From 70f9133096c833922c3b63461480248cefa7bb0f Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (Microsoft)" Date: Sat, 1 Nov 2025 10:23:18 -0400 Subject: kho: drop notifiers 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. Link: https://lkml.kernel.org/r/20251101142325.1326536-3-pasha.tatashin@soleen.com Signed-off-by: Mike Rapoport (Microsoft) Co-developed-by: Pasha Tatashin Signed-off-by: Pasha Tatashin Cc: Alexander Graf Cc: Changyuan Lyu Cc: Christian Brauner Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: Jonathan Corbet Cc: Masahiro Yamada Cc: Miguel Ojeda Cc: Pratyush Yadav Cc: Randy Dunlap Cc: Simon Horman Cc: Tejun Heo Cc: Zhu Yanjun Signed-off-by: Andrew Morton --- lib/test_kho.c | 35 +++-------------------------------- 1 file changed, 3 insertions(+), 32 deletions(-) (limited to 'lib/test_kho.c') diff --git a/lib/test_kho.c b/lib/test_kho.c index fff018e5548d..27618c5b4796 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: @@ -329,7 +300,7 @@ 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); -- cgit From ce405ed5102018946f20b69c1e7ae49697dcf616 Mon Sep 17 00:00:00 2001 From: Pasha Tatashin Date: Sat, 1 Nov 2025 10:23:21 -0400 Subject: test_kho: unpreserve memory in case of error If there is an error half way through KHO memory preservation, we should rollback and unpreserve everything that is partially preserved. Link: https://lkml.kernel.org/r/20251101142325.1326536-6-pasha.tatashin@soleen.com Co-developed-by: Mike Rapoport (Microsoft) Signed-off-by: Mike Rapoport (Microsoft) Signed-off-by: Pasha Tatashin Cc: Alexander Graf Cc: Changyuan Lyu Cc: Christian Brauner Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: Jonathan Corbet Cc: Masahiro Yamada Cc: Miguel Ojeda Cc: Pratyush Yadav Cc: Randy Dunlap Cc: Simon Horman Cc: Tejun Heo Cc: Zhu Yanjun Signed-off-by: Andrew Morton --- lib/test_kho.c | 103 ++++++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 73 insertions(+), 30 deletions(-) (limited to 'lib/test_kho.c') diff --git a/lib/test_kho.c b/lib/test_kho.c index 27618c5b4796..85b60d87a50a 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; -- cgit From 11047466eff28cb3d3422622166931204ed7d502 Mon Sep 17 00:00:00 2001 From: Pratyush Yadav Date: Tue, 18 Nov 2025 19:10:45 +0100 Subject: test_kho: always print restore status Currently the KHO test only prints a message on success, and remains silent on failure. This makes it difficult to notice a failing test. A failing test is usually more interesting than a successful one. Always print the test status after attempting restore. Link: https://lkml.kernel.org/r/20251118181046.23321-1-pratyush@kernel.org Signed-off-by: Pratyush Yadav Reviewed-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) Acked-by: SeongJae Park Cc: Alexander Graf Cc: Pratyush Yadav Signed-off-by: Andrew Morton --- lib/test_kho.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'lib/test_kho.c') diff --git a/lib/test_kho.c b/lib/test_kho.c index 85b60d87a50a..47de56280795 100644 --- a/lib/test_kho.c +++ b/lib/test_kho.c @@ -306,7 +306,6 @@ static int kho_test_restore(phys_addr_t fdt_phys) if (err) return err; - pr_info("KHO restore succeeded\n"); return 0; } @@ -319,8 +318,15 @@ static int __init kho_test_init(void) return 0; err = kho_retrieve_subtree(KHO_TEST_FDT, &fdt_phys); - if (!err) - return kho_test_restore(fdt_phys); + if (!err) { + err = kho_test_restore(fdt_phys); + if (err) + pr_err("KHO restore failed\n"); + else + pr_info("KHO restore succeeded\n"); + + return err; + } if (err != -ENOENT) { pr_warn("failed to retrieve %s FDT: %d\n", KHO_TEST_FDT, err); -- cgit