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Message-ID: <20260129212510.967611-5-dmatlack@google.com>
Date: Thu, 29 Jan 2026 21:24:51 +0000
From: David Matlack <dmatlack@...gle.com>
To: Alex Williamson <alex@...zbot.org>
Cc: Adithya Jayachandran <ajayachandra@...dia.com>, Alexander Graf <graf@...zon.com>,
Alex Mastro <amastro@...com>, Alistair Popple <apopple@...dia.com>,
Andrew Morton <akpm@...ux-foundation.org>, Ankit Agrawal <ankita@...dia.com>,
Bjorn Helgaas <bhelgaas@...gle.com>, Chris Li <chrisl@...nel.org>,
David Matlack <dmatlack@...gle.com>, David Rientjes <rientjes@...gle.com>,
Jacob Pan <jacob.pan@...ux.microsoft.com>, Jason Gunthorpe <jgg@...dia.com>,
Jason Gunthorpe <jgg@...pe.ca>, Jonathan Corbet <corbet@....net>, Josh Hilke <jrhilke@...gle.com>,
Kevin Tian <kevin.tian@...el.com>, kexec@...ts.infradead.org, kvm@...r.kernel.org,
Leon Romanovsky <leon@...nel.org>, Leon Romanovsky <leonro@...dia.com>, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-mm@...ck.org, linux-pci@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
"Michał Winiarski" <michal.winiarski@...el.com>, Mike Rapoport <rppt@...nel.org>,
Parav Pandit <parav@...dia.com>, Pasha Tatashin <pasha.tatashin@...een.com>,
Pranjal Shrivastava <praan@...gle.com>, Pratyush Yadav <pratyush@...nel.org>,
Raghavendra Rao Ananta <rananta@...gle.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
Saeed Mahameed <saeedm@...dia.com>, Samiullah Khawaja <skhawaja@...gle.com>,
Shuah Khan <skhan@...uxfoundation.org>,
"Thomas Hellström" <thomas.hellstrom@...ux.intel.com>, Tomita Moeko <tomitamoeko@...il.com>,
Vipin Sharma <vipinsh@...gle.com>, Vivek Kasireddy <vivek.kasireddy@...el.com>,
William Tu <witu@...dia.com>, Yi Liu <yi.l.liu@...el.com>, Zhu Yanjun <yanjun.zhu@...ux.dev>
Subject: [PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator
From: Vipin Sharma <vipinsh@...gle.com>
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 <vipinsh@...gle.com>
Co-developed-by: David Matlack <dmatlack@...gle.com>
Signed-off-by: David Matlack <dmatlack@...gle.com>
---
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 <vipinsh@...gle.com>
+ * David Matlack <dmatlack@...gle.com>
+ */
+
+#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)
+{
+ 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 <vipinsh@...gle.com>
+ * David Matlack <dmatlack@...gle.com>
+ */
+
+#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
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