[PATCH v5 00/20] vfio/pci: Base Live Update support for VFIO

[Vipin Sharma <vipinsh@google.com>]

Hello,

This series can be found on Github:

  https://github.com/shvipin/linux vfio/liveupdate/v5

This series provides the base support to enable Live Update feature for
VFIO PCI devices using the Live Update Orchestrator (LUO) and Kexec
Handover (KHO).

Overview
--------

This series makes the following changes to support VFIO Live Update:

 - Puts VFIO Live Update support behind the CONFIG_VFIO_PCI_LIVEUPDATE
   config option (which requires CONFIG_VFIO_DEVICE_CDEV).
 - Preserves VFIO cdev device FDs across a kexec Live Update session via
   LUO/KHO.
 - Enforces that incoming preserved devices can only be retrieved via
   LIVEUPDATE_SESSION_RETRIEVE_FD post-kexec (preventing legacy
   group/cdev opens from accessing uninitialized state).
 - Quiesces the device prior to kexec in freeze() by resetting hardware,
   disabling bus mastering, and marking the device frozen to reject
   post-freeze IO/MMIO.
 - Includes VFIO selftests (uapi & kexec tests with continuous DMA
   checks) and kernel documentation.

VFIO PCI Live Update Roadmap
----------------------------

We are planning to add VFIO PCI Live Update support in phases. Since full
support of this feature will come in phase, VFIO PCI Liveupdate is
controlled by CONFIG_VFIO_PCI_LIVEUPDATE config option. 

This series is phase 1 below:

 1. PCIe function (non-VF) preserved across Live Update without changing
    BDF
 2. PCIe function (non-VF) preserved across Live Update without resetting
 3. PCIe function (non-VF) preserved across Live Update with continuous
    DMA (noiommu)
 4. PCIe function (non-VF) preserved across Live Update with continuous
    DMA (iommufd)
 5. PCIe VF preserved across Live Update with continuous DMA (iommufd)

Dependencies
------------

This series has following dependencies as shown in the diagram

    |---------------------------|
    |         VFIO v5           |  <--- Sent in this series.
    |---------------------------|
    |  Liveupdate Selftests[1]  |
    |---------------------------|
    |        PCI v7 [2]         |
    |---------------------------|

[1] https://lore.kernel.org/all/20260511201155.1488670-1-vipinsh@google.com/
    These selftests changes are needed by other selftests also (iommu,
    kvm), so, I have sent them separately.

[2] https://lore.kernel.org/linux-pci/20260710212616.1351130-1-dmatlack@google.com/
    This is the PCI v7, which adds the live update support in PCI core.

Github branch I have mentioned at the top has all of these dependencies.

Testing
-------

Tested using VFIO Live Update selftests in both QEMU and bare-metal
environment (Intel DSA PCIe device).

  $ ./setup.sh 0000:00:04.0
  $ ./vfio_pci_liveupdate_kexec_test --stage 1 0000:6a:01.0
  $ kexec --reuse-cmdline -l -s /boot/vmlinuz
  $ kexec -e
  $ ./setup.sh 0000:00:04.0
  $ ./vfio_pci_liveupdate_kexec_test --stage 2 0000:6a:01.0

Kernel command line options used:
  - liveupdate=on
  - kho=on
  - vfio_iommu_type1.allow_unsafe_interrupts=Y
  - vfio_pci.enable_sriov=Y
  - vfio_pci.disable_denylist=Y
  - vfio.enable_unsafe_noiommu_mode=Y


Changelog
---------

v5:
 - Addressed Sashiko feedback.
 - Removed condition to disable CONFIG_VFIO_PCI_DMABUF.
 - Expanded vfio_find_device() helper to safely discover a registered
   vfio_device by matching criteria. Internal Sashiko instance found
   data race.
 - Updated selftests to latest changes in VFIO selftests.
 - Rebased on top of PCI Live Update series v7.

v4: https://lore.kernel.org/kvm/20260511234802.2280368-1-vipinsh@google.com/

v3: https://lore.kernel.org/kvm/20260323235817.1960573-1-dmatlack@google.com/

v2: https://lore.kernel.org/kvm/20260129212510.967611-1-dmatlack@google.com/

v1: https://lore.kernel.org/kvm/20251126193608.2678510-1-dmatlack@google.com/

rfc: https://lore.kernel.org/kvm/20251018000713.677779-1-vipinsh@google.com/


David Matlack (7):
  vfio: Enforce preserved devices are retrieved via
    LIVEUPDATE_SESSION_RETRIEVE_FD
  docs: liveupdate: Add documentation for VFIO PCI
  vfio: selftests: Add vfio_pci_liveupdate_uapi_test
  vfio: selftests: Add Makefile support for TEST_GEN_PROGS_EXTENDED
  vfio: selftests: Expose iommu_modes to tests
  vfio: selftests: Verify that opening VFIO device fails during Live
    Update
  vfio: selftests: Add continuous DMA to vfio_pci_liveupdate_kexec_test

Vipin Sharma (13):
  vfio/pci: Factor out the reset logic in VFIO PCI device close path
  vfio: Export various helpers from VFIO
  vfio/pci: Export vfio_pci_dma_buf_move for vfio-pci module
  liveupdate: Export symbols needed by modules
  vfio/pci: Register a file handler with Live Update Orchestrator
  vfio/pci: Preserve vfio-pci device files across Live Update
  vfio: Introduce vfio_find_device() helper
  vfio: Refactor vfio_device_fops_cdev_open()
  vfio: Add API to open cdev device for Live Update restore
  vfio/pci: Retrieve preserved device files after Live Update
  vfio: selftests: Build liveupdate library in VFIO selftests
  vfio: selftests: Initialize vfio_pci_device using a VFIO cdev FD
  vfio: selftests: Add vfio_pci_liveupdate_kexec_test

 Documentation/core-api/liveupdate.rst         |   1 +
 .../driver-api/vfio_pci_liveupdate.rst        |  23 ++
 MAINTAINERS                                   |   2 +
 drivers/vfio/device_cdev.c                    |  67 +++-
 drivers/vfio/group.c                          |   9 +
 drivers/vfio/pci/Kconfig                      |  12 +
 drivers/vfio/pci/Makefile                     |   1 +
 drivers/vfio/pci/vfio_pci.c                   |  13 +-
 drivers/vfio/pci/vfio_pci_config.c            |   3 +
 drivers/vfio/pci/vfio_pci_core.c              | 119 +++---
 drivers/vfio/pci/vfio_pci_dmabuf.c            |   1 +
 drivers/vfio/pci/vfio_pci_liveupdate.c        | 340 ++++++++++++++++++
 drivers/vfio/pci/vfio_pci_priv.h              |  28 ++
 drivers/vfio/vfio.h                           |  18 +
 drivers/vfio/vfio_main.c                      |  67 +++-
 include/linux/kho/abi/vfio_pci.h              |  43 +++
 include/linux/vfio.h                          |  12 +
 include/linux/vfio_pci_core.h                 |   3 +
 kernel/liveupdate/luo_file.c                  |   2 +
 tools/testing/selftests/vfio/Makefile         |  23 +-
 .../vfio/lib/include/libvfio/iommu.h          |   2 +
 .../lib/include/libvfio/vfio_pci_device.h     |   3 +
 tools/testing/selftests/vfio/lib/iommu.c      |   4 +-
 .../selftests/vfio/lib/vfio_pci_device.c      |  25 +-
 .../vfio/vfio_pci_liveupdate_kexec_test.c     | 256 +++++++++++++
 .../vfio/vfio_pci_liveupdate_uapi_test.c      |  97 +++++
 26 files changed, 1097 insertions(+), 77 deletions(-)
 create mode 100644 Documentation/driver-api/vfio_pci_liveupdate.rst
 create mode 100644 drivers/vfio/pci/vfio_pci_liveupdate.c
 create mode 100644 include/linux/kho/abi/vfio_pci.h
 create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c
 create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c


base-commit: cbf37fff757e87376e80e11a8378393a8f25145f
prerequisite-patch-id: 85705fb54d3065efe1d87ab4b69e828a9f3404e7
prerequisite-patch-id: a33ae79b5fc0259bd013b430c18cc3d14a678599
-- 
2.55.0.795.g602f6c329a-goog