From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 41704CA0EF8 for ; Wed, 20 Aug 2025 09:15:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=dx/UlKEArBGyUs882+KWiBNpdfeER6qBdFtmV4pAR/A=; b=JaChe2TUH9IseZEoDDmRUJcCf9 JL5vsF6ODMcaZwZlIZnzjD4SFPNuWuAanTWV1jLFuG6EjxCHCoHRMs8xHyn4Ba/5ri6s7iwueVJ+l ZbcfiQh6z+rx47ek4G/5ouQPwpkGnQfk6F87bPR6WxiA8RBA5i+QLA27w0lYD9X8Rwq3vlZ55DibG 4hwpXuSjPPZXBalU2EtlRF0BFKLKB2qTuYe8oKClHcSkGZYKXFPv1ZkN+nfkwKFxzEWA6b4QiTYnt 0f+8cmdJgAYixReVLm08N2lURzyE6NTTKv+65ubEmcw9G3sWv6gPVPiqgFVSyJ1Y+BEMbyHCnCR5x qUUt5nSg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uoev1-0000000CsQM-2MZ6; Wed, 20 Aug 2025 09:15:43 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uoe7N-0000000Cj9H-1ldx for kexec@lists.infradead.org; Wed, 20 Aug 2025 08:24:26 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id D885D460DE; Wed, 20 Aug 2025 08:24:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1F1EC4CEEB; Wed, 20 Aug 2025 08:24:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755678264; bh=/UL8r/IY6NvhVlFJ56nhpLYKbxUYOgISlF8+SOKUMgE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sbnMh56e8KeY51vJlnHAVZISzBdTJN0LpMnDGP01/N6PsJeiRuOBNdJEqqYBftNed 20t8gDewYmYyxKTsvLyzMfsjnofAq089lYNh6nQ3CR2ft1qPJ8g50tWqP1VlSpFaN8 hv208x2hK9MsoaUUDNxpuFCOtTSxBEZpRDl9IVRq6pqYaurwMixBNn2Dap3BCak86G vpEYt8K90dH4mn3ZqO2q+XO3FMm5rrL3hNEPk5m6utPgeCIDPZJAVSSSHH/h38EM+M FHsjOO+A9NXCwMNea9+PBpOZpICrX0MeAfBs9XeemKoTu+mXQefKikv7CjZW5vKpIZ xiWbnB6p6lCCQ== Date: Wed, 20 Aug 2025 11:24:17 +0300 From: Mike Rapoport To: Evangelos Petrongonas Cc: Ard Biesheuvel , Alexander Graf , Changyuan Lyu , Andrew Morton , Baoquan He , kexec@lists.infradead.org, linux-mm@kvack.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, nh-open-source@amazon.com Subject: Re: [PATCH v2 1/2] kexec: introduce is_kho_boot() Message-ID: References: <7043f4da31390c58bb7721a3774c30998997df44.1755643201.git.epetron@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7043f4da31390c58bb7721a3774c30998997df44.1755643201.git.epetron@amazon.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250820_012425_498726_30BF021D X-CRM114-Status: GOOD ( 23.45 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Tue, Aug 19, 2025 at 11:22:45PM +0000, Evangelos Petrongonas wrote: > During early initialisation, after a kexec, other components, like EFI > need to know if a KHO enabled kexec is performed. The `kho_is_enabled` > function is not enough as in the early stages, it only reflects > whether the cmdline has KHO enabled, not if an actual KHO FDT exists. > > Extend the KHO API with `is_kho_boot()` to provide a way for components > to check if a KHO enabled kexec is performed. > > Signed-off-by: Evangelos Petrongonas > --- > include/linux/kexec_handover.h | 6 ++++++ > kernel/kexec_handover.c | 20 ++++++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h > index 348844cffb13..559d13a3bc44 100644 > --- a/include/linux/kexec_handover.h > +++ b/include/linux/kexec_handover.h > @@ -40,6 +40,7 @@ struct kho_serialization; > > #ifdef CONFIG_KEXEC_HANDOVER > bool kho_is_enabled(void); > +bool is_kho_boot(void); > > int kho_preserve_folio(struct folio *folio); > int kho_preserve_phys(phys_addr_t phys, size_t size); > @@ -60,6 +61,11 @@ static inline bool kho_is_enabled(void) > return false; > } > > +static inline bool is_kho_boot(void) > +{ > + return false; > +} > + > static inline int kho_preserve_folio(struct folio *folio) > { > return -EOPNOTSUPP; > diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c > index 69b953551677..a1a4e76e0ff1 100644 > --- a/kernel/kexec_handover.c > +++ b/kernel/kexec_handover.c > @@ -925,6 +925,26 @@ static const void *kho_get_fdt(void) > return kho_in.fdt_phys ? phys_to_virt(kho_in.fdt_phys) : NULL; > } > > +/** > + * is_kho_boot - check if current kernel was booted via KHO-enabled > + * kexec > + * > + * This function checks if the current kernel was loaded through a kexec > + * operation with KHO enabled, by verifying both that KHO is enabled via > + * cmdline AND that a valid KHO FDT was passed. > + * > + * Note: This function returns reliable results only after > + * kho_populate() has been called during early boot. Before that, > + * it may return false even if KHO data is present. > + * > + * Return: true if booted via KHO-enabled kexec, false otherwise > + */ > +bool is_kho_boot(void) > +{ > + return !!kho_get_fdt() && kho_enable; Let's drop '&& kho_enable' and presume that a kernel that booted with KHO FDT goes through KHO revival. With that change feel free to add Reviewed-by: Mike Rapoport (Microsoft) > +} > +EXPORT_SYMBOL_GPL(is_kho_boot); > + > /** > * kho_retrieve_subtree - retrieve a preserved sub FDT by its name. > * @name: the name of the sub FDT passed to kho_add_subtree(). > -- > 2.47.3 -- Sincerely yours, Mike.