Re: [PATCH 03/11] KVM: arm64: Add vm fd device attribute accessors

[Suzuki K Poulose <suzuki.poulose@xxxxxxx>]

On 20/03/2023 22:09, Oliver Upton wrote:
> A subsequent change will allow userspace to convey a filter for
> hypercalls through a vm device attribute. Add the requisite boilerplate
> for vm attribute accessors.
>
> Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
> ---
>   arch/arm64/kvm/arm.c | 29 +++++++++++++++++++++++++++++
>   1 file changed, 29 insertions(+)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 3bd732eaf087..b6e26c0e65e5 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -1439,11 +1439,28 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
>   	}
>   }
>   
> +static int kvm_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
> +{
> +	switch (attr->group) {
> +	default:
> +		return -ENXIO;
> +	}
> +}
> +
> +static int kvm_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
> +{
> +	switch (attr->group) {
> +	default:
> +		return -ENXIO;
> +	}
> +}
> +
>   long kvm_arch_vm_ioctl(struct file *filp,
>   		       unsigned int ioctl, unsigned long arg)
>   {
>   	struct kvm *kvm = filp->private_data;
>   	void __user *argp = (void __user *)arg;
> +	struct kvm_device_attr attr;
>   
>   	switch (ioctl) {
>   	case KVM_CREATE_IRQCHIP: {
> @@ -1479,6 +1496,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
>   			return -EFAULT;
>   		return kvm_vm_ioctl_mte_copy_tags(kvm, &copy_tags);
>   	}
> +	case KVM_HAS_DEVICE_ATTR: {
> +		if (copy_from_user(&attr, argp, sizeof(attr)))
> +			return -EFAULT;
> +
> +		return kvm_vm_has_attr(kvm, &attr);
> +	}
> +	case KVM_SET_DEVICE_ATTR: {
> +		if (copy_from_user(&attr, argp, sizeof(attr)))
> +			return -EFAULT;
> +
> +		return kvm_vm_set_attr(kvm, &attr);
> +	}

Is there a reason to exclude KVM_GET_DEVICE_ATTR handling ?

Suzuki