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[34.85.247.235]) by smtp.gmail.com with ESMTPSA id 00721157ae682-719532c7e4fsm30482117b3.72.2025.07.23.07.47.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Jul 2025 07:47:07 -0700 (PDT) From: Pasha Tatashin To: pratyush@kernel.org, jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, pasha.tatashin@soleen.com, rppt@kernel.org, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, zhangguopeng@kylinos.cn, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, gregkh@linuxfoundation.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, ptyadav@amazon.de, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, jgg@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com Subject: [PATCH v2 07/32] kho: add interfaces to unpreserve folios and physical memory ranges Date: Wed, 23 Jul 2025 14:46:20 +0000 Message-ID: <20250723144649.1696299-8-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog In-Reply-To: <20250723144649.1696299-1-pasha.tatashin@soleen.com> References: <20250723144649.1696299-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 3dn7a5apnn4i3qp5o68pip8bua5i6rgk X-Rspam-User: X-Rspamd-Queue-Id: 8A56440012 X-Rspamd-Server: rspam02 X-HE-Tag: 1753282029-901670 X-HE-Meta: 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 2F8whQsE 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 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: From: Changyuan Lyu Allow users of KHO to cancel the previous preservation by adding the necessary interfaces to unpreserve folio. Signed-off-by: Changyuan Lyu Co-developed-by: Pasha Tatashin Signed-off-by: Pasha Tatashin --- include/linux/kexec_handover.h | 12 +++++ kernel/kexec_handover.c | 90 +++++++++++++++++++++++++++++----- 2 files changed, 89 insertions(+), 13 deletions(-) diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index cabdff5f50a2..383e9460edb9 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -33,7 +33,9 @@ struct folio; bool kho_is_enabled(void); int kho_preserve_folio(struct folio *folio); +int kho_unpreserve_folio(struct folio *folio); int kho_preserve_phys(phys_addr_t phys, size_t size); +int kho_unpreserve_phys(phys_addr_t phys, size_t size); struct folio *kho_restore_folio(phys_addr_t phys); int kho_add_subtree(const char *name, void *fdt); void kho_remove_subtree(void *fdt); @@ -58,11 +60,21 @@ static inline int kho_preserve_folio(struct folio *folio) return -EOPNOTSUPP; } +static inline int kho_unpreserve_folio(struct folio *folio) +{ + return -EOPNOTSUPP; +} + static inline int kho_preserve_phys(phys_addr_t phys, size_t size) { return -EOPNOTSUPP; } +static inline int kho_unpreserve_phys(phys_addr_t phys, size_t size) +{ + return -EOPNOTSUPP; +} + static inline struct folio *kho_restore_folio(phys_addr_t phys) { return NULL; diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index 30d673f7f68a..26ad926912a7 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -136,26 +136,33 @@ static void *xa_load_or_alloc(struct xarray *xa, unsigned long index, size_t sz) return elm; } -static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn, - unsigned long end_pfn) +static void __kho_unpreserve_order(struct kho_mem_track *track, unsigned long pfn, + unsigned int order) { struct kho_mem_phys_bits *bits; struct kho_mem_phys *physxa; + const unsigned long pfn_high = pfn >> order; - while (pfn < end_pfn) { - const unsigned int order = - min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn)); - const unsigned long pfn_high = pfn >> order; + physxa = xa_load(&track->orders, order); + if (!physxa) + return; - physxa = xa_load(&track->orders, order); - if (!physxa) - continue; + bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS); + if (!bits) + return; - bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS); - if (!bits) - continue; + clear_bit(pfn_high % PRESERVE_BITS, bits->preserve); +} - clear_bit(pfn_high % PRESERVE_BITS, bits->preserve); +static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn, + unsigned long end_pfn) +{ + unsigned int order; + + while (pfn < end_pfn) { + order = min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn)); + + __kho_unpreserve_order(track, pfn, order); pfn += 1 << order; } @@ -667,6 +674,30 @@ int kho_preserve_folio(struct folio *folio) } EXPORT_SYMBOL_GPL(kho_preserve_folio); +/** + * kho_unpreserve_folio - unpreserve a folio. + * @folio: folio to unpreserve. + * + * Instructs KHO to unpreserve a folio that was preserved by + * kho_preserve_folio() before. The provided @folio (pfn and order) + * must exactly match a previously preserved folio. + * + * Return: 0 on success, error code on failure + */ +int kho_unpreserve_folio(struct folio *folio) +{ + const unsigned long pfn = folio_pfn(folio); + const unsigned int order = folio_order(folio); + struct kho_mem_track *track = &kho_out.track; + + if (kho_out.finalized) + return -EBUSY; + + __kho_unpreserve_order(track, pfn, order); + return 0; +} +EXPORT_SYMBOL_GPL(kho_unpreserve_folio); + /** * kho_preserve_phys - preserve a physically contiguous range across kexec. * @phys: physical address of the range. @@ -712,6 +743,39 @@ int kho_preserve_phys(phys_addr_t phys, size_t size) } EXPORT_SYMBOL_GPL(kho_preserve_phys); +/** + * kho_unpreserve_phys - unpreserve a physically contiguous range. + * @phys: physical address of the range. + * @size: size of the range. + * + * Instructs KHO to unpreserve the memory range from @phys to @phys + @size. + * The @phys address must be aligned to @size, and @size must be a + * power-of-2 multiple of PAGE_SIZE. + * This call must exactly match a granularity at which memory was originally + * preserved (either by a `kho_preserve_phys` call with the same `phys` and + * `size`). Unpreserving arbitrary sub-ranges of larger preserved blocks is not + * supported. + * + * Return: 0 on success, error code on failure + */ +int kho_unpreserve_phys(phys_addr_t phys, size_t size) +{ + struct kho_mem_track *track = &kho_out.track; + unsigned long pfn = PHYS_PFN(phys); + unsigned long end_pfn = PHYS_PFN(phys + size); + + if (kho_out.finalized) + return -EBUSY; + + if (!PAGE_ALIGNED(phys) || !PAGE_ALIGNED(size)) + return -EINVAL; + + __kho_unpreserve(track, pfn, end_pfn); + + return 0; +} +EXPORT_SYMBOL_GPL(kho_unpreserve_phys); + static int __kho_abort(void) { int err = 0; -- 2.50.0.727.gbf7dc18ff4-goog