Re: [PATCH v4 4/6] KVM/vfio: Use file-based reference counting for KVM

[Alex Williamson]

On Mon, 28 Sep 2026 15:07:05 +0200
Steffen Eiden <seiden@xxxxxxxxxxxxx> wrote:
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 423ead48aafe..ed96acfa8635 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -472,36 +472,14 @@ void vfio_unregister_group_dev(struct vfio_device *device)
>  EXPORT_SYMBOL_GPL(vfio_unregister_group_dev);
>  
>  #if IS_ENABLED(CONFIG_KVM)
> -void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm)
> +void vfio_device_get_kvm_safe(struct vfio_device *device, struct file *kvm)
>  {
> -	void (*pfn)(struct kvm *kvm);
> -	bool (*fn)(struct kvm *kvm);
> -	bool ret;
> -
>  	lockdep_assert_held(&device->dev_set->lock);
>  
>  	if (!kvm)
>  		return;
>  
> -	pfn = symbol_get(kvm_put_kvm);
> -	if (WARN_ON(!pfn))
> -		return;
> -
> -	fn = symbol_get(kvm_get_kvm_safe);
> -	if (WARN_ON(!fn)) {
> -		symbol_put(kvm_put_kvm);
> -		return;
> -	}
> -
> -	ret = fn(kvm);
> -	symbol_put(kvm_get_kvm_safe);
> -	if (!ret) {
> -		symbol_put(kvm_put_kvm);
> -		return;
> -	}
> -
> -	device->put_kvm = pfn;
> -	device->kvm = kvm;
> +	device->kvm = get_file(kvm);
>  }

Nit, retaining the "_safe" naming here and through the callers is now
meaningless and could be dropped.  Otherwise,

Acked-by: Alex Williamson <alex@xxxxxxxxxxx>

Thanks,
Alex