linux-kernel - Re: [PATCH 3/7] KVM: Move KVM_GET_NR_MMU

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Message-ID: <2c37f524-593f-a155-a01f-57a68b2e362c@redhat.com>
Date:   Fri, 3 Feb 2023 11:54:52 +0100
From:   Thomas Huth <thuth@...hat.com>
To:     Nicholas Piggin <npiggin@...il.com>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Marc Zyngier <maz@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        linux-kernel@...r.kernel.org,
        Oliver Upton <oliver.upton@...ux.dev>,
        Zenghui Yu <yuzenghui@...wei.com>,
        James Morse <james.morse@....com>,
        kvm-riscv@...ts.infradead.org, kvmarm@...ts.linux.dev,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 3/7] KVM: Move KVM_GET_NR_MMU_PAGES into the deprecation
 section

On 03/02/2023 11.16, Nicholas Piggin wrote:
> On Fri Feb 3, 2023 at 7:42 PM AEST, Thomas Huth wrote:
>> The KVM_GET_NR_MMU_PAGES ioctl is quite questionable on 64-bit hosts
>> since it fails to return the full 64 bits of the value that can be
>> set with the corresponding KVM_SET_NR_MMU_PAGES call. This ioctl
>> likely has also never really been used by userspace applications
>> (at least not by QEMU and kvmtool which I checked), so it's better
>> to move it to the deprecation section in kvm.h to make it clear for
>> developers that this also should not be used in new code in the
>> future anymore.
> 
> Did this get included in the series inadvertently?

No, it's here on purpose, as a second step to patch 2/7 (and a follow up 
from the discussion last year, see 
https://lore.kernel.org/kvm/YpZu6%2Fk+8EydfBKf@google.com/ ) ... sorry, I 
should have elaborated on this in the cover letter, too.

  Thomas