Re: [PATCH] s390x/pci: set kvm_msi_via_irqfd_allowed

[David Hildenbrand <david@redhat.com>]

On 01.10.25 22:05, Matthew Rosato wrote:
> Allow irqfd to be used for virtio-pci on s390x if the kernel supports
> it.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>   hw/s390x/s390-pci-bus.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
> index e8e41c8a9a..88852acf45 100644
> --- a/hw/s390x/s390-pci-bus.c
> +++ b/hw/s390x/s390-pci-bus.c
> @@ -900,6 +900,7 @@ static void s390_pcihost_realize(DeviceState *dev, Error **errp)
>       s390_pci_init_default_group();
>       css_register_io_adapters(CSS_IO_ADAPTER_PCI, true, false,
>                                S390_ADAPTER_SUPPRESSIBLE, errp);
> +    kvm_msi_via_irqfd_allowed = kvm_irqfds_enabled();

Just wondering, what's the net result of this patch?

I assume better performance. Might be worth adding that "why" to the 
patch description.

-- 
Cheers

David / dhildenb