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Date:   Tue, 13 Jun 2023 14:16:16 -0700
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Subject: Re: [PATCH RESEND v2] KVM: move KVM_CAP_DEVICE_CTRL to the generic check
From:   Sean Christopherson <seanjc@google.com>
To:     Wei Wang <wei.w.wang@intel.com>
Cc:     pbonzini@redhat.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Anup Patel <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org,
        linux-riscv@lists.infradead.org
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+<everyone else>

Please use scripts/get_maintainer.pl to generate the To/Cc lists.  This may be
trivial, but it still needs eyeballs from the relevant maintainers.

On Wed, Mar 15, 2023, Wei Wang wrote:
> KVM_CAP_DEVICE_CTRL allows userspace to check if the kvm_device
> framework (e.g. KVM_CREATE_DEVICE) is supported by KVM. Move
> KVM_CAP_DEVICE_CTRL to the generic check for the two reasons:
> 1) it already supports arch agnostic usages (i.e. KVM_DEV_TYPE_VFIO).
> For example, userspace VFIO implementation may needs to create
> KVM_DEV_TYPE_VFIO on x86, riscv, or arm etc. It is simpler to have it
> checked at the generic code than at each arch's code.
> 2) KVM_CREATE_DEVICE has been added to the generic code.
> 
> Link: https://lore.kernel.org/all/20221215115207.14784-1-wei.w.wang@intel.com
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/arm64/kvm/arm.c       | 1 -
>  arch/powerpc/kvm/powerpc.c | 1 -
>  arch/riscv/kvm/vm.c        | 1 -
>  arch/s390/kvm/kvm-s390.c   | 1 -
>  virt/kvm/kvm_main.c        | 1 +
>  5 files changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 3bd732eaf087..96329e675771 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -202,7 +202,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		r = vgic_present;
>  		break;
>  	case KVM_CAP_IOEVENTFD:
> -	case KVM_CAP_DEVICE_CTRL:
>  	case KVM_CAP_USER_MEMORY:
>  	case KVM_CAP_SYNC_MMU:
>  	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 4c5405fc5538..185efed23896 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -526,7 +526,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ENABLE_CAP:
>  	case KVM_CAP_ONE_REG:
>  	case KVM_CAP_IOEVENTFD:
> -	case KVM_CAP_DEVICE_CTRL:
>  	case KVM_CAP_IMMEDIATE_EXIT:
>  	case KVM_CAP_SET_GUEST_DEBUG:
>  		r = 1;
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> index 65a964d7e70d..6efe93b282e1 100644
> --- a/arch/riscv/kvm/vm.c
> +++ b/arch/riscv/kvm/vm.c
> @@ -57,7 +57,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  
>  	switch (ext) {
>  	case KVM_CAP_IOEVENTFD:
> -	case KVM_CAP_DEVICE_CTRL:
>  	case KVM_CAP_USER_MEMORY:
>  	case KVM_CAP_SYNC_MMU:
>  	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 39b36562c043..7b097b5253ca 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -556,7 +556,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ENABLE_CAP:
>  	case KVM_CAP_S390_CSS_SUPPORT:
>  	case KVM_CAP_IOEVENTFD:
> -	case KVM_CAP_DEVICE_CTRL:
>  	case KVM_CAP_S390_IRQCHIP:
>  	case KVM_CAP_VM_ATTRIBUTES:
>  	case KVM_CAP_MP_STATE:
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index d255964ec331..71cc63640173 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4523,6 +4523,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>  #endif
>  	case KVM_CAP_BINARY_STATS_FD:
>  	case KVM_CAP_SYSTEM_EVENT_DATA:
> +	case KVM_CAP_DEVICE_CTRL:
>  		return 1;
>  	default:
>  		break;
> -- 
> 2.27.0
>