Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210913135745.13944-1-jgross@suse.com> <20210913135745.13944-3-jgross@suse.com>
 <YT97K7yXyCrphyCt@google.com>
In-Reply-To: <YT97K7yXyCrphyCt@google.com>
From:   Eduardo Habkost <ehabkost@redhat.com>
Date:   Mon, 13 Sep 2021 12:56:41 -0400
Message-ID: <CAOpTY_pyeOo2Kh-r1cEFk2XL4g8A1mxQpP1y62thWk2mh6XUUg@mail.gmail.com>
Subject: Re: [PATCH 2/2] kvm: rename KVM_MAX_VCPU_ID to KVM_MAX_VCPU_IDS
To:     Sean Christopherson <seanjc@google.com>
Cc:     Juergen Gross <jgross@suse.com>, kvm@vger.kernel.org,
        x86@kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
        kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-kselftest@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Huacai Chen <chenhuacai@kernel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Paul Mackerras <paulus@ozlabs.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Shuah Khan <shuah@kernel.org>,
        Shuah Khan <skhan@linuxfoundation.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Sep 13, 2021 at 12:24 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Mon, Sep 13, 2021, Juergen Gross wrote:
> > KVM_MAX_VCPU_ID is not specifying the highest allowed vcpu-id, but the
> > number of allowed vcpu-ids. This has already led to confusion, so
> > rename KVM_MAX_VCPU_ID to KVM_MAX_VCPU_IDS to make its semantics more
> > clear
>
> My hesitation with this rename is that the max _number_ of IDs is not the same
> thing as the max allowed ID.  E.g. on x86, given a capability that enumerates the
> max number of IDs, I would expect to be able to create vCPUs with arbitrary 32-bit
> x2APIC IDs so long as the total number of IDs is below the max.
>

What name would you suggest instead? KVM_VCPU_ID_LIMIT, maybe?

I'm assuming we are not going to redefine KVM_MAX_VCPU_ID to be an
inclusive limit.

--
Eduardo