Re: [PATCH v8 01/12] PCI: liveupdate: Set up FLB handler for the PCI core

[Samiullah Khawaja]

On Tue, Jul 28, 2026 at 10:09:55PM +0000, David Matlack wrote:
> Set up a File-Lifecycle-Bound (FLB) handler for the PCI core to enable
> it to participate in the preservation of PCI devices across Live Update.
> Essentially, this commit enables the PCI core to allocate a struct
> (struct pci_ser) and preserve it across a Live Update whenever at least
> one device is preserved.
>
> Preserving PCI devices across Live Update is built on top of the Live
> Update Orchestrator's (LUO) support for file preservation. Drivers are
> expected to expose a file to userspace to represent a single PCI device
> and support preservation of that file. This is intended primarily to
> support preservation of PCI devices bound to VFIO drivers.
>
> This commit enables drivers to register their liveupdate_file_handler
> with the PCI core so that the PCI core can do its own tracking and
> enforcement of which devices are preserved.
>
>  pci_liveupdate_register_flb(driver_file_handler);
>  pci_liveupdate_unregister_flb(driver_file_handler);
>
> When the first file (with a handler registered with the PCI core) is
> preserved, the PCI core will be notified to allocate its tracking struct
> (pci_ser). When the last file is unpreserved (i.e. preservation
> cancelled) the PCI core will be notified to free struct pci_ser.
>
> This struct is preserved across a Live Update using KHO and can be
> fetched by the PCI core during early boot (e.g. during device
> enumeration) so that it knows which devices were preserved.
>
> Note: This commit only allocates struct pci_ser and preserves it across
> Live Update. A subsequent commit will add an API for drivers to tell the
> PCI core exactly which devices are being preserved.
>
> Note: There is no reason to check for kho_is_enabled() since it can be
> assumed to return true. If KHO was not enabled then Live Update would
> not be enabled and these routines would never run.
>
> Reviewed-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> Documentation/core-api/liveupdate.rst |   4 +
> MAINTAINERS                           |  13 +++
> drivers/pci/Kconfig                   |  15 +++
> drivers/pci/Makefile                  |   1 +
> drivers/pci/liveupdate.c              | 158 ++++++++++++++++++++++++++
> include/linux/kho/abi/pci.h           |  63 ++++++++++
> include/linux/pci.h                   |   1 +
> include/linux/pci_liveupdate.h        |  30 +++++
> 8 files changed, 285 insertions(+)
> create mode 100644 drivers/pci/liveupdate.c
> create mode 100644 include/linux/kho/abi/pci.h
> create mode 100644 include/linux/pci_liveupdate.h

Reviewed-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>

Thanks,
Sami