From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B2F5818EFD1 for ; Wed, 21 May 2025 14:14:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747836868; cv=none; b=MWS3MYAsJKDwuwTVY7ZbIlRMOGlbbzwDSTOGDDG9HKXQIjet/+ld0ogLvGzIjnC/9B9PqPp6sgLcMRyMlcq0HOu4PvMcbdDumcaY4h5WsExs5l6+7hJ6mWb0o6BSPIE07Zw3eL/Fs27F/+rckaTR0qhp/oT+a3X8tDPa15iXLKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747836868; c=relaxed/simple; bh=IoxOUjr6fXQzKKredPLraY17208/esIaeSVKNDzenVs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MMiGc79sOgPGHjB6GLLhK6QzwSot8D7U/8oL4tIdoFssQOlYvKaj+eFwbIZhW39DIi3y2nDGs01r1RQlg58SUOfqX+4O8TjORBsu3X/7zzafvSSD4XJHuF3Eeh1nKAio4cCrQmOFCrK7BCrdKSH/Yr5P5cIWQzO0o2zc1J5l15E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 267E11515; Wed, 21 May 2025 07:14:12 -0700 (PDT) Received: from [10.57.94.227] (unknown [10.57.94.227]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4C36F3F5A1; Wed, 21 May 2025 07:14:22 -0700 (PDT) Message-ID: Date: Wed, 21 May 2025 15:14:20 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/5] arm64: Add batched version of ptep_modify_prot_start Content-Language: en-GB To: Dev Jain , akpm@linux-foundation.org Cc: 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, anshuman.khandual@arm.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, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com References: <20250519074824.42909-1-dev.jain@arm.com> <20250519074824.42909-5-dev.jain@arm.com> From: Ryan Roberts In-Reply-To: <20250519074824.42909-5-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 19/05/2025 08:48, Dev Jain wrote: > Override the generic definition to use get_and_clear_full_ptes(). This helper > does a TLBI only for the starting and ending contpte block of the range, whereas > the current implementation will call ptep_get_and_clear() for every contpte block, > thus doing a TLBI on every contpte block. Therefore, we have a performance win. > The arm64 definition of pte_accessible() allows us to batch around it in clear_flush_ptes(): > #define pte_accessible(mm, pte) \ > (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte)) > > All ptes are obviously present in the folio batch, and they are also valid. > > Signed-off-by: Dev Jain Please squash this with the > --- > 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); > +} I think we can do this more precisely with respect to tlbis and also without needing to create a new clear_flush_ptes() helper: pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, unsigned int nr) { pte_t pte = get_and_clear_full_ptes(vma->vm_mm, addr, ptep, nr, 0); if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) { /* * Break-before-make (BBM) is required for all user space mappings * when the permission changes from executable to non-executable * in cases where cpu is affected with errata #2645198. */ if (pte_accessible(vma->vm_mm, pte) && pte_user_exec(pte)) __flush_tlb_range(vma, addr, nr * PAGE_SIZE, PAGE_SIZE, true, 3); } return pte; } > + > +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 e40ed57e034d..41f4a8de5c28 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; > } Let's not create a new generic helper if only arm64 is using it. We would also want to add a doc header to describe this helper. My proposal avoids this. Thanks, Ryan > + > +#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