[PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator

[Alex Williamson]

On Thu, 29 Jan 2026 21:24:51 +0000
David Matlack <dmatlack at google.com> wrote:
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 0c771064c0b8..19e88322af2c 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -258,6 +258,10 @@ static int __init vfio_pci_init(void)
>  	int ret;
>  	bool is_disable_vga = true;
>  
> +	ret = vfio_pci_liveupdate_init();
> +	if (ret)
> +		return ret;
> +
>  #ifdef CONFIG_VFIO_PCI_VGA
>  	is_disable_vga = disable_vga;
>  #endif
> @@ -266,8 +270,10 @@ static int __init vfio_pci_init(void)
>  
>  	/* Register and scan for devices */
>  	ret = pci_register_driver(&vfio_pci_driver);
> -	if (ret)
> +	if (ret) {
> +		vfio_pci_liveupdate_cleanup();
>  		return ret;
> +	}
>  
>  	vfio_pci_fill_ids();
>  
> @@ -281,6 +287,7 @@ module_init(vfio_pci_init);
>  static void __exit vfio_pci_cleanup(void)
>  {
>  	pci_unregister_driver(&vfio_pci_driver);
> +	vfio_pci_liveupdate_cleanup();
>  }
>  module_exit(vfio_pci_cleanup);
>  
> diff --git a/drivers/vfio/pci/vfio_pci_liveupdate.c b/drivers/vfio/pci/vfio_pci_liveupdate.c
> new file mode 100644
> index 000000000000..b84e63c0357b
> --- /dev/null
> +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c
> @@ -0,0 +1,69 @@
...
> +static const struct liveupdate_file_ops vfio_pci_liveupdate_file_ops = {
> +	.can_preserve = vfio_pci_liveupdate_can_preserve,
> +	.preserve = vfio_pci_liveupdate_preserve,
> +	.unpreserve = vfio_pci_liveupdate_unpreserve,
> +	.retrieve = vfio_pci_liveupdate_retrieve,
> +	.finish = vfio_pci_liveupdate_finish,
> +	.owner = THIS_MODULE,
> +};
> +
> +static struct liveupdate_file_handler vfio_pci_liveupdate_fh = {
> +	.ops = &vfio_pci_liveupdate_file_ops,
> +	.compatible = VFIO_PCI_LUO_FH_COMPATIBLE,
> +};
> +
> +int __init vfio_pci_liveupdate_init(void)
> +{
> +	if (!liveupdate_enabled())
> +		return 0;
> +
> +	return liveupdate_register_file_handler(&vfio_pci_liveupdate_fh);
> +}

liveupdate_register_file_handler() "pins" vfio-pci with a
try_module_get().  Since this is done in our module_init function and
unregister occurs in our module_exit function, rather than relative
to any actual device binding or usage, this means vfio-pci CANNOT be
unloaded.  That seems bad.  Thanks,

Alex

> +
> +void vfio_pci_liveupdate_cleanup(void)
> +{
> +	if (!liveupdate_enabled())
> +		return;
> +
> +	liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh);
> +}