From nobody Tue Feb 10 10:18:44 2026 Received: from mail-yw1-f171.google.com (mail-yw1-f171.google.com [209.85.128.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 836A42E1C7A for ; Fri, 14 Nov 2025 19:00:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763146823; cv=none; b=hTpDgO58q8bcxGODpR8ReXNjeJO+4Du2ijEH+OOzgCMZ08n4BOfzF+MK0ipO/dtMo/5S2PDiJnVJm0QLC/HP1XRGElrPPvfWpsCl+iIXUSzaxJNPa0uxykV+Drf0aOv4IttAwXTDxlpDb79hJqQCojD8DTxmb2lgFPtu7CCW18I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763146823; c=relaxed/simple; bh=ObPb7rYcD0sksQl5nozqQKKzSdYIbEg6yhfuX2l2xOs=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SxBPgzcobj+VwFl4iUS8RXQ7NQRAOtevTlODQVJIZ7AHm8EdT5TKcmC7VEhSE1Y9NOhZ7lvS8zLqpU8sBuIHI5JjJ/dkh/jHJ2xwmqWbir7/ZH98cFMBPiQnElXh8w4/KqEarmpKFwdTIusc/9xHLL4UnkEseP8ULvR+dvjs6Ko= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=soleen.com; spf=pass smtp.mailfrom=soleen.com; dkim=pass (2048-bit key) header.d=soleen.com header.i=@soleen.com header.b=UBdV/b9f; arc=none smtp.client-ip=209.85.128.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=soleen.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=soleen.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=soleen.com header.i=@soleen.com header.b="UBdV/b9f" Received: by mail-yw1-f171.google.com with SMTP id 00721157ae682-7815092cd0bso23026887b3.2 for ; Fri, 14 Nov 2025 11:00:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; t=1763146818; x=1763751618; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=7N5yt00Qno1MwWJjfGBPy1ItOdOrLJaGZ6crOfgTrsk=; b=UBdV/b9faXURjHGZAkHEd483Rp6wYfBxLoiE4WGXZLInlTfkBnWjXDmiOiqBaJ+waD 95pFR/hhIymMfrdOEFck0HeBeexAo8ebH7Jy7kF3K2kOMlS4uDCy/GrMRigKWUhm4b5z v6G0S14lzCcj2HwDP5LWf7lyePKNu4qLR0JCNaJvWzyFc8WBb0f+wRtgtGPN1b6CQdKu puZsNS8tZX44PyZscM3Kw0mXSfkX9kh1iVJ3GCeEcSj9SpU8CGvWagTrCD4tYdDtz5yA KlqZIW2w7MZEI7YX1Qec0gJBiADwa5bJHx9dBO3qtibVDcUFB2CoyCyvLJ4KVHjZh8rr JNrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763146818; x=1763751618; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=7N5yt00Qno1MwWJjfGBPy1ItOdOrLJaGZ6crOfgTrsk=; b=DORlP3VdCcyibEUqVXB6rRjZqaF5A1IJSqFXUUcXHM9/r0OkTist8eMGlLIRtDOu1K YzCjwfHlPupyxZJ1WrkG2DGgh7zXez+mCdQ386j7nTf2Xw1t9b3EgZ4LJooRlczTvg05 igzYpdWjI51w5p+hTm8LUdOgE4YwWDIWiTRqh1uNFuXK/buyhSZhOnIsp6SRf+WrIAKr QRY8ZikyEnBVFhumfk36KpxObM36L/1wFAseQexBX3jZfEsHEFvXsfbzF4vpJSdep4iJ gFog8gOgGCwq+JI347BqkaZt4cWl+YlS47C0TrlB/4RkndAEX9TMYsXLQtAwzHI5cGG1 I+Wg== X-Forwarded-Encrypted: i=1; AJvYcCWNa2+V+LzfVWffgT8qbcucIXXmOk/exgjv+NFBA91ieOgypwH/ZubP4xX8UwcxDfb8rcO1gmCf36EHc8o=@vger.kernel.org X-Gm-Message-State: AOJu0YyDEA7c0WfQNVQM3oDP0SG+dC9QlfzGst+4w2TIP53efta5ThIC 0S0TfEJjCatKBaVZ4xJtPSE5FJoLz54pyitqUSFyaH5dpasQybiKAAE0WIqELlp82Tk= X-Gm-Gg: ASbGncvYCwu31ADY6EG9JvKgiqo317FRmDMFcM3/iX6fFyFWh1V88hSeciUJl655s3c f5rBKAuHkbCNzMt30C07DJRuipvGRZ40XwfrZl3bc41i52BXphtJt73wsCffE9GYUUgNR/+uZhd Lh9neQOZgJtziFE9DNh3tXngZ4/pBcUE30Ctuj5ifsMwWgk3HZpy0pwdKMnifO/hUTBfN1znaLK gSPbeUtJaVcwXkxzsdkP01QZMC/gAlKpc5HbLMw3YsGM2EnLntg+MqdKqsctUb5UDHYpWSM9sJp Zum4bAGFe8h4GKls5Ty0dBxOzo+owcJtharPODgz2Y9GkkDyC4AmuS2esczf/OLFSQWSzsLZh3h mixzH2nARxzfhtGosO6ScM4hoD1rp/peUeorYdI8yfVIm/lYFHkm5O3lioS8T6LPv29infEOQse MnZpFTxwM2ISyzmNogjFsxuyBWgO9UmG55/xnyW3wSr1oCZRsAU5bGcY0HvTKhDpsILUJ6 X-Google-Smtp-Source: AGHT+IEgGDASb7ywJuNlU8tH7U5fvJZheQWqPab57YBnjKIGG/4PXsbTcQgkrxJdQmu9tDmb9/dD3A== X-Received: by 2002:a05:690c:338b:b0:783:6f8d:e7a6 with SMTP id 00721157ae682-78929ef6a1bmr60582517b3.51.1763146817769; Fri, 14 Nov 2025 11:00:17 -0800 (PST) Received: from soleen.c.googlers.com.com (182.221.85.34.bc.googleusercontent.com. [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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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_h= andover.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 { =20 struct khoser_mem_chunk; =20 -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 */ =20 - 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 =3D { .track =3D { .orders =3D XARRAY_INIT(kho_out.track.orders, 0), }, - .sub_fdts =3D LIST_HEAD_INIT(kho_out.sub_fdts), - .fdts_lock =3D __MUTEX_INITIALIZER(kho_out.fdts_lock), .finalized =3D false, }; =20 @@ -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 =3D virt_to_phys(fdt); + void *root_fdt =3D kho_out.fdt; + int err =3D -ENOMEM; + int off, fdt_err; =20 - sub_fdt =3D kmalloc(sizeof(*sub_fdt), GFP_KERNEL); - if (!sub_fdt) - return -ENOMEM; + guard(mutex)(&kho_out.lock); + + fdt_err =3D fdt_open_into(root_fdt, root_fdt, PAGE_SIZE); + if (fdt_err < 0) + return err; =20 - INIT_LIST_HEAD(&sub_fdt->l); - sub_fdt->name =3D name; - sub_fdt->fdt =3D fdt; + off =3D fdt_add_subnode(root_fdt, 0, name); + if (off < 0) { + if (off =3D=3D -FDT_ERR_EXISTS) + err =3D -EEXIST; + goto out_pack; + } + + err =3D fdt_setprop(root_fdt, off, PROP_SUB_FDT, &phys, sizeof(phys)); + if (err < 0) + goto out_pack; =20 - 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)); =20 - return 0; +out_pack: + fdt_pack(root_fdt); + + return err; } EXPORT_SYMBOL_GPL(kho_add_subtree); =20 void kho_remove_subtree(void *fdt) { - struct kho_sub_fdt *sub_fdt; + phys_addr_t target_phys =3D virt_to_phys(fdt); + void *root_fdt =3D kho_out.fdt; + int off; + int err; + + guard(mutex)(&kho_out.lock); + + err =3D fdt_open_into(root_fdt, root_fdt, PAGE_SIZE); + if (err < 0) + return; + + for (off =3D fdt_first_subnode(root_fdt, 0); off >=3D 0; + off =3D fdt_next_subnode(root_fdt, off)) { + const u64 *val; + int len; + + val =3D fdt_getprop(root_fdt, off, PROP_SUB_FDT, &len); + if (!val || len !=3D sizeof(phys_addr_t)) + continue; =20 - guard(mutex)(&kho_out.fdts_lock); - list_for_each_entry(sub_fdt, &kho_out.sub_fdts, l) { - if (sub_fdt->fdt =3D=3D fdt) { - list_del(&sub_fdt->l); - kfree(sub_fdt); + if ((phys_addr_t)*val =3D=3D 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); =20 @@ -1232,48 +1251,6 @@ void kho_restore_free(void *mem) } EXPORT_SYMBOL_GPL(kho_restore_free); =20 -static int __kho_finalize(void) -{ - void *root =3D kho_out.fdt; - struct kho_sub_fdt *fdt; - u64 empty_mem_map =3D 0; - int err; - - err =3D fdt_create(root, PAGE_SIZE); - err |=3D fdt_finish_reservemap(root); - err |=3D fdt_begin_node(root, ""); - err |=3D fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE); - err |=3D 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 =3D virt_to_phys(fdt->fdt); - - err |=3D fdt_begin_node(root, fdt->name); - err |=3D fdt_property(root, PROP_SUB_FDT, &phys, sizeof(phys)); - err |=3D fdt_end_node(root); - } - mutex_unlock(&kho_out.fdts_lock); - - err |=3D fdt_end_node(root); - err |=3D fdt_finish(root); - if (err) - goto err_exit; - - err =3D 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; =20 guard(mutex)(&kho_out.lock); - if (kho_out.finalized) { - kho_update_memory_map(NULL); - kho_out.finalized =3D false; - } - - ret =3D __kho_finalize(); + ret =3D kho_mem_serialize(&kho_out); if (ret) return ret; =20 @@ -1372,6 +1344,24 @@ int kho_retrieve_subtree(const char *name, phys_addr= _t *phys) } EXPORT_SYMBOL_GPL(kho_retrieve_subtree); =20 +static __init int kho_out_fdt_setup(void) +{ + void *root =3D kho_out.fdt; + u64 empty_mem_map =3D 0; + int err; + + err =3D fdt_create(root, PAGE_SIZE); + err |=3D fdt_finish_reservemap(root); + err |=3D fdt_begin_node(root, ""); + err |=3D fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE); + err |=3D fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map, + sizeof(empty_mem_map)); + err |=3D fdt_end_node(root); + err |=3D fdt_finish(root); + + return err; +} + static __init int kho_init(void) { const void *fdt =3D kho_get_fdt(); @@ -1394,6 +1384,10 @@ static __init int kho_init(void) if (err) goto err_free_fdt; =20 + err =3D kho_out_fdt_setup(); + if (err) + goto err_free_fdt; + if (fdt) { kho_in_debugfs_init(&kho_in.dbg, fdt); return 0; --=20 2.52.0.rc1.455.g30608eb744-goog