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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9067C02194 for ; Fri, 7 Feb 2025 11:20:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 726ED280004; Fri, 7 Feb 2025 06:20:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6D746280001; Fri, 7 Feb 2025 06:20:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5A034280004; Fri, 7 Feb 2025 06:20:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 3E461280001 for ; Fri, 7 Feb 2025 06:20:42 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id CF146161814 for ; 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imf23.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf23.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1738927240; a=rsa-sha256; cv=none; b=KnJgeMxB9XFBqnb/YpKR0Zpmy+Fzke56zkhRvDjM2t6znyHxkIXl2DlRJgCpIHMTvFTlUx +CAdeiKt+3Qrjc0XfyYx7sn/4y+zbe9b2hTapuJuKQ205F+wquO6o/gUuAXx9YHhdPyeiQ CQRANAV2JcX/t3O5CILglFifcYvPUzY= 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 31571113E; Fri, 7 Feb 2025 03:21:02 -0800 (PST) Received: from [10.57.81.111] (unknown [10.57.81.111]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 51F5E3F63F; Fri, 7 Feb 2025 03:20:36 -0800 (PST) Message-ID: <21da59a8-165d-4423-a00d-d5859f42ec11@arm.com> Date: Fri, 7 Feb 2025 11:20:34 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 12/16] arm64/mm: Support huge pte-mapped pages in vmap Content-Language: en-GB To: Anshuman Khandual , Catalin Marinas , Will Deacon , Muchun Song , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Mark Rutland , Ard Biesheuvel , Dev Jain , Alexandre Ghiti , Steve Capper , Kevin Brodsky Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250205151003.88959-1-ryan.roberts@arm.com> <20250205151003.88959-13-ryan.roberts@arm.com> <9a0d3009-18fc-4b53-941a-b6d830fce36a@arm.com> From: Ryan Roberts In-Reply-To: <9a0d3009-18fc-4b53-941a-b6d830fce36a@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 4mrf8hidnsrcodp6875xf5j4aq7d613f X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 18EF614000A X-HE-Tag: 1738927239-764013 X-HE-Meta: U2FsdGVkX1/84nZGjqBonR6UnUtTx8x5lYXr7BwVyW+8qg6HkTRXwyYEqekiC43vXZFJfz8mhOWY9/uoFTCvPm9hm+/GbLXrFIGydMskQ2rvcnkKdHl2MMetjJ1OeHoX9pv7Mt9CNj0b7bLMgIgK7GxjogqzUjSCuBp0JR8NcqFchQmgtH5WMAs8LnofeBAyYZvUgMmxe76+C+r4wt4UDEMkv32hN57b3EqVB8+EGBPp/df3A7J7MfrJbTznjhv7XXv7XqZGlovVPeqLMis1tBcOFJ13Zu1KhDoAlAhWSO0Ol7Lz3wxdTViv6IkNwfD3ekIT8uqSv+bbLkZhjYzklaR84ysgyeeXNU/unKhjmuefrI+KTT7/CBkrN1ediPhB1PM3o4z54soUTvnlBbfi1JJ2BKcL5+i7117Vj6KBJ5PDwNfAGqDBN3SeOJkF5jBPPqEV2bbAjH0edIHWVVqrQCmZuWYUdULGCoGtFrIEW1jaLLV653++vDbJnMZQZZQKiIBnqhqBIO6we5himUtue72ymsXOCHqmCN6+arVHtvboWeqzCfpIAXZzX04730lHbR9FZGnbkxSvtaMIu/WeovfWuvektpT7hDU6ok7f7Uh40a7CcMJdO2fZWFlFG6ldsZRLj2ivQu23HPsM7uXGMq8TpZKBe9Sm8jcBh1Fu+xqO6bKY0VWLmd7reuVklBKNb3j6Twz9Jmw2IXyZUtROBq/gQelSdz0f/cY/IKp5fXMs/y+MVvTVa+C2yYH6gonrOBg69XrCYj6E9yeiJK2p6aIEQKIU8gKrHTC7UHlBCeZOo6Qxr8FgOnNgdd85xYYH0xmrT7QN0i3nUaE0Vif/Kn1h1bpC9T4PpDj3j1zLZq0u43t1Oi037LRwxMWBo3T4voUad7ZG7Zrv1vGpCcTsoTg185XpiJpzFxByMDV2BX75Du/yT1fvh81XugvvmMBuEtNl+rANalifldPxu+7 +E3uQW78 5ZYYciR/r15aR1B94tKcPuFOgtnIyhRmEPSwj8Avz9VAxuKCVbD7hTf7Nue6XFvXuYX1leLqzwUPDvtRtkB37jlfwXxhTdqsLemUSyI49CeVJt6txqobZffoKjFteifnZIZNorKiuzZHBZTpqDOJjJfFAba+JcwBWjCvOnCZPeN+GLkck1vgwWldXeo+MpDjFccEDggs1Mou7zIJ1elXrcKnNiUhGgP0bXhYyjbpRU5wu2Mstfh7uAowsHA== 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: On 07/02/2025 10:04, Anshuman Khandual wrote: > > > On 2/5/25 20:39, Ryan Roberts wrote: >> Implement the required arch functions to enable use of contpte in the >> vmap when VM_ALLOW_HUGE_VMAP is specified. This speeds up vmap >> operations due to only having to issue a DSB and ISB per contpte block >> instead of per pte. But it also means that the TLB pressure reduces due >> to only needing a single TLB entry for the whole contpte block. > > Right. > >> >> Since vmap uses set_huge_pte_at() to set the contpte, that API is now >> used for kernel mappings for the first time. Although in the vmap case >> we never expect it to be called to modify a valid mapping so >> clear_flush() should never be called, it's still wise to make it robust >> for the kernel case, so amend the tlb flush function if the mm is for >> kernel space. > > Makes sense. > >> >> Tested with vmalloc performance selftests: >> >> # kself/mm/test_vmalloc.sh \ >> run_test_mask=1 >> test_repeat_count=5 >> nr_pages=256 >> test_loop_count=100000 >> use_huge=1 >> >> Duration reduced from 1274243 usec to 1083553 usec on Apple M2 for 15% >> reduction in time taken. >> >> Signed-off-by: Ryan Roberts >> --- >> arch/arm64/include/asm/vmalloc.h | 40 ++++++++++++++++++++++++++++++++ >> arch/arm64/mm/hugetlbpage.c | 5 +++- >> 2 files changed, 44 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/include/asm/vmalloc.h b/arch/arm64/include/asm/vmalloc.h >> index 38fafffe699f..fbdeb40f3857 100644 >> --- a/arch/arm64/include/asm/vmalloc.h >> +++ b/arch/arm64/include/asm/vmalloc.h >> @@ -23,6 +23,46 @@ static inline bool arch_vmap_pmd_supported(pgprot_t prot) >> return !IS_ENABLED(CONFIG_PTDUMP_DEBUGFS); >> } >> >> +#define arch_vmap_pte_range_map_size arch_vmap_pte_range_map_size >> +static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr, >> + unsigned long end, u64 pfn, >> + unsigned int max_page_shift) >> +{ >> + if (max_page_shift < CONT_PTE_SHIFT) >> + return PAGE_SIZE; >> + >> + if (end - addr < CONT_PTE_SIZE) >> + return PAGE_SIZE; >> + >> + if (!IS_ALIGNED(addr, CONT_PTE_SIZE)) >> + return PAGE_SIZE; >> + >> + if (!IS_ALIGNED(PFN_PHYS(pfn), CONT_PTE_SIZE)) >> + return PAGE_SIZE; >> + >> + return CONT_PTE_SIZE; > > A small nit: > > Should the rationale behind picking CONT_PTE_SIZE be added here as an in code > comment or something in the function - just to make things bit clear. I'm not sure what other size we would pick? > >> +} >> + >> +#define arch_vmap_pte_range_unmap_size arch_vmap_pte_range_unmap_size >> +static inline unsigned long arch_vmap_pte_range_unmap_size(unsigned long addr, >> + pte_t *ptep) >> +{ >> + /* >> + * The caller handles alignment so it's sufficient just to check >> + * PTE_CONT. >> + */ >> + return pte_valid_cont(__ptep_get(ptep)) ? CONT_PTE_SIZE : PAGE_SIZE; > > I guess it is safe to query the CONT_PTE from the mapped entry itself. Yes I don't see why not. Is there some specific aspect you're concerned about? > >> +} >> + >> +#define arch_vmap_pte_supported_shift arch_vmap_pte_supported_shift >> +static inline int arch_vmap_pte_supported_shift(unsigned long size) >> +{ >> + if (size >= CONT_PTE_SIZE) >> + return CONT_PTE_SHIFT; >> + >> + return PAGE_SHIFT; >> +} >> + >> #endif >> >> #define arch_vmap_pgprot_tagged arch_vmap_pgprot_tagged >> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c >> index 02afee31444e..a74e43101dad 100644 >> --- a/arch/arm64/mm/hugetlbpage.c >> +++ b/arch/arm64/mm/hugetlbpage.c >> @@ -217,7 +217,10 @@ static void clear_flush(struct mm_struct *mm, >> for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) >> ___ptep_get_and_clear(mm, ptep, pgsize); >> >> - __flush_hugetlb_tlb_range(&vma, saddr, addr, pgsize, true); >> + if (mm == &init_mm) >> + flush_tlb_kernel_range(saddr, addr); >> + else >> + __flush_hugetlb_tlb_range(&vma, saddr, addr, pgsize, true); >> } >> >> void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, > > Otherwise LGTM. > > Reviewed-by: Anshuman Khandual Thanks!