From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sean Christopherson <seanjc@google.com>
Date: Mon, 13 Sep 2021 18:21:25 +0000
Subject: Re: [PATCH 2/2] kvm: rename KVM_MAX_VCPU_ID to KVM_MAX_VCPU_IDS
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To: Eduardo Habkost <ehabkost@redhat.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>

On Mon, Sep 13, 2021, Eduardo Habkost wrote:
> 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.

Heh, I haven't been able to come up with one, which is why I suggested the route
of making it an inclusive value internally within KVM.