From: Vipin Sharma <[email protected]> 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. Put this support behind a new Kconfig VFIO_PCI_LIVEUPDATE that is marked experimental and default-disabled until more of the device preservation support has landed in the kernel. Signed-off-by: Vipin Sharma <[email protected]> Co-developed-by: David Matlack <[email protected]> Signed-off-by: David Matlack <[email protected]> --- MAINTAINERS | 1 + drivers/vfio/pci/Kconfig | 11 ++++ drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/vfio_pci.c | 12 ++++- drivers/vfio/pci/vfio_pci_liveupdate.c | 69 ++++++++++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 14 ++++++ include/linux/kho/abi/vfio_pci.h | 28 +++++++++++ 7 files changed, 135 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 96ea84948d76..a16a7ecc67a4 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -27685,6 +27685,7 @@ 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 1e82b44bda1a..8f087f7b58c3 100644 --- a/drivers/vfio/pci/Kconfig +++ b/drivers/vfio/pci/Kconfig @@ -58,6 +58,17 @@ config VFIO_PCI_ZDEV_KVM config VFIO_PCI_DMABUF def_bool y if VFIO_PCI_CORE && PCI_P2PDMA && DMA_SHARED_BUFFER +config VFIO_PCI_LIVEUPDATE + bool "VFIO PCI support for Live Update (EXPERIMENTAL)" + depends on VFIO_PCI && PCI_LIVEUPDATE + help + Support for preserving devices bound to vfio-pci across a Live + Update. This option should only be enabled by developers working on + implementing this support. Once enough support has landed in the + kernel, this option will no longer be marked EXPERIMENTAL. + + If you don't know what to do here, say N. + source "drivers/vfio/pci/mlx5/Kconfig" source "drivers/vfio/pci/hisilicon/Kconfig" diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile index e0a0757dd1d2..f462df61edb9 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-$(CONFIG_VFIO_PCI_LIVEUPDATE) += vfio_pci_liveupdate.o obj-$(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..41dcbe4ace67 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -170,6 +170,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) ret = vfio_pci_core_register_device(vdev); if (ret) goto out_put_vdev; + return 0; out_put_vdev: @@ -264,10 +265,14 @@ static int __init vfio_pci_init(void) vfio_pci_core_set_params(nointxmask, is_disable_vga, disable_idle_d3); + ret = vfio_pci_liveupdate_init(); + if (ret) + return ret; + /* Register and scan for devices */ ret = pci_register_driver(&vfio_pci_driver); if (ret) - return ret; + goto err_liveupdate_cleanup; vfio_pci_fill_ids(); @@ -275,12 +280,17 @@ static int __init vfio_pci_init(void) pr_warn("device denylist disabled.\n"); return 0; + +err_liveupdate_cleanup: + vfio_pci_liveupdate_cleanup(); + return ret; } 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..5ea5af46b159 --- /dev/null +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c @@ -0,0 +1,69 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (c) 2026, Google LLC. + * Vipin Sharma <[email protected]> + * David Matlack <[email protected]> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kho/abi/vfio_pci.h> +#include <linux/liveupdate.h> +#include <linux/errno.h> + +#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) +{ + int ret; + + ret = liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); + if (ret && ret != -EOPNOTSUPP) + return ret; + + return 0; +} + +void vfio_pci_liveupdate_cleanup(void) +{ + 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..cbf46e09da30 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_VFIO_PCI_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_VFIO_PCI_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..e2412b455e61 --- /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 <[email protected]> + * David Matlack <[email protected]> + */ + +#ifndef _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H +#define _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H + +/** + * DOC: VFIO PCI Live Update ABI + * + * VFIO uses the ABI defined below for preserving 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 */ -- 2.53.0.983.g0bb29b3bc5-goog
