Re: [PATCH v5 05/20] vfio/pci: Register a file handler with Live Update Orchestrator

[Vipin Sharma <vipinsh@google.com>]

On Tue, Jul 14, 2026 at 03:28:56PM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
> - [High] The Kconfig option VFIO_PCI_LIVEUPDATE depends on a non-existent configuration symbol PCI_LIVEUPDATE.
> - [High] Calls to undeclared and undefined functions pci_liveupdate_register_flb() and pci_liveupdate_unregister_flb().
> - [High] Masking -EOPNOTSUPP on FLB registration failure leads to a double unregistration of the file handler and potential kernel panic.
> --
> 
> --- Patch [5]: [PATCH v5 05/20] vfio/pci: Register a file handler with Live Update Orchestrator ---
> commit a3c1a8c69f4b2c27d2e063cca84eb003906e3bbf
> Author: Vipin Sharma <vipinsh@google.com>
> 
> vfio/pci: Register a file handler with Live Update Orchestrator
> 
> This commit adds a live update file handler for vfio-pci device files
> with stub implementations. It registers the handler with the live update
> framework and PCI subsystem, gated behind a new VFIO_PCI_LIVEUPDATE option.
> 
> > diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> > index 296bf01e185ec..c12d614fc6c4a 100644
> > --- a/drivers/vfio/pci/Kconfig
> > +++ b/drivers/vfio/pci/Kconfig
> [ ... ]
> > @@ -42,6 +42,18 @@ config VFIO_PCI_IGD
> >  	  and LPC bridge config space.
> >  
> >  	  To enable Intel IGD assignment through vfio-pci, say Y.
> > +
> > +config VFIO_PCI_LIVEUPDATE
> > +	bool "VFIO PCI support for Live Update (EXPERIMENTAL)"
> > +	depends on PCI_LIVEUPDATE
> 
> [Severity: High]
> Does the PCI_LIVEUPDATE configuration symbol exist anywhere in the kernel
> tree? It appears this dependency cannot be met, preventing the new
> VFIO_PCI_LIVEUPDATE option from being selected.

This series is built on top of an in-progress series as explained in
the cover letter.
https://lore.kernel.org/linux-pci/20260710212616.1351130-1-dmatlack@google.com/

> 
> > +	help
> > +	  Support for preserving devices bound to vfio-pci across a Live
> [ ... ]
> > diff --git a/drivers/vfio/pci/vfio_pci_liveupdate.c b/drivers/vfio/pci/vfio_pci_liveupdate.c
> > new file mode 100644
> > index 0000000000000..803528c9f1b27
> > --- /dev/null
> > +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c
> [ ... ]
> > +int __init vfio_pci_liveupdate_init(void)
> > +{
> > +	int ret;
> > +
> > +	ret = liveupdate_register_file_handler(&vfio_pci_liveupdate_fh);
> > +	if (ret)
> > +		goto err_return;
> > +
> > +	ret = pci_liveupdate_register_flb(&vfio_pci_liveupdate_fh);
> 
> [Severity: High]
> Are pci_liveupdate_register_flb() and pci_liveupdate_unregister_flb()
> declared in any header or defined in any source file? Building with
> this configuration enabled might result in implicit declaration compiler
> errors and fatal linker errors.
> 

Available in the dependent series.

> > +	if (ret)
> > +		goto err_unregister;
> > +
> > +	return 0;
> > +
> > +err_unregister:
> > +	liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh);
> > +err_return:
> > +	return (ret == -EOPNOTSUPP) ? 0 : ret;
> 
> [Severity: High]
> If pci_liveupdate_register_flb() returns -EOPNOTSUPP, this error path
> unregisters the file handler but returns 0. Could this lead to a double
> unregistration when the module is unloaded and vfio_pci_liveupdate_cleanup()
> is called?
> 
> Calling liveupdate_unregister_file_handler() a second time on the already
> removed list node might cause list corruption and a kernel panic.
> 

Yes, this is an issue. I will add the fix in next version. Separately, I
will send a patch to make liveupdate_unregister_file_handler()
idempotent.

> > +}
> > +
> > +void vfio_pci_liveupdate_cleanup(void)
> > +{
> > +	pci_liveupdate_unregister_flb(&vfio_pci_liveupdate_fh);
> > +	liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh);
> > +}
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20260714151505.3466855-1-vipinsh@google.com?part=5