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

[Samiullah Khawaja <skhawaja@google.com>]

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?
>+	help
>+	  Support for preserving devices bound to vfio-pci in no-iommu mode
>+	  across a Live Update. It enables a device to continue working (DMA)
>+	  while host kernel is going through a kexec live update.
>+
>+	  If you don't know what to do here, say N.
>+
> endif
>

Thanks,
Sami