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s=arc-20220608; d=hostedemail.com; t=1742906215; a=rsa-sha256; cv=none; b=r7Bhjb9HAQv7YYObamVtirP9a4/P1rs4HgdezsUSlYQQpiALaveIUR0+PLWOtYaFl7e2sr 2LYPkyEkE/UhRc5FBeLGTPfGClgaKX25M+Z9xeTexJuRAGunPKZIoQK5fDQ56lhGhcS+Rn N46vn9BHhMO5gfJS7GLmPnGwY/uawJk= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=none; spf=pass (imf20.hostedemail.com: domain of alex@ghiti.fr designates 217.70.183.200 as permitted sender) smtp.mailfrom=alex@ghiti.fr; dmarc=none Received: by mail.gandi.net (Postfix) with ESMTPSA id CC29E441A0; Tue, 25 Mar 2025 12:36:44 +0000 (UTC) Message-ID: <3a7a92e9-8106-4068-915d-beab62308484@ghiti.fr> Date: Tue, 25 Mar 2025 13:36:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 0/9] Merge arm64/riscv hugetlbfs contpte support Content-Language: en-US To: Christophe Leroy , Alexandre Ghiti , Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Matthew Wilcox , Paul Walmsley , Palmer Dabbelt , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-mm@kvack.org References: <20250321130635.227011-1-alexghiti@rivosinc.com> <1b0d0513-9d18-4603-91e9-20af36334145@csgroup.eu> From: Alexandre Ghiti In-Reply-To: <1b0d0513-9d18-4603-91e9-20af36334145@csgroup.eu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdduiedvieejucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefkffggfgfuvfhfhfgjtgfgsehtkeertddtvdejnecuhfhrohhmpeetlhgvgigrnhgurhgvucfihhhithhiuceorghlvgigsehghhhithhirdhfrheqnecuggftrfgrthhtvghrnhepheevhfevteehhefhueekiedtheeuvdfgieetteetudffgeegieegieeitdevgeelnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghdpihhnfhhrrgguvggrugdrohhrghenucfkphepfedurdefvddrkedurddukeejnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepfedurdefvddrkedurddukeejpdhhvghloheplgduledvrdduieekrddvuddrvdehngdpmhgrihhlfhhrohhmpegrlhgvgiesghhhihhtihdrfhhrpdhnsggprhgtphhtthhopedugedprhgtphhtthhopegthhhrihhsthhophhhvgdrlhgvrhhohiestghsghhrohhuphdrvghupdhrtghpthhtoheprghlvgigghhhihhtihesrhhivhhoshhinhgtrdgtohhmpdhrtghpthhtoheptggrthgrlhhinhdrmhgrrhhinhgrshesrghrmhdrtghomhdprhgtphhtthhopeifihhllheskhgvrhhnvghlrdhorhhgpdhrtghpthhtoheprhihrghnr dhrohgsv ghrthhssegrrhhmrdgtohhmpdhrtghpthhtohepmhgrrhhkrdhruhhtlhgrnhgusegrrhhmrdgtohhmpdhrtghpthhtohepfihilhhlhiesihhnfhhrrgguvggrugdrohhrghdprhgtphhtthhopehprghulhdrfigrlhhmshhlvgihsehsihhfihhvvgdrtghomh X-GND-Sasl: alex@ghiti.fr X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E58FB1C0002 X-Stat-Signature: itok93kg7odhx5phnxgw6c54oh8a1ei6 X-HE-Tag: 1742906214-682279 X-HE-Meta: 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 S9nE0Ro3 UtoLf2zdjx8ATOnrWh+a4hr64nkOqZDZFSnW9563p36qvII530phGecnKanymLhLAF6ff9G9Kbl+nJY5p1Ip+YK7kFTfeUh7PumIsyCmvzoX8gpGJGqCw4WxAEGdYKAHW5MnRaO5MyHC8eyseEASIZYK8W3mM2sDvjk9/aKJ2/qWk3SDrCSu2wuYBLDdD5JL9oJzc/7zPRxN+sjLP46t2Y6a+XOCBXp0Qqrnl+/lxRV+HkFfSXnqq4iraoTR6JzAUTkep9/k3na8TOGjJwO71OZqCiTSksTFa1M0qq9T37ZpTG5z6m8s+JuukGw== 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: Hi Christophe, On 21/03/2025 18:24, Christophe Leroy wrote: > > > Le 21/03/2025 à 14:06, Alexandre Ghiti a écrit : >> This patchset intends to merge the contiguous ptes hugetlbfs >> implementation >> of arm64 and riscv. > > Can we also add powerpc in the dance ? > > powerpc also use contiguous PTEs allthough there is not (yet) a > special name for it: > - b250c8c08c79 powerpc/8xx: Manage 512k huge pages as standard pages > - e47168f3d1b1 powerpc/8xx: Support 16k hugepages with 4k pages > > powerpc also use configuous PMDs/PUDs for larger hugepages: > - 57fb15c32f4f ("powerpc/64s: use contiguous PMD/PUD instead of HUGEPD") > - 7c44202e3609 ("powerpc/e500: use contiguous PMD instead of hugepd") > - 0549e7666373 ("powerpc/8xx: rework support for 8M pages using > contiguous PTE entries") So I have been looking at the powerpc hugetlb implementation and I have to admit that I'm struggling to find similarities with how arm64 and riscv deal with contiguous pte mappings. I think the 2 main characteristics of contpte (arm64) and svnapot (riscv) are the break-before-make requirement and the HW A/D update on only a single pte. Those make the handling of hugetlb pages very similar between arm64 and riscv. But I may have missed something, the powerpc hugetlb implementation is quite "scattered" because of the radix/hash page table and 32/64 bit. Thanks, Alex > > Christophe > >> >> Both arm64 and riscv support the use of contiguous ptes to map pages >> that >> are larger than the default page table size, respectively called contpte >> and svnapot. >> >> The riscv implementation differs from the arm64's in that the LSBs of >> the >> pfn of a svnapot pte are used to store the size of the mapping, allowing >> for future sizes to be added (for now only 64KB is supported). That's an >> issue for the core mm code which expects to find the *real* pfn a pte >> points >> to. Patch 1 fixes that by always returning svnapot ptes with the real >> pfn >> and restores the size of the mapping when it is written to a page table. >> >> The following patches are just merges of the 2 different implementations >> that currently exist in arm64 and riscv which are very similar. It paves >> the way to the reuse of the recent contpte THP work by Ryan [1] to avoid >> reimplementing the same in riscv. >> >> This patchset was tested by running the libhugetlbfs testsuite with 64KB >> and 2MB pages on both architectures (on a 4KB base page size arm64 >> kernel). >> >> [1] >> https://lore.kernel.org/linux-arm-kernel/20240215103205.2607016-1-ryan.roberts@arm.com/ >> >> v4: >> https://lore.kernel.org/linux-riscv/20250127093530.19548-1-alexghiti@rivosinc.com/ >> v3: >> https://lore.kernel.org/all/20240802151430.99114-1-alexghiti@rivosinc.com/ >> v2: >> https://lore.kernel.org/linux-riscv/20240508113419.18620-1-alexghiti@rivosinc.com/ >> v1: >> https://lore.kernel.org/linux-riscv/20240301091455.246686-1-alexghiti@rivosinc.com/ >> >> Changes in v5: >>    - Fix "int i" unused variable in patch 2 (as reported by PW) >>    - Fix !svnapot build >>    - Fix arch_make_huge_pte() which returned a real napot pte >>    - Make __ptep_get(), ptep_get_and_clear() and __set_ptes() napot >> aware to >>      avoid leaking real napot pfns to core mm >>    - Fix arch_contpte_get_num_contig() that used to always try to get >> the >>      mapping size from the ptep, which does not work if the ptep >> comes the core mm >>    - Rebase on top of 6.14-rc7 + fix for >>      huge_ptep_get_and_clear()/huge_pte_clear() >> https://lore.kernel.org/linux-riscv/20250317072551.572169-1-alexghiti@rivosinc.com/ >> >> Changes in v4: >>    - Rebase on top of 6.13 >> >> Changes in v3: >>    - Split set_ptes and ptep_get into internal and external API (Ryan) >>    - Rename ARCH_HAS_CONTPTE into ARCH_WANT_GENERAL_HUGETLB_CONTPTE >> so that >>      we split hugetlb functions from contpte functions (actually >> riscv contpte >>      functions to support THP will come into another series) (Ryan) >>    - Rebase on top of 6.11-rc1 >> >> Changes in v2: >>    - Rebase on top of 6.9-rc3 >> >> Alexandre Ghiti (9): >>    riscv: Safely remove huge_pte_offset() when manipulating NAPOT ptes >>    riscv: Restore the pfn in a NAPOT pte when manipulated by core mm >> code >>    mm: Use common huge_ptep_get() function for riscv/arm64 >>    mm: Use common set_huge_pte_at() function for riscv/arm64 >>    mm: Use common huge_pte_clear() function for riscv/arm64 >>    mm: Use common huge_ptep_get_and_clear() function for riscv/arm64 >>    mm: Use common huge_ptep_set_access_flags() function for riscv/arm64 >>    mm: Use common huge_ptep_set_wrprotect() function for riscv/arm64 >>    mm: Use common huge_ptep_clear_flush() function for riscv/arm64 >> >>   arch/arm64/Kconfig                  |   1 + >>   arch/arm64/include/asm/hugetlb.h    |  22 +-- >>   arch/arm64/include/asm/pgtable.h    |  68 ++++++- >>   arch/arm64/mm/hugetlbpage.c         | 294 +--------------------------- >>   arch/riscv/Kconfig                  |   1 + >>   arch/riscv/include/asm/hugetlb.h    |  36 +--- >>   arch/riscv/include/asm/pgtable-64.h |  11 ++ >>   arch/riscv/include/asm/pgtable.h    | 222 ++++++++++++++++++--- >>   arch/riscv/mm/hugetlbpage.c         | 243 +---------------------- >>   arch/riscv/mm/pgtable.c             |   6 +- >>   include/linux/hugetlb_contpte.h     |  39 ++++ >>   mm/Kconfig                          |   3 + >>   mm/Makefile                         |   1 + >>   mm/hugetlb_contpte.c                | 258 ++++++++++++++++++++++++ >>   14 files changed, 583 insertions(+), 622 deletions(-) >>   create mode 100644 include/linux/hugetlb_contpte.h >>   create mode 100644 mm/hugetlb_contpte.c >> > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv