Re: [PATCH v6 04/27] vfio/pci: Register a file handler with Live Update Orchestrator

[Vipin Sharma <vipinsh@google.com>]

On Fri, Nov 06, 2026 at 10:29:06PM +0000, Samiullah Khawaja wrote:
> On Mon, Nov 02, 2026 at 07:36:33AM -0800, Vipin Sharma wrote:
> > Register a live update file handler for vfio-pci device files. Add stub
> > implementations of all required callbacks so that registration does not
> > fail. Register it with both live update framework and PCI subsystem.
> > 
> > This file handler will be extended in subsequent commits to enable a
> > device bound to vfio-pci to run without interruption while the host is
> > going through a kexec Live Update.
> > 
> > Put this support behind a new Kconfig VFIO_PCI_LIVEUPDATE. Initial
> > support is added for no-iommu model vfio-pci devices.
> > 
> > Co-developed-by: David Matlack <dmatlack@google.com>
> > Signed-off-by: David Matlack <dmatlack@google.com>
> > Signed-off-by: Vipin Sharma <vipinsh@google.com>
> > ---
> > MAINTAINERS                            |  1 +
> > drivers/vfio/pci/Kconfig               | 11 ++++
> > drivers/vfio/pci/Makefile              |  1 +
> > drivers/vfio/pci/vfio_pci.c            | 11 +++-
> > drivers/vfio/pci/vfio_pci_liveupdate.c | 75 ++++++++++++++++++++++++++
> > drivers/vfio/pci/vfio_pci_priv.h       | 14 +++++
> > include/linux/kho/abi/vfio_pci.h       | 28 ++++++++++
> > 7 files changed, 140 insertions(+), 1 deletion(-)
> > create mode 100644 drivers/vfio/pci/vfio_pci_liveupdate.c
> > create mode 100644 include/linux/kho/abi/vfio_pci.h
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 5d1b58271989..167aa9d66ce8 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -28662,6 +28662,7 @@ F:	Documentation/ABI/testing/debugfs-vfio
> > F:	Documentation/ABI/testing/sysfs-devices-vfio-dev
> > F:	Documentation/driver-api/vfio.rst
> > F:	drivers/vfio/
> > +F:	include/linux/kho/abi/vfio_pci.h
> > F:	include/linux/vfio.h
> > F:	include/linux/vfio_pci_core.h
> > F:	include/uapi/linux/vfio.h
> > diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> > index 296bf01e185e..e8285ad93a69 100644
> > --- a/drivers/vfio/pci/Kconfig
> > +++ b/drivers/vfio/pci/Kconfig
> > @@ -42,6 +42,17 @@ 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 in no-iommu mode"
> > +	depends on PCI_LIVEUPDATE && VFIO_NOIOMMU
> 
> Can we handle this dependency in code instead of doing through
> configs? Are there any build dependencies on noiommu?

I can remove it but then by itself VFIO series will enable LIVEUPDATE
irrespective of VFIO_NOIOMMU and it will just fail when someone tries to
enable it. So, kconfig looks cleaner to me.

Can your series modify this kconfig and add (VFIO_NOIOMMU ||
IOMMU_LIVEUPDATE)? Will that work for you?