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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 CF618C4CEC4 for ; Wed, 18 Sep 2019 14:20:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 924642196E for ; Wed, 18 Sep 2019 14:20:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="j0d7BbTA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 924642196E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 17D336B02C1; Wed, 18 Sep 2019 10:20:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 12D456B02C2; Wed, 18 Sep 2019 10:20:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 043106B02C3; Wed, 18 Sep 2019 10:20:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0220.hostedemail.com [216.40.44.220]) by kanga.kvack.org (Postfix) with ESMTP id D7A296B02C1 for ; Wed, 18 Sep 2019 10:20:23 -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 72660181AC9B4 for ; Wed, 18 Sep 2019 14:20:23 +0000 (UTC) X-FDA: 75948251526.01.wood66_3d8ea164d8040 X-HE-Tag: wood66_3d8ea164d8040 X-Filterd-Recvd-Size: 2946 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Sep 2019 14:20:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=DMq3xUbm3Tba1ioJ8DBESEZ5dfTNXfLnh6d+gS2fyMo=; b=j0d7BbTAvNp9ZBwF3w1M7xXOR zlRtmrVxGkJ0yMLkv+nxpymU1ev0nBhurZbTO0LEhYTMLQ2/lK3LvD69O+kB3yJGlHuV+VD/XnNSn eINo+UfM3D0lNxRNCEappYbYW/AmV03vZskWHxHEbfQpIIVBDwYtmfMcOO9EW5UV/wCo/MQV32YHe osVm3YYuYpMCSm8yOpRFUqdAl78gxnnUkfx+9rk0D5155UEAoiwJ9hma3GR33sH7EsdwxM1xB6rbs DN5MiK9y7+uzFA9FAL5FyK32bdHPvtFBt22hUfyPe3jIGc9/PDnxjW3abmEhptFO+/Rjq9pL2fwk2 a3I2ZKVlQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.2 #3 (Red Hat Linux)) id 1iAaob-0006gt-J4; Wed, 18 Sep 2019 14:20:17 +0000 Date: Wed, 18 Sep 2019 07:20:17 -0700 From: Matthew Wilcox To: Jia He Cc: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose , Punit Agrawal , Anshuman Khandual , Jun Yao , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?iso-8859-1?B?Suly9G1l?= Glisse , Ralph Campbell , hejianet@gmail.com, Kaly Xin Subject: Re: [PATCH v4 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Message-ID: <20190918142017.GC9880@bombadil.infradead.org> References: <20190918131914.38081-1-justin.he@arm.com> <20190918131914.38081-2-justin.he@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190918131914.38081-2-justin.he@arm.com> User-Agent: Mutt/1.12.1 (2019-06-15) 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 Wed, Sep 18, 2019 at 09:19:12PM +0800, Jia He wrote: > +/* Decouple AF from AFDBM. */ > +bool cpu_has_hw_af(void) > +{ > + return (read_cpuid(ID_AA64MMFR1_EL1) & 0xf); > +} > + Do you really want to call read_cpuid() every time? I would have thought you'd want to use the static branch mechanism to do the right thing at boot time. See Documentation/static-keys.txt.