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Fri, 01 May 2026 02:49:29 -0700 (PDT) From: Cris Jacob Maamor To: Mike Rapoport , Pasha Tatashin , Pratyush Yadav Cc: Alexander Graf , Andrew Morton , Dan Carpenter , Greg Kroah-Hartman , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC 1/5] kexec: handover: add helper to check preserved page ranges Date: Fri, 1 May 2026 17:46:33 +0800 Message-ID: <20260501094637.38650-2-crisjacobmaamor@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260501094637.38650-1-crisjacobmaamor@gmail.com> References: <20260501094637.38650-1-crisjacobmaamor@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: fpg41nnkskdgi9xcb315mphirt5btbgk X-Rspamd-Queue-Id: 6DA9140007 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1777628971-123624 X-HE-Meta: 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 /nEK6NrH 5zhYV/Qovj4GDu2azTUC44y8mJbp1sQy83xy57bMMflM6FUwAr5rOz1HESwY4ASfWu+T2SliZFP317HO5nBizWTlLPzvnfPaA+vWjir2/M0ceuJcIPJrlCKEllXNsMEK2HMejU+Qcawh/77jhcuW7dtPMQsm0CcWOxBMfP/4k53Wxcf+u7HfAOaBKFvXok9T9quobP+yLTGQpXffXXf1tRDG6a3jf8k9XaQwaSWornj05gPSCZTXfIxaST+sbT1hi3qL7geTctbSiMbOcuj7ty4CiLL4eWlVmS8PuzhsstY3HN0BRgb4nhSzBSDHmqG0Wd/tinoXEjMh2w+gt7ZNkkyEw7sWoGBp7OwBXmfTBwGQBs0xKlNFLr0Vr4Q914MSnunB89dH6BHCpje3HsML6j/dwBel6JvDlsc7OBpDwEYx42CFLPNhyoqqWM+MUVU7YbRBOYG3mORcyz5c= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Signed-off-by: Cris Jacob Maamor --- include/linux/kexec_handover.h | 6 +++++ kernel/liveupdate/kexec_handover.c | 35 ++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index 8968c56d2d73..fb09943ab232 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -19,6 +19,7 @@ struct page; #ifdef CONFIG_KEXEC_HANDOVER bool kho_is_enabled(void); bool is_kho_boot(void); +bool kho_is_preserved(phys_addr_t phys, unsigned long nr_pages); int kho_preserve_folio(struct folio *folio); void kho_unpreserve_folio(struct folio *folio); @@ -51,6 +52,11 @@ static inline bool is_kho_boot(void) return false; } +static inline bool kho_is_preserved(phys_addr_t phys, unsigned long nr_pages) +{ + return false; +} + static inline int kho_preserve_folio(struct folio *folio) { return -EOPNOTSUPP; diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index 94762de1fe5f..fe9f11190705 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -10,6 +10,7 @@ #define pr_fmt(fmt) "KHO: " fmt +#include #include #include #include @@ -429,6 +430,40 @@ static struct page *kho_restore_page(phys_addr_t phys, bool is_folio) return page; } +/** + * kho_is_preserved - Verify that a physical page range belongs to KHO. + * @phys: physical address of the first page in the range. + * @nr_pages: number of pages that the caller expects to access. + * + * Use this before phys_to_virt() when a physical address comes from restored + * metadata. It checks that @phys starts a KHO-preserved allocation large + * enough to cover @nr_pages. + * + * This only checks the KHO marker. It does not restore, free, or take + * ownership of the pages. + * + * Return: true if @phys starts a preserved KHO allocation large enough to cover + * @nr_pages, false otherwise. + */ +bool kho_is_preserved(phys_addr_t phys, unsigned long nr_pages) +{ + struct page *page; + union kho_page_info info; + + if (!nr_pages || !IS_ALIGNED(phys, PAGE_SIZE)) + return false; + + page = pfn_to_online_page(PHYS_PFN(phys)); + if (!page) + return false; + + info.page_private = page->private; + if (info.magic != KHO_PAGE_MAGIC || info.order >= BITS_PER_LONG) + return false; + + return nr_pages <= BIT(info.order); +} + /** * kho_restore_folio - recreates the folio from the preserved memory. * @phys: physical address of the folio. -- 2.53.0