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

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Date:   Fri, 03 Feb 2023 20:16:45 +1000
From:   "Nicholas Piggin" <npiggin@...il.com>
To:     "Thomas Huth" <thuth@...hat.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 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?

Thanks,
Nick

>
> Signed-off-by: Thomas Huth <thuth@...hat.com>
> ---
>  include/uapi/linux/kvm.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 55155e262646..f55965a4cec7 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -83,6 +83,8 @@ struct kvm_debug_guest {
>  
>  #define __KVM_DEPRECATED_VCPU_W_0x87 _IOW(KVMIO, 0x87, struct kvm_debug_guest)
>  
> +#define KVM_GET_NR_MMU_PAGES _IO(KVMIO, 0x45)
> +
>  /* *** End of deprecated interfaces *** */
>  
>  
> @@ -1442,7 +1444,6 @@ struct kvm_vfio_spapr_tce {
>  #define KVM_CREATE_VCPU           _IO(KVMIO,   0x41)
>  #define KVM_GET_DIRTY_LOG         _IOW(KVMIO,  0x42, struct kvm_dirty_log)
>  #define KVM_SET_NR_MMU_PAGES      _IO(KVMIO,   0x44)
> -#define KVM_GET_NR_MMU_PAGES      _IO(KVMIO,   0x45)
>  #define KVM_SET_USER_MEMORY_REGION _IOW(KVMIO, 0x46, \
>  					struct kvm_userspace_memory_region)
>  #define KVM_SET_TSS_ADDR          _IO(KVMIO,   0x47)
> -- 
> 2.31.1