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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 0BACFC4724C for ; Fri, 1 May 2020 10:37:29 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C45FD21973 for ; Fri, 1 May 2020 10:37:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="pmQifVf2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C45FD21973 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=aSh8MQ4Mi4IsJJDTve91ee7fGi6Eixa3rtI7DrdJ4TI=; b=pmQifVf2gYv8H8 6wTDMyukrbS7DsObMkZyeE66ppFm4YpUjQiLBoNEl0F2IIoq5yFyS40hd40mVca2SpFtZjOt9TkT9 Z1MfqEvK0DNEpw6GD4t8U6ANwB/K7JUJgdL5VdacBe7916yWjTbMnd2dIPsGOIL8M3l2uQBib0USM Gr1ug7PtIVy/bFKBbORN70Hd7ZM2OJc++0nUruigC5AvtMZZCsEy8WK961+cXIc22Qmr3EQHFyjdc Yd+W3mFH2wTm+Cmz0dJsJ1phXvqietqNMsC/bluIq/hvTAi7Q/zoqdccL5v1ubxPi9iOFgejS0ZeG u0PZ2yedCJVKml6r/WSQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jUT2u-0004zI-8S; Fri, 01 May 2020 10:37:28 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jUT2s-0004xo-5F for linux-arm-kernel@lists.infradead.org; Fri, 01 May 2020 10:37:27 +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 7BA4F30E; Fri, 1 May 2020 03:37:22 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.7.8]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8266F3F73D; Fri, 1 May 2020 03:37:20 -0700 (PDT) Date: Fri, 1 May 2020 11:37:12 +0100 From: Mark Rutland To: Greg KH Subject: Re: [PATCH] usb: usbfs: correct kernel->user page attribute mismatch Message-ID: <20200501103712.GA51954@C02TD0UTHF1T.local> References: <20200430211922.929165-1-jeremy.linton@arm.com> <20200501070500.GA887524@kroah.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200501070500.GA887524@kroah.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200501_033726_239780_93307D92 X-CRM114-Status: GOOD ( 11.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: git@thegavinli.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, jarkko.sakkinen@linux.intel.com, stern@rowland.harvard.edu, Jeremy Linton , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, May 01, 2020 at 09:05:00AM +0200, Greg KH wrote: > On Thu, Apr 30, 2020 at 04:19:22PM -0500, Jeremy Linton wrote: > > On arm64, and possibly other architectures, requesting > > IO coherent memory may return Normal-NC if the underlying > > hardware isn't coherent. If these pages are then > > remapped into userspace as Normal, that defeats the > > purpose of getting Normal-NC, as well as resulting in > > mappings with differing cache attributes. > > What is "Normal-NC"? Arm terminology for "Normal Non-Cacheable"; it might be better to say something like: On some architectures (e.g. arm64) an IO coherent mapping may use non-cachable attributes if the relevant device is cache coherent. If userspace mappings are cacheable, these may not be coherent with non-cacheable mappings. On arm64 this is the case for Normal-NC and Normal (cacheable) mappings. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel