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[34.85.221.182]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78822125317sm16468577b3.37.2025.11.14.07.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 07:54:09 -0800 (PST) From: Pasha Tatashin To: akpm@linux-foundation.org, bhe@redhat.com, pasha.tatashin@soleen.com, rppt@kernel.org, jasonmiu@google.com, arnd@arndb.de, coxu@redhat.com, dave@vasilevsky.ca, ebiggers@google.com, graf@amazon.com, kees@kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: [PATCH v1 07/13] kho: Remove global preserved_mem_map and store state in FDT Date: Fri, 14 Nov 2025 10:53:52 -0500 Message-ID: <20251114155358.2884014-8-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog In-Reply-To: <20251114155358.2884014-1-pasha.tatashin@soleen.com> References: <20251114155358.2884014-1-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently, the serialized memory map is tracked via kho_out.preserved_mem_map and copied to the FDT during finalization. This double tracking is redundant. Remove preserved_mem_map from kho_out. Instead, maintain the physical address of the head chunk directly in the preserved-memory-map FDT property. Introduce kho_update_memory_map() to manage this property. This function handles: 1. Retrieving and freeing any existing serialized map (handling the abort/retry case). 2. Updating the FDT property with the new chunk address. This establishes the FDT as the single source of truth for the handover state. Signed-off-by: Pasha Tatashin Reviewed-by: Pratyush Yadav --- kernel/liveupdate/kexec_handover.c | 43 ++++++++++++++++++------------ 1 file changed, 26 insertions(+), 17 deletions(-) diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_h= andover.c index aea58e5a6b49..f1c3dd1ef680 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -117,9 +117,6 @@ struct kho_out { struct mutex fdts_lock; =20 struct kho_mem_track track; - /* First chunk of serialized preserved memory map */ - struct khoser_mem_chunk *preserved_mem_map; - struct kho_debugfs dbg; }; =20 @@ -380,6 +377,27 @@ static void kho_mem_ser_free(struct khoser_mem_chunk *= first_chunk) } } =20 +/* + * Update memory map property, if old one is found discard it via + * kho_mem_ser_free(). + */ +static void kho_update_memory_map(struct khoser_mem_chunk *first_chunk) +{ + void *ptr; + u64 phys; + + ptr =3D fdt_getprop_w(kho_out.fdt, 0, PROP_PRESERVED_MEMORY_MAP, NULL); + + /* Check and discard previous memory map */ + memcpy(&phys, ptr, sizeof(u64)); + if (phys) + kho_mem_ser_free((struct khoser_mem_chunk *)phys_to_virt(phys)); + + /* Update with the new value */ + phys =3D first_chunk ? (u64)virt_to_phys(first_chunk) : 0; + memcpy(ptr, &phys, sizeof(u64)); +} + static int kho_mem_serialize(struct kho_out *kho_out) { struct khoser_mem_chunk *first_chunk =3D NULL; @@ -420,7 +438,7 @@ static int kho_mem_serialize(struct kho_out *kho_out) } } =20 - kho_out->preserved_mem_map =3D first_chunk; + kho_update_memory_map(first_chunk); =20 return 0; =20 @@ -1136,8 +1154,7 @@ int kho_abort(void) if (!kho_out.finalized) return -ENOENT; =20 - kho_mem_ser_free(kho_out.preserved_mem_map); - kho_out.preserved_mem_map =3D NULL; + kho_update_memory_map(NULL); kho_out.finalized =3D false; =20 return 0; @@ -1147,21 +1164,15 @@ static int __kho_finalize(void) { void *root =3D kho_out.fdt; struct kho_sub_fdt *fdt; - u64 *preserved_mem_map; + u64 empty_mem_map =3D 0; int err; =20 err =3D fdt_create(root, PAGE_SIZE); err |=3D fdt_finish_reservemap(root); err |=3D fdt_begin_node(root, ""); err |=3D fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE); - /** - * Reserve the preserved-memory-map property in the root FDT, so - * that all property definitions will precede subnodes created by - * KHO callers. - */ - err |=3D fdt_property_placeholder(root, PROP_PRESERVED_MEMORY_MAP, - sizeof(*preserved_mem_map), - (void **)&preserved_mem_map); + err |=3D fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map, + sizeof(empty_mem_map)); if (err) goto err_exit; =20 @@ -1184,8 +1195,6 @@ static int __kho_finalize(void) if (err) goto err_exit; =20 - *preserved_mem_map =3D (u64)virt_to_phys(kho_out.preserved_mem_map); - return 0; =20 err_exit: --=20 2.52.0.rc1.455.g30608eb744-goog