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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 F027CF36BA4 for ; Fri, 10 Apr 2026 03:22:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=HHdIs+WY6R5DaoZ/DJBQW/O2KE9/mI5VCbJg5HKZ1ms=; b=UPS4Df+GemWlGl1bciluNkPlHx SvXQ8I4ugh7AZMo5L+fMGDywrqMCtsPL2SGEsSeZHK7AUTx6zowWlXEZIIQis8W2nzreKEjuIJpqS FMGLHKf05hYeqS1VulyyEgIs4O4deSAzdHAZ8c+aZy0PIdcrpy5SfvaqsQzsyo2sfomoJjAnSmrIw 9EBA0W8oJ5zD00Lbw2UPWWL2169Xb3biXB6DW/MFSRXjBHx2NTQeAB4ScGXHyPXqD23dUBTIGo+qw F+iDZhLm6s+9yZ2k0HfXAMQPw6/GAmjT41t7eGSNpzEDx45t9s2e+J+N5mVWz4NaNd3bw3iGJxOdp 1/bE9lkQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wB2SH-0000000BXEW-0aoJ; Fri, 10 Apr 2026 03:22:49 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wB2SE-0000000BXEB-2A7j for linux-arm-kernel@lists.infradead.org; Fri, 10 Apr 2026 03:22:48 +0000 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 EB3061C25; Thu, 9 Apr 2026 20:22:36 -0700 (PDT) Received: from [10.163.181.107] (unknown [10.163.181.107]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AEDB83F641; Thu, 9 Apr 2026 20:22:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1775791362; bh=R3qfDw7crVOy8R1j2TZwYuQoVv5jXQP+cKnUXI5OagA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=G+yp2+waAu91yxXfiqb8dbQfzSXCQ1iHAvULnso7HPiYfR827OieVKrhS5V8+wMqa q1uW/KbgMfpSlCI44/PT4LXYYbfuLIob2IuOvEmmbUJ3kc2wPSsuZiSlD7bfEPfKmU dGKDbHoGuZZS/wmvK934atJ8TP8nhwh7yAPgkalg= Message-ID: Date: Fri, 10 Apr 2026 08:52:33 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC V1 14/16] arm64/mm: Enable fixmap with 5 level page table To: "David Hildenbrand (Arm)" , linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260224051153.3150613-1-anshuman.khandual@arm.com> <20260224051153.3150613-15-anshuman.khandual@arm.com> <4382c90a-bc92-470e-9aa7-4666753479ca@kernel.org> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <4382c90a-bc92-470e-9aa7-4666753479ca@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260409_202246_699049_E210A547 X-CRM114-Status: UNSURE ( 8.02 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 08/04/26 5:59 PM, David Hildenbrand (Arm) wrote: > On 2/24/26 06:11, Anshuman Khandual wrote: >> Enable fixmap with 5 level page table when required. This creates table >> entries at the PGD level. Add a fallback stub for pgd_page_paddr() when >> (PGTBALE_LEVELS <= 4) which helps in intercepting any unintended usage. > > Can you add the "why" ? Following reworded commit message should work ? ------------------------------------------------------------------ arm64/mm: Enable fixmap with 5 level page table FEAT_D128 halves PTRS_PER_PXX thus shrinking the VA range coverage for each page table level. Hence in order to preserve all existing VA range configurations, some geometry now need to become 5-level. Since fixmap is used to build and manipulate page tables early on during boot the mapping must also gain that additional level which was not required earlier. Enable fixmap with 5 level page table when required. This creates table entries at the PGD level. Add a fallback stub for pgd_page_paddr() when (PGTBALE_LEVELS <= 4) which helps in intercepting any unintended usage. -------------------------------------------------------------------