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=-5.3 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,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 1B84FC433E2 for ; Tue, 21 Jul 2020 18:16:55 +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 DBE3F2073A for ; Tue, 21 Jul 2020 18:16:54 +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="FHoj2GBF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DBE3F2073A 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 1jxwoZ-0007qV-Ap; Tue, 21 Jul 2020 18:16:31 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jxwoX-0007qQ-VR for xen-devel@lists.xenproject.org; Tue, 21 Jul 2020 18:16:30 +0000 X-Inumbo-ID: 4bafde9b-cb7e-11ea-859b-bc764e2007e4 Received: from mail-lj1-x234.google.com (unknown [2a00:1450:4864:20::234]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 4bafde9b-cb7e-11ea-859b-bc764e2007e4; Tue, 21 Jul 2020 18:16:29 +0000 (UTC) Received: by mail-lj1-x234.google.com with SMTP id h22so25091909lji.9 for ; Tue, 21 Jul 2020 11:16:29 -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=ghgcnfJ7kfPCIJeWCLlLLzJzBObkZ6CFvEmgHiR5fpU=; b=FHoj2GBFieqignXTbxCB+0wkPeEL+vka6roLWyC0UrwI8So9NsftB0Se9hWh45v88a nOKYri7Zbv9iBdKl2tXG6Upyl411svPay1tgDHPw7ZpcQYerdF13++lqVgn+0ccqrX4h 6aScQGJeeozOJsX7eU1XgfTQ+SLYHWwLYGYxcB8VIfTj4wgxwf+h+4/Yb/oa95lrm8ih vYqcTyLk/sLtfmJiSeguhame9/gwDGNhP0PpT89D53pacjbWhQAdKxSf9MacNnlX0X7K q3C7z/6c7050lwKeVNXvOIAhIiAI6P+ERmNsbQTMOr7P7xbTsTRrwyvs218ptHYpT41i ucGQ== 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=ghgcnfJ7kfPCIJeWCLlLLzJzBObkZ6CFvEmgHiR5fpU=; b=IRcprdl5a0yfWOD8oDqOpd6J4JjMmXQDj+jn3aifkmBjAwknovmc/AdqEC/lbuy2Z8 hY3jraCFFcr38fu+BkGO7fhr0wPja5kPWkqUBISqUw2hwDmje9eRRQsQguXMg1TWuGN0 R7smI9kIurlJnLD1BJSHNRXiiXReN5QSr6OJKjG3+usF+tb2DPuiZViUkphnCMTgjAbj pljpPJJdovxIiYOkMoI+pXo3KJZdd2AbcxsbrI21TOfkNw8ncgFpUoijzjDGJ4Y6uM1+ ptuj5czzj/e8l/554kQTKldeEpxbQIaQ6Ki61Q3vI93qN+9suMNIeYcFOJxS67T7R1GG 1Xqg== X-Gm-Message-State: AOAM533d/dXNr0HI+ooIVewXgpCtd81wJFdLmsu9fUw4PkNk/8Gq9mC2 DjnXblSYPeDpjjOZRH639eU= X-Google-Smtp-Source: ABdhPJz36GWHMGv84VN14p7ikCiTsMkejxPKOC8xAHrfxJX8r9Dbh3AIonidQGZz3pK6x6YM78OICA== X-Received: by 2002:a2e:50b:: with SMTP id 11mr13921574ljf.458.1595355387971; Tue, 21 Jul 2020 11:16:27 -0700 (PDT) Received: from [192.168.1.2] ([212.22.223.21]) by smtp.gmail.com with ESMTPSA id r14sm2074466lfe.29.2020.07.21.11.16.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Jul 2020 11:16:27 -0700 (PDT) Subject: Re: Virtio in Xen on Arm (based on IOREQ concept) To: Julien Grall References: <20200717150039.GV7191@Air-de-Roger> <8f4e0c0d-b3d4-9dd3-ce20-639539321968@gmail.com> <3dcab37d-0d60-f1cc-1d59-b5497f0fa95f@xen.org> From: Oleksandr Message-ID: Date: Tue, 21 Jul 2020 21:16:21 +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: <3dcab37d-0d60-f1cc-1d59-b5497f0fa95f@xen.org> 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: Stefano Stabellini , Oleksandr Andrushchenko , Bertrand Marquis , xen-devel , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Artem Mygaiev Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 21.07.20 17:27, Julien Grall wrote: > Hi, Hello > > On a similar topic, I am a bit surprised you didn't encounter memory > exhaustion when trying to use virtio. Because on how Linux currently > works (see XSA-300), the backend domain as to have a least as much RAM > as the domain it serves. For instance, you have serve two domains with > 1GB of RAM each, then your backend would need at least 2GB + some for > its own purpose. > > This probably wants to be resolved by allowing foreign mapping to be > "paging" out as you would for memory assigned to a userspace. Didn't notice the last sentence initially. Could you please explain your idea in detail if possible. Does it mean if implemented it would be feasible to map all guest memory regardless of how much memory the guest has? Avoiding map/unmap memory each guest request would allow us to have better performance (of course with taking care of the fact that guest memory layout could be changed)... Actually what I understand looking at kvmtool is the fact it does not map/unmap memory dynamically, just calculate virt addresses according to the gfn provided. -- Regards, Oleksandr Tyshchenko