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AJvYcCV67gvwshneULqWa+iJNSpYBLAPMvaOOfOXbXBgchF08c6I9F8IvHia1ZG2O3U436+2wapUllNpqQ==@kvack.org X-Gm-Message-State: AOJu0YwPQP2qoopsv+mlLm/XyN0JHn5b/fyWMDIYN5JgAhAtrLUQycS2 0cKeW2a8dSLEa0qgZzSKyRCf4Lcc8nvNJmskzvoTpm28O65fYr+kMp37CzVBXpZMJltZJl3KYrb RH2r3NnAY42XHrg== X-Received: from pjvp18.prod.google.com ([2002:a17:90a:df92:b0:35b:9822:9f79]) (user=dmatlack job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1a8a:b0:359:f43d:4a6e with SMTP id 98e67ed59e1d1-35bd2996301mr12903584a91.0.1774310327594; Mon, 23 Mar 2026 16:58:47 -0700 (PDT) Date: Mon, 23 Mar 2026 23:57:58 +0000 In-Reply-To: <20260323235817.1960573-1-dmatlack@google.com> Mime-Version: 1.0 References: <20260323235817.1960573-1-dmatlack@google.com> X-Mailer: git-send-email 2.53.0.983.g0bb29b3bc5-goog Message-ID: <20260323235817.1960573-7-dmatlack@google.com> Subject: [PATCH v3 06/24] vfio/pci: Register a file handler with Live Update Orchestrator From: David Matlack To: Alex Williamson , Bjorn Helgaas Cc: Adithya Jayachandran , Alexander Graf , Alex Mastro , Andrew Morton , Ankit Agrawal , Arnd Bergmann , Askar Safin , "Borislav Petkov (AMD)" , Chris Li , Dapeng Mi , David Matlack , David Rientjes , Feng Tang , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kees Cook , 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, Li RongQing , Lukas Wunner , Marco Elver , "=?UTF-8?q?Micha=C5=82=20Winiarski?=" , Mike Rapoport , Parav Pandit , Pasha Tatashin , "Paul E. McKenney" , Pawan Gupta , "Peter Zijlstra (Intel)" , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Randy Dunlap , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 16AD8C0005 X-Stat-Signature: rqkhbhdgupsgp1qeahh7i5uqugs7rj75 X-HE-Tag: 1774310328-111318 X-HE-Meta: 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 nfgDZoOR 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. 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 Co-developed-by: David Matlack Signed-off-by: David Matlack --- 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 + * 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) +{ + 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 + * David Matlack + */ + +#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