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 B27311E47CA for ; Wed, 30 Apr 2025 05:43:25 +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=1745991807; cv=none; b=UtD4zCOwu5Efj9LMLFGVHTrh+vtdiMdawI8jbNEy9t0mKooK2d8XzsCmjCmGBuzEBfTB/Mwx5sUJ578Gg3Kb8SJdyUutcSXe/98QQsTQVRic6ORqobRAq1ODUl15pXjL8uRS2Z7JVTW5Wdt2m3xLsukPojKYYakixyjleji4ZbU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745991807; c=relaxed/simple; bh=BBepbYs5c3xF+rGmywv56auWs6yzMNsgKg69D6ethps=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Hl28PFfLSd/5+X09qOSg08Yk2PI9AiJDSm9EayqBBxG8CmOmaLvJMDeOIh3yPWAFBwV3Ib5ELZfjNcBV0KiJMkbhIP16vDUO0LEoxjJNwhw+dXmEoC6rXNATTjKNJ0tsh+ocdBm3c+/gIim23onJ6OCmg8E8AvjzNfWAQ0wPv2w= 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 B1F98106F; Tue, 29 Apr 2025 22:43:17 -0700 (PDT) Received: from [10.163.50.23] (unknown [10.163.50.23]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C9B183F5A1; Tue, 29 Apr 2025 22:43:14 -0700 (PDT) Message-ID: Date: Wed, 30 Apr 2025 11:13:10 +0530 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 v2 4/7] arm64: Add batched version of ptep_modify_prot_start To: Dev Jain , 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: Anshuman Khandual In-Reply-To: <20250429052336.18912-5-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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 ? > > 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