On 02/02/17 16:32, Andre Przywara wrote:
> If we need to inject an MSI into the guest, we rely at the moment on a
> working GSI MSI routing functionality. However we can get away without
> IRQ routing, if the host supports MSI injection via the KVM_SIGNAL_MSI
> ioctl.
> So we try the GSI routing first, but if that fails due to a missing
> IRQ routing functionality, we fall back to KVM_SIGNAL_MSI (if that is
> supported).
> 
> Signed-off-by: Andre Przywara <andre.przyw...@arm.com>
> ---
>  virtio/pci.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/virtio/pci.c b/virtio/pci.c
> index 7cc0ba4..98bf6b7 100644
> --- a/virtio/pci.c
> +++ b/virtio/pci.c
> @@ -193,8 +193,14 @@ static bool virtio_pci__specific_io_out(struct kvm *kvm, 
> struct virtio_device *v
>  
>                       gsi = irq__add_msix_route(kvm,
>                                                 &vpci->msix_table[vec].msg);
> -                     if (gsi >= 0)
> +                     if (gsi >= 0) {
>                               vpci->config_gsi = gsi;
> +                             break;
> +                     }
> +                     if (gsi == -ENXIO &&
> +                         vpci->features & VIRTIO_PCI_F_SIGNAL_MSI)
> +                                     break;
> +                     die("failed to configure MSIs");
>                       break;
>               case VIRTIO_MSI_QUEUE_VECTOR:
>                       vec = ioport__read16(data);
> @@ -205,8 +211,14 @@ static bool virtio_pci__specific_io_out(struct kvm *kvm, 
> struct virtio_device *v
>  
>                       gsi = irq__add_msix_route(kvm,
>                                                 &vpci->msix_table[vec].msg);
> -                     if (gsi < 0)
> +                     if (gsi < 0) {
> +                             if (gsi == -ENXIO &&
> +                                 vpci->features & VIRTIO_PCI_F_SIGNAL_MSI)
> +                                     break;
> +
> +                             die("failed to configure MSIs");
>                               break;
> +                     }
>                       vpci->gsis[vpci->queue_selector] = gsi;

Is it really expected to find -ENXIO in this array instead of a GSI?

>                       if (vdev->ops->notify_vq_gsi)
>                               vdev->ops->notify_vq_gsi(kvm, vpci->dev,
> 

Thanks,

        M.
-- 
Jazz is not dead. It just smells funny...
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