIVector *vector,
>                                    int vector_n, bool msix)
>  {
> -    int virq;
> +    int virq, ret;
>  
>      if ((msix && vdev->no_kvm_msix) || (!msix && vdev->no_kvm_msi)) {
>          return;
>      }
>  
> -    if (event_notifier_init(&vector->kvm_interrupt, 0)) {
> +    ret = event_notifier_init(&vector->kvm_interrupt, 0);
> +    if (ret) {
> +        error_report("vfio (%s): Error: unable to init event notifier: %s 
> (%d)",
> +                     __func__, strerror(-ret), -ret);

Since this pattern gets repeated again and again, maybe we can either
use a common wrapper or move that eror reporting into event_notifier_init()?
Note there are other users of this function, besides hw/vfio, and maybe
these, too, can benefit from better error reporting?

Thanks,

/mjt