From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E8B32D8DC0; Wed, 20 Aug 2025 08:24:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755678265; cv=none; b=BTchOfRxi+raqRIFYbnoBFkATM/PnsjYibc1oHSf93NUDN5d8kwW9n1Ak4Sp4iHnen1zsO87X5hjE0tBonGXBLwmUcj6l6kx617BX/jQyhhMW+MTvk/PFLzOyQ+dnRJ4gz5cl31+JgQptp0rjAHnjowioek6wfk3gtvCdZRb7Q8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755678265; c=relaxed/simple; bh=/UL8r/IY6NvhVlFJ56nhpLYKbxUYOgISlF8+SOKUMgE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Klk1hMav25xfd/ZKTB9PXWreqq+tTSql0l+JZ7HFI5ZvETctPNxk89ORpVHt44mR8MUa8IjBdbIqJ2HNEV7H3FYb3JAS5Cxz79mHShYIjdHJ+5oq5VNqF0MoTkX+qhBS0SQmihlsopV/MGc9786YsC6A7fqIIkXOn8CKMkHQKSA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sbnMh56e; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sbnMh56e" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7043f4da31390c58bb7721a3774c30998997df44.1755643201.git.epetron@amazon.de> 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.