linux-kernel - Re: [PATCH v4 1/1] s390x: KVM: accept STSI for CPU topology information

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Date:   Thu, 16 Sep 2021 16:03:43 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Pierre Morel <pmorel@...ux.ibm.com>, kvm@...r.kernel.org
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        borntraeger@...ibm.com, frankja@...ux.ibm.com, cohuck@...hat.com,
        thuth@...hat.com, imbrenda@...ux.ibm.com, hca@...ux.ibm.com,
        gor@...ux.ibm.com
Subject: Re: [PATCH v4 1/1] s390x: KVM: accept STSI for CPU topology
 information

>   struct kvm_vm_stat {
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 51d1594bd6cd..f3887e13c5db 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -608,6 +608,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>   	case KVM_CAP_S390_PROTECTED:
>   		r = is_prot_virt_host();
>   		break;
> +	case KVM_CAP_S390_CPU_TOPOLOGY:
> +		r = test_facility(11);
> +		break;
>   	default:
>   		r = 0;
>   	}
> @@ -819,6 +822,19 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
>   		icpt_operexc_on_all_vcpus(kvm);
>   		r = 0;
>   		break;
> +	case KVM_CAP_S390_CPU_TOPOLOGY:

As given in my example, this should be

r = -EINVAL;
mutex_lock(&kvm->lock);
if (kvm->created_vcpus) {
	r = -EBUSY;
} else if (test_facility(11)) {
...
}

Similar to how we handle KVM_CAP_S390_VECTOR_REGISTERS.

[...]

> +
> +	/* PTF needs both host and guest facilities to enable interpretation */
> +	if (test_kvm_facility(vcpu->kvm, 11) && test_facility(11))
> +		vcpu->arch.sie_block->ecb |= ECB_PTF;

This should be simplified to

if (test_kvm_facility(vcpu->kvm, 11))

then. (vsie code below is correct)


-- 
Thanks,

David / dhildenb