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 CE77323B60B for ; Mon, 30 Jun 2025 10:43:29 +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=1751280211; cv=none; b=TVhoeapLu/gbHB3D87cYbaY8Cz55iGD1FY2MfB8n5Oux5FE+E7IQlHfRsbkhzYCnTS0nPOrguLfvGFteA+9LqzPiEI1s9nJ+gndKUEWgvg6lSpRFizjSaNRvxsRT/0//wXZTX5jc+3tJFc15VpANDA6udAgj8teG8zfmaLVaTHM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751280211; c=relaxed/simple; bh=NMq1qdal3K1Txw8VMIjXXOG92KdCcYJ6FQYEtNaZEhQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HZnW5PN8iAudzEtngEVu/qLN2P27SqeZNvluo43YI4x/1XnKuvDMgz0zHBiyCrzonS8TQLtExS2S9qhaz6ZX5OwILqMeaxFNxOtM6E3BcjWE/FUwKbe2wWKolfr0Y+wOWf7YbE4PNmMDgPKZY1HbALf03nI/n29Zn3da8ARfc64= 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 1EE991D34; Mon, 30 Jun 2025 03:43:13 -0700 (PDT) Received: from [10.1.34.165] (XHFQ2J9959.cambridge.arm.com [10.1.34.165]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0E6C53F58B; Mon, 30 Jun 2025 03:43:24 -0700 (PDT) Message-ID: <051d5338-d073-4a92-abd2-c68367c17636@arm.com> Date: Mon, 30 Jun 2025 11:43:23 +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 v4 4/4] arm64: Add batched versions of ptep_modify_prot_start/commit 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: <20250628113435.46678-1-dev.jain@arm.com> <20250628113435.46678-5-dev.jain@arm.com> From: Ryan Roberts In-Reply-To: <20250628113435.46678-5-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 28/06/2025 12:34, Dev Jain wrote: > Override the generic definition of modify_prot_start_ptes() 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 in the > errata specific case: > > #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. > > Override the generic definition of modify_prot_commit_ptes() to simply > use set_ptes() to map the new ptes into the pagetable. > > Signed-off-by: Dev Jain Reviewed-by: Ryan Roberts > --- > arch/arm64/include/asm/pgtable.h | 10 ++++++++++ > arch/arm64/mm/mmu.c | 28 +++++++++++++++++++++++----- > 2 files changed, 33 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index ba63c8736666..abd2dee416b3 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -1643,6 +1643,16 @@ 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); > + > +#define modify_prot_commit_ptes modify_prot_commit_ptes > +extern void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr, > + pte_t *ptep, pte_t old_pte, pte_t pte, > + unsigned int nr); > + > #ifdef CONFIG_ARM64_CONTPTE > > /* > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 3d5fb37424ab..38325616f467 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -26,6 +26,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1524,24 +1525,41 @@ 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) > { > + 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_user_exec(ptep_get(ptep))) > - return ptep_clear_flush(vma, addr, ptep); > + if (pte_accessible(vma->vm_mm, pte) && pte_user_exec(pte)) > + __flush_tlb_range(vma, addr, nr * PAGE_SIZE, > + PAGE_SIZE, true, 3); > } > - return ptep_get_and_clear(vma->vm_mm, addr, ptep); > + > + 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 modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr, > + pte_t *ptep, pte_t old_pte, pte_t pte, > + unsigned int nr) > +{ > + set_ptes(vma->vm_mm, addr, ptep, pte, nr); > } > > void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, > pte_t old_pte, pte_t pte) > { > - set_pte_at(vma->vm_mm, addr, ptep, pte); > + modify_prot_commit_ptes(vma, addr, ptep, old_pte, pte, 1); > } > > /*