From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 740A5C25B74 for ; Fri, 10 May 2024 13:50:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3NCsapV2WE5waGpR/T+4wDnkV0nTO8QfkIhtbLC2BR0=; b=hMQTf1mvRRYTUL Jf8aQ3eWgGGmDEqvL8OyqhwFIKzVJoKVeu2XMz3WR0TLDv99C4HvMD/Cjs6CeAaHDXebSDdtoiZhE 5rceIqTZw7NYGuY43nax4BQmZC9swEMoRLgxDLm8NPpX3AhZfsJH2fmsbr3h7DjOlViG+ghSA4Yc0 yfep5y/46PAOv5NVvIhxt4mQRjzV3A0v9/O+1cleUGgPSNtUJSOw9kji5oGHQqVL9J11edMUYnekB Ivk9Iho72cKDKTpufe9bsMqNH5FiOpcSZlP1Ysyxduj28TF99qlxVgDLEJ3T7pGO6QXrl6y0JFlcs SHA8JlH2uf+DpLP/zGQQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s5QdU-00000005RoT-3xfI; Fri, 10 May 2024 13:50:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s5QdO-00000005Rmc-4BXH; Fri, 10 May 2024 13:50:05 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 04CFE106F; Fri, 10 May 2024 06:50:23 -0700 (PDT) Received: from [10.57.65.1] (unknown [10.57.65.1]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 02C483F641; Fri, 10 May 2024 06:49:55 -0700 (PDT) Message-ID: <6d37f914-d139-48ea-be63-c428ac767cc1@arm.com> Date: Fri, 10 May 2024 14:49:54 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RESEND v2 0/9] Merge arm64/riscv hugetlbfs contpte support Content-Language: en-GB To: Alexandre Ghiti , Catalin Marinas , Will Deacon , Mark Rutland , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-mm@kvack.org References: <20240508113419.18620-1-alexghiti@rivosinc.com> From: Ryan Roberts In-Reply-To: <20240508113419.18620-1-alexghiti@rivosinc.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240510_065003_454739_C3EDCEBD X-CRM114-Status: GOOD ( 28.48 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On 08/05/2024 12:34, Alexandre Ghiti wrote: > This patchset intends to merge the contiguous ptes hugetlbfs implementation > of arm64 and riscv. > > 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. Hi Alexandre, I've skimmed through this series and the one that moves contpte. I can see there is definitely value in sharing the implementation, and the rough shape of things seems appropriate. I had some minor concerns about making it harder to implement potential future arm64 errata workarounds but on reflection, most of the now-shared code is really just wrapping the primitives that are still arch-specific. I'm going to need to spend proper time reviewing it to give detailed feedback, but I'll be out on paternity leave for 3 weeks from end of Monday at the latest. So realistically I won't be able to do the detailed review until at least the first week of June. Some high level thoughts: - huge_ptep_* functions could be working on different sized huge ptes - arm64 supports contpte, pmd, contpmd and pud. Is keeping them in contpte.c appropriate? Perhaps it's better to keep huge_pte and contpte separate? Also, it only works on arm64 because we can get away with calling the lower-level pte functions even when the huge_pte is actually a contpmd/pmd/pud, because the format is the same. That might present challenges to other arches if the format is different? - It might be easier to review if the arm64 stuff is first moved (without changes) then modified to make it suitable for riscv, then for riscv to be hooked up. At the moment I'm trying to follow all 3 parts per-function. Thanks, Ryan > > 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/ > > Changes in v2: > - Rebase on top of 6.9-rc3 > > Alexandre Ghiti (9): > riscv: Restore the pfn in a NAPOT pte when manipulated by core mm code > riscv: Safely remove huge_pte_offset() when manipulating NAPOT ptes > 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/pgtable.h | 56 +++++- > arch/arm64/mm/hugetlbpage.c | 291 +--------------------------- > arch/riscv/Kconfig | 1 + > arch/riscv/include/asm/hugetlb.h | 2 +- > arch/riscv/include/asm/pgtable-64.h | 11 ++ > arch/riscv/include/asm/pgtable.h | 153 +++++++++++++-- > arch/riscv/mm/hugetlbpage.c | 227 ---------------------- > arch/riscv/mm/pgtable.c | 6 +- > mm/Kconfig | 3 + > mm/Makefile | 1 + > mm/contpte.c | 272 ++++++++++++++++++++++++++ > 12 files changed, 480 insertions(+), 544 deletions(-) > create mode 100644 mm/contpte.c > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv