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 D1DFCC369D9 for ; Wed, 30 Apr 2025 06:07:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ijWZ94PEdJ/Gl8UXsp1oF+QtTyP5rdSwXjSmQfL4z54=; b=aQj6rM1hAMyadsRBD9v2JSOSrI VbH1E+LIiHcgIBL7K8olcnGZiHhLZpar1jObJp/MSKO6meOTJHREkVvesU4q36RDIffDeVOdUOkMq GFz/uhdjxLnJMRLokmz9nr2bKk9veKa4QAklzVhMgSX72qnJu7z354Co3JMYaL82VNJTt/ddDGwF9 prQvPvwPMzaLDAfxm4L6vX47FLq1FKv0Bxh8QutbkuSdHZ/HqgdaCH80KwJPdbviMSJy0EJbxskhz lbOz+T5q02DAdsnrSTLg+PFONe8WZfuLoFYGAm9Ymdmc4ZOgfP28Q7n+HEAlCA2OqW83HP1dL63ZE 3RIm7bNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uA0bh-0000000BpL8-1NG1; Wed, 30 Apr 2025 06:07:45 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uA0Kb-0000000BnTd-2x6h for linux-arm-kernel@bombadil.infradead.org; Wed, 30 Apr 2025 05:50:05 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID: Sender:Reply-To:Content-ID:Content-Description; bh=ijWZ94PEdJ/Gl8UXsp1oF+QtTyP5rdSwXjSmQfL4z54=; b=bctz2IQKTpkJMRIe/STUav+1sL XTy0vzI11KUk+xbjeQ4yOkwW7fWuPQn/ALB7Bc3e++wHB1uXFcHh7g93oHXv0fC49Axmnnusy43XT N2VKYTPVVaiseiuMAH69Wyfuh7F6ZV1+COID6FxFNRq6d+1Dmsf8DnMqMTWe0LyKlnduJd0QMYcH2 ZwpGIdfD+yHjh076Y2SolReDtDKeDLqC9zBtYtqKf9knWeBEqMniB5I3lroZt5cBnYnYjacnps9C2 uQFm1MjaVk0JU4g3go/z6Bu9f4w357wLZCCXx+CGoO4cSzK7BgcyIuaIj+6mWK/U6THtVp9PbC9vE UcoPcGxQ==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1uA0KY-0000000DhkC-0Uwu for linux-arm-kernel@lists.infradead.org; Wed, 30 Apr 2025 05:50:04 +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 B3902106F; Tue, 29 Apr 2025 22:49:53 -0700 (PDT) Received: from [10.163.79.251] (unknown [10.163.79.251]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 327DD3F5A1; Tue, 29 Apr 2025 22:49:50 -0700 (PDT) Message-ID: <5eebef24-6c98-4407-a4f1-5a97f08b76a4@arm.com> Date: Wed, 30 Apr 2025 11:19:47 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/7] arm64: Add batched version of ptep_modify_prot_start To: Anshuman Khandual , akpm@linux-foundation.org Cc: ryan.roberts@arm.com, david@redhat.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, peterx@redhat.com, joey.gouly@arm.com, ioworker0@gmail.com, baohua@kernel.org, kevin.brodsky@arm.com, quic_zhenhuah@quicinc.com, christophe.leroy@csgroup.eu, yangyicong@hisilicon.com, linux-arm-kernel@lists.infradead.org, namit@vmware.com, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com References: <20250429052336.18912-1-dev.jain@arm.com> <20250429052336.18912-5-dev.jain@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250430_065002_729684_979311CA X-CRM114-Status: GOOD ( 16.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 30/04/25 11:13 am, Anshuman Khandual wrote: > On 4/29/25 10:53, Dev Jain wrote: >> Override the generic definition to use get_and_clear_full_ptes(), so that >> we do a TLBI possibly only on the "contpte-edges" of the large PTE block, >> instead of doing it for every contpte block, which happens for ptep_get_and_clear(). > > Could you please explain what does "contpte-edges" really signify in the > context of large PTE blocks ? Also how TLBI operation only on these edges > will never run into the risk of missing TLB invalidation of some other > mapped areas ? We are doing a TLBI over the whole range already, in the mprotect code: see tlb_flush_pte_range. What the arm64 internal API does, irrespective of the caller, is to do a TLBI for every contpte block in case of unfolding. We don't need that for the intermediate blocks because the caller does that. We do need a TLBI for the start and end contpte block, because in case the range we are invalidating partially covers them, then the caller will not do a TLBI for the non-overlapped PTEs of the block. I'll explain some more in the changelog next version. > >> >> Signed-off-by: Dev Jain >> --- >> arch/arm64/include/asm/pgtable.h | 5 +++++ >> arch/arm64/mm/mmu.c | 12 +++++++++--- >> include/linux/pgtable.h | 4 ++++ >> mm/pgtable-generic.c | 16 +++++++++++----- >> 4 files changed, 29 insertions(+), 8 deletions(-) >> >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >> index 2a77f11b78d5..8872ea5f0642 100644 >> --- a/arch/arm64/include/asm/pgtable.h >> +++ b/arch/arm64/include/asm/pgtable.h >> @@ -1553,6 +1553,11 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma, >> unsigned long addr, pte_t *ptep, >> pte_t old_pte, pte_t new_pte); >> >> +#define modify_prot_start_ptes modify_prot_start_ptes >> +extern pte_t modify_prot_start_ptes(struct vm_area_struct *vma, >> + unsigned long addr, pte_t *ptep, >> + unsigned int nr); >> + >> #ifdef CONFIG_ARM64_CONTPTE >> >> /* >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 8fcf59ba39db..fe60be8774f4 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1523,7 +1523,8 @@ static int __init prevent_bootmem_remove_init(void) >> early_initcall(prevent_bootmem_remove_init); >> #endif >> >> -pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) >> +pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr, >> + pte_t *ptep, unsigned int nr) >> { >> if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) { >> /* >> @@ -1532,9 +1533,14 @@ pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte >> * in cases where cpu is affected with errata #2645198. >> */ >> if (pte_user_exec(ptep_get(ptep))) >> - return ptep_clear_flush(vma, addr, ptep); >> + return clear_flush_ptes(vma, addr, ptep, nr); >> } >> - return ptep_get_and_clear(vma->vm_mm, addr, ptep); >> + return get_and_clear_full_ptes(vma->vm_mm, addr, ptep, nr, 0); >> +} >> + >> +pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) >> +{ >> + return modify_prot_start_ptes(vma, addr, ptep, 1); >> } >> >> void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, >> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h >> index ed287289335f..10cdb87ccecf 100644 >> --- a/include/linux/pgtable.h >> +++ b/include/linux/pgtable.h >> @@ -828,6 +828,10 @@ extern pte_t ptep_clear_flush(struct vm_area_struct *vma, >> pte_t *ptep); >> #endif >> >> +extern pte_t clear_flush_ptes(struct vm_area_struct *vma, >> + unsigned long address, >> + pte_t *ptep, unsigned int nr); >> + >> #ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH >> extern pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, >> unsigned long address, >> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c >> index 5a882f2b10f9..e238f88c3cac 100644 >> --- a/mm/pgtable-generic.c >> +++ b/mm/pgtable-generic.c >> @@ -90,17 +90,23 @@ int ptep_clear_flush_young(struct vm_area_struct *vma, >> } >> #endif >> >> -#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH >> -pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, >> - pte_t *ptep) >> +pte_t clear_flush_ptes(struct vm_area_struct *vma, unsigned long address, >> + pte_t *ptep, unsigned int nr) >> { >> struct mm_struct *mm = (vma)->vm_mm; >> pte_t pte; >> - pte = ptep_get_and_clear(mm, address, ptep); >> + pte = get_and_clear_full_ptes(mm, address, ptep, nr, 0); >> if (pte_accessible(mm, pte)) >> - flush_tlb_page(vma, address); >> + flush_tlb_range(vma, address, address + nr * PAGE_SIZE); >> return pte; >> } >> + >> +#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH >> +pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, >> + pte_t *ptep) >> +{ >> + return clear_flush_ptes(vma, address, ptep, 1); >> +} >> #endif >> >> #ifdef CONFIG_TRANSPARENT_HUGEPAGE