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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 005EDC07E9A for ; Wed, 14 Jul 2021 08:21:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D90DA613B2 for ; Wed, 14 Jul 2021 08:21:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238473AbhGNIX4 (ORCPT ); Wed, 14 Jul 2021 04:23:56 -0400 Received: from foss.arm.com ([217.140.110.172]:59498 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229940AbhGNIXz (ORCPT ); Wed, 14 Jul 2021 04:23:55 -0400 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 E06BA31B; Wed, 14 Jul 2021 01:21:03 -0700 (PDT) Received: from [10.57.33.248] (unknown [10.57.33.248]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2D0243F9AB; Wed, 14 Jul 2021 01:21:02 -0700 (PDT) Subject: Re: [RFC 07/10] arm64/mm: Detect and enable FEAT_LPA2 To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: akpm@linux-foundation.org, mark.rutland@arm.com, will@kernel.org, catalin.marinas@arm.com, maz@kernel.org, james.morse@arm.com, steven.price@arm.com References: <1626229291-6569-1-git-send-email-anshuman.khandual@arm.com> <1626229291-6569-8-git-send-email-anshuman.khandual@arm.com> From: Suzuki K Poulose Message-ID: <18c42dd0-b6db-d118-dad0-cac0bf6ab2ce@arm.com> Date: Wed, 14 Jul 2021 09:21:00 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <1626229291-6569-8-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/07/2021 03:21, Anshuman Khandual wrote: > Detect FEAT_LPA2 implementation early enough during boot when requested via > CONFIG_ARM64_PA_BITS_52_LPA2 and remember in a variable arm64_lpa2_enabled. > This variable could then be used to turn on TCR_EL1.TCR_DS effecting the 52 > bits PA range or fall back to default 48 bits PA range if FEAT_LPA2 feature > was requested but found not to be implemented. > > Signed-off-by: Anshuman Khandual > --- > arch/arm64/include/asm/memory.h | 1 + > arch/arm64/kernel/head.S | 15 +++++++++++++++ > arch/arm64/mm/mmu.c | 3 +++ > arch/arm64/mm/proc.S | 9 +++++++++ > 4 files changed, 28 insertions(+) > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index 824a365..d0ca002 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -178,6 +178,7 @@ > #include > > extern u64 vabits_actual; > +extern u64 arm64_lpa2_enabled; > > extern s64 memstart_addr; > /* PHYS_OFFSET - the physical address of the start of memory. */ > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index 6444147..9cf79ea 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -94,6 +94,21 @@ SYM_CODE_START(primary_entry) > adrp x23, __PHYS_OFFSET > and x23, x23, MIN_KIMG_ALIGN - 1 // KASLR offset, defaults to 0 > bl set_cpu_boot_mode_flag > + > +#ifdef CONFIG_ARM64_PA_BITS_52_LPA2 > + mrs x10, ID_AA64MMFR0_EL1 > + ubfx x10, x10, #ID_AA64MMFR0_TGRAN_SHIFT, 4 > + cmp x10, #ID_AA64MMFR0_TGRAN_LPA2 > + b.ne 1f For the sake of forward compatibility, this should be "b.lt" Suzuki