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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C0D83C07E95 for ; Wed, 7 Jul 2021 15:36:55 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 21E2061CBE for ; Wed, 7 Jul 2021 15:36:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 21E2061CBE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46266 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m19bZ-0002sn-Ul for qemu-devel@archiver.kernel.org; Wed, 07 Jul 2021 11:36:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43562) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m19ah-0002Cq-FK for qemu-devel@nongnu.org; Wed, 07 Jul 2021 11:35:59 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:54156) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m19ad-0001yB-Vx for qemu-devel@nongnu.org; Wed, 07 Jul 2021 11:35:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625672154; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=2W9E/ofk/FWncGxSr8OtZgA9nwUDBIltcl7pgkVB28k=; b=ZDgipvM61k/G8rOYFLmXTGfBbdx475dPwoi0wKrDjDbYvMe3XK8bAmBlUsFt4KXtd8nueD q6063VDB1vIgzLG9Cz2IXLNKhfZlSqrpEpQoExB+d3rFoWivOGGLyWsSPdpdCh5CAfOXrY G7vH7kHNJTzYNyYbIjTwrU3HERUb1Yc= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-165-NSziPc9xOmO-w7pHhUQuQA-1; Wed, 07 Jul 2021 11:35:51 -0400 X-MC-Unique: NSziPc9xOmO-w7pHhUQuQA-1 Received: by mail-qv1-f70.google.com with SMTP id f16-20020ad442d00000b029028c5121bf35so1857447qvr.10 for ; Wed, 07 Jul 2021 08:35:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=2W9E/ofk/FWncGxSr8OtZgA9nwUDBIltcl7pgkVB28k=; b=tbHSqLU7e2foo1+I0IgF4pgNoGDdzTfb12X71hJVBnZxQM7clSvqT7Vd+vc8UqygNi h20TY75ryGJhOYT8Ilg+CgFyR9NVzTWijcY7V7DgqRf3z1ERa2Jwp7iWtO0sM4njpwSK m/hbpymTDtGjpYOF3WKZM5Gcs0MrZAi7RHdNRVZStXqSL+/YwCPflgh4l8p9npxk2pRg n0bUufCagnku5GwLAywgTjF9nqLE75bljkyk8y7I33AfuD0wuEVzVl659Po8WLdJ4QKT mkVoGmp+NoCiGKz9e6KF41P3eIlmKUKqg8hO6GZvG8bnmcfw+x/YW1U/HHYBqRbhU0Gk iJBg== X-Gm-Message-State: AOAM5332prl7fUeFiSZnB4De0Mmi9X8j86+55/0qgJvJIo0J+fVuUSxC SPw6HsVk+Q3M9ElZxWK9Y0bwr1ueguZwRisY6IlGPGnAIk2IjCCi9KpGsN03OD5GvcFyDc57D83 NJFuOT3CIbIwFKV8= X-Received: by 2002:ac8:1008:: with SMTP id z8mr22496763qti.232.1625672151375; Wed, 07 Jul 2021 08:35:51 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwUR273VFbIN6CSNXuD7J//inW8KNnn9uPMxlNgAcXn1we9ZKe6lUkM7LufTHmd15HRK4dYpw== X-Received: by 2002:ac8:1008:: with SMTP id z8mr22496743qti.232.1625672151140; Wed, 07 Jul 2021 08:35:51 -0700 (PDT) Received: from t490s (bras-base-toroon474qw-grc-65-184-144-111-238.dsl.bell.ca. [184.144.111.238]) by smtp.gmail.com with ESMTPSA id f8sm3986210qtk.49.2021.07.07.08.35.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jul 2021 08:35:50 -0700 (PDT) Date: Wed, 7 Jul 2021 11:35:49 -0400 From: Peter Xu To: Eric Auger Subject: Re: [PATCH] docs: Add '-device intel-iommu' entry Message-ID: References: <20210611185500.343525-1-peterx@redhat.com> <6355528a-5d67-f178-90f9-53103d7540f1@redhat.com> MIME-Version: 1.0 In-Reply-To: <6355528a-5d67-f178-90f9-53103d7540f1@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.439, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: "Michael S . Tsirkin" , Jason Wang , qemu-devel@nongnu.org, Alex Williamson , Jing Zhao , Lei Yang , Chao Yang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jul 07, 2021 at 11:29:47AM +0200, Eric Auger wrote: > Hi Peter, Hi, Eric, > > On 6/11/21 8:55 PM, Peter Xu wrote: > > The parameters of intel-iommu device are non-trivial to understand. Add an > > entry for it so that people can reference to it when using. > > > > There're actually a few more options there, but I hide them explicitly because > > they shouldn't be used by normal QEMU users. > > > > Cc: Chao Yang > > Cc: Lei Yang > > Cc: Jing Zhao > > Cc: Jason Wang > > Cc: Michael S. Tsirkin > > Cc: Alex Williamson > > Signed-off-by: Peter Xu > > --- > > qemu-options.hx | 32 ++++++++++++++++++++++++++++++++ > > 1 file changed, 32 insertions(+) > > > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 14258784b3a..4bb04243907 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -926,6 +926,38 @@ SRST > > > > ``-device pci-ipmi-bt,bmc=id`` > > Like the KCS interface, but defines a BT interface on the PCI bus. > > + > > +``-device intel-iommu[,option=...]`` > > + This is only supported by ``-machine q35``, which will enable Intel VT-d > > + emulation within the guest. It supports below options: > > + > > + ``intremap=on|off`` (default: auto) > > + This enables interrupt remapping feature in the guest. It's required > > + to enable complete x2apic. Currently it only supports kvm > > + kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is not > > + yet supported. > maybe explain how the default is chosen (based on kernel-irqhcip mode?) Will do. > > + > > + ``caching-mode=on|off`` (default: off) > > + This enables caching mode for the VT-d emulated device. When > > + caching-mode is enabled, each guest DMA buffer mapping will generate an > > + IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in > > + a synchronous way. It is required for ``-device vfio-pci`` to work > > + with the VT-d device, because host assigned devices requires to setup > > + the DMA mapping on the host before guest DMA starts. > > + > > + ``device-iotlb=on|off`` (default: off) > > + This enables device-iotlb capability for the emulated VT-d device. So > > + far virtio/vhost should be the only real user for this parameter, > I thought if was needed for vhost. What is the usage for virtio? I used "virtio/vhost" because vhost is only one type of virtio backend, so normally they should be used in pair. Also, the "ats=on" parameter should be an option to virtio frontend rather than vhost, hence I mentioned both. > > + paired with ats=on configured for the device. > What is not obvious to me is whether there is a kind of diagnosis > whether device-iotlb and caching mode settings are consistent with > vfio/vhost usage. Does qemu exit if there is inconsistency? Caching mode check is done in vtd_machine_done_notify_one(). I think there's no such check for vhost, however iirc vhost should work with/without ats=on; I did't check deeper. > > + > > + ``aw-bits=39|48`` (default: 39) > > + This decides the address width of IOVA address space. The address > > + space has 39 bits width for 3-level IOMMU page tables, and 48 bits for > > + 4-level IOMMU page tables. > > + > > + Please also refer to the wiki page for general scenarios of VT-d > > + emulation in QEMU: https://wiki.qemu.org/Features/VT-d. > > + > > ERST > > > > DEF("name", HAS_ARG, QEMU_OPTION_name, > > > Besides, it is quite useful. Thanks for taking a look! -- Peter Xu