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AL+hErH+pyoj0iUwBXCa/d9Pp/153ywAyFCZ4z2bU/kZPpawcOWoQl1Yy4MDCAboK6FiqSENqwdSef5cgMwrqUX7du7Y@lists.infradead.org X-Gm-Message-State: APuU4Z8J1+fJTJ82Roq4kM2FNSPFlC8TKf9xP7v6+cdotUK4mEl2UX9k WHYDhW+dYLR0RVuE4az8IdWZb2edBF6vCsD3eYaQkD07coYRRxq8WLpZeRLDPVGbnEsacqOfzfn RRU4yHyDXsz3nIWV0JqXfkg== X-Received: from wmo18.prod.google.com ([2002:a05:600c:2312:b0:4a5:34a9:6903]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600d:82f1:b0:4a2:cbe:beac with SMTP id 5b1f17b1804b1-4ba093c85ebmr40371365e9.23.1794395303273; Wed, 11 Nov 2026 03:08:23 -0800 (PST) Date: Wed, 11 Nov 2026 11:07:31 +0000 In-Reply-To: <20261111110738.872947-1-vdonnefort@google.com> X-Archived-By: Mime-Version: 1.0 References: <20261111110738.872947-1-vdonnefort@google.com> X-Mailer: git-send-email 2.56.0.542.g3ef89b7020-goog Message-ID: <20261111110738.872947-2-vdonnefort@google.com> Subject: [PATCH v3 1/8] memblock: Introduce MEMBLOCK_PTEMAP From: Vincent Donnefort To: catalin.marinas@arm.com, will@kernel.org, rppt@kernel.org, akpm@linux-foundation.org, m.szyprowski@samsung.com, jenswi@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org Cc: mark.rutland@arm.com, robin.murphy@arm.com, hch@lst.de, ryan.roberts@arm.com, sumit.garg@kernel.org, sudeep.holla@kernel.org, ardb@kernel.org, thierry.reding@kernel.org, david@kernel.org, danielmentz@google.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, iommu@lists.linux.dev, op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261111_030826_725331_3C183682 X-CRM114-Status: GOOD ( 18.00 ) X-Spam-Score: -9.5 (---------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-26.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Keeping PTE-level mappings is interesting for arm64 as it allows mapping/unmapping pages from the kernel direct map without the risk of splitting blocks which, under the break-before-make rule, may trigger page-faults the kernel can't handle. However, mapping the entire direct map at PTE-level is costly. So instead, create a new memblock flag MEMBLOCK_PTEMAP to selectively apply a PTE-level mapping. Signed-off-by: Vincent Donnefort --- include/linux/memblock.h | 9 +++++++++ mm/memblock.c | 39 +++++++++++++++++++++++++++++++++++++-- 2 files changed, 46 insertions(+), 2 deletions(-) diff --git a/include/linux/memblock.h b/include/linux/memblock.h index 40e6e0aa2f8d..67ef20a1c5e2 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -52,6 +52,7 @@ extern unsigned long long max_possible_pfn; * know is good to use. It is the only memory that allocations may happen from * in this phase. * @MEMBLOCK_RSRV_HUGETLB: memory is reserved for hugetlb pages + * @MEMBLOCK_PTEMAP: memory region to be mapped using PTE-level mapping */ enum memblock_flags { MEMBLOCK_NONE = 0x0, /* No special request */ @@ -63,6 +64,7 @@ enum memblock_flags { MEMBLOCK_RSRV_KERN = 0x20, /* memory reserved for kernel use */ MEMBLOCK_KHO_NOPRSRV = 0x40, /* memory with no KHO preservations */ MEMBLOCK_RSRV_HUGETLB = 0x80, /* memory reserved for hugetlb pages */ + MEMBLOCK_PTEMAP = 0x100,/* PTE-level mapping */ }; /** @@ -160,6 +162,8 @@ int memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t size); int memblock_reserved_mark_kern(phys_addr_t base, phys_addr_t size); int memblock_mark_kho_noprsrv(phys_addr_t base, phys_addr_t size); int memblock_clear_kho_noprsrv(phys_addr_t base, phys_addr_t size); +int memblock_mark_ptemap(phys_addr_t base, phys_addr_t size); +int memblock_clear_ptemap(phys_addr_t base, phys_addr_t size); void memblock_free(void *ptr, size_t size); @@ -305,6 +309,11 @@ static inline bool memblock_is_kho_noprsrv(struct memblock_region *m) return m->flags & MEMBLOCK_KHO_NOPRSRV; } +static inline bool memblock_is_ptemap(struct memblock_region *m) +{ + return m->flags & MEMBLOCK_PTEMAP; +} + int memblock_search_pfn_nid(unsigned long pfn, unsigned long *start_pfn, unsigned long *end_pfn); void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn, diff --git a/mm/memblock.c b/mm/memblock.c index a450092a80fb..b8b6e762917a 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1068,10 +1068,15 @@ static int __init_memblock memblock_setclr_flag(struct memblock_type *type, for (i = start_rgn; i < end_rgn; i++) { struct memblock_region *r = &type->regions[i]; - if (set) + if (set) { + enum memblock_flags map_flags = + MEMBLOCK_NOMAP | MEMBLOCK_PTEMAP; + r->flags |= flag; - else + WARN_ON_ONCE((r->flags & map_flags) == map_flags); + } else { r->flags &= ~flag; + } } memblock_merge_regions(type, start_rgn, end_rgn); @@ -1221,6 +1226,35 @@ __init int memblock_clear_kho_noprsrv(phys_addr_t base, phys_addr_t size) MEMBLOCK_KHO_NOPRSRV); } +/** + * memblock_mark_ptemap - Mark a memory region with flag MEMBLOCK_PTEMAP. + * @base: the base phys addr of the region + * @size: the size of the region + * + * If supported by the architecture, such region is mapped using PTE-level + * mappings in the kernel direct map. + * + * Return: 0 on success, -errno on failure. + */ +int __init_memblock memblock_mark_ptemap(phys_addr_t base, phys_addr_t size) +{ + return memblock_setclr_flag(&memblock.memory, base, size, 1, + MEMBLOCK_PTEMAP); +} + +/** + * memblock_clear_ptemap - Clear flag MEMBLOCK_PTEMAP for a specified region. + * @base: the base phys addr of the region + * @size: the size of the region + * + * Return: 0 on success, -errno on failure. + */ +int __init_memblock memblock_clear_ptemap(phys_addr_t base, phys_addr_t size) +{ + return memblock_setclr_flag(&memblock.memory, base, size, 0, + MEMBLOCK_PTEMAP); +} + static bool should_skip_region(struct memblock_type *type, struct memblock_region *m, int nid, int flags) @@ -2854,6 +2888,7 @@ static const char * const flagname[] = { [ilog2(MEMBLOCK_RSRV_KERN)] = "RSV_KERN", [ilog2(MEMBLOCK_KHO_NOPRSRV)] = "KHO_NOPRSRV", [ilog2(MEMBLOCK_RSRV_HUGETLB)] = "RSV_HUGETLB", + [ilog2(MEMBLOCK_PTEMAP)] = "PTEMAP", }; static int memblock_debug_show(struct seq_file *m, void *private) -- 2.56.0.542.g3ef89b7020-goog