Changelog: v9: Added review-bys and addressed comments from Mike Rapoport and Pratyush Yadav. Dropped patch that moves abort/finalize to public header per Mike's request. Added patch from Zhu Yanjun to output errors by name.
This series appliyes against akpm's mm-unstable branch.
This series refactors the KHO framework to better support in-kernel users like the upcoming LUO. The current design, which relies on a notifier chain and debugfs for control, is too restrictive for direct programmatic use.
The core of this rework is the removal of the notifier chain in favor of a direct registration API. This decouples clients from the shutdown-time finalization sequence, allowing them to manage their preserved state more flexibly and at any time.
In support of this new model, this series also: - Makes the debugfs interface optional. - Introduces APIs to unpreserve memory and fixes a bug in the abort path where client state was being incorrectly discarded. Note that this is an interim step, as a more comprehensive fix is planned as part of the stateless KHO work [1]. - Moves all KHO code into a new kernel/liveupdate/ directory to consolidate live update components.
[1] https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com
Mike Rapoport (Microsoft) (1): kho: drop notifiers
Pasha Tatashin (7): kho: make debugfs interface optional kho: add interfaces to unpreserve folios, page ranges, and vmalloc memblock: Unpreserve memory in case of error test_kho: Unpreserve memory in case of error kho: don't unpreserve memory during abort liveupdate: kho: move to kernel/liveupdate MAINTAINERS: update KHO maintainers
Zhu Yanjun (1): liveupdate: kho: Use %pe format specifier for error pointer printing
Documentation/core-api/kho/concepts.rst | 2 +- MAINTAINERS | 4 +- include/linux/kexec_handover.h | 46 +- init/Kconfig | 2 + kernel/Kconfig.kexec | 24 - kernel/Makefile | 3 +- kernel/kexec_handover_internal.h | 16 - kernel/liveupdate/Kconfig | 39 ++ kernel/liveupdate/Makefile | 5 + kernel/{ => liveupdate}/kexec_handover.c | 532 +++++++----------- .../{ => liveupdate}/kexec_handover_debug.c | 0 kernel/liveupdate/kexec_handover_debugfs.c | 221 ++++++++ kernel/liveupdate/kexec_handover_internal.h | 56 ++ lib/test_kho.c | 128 +++-- mm/memblock.c | 93 +-- tools/testing/selftests/kho/vmtest.sh | 1 + 16 files changed, 690 insertions(+), 482 deletions(-) delete mode 100644 kernel/kexec_handover_internal.h create mode 100644 kernel/liveupdate/Kconfig create mode 100644 kernel/liveupdate/Makefile rename kernel/{ => liveupdate}/kexec_handover.c (80%) rename kernel/{ => liveupdate}/kexec_handover_debug.c (100%) create mode 100644 kernel/liveupdate/kexec_handover_debugfs.c create mode 100644 kernel/liveupdate/kexec_handover_internal.h
base-commit: 9ef7b034116354ee75502d1849280a4d2ff98a7c
Currently, KHO is controlled via debugfs interface, but once LUO is introduced, it can control KHO, and the debug interface becomes optional.
Add a separate config CONFIG_KEXEC_HANDOVER_DEBUGFS that enables the debugfs interface, and allows to inspect the tree.
Move all debugfs related code to a new file to keep the .c files clear of ifdefs.
Co-developed-by: Mike Rapoport (Microsoft) rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Pratyush Yadav pratyush@kernel.org --- MAINTAINERS | 2 +- kernel/Kconfig.kexec | 12 +- kernel/Makefile | 1 + kernel/kexec_handover.c | 273 +++++--------------------- kernel/kexec_handover_debugfs.c | 216 ++++++++++++++++++++ kernel/kexec_handover_internal.h | 39 ++++ tools/testing/selftests/kho/vmtest.sh | 1 + 7 files changed, 320 insertions(+), 224 deletions(-) create mode 100644 kernel/kexec_handover_debugfs.c
diff --git a/MAINTAINERS b/MAINTAINERS index 2628431dcdfe..bdd0a1260421 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13795,7 +13795,7 @@ S: Maintained F: Documentation/admin-guide/mm/kho.rst F: Documentation/core-api/kho/* F: include/linux/kexec_handover.h -F: kernel/kexec_handover.c +F: kernel/kexec_handover* F: tools/testing/selftests/kho/
KEYS-ENCRYPTED diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec index 54e581072617..cc6743137946 100644 --- a/kernel/Kconfig.kexec +++ b/kernel/Kconfig.kexec @@ -100,7 +100,6 @@ config KEXEC_HANDOVER depends on !DEFERRED_STRUCT_PAGE_INIT select MEMBLOCK_KHO_SCRATCH select KEXEC_FILE - select DEBUG_FS select LIBFDT select CMA help @@ -118,6 +117,17 @@ config KEXEC_HANDOVER_DEBUG scenarios and the extra code might be adding overhead it is only optionally enabled.
+config KEXEC_HANDOVER_DEBUGFS + bool "kexec handover debugfs interface" + default KEXEC_HANDOVER + depends on KEXEC_HANDOVER + select DEBUG_FS + help + Allow to control kexec handover device tree via debugfs + interface, i.e. finalize the state or aborting the finalization. + Also, enables inspecting the KHO fdt trees with the debugfs binary + blobs. + config CRASH_DUMP bool "kernel crash dumps" default ARCH_DEFAULT_CRASH_DUMP diff --git a/kernel/Makefile b/kernel/Makefile index 9fe722305c9b..2cf7909a74e5 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -84,6 +84,7 @@ obj-$(CONFIG_KEXEC_FILE) += kexec_file.o obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o obj-$(CONFIG_KEXEC_HANDOVER) += kexec_handover.o obj-$(CONFIG_KEXEC_HANDOVER_DEBUG) += kexec_handover_debug.o +obj-$(CONFIG_KEXEC_HANDOVER_DEBUGFS) += kexec_handover_debugfs.o obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o obj-$(CONFIG_COMPAT) += compat.o obj-$(CONFIG_CGROUPS) += cgroup/ diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index de4466b47455..da071277d85e 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -11,7 +11,6 @@ #include <linux/cleanup.h> #include <linux/cma.h> #include <linux/count_zeros.h> -#include <linux/debugfs.h> #include <linux/kexec.h> #include <linux/kexec_handover.h> #include <linux/libfdt.h> @@ -30,6 +29,7 @@ */ #include "../mm/internal.h" #include "kexec_internal.h" +#include "kexec_handover_internal.h"
#define KHO_FDT_COMPATIBLE "kho-v1" #define PROP_PRESERVED_MEMORY_MAP "preserved-memory-map" @@ -105,8 +105,6 @@ struct khoser_mem_chunk;
struct kho_serialization { struct page *fdt; - struct list_head fdt_list; - struct dentry *sub_fdt_dir; struct kho_mem_track track; /* First chunk of serialized preserved memory map */ struct khoser_mem_chunk *preserved_mem_map; @@ -114,20 +112,16 @@ struct kho_serialization {
struct kho_out { struct blocking_notifier_head chain_head; - - struct dentry *dir; - struct mutex lock; /* protects KHO FDT finalization */ - struct kho_serialization ser; bool finalized; + struct kho_debugfs dbg; };
static struct kho_out kho_out = { .chain_head = BLOCKING_NOTIFIER_INIT(kho_out.chain_head), .lock = __MUTEX_INITIALIZER(kho_out.lock), .ser = { - .fdt_list = LIST_HEAD_INIT(kho_out.ser.fdt_list), .track = { .orders = XARRAY_INIT(kho_out.ser.track.orders, 0), }, @@ -477,8 +471,8 @@ static void __init kho_mem_deserialize(const void *fdt) * area for early allocations that happen before page allocator is * initialized. */ -static struct kho_scratch *kho_scratch; -static unsigned int kho_scratch_cnt; +struct kho_scratch *kho_scratch; +unsigned int kho_scratch_cnt;
/* * The scratch areas are scaled by default as percent of memory allocated from @@ -674,37 +668,6 @@ static void __init kho_reserve_scratch(void) kho_enable = false; }
-struct fdt_debugfs { - struct list_head list; - struct debugfs_blob_wrapper wrapper; - struct dentry *file; -}; - -static int kho_debugfs_fdt_add(struct list_head *list, struct dentry *dir, - const char *name, const void *fdt) -{ - struct fdt_debugfs *f; - struct dentry *file; - - f = kmalloc(sizeof(*f), GFP_KERNEL); - if (!f) - return -ENOMEM; - - f->wrapper.data = (void *)fdt; - f->wrapper.size = fdt_totalsize(fdt); - - file = debugfs_create_blob(name, 0400, dir, &f->wrapper); - if (IS_ERR(file)) { - kfree(f); - return PTR_ERR(file); - } - - f->file = file; - list_add(&f->list, list); - - return 0; -} - /** * kho_add_subtree - record the physical address of a sub FDT in KHO root tree. * @ser: serialization control object passed by KHO notifiers. @@ -716,7 +679,8 @@ static int kho_debugfs_fdt_add(struct list_head *list, struct dentry *dir, * by KHO for the new kernel to retrieve it after kexec. * * A debugfs blob entry is also created at - * ``/sys/kernel/debug/kho/out/sub_fdts/@name``. + * ``/sys/kernel/debug/kho/out/sub_fdts/@name`` when kernel is configured with + * CONFIG_KEXEC_HANDOVER_DEBUGFS * * Return: 0 on success, error code on failure */ @@ -733,7 +697,7 @@ int kho_add_subtree(struct kho_serialization *ser, const char *name, void *fdt) if (err) return err;
- return kho_debugfs_fdt_add(&ser->fdt_list, ser->sub_fdt_dir, name, fdt); + return kho_debugfs_fdt_add(&kho_out.dbg, name, fdt, false); } EXPORT_SYMBOL_GPL(kho_add_subtree);
@@ -1064,30 +1028,7 @@ void *kho_restore_vmalloc(const struct kho_vmalloc *preservation) } EXPORT_SYMBOL_GPL(kho_restore_vmalloc);
-/* Handling for debug/kho/out */ - -static struct dentry *debugfs_root; - -static int kho_out_update_debugfs_fdt(void) -{ - int err = 0; - struct fdt_debugfs *ff, *tmp; - - if (kho_out.finalized) { - err = kho_debugfs_fdt_add(&kho_out.ser.fdt_list, kho_out.dir, - "fdt", page_to_virt(kho_out.ser.fdt)); - } else { - list_for_each_entry_safe(ff, tmp, &kho_out.ser.fdt_list, list) { - debugfs_remove(ff->file); - list_del(&ff->list); - kfree(ff); - } - } - - return err; -} - -static int kho_abort(void) +static int __kho_abort(void) { int err; unsigned long order; @@ -1120,7 +1061,28 @@ static int kho_abort(void) return err; }
-static int kho_finalize(void) +int kho_abort(void) +{ + int ret = 0; + + if (!kho_enable) + return -EOPNOTSUPP; + + guard(mutex)(&kho_out.lock); + if (!kho_out.finalized) + return -ENOENT; + + ret = __kho_abort(); + if (ret) + return ret; + + kho_out.finalized = false; + kho_debugfs_cleanup(&kho_out.dbg); + + return 0; +} + +static int __kho_finalize(void) { int err = 0; u64 *preserved_mem_map; @@ -1163,118 +1125,46 @@ static int kho_finalize(void) abort: if (err) { pr_err("Failed to convert KHO state tree: %d\n", err); - kho_abort(); + __kho_abort(); }
return err; }
-static int kho_out_finalize_get(void *data, u64 *val) +int kho_finalize(void) { - mutex_lock(&kho_out.lock); - *val = kho_out.finalized; - mutex_unlock(&kho_out.lock); - - return 0; -} - -static int kho_out_finalize_set(void *data, u64 _val) -{ - int ret = 0; - bool val = !!_val; - - mutex_lock(&kho_out.lock); + int ret;
- if (val == kho_out.finalized) { - if (kho_out.finalized) - ret = -EEXIST; - else - ret = -ENOENT; - goto unlock; - } + if (!kho_enable) + return -EOPNOTSUPP;
- if (val) - ret = kho_finalize(); - else - ret = kho_abort(); + guard(mutex)(&kho_out.lock); + if (kho_out.finalized) + return -EEXIST;
+ ret = __kho_finalize(); if (ret) - goto unlock; - - kho_out.finalized = val; - ret = kho_out_update_debugfs_fdt(); - -unlock: - mutex_unlock(&kho_out.lock); - return ret; -} - -DEFINE_DEBUGFS_ATTRIBUTE(fops_kho_out_finalize, kho_out_finalize_get, - kho_out_finalize_set, "%llu\n"); - -static int scratch_phys_show(struct seq_file *m, void *v) -{ - for (int i = 0; i < kho_scratch_cnt; i++) - seq_printf(m, "0x%llx\n", kho_scratch[i].addr); - - return 0; -} -DEFINE_SHOW_ATTRIBUTE(scratch_phys); + return ret;
-static int scratch_len_show(struct seq_file *m, void *v) -{ - for (int i = 0; i < kho_scratch_cnt; i++) - seq_printf(m, "0x%llx\n", kho_scratch[i].size); + kho_out.finalized = true;
- return 0; + return kho_debugfs_fdt_add(&kho_out.dbg, "fdt", + page_to_virt(kho_out.ser.fdt), true); } -DEFINE_SHOW_ATTRIBUTE(scratch_len);
-static __init int kho_out_debugfs_init(void) +bool kho_finalized(void) { - struct dentry *dir, *f, *sub_fdt_dir; - - dir = debugfs_create_dir("out", debugfs_root); - if (IS_ERR(dir)) - return -ENOMEM; - - sub_fdt_dir = debugfs_create_dir("sub_fdts", dir); - if (IS_ERR(sub_fdt_dir)) - goto err_rmdir; - - f = debugfs_create_file("scratch_phys", 0400, dir, NULL, - &scratch_phys_fops); - if (IS_ERR(f)) - goto err_rmdir; - - f = debugfs_create_file("scratch_len", 0400, dir, NULL, - &scratch_len_fops); - if (IS_ERR(f)) - goto err_rmdir; - - f = debugfs_create_file("finalize", 0600, dir, NULL, - &fops_kho_out_finalize); - if (IS_ERR(f)) - goto err_rmdir; - - kho_out.dir = dir; - kho_out.ser.sub_fdt_dir = sub_fdt_dir; - return 0; - -err_rmdir: - debugfs_remove_recursive(dir); - return -ENOENT; + guard(mutex)(&kho_out.lock); + return kho_out.finalized; }
struct kho_in { - struct dentry *dir; phys_addr_t fdt_phys; phys_addr_t scratch_phys; - struct list_head fdt_list; + struct kho_debugfs dbg; };
static struct kho_in kho_in = { - .fdt_list = LIST_HEAD_INIT(kho_in.fdt_list), };
static const void *kho_get_fdt(void) @@ -1338,56 +1228,6 @@ int kho_retrieve_subtree(const char *name, phys_addr_t *phys) } EXPORT_SYMBOL_GPL(kho_retrieve_subtree);
-/* Handling for debugfs/kho/in */ - -static __init int kho_in_debugfs_init(const void *fdt) -{ - struct dentry *sub_fdt_dir; - int err, child; - - kho_in.dir = debugfs_create_dir("in", debugfs_root); - if (IS_ERR(kho_in.dir)) - return PTR_ERR(kho_in.dir); - - sub_fdt_dir = debugfs_create_dir("sub_fdts", kho_in.dir); - if (IS_ERR(sub_fdt_dir)) { - err = PTR_ERR(sub_fdt_dir); - goto err_rmdir; - } - - err = kho_debugfs_fdt_add(&kho_in.fdt_list, kho_in.dir, "fdt", fdt); - if (err) - goto err_rmdir; - - fdt_for_each_subnode(child, fdt, 0) { - int len = 0; - const char *name = fdt_get_name(fdt, child, NULL); - const u64 *fdt_phys; - - fdt_phys = fdt_getprop(fdt, child, "fdt", &len); - if (!fdt_phys) - continue; - if (len != sizeof(*fdt_phys)) { - pr_warn("node `%s`'s prop `fdt` has invalid length: %d\n", - name, len); - continue; - } - err = kho_debugfs_fdt_add(&kho_in.fdt_list, sub_fdt_dir, name, - phys_to_virt(*fdt_phys)); - if (err) { - pr_warn("failed to add fdt `%s` to debugfs: %d\n", name, - err); - continue; - } - } - - return 0; - -err_rmdir: - debugfs_remove_recursive(kho_in.dir); - return err; -} - static __init int kho_init(void) { int err = 0; @@ -1402,27 +1242,16 @@ static __init int kho_init(void) goto err_free_scratch; }
- debugfs_root = debugfs_create_dir("kho", NULL); - if (IS_ERR(debugfs_root)) { - err = -ENOENT; + err = kho_debugfs_init(); + if (err) goto err_free_fdt; - }
- err = kho_out_debugfs_init(); + err = kho_out_debugfs_init(&kho_out.dbg); if (err) goto err_free_fdt;
if (fdt) { - err = kho_in_debugfs_init(fdt); - /* - * Failure to create /sys/kernel/debug/kho/in does not prevent - * reviving state from KHO and setting up KHO for the next - * kexec. - */ - if (err) - pr_err("failed exposing handover FDT in debugfs: %d\n", - err); - + kho_in_debugfs_init(&kho_in.dbg, fdt); return 0; }
diff --git a/kernel/kexec_handover_debugfs.c b/kernel/kexec_handover_debugfs.c new file mode 100644 index 000000000000..a91b279f1b23 --- /dev/null +++ b/kernel/kexec_handover_debugfs.c @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kexec_handover_debugfs.c - kexec handover debugfs interfaces + * Copyright (C) 2023 Alexander Graf graf@amazon.com + * Copyright (C) 2025 Microsoft Corporation, Mike Rapoport rppt@kernel.org + * Copyright (C) 2025 Google LLC, Changyuan Lyu changyuanl@google.com + * Copyright (C) 2025 Google LLC, Pasha Tatashin pasha.tatashin@soleen.com + */ + +#define pr_fmt(fmt) "KHO: " fmt + +#include <linux/init.h> +#include <linux/io.h> +#include <linux/libfdt.h> +#include <linux/mm.h> +#include "kexec_handover_internal.h" + +static struct dentry *debugfs_root; + +struct fdt_debugfs { + struct list_head list; + struct debugfs_blob_wrapper wrapper; + struct dentry *file; +}; + +static int __kho_debugfs_fdt_add(struct list_head *list, struct dentry *dir, + const char *name, const void *fdt) +{ + struct fdt_debugfs *f; + struct dentry *file; + + f = kmalloc(sizeof(*f), GFP_KERNEL); + if (!f) + return -ENOMEM; + + f->wrapper.data = (void *)fdt; + f->wrapper.size = fdt_totalsize(fdt); + + file = debugfs_create_blob(name, 0400, dir, &f->wrapper); + if (IS_ERR(file)) { + kfree(f); + return PTR_ERR(file); + } + + f->file = file; + list_add(&f->list, list); + + return 0; +} + +int kho_debugfs_fdt_add(struct kho_debugfs *dbg, const char *name, + const void *fdt, bool root) +{ + struct dentry *dir; + + if (root) + dir = dbg->dir; + else + dir = dbg->sub_fdt_dir; + + return __kho_debugfs_fdt_add(&dbg->fdt_list, dir, name, fdt); +} + +void kho_debugfs_cleanup(struct kho_debugfs *dbg) +{ + struct fdt_debugfs *ff, *tmp; + + list_for_each_entry_safe(ff, tmp, &dbg->fdt_list, list) { + debugfs_remove(ff->file); + list_del(&ff->list); + kfree(ff); + } +} + +static int kho_out_finalize_get(void *data, u64 *val) +{ + *val = kho_finalized(); + + return 0; +} + +static int kho_out_finalize_set(void *data, u64 val) +{ + if (val) + return kho_finalize(); + else + return kho_abort(); +} + +DEFINE_DEBUGFS_ATTRIBUTE(kho_out_finalize_fops, kho_out_finalize_get, + kho_out_finalize_set, "%llu\n"); + +static int scratch_phys_show(struct seq_file *m, void *v) +{ + for (int i = 0; i < kho_scratch_cnt; i++) + seq_printf(m, "0x%llx\n", kho_scratch[i].addr); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(scratch_phys); + +static int scratch_len_show(struct seq_file *m, void *v) +{ + for (int i = 0; i < kho_scratch_cnt; i++) + seq_printf(m, "0x%llx\n", kho_scratch[i].size); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(scratch_len); + +__init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt) +{ + struct dentry *dir, *sub_fdt_dir; + int err, child; + + INIT_LIST_HEAD(&dbg->fdt_list); + + dir = debugfs_create_dir("in", debugfs_root); + if (IS_ERR(dir)) { + err = PTR_ERR(dir); + goto err_out; + } + + sub_fdt_dir = debugfs_create_dir("sub_fdts", dir); + if (IS_ERR(sub_fdt_dir)) { + err = PTR_ERR(sub_fdt_dir); + goto err_rmdir; + } + + err = __kho_debugfs_fdt_add(&dbg->fdt_list, dir, "fdt", fdt); + if (err) + goto err_rmdir; + + fdt_for_each_subnode(child, fdt, 0) { + int len = 0; + const char *name = fdt_get_name(fdt, child, NULL); + const u64 *fdt_phys; + + fdt_phys = fdt_getprop(fdt, child, "fdt", &len); + if (!fdt_phys) + continue; + if (len != sizeof(*fdt_phys)) { + pr_warn("node %s prop fdt has invalid length: %d\n", + name, len); + continue; + } + err = __kho_debugfs_fdt_add(&dbg->fdt_list, sub_fdt_dir, name, + phys_to_virt(*fdt_phys)); + if (err) { + pr_warn("failed to add fdt %s to debugfs: %d\n", name, + err); + continue; + } + } + + dbg->dir = dir; + dbg->sub_fdt_dir = sub_fdt_dir; + + return; +err_rmdir: + debugfs_remove_recursive(dir); +err_out: + /* + * Failure to create /sys/kernel/debug/kho/in does not prevent + * reviving state from KHO and setting up KHO for the next + * kexec. + */ + if (err) + pr_err("failed exposing handover FDT in debugfs: %d\n", err); +} + +__init int kho_out_debugfs_init(struct kho_debugfs *dbg) +{ + struct dentry *dir, *f, *sub_fdt_dir; + + INIT_LIST_HEAD(&dbg->fdt_list); + + dir = debugfs_create_dir("out", debugfs_root); + if (IS_ERR(dir)) + return -ENOMEM; + + sub_fdt_dir = debugfs_create_dir("sub_fdts", dir); + if (IS_ERR(sub_fdt_dir)) + goto err_rmdir; + + f = debugfs_create_file("scratch_phys", 0400, dir, NULL, + &scratch_phys_fops); + if (IS_ERR(f)) + goto err_rmdir; + + f = debugfs_create_file("scratch_len", 0400, dir, NULL, + &scratch_len_fops); + if (IS_ERR(f)) + goto err_rmdir; + + f = debugfs_create_file("finalize", 0600, dir, NULL, + &kho_out_finalize_fops); + if (IS_ERR(f)) + goto err_rmdir; + + dbg->dir = dir; + dbg->sub_fdt_dir = sub_fdt_dir; + return 0; + +err_rmdir: + debugfs_remove_recursive(dir); + return -ENOENT; +} + +__init int kho_debugfs_init(void) +{ + debugfs_root = debugfs_create_dir("kho", NULL); + if (IS_ERR(debugfs_root)) + return -ENOENT; + return 0; +} diff --git a/kernel/kexec_handover_internal.h b/kernel/kexec_handover_internal.h index 05e9720ba7b9..217b8b25a542 100644 --- a/kernel/kexec_handover_internal.h +++ b/kernel/kexec_handover_internal.h @@ -2,8 +2,47 @@ #ifndef LINUX_KEXEC_HANDOVER_INTERNAL_H #define LINUX_KEXEC_HANDOVER_INTERNAL_H
+#include <linux/kexec_handover.h> +#include <linux/list.h> #include <linux/types.h>
+#ifdef CONFIG_KEXEC_HANDOVER_DEBUGFS +#include <linux/debugfs.h> + +struct kho_debugfs { + struct dentry *dir; + struct dentry *sub_fdt_dir; + struct list_head fdt_list; +}; + +#else +struct kho_debugfs {}; +#endif + +extern struct kho_scratch *kho_scratch; +extern unsigned int kho_scratch_cnt; + +bool kho_finalized(void); +int kho_finalize(void); +int kho_abort(void); + +#ifdef CONFIG_KEXEC_HANDOVER_DEBUGFS +int kho_debugfs_init(void); +void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt); +int kho_out_debugfs_init(struct kho_debugfs *dbg); +int kho_debugfs_fdt_add(struct kho_debugfs *dbg, const char *name, + const void *fdt, bool root); +void kho_debugfs_cleanup(struct kho_debugfs *dbg); +#else +static inline int kho_debugfs_init(void) { return 0; } +static inline void kho_in_debugfs_init(struct kho_debugfs *dbg, + const void *fdt) { } +static inline int kho_out_debugfs_init(struct kho_debugfs *dbg) { return 0; } +static inline int kho_debugfs_fdt_add(struct kho_debugfs *dbg, const char *name, + const void *fdt, bool root) { return 0; } +static inline void kho_debugfs_cleanup(struct kho_debugfs *dbg) {} +#endif /* CONFIG_KEXEC_HANDOVER_DEBUGFS */ + #ifdef CONFIG_KEXEC_HANDOVER_DEBUG bool kho_scratch_overlap(phys_addr_t phys, size_t size); #else diff --git a/tools/testing/selftests/kho/vmtest.sh b/tools/testing/selftests/kho/vmtest.sh index 3f6c17166846..49fdac8e8b15 100755 --- a/tools/testing/selftests/kho/vmtest.sh +++ b/tools/testing/selftests/kho/vmtest.sh @@ -59,6 +59,7 @@ function build_kernel() { tee "$kconfig" > "$kho_config" <<EOF CONFIG_BLK_DEV_INITRD=y CONFIG_KEXEC_HANDOVER=y +CONFIG_KEXEC_HANDOVER_DEBUGFS=y CONFIG_TEST_KEXEC_HANDOVER=y CONFIG_DEBUG_KERNEL=y CONFIG_DEBUG_VM=y
From: "Mike Rapoport (Microsoft)" rppt@kernel.org
The KHO framework uses a notifier chain as the mechanism for clients to participate in the finalization process. While this works for a single, central state machine, it is too restrictive for kernel-internal components like pstore/reserve_mem or IMA. These components need a simpler, direct way to register their state for preservation (e.g., during their initcall) without being part of a complex, shutdown-time notifier sequence. The notifier model forces all participants into a single finalization flow and makes direct preservation from an arbitrary context difficult. This patch refactors the client participation model by removing the notifier chain and introducing a direct API for managing FDT subtrees.
The core kho_finalize() and kho_abort() state machine remains, but clients now register their data with KHO beforehand.
Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org Co-developed-by: Pasha Tatashin pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com --- include/linux/kexec_handover.h | 28 +----- kernel/kexec_handover.c | 166 +++++++++++++++++-------------- kernel/kexec_handover_debugfs.c | 17 ++-- kernel/kexec_handover_internal.h | 5 +- lib/test_kho.c | 35 +------ mm/memblock.c | 62 +++--------- 6 files changed, 125 insertions(+), 188 deletions(-)
diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index 25042c1d8d54..0d860d793b66 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -10,14 +10,7 @@ struct kho_scratch { phys_addr_t size; };
-/* KHO Notifier index */ -enum kho_event { - KEXEC_KHO_FINALIZE = 0, - KEXEC_KHO_ABORT = 1, -}; - struct folio; -struct notifier_block; struct page;
#define DECLARE_KHOSER_PTR(name, type) \ @@ -37,8 +30,6 @@ struct page; (typeof((s).ptr))((s).phys ? phys_to_virt((s).phys) : NULL); \ })
-struct kho_serialization; - struct kho_vmalloc_chunk; struct kho_vmalloc { DECLARE_KHOSER_PTR(first, struct kho_vmalloc_chunk *); @@ -57,12 +48,10 @@ int kho_preserve_vmalloc(void *ptr, struct kho_vmalloc *preservation); struct folio *kho_restore_folio(phys_addr_t phys); struct page *kho_restore_pages(phys_addr_t phys, unsigned int nr_pages); void *kho_restore_vmalloc(const struct kho_vmalloc *preservation); -int kho_add_subtree(struct kho_serialization *ser, const char *name, void *fdt); +int kho_add_subtree(const char *name, void *fdt); +void kho_remove_subtree(void *fdt); int kho_retrieve_subtree(const char *name, phys_addr_t *phys);
-int register_kho_notifier(struct notifier_block *nb); -int unregister_kho_notifier(struct notifier_block *nb); - void kho_memory_init(void);
void kho_populate(phys_addr_t fdt_phys, u64 fdt_len, phys_addr_t scratch_phys, @@ -110,23 +99,16 @@ static inline void *kho_restore_vmalloc(const struct kho_vmalloc *preservation) return NULL; }
-static inline int kho_add_subtree(struct kho_serialization *ser, - const char *name, void *fdt) +static inline int kho_add_subtree(const char *name, void *fdt) { return -EOPNOTSUPP; }
-static inline int kho_retrieve_subtree(const char *name, phys_addr_t *phys) +static inline void kho_remove_subtree(void *fdt) { - return -EOPNOTSUPP; }
-static inline int register_kho_notifier(struct notifier_block *nb) -{ - return -EOPNOTSUPP; -} - -static inline int unregister_kho_notifier(struct notifier_block *nb) +static inline int kho_retrieve_subtree(const char *name, phys_addr_t *phys) { return -EOPNOTSUPP; } diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index da071277d85e..82137eba1474 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -16,7 +16,6 @@ #include <linux/libfdt.h> #include <linux/list.h> #include <linux/memblock.h> -#include <linux/notifier.h> #include <linux/page-isolation.h> #include <linux/vmalloc.h>
@@ -103,29 +102,34 @@ struct kho_mem_track {
struct khoser_mem_chunk;
-struct kho_serialization { - struct page *fdt; - struct kho_mem_track track; - /* First chunk of serialized preserved memory map */ - struct khoser_mem_chunk *preserved_mem_map; +struct kho_sub_fdt { + struct list_head l; + const char *name; + void *fdt; };
struct kho_out { - struct blocking_notifier_head chain_head; - struct mutex lock; /* protects KHO FDT finalization */ - struct kho_serialization ser; + void *fdt; bool finalized; + struct mutex lock; /* protects KHO FDT finalization */ + + struct list_head sub_fdts; + struct mutex fdts_lock; + + struct kho_mem_track track; + /* First chunk of serialized preserved memory map */ + struct khoser_mem_chunk *preserved_mem_map; + struct kho_debugfs dbg; };
static struct kho_out kho_out = { - .chain_head = BLOCKING_NOTIFIER_INIT(kho_out.chain_head), .lock = __MUTEX_INITIALIZER(kho_out.lock), - .ser = { - .track = { - .orders = XARRAY_INIT(kho_out.ser.track.orders, 0), - }, + .track = { + .orders = XARRAY_INIT(kho_out.track.orders, 0), }, + .sub_fdts = LIST_HEAD_INIT(kho_out.sub_fdts), + .fdts_lock = __MUTEX_INITIALIZER(kho_out.fdts_lock), .finalized = false, };
@@ -369,7 +373,7 @@ static void kho_mem_ser_free(struct khoser_mem_chunk *first_chunk) } }
-static int kho_mem_serialize(struct kho_serialization *ser) +static int kho_mem_serialize(struct kho_out *kho_out) { struct khoser_mem_chunk *first_chunk = NULL; struct khoser_mem_chunk *chunk = NULL; @@ -377,7 +381,7 @@ static int kho_mem_serialize(struct kho_serialization *ser) unsigned long order; int err = -ENOMEM;
- xa_for_each(&ser->track.orders, order, physxa) { + xa_for_each(&kho_out->track.orders, order, physxa) { struct kho_mem_phys_bits *bits; unsigned long phys;
@@ -409,7 +413,7 @@ static int kho_mem_serialize(struct kho_serialization *ser) } }
- ser->preserved_mem_map = first_chunk; + kho_out->preserved_mem_map = first_chunk;
return 0;
@@ -670,7 +674,6 @@ static void __init kho_reserve_scratch(void)
/** * kho_add_subtree - record the physical address of a sub FDT in KHO root tree. - * @ser: serialization control object passed by KHO notifiers. * @name: name of the sub tree. * @fdt: the sub tree blob. * @@ -684,34 +687,41 @@ static void __init kho_reserve_scratch(void) * * Return: 0 on success, error code on failure */ -int kho_add_subtree(struct kho_serialization *ser, const char *name, void *fdt) +int kho_add_subtree(const char *name, void *fdt) { - int err = 0; - u64 phys = (u64)virt_to_phys(fdt); - void *root = page_to_virt(ser->fdt); + struct kho_sub_fdt *sub_fdt;
- err |= fdt_begin_node(root, name); - err |= fdt_property(root, PROP_SUB_FDT, &phys, sizeof(phys)); - err |= fdt_end_node(root); + sub_fdt = kmalloc(sizeof(*sub_fdt), GFP_KERNEL); + if (!sub_fdt) + return -ENOMEM;
- if (err) - return err; + INIT_LIST_HEAD(&sub_fdt->l); + sub_fdt->name = name; + sub_fdt->fdt = fdt;
- return kho_debugfs_fdt_add(&kho_out.dbg, name, fdt, false); -} -EXPORT_SYMBOL_GPL(kho_add_subtree); + guard(mutex)(&kho_out.fdts_lock); + list_add_tail(&sub_fdt->l, &kho_out.sub_fdts); + WARN_ON_ONCE(kho_debugfs_fdt_add(&kho_out.dbg, name, fdt, false));
-int register_kho_notifier(struct notifier_block *nb) -{ - return blocking_notifier_chain_register(&kho_out.chain_head, nb); + return 0; } -EXPORT_SYMBOL_GPL(register_kho_notifier); +EXPORT_SYMBOL_GPL(kho_add_subtree);
-int unregister_kho_notifier(struct notifier_block *nb) +void kho_remove_subtree(void *fdt) { - return blocking_notifier_chain_unregister(&kho_out.chain_head, nb); + struct kho_sub_fdt *sub_fdt; + + guard(mutex)(&kho_out.fdts_lock); + list_for_each_entry(sub_fdt, &kho_out.sub_fdts, l) { + if (sub_fdt->fdt == fdt) { + list_del(&sub_fdt->l); + kfree(sub_fdt); + kho_debugfs_fdt_remove(&kho_out.dbg, fdt); + break; + } + } } -EXPORT_SYMBOL_GPL(unregister_kho_notifier); +EXPORT_SYMBOL_GPL(kho_remove_subtree);
/** * kho_preserve_folio - preserve a folio across kexec. @@ -726,7 +736,7 @@ int kho_preserve_folio(struct folio *folio) { const unsigned long pfn = folio_pfn(folio); const unsigned int order = folio_order(folio); - struct kho_mem_track *track = &kho_out.ser.track; + struct kho_mem_track *track = &kho_out.track;
if (WARN_ON(kho_scratch_overlap(pfn << PAGE_SHIFT, PAGE_SIZE << order))) return -EINVAL; @@ -747,7 +757,7 @@ EXPORT_SYMBOL_GPL(kho_preserve_folio); */ int kho_preserve_pages(struct page *page, unsigned int nr_pages) { - struct kho_mem_track *track = &kho_out.ser.track; + struct kho_mem_track *track = &kho_out.track; const unsigned long start_pfn = page_to_pfn(page); const unsigned long end_pfn = start_pfn + nr_pages; unsigned long pfn = start_pfn; @@ -848,7 +858,7 @@ static struct kho_vmalloc_chunk *new_vmalloc_chunk(struct kho_vmalloc_chunk *cur
static void kho_vmalloc_unpreserve_chunk(struct kho_vmalloc_chunk *chunk) { - struct kho_mem_track *track = &kho_out.ser.track; + struct kho_mem_track *track = &kho_out.track; unsigned long pfn = PHYS_PFN(virt_to_phys(chunk));
__kho_unpreserve(track, pfn, pfn + 1); @@ -1030,11 +1040,11 @@ EXPORT_SYMBOL_GPL(kho_restore_vmalloc);
static int __kho_abort(void) { - int err; + int err = 0; unsigned long order; struct kho_mem_phys *physxa;
- xa_for_each(&kho_out.ser.track.orders, order, physxa) { + xa_for_each(&kho_out.track.orders, order, physxa) { struct kho_mem_phys_bits *bits; unsigned long phys;
@@ -1044,17 +1054,13 @@ static int __kho_abort(void) xa_destroy(&physxa->phys_bits); kfree(physxa); } - xa_destroy(&kho_out.ser.track.orders); + xa_destroy(&kho_out.track.orders);
- if (kho_out.ser.preserved_mem_map) { - kho_mem_ser_free(kho_out.ser.preserved_mem_map); - kho_out.ser.preserved_mem_map = NULL; + if (kho_out.preserved_mem_map) { + kho_mem_ser_free(kho_out.preserved_mem_map); + kho_out.preserved_mem_map = NULL; }
- err = blocking_notifier_call_chain(&kho_out.chain_head, KEXEC_KHO_ABORT, - NULL); - err = notifier_to_errno(err); - if (err) pr_err("Failed to abort KHO finalization: %d\n", err);
@@ -1077,7 +1083,8 @@ int kho_abort(void) return ret;
kho_out.finalized = false; - kho_debugfs_cleanup(&kho_out.dbg); + + kho_debugfs_fdt_remove(&kho_out.dbg, kho_out.fdt);
return 0; } @@ -1086,41 +1093,46 @@ static int __kho_finalize(void) { int err = 0; u64 *preserved_mem_map; - void *fdt = page_to_virt(kho_out.ser.fdt); + void *root = kho_out.fdt; + struct kho_sub_fdt *fdt;
- err |= fdt_create(fdt, PAGE_SIZE); - err |= fdt_finish_reservemap(fdt); - err |= fdt_begin_node(fdt, ""); - err |= fdt_property_string(fdt, "compatible", KHO_FDT_COMPATIBLE); + err |= fdt_create(root, PAGE_SIZE); + err |= fdt_finish_reservemap(root); + err |= fdt_begin_node(root, ""); + err |= fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE); /** * Reserve the preserved-memory-map property in the root FDT, so * that all property definitions will precede subnodes created by * KHO callers. */ - err |= fdt_property_placeholder(fdt, PROP_PRESERVED_MEMORY_MAP, + err |= fdt_property_placeholder(root, PROP_PRESERVED_MEMORY_MAP, sizeof(*preserved_mem_map), (void **)&preserved_mem_map); if (err) goto abort;
- err = kho_preserve_folio(page_folio(kho_out.ser.fdt)); + err = kho_preserve_folio(virt_to_folio(kho_out.fdt)); if (err) goto abort;
- err = blocking_notifier_call_chain(&kho_out.chain_head, - KEXEC_KHO_FINALIZE, &kho_out.ser); - err = notifier_to_errno(err); + err = kho_mem_serialize(&kho_out); if (err) goto abort;
- err = kho_mem_serialize(&kho_out.ser); - if (err) - goto abort; + *preserved_mem_map = (u64)virt_to_phys(kho_out.preserved_mem_map); + + mutex_lock(&kho_out.fdts_lock); + list_for_each_entry(fdt, &kho_out.sub_fdts, l) { + phys_addr_t phys = virt_to_phys(fdt->fdt);
- *preserved_mem_map = (u64)virt_to_phys(kho_out.ser.preserved_mem_map); + err |= fdt_begin_node(root, fdt->name); + err |= fdt_property(root, PROP_SUB_FDT, &phys, sizeof(phys)); + err |= fdt_end_node(root); + } + mutex_unlock(&kho_out.fdts_lock);
- err |= fdt_end_node(fdt); - err |= fdt_finish(fdt); + err |= fdt_end_node(root); + err |= fdt_finish(root);
abort: if (err) { @@ -1148,8 +1160,10 @@ int kho_finalize(void)
kho_out.finalized = true;
- return kho_debugfs_fdt_add(&kho_out.dbg, "fdt", - page_to_virt(kho_out.ser.fdt), true); + WARN_ON_ONCE(kho_debugfs_fdt_add(&kho_out.dbg, "fdt", + kho_out.fdt, true)); + + return 0; }
bool kho_finalized(void) @@ -1232,15 +1246,17 @@ static __init int kho_init(void) { int err = 0; const void *fdt = kho_get_fdt(); + struct page *fdt_page;
if (!kho_enable) return 0;
- kho_out.ser.fdt = alloc_page(GFP_KERNEL); - if (!kho_out.ser.fdt) { + fdt_page = alloc_page(GFP_KERNEL); + if (!fdt_page) { err = -ENOMEM; goto err_free_scratch; } + kho_out.fdt = page_to_virt(fdt_page);
err = kho_debugfs_init(); if (err) @@ -1268,8 +1284,8 @@ static __init int kho_init(void) return 0;
err_free_fdt: - put_page(kho_out.ser.fdt); - kho_out.ser.fdt = NULL; + put_page(fdt_page); + kho_out.fdt = NULL; err_free_scratch: for (int i = 0; i < kho_scratch_cnt; i++) { void *start = __va(kho_scratch[i].addr); @@ -1280,7 +1296,7 @@ static __init int kho_init(void) kho_enable = false; return err; } -late_initcall(kho_init); +fs_initcall(kho_init);
static void __init kho_release_scratch(void) { @@ -1416,7 +1432,7 @@ int kho_fill_kimage(struct kimage *image) if (!kho_out.finalized) return 0;
- image->kho.fdt = page_to_phys(kho_out.ser.fdt); + image->kho.fdt = virt_to_phys(kho_out.fdt);
scratch_size = sizeof(*kho_scratch) * kho_scratch_cnt; scratch = (struct kexec_buf){ diff --git a/kernel/kexec_handover_debugfs.c b/kernel/kexec_handover_debugfs.c index a91b279f1b23..46e9e6c0791f 100644 --- a/kernel/kexec_handover_debugfs.c +++ b/kernel/kexec_handover_debugfs.c @@ -61,14 +61,17 @@ int kho_debugfs_fdt_add(struct kho_debugfs *dbg, const char *name, return __kho_debugfs_fdt_add(&dbg->fdt_list, dir, name, fdt); }
-void kho_debugfs_cleanup(struct kho_debugfs *dbg) +void kho_debugfs_fdt_remove(struct kho_debugfs *dbg, void *fdt) { - struct fdt_debugfs *ff, *tmp; - - list_for_each_entry_safe(ff, tmp, &dbg->fdt_list, list) { - debugfs_remove(ff->file); - list_del(&ff->list); - kfree(ff); + struct fdt_debugfs *ff; + + list_for_each_entry(ff, &dbg->fdt_list, list) { + if (ff->wrapper.data == fdt) { + debugfs_remove(ff->file); + list_del(&ff->list); + kfree(ff); + break; + } } }
diff --git a/kernel/kexec_handover_internal.h b/kernel/kexec_handover_internal.h index 217b8b25a542..52ed73659fe6 100644 --- a/kernel/kexec_handover_internal.h +++ b/kernel/kexec_handover_internal.h @@ -32,7 +32,7 @@ void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt); int kho_out_debugfs_init(struct kho_debugfs *dbg); int kho_debugfs_fdt_add(struct kho_debugfs *dbg, const char *name, const void *fdt, bool root); -void kho_debugfs_cleanup(struct kho_debugfs *dbg); +void kho_debugfs_fdt_remove(struct kho_debugfs *dbg, void *fdt); #else static inline int kho_debugfs_init(void) { return 0; } static inline void kho_in_debugfs_init(struct kho_debugfs *dbg, @@ -40,7 +40,8 @@ static inline void kho_in_debugfs_init(struct kho_debugfs *dbg, static inline int kho_out_debugfs_init(struct kho_debugfs *dbg) { return 0; } static inline int kho_debugfs_fdt_add(struct kho_debugfs *dbg, const char *name, const void *fdt, bool root) { return 0; } -static inline void kho_debugfs_cleanup(struct kho_debugfs *dbg) {} +static inline void kho_debugfs_fdt_remove(struct kho_debugfs *dbg, + void *fdt) { } #endif /* CONFIG_KEXEC_HANDOVER_DEBUGFS */
#ifdef CONFIG_KEXEC_HANDOVER_DEBUG diff --git a/lib/test_kho.c b/lib/test_kho.c index 60cd899ea745..9f7cfa6ac855 100644 --- a/lib/test_kho.c +++ b/lib/test_kho.c @@ -39,33 +39,6 @@ struct kho_test_state {
static struct kho_test_state kho_test_state;
-static int kho_test_notifier(struct notifier_block *self, unsigned long cmd, - void *v) -{ - struct kho_test_state *state = &kho_test_state; - struct kho_serialization *ser = v; - int err = 0; - - switch (cmd) { - case KEXEC_KHO_ABORT: - return NOTIFY_DONE; - case KEXEC_KHO_FINALIZE: - /* Handled below */ - break; - default: - return NOTIFY_BAD; - } - - err |= kho_preserve_folio(state->fdt); - err |= kho_add_subtree(ser, KHO_TEST_FDT, folio_address(state->fdt)); - - return err ? NOTIFY_BAD : NOTIFY_DONE; -} - -static struct notifier_block kho_test_nb = { - .notifier_call = kho_test_notifier, -}; - static int kho_test_save_data(struct kho_test_state *state, void *fdt) { phys_addr_t *folios_info __free(kvfree) = NULL; @@ -120,6 +93,7 @@ static int kho_test_prepare_fdt(struct kho_test_state *state)
fdt = folio_address(state->fdt);
+ err |= kho_preserve_folio(state->fdt); err |= fdt_create(fdt, fdt_size); err |= fdt_finish_reservemap(fdt);
@@ -131,6 +105,7 @@ static int kho_test_prepare_fdt(struct kho_test_state *state)
err |= fdt_finish(fdt);
+ err = kho_add_subtree(KHO_TEST_FDT, folio_address(state->fdt)); if (err) folio_put(state->fdt);
@@ -203,10 +178,6 @@ static int kho_test_save(void) if (err) goto err_free_folios;
- err = register_kho_notifier(&kho_test_nb); - if (err) - goto err_free_fdt; - return 0;
err_free_fdt: @@ -326,7 +297,7 @@ static void kho_test_cleanup(void)
static void __exit kho_test_exit(void) { - unregister_kho_notifier(&kho_test_nb); + kho_remove_subtree(folio_address(kho_test_state.fdt)); kho_test_cleanup(); } module_exit(kho_test_exit); diff --git a/mm/memblock.c b/mm/memblock.c index e23e16618e9b..e3bef9b35d63 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2444,53 +2444,18 @@ int reserve_mem_release_by_name(const char *name) #define MEMBLOCK_KHO_FDT "memblock" #define MEMBLOCK_KHO_NODE_COMPATIBLE "memblock-v1" #define RESERVE_MEM_KHO_NODE_COMPATIBLE "reserve-mem-v1" -static struct page *kho_fdt; - -static int reserve_mem_kho_finalize(struct kho_serialization *ser) -{ - int err = 0, i; - - for (i = 0; i < reserved_mem_count; i++) { - struct reserve_mem_table *map = &reserved_mem_table[i]; - struct page *page = phys_to_page(map->start); - unsigned int nr_pages = map->size >> PAGE_SHIFT; - - err |= kho_preserve_pages(page, nr_pages); - } - - err |= kho_preserve_folio(page_folio(kho_fdt)); - err |= kho_add_subtree(ser, MEMBLOCK_KHO_FDT, page_to_virt(kho_fdt)); - - return notifier_from_errno(err); -} - -static int reserve_mem_kho_notifier(struct notifier_block *self, - unsigned long cmd, void *v) -{ - switch (cmd) { - case KEXEC_KHO_FINALIZE: - return reserve_mem_kho_finalize((struct kho_serialization *)v); - case KEXEC_KHO_ABORT: - return NOTIFY_DONE; - default: - return NOTIFY_BAD; - } -} - -static struct notifier_block reserve_mem_kho_nb = { - .notifier_call = reserve_mem_kho_notifier, -};
static int __init prepare_kho_fdt(void) { int err = 0, i; + struct page *fdt_page; void *fdt;
- kho_fdt = alloc_page(GFP_KERNEL); - if (!kho_fdt) + fdt_page = alloc_page(GFP_KERNEL); + if (!fdt_page) return -ENOMEM;
- fdt = page_to_virt(kho_fdt); + fdt = page_to_virt(fdt_page);
err |= fdt_create(fdt, PAGE_SIZE); err |= fdt_finish_reservemap(fdt); @@ -2499,7 +2464,10 @@ static int __init prepare_kho_fdt(void) err |= fdt_property_string(fdt, "compatible", MEMBLOCK_KHO_NODE_COMPATIBLE); for (i = 0; i < reserved_mem_count; i++) { struct reserve_mem_table *map = &reserved_mem_table[i]; + struct page *page = phys_to_page(map->start); + unsigned int nr_pages = map->size >> PAGE_SHIFT;
+ err |= kho_preserve_pages(page, nr_pages); err |= fdt_begin_node(fdt, map->name); err |= fdt_property_string(fdt, "compatible", RESERVE_MEM_KHO_NODE_COMPATIBLE); err |= fdt_property(fdt, "start", &map->start, sizeof(map->start)); @@ -2507,13 +2475,16 @@ static int __init prepare_kho_fdt(void) err |= fdt_end_node(fdt); } err |= fdt_end_node(fdt); - err |= fdt_finish(fdt);
+ err |= kho_preserve_folio(page_folio(fdt_page)); + + if (!err) + err = kho_add_subtree(MEMBLOCK_KHO_FDT, fdt); + if (err) { pr_err("failed to prepare memblock FDT for KHO: %d\n", err); - put_page(kho_fdt); - kho_fdt = NULL; + put_page(fdt_page); }
return err; @@ -2529,13 +2500,6 @@ static int __init reserve_mem_init(void) err = prepare_kho_fdt(); if (err) return err; - - err = register_kho_notifier(&reserve_mem_kho_nb); - if (err) { - put_page(kho_fdt); - kho_fdt = NULL; - } - return err; } late_initcall(reserve_mem_init);
Allow users of KHO to cancel the previous preservation by adding the necessary interfaces to unpreserve folio, pages, and vmallocs.
Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Pratyush Yadav pratyush@kernel.org Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org --- include/linux/kexec_handover.h | 18 ++++++ kernel/kexec_handover.c | 104 ++++++++++++++++++++++++++++----- 2 files changed, 109 insertions(+), 13 deletions(-)
diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index 0d860d793b66..80ece4232617 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -43,8 +43,11 @@ bool kho_is_enabled(void); bool is_kho_boot(void);
int kho_preserve_folio(struct folio *folio); +int kho_unpreserve_folio(struct folio *folio); int kho_preserve_pages(struct page *page, unsigned int nr_pages); +int kho_unpreserve_pages(struct page *page, unsigned int nr_pages); int kho_preserve_vmalloc(void *ptr, struct kho_vmalloc *preservation); +int kho_unpreserve_vmalloc(struct kho_vmalloc *preservation); struct folio *kho_restore_folio(phys_addr_t phys); struct page *kho_restore_pages(phys_addr_t phys, unsigned int nr_pages); void *kho_restore_vmalloc(const struct kho_vmalloc *preservation); @@ -72,17 +75,32 @@ static inline int kho_preserve_folio(struct folio *folio) return -EOPNOTSUPP; }
+static inline int kho_unpreserve_folio(struct folio *folio) +{ + return -EOPNOTSUPP; +} + static inline int kho_preserve_pages(struct page *page, unsigned int nr_pages) { return -EOPNOTSUPP; }
+static inline int kho_unpreserve_pages(struct page *page, unsigned int nr_pages) +{ + return -EOPNOTSUPP; +} + static inline int kho_preserve_vmalloc(void *ptr, struct kho_vmalloc *preservation) { return -EOPNOTSUPP; }
+static inline int kho_unpreserve_vmalloc(struct kho_vmalloc *preservation) +{ + return -EOPNOTSUPP; +} + static inline struct folio *kho_restore_folio(phys_addr_t phys) { return NULL; diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index 82137eba1474..c514b300ebe6 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -157,26 +157,33 @@ static void *xa_load_or_alloc(struct xarray *xa, unsigned long index) return no_free_ptr(elm); }
-static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn, - unsigned long end_pfn) +static void __kho_unpreserve_order(struct kho_mem_track *track, unsigned long pfn, + unsigned int order) { struct kho_mem_phys_bits *bits; struct kho_mem_phys *physxa; + const unsigned long pfn_high = pfn >> order;
- while (pfn < end_pfn) { - const unsigned int order = - min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn)); - const unsigned long pfn_high = pfn >> order; + physxa = xa_load(&track->orders, order); + if (!physxa) + return;
- physxa = xa_load(&track->orders, order); - if (!physxa) - continue; + bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS); + if (!bits) + return;
- bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS); - if (!bits) - continue; + clear_bit(pfn_high % PRESERVE_BITS, bits->preserve); +} + +static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn, + unsigned long end_pfn) +{ + unsigned int order; + + while (pfn < end_pfn) { + order = min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn));
- clear_bit(pfn_high % PRESERVE_BITS, bits->preserve); + __kho_unpreserve_order(track, pfn, order);
pfn += 1 << order; } @@ -745,6 +752,30 @@ int kho_preserve_folio(struct folio *folio) } EXPORT_SYMBOL_GPL(kho_preserve_folio);
+/** + * kho_unpreserve_folio - unpreserve a folio. + * @folio: folio to unpreserve. + * + * Instructs KHO to unpreserve a folio that was preserved by + * kho_preserve_folio() before. The provided @folio (pfn and order) + * must exactly match a previously preserved folio. + * + * Return: 0 on success, error code on failure + */ +int kho_unpreserve_folio(struct folio *folio) +{ + const unsigned long pfn = folio_pfn(folio); + const unsigned int order = folio_order(folio); + struct kho_mem_track *track = &kho_out.track; + + if (kho_out.finalized) + return -EBUSY; + + __kho_unpreserve_order(track, pfn, order); + return 0; +} +EXPORT_SYMBOL_GPL(kho_unpreserve_folio); + /** * kho_preserve_pages - preserve contiguous pages across kexec * @page: first page in the list. @@ -789,6 +820,33 @@ int kho_preserve_pages(struct page *page, unsigned int nr_pages) } EXPORT_SYMBOL_GPL(kho_preserve_pages);
+/** + * kho_unpreserve_pages - unpreserve contiguous pages. + * @page: first page in the list. + * @nr_pages: number of pages. + * + * Instructs KHO to unpreserve @nr_pages contiguous pages starting from @page. + * This must be called with the same @page and @nr_pages as the corresponding + * kho_preserve_pages() call. Unpreserving arbitrary sub-ranges of larger + * preserved blocks is not supported. + * + * Return: 0 on success, error code on failure + */ +int kho_unpreserve_pages(struct page *page, unsigned int nr_pages) +{ + struct kho_mem_track *track = &kho_out.track; + const unsigned long start_pfn = page_to_pfn(page); + const unsigned long end_pfn = start_pfn + nr_pages; + + if (kho_out.finalized) + return -EBUSY; + + __kho_unpreserve(track, start_pfn, end_pfn); + + return 0; +} +EXPORT_SYMBOL_GPL(kho_unpreserve_pages); + struct kho_vmalloc_hdr { DECLARE_KHOSER_PTR(next, struct kho_vmalloc_chunk *); }; @@ -949,6 +1007,26 @@ int kho_preserve_vmalloc(void *ptr, struct kho_vmalloc *preservation) } EXPORT_SYMBOL_GPL(kho_preserve_vmalloc);
+/** + * kho_unpreserve_vmalloc - unpreserve memory allocated with vmalloc() + * @preservation: preservation metadata returned by kho_preserve_vmalloc() + * + * Instructs KHO to unpreserve the area in vmalloc address space that was + * previously preserved with kho_preserve_vmalloc(). + * + * Return: 0 on success, error code on failure + */ +int kho_unpreserve_vmalloc(struct kho_vmalloc *preservation) +{ + if (kho_out.finalized) + return -EBUSY; + + kho_vmalloc_free_chunks(preservation); + + return 0; +} +EXPORT_SYMBOL_GPL(kho_unpreserve_vmalloc); + /** * kho_restore_vmalloc - recreates and populates an area in vmalloc address * space from the preserved memory.
Hi Pasha,
On Sat, Nov 01 2025, Pasha Tatashin wrote:
Allow users of KHO to cancel the previous preservation by adding the necessary interfaces to unpreserve folio, pages, and vmallocs.
Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Pratyush Yadav pratyush@kernel.org Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org
[...]
+/**
- kho_unpreserve_vmalloc - unpreserve memory allocated with vmalloc()
- @preservation: preservation metadata returned by kho_preserve_vmalloc()
- Instructs KHO to unpreserve the area in vmalloc address space that was
- previously preserved with kho_preserve_vmalloc().
- Return: 0 on success, error code on failure
- */
+int kho_unpreserve_vmalloc(struct kho_vmalloc *preservation) +{
- if (kho_out.finalized)
return -EBUSY;- kho_vmalloc_free_chunks(preservation);
When reviewing this patch, I spotted that kho_vmalloc_free_chunks() is broken. Well it happens to work if all pages are 0-order, but breaks on higher-order allocations.
I have sent a separate patch [0] to fix this on top of mm-stable. It doesn't have a conflict with this patch so it shouldn't cause trouble. And I **don't** think it should block this patch either. This is mostly a heads up.
[0] https://lore.kernel.org/linux-mm/20251103180235.71409-2-pratyush@kernel.org/...
If there is an error half way through KHO memory preservation, we should rollback and unpreserve everything that is partially preserved.
Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Suggested-by: Pratyush Yadav pratyush@kernel.org --- mm/memblock.c | 73 ++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 58 insertions(+), 15 deletions(-)
diff --git a/mm/memblock.c b/mm/memblock.c index e3bef9b35d63..f527ad1ca682 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2445,29 +2445,60 @@ int reserve_mem_release_by_name(const char *name) #define MEMBLOCK_KHO_NODE_COMPATIBLE "memblock-v1" #define RESERVE_MEM_KHO_NODE_COMPATIBLE "reserve-mem-v1"
+static int __init reserved_mem_preserve(void) +{ + unsigned int nr_preserved = 0; + int err; + + for (unsigned int i = 0; i < reserved_mem_count; i++, nr_preserved++) { + struct reserve_mem_table *map = &reserved_mem_table[i]; + struct page *page = phys_to_page(map->start); + unsigned int nr_pages = map->size >> PAGE_SHIFT; + + err = kho_preserve_pages(page, nr_pages); + if (err) + goto err_unpreserve; + } + + return 0; + +err_unpreserve: + for (unsigned int i = 0; i < nr_preserved; i++) { + struct reserve_mem_table *map = &reserved_mem_table[i]; + struct page *page = phys_to_page(map->start); + unsigned int nr_pages = map->size >> PAGE_SHIFT; + + kho_unpreserve_pages(page, nr_pages); + } + + return err; +} + static int __init prepare_kho_fdt(void) { - int err = 0, i; struct page *fdt_page; void *fdt; + int err;
fdt_page = alloc_page(GFP_KERNEL); - if (!fdt_page) - return -ENOMEM; + if (!fdt_page) { + err = -ENOMEM; + goto err_no_fdt_page; + }
fdt = page_to_virt(fdt_page); + err = kho_preserve_pages(fdt_page, 1); + if (err) + goto err_free_fdt;
err |= fdt_create(fdt, PAGE_SIZE); err |= fdt_finish_reservemap(fdt); - err |= fdt_begin_node(fdt, ""); err |= fdt_property_string(fdt, "compatible", MEMBLOCK_KHO_NODE_COMPATIBLE); - for (i = 0; i < reserved_mem_count; i++) { + + for (unsigned int i = 0; !err && i < reserved_mem_count; i++) { struct reserve_mem_table *map = &reserved_mem_table[i]; - struct page *page = phys_to_page(map->start); - unsigned int nr_pages = map->size >> PAGE_SHIFT;
- err |= kho_preserve_pages(page, nr_pages); err |= fdt_begin_node(fdt, map->name); err |= fdt_property_string(fdt, "compatible", RESERVE_MEM_KHO_NODE_COMPATIBLE); err |= fdt_property(fdt, "start", &map->start, sizeof(map->start)); @@ -2477,15 +2508,27 @@ static int __init prepare_kho_fdt(void) err |= fdt_end_node(fdt); err |= fdt_finish(fdt);
- err |= kho_preserve_folio(page_folio(fdt_page)); + if (err) + goto err_unpreserve_fdt;
- if (!err) - err = kho_add_subtree(MEMBLOCK_KHO_FDT, fdt); + err = kho_add_subtree(MEMBLOCK_KHO_FDT, fdt); + if (err) + goto err_unpreserve_fdt;
- if (err) { - pr_err("failed to prepare memblock FDT for KHO: %d\n", err); - put_page(fdt_page); - } + err = reserved_mem_preserve(); + if (err) + goto err_remove_subtree; + + return 0; + +err_remove_subtree: + kho_remove_subtree(fdt); +err_unpreserve_fdt: + kho_unpreserve_pages(fdt_page, 1); +err_free_fdt: + put_page(fdt_page); +err_no_fdt_page: + pr_err("failed to prepare memblock FDT for KHO: %d\n", err);
return err; }
On Sat, Nov 01, 2025 at 10:23:20AM -0400, Pasha Tatashin wrote:
If there is an error half way through KHO memory preservation, we should rollback and unpreserve everything that is partially preserved.
Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Suggested-by: Pratyush Yadav pratyush@kernel.org
Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org
with a small nit below.
mm/memblock.c | 73 ++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 58 insertions(+), 15 deletions(-)
diff --git a/mm/memblock.c b/mm/memblock.c index e3bef9b35d63..f527ad1ca682 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2445,29 +2445,60 @@ int reserve_mem_release_by_name(const char *name)
...
static int __init prepare_kho_fdt(void) {
- int err = 0, i; struct page *fdt_page; void *fdt;
- int err;
fdt_page = alloc_page(GFP_KERNEL);
- if (!fdt_page)
return -ENOMEM;
- if (!fdt_page) {
err = -ENOMEM;goto err_no_fdt_page;
Please rename the label to describe what the goto does, say, err_report. I believe it can be a fixup on top after Andrew merges these.
...
+err_remove_subtree:
- kho_remove_subtree(fdt);
+err_unpreserve_fdt:
- kho_unpreserve_pages(fdt_page, 1);
+err_free_fdt:
- put_page(fdt_page);
+err_no_fdt_page:
- pr_err("failed to prepare memblock FDT for KHO: %d\n", err);
return err; } -- 2.51.1.930.gacf6e81ea2-goog
If there is an error half way through KHO memory preservation, we should rollback and unpreserve everything that is partially preserved.
Co-developed-by: Mike Rapoport (Microsoft) rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com --- lib/test_kho.c | 103 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 73 insertions(+), 30 deletions(-)
diff --git a/lib/test_kho.c b/lib/test_kho.c index 9f7cfa6ac855..025ea251a186 100644 --- a/lib/test_kho.c +++ b/lib/test_kho.c @@ -33,17 +33,28 @@ struct kho_test_state { unsigned int nr_folios; struct folio **folios; phys_addr_t *folios_info; + struct kho_vmalloc folios_info_phys; + int nr_folios_preserved; struct folio *fdt; __wsum csum; };
static struct kho_test_state kho_test_state;
-static int kho_test_save_data(struct kho_test_state *state, void *fdt) +static void kho_test_unpreserve_data(struct kho_test_state *state) +{ + for (int i = 0; i < state->nr_folios_preserved; i++) + kho_unpreserve_folio(state->folios[i]); + + kho_unpreserve_vmalloc(&state->folios_info_phys); + vfree(state->folios_info); +} + +static int kho_test_preserve_data(struct kho_test_state *state) { - phys_addr_t *folios_info __free(kvfree) = NULL; struct kho_vmalloc folios_info_phys; - int err = 0; + phys_addr_t *folios_info; + int err;
folios_info = vmalloc_array(state->nr_folios, sizeof(*folios_info)); if (!folios_info) @@ -51,64 +62,98 @@ static int kho_test_save_data(struct kho_test_state *state, void *fdt)
err = kho_preserve_vmalloc(folios_info, &folios_info_phys); if (err) - return err; + goto err_free_info; + + state->folios_info_phys = folios_info_phys; + state->folios_info = folios_info;
for (int i = 0; i < state->nr_folios; i++) { struct folio *folio = state->folios[i]; unsigned int order = folio_order(folio);
folios_info[i] = virt_to_phys(folio_address(folio)) | order; - err = kho_preserve_folio(folio); if (err) - break; + goto err_unpreserve; + state->nr_folios_preserved++; }
+ return 0; + +err_unpreserve: + /* + * kho_test_unpreserve_data frees folio_info, bail out immediately to + * avoid double free + */ + kho_test_unpreserve_data(state); + return err; + +err_free_info: + vfree(folios_info); + return err; +} + +static int kho_test_prepare_fdt(struct kho_test_state *state, ssize_t fdt_size) +{ + const char compatible[] = KHO_TEST_COMPAT; + unsigned int magic = KHO_TEST_MAGIC; + void *fdt = folio_address(state->fdt); + int err; + + err = fdt_create(fdt, fdt_size); + err |= fdt_finish_reservemap(fdt); + err |= fdt_begin_node(fdt, ""); + err |= fdt_property(fdt, "compatible", compatible, sizeof(compatible)); + err |= fdt_property(fdt, "magic", &magic, sizeof(magic)); + err |= fdt_begin_node(fdt, "data"); err |= fdt_property(fdt, "nr_folios", &state->nr_folios, sizeof(state->nr_folios)); - err |= fdt_property(fdt, "folios_info", &folios_info_phys, - sizeof(folios_info_phys)); + err |= fdt_property(fdt, "folios_info", &state->folios_info_phys, + sizeof(state->folios_info_phys)); err |= fdt_property(fdt, "csum", &state->csum, sizeof(state->csum)); err |= fdt_end_node(fdt);
- if (!err) - state->folios_info = no_free_ptr(folios_info); + err |= fdt_end_node(fdt); + err |= fdt_finish(fdt);
return err; }
-static int kho_test_prepare_fdt(struct kho_test_state *state) +static int kho_test_preserve(struct kho_test_state *state) { - const char compatible[] = KHO_TEST_COMPAT; - unsigned int magic = KHO_TEST_MAGIC; ssize_t fdt_size; - int err = 0; - void *fdt; + int err;
fdt_size = state->nr_folios * sizeof(phys_addr_t) + PAGE_SIZE; state->fdt = folio_alloc(GFP_KERNEL, get_order(fdt_size)); if (!state->fdt) return -ENOMEM;
- fdt = folio_address(state->fdt); - - err |= kho_preserve_folio(state->fdt); - err |= fdt_create(fdt, fdt_size); - err |= fdt_finish_reservemap(fdt); + err = kho_preserve_folio(state->fdt); + if (err) + goto err_free_fdt;
- err |= fdt_begin_node(fdt, ""); - err |= fdt_property(fdt, "compatible", compatible, sizeof(compatible)); - err |= fdt_property(fdt, "magic", &magic, sizeof(magic)); - err |= kho_test_save_data(state, fdt); - err |= fdt_end_node(fdt); + err = kho_test_preserve_data(state); + if (err) + goto err_unpreserve_fdt;
- err |= fdt_finish(fdt); + err = kho_test_prepare_fdt(state, fdt_size); + if (err) + goto err_unpreserve_data;
err = kho_add_subtree(KHO_TEST_FDT, folio_address(state->fdt)); if (err) - folio_put(state->fdt); + goto err_unpreserve_data;
+ return 0; + +err_unpreserve_data: + kho_test_unpreserve_data(state); +err_unpreserve_fdt: + kho_unpreserve_folio(state->fdt); +err_free_fdt: + folio_put(state->fdt); return err; }
@@ -174,14 +219,12 @@ static int kho_test_save(void) if (err) goto err_free_folios;
- err = kho_test_prepare_fdt(state); + err = kho_test_preserve(state); if (err) goto err_free_folios;
return 0;
-err_free_fdt: - folio_put(state->fdt); err_free_folios: kvfree(folios); return err;
KHO allows clients to preserve memory regions at any point before the KHO state is finalized. The finalization process itself involves KHO performing its own actions, such as serializing the overall preserved memory map.
If this finalization process is aborted, the current implementation destroys KHO's internal memory tracking structures (`kho_out.ser.track.orders`). This behavior effectively unpreserves all memory from KHO's perspective, regardless of whether those preservations were made by clients before the finalization attempt or by KHO itself during finalization.
This premature unpreservation is incorrect. An abort of the finalization process should only undo actions taken by KHO as part of that specific finalization attempt. Individual memory regions preserved by clients prior to finalization should remain preserved, as their lifecycle is managed by the clients themselves. These clients might still need to call kho_unpreserve_folio() or kho_unpreserve_phys() based on their own logic, even after a KHO finalization attempt is aborted.
Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com --- kernel/kexec_handover.c | 21 +-------------------- 1 file changed, 1 insertion(+), 20 deletions(-)
diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index c514b300ebe6..3adf86c7c2db 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -1118,31 +1118,12 @@ EXPORT_SYMBOL_GPL(kho_restore_vmalloc);
static int __kho_abort(void) { - int err = 0; - unsigned long order; - struct kho_mem_phys *physxa; - - xa_for_each(&kho_out.track.orders, order, physxa) { - struct kho_mem_phys_bits *bits; - unsigned long phys; - - xa_for_each(&physxa->phys_bits, phys, bits) - kfree(bits); - - xa_destroy(&physxa->phys_bits); - kfree(physxa); - } - xa_destroy(&kho_out.track.orders); - if (kho_out.preserved_mem_map) { kho_mem_ser_free(kho_out.preserved_mem_map); kho_out.preserved_mem_map = NULL; }
- if (err) - pr_err("Failed to abort KHO finalization: %d\n", err); - - return err; + return 0; }
int kho_abort(void)
Move KHO to kernel/liveupdate/ in preparation of placing all Live Update core kernel related files to the same place.
Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org --- Documentation/core-api/kho/concepts.rst | 2 +- MAINTAINERS | 2 +- init/Kconfig | 2 + kernel/Kconfig.kexec | 34 ---------------- kernel/Makefile | 4 +- kernel/liveupdate/Kconfig | 39 +++++++++++++++++++ kernel/liveupdate/Makefile | 5 +++ kernel/{ => liveupdate}/kexec_handover.c | 4 +- .../{ => liveupdate}/kexec_handover_debug.c | 0 .../{ => liveupdate}/kexec_handover_debugfs.c | 0 .../kexec_handover_internal.h | 0 11 files changed, 51 insertions(+), 41 deletions(-) create mode 100644 kernel/liveupdate/Kconfig create mode 100644 kernel/liveupdate/Makefile rename kernel/{ => liveupdate}/kexec_handover.c (99%) rename kernel/{ => liveupdate}/kexec_handover_debug.c (100%) rename kernel/{ => liveupdate}/kexec_handover_debugfs.c (100%) rename kernel/{ => liveupdate}/kexec_handover_internal.h (100%)
diff --git a/Documentation/core-api/kho/concepts.rst b/Documentation/core-api/kho/concepts.rst index 36d5c05cfb30..d626d1dbd678 100644 --- a/Documentation/core-api/kho/concepts.rst +++ b/Documentation/core-api/kho/concepts.rst @@ -70,5 +70,5 @@ in the FDT. That state is called the KHO finalization phase.
Public API ========== -.. kernel-doc:: kernel/kexec_handover.c +.. kernel-doc:: kernel/liveupdate/kexec_handover.c :export: diff --git a/MAINTAINERS b/MAINTAINERS index bdd0a1260421..764df916fae7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13795,7 +13795,7 @@ S: Maintained F: Documentation/admin-guide/mm/kho.rst F: Documentation/core-api/kho/* F: include/linux/kexec_handover.h -F: kernel/kexec_handover* +F: kernel/liveupdate/kexec_handover* F: tools/testing/selftests/kho/
KEYS-ENCRYPTED diff --git a/init/Kconfig b/init/Kconfig index cab3ad28ca49..0605de5d96c0 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -2138,6 +2138,8 @@ config TRACEPOINTS
source "kernel/Kconfig.kexec"
+source "kernel/liveupdate/Kconfig" + endmenu # General setup
source "arch/Kconfig" diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec index cc6743137946..15632358bcf7 100644 --- a/kernel/Kconfig.kexec +++ b/kernel/Kconfig.kexec @@ -94,40 +94,6 @@ config KEXEC_JUMP Jump between original kernel and kexeced kernel and invoke code in physical address mode via KEXEC
-config KEXEC_HANDOVER - bool "kexec handover" - depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE - depends on !DEFERRED_STRUCT_PAGE_INIT - select MEMBLOCK_KHO_SCRATCH - select KEXEC_FILE - select LIBFDT - select CMA - help - Allow kexec to hand over state across kernels by generating and - passing additional metadata to the target kernel. This is useful - to keep data or state alive across the kexec. For this to work, - both source and target kernels need to have this option enabled. - -config KEXEC_HANDOVER_DEBUG - bool "Enable Kexec Handover debug checks" - depends on KEXEC_HANDOVER - help - This option enables extra sanity checks for the Kexec Handover - subsystem. Since, KHO performance is crucial in live update - scenarios and the extra code might be adding overhead it is - only optionally enabled. - -config KEXEC_HANDOVER_DEBUGFS - bool "kexec handover debugfs interface" - default KEXEC_HANDOVER - depends on KEXEC_HANDOVER - select DEBUG_FS - help - Allow to control kexec handover device tree via debugfs - interface, i.e. finalize the state or aborting the finalization. - Also, enables inspecting the KHO fdt trees with the debugfs binary - blobs. - config CRASH_DUMP bool "kernel crash dumps" default ARCH_DEFAULT_CRASH_DUMP diff --git a/kernel/Makefile b/kernel/Makefile index 2cf7909a74e5..e83669841b8c 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -52,6 +52,7 @@ obj-y += printk/ obj-y += irq/ obj-y += rcu/ obj-y += livepatch/ +obj-y += liveupdate/ obj-y += dma/ obj-y += entry/ obj-y += unwind/ @@ -82,9 +83,6 @@ obj-$(CONFIG_CRASH_DUMP_KUNIT_TEST) += crash_core_test.o obj-$(CONFIG_KEXEC) += kexec.o obj-$(CONFIG_KEXEC_FILE) += kexec_file.o obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o -obj-$(CONFIG_KEXEC_HANDOVER) += kexec_handover.o -obj-$(CONFIG_KEXEC_HANDOVER_DEBUG) += kexec_handover_debug.o -obj-$(CONFIG_KEXEC_HANDOVER_DEBUGFS) += kexec_handover_debugfs.o obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o obj-$(CONFIG_COMPAT) += compat.o obj-$(CONFIG_CGROUPS) += cgroup/ diff --git a/kernel/liveupdate/Kconfig b/kernel/liveupdate/Kconfig new file mode 100644 index 000000000000..1379a4c40b09 --- /dev/null +++ b/kernel/liveupdate/Kconfig @@ -0,0 +1,39 @@ +# SPDX-License-Identifier: GPL-2.0-only + +menu "Live Update and Kexec HandOver" + +config KEXEC_HANDOVER + bool "kexec handover" + depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE + depends on !DEFERRED_STRUCT_PAGE_INIT + select MEMBLOCK_KHO_SCRATCH + select KEXEC_FILE + select LIBFDT + select CMA + help + Allow kexec to hand over state across kernels by generating and + passing additional metadata to the target kernel. This is useful + to keep data or state alive across the kexec. For this to work, + both source and target kernels need to have this option enabled. + +config KEXEC_HANDOVER_DEBUG + bool "Enable Kexec Handover debug checks" + depends on KEXEC_HANDOVER + help + This option enables extra sanity checks for the Kexec Handover + subsystem. Since, KHO performance is crucial in live update + scenarios and the extra code might be adding overhead it is + only optionally enabled. + +config KEXEC_HANDOVER_DEBUGFS + bool "kexec handover debugfs interface" + default KEXEC_HANDOVER + depends on KEXEC_HANDOVER + select DEBUG_FS + help + Allow to control kexec handover device tree via debugfs + interface, i.e. finalize the state or aborting the finalization. + Also, enables inspecting the KHO fdt trees with the debugfs binary + blobs. + +endmenu diff --git a/kernel/liveupdate/Makefile b/kernel/liveupdate/Makefile new file mode 100644 index 000000000000..f52ce1ebcf86 --- /dev/null +++ b/kernel/liveupdate/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-$(CONFIG_KEXEC_HANDOVER) += kexec_handover.o +obj-$(CONFIG_KEXEC_HANDOVER_DEBUG) += kexec_handover_debug.o +obj-$(CONFIG_KEXEC_HANDOVER_DEBUGFS) += kexec_handover_debugfs.o diff --git a/kernel/kexec_handover.c b/kernel/liveupdate/kexec_handover.c similarity index 99% rename from kernel/kexec_handover.c rename to kernel/liveupdate/kexec_handover.c index 3adf86c7c2db..be945c133a2f 100644 --- a/kernel/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -26,8 +26,8 @@ * KHO is tightly coupled with mm init and needs access to some of mm * internal APIs. */ -#include "../mm/internal.h" -#include "kexec_internal.h" +#include "../../mm/internal.h" +#include "../kexec_internal.h" #include "kexec_handover_internal.h"
#define KHO_FDT_COMPATIBLE "kho-v1" diff --git a/kernel/kexec_handover_debug.c b/kernel/liveupdate/kexec_handover_debug.c similarity index 100% rename from kernel/kexec_handover_debug.c rename to kernel/liveupdate/kexec_handover_debug.c diff --git a/kernel/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c similarity index 100% rename from kernel/kexec_handover_debugfs.c rename to kernel/liveupdate/kexec_handover_debugfs.c diff --git a/kernel/kexec_handover_internal.h b/kernel/liveupdate/kexec_handover_internal.h similarity index 100% rename from kernel/kexec_handover_internal.h rename to kernel/liveupdate/kexec_handover_internal.h
Changyuan does not have cycles to commit to the upstream work of KHO. Remove from KHO maintainers.
Signed-off-by: Changyuan Lyu changyuanl@google.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com --- MAINTAINERS | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/MAINTAINERS b/MAINTAINERS index 764df916fae7..6200de2027fe 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13788,7 +13788,7 @@ F: kernel/kexec* KEXEC HANDOVER (KHO) M: Alexander Graf graf@amazon.com M: Mike Rapoport rppt@kernel.org -M: Changyuan Lyu changyuanl@google.com +M: Pasha Tatashin pasha.tatashin@soleen.com L: kexec@lists.infradead.org L: linux-mm@kvack.org S: Maintained
On Sat, Nov 01, 2025 at 10:23:24AM -0400, Pasha Tatashin wrote:
Changyuan does not have cycles to commit to the upstream work of KHO. Remove from KHO maintainers.
Signed-off-by: Changyuan Lyu changyuanl@google.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com
Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org
MAINTAINERS | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/MAINTAINERS b/MAINTAINERS index 764df916fae7..6200de2027fe 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13788,7 +13788,7 @@ F: kernel/kexec* KEXEC HANDOVER (KHO) M: Alexander Graf graf@amazon.com M: Mike Rapoport rppt@kernel.org -M: Changyuan Lyu changyuanl@google.com +M: Pasha Tatashin pasha.tatashin@soleen.com L: kexec@lists.infradead.org L: linux-mm@kvack.org S: Maintained -- 2.51.1.930.gacf6e81ea2-goog
From: Zhu Yanjun yanjun.zhu@linux.dev
Make pr_xxx() call to use the %pe format specifier instead of %d. The %pe specifier prints a symbolic error string (e.g., -ENOMEM, -EINVAL) when given an error pointer created with ERR_PTR(err).
This change enhances the clarity and diagnostic value of the error message by showing a descriptive error name rather than a numeric error code.
Note, that some err are still printed by value, as those errors might come from libfdt and not regular errnos.
Signed-off-by: Zhu Yanjun yanjun.zhu@linux.dev Co-developed-by: Pasha Tatashin pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Simon Horman horms@kernel.org --- kernel/liveupdate/kexec_handover.c | 4 ++-- kernel/liveupdate/kexec_handover_debugfs.c | 10 ++++++---- 2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index be945c133a2f..167c761988d3 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -1448,8 +1448,8 @@ void __init kho_populate(phys_addr_t fdt_phys, u64 fdt_len, memblock_add(area->addr, size); err = memblock_mark_kho_scratch(area->addr, size); if (WARN_ON(err)) { - pr_warn("failed to mark the scratch region 0x%pa+0x%pa: %d", - &area->addr, &size, err); + pr_warn("failed to mark the scratch region 0x%pa+0x%pa: %pe", + &area->addr, &size, ERR_PTR(err)); goto out; } pr_debug("Marked 0x%pa+0x%pa as scratch", &area->addr, &size); diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c index 46e9e6c0791f..ac739d25094d 100644 --- a/kernel/liveupdate/kexec_handover_debugfs.c +++ b/kernel/liveupdate/kexec_handover_debugfs.c @@ -150,8 +150,8 @@ __init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt) err = __kho_debugfs_fdt_add(&dbg->fdt_list, sub_fdt_dir, name, phys_to_virt(*fdt_phys)); if (err) { - pr_warn("failed to add fdt %s to debugfs: %d\n", name, - err); + pr_warn("failed to add fdt %s to debugfs: %pe\n", name, + ERR_PTR(err)); continue; } } @@ -168,8 +168,10 @@ __init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt) * reviving state from KHO and setting up KHO for the next * kexec. */ - if (err) - pr_err("failed exposing handover FDT in debugfs: %d\n", err); + if (err) { + pr_err("failed exposing handover FDT in debugfs: %pe\n", + ERR_PTR(err)); + } }
__init int kho_out_debugfs_init(struct kho_debugfs *dbg)
在 2025/11/1 7:23, Pasha Tatashin 写道:
From: Zhu Yanjun yanjun.zhu@linux.dev
Make pr_xxx() call to use the %pe format specifier instead of %d. The %pe specifier prints a symbolic error string (e.g., -ENOMEM, -EINVAL) when given an error pointer created with ERR_PTR(err).
This change enhances the clarity and diagnostic value of the error message by showing a descriptive error name rather than a numeric error code.
Note, that some err are still printed by value, as those errors might come from libfdt and not regular errnos.
Signed-off-by: Zhu Yanjun yanjun.zhu@linux.dev Co-developed-by: Pasha Tatashin pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com
Appreciate your help, Pasha
Yanjun.Zhu
Reviewed-by: Simon Horman horms@kernel.org
kernel/liveupdate/kexec_handover.c | 4 ++-- kernel/liveupdate/kexec_handover_debugfs.c | 10 ++++++---- 2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index be945c133a2f..167c761988d3 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -1448,8 +1448,8 @@ void __init kho_populate(phys_addr_t fdt_phys, u64 fdt_len, memblock_add(area->addr, size); err = memblock_mark_kho_scratch(area->addr, size); if (WARN_ON(err)) {
pr_warn("failed to mark the scratch region 0x%pa+0x%pa: %d",&area->addr, &size, err);
pr_warn("failed to mark the scratch region 0x%pa+0x%pa: %pe",&area->addr, &size, ERR_PTR(err)); goto out;diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c index 46e9e6c0791f..ac739d25094d 100644 --- a/kernel/liveupdate/kexec_handover_debugfs.c +++ b/kernel/liveupdate/kexec_handover_debugfs.c @@ -150,8 +150,8 @@ __init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt) err = __kho_debugfs_fdt_add(&dbg->fdt_list, sub_fdt_dir, name, phys_to_virt(*fdt_phys)); if (err) {
pr_warn("failed to add fdt %s to debugfs: %d\n", name,err);
pr_warn("failed to add fdt %s to debugfs: %pe\n", name,ERR_PTR(err)); continue;@@ -168,8 +168,10 @@ __init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt) * reviving state from KHO and setting up KHO for the next * kexec. */
- if (err)
pr_err("failed exposing handover FDT in debugfs: %d\n", err);
- if (err) {
pr_err("failed exposing handover FDT in debugfs: %pe\n",ERR_PTR(err));- } }
__init int kho_out_debugfs_init(struct kho_debugfs *dbg)
On Sat, Nov 01, 2025 at 10:23:25AM -0400, Pasha Tatashin wrote:
From: Zhu Yanjun yanjun.zhu@linux.dev
Make pr_xxx() call to use the %pe format specifier instead of %d. The %pe specifier prints a symbolic error string (e.g., -ENOMEM, -EINVAL) when given an error pointer created with ERR_PTR(err).
This change enhances the clarity and diagnostic value of the error message by showing a descriptive error name rather than a numeric error code.
Note, that some err are still printed by value, as those errors might come from libfdt and not regular errnos.
Signed-off-by: Zhu Yanjun yanjun.zhu@linux.dev Co-developed-by: Pasha Tatashin pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Simon Horman horms@kernel.org
Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org
kernel/liveupdate/kexec_handover.c | 4 ++-- kernel/liveupdate/kexec_handover_debugfs.c | 10 ++++++---- 2 files changed, 8 insertions(+), 6 deletions(-)
On Sat, Nov 01 2025, Pasha Tatashin wrote:
From: Zhu Yanjun yanjun.zhu@linux.dev
Make pr_xxx() call to use the %pe format specifier instead of %d. The %pe specifier prints a symbolic error string (e.g., -ENOMEM, -EINVAL) when given an error pointer created with ERR_PTR(err).
This change enhances the clarity and diagnostic value of the error message by showing a descriptive error name rather than a numeric error code.
Note, that some err are still printed by value, as those errors might come from libfdt and not regular errnos.
There is fdt_strerror() that does this for libfdt errnos. Something to do in a follow up patch I suppose.
Signed-off-by: Zhu Yanjun yanjun.zhu@linux.dev Co-developed-by: Pasha Tatashin pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Simon Horman horms@kernel.org
Reviewed-by: Pratyush Yadav pratyush@kernel.org
[...]
linux-kselftest-mirror@lists.linaro.org
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Mike Rapoport -
Pasha Tatashin -
Pratyush Yadav -
Zhu Yanjun