Message-ID: <d7547cab-88d6-18a9-8307-bf2cc5d61163@de.ibm.com>
Date:   Tue, 16 Nov 2021 09:15:43 +0100
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Subject: Re: [PATCH 0/5] KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS and
 re-purpose it on x86
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To:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org
Cc:     Sean Christopherson <seanjc@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Eduardo Habkost <ehabkost@redhat.com>,
        Marc Zyngier <maz@kernel.org>,
        Andrew Jones <drjones@redhat.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
        Anup Patel <anup.patel@wdc.com>,
        Paul Mackerras <paulus@ozlabs.org>,
        Michael Ellerman <mpe@ellerman.id.au>, kvm-ppc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
        kvm-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        Janosch Frank <frankja@linux.ibm.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>
References: <20211111162746.100598-1-vkuznets@redhat.com>
 <4a3c7be7-12fa-6e47-64eb-02e6c5be5dbc@redhat.com>
 <ecd55383-7089-b3cd-30cc-3f9feb7eadb4@de.ibm.com> <877dd9pfri.fsf@redhat.com>
From:   Christian Borntraeger <borntraeger@de.ibm.com>
In-Reply-To: <877dd9pfri.fsf@redhat.com>
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Am 15.11.21 um 17:04 schrieb Vitaly Kuznetsov:
[...]
> or cap KVM_CAP_MAX_VCPUS value with num_online_cpus(), e.g.
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 6a6dd5e1daf6..1cfe36f6432e 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -585,6 +585,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>                          r = KVM_MAX_VCPUS;
>                  else if (sclp.has_esca && sclp.has_64bscao)
>                          r = KVM_S390_ESCA_CPU_SLOTS;
> +               if (ext == KVM_CAP_NR_VCPUS)
> +                       r = min_t(unsigned int, num_online_cpus(), r);
>                  break;
>          case KVM_CAP_S390_COW:
>                  r = MACHINE_HAS_ESOP;

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>


I think this is the better variant. Thanks.