From nobody Sun Feb 8 06:53:59 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0FF2A149DE0 for ; Wed, 27 Mar 2024 19:07:40 +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=1711566463; cv=none; b=CVaKiBlXkhDl0pEEeL2Lc1bnvJ7VfiBWuGbKA398BMLZAhdDBrZ7zvw/JhIlvjrC6R8d1FEL3Hm6aT/WF6I92DeJbyOZkPw+Ct2f3ndsbaNGPhzL8M49UEmQnuFypzaGWw8WohobtMCTuNMJfmJNmL4gIAjihQpszaTjtDxXqLw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711566463; c=relaxed/simple; bh=RMXDDjZrf8/faa23V77RsUn8dZUjE2GprXeV9v/wvbY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=EK504K9y9UJY01eHN3c+6GBSmvLXmr8n/xsDepKukcls4JudwpGNQuDRBPLK0k8jZHDf/g52gxGivkS2kkeRhLjRehjvg/XFveXUgKykaBrAjPUwtgNWGnPZa6XdljXoWf3vWOW+jBsfe4+ljgL1pRbKRY9kLLCcm/AkR6fSQ6I= 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 7D45C2F4; Wed, 27 Mar 2024 12:08:12 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F1BA63F694; Wed, 27 Mar 2024 12:07:36 -0700 (PDT) From: Ryan Roberts To: Catalin Marinas , Will Deacon , Mark Rutland , Ard Biesheuvel , David Hildenbrand , Donald Dutile , Eric Chanudet Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v1] arm64: mm: Batch dsb and isb when populating pgtables Date: Wed, 27 Mar 2024 19:07:23 +0000 Message-Id: <20240327190723.185232-1-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240326101448.3453626-1-ryan.roberts@arm.com> References: <20240326101448.3453626-1-ryan.roberts@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" After removing uneccessary TLBIs, the next bottleneck when creating the page tables for the linear map is DSB and ISB, which were previously issued per-pte in __set_pte(). Since we are writing multiple ptes in a given pte table, we can elide these barriers and insert them once we have finished writing to the table. Signed-off-by: Ryan Roberts --- arch/arm64/include/asm/pgtable.h | 7 ++++++- arch/arm64/mm/mmu.c | 13 ++++++++++++- 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgta= ble.h index bd5d02f3f0a3..81e427b23b3f 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -271,9 +271,14 @@ static inline pte_t pte_mkdevmap(pte_t pte) return set_pte_bit(pte, __pgprot(PTE_DEVMAP | PTE_SPECIAL)); } -static inline void __set_pte(pte_t *ptep, pte_t pte) +static inline void ___set_pte(pte_t *ptep, pte_t pte) { WRITE_ONCE(*ptep, pte); +} + +static inline void __set_pte(pte_t *ptep, pte_t pte) +{ + ___set_pte(ptep, pte); /* * Only if the new pte is valid and kernel, otherwise TLB maintenance diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 1b2a2a2d09b7..c6d5a76732d4 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -301,7 +301,11 @@ static pte_t *init_pte(pte_t *ptep, unsigned long addr= , unsigned long end, do { pte_t old_pte =3D __ptep_get(ptep); - __set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot)); + /* + * Required barriers to make this visible to the table walker + * are deferred to the end of alloc_init_cont_pte(). + */ + ___set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot)); /* * After the PTE entry has been populated once, we @@ -358,6 +362,13 @@ static void alloc_init_cont_pte(pmd_t *pmdp, unsigned = long addr, } while (addr =3D next, addr !=3D end); ops->unmap(TYPE_PTE); + + /* + * Ensure all previous pgtable writes are visible to the table walker. + * See init_pte(). + */ + dsb(ishst); + isb(); } static pmd_t *init_pmd(pmd_t *pmdp, unsigned long addr, unsigned long end, -- 2.25.1