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=-3.8 required=3.0 tests=BAYES_00, 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 C4C31C433E0 for ; Mon, 15 Mar 2021 07:54:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 911B364E38 for ; Mon, 15 Mar 2021 07:54:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230053AbhCOHxp convert rfc822-to-8bit (ORCPT ); Mon, 15 Mar 2021 03:53:45 -0400 Received: from mout.kundenserver.de ([212.227.126.131]:37923 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230490AbhCOHxN (ORCPT ); Mon, 15 Mar 2021 03:53:13 -0400 Received: from mail-oi1-f174.google.com ([209.85.167.174]) by mrelayeu.kundenserver.de (mreue012 [213.165.67.97]) with ESMTPSA (Nemesis) id 1Mvbr4-1lbro93JZO-00siaq; Mon, 15 Mar 2021 08:53:12 +0100 Received: by mail-oi1-f174.google.com with SMTP id w125so5050159oib.13; Mon, 15 Mar 2021 00:53:11 -0700 (PDT) X-Gm-Message-State: AOAM530/2VFTefL83eMeQLAF/SnE550b1pFCIsUwSt5YmGobx27vjkUX CIcmi4dYjOgFkYr4soN4pxaL95MqwN8Y1LtIRS4= X-Google-Smtp-Source: ABdhPJxqDGNRsuLazrikYSqY8ylkAVcvSJoIRj7d/B6mgsATUAgDvUWymXPVOUo2C8fqtGFewM/hJKdAajbaWjVXu4k= X-Received: by 2002:a05:6808:313:: with SMTP id i19mr8744619oie.67.1615794790530; Mon, 15 Mar 2021 00:53:10 -0700 (PDT) MIME-Version: 1.0 References: <8070f03d-8233-636b-5ea9-395e723f7a2c@intel.com> <503b88c9-1e82-a3a3-0536-d710ddc834a5@redhat.com> In-Reply-To: From: Arnd Bergmann Date: Mon, 15 Mar 2021 08:52:53 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v7] i2c: virtio: add a virtio i2c frontend driver To: Jie Deng Cc: Jason Wang , Linux I2C , virtualization@lists.linux-foundation.org, "linux-kernel@vger.kernel.org" , "Michael S. Tsirkin" , Wolfram Sang , Wolfram Sang , Andy Shevchenko , conghui.chen@intel.com, kblaiech@mellanox.com, jarkko.nikula@linux.intel.com, Sergey Semin , Mike Rapoport , loic.poulain@linaro.org, Tali Perry , =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= , Bjorn Andersson , yu1.wang@intel.com, shuo.a.liu@intel.com, Viresh Kumar , Stefan Hajnoczi , Paolo Bonzini Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Provags-ID: V03:K1:BIrgCmy1rfldfXWXyj/vcSm89E881KI0NZP+gwg1MTy0coAWtpG 1C8788xpaJIQgzNiUU5ZAj6dfbGu40kLTyL445zFnRxWzkiBy+2zr5Rz9G5Jb9IjPagLBeC AuG7WlXMpUfKUUorcYJyW92SIj3NsWZupCGlK3H9Qc570ytncUvAmESBk0O72hbCtrjyuor UlPDZ7/MJEM7GPUUPRICA== X-UI-Out-Filterresults: notjunk:1;V03:K0:Mby2l7qk0+I=:XRr1Iqx/nCwYXRbp73WoPo i5piTO0vEvlWJhm0qRngxbr0Of3CgnNUzdtHkBAIjcYEq0Au6BZ17uroMtHIy+5Ac+yvJrTyk bC16ClVAkkMNlDBDLHy5SVFCD85JcSHsSOWglYj0VvAp4DXdJh09D4Hi3IAKhBmI/q7tM31dB ZrVav8msmWKJ3VPa18qSn9KzNEKkF3crOnGjjGQaQ60D/99LSiqO+t1aHfCpsh07CdjdpZV5N 2eZxKAj+cff1Nwk2ORgf6GYmnMJgC3ssBeEwdlOOZL0vqyaxs6IBnq4/sG5qkJKu7JLqUYJk9 ueLQL0TDHdJFV2kUuH8cO70aYHeVy6Ay74OdNW/6VAEaHx/bH+/3cqbp3JGVii9Cf5/C8zUGp 0bob8mV9ED1nBDqEvv9UBsqiqOAFw1nDXlRgV1I38imrug6GDjEKBKMtqMG/t Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On Mon, Mar 15, 2021 at 6:54 AM Jie Deng wrote: > On 2021/3/15 11:13, Jason Wang wrote: > > On 2021/3/15 9:14 上午, Jie Deng wrote: > >> On 2021/3/12 16:58, Arnd Bergmann wrote: > > > Then do you think it is necessary to mark the virtio bufs with > ____cacheline_aligned ? I think so, yes. > I haven't seen any virtio interface being marked yet. If this is a > problem, I believe it should be common for all virtio devices, right ? Yes, but it's not a problem if the buffers are allocated separately because kmalloc provinces a cachelinen aligned buffer on architectures that need it. It's only a problem here because there is a single allocation for three objects that have different ownership states during the DMA (device owned to-device, cpu-owned, device owned to-cpu). Arnd