linux-kernel - Re: [PATCH 0/5] KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX

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Date:   Thu, 11 Nov 2021 17:32:00 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Eduardo Habkost <ehabkost@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        Andrew Jones <drjones@...hat.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Anup Patel <anup.patel@....com>,
        Paul Mackerras <paulus@...abs.org>,
        Michael Ellerman <mpe@...erman.id.au>, kvm-ppc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        kvm-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ibm.com>
Subject: Re: [PATCH 0/5] KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS and
 re-purpose it on x86

On 11/11/21 17:27, Vitaly Kuznetsov wrote:
> This is a comtinuation of "KVM: x86: Drop arbitraty KVM_SOFT_MAX_VCPUS"
> (https://lore.kernel.org/kvm/20211111134733.86601-1-vkuznets@redhat.com/)
> work.
> 
> 1) Enforce KVM_CAP_NR_VCPUS <= KVM_CAP_MAX_VCPUS rule on all
>   architectures. [Sean Christopherson]
> 2) Make KVM_CAP_NR_VCPUS return num_online_cpus() and not an arbitrary
>   value of '710' on x86.
> 
> Everything but x86 was only 'eyeball tested', the change is trivial
> but sorry in advance if I screwed up)

Christian, can you look at this for s390?  Returning a fixed value seems 
wrong for KVM_CAP_NR_VCPUS.

Thanks,

Paolo

> Vitaly Kuznetsov (5):
>    KVM: arm64: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS
>    KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS
>    KVM: PPC: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS
>    KVM: RISC-V: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS
>    KVM: x86: Drop arbitraty KVM_SOFT_MAX_VCPUS
> 
>   arch/arm64/kvm/arm.c            | 7 ++++++-
>   arch/mips/kvm/mips.c            | 2 +-
>   arch/powerpc/kvm/powerpc.c      | 4 ++--
>   arch/riscv/kvm/vm.c             | 2 +-
>   arch/x86/include/asm/kvm_host.h | 1 -
>   arch/x86/kvm/x86.c              | 2 +-
>   6 files changed, 11 insertions(+), 7 deletions(-)
>