Merge branch 'lu-pci-preservation' into next

3 files changed, 145 insertions, 0 deletions

diff --git a/include/linux/kho/abi/pci.h b/include/linux/kho/abi/pci.h
new file mode 100644
index 000000000000..9485ed73c351
--- /dev/null
+++ b/include/linux/kho/abi/pci.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Copyright (c) 2026, Google LLC.
+ * David Matlack <dmatlack@google.com>
+ */
+
+#ifndef _LINUX_KHO_ABI_PCI_H
+#define _LINUX_KHO_ABI_PCI_H
+
+#include <linux/bug.h>
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+/**
+ * DOC: PCI File-Lifecycle Bound (FLB) Live Update ABI
+ *
+ * This header defines the ABI for preserving core PCI state across kexec using
+ * Live Update File-Lifecycle Bound (FLB) data.
+ *
+ * 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 PCI_LUO_FLB_VERSION number.
+ */
+
+#define PCI_LUO_FLB_COMPATIBLE "pci"
+#define PCI_LUO_FLB_VERSION 2
+
+/**
+ * struct pci_dev_ser - Serialized state about a single PCI device.
+ *
+ * @domain: The device's PCI domain number (segment).
+ * @bdf: The device's PCI bus, device, and function number.
+ * @refcount: Reference count used by the PCI core to keep track of whether it
+ *            is done using a device's struct pci_dev_ser. The value of the
+ *            refcount is equal to the number of preserved devices at or below
+ *            it in the PCI hierarchy when the struct pci_dev_ser is in use, and
+ *            0 otherwise.
+ */
+struct pci_dev_ser {
+	u32 domain;
+	u16 bdf;
+	u16 refcount;
+} __packed;
+
+/**
+ * struct pci_ser - PCI Subsystem Live Update State
+ *
+ * This struct tracks state about all devices that are being preserved across
+ * a Live Update for the next kernel. It contains only state owned by the PCI
+ * core; the state a driver needs to resume its device is preserved separately
+ * by that driver.
+ *
+ * @version: The version of the "pci" FLB struct. This field must never be
+ *           deleted, moved, or resized, as the kernel depends on always being
+ *           able to check the struct pci_ser version number.
+ * @nr_devices: The number of devices that were preserved.
+ * @devices: Physical address of the first KHO block containing pci_dev_ser.
+ */
+struct pci_ser {
+	u32 version;
+	u32 nr_devices;
+	u64 devices;
+} __packed;
+
+#endif /* _LINUX_KHO_ABI_PCI_H */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d31a8d107b1e..b35ac263c451 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -43,6 +43,7 @@
 #include <uapi/linux/pci.h>
 
 #include <linux/pci_ids.h>
+#include <linux/pci_liveupdate.h>
 
 #define PCI_STATUS_ERROR_BITS (PCI_STATUS_DETECTED_PARITY  | \
 			       PCI_STATUS_SIG_SYSTEM_ERROR | \
@@ -598,6 +599,9 @@ struct pci_dev {
 	u8		tph_mode;	/* TPH mode */
 	u8		tph_req_type;	/* TPH requester type */
 #endif
+#ifdef CONFIG_PCI_LIVEUPDATE
+	struct pci_liveupdate liveupdate;
+#endif
 };
 
 static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
@@ -832,6 +836,9 @@ static inline struct pci_dev *pci_upstream_bridge(struct pci_dev *dev)
 	return dev->bus->self;
 }
 
+#define for_each_pci_dev_in_path(dev) \
+	for (; dev; dev = pci_upstream_bridge(dev))
+
 #ifdef CONFIG_PCI_MSI
 static inline bool pci_dev_msi_enabled(struct pci_dev *pci_dev)
 {
diff --git a/include/linux/pci_liveupdate.h b/include/linux/pci_liveupdate.h
new file mode 100644
index 000000000000..bb79348769b7
--- /dev/null
+++ b/include/linux/pci_liveupdate.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PCI Live Update support (Public/Driver API)
+ *
+ * Copyright (c) 2026, Google LLC.
+ * David Matlack <dmatlack@google.com>
+ */
+#ifndef LINUX_PCI_LIVEUPDATE_H
+#define LINUX_PCI_LIVEUPDATE_H
+
+#include <linux/kho/abi/pci.h>
+#include <linux/liveupdate.h>
+#include <linux/spinlock_types.h>
+#include <linux/types.h>
+
+/**
+ * struct pci_liveupdate - PCI Live Update state for a struct pci_dev
+ * @outgoing: State preserved for the next kernel.
+ * @incoming: State preserved by the previous kernel.
+ * @was_incoming: True if this struct pci_dev was incoming-preserved when it was
+ *                set up, i.e. it was matched to state preserved by the previous
+ *                kernel. Unlike @incoming, this is never cleared, so it stays
+ *                true after the device finishes participating in Live Update.
+ * @frozen: True if the outgoing preservation status of this device is frozen
+ *          and thus cannot be changed.
+ */
+struct pci_liveupdate {
+	struct pci_dev_ser *outgoing;
+	struct pci_dev_ser *incoming;
+	bool was_incoming;
+	bool frozen;
+};
+
+struct pci_dev;
+
+#ifdef CONFIG_PCI_LIVEUPDATE
+int pci_liveupdate_register_flb(struct liveupdate_file_handler *fh);
+void pci_liveupdate_unregister_flb(struct liveupdate_file_handler *fh);
+int pci_liveupdate_preserve(struct pci_dev *dev);
+void pci_liveupdate_unpreserve(struct pci_dev *dev);
+void pci_liveupdate_finish(struct pci_dev *dev);
+bool pci_liveupdate_is_incoming(struct pci_dev *dev);
+#else
+static inline int pci_liveupdate_register_flb(struct liveupdate_file_handler *fh)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void pci_liveupdate_unregister_flb(struct liveupdate_file_handler *fh)
+{
+}
+
+static inline int pci_liveupdate_preserve(struct pci_dev *dev)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void pci_liveupdate_unpreserve(struct pci_dev *dev)
+{
+}
+
+static inline void pci_liveupdate_finish(struct pci_dev *dev)
+{
+}
+
+static inline bool pci_liveupdate_is_incoming(struct pci_dev *dev)
+{
+	return false;
+}
+#endif
+
+#endif /* LINUX_PCI_LIVEUPDATE_H */