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=-8.3 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 743BBC433DF for ; Wed, 5 Aug 2020 20:36:02 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 41350206D4 for ; Wed, 5 Aug 2020 20:36:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="E6PIY3OC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41350206D4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k3Q8V-0004Ga-Kx; Wed, 05 Aug 2020 20:35:43 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k3Q8U-0004GV-GG for xen-devel@lists.xenproject.org; Wed, 05 Aug 2020 20:35:42 +0000 X-Inumbo-ID: e03fe94c-19ab-41fd-b05c-461ace6b62c7 Received: from mail-lj1-x242.google.com (unknown [2a00:1450:4864:20::242]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id e03fe94c-19ab-41fd-b05c-461ace6b62c7; Wed, 05 Aug 2020 20:35:41 +0000 (UTC) Received: by mail-lj1-x242.google.com with SMTP id s16so33982682ljc.8 for ; Wed, 05 Aug 2020 13:35:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=1YXgAcf/MkURvy5fQI+D8jfLLLAeCGsmKnn68DUsZ1c=; b=E6PIY3OCuHOcBzxx7Kg6w0BCxIbeSkFhMiVY4qwom/Budu6VBpBCBmrw2p7zD1l9Dg lmnqyiRsz4FvQus93cZ0/S6YTjA/B0Cn+derj+bhH/xutLJbzGU+D71Lynee60ZNFb/Q uX+/P1BXBpYvkCwXCNOKvbmGqTU3sNzmS1bHGHEIuiZ9xEdmMbmf5lH88LbSg8QyMbPB ySlfXwI54JZ78GqyY+yb8YVdvPt4ui+yQeKPsq1El9mgnIJhhQ8F6jAALQghPna8hnUX XORpMsi/LC8ILrK04AsSSJO0EpByOTi/qYksB8BWowXRISYrnUMpc7tlkHnGlT3qH9+o /mwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=1YXgAcf/MkURvy5fQI+D8jfLLLAeCGsmKnn68DUsZ1c=; b=Pr0Tdtm3w9F1LyJ9+Ubn0sGQZJte8NAO9wkFfBZQXUwwavLzG7OtVWmyIoev/uUNM0 jvj8Mysl0fpIRdZJS/3SfFd+Uk4xajrqR4YnLsthdHXvKEof1eCtUCHfjPBXfBFNau6k Ghi4wgwUwmwyLL/np5BUnB41G/qEyXlGh5me2BRARPE5W1hU1bG3wlJAMOEc2tnfeguO lX9h1PmxWniWfjq4qzYMeE+MOBrrkcTBsPPqTE+YFNW8tgmpysTZUUaKyxCWEKxzifSX 5/caupJ69b2qCqGoLUyA3Kb8sxMkIyDtlTduttskwRgfhlCaXx5wKeIbem6+6LfN2zNs fubA== X-Gm-Message-State: AOAM531mvmbqNivSjcovQJnp477tWFbNXOEduL4bagUe0JXcDOi5a4ta 7gOLinsP7WpWkwUjhahcdRE= X-Google-Smtp-Source: ABdhPJwjcNp5wjrYke3++cmCZ8Ebmm7LuoH5Cm7DU8h25kreAbFXeyvXJkM1+1yG0PFE4dufJ2Stdw== X-Received: by 2002:a2e:a49a:: with SMTP id h26mr2093549lji.168.1596659740380; Wed, 05 Aug 2020 13:35:40 -0700 (PDT) Received: from [192.168.1.2] ([212.22.223.21]) by smtp.gmail.com with ESMTPSA id y21sm1329036ljk.129.2020.08.05.13.35.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Aug 2020 13:35:39 -0700 (PDT) Subject: Re: [RFC PATCH V1 11/12] libxl: Insert "dma-coherent" property into virtio-mmio device node To: Stefano Stabellini References: <1596478888-23030-1-git-send-email-olekstysh@gmail.com> <1596478888-23030-12-git-send-email-olekstysh@gmail.com> From: Oleksandr Message-ID: <5ed8d80a-da71-3f54-7e80-9f93bd285e4d@gmail.com> Date: Wed, 5 Aug 2020 23:35:34 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Wei Liu , Ian Jackson , Oleksandr Tyshchenko , Anthony PERARD , xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 05.08.20 02:23, Stefano Stabellini wrote: Hi Stefano > On Mon, 3 Aug 2020, Oleksandr Tyshchenko wrote: >> From: Oleksandr Tyshchenko >> >> Without "dma-coherent" property present in virtio-mmio device node, >> guest assumes it is non-coherent and making non-cacheable accesses >> to the vring when the DMA API is used for vring operations. >> But virtio-mmio device which runs at the host size is making cacheable >> accesses to vring. This all may result in a loss of coherency between >> the guest and host. >> >> With this patch we can avoid modifying guest at all, otherwise we >> need to force VirtIO framework to not use DMA API for vring operations. >> >> Signed-off-by: Oleksandr Tyshchenko > This should also be folded in the first patch for libxl Agree, will do -- Regards, Oleksandr Tyshchenko