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[34.85.221.182]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-6410e8f4f2esm2014058d50.0.2025.11.14.11.00.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 11:00:17 -0800 (PST) From: Pasha Tatashin To: akpm@linux-foundation.org, bhe@redhat.com, pasha.tatashin@soleen.com, rppt@kernel.org, jasonmiu@google.com, arnd@arndb.de, coxu@redhat.com, dave@vasilevsky.ca, ebiggers@google.com, graf@amazon.com, kees@kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: [PATCH v2 10/13] kho: Update FDT dynamically for subtree addition/removal Date: Fri, 14 Nov 2025 13:59:59 -0500 Message-ID: <20251114190002.3311679-11-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog In-Reply-To: <20251114190002.3311679-1-pasha.tatashin@soleen.com> References: <20251114190002.3311679-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 3feuwd51b7sdgsjhe6z1ggmrp1sdrzxd X-Rspam-User: X-Rspamd-Queue-Id: DF813C0014 X-Rspamd-Server: rspam10 X-HE-Tag: 1763146818-206582 X-HE-Meta: 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 C7QEpZfL Ima1wR38AI2yaQllGkZQ8kTTyngWgPJNEDrZQJdaBxRWGjg2sRGWAZ8IrsFBdNAGjr7ea5vO/GRSyRqpS8d/wjSLRdrZ/d/mj26TNdbj8cxWQ2A2aEKSkYTiEcrOlVxG2tsTGOtThSNzzU7BBNFWAsuOjYvyKwqHAYz86JUFwPV2mqArTKLJPRHdM707QCUQc3fiQdkZupEX9WBL1DsTsZM5RLmdmd0ndqCD8hZxo36Uq/Z2btA+LIeolFKWthEOLRC4OoqT69E6UZD+Q6H4ld2R9p91QSxyK2E8zEkcvoXayKdPg2U2eTgwVcaHU6rWONMAftLyehqkTHZWCFsAsAjUyuL+3HIqspXe6 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently, sub-FDTs were tracked in a list (kho_out.sub_fdts) and the final FDT is constructed entirely from scratch during kho_finalize(). We can maintain the FDT dynamically: 1. Initialize a valid, empty FDT in kho_init(). 2. Use fdt_add_subnode and fdt_setprop in kho_add_subtree to update the FDT immediately when a subsystem registers. 3. Use fdt_del_node in kho_remove_subtree to remove entries. This removes the need for the intermediate sub_fdts list and the reconstruction logic in kho_finalize(). kho_finalize() now only needs to trigger memory map serialization. Signed-off-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Pratyush Yadav --- kernel/liveupdate/kexec_handover.c | 144 ++++++++++++++--------------- 1 file changed, 69 insertions(+), 75 deletions(-) diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index 624fd648d21f..461d96084c12 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -104,20 +104,11 @@ struct kho_mem_track { struct khoser_mem_chunk; -struct kho_sub_fdt { - struct list_head l; - const char *name; - void *fdt; -}; - struct kho_out { 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; struct kho_debugfs dbg; }; @@ -127,8 +118,6 @@ static struct kho_out kho_out = { .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, }; @@ -725,37 +714,67 @@ static void __init kho_reserve_scratch(void) */ int kho_add_subtree(const char *name, void *fdt) { - struct kho_sub_fdt *sub_fdt; + phys_addr_t phys = virt_to_phys(fdt); + void *root_fdt = kho_out.fdt; + int err = -ENOMEM; + int off, fdt_err; - sub_fdt = kmalloc(sizeof(*sub_fdt), GFP_KERNEL); - if (!sub_fdt) - return -ENOMEM; + guard(mutex)(&kho_out.lock); + + fdt_err = fdt_open_into(root_fdt, root_fdt, PAGE_SIZE); + if (fdt_err < 0) + return err; - INIT_LIST_HEAD(&sub_fdt->l); - sub_fdt->name = name; - sub_fdt->fdt = fdt; + off = fdt_add_subnode(root_fdt, 0, name); + if (off < 0) { + if (off == -FDT_ERR_EXISTS) + err = -EEXIST; + goto out_pack; + } + + err = fdt_setprop(root_fdt, off, PROP_SUB_FDT, &phys, sizeof(phys)); + if (err < 0) + goto out_pack; - 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)); - return 0; +out_pack: + fdt_pack(root_fdt); + + return err; } EXPORT_SYMBOL_GPL(kho_add_subtree); void kho_remove_subtree(void *fdt) { - struct kho_sub_fdt *sub_fdt; + phys_addr_t target_phys = virt_to_phys(fdt); + void *root_fdt = kho_out.fdt; + int off; + int err; + + guard(mutex)(&kho_out.lock); + + err = fdt_open_into(root_fdt, root_fdt, PAGE_SIZE); + if (err < 0) + return; + + for (off = fdt_first_subnode(root_fdt, 0); off >= 0; + off = fdt_next_subnode(root_fdt, off)) { + const u64 *val; + int len; + + val = fdt_getprop(root_fdt, off, PROP_SUB_FDT, &len); + if (!val || len != sizeof(phys_addr_t)) + continue; - 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); + if ((phys_addr_t)*val == target_phys) { + fdt_del_node(root_fdt, off); kho_debugfs_fdt_remove(&kho_out.dbg, fdt); break; } } + + fdt_pack(root_fdt); } EXPORT_SYMBOL_GPL(kho_remove_subtree); @@ -1232,48 +1251,6 @@ void kho_restore_free(void *mem) } EXPORT_SYMBOL_GPL(kho_restore_free); -static int __kho_finalize(void) -{ - void *root = kho_out.fdt; - struct kho_sub_fdt *fdt; - u64 empty_mem_map = 0; - int err; - - 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); - err |= fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map, - sizeof(empty_mem_map)); - if (err) - goto err_exit; - - 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); - - 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(root); - err |= fdt_finish(root); - if (err) - goto err_exit; - - err = kho_mem_serialize(&kho_out); - if (err) - goto err_exit; - - return 0; - -err_exit: - pr_err("Failed to convert KHO state tree: %d\n", err); - return err; -} - int kho_finalize(void) { int ret; @@ -1282,12 +1259,7 @@ int kho_finalize(void) return -EOPNOTSUPP; guard(mutex)(&kho_out.lock); - if (kho_out.finalized) { - kho_update_memory_map(NULL); - kho_out.finalized = false; - } - - ret = __kho_finalize(); + ret = kho_mem_serialize(&kho_out); if (ret) return ret; @@ -1372,6 +1344,24 @@ int kho_retrieve_subtree(const char *name, phys_addr_t *phys) } EXPORT_SYMBOL_GPL(kho_retrieve_subtree); +static __init int kho_out_fdt_setup(void) +{ + void *root = kho_out.fdt; + u64 empty_mem_map = 0; + int err; + + 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); + err |= fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map, + sizeof(empty_mem_map)); + err |= fdt_end_node(root); + err |= fdt_finish(root); + + return err; +} + static __init int kho_init(void) { const void *fdt = kho_get_fdt(); @@ -1394,6 +1384,10 @@ static __init int kho_init(void) if (err) goto err_free_fdt; + err = kho_out_fdt_setup(); + if (err) + goto err_free_fdt; + if (fdt) { kho_in_debugfs_init(&kho_in.dbg, fdt); return 0; -- 2.52.0.rc1.455.g30608eb744-goog