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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 9531DC10F14 for ; Tue, 8 Oct 2019 15:32:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 63133217D7 for ; Tue, 8 Oct 2019 15:32:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63133217D7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D5A948E0005; Tue, 8 Oct 2019 11:32:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D0BE58E0003; Tue, 8 Oct 2019 11:32:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C20938E0005; Tue, 8 Oct 2019 11:32:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0035.hostedemail.com [216.40.44.35]) by kanga.kvack.org (Postfix) with ESMTP id 9A8008E0003 for ; Tue, 8 Oct 2019 11:32:08 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 303CA181AC9B6 for ; Tue, 8 Oct 2019 15:32:08 +0000 (UTC) X-FDA: 76021008336.01.eggs80_699cc61dfff0a X-HE-Tag: eggs80_699cc61dfff0a X-Filterd-Recvd-Size: 5050 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Oct 2019 15:32:05 +0000 (UTC) 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 8BC121570; Tue, 8 Oct 2019 08:32:04 -0700 (PDT) Received: from dawn-kernel.cambridge.arm.com (unknown [10.1.197.116]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A0E883F68E; Tue, 8 Oct 2019 08:32:02 -0700 (PDT) Subject: Re: [PATCH v10 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() To: "Justin He (Arm Technology China)" , Marc Zyngier , Will Deacon Cc: Mark Rutland , "Kaly Xin (Arm Technology China)" , Catalin Marinas , "linux-kernel@vger.kernel.org" , Matthew Wilcox , "linux-mm@kvack.org" , James Morse , "linux-arm-kernel@lists.infradead.org" , Punit Agrawal , "hejianet@gmail.com" , Thomas Gleixner , Andrew Morton , "Kirill A. Shutemov" References: <20190930015740.84362-1-justin.he@arm.com> <20190930015740.84362-2-justin.he@arm.com> <20191001125446.gknoofnm7az4wqf5@willie-the-truck> <20191001141848.762296bd@why> From: Suzuki K Poulose Message-ID: Date: Tue, 8 Oct 2019 16:32:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=gbk; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 08/10/2019 02:12, Justin He (Arm Technology China) wrote: > Hi Will and Marc > Sorry for the late response, just came back from a vacation. >=20 >> -----Original Message----- >> From: Marc Zyngier >> Sent: 2019=C4=EA10=D4=C21=C8=D5 21:19 >> To: Will Deacon >> Cc: Justin He (Arm Technology China) ; Catalin >> Marinas ; Mark Rutland >> ; James Morse ; >> Matthew Wilcox ; Kirill A. Shutemov >> ; linux-arm-kernel@lists.infradead.or= g; >> linux-kernel@vger.kernel.org; linux-mm@kvack.org; Punit Agrawal >> ; Thomas Gleixner ; >> Andrew Morton ; hejianet@gmail.com; Kaly >> Xin (Arm Technology China) >> Subject: Re: [PATCH v10 1/3] arm64: cpufeature: introduce helper >> cpu_has_hw_af() >> >> On Tue, 1 Oct 2019 13:54:47 +0100 >> Will Deacon wrote: >> >>> On Mon, Sep 30, 2019 at 09:57:38AM +0800, Jia He wrote: >>>> We unconditionally set the HW_AFDBM capability and only enable it on >>>> CPUs which really have the feature. But sometimes we need to know >>>> whether this cpu has the capability of HW AF. So decouple AF from >>>> DBM by new helper cpu_has_hw_af(). >>>> >>>> Signed-off-by: Jia He >>>> Suggested-by: Suzuki Poulose >>>> Reviewed-by: Catalin Marinas >>>> --- >>>> arch/arm64/include/asm/cpufeature.h | 10 ++++++++++ >>>> 1 file changed, 10 insertions(+) >>>> >>>> diff --git a/arch/arm64/include/asm/cpufeature.h >> b/arch/arm64/include/asm/cpufeature.h >>>> index 9cde5d2e768f..949bc7c85030 100644 >>>> --- a/arch/arm64/include/asm/cpufeature.h >>>> +++ b/arch/arm64/include/asm/cpufeature.h >>>> @@ -659,6 +659,16 @@ static inline u32 >> id_aa64mmfr0_parange_to_phys_shift(int parange) >>>> default: return CONFIG_ARM64_PA_BITS; >>>> } >>>> } >>>> + >>>> +/* Check whether hardware update of the Access flag is supported */ >>>> +static inline bool cpu_has_hw_af(void) >>>> +{ >>>> + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) >>>> + return read_cpuid(ID_AA64MMFR1_EL1) & 0xf; >>> >>> 0xf? I think we should have a mask in sysreg.h for this constant. >> >> We don't have the mask, but we certainly have the shift. >> >> GENMASK(ID_AA64MMFR1_HADBS_SHIFT + 3, >> ID_AA64MMFR1_HADBS_SHIFT) is a bit >> of a mouthful though. Ideally, we'd have a helper for that. >> > Ok, I will implement the helper if there isn't so far. > And then replace the 0xf with it. Or could we simpl reuse existing cpuid_feature_extract_unsigned_field() ? u64 mmfr1 =3D read_cpuid(ID_AA64MMFR1_EL1); return cpuid_feature_extract_unsigned_field(mmfr1, ID_AA64MMFR1_HADBS_SHI= FT) ? Cheers Suzuki