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Thu, 29 Jan 2026 13:25:44 -0800 (PST) Date: Thu, 29 Jan 2026 21:24:51 +0000 In-Reply-To: <20260129212510.967611-1-dmatlack@google.com> Mime-Version: 1.0 References: <20260129212510.967611-1-dmatlack@google.com> X-Mailer: git-send-email 2.53.0.rc1.225.gd81095ad13-goog Message-ID: <20260129212510.967611-5-dmatlack@google.com> Subject: [PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator 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_132547_616979_302AB776 X-CRM114-Status: GOOD ( 24.29 ) 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 From: Vipin Sharma Register a live update file handler for vfio-pci device files. Add stub implementations of all required callbacks so that registration does not fail (i.e. to avoid breaking git-bisect). 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. Signed-off-by: Vipin Sharma Co-developed-by: David Matlack Signed-off-by: David Matlack --- MAINTAINERS | 1 + drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/vfio_pci.c | 9 +++- drivers/vfio/pci/vfio_pci_liveupdate.c | 69 ++++++++++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 14 ++++++ include/linux/kho/abi/vfio_pci.h | 28 +++++++++++ 6 files changed, 121 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 a671e3d4e8be..7d6cdecedb05 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -27520,6 +27520,7 @@ 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/Makefile b/drivers/vfio/pci/Makefile index e0a0757dd1d2..23305ebc418b 100644 --- a/drivers/vfio/pci/Makefile +++ b/drivers/vfio/pci/Makefile @@ -7,6 +7,7 @@ obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o vfio-pci-y := vfio_pci.o vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o +vfio-pci-$(CONFIG_LIVEUPDATE) += vfio_pci_liveupdate.o obj-$(CONFIG_VFIO_PCI) += vfio-pci.o obj-$(CONFIG_MLX5_VFIO_PCI) += mlx5/ diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 0c771064c0b8..19e88322af2c 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -258,6 +258,10 @@ static int __init vfio_pci_init(void) int ret; bool is_disable_vga = true; + ret = vfio_pci_liveupdate_init(); + if (ret) + return ret; + #ifdef CONFIG_VFIO_PCI_VGA is_disable_vga = disable_vga; #endif @@ -266,8 +270,10 @@ static int __init vfio_pci_init(void) /* Register and scan for devices */ ret = pci_register_driver(&vfio_pci_driver); - if (ret) + if (ret) { + vfio_pci_liveupdate_cleanup(); return ret; + } vfio_pci_fill_ids(); @@ -281,6 +287,7 @@ module_init(vfio_pci_init); static void __exit vfio_pci_cleanup(void) { pci_unregister_driver(&vfio_pci_driver); + vfio_pci_liveupdate_cleanup(); } module_exit(vfio_pci_cleanup); diff --git a/drivers/vfio/pci/vfio_pci_liveupdate.c b/drivers/vfio/pci/vfio_pci_liveupdate.c new file mode 100644 index 000000000000..b84e63c0357b --- /dev/null +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c @@ -0,0 +1,69 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (c) 2025, Google LLC. + * Vipin Sharma + * David Matlack + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include + +#include "vfio_pci_priv.h" + +static bool vfio_pci_liveupdate_can_preserve(struct liveupdate_file_handler *handler, + struct file *file) +{ + return false; +} + +static int vfio_pci_liveupdate_preserve(struct liveupdate_file_op_args *args) +{ + return -EOPNOTSUPP; +} + +static void vfio_pci_liveupdate_unpreserve(struct liveupdate_file_op_args *args) +{ +} + +static int vfio_pci_liveupdate_retrieve(struct liveupdate_file_op_args *args) +{ + return -EOPNOTSUPP; +} + +static void vfio_pci_liveupdate_finish(struct liveupdate_file_op_args *args) +{ +} + +static const struct liveupdate_file_ops vfio_pci_liveupdate_file_ops = { + .can_preserve = vfio_pci_liveupdate_can_preserve, + .preserve = vfio_pci_liveupdate_preserve, + .unpreserve = vfio_pci_liveupdate_unpreserve, + .retrieve = vfio_pci_liveupdate_retrieve, + .finish = vfio_pci_liveupdate_finish, + .owner = THIS_MODULE, +}; + +static struct liveupdate_file_handler vfio_pci_liveupdate_fh = { + .ops = &vfio_pci_liveupdate_file_ops, + .compatible = VFIO_PCI_LUO_FH_COMPATIBLE, +}; + +int __init vfio_pci_liveupdate_init(void) +{ + if (!liveupdate_enabled()) + return 0; + + return liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); +} + +void vfio_pci_liveupdate_cleanup(void) +{ + if (!liveupdate_enabled()) + return; + + liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh); +} diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h index 27ac280f00b9..68966ec64e51 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -133,4 +133,18 @@ static inline void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, } #endif +#ifdef CONFIG_LIVEUPDATE +int __init vfio_pci_liveupdate_init(void); +void vfio_pci_liveupdate_cleanup(void); +#else +static inline int vfio_pci_liveupdate_init(void) +{ + return 0; +} + +static inline void vfio_pci_liveupdate_cleanup(void) +{ +} +#endif /* CONFIG_LIVEUPDATE */ + #endif diff --git a/include/linux/kho/abi/vfio_pci.h b/include/linux/kho/abi/vfio_pci.h new file mode 100644 index 000000000000..37a845eed972 --- /dev/null +++ b/include/linux/kho/abi/vfio_pci.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copyright (c) 2025, Google LLC. + * Vipin Sharma + * David Matlack + */ + +#ifndef _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H +#define _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H + +/** + * DOC: VFIO PCI Live Update ABI + * + * This header defines the ABI for preserving the state of a VFIO PCI device + * files across a kexec reboot using LUO. + * + * Device metadata is serialized into memory which is then handed to the next + * kernel via KHO. + * + * This interface is a contract. Any modification to any of the serialization + * structs defined here constitutes a breaking change. Such changes require + * incrementing the version number in the VFIO_PCI_LUO_FH_COMPATIBLE string. + */ + +#define VFIO_PCI_LUO_FH_COMPATIBLE "vfio-pci-v1" + +#endif /* _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H */ -- 2.53.0.rc1.225.gd81095ad13-goog