On Fri, 22 May 2026 20:24:01 +0000, David Matlack <[email protected]> wrote:
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 10c9b65aa242..e68ae5c172d4 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -330,7 +330,7 @@ config VGA_ARB_MAX_GPUS
>
> config PCI_LIVEUPDATE
> bool "PCI Live Update Support"
> - depends on PCI && LIVEUPDATE
> + depends on PCI && LIVEUPDATE && 64BIT
Please move this to the first patch, fewer changes between patches, and
also KHO does not support anything but 64-bit mode.
>
> diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
> index 065d5af822f7..96c43b84532c 100644
> --- a/drivers/pci/liveupdate.c
> +++ b/drivers/pci/liveupdate.c
> @@ -128,13 +157,49 @@ static void pci_flb_unpreserve(struct
> liveupdate_flb_op_args *args)
> [ ... skip 31 lines ... ]
> +
> +err_xa_destroy:
> + xa_destroy(&incoming->xa);
> + kfree(incoming);
> +err_restore_free:
> + kho_restore_free(ser);
This is the pattern we have been enforcing in other places in LUO. If
the first retrieval fails, return the same error thereafter.
> @@ -270,6 +335,91 @@ void pci_liveupdate_unpreserve(struct pci_dev *dev)
> }
> EXPORT_SYMBOL_GPL(pci_liveupdate_unpreserve);
>
> +static struct pci_flb_incoming *pci_liveupdate_flb_get_incoming(void)
> +{
> + struct pci_flb_incoming *incoming = NULL;
> + int ret;
Maybe make the error return static, and avoid another search through compatible
FLBs if it failed before?
1. Add "saved_err;"; if it is set, return it right away.
2. Change all errors to use goto save_err;, and at the end of the
function, assign ret to saved_err;
> [ ... skip 15 lines ... ]
> + * This could mean that no PCI FLB data was passed by the previous
> + * kernel, but it could also mean the previous kernel used a different
> + * compatibility string (i.e. a different ABI).
> + */
> + if (ret == -ENOENT) {
> + pr_info_once("No incoming FLB matched %s\n",
> pci_liveupdate_flb.compatible);
I would assume this is very normal, e.g., no devices were preserved but
memfd+hugetlb was preserved. Maybe use pr_debug_once().
> + return NULL;
> + }
> +
> + /*
> + * There is incoming FLB data that matches pci_liveupdate_flb.compatible
> + * but it cannot be retrieved.
> + */
> + if (ret) {
> + WARN_ONCE(ret, "Failed to retrieve incoming FLB data\n");
No need to print backtrace, please just print a warning:
pr_warn_once("Failed to retrieve incoming FLB data: %pe\n", ERR_PTR(ret));
> [ ... skip 34 lines ... ]
> + * through pci_liveupdate_finish(). This can happen if PCI core probes
> + * the same device multiple times, e.g. due to hotplug.
> + */
> + if (!dev_ser->refcount) {
> + pci_liveupdate_flb_put_incoming();
> + return;
Pleaes use 'goto put_incoming'
> + }
> +
> + pci_info(dev, "Device was preserved by previous kernel across Live
> Update\n");
> + dev->liveupdate.incoming = dev_ser;
> +
> + /*
> + * Hold the ref on the incoming FLB until pci_liveupdate_finish() so
> + * that dev->liveupdate.incoming does not get freed while it is in use.
> + */
How would that work? If finish is not called FLB stays around until the
next reboot.
--
Pasha Tatashin <[email protected]>
