From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by 2002:a19:5205:0:0:0:0:0 with SMTP id m5csp311668lfb; Wed, 8 Sep 2021 03:35:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxwaJ/3r/4AC1dlJX+OwoJ1PtiXKTetlu2UGRoGdVQGHpcXp6h5wp3lkY9h8Mb6QJyC5Fxc X-Received: by 2002:a92:ca85:: with SMTP id t5mr2315201ilo.109.1631097349337; Wed, 08 Sep 2021 03:35:49 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1631097349; cv=none; d=google.com; s=arc-20160816; b=T9vbMEKc5cG36Z1x6XwkQ0a+mtLCEUe1wqdtbcpNFUdO1VCFQI0OhvUP3Mbop2Q68X AxVf2ops8odAekt1qBy2F8z3pVZtDqoLXtNqJyALpecC7oPl6Mk5mTtVgX3XzqNZeUTu X9ViwQpow6rbtET3wM2XFToUghupt4V0Alwy4DIQlQj4sliycqZzkdJ3aYNdP/leojC6 qhX+O70PjAyRo7t/QFQoYSa+CdMhpiAzaC6hnbbt4B+t7TWjrbLSiEJOlcB3SxjOhAJw KCQ0yiTpelS36KLQks3fS239dqrbZEFHMEU/lkGItQivP4bQ9hamTFJ5aWPomZEPD50Y 8NDw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:cc:list-subscribe:list-help:list-post:list-archive :list-unsubscribe:list-id:precedence:in-reply-to :content-transfer-encoding:content-disposition:mime-version :references:message-id:subject:to:from:date:dkim-signature; bh=hglgwo8uVM8lqoCwpiy6NiQvi4JgQ4hmiTtQcuXFvHk=; b=j5yGNos8+zXueqaGGbvVbQtXOMgL68ktALuE59NvJbBD4f55J+jX0PPV148vrsmoE8 4GEDDEkHbjyCY6dXCOLzXPGmGP3qjAN2i/P9FU3yZKk6Yp9wqMDru3iERG4MeobKZKF/ AkKm/UmRQQgOe9eb+qNse/GRAjj4JSyRMLB9I8KkZk3n43Qozz/K4R9ru/3/x5Y0Z4yN 8QX0PV2ZkQN96tfRkaxd01Nxc9vVGY3MdHGXIoapgkPyZcGmf7P4meUz6PFFTXqx5RC/ ZfCpdi6WXDITKsj7PnqXdvi3JCTF9JDbOQvJB0b4h/z+89FedgjXrEj3U1uPf8GmLWzo wigQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@linaro.org header.s=google header.b=oo8pq7rh; spf=pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from lists.gnu.org (lists.gnu.org. [209.51.188.17]) by mx.google.com with ESMTPS id k7si1723146ior.112.2021.09.08.03.35.49 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 08 Sep 2021 03:35:49 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=fail header.i=@linaro.org header.s=google header.b=oo8pq7rh; spf=pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: from localhost ([::1]:42840 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mNuvk-0002Oa-LN for alex.bennee@linaro.org; Wed, 08 Sep 2021 06:35:48 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40646) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNuYx-0006GS-4p for qemu-devel@nongnu.org; Wed, 08 Sep 2021 06:12:15 -0400 Received: from mail-wr1-x42a.google.com ([2a00:1450:4864:20::42a]:34525) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mNuYu-0000T4-I9 for qemu-devel@nongnu.org; Wed, 08 Sep 2021 06:12:14 -0400 Received: by mail-wr1-x42a.google.com with SMTP id m9so2465136wrb.1 for ; Wed, 08 Sep 2021 03:12:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=hglgwo8uVM8lqoCwpiy6NiQvi4JgQ4hmiTtQcuXFvHk=; b=oo8pq7rh9zryaxLIo3RZpb65QOG1R8APYdxdei104LR01ZsCCLK2ypVK6lTcXEDk65 gjv71Uf8Mwgef0EOkA0u/VMcL9pqhIQ60Zt2iBKtnYOku9I3i619jVsiyvT1FkM8NmHm OMWafMCJ5pfCYuDn4rIsnzlL8bXsAaylvSxBL5hFcZQEcLvR0dlzmInYw8fXUukESdLM +acfVOzclTTUh2GI/bzc3r2OAQhI5dyhxSTPJcUpk92U12EVjA9Dqwimd+8L8Su0Kphh gQxQqQzii7buka5qhNPkSxm5KU91YFdvQfOL9XjnCFSFVfihgHDDLqyhyHfNugPpNlQL 9W1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=hglgwo8uVM8lqoCwpiy6NiQvi4JgQ4hmiTtQcuXFvHk=; b=LOQU3NnEtFCsI8/Awzm/evwkSd8NCUbzAkNm96Rfz+QyzU93m6ZHDvtg0jILB/8hFG tLCgZeOJl+o9/Phcf0JXkCEJZw2MRPjDYB530E/bBhQQHx/iSwV0E7YwYrtqOuQo15p3 YJ8QumooVIpT+8V4giHqPyPROh6LjkTQ91rDBOmjF5Wo4Riyg5e6umHcXlZYHY+GytYW SHTxDpU30Jlz1sES/5vo8rzYiCi8YIxAXk6vZSoUmSXL0YcIK3tbqaEochWX+qzIjHK/ UzHQwakQO6JGiGyEokFzMC8mn1YgQxlGrElHqlMCjApiRsHxDB0m6Rg0dqe1oGwSoq2m BHkw== X-Gm-Message-State: AOAM533JkN3KdMCNtTyp6hmmyD0TMfISC2GDE42hTLRcUKHJrVIs2LFt jFwZHZWN2QcnI3SZKY4ioXpgYQ== X-Received: by 2002:a5d:4f88:: with SMTP id d8mr2678252wru.358.1631095930992; Wed, 08 Sep 2021 03:12:10 -0700 (PDT) Received: from larix (cpc92880-cmbg19-2-0-cust679.5-4.cable.virginm.net. [82.27.106.168]) by smtp.gmail.com with ESMTPSA id f17sm1921439wrt.63.2021.09.08.03.12.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Sep 2021 03:12:10 -0700 (PDT) Date: Wed, 8 Sep 2021 11:14:20 +0100 From: Jean-Philippe Brucker To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Subject: Re: [PATCH v2 8/8] docs: Add '-device virtio-iommu' entry Message-ID: References: <20210903143208.2434284-1-jean-philippe@linaro.org> <20210903143208.2434284-9-jean-philippe@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=2a00:1450:4864:20::42a; envelope-from=jean-philippe@linaro.org; helo=mail-wr1-x42a.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, ehabkost@redhat.com, mst@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org, eric.auger@redhat.com, shannon.zhaosl@gmail.com, qemu-arm@nongnu.org, imammedo@redhat.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-devel" X-TUID: PLVYX1sXvpwR On Mon, Sep 06, 2021 at 03:45:28PM +0100, Daniel P. Berrangé wrote: > On Fri, Sep 03, 2021 at 04:32:09PM +0200, Jean-Philippe Brucker wrote: > > Document the virtio-iommu device for qemu-system-x86_64. In particular > > note the lack of interrupt remapping, which may be an important > > limitation on x86. > > > > Suggested-by: Eric Auger > > Signed-off-by: Jean-Philippe Brucker > > --- > > qemu-options.hx | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 83aa59a920..9a1906a748 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -976,6 +976,9 @@ SRST > > Please also refer to the wiki page for general scenarios of VT-d > > emulation in QEMU: https://wiki.qemu.org/Features/VT-d. > > > > +``-device virtio-iommu`` > > + Enable a paravirtual IOMMU, that manages DMA isolation and remapping > > + for all PCI devices, but does not support interrupt remapping. > > It would be desirable to document why this is better/worse/equiv to > the intel-iommu device documented just before, so that people have a > better idea of which they should be trying to use. > > I'm going to assume intel-iommu is more likely to "just work" out of > the box since it models real hardware that OS are likely to already > support ? Is that right though ? That's right, and there isn't much point in using virtio-iommu on q35 at the moment, we're still laying the foundation. It only implements caching mode for now so it complements the vSMMU on arm which doesn't have that, but on x86 QEMU it doesn't add anything useful. There are extensions to get better performance for different type of endpoint, and other features, but those are all work in progress. I thinks I'll just drop the documentation patch until the device is more mature and I have something useful to write here. The other IOMMUs are not described either at the moment. x86 users will just instantiate the intel-iommu as usual if they need an IOMMU. Thanks, Jean