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

Alex Williamson
2026-02-25T21:33:38Z

On Thu, 29 Jan 2026 21:24:51 +0000
David Matlack <dmatlack@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);
> +}