Re: [PATCH 16/32] KVM: s390: expose the guest zPCI interpretation facility

[Christian Borntraeger]

Am 07.12.21 um 21:57 schrieb Matthew Rosato:
> This facility will be used to enable interpretive execution of zPCI
> instructions.
>
> Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
> ---
>   arch/s390/kvm/kvm-s390.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index c8fe9b7c2395..09991d05c871 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2751,6 +2751,10 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>   		set_kvm_facility(kvm->arch.model.fac_mask, 147);
>   		set_kvm_facility(kvm->arch.model.fac_list, 147);
>   	}
> +	if (sclp.has_zpci_interp && test_facility(69)) {
> +		set_kvm_facility(kvm->arch.model.fac_mask, 69);
> +		set_kvm_facility(kvm->arch.model.fac_list, 69);
> +	}


Do we need the setting of these stfle bits somewhere? I think QEMU sets them as well for the guest.
We only need this when the kernel probes for this (test_kvm_facility) But then the question is, shouldnt
we then simply check for sclp bits in those places?
See also patch 19. We need to build it in a way that allows VSIE support later on.

>   
>   	if (css_general_characteristics.aiv && test_facility(65))
>   		set_kvm_facility(kvm->arch.model.fac_mask, 65);