Re: [PATCH v5 2/2] KVM: Make KVM_CAP_IRQFD dependent on KVM_CAP_IRQCHIP

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Mon, 30 Nov 2015 12:40:45 +0300
Pavel Fedin <p.fedin@samsung.com> wrote:

> Now at least ARM is able to determine whether the machine has
> virtualization support for irqchip or not at runtime. Obviously,
> irqfd requires irqchip.
> 
> Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
> ---
>  virt/kvm/kvm_main.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 7873d6d..a057d5e 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2716,13 +2716,15 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>  	case KVM_CAP_INTERNAL_ERROR_DATA:
>  #ifdef CONFIG_HAVE_KVM_MSI
>  	case KVM_CAP_SIGNAL_MSI:
> +		/* Fallthrough */
>  #endif
> +	case KVM_CAP_CHECK_EXTENSION_VM:
> +		return 1;
>  #ifdef CONFIG_HAVE_KVM_IRQFD
>  	case KVM_CAP_IRQFD:
>  	case KVM_CAP_IRQFD_RESAMPLE:
> +		return kvm_vm_ioctl_check_extension(kvm, KVM_CAP_IRQCHIP);

This won't work for s390, as it doesn't have KVM_CAP_IRQCHIP but
KVM_CAP_S390_IRQCHIP (which needs to be enabled).

>  #endif
> -	case KVM_CAP_CHECK_EXTENSION_VM:
> -		return 1;
>  #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
>  	case KVM_CAP_IRQ_ROUTING:
>  		return KVM_MAX_IRQ_ROUTES;