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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 4B517C48BEF for ; Thu, 15 Feb 2024 10:33:27 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TbBH95fNkz3dW4 for ; Thu, 15 Feb 2024 21:33:25 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=ryan.roberts@arm.com; receiver=lists.ozlabs.org) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4TbBGc5VjTz3c96 for ; Thu, 15 Feb 2024 21:32:54 +1100 (AEDT) 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 40DFDDA7; Thu, 15 Feb 2024 02:33:04 -0800 (PST) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3722C3F7B4; Thu, 15 Feb 2024 02:32:20 -0800 (PST) From: Ryan Roberts To: Catalin Marinas , Will Deacon , Ard Biesheuvel , Marc Zyngier , James Morse , Andrey Ryabinin , Andrew Morton , Matthew Wilcox , Mark Rutland , David Hildenbrand , Kefeng Wang , John Hubbard , Zi Yan , Barry Song <21cnbao@gmail.com>, Alistair Popple , Yang Shi , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH v6 01/18] mm: Clarify the spec for set_ptes() Date: Thu, 15 Feb 2024 10:31:48 +0000 Message-Id: <20240215103205.2607016-2-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240215103205.2607016-1-ryan.roberts@arm.com> References: <20240215103205.2607016-1-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ryan Roberts , x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" set_ptes() spec implies that it can only be used to set a present pte because it interprets the PFN field to increment it. However, set_pte_at() has been implemented on top of set_ptes() since set_ptes() was introduced, and set_pte_at() allows setting a pte to a not-present state. So clarify the spec to state that when nr==1, new state of pte may be present or not present. When nr>1, new state of all ptes must be present. While we are at it, tighten the spec to set requirements around the initial state of ptes; when nr==1 it may be either present or not-present. But when nr>1 all ptes must initially be not-present. All set_ptes() callsites already conform to this requirement. Stating it explicitly is useful because it allows for a simplification to the upcoming arm64 contpte implementation. Acked-by: David Hildenbrand Signed-off-by: Ryan Roberts --- include/linux/pgtable.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 49ab1f73b5c2..231370e1b80f 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -229,6 +229,10 @@ static inline pte_t pte_next_pfn(pte_t pte) * @pte: Page table entry for the first page. * @nr: Number of pages to map. * + * When nr==1, initial state of pte may be present or not present, and new state + * may be present or not present. When nr>1, initial state of all ptes must be + * not present, and new state must be present. + * * May be overridden by the architecture, or the architecture can define * set_pte() and PFN_PTE_SHIFT. * -- 2.25.1