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Thu, 29 Jan 2026 13:25:37 -0800 (PST) Date: Thu, 29 Jan 2026 21:24:47 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.rc1.225.gd81095ad13-goog Message-ID: <20260129212510.967611-1-dmatlack@google.com> Subject: [PATCH v2 00/22] vfio/pci: Base Live Update support for VFIO device files From: David Matlack To: Alex Williamson Cc: Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Matlack , David Rientjes , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Lukas Wunner , "=?UTF-8?q?Micha=C5=82=20Winiarski?=" , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , "=?UTF-8?q?Thomas=20Hellstr=C3=B6m?=" , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260129_132539_562125_88F3B404 X-CRM114-Status: GOOD ( 19.99 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org This series can be found on GitHub: https://github.com/dmatlack/linux/tree/liveupdate/vfio/cdev/v2 This series adds the base support to preserve a VFIO device file across a Live Update. "Base support" means that this allows userspace to safely preserve a VFIO device file with LIVEUPDATE_SESSION_PRESERVE_FD and retrieve it with LIVEUPDATE_SESSION_RETRIEVE_FD, but the device itself is not preserved in a fully running state across Live Update. This series aims to provide a foundation on which to build the rest of the device preservation infrastructure, including: - Preservation of iommufd files [1] - Preservation of IOMMU driver state - Preservation of PCI state (BAR resources, device state, bridge state, ...) - Preservation of vfio-pci driver state Testing ------- The patches at the end of this series provide comprehensive selftests for the new code added by this series. The selftests have been validated in both a VM environment using a virtio-net PCIe device, and in a baremetal environment on an Intel EMR server with an Intel DSA PCIe device. Here is an example of how to run the new selftests: vfio_pci_liveupdate_uapi_test: $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test 0000:00:04.0 $ tools/testing/selftests/vfio/scripts/cleanup.sh vfio_pci_liveupdate_kexec_test: $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test --stage 1 0000:00:04.0 $ kexec ... $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test --stage 2 0000:00:04.0 $ tools/testing/selftests/vfio/scripts/cleanup.sh It is also possible to run vfio_pci_liveupdate_kexec_test multiple times to preserve multiple devices simultaneously across a Live Update. This series has been tested with up to 8 devices concurrently preserved. Changelog --------- v2: - Rebase on top of linux-next (tag: next-20260115) - Add missing EXPORT_SYMBOL_GPLs in LUO (Zhu) - Add Missing EXPORT_SYMBOL_GPLs for vfio_device_fops (Zhu) - Fix circular dependency between vfio-pci-core and vfio-pci (Zhu) - Handle pci=assign-busses (Lukas) - Drop driver_override patch (Jason) - Use kho_alloc_preserve(), kho_unpreserve_free(), kho_restore_free() (Pasha) - Don't access PCI FLB after device initialization (Jason) - Fix folio leak in vfio_pci_liveupdate_retrieve() (Alex) - Add Documentation (Pasha) v1: https://lore.kernel.org/kvm/20251126193608.2678510-1-dmatlack@google.com/ rfc: https://lore.kernel.org/kvm/20251018000713.677779-1-vipinsh@google.com/ Cc: Saeed Mahameed Cc: Adithya Jayachandran Cc: Jason Gunthorpe Cc: Parav Pandit Cc: Leon Romanovsky Cc: William Tu Cc: Jacob Pan Cc: Lukas Wunner Cc: Pasha Tatashin Cc: Mike Rapoport Cc: Pratyush Yadav Cc: Samiullah Khawaja Cc: Chris Li Cc: Josh Hilke Cc: David Rientjes [1] https://lore.kernel.org/linux-iommu/20251202230303.1017519-1-skhawaja@google.com/ David Matlack (13): liveupdate: Export symbols needed by modules PCI: Add API to track PCI devices preserved across Live Update PCI: Inherit bus numbers from previous kernel during Live Update vfio/pci: Notify PCI subsystem about devices preserved across Live Update vfio: Enforce preserved devices are retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD vfio/pci: Store incoming Live Update state in struct vfio_pci_core_device docs: liveupdate: Document VFIO device file preservation vfio: selftests: Add Makefile support for TEST_GEN_PROGS_EXTENDED vfio: selftests: Add vfio_pci_liveupdate_uapi_test vfio: selftests: Expose iommu_modes to tests vfio: selftests: Expose low-level helper routines for setting up struct vfio_pci_device vfio: selftests: Verify that opening VFIO device fails during Live Update vfio: selftests: Add continuous DMA to vfio_pci_liveupdate_kexec_test Vipin Sharma (9): vfio/pci: Register a file handler with Live Update Orchestrator vfio/pci: Preserve vfio-pci device files across Live Update vfio/pci: Retrieve preserved device files after Live Update vfio/pci: Skip reset of preserved device after Live Update selftests/liveupdate: Move luo_test_utils.* into a reusable library selftests/liveupdate: Add helpers to preserve/retrieve FDs 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/userspace-api/liveupdate.rst | 144 ++++++++++ MAINTAINERS | 1 + drivers/pci/Makefile | 1 + drivers/pci/liveupdate.c | 212 +++++++++++++++ drivers/pci/probe.c | 23 +- drivers/vfio/device_cdev.c | 25 +- drivers/vfio/group.c | 9 + drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/vfio_pci.c | 11 +- drivers/vfio/pci/vfio_pci_core.c | 24 +- drivers/vfio/pci/vfio_pci_liveupdate.c | 246 +++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 16 ++ drivers/vfio/vfio.h | 13 - drivers/vfio/vfio_main.c | 23 +- include/linux/kho/abi/pci.h | 55 ++++ include/linux/kho/abi/vfio_pci.h | 45 +++ include/linux/pci.h | 47 ++++ include/linux/vfio.h | 58 ++++ include/linux/vfio_pci_core.h | 2 + kernel/liveupdate/luo_core.c | 1 + kernel/liveupdate/luo_file.c | 2 + tools/testing/selftests/liveupdate/.gitignore | 1 + tools/testing/selftests/liveupdate/Makefile | 14 +- .../include/libliveupdate.h} | 11 +- .../selftests/liveupdate/lib/libliveupdate.mk | 20 ++ .../{luo_test_utils.c => lib/liveupdate.c} | 43 ++- .../selftests/liveupdate/luo_kexec_simple.c | 2 +- .../selftests/liveupdate/luo_multi_session.c | 2 +- tools/testing/selftests/vfio/Makefile | 23 +- .../vfio/lib/include/libvfio/iommu.h | 2 + .../lib/include/libvfio/vfio_pci_device.h | 8 + tools/testing/selftests/vfio/lib/iommu.c | 4 +- .../selftests/vfio/lib/vfio_pci_device.c | 60 ++-- .../vfio/vfio_pci_liveupdate_kexec_test.c | 256 ++++++++++++++++++ .../vfio/vfio_pci_liveupdate_uapi_test.c | 93 +++++++ 35 files changed, 1410 insertions(+), 88 deletions(-) create mode 100644 drivers/pci/liveupdate.c create mode 100644 drivers/vfio/pci/vfio_pci_liveupdate.c create mode 100644 include/linux/kho/abi/pci.h create mode 100644 include/linux/kho/abi/vfio_pci.h rename tools/testing/selftests/liveupdate/{luo_test_utils.h => lib/include/libliveupdate.h} (80%) create mode 100644 tools/testing/selftests/liveupdate/lib/libliveupdate.mk rename tools/testing/selftests/liveupdate/{luo_test_utils.c => lib/liveupdate.c} (89%) 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: 9b7977f9e39b7768c70c2aa497f04e7569fd3e00 -- 2.53.0.rc1.225.gd81095ad13-goog