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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-Rspamd-Queue-Id: 5138B40006 X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: n9tpij4hrid5k3ruujrk13fdgs7n5mg8 X-HE-Tag: 1755678266-369836 X-HE-Meta: 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 Ip80tzl9 urfv2cE1bmWGIUiGyGB2sIdlvYONQEYgJ5zdi 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: 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.