kho: remove finalize state and clients

Eliminate the `kho_finalize()` function and its associated state from the
KHO subsystem.  The transition to a radix tree for memory tracking makes
the explicit "finalize" state and its serialization step obsolete.

Remove the `kho_finalize()` and `kho_finalized()` APIs and their stub
implementations.  Update KHO client code and the debugfs interface to no
longer call or depend on the `kho_finalize()` mechanism.

Complete the move towards a stateless KHO, simplifying the overall design
by removing unnecessary state management.

Link: https://lkml.kernel.org/r/20260206021428.3386442-3-jasonmiu@google.com
Signed-off-by: Jason Miu <jasonmiu@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: David Matlack <dmatlack@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

4 files changed, 2 insertions, 57 deletions

diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index ad877926f3f6..410098bae0bf 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -68,8 +68,7 @@ early_param("kho", kho_parse_enable);
 
 struct kho_out {
 	void *fdt;
-	bool finalized;
-	struct mutex lock; /* protects KHO FDT finalization */
+	struct mutex lock; /* protects KHO FDT */
 
 	struct kho_radix_tree radix_tree;
 	struct kho_debugfs dbg;
@@ -80,7 +79,6 @@ static struct kho_out kho_out = {
 	.radix_tree = {
 		.lock = __MUTEX_INITIALIZER(kho_out.radix_tree.lock),
 	},
-	.finalized = false,
 };
 
 /**
@@ -1241,23 +1239,6 @@ void kho_restore_free(void *mem)
 }
 EXPORT_SYMBOL_GPL(kho_restore_free);
 
-int kho_finalize(void)
-{
-	if (!kho_enable)
-		return -EOPNOTSUPP;
-
-	guard(mutex)(&kho_out.lock);
-	kho_out.finalized = true;
-
-	return 0;
-}
-
-bool kho_finalized(void)
-{
-	guard(mutex)(&kho_out.lock);
-	return kho_out.finalized;
-}
-
 struct kho_in {
 	phys_addr_t fdt_phys;
 	phys_addr_t scratch_phys;
diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c
index 548033fd8a62..acf368222682 100644
--- a/kernel/liveupdate/kexec_handover_debugfs.c
+++ b/kernel/liveupdate/kexec_handover_debugfs.c
@@ -76,24 +76,6 @@ void kho_debugfs_fdt_remove(struct kho_debugfs *dbg, void *fdt)
 	}
 }
 
-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 -EINVAL;
-}
-
-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++)
@@ -199,11 +181,6 @@ __init int kho_out_debugfs_init(struct kho_debugfs *dbg)
 	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;
diff --git a/kernel/liveupdate/kexec_handover_internal.h b/kernel/liveupdate/kexec_handover_internal.h
index 0202c85ad14f..9a832a35254c 100644
--- a/kernel/liveupdate/kexec_handover_internal.h
+++ b/kernel/liveupdate/kexec_handover_internal.h
@@ -22,9 +22,6 @@ struct kho_debugfs {};
 extern struct kho_scratch *kho_scratch;
 extern unsigned int kho_scratch_cnt;
 
-bool kho_finalized(void);
-int kho_finalize(void);
-
 #ifdef CONFIG_KEXEC_HANDOVER_DEBUGFS
 int kho_debugfs_init(void);
 void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt);
diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c
index dda7bb57d421..84ac728d63ba 100644
--- a/kernel/liveupdate/luo_core.c
+++ b/kernel/liveupdate/luo_core.c
@@ -230,17 +230,7 @@ int liveupdate_reboot(void)
 
 	luo_flb_serialize();
 
-	err = kho_finalize();
-	if (err) {
-		pr_err("kho_finalize failed %d\n", err);
-		/*
-		 * kho_finalize() may return libfdt errors, to aboid passing to
-		 * userspace unknown errors, change this to EAGAIN.
-		 */
-		err = -EAGAIN;
-	}
-
-	return err;
+	return 0;
 }
 
 /**