[RFC PATCH 02/18] KVM: Add KVM_CAP_USERFAULT and KVM_MEMORY_ATTRIBUTE_USERFAULT

[Anish Moorthy]

Not to nitpick an RFC, but since the stuff in this patch seems less
likely to change I think you should avoid using #ifdefs

For instance

On Wed, Jul 10, 2024 at 4:43 PM James Houghton <jthoughton at google.com> wrote:
> +static inline bool kvm_userfault_enabled(struct kvm *kvm)
> +{
> +#ifdef CONFIG_KVM_USERFAULT
> +       return !!rcu_access_pointer(kvm->userfault_ctx);
> +#else
> +       return false;
> +#endif
> +}

can be

> +static inline bool kvm_userfault_enabled(struct kvm *kvm)
> +{
> +    if (IS_ENABLED(CONFIG_KVM_USERFAULT)) {
> +       return !!rcu_access_pointer(kvm->userfault_ctx);
> +    } else {
> +       return false;
> +   }
> +}

(however kernel style tells you to write that :), the cap-supported
check can be moved into kvm_vm_ioctl_enable_userfault(), etc