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_INVALID, DKIM_SIGNED,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 46470C433E0 for ; Mon, 8 Feb 2021 22:58:09 +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 B119164E7A for ; Mon, 8 Feb 2021 22:58:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B119164E7A 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]:40180 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l9FTr-0002Vl-Lq for qemu-devel@archiver.kernel.org; Mon, 08 Feb 2021 17:58:07 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50654) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l9DC4-0006T8-9C for qemu-devel@nongnu.org; Mon, 08 Feb 2021 15:31:41 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:20517) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l9DBo-0007ek-QR for qemu-devel@nongnu.org; Mon, 08 Feb 2021 15:31:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612816276; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+ooVcD8YXX9U721mrR5tDDi3VicfZg3baMSzX4NQmuI=; b=JLC0G9zSGnDLUmg7VvmYd10NrQZdGzBspnjQRjD9EM4rfCehJWs3+HpVz6Cjxpq/DxVzlf 85yLRdYo/aKwbmRIeLnvjRIN0XeIkmtjYPf88ZngNnpSvBYFW5Dxa7l64/fjsJhdahvF4I MLNQ6jTaNrW3HnLzJcDPbrSHYj8I8z4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-100-dnD1dmr4MnKloemE_wvAcw-1; Mon, 08 Feb 2021 15:31:14 -0500 X-MC-Unique: dnD1dmr4MnKloemE_wvAcw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6435819611A2; Mon, 8 Feb 2021 20:31:13 +0000 (UTC) Received: from [10.36.112.10] (ovpn-112-10.ams2.redhat.com [10.36.112.10]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1DD645D6A8; Mon, 8 Feb 2021 20:30:59 +0000 (UTC) Subject: Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support To: Peter Xu , Jason Wang References: <20210204191228.187550-1-peterx@redhat.com> <2382a93d-41c1-24fd-144f-87ee18171bc9@redhat.com> <213acf9a-d1c0-3a1d-4846-877d90fadc03@redhat.com> <20210205153107.GX6468@xz-x1> <20210208183721.GB68242@xz-x1> From: Auger Eric Message-ID: <77da729f-52d7-8282-9248-74febe61a37b@redhat.com> Date: Mon, 8 Feb 2021 21:30:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210208183721.GB68242@xz-x1> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eric.auger@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.57, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.265, 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" , Jean-Philippe Brucker , Greg Kurz , qemu-devel@nongnu.org, Eugenio Perez Martin , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, [Adding David and Greg in CC] On 2/8/21 7:37 PM, Peter Xu wrote: > On Mon, Feb 08, 2021 at 11:21:23AM +0800, Jason Wang wrote: > > [...] > >>> I'm not sure I remember it right, but we seem to have similar discussion >>> previously on "what if the user didn't specify ats=on" - I think at that time >>> the conclusion was that we ignore the failure since that's not a valid >>> configuration for qemu. >> >> >> Yes, but I think I was wrong at that time. > > I can't say you're wrong - I actually still agree with you that at least > there's a priority of things we'd do, and this one is not extremely important > if that's not a major use case (say, if you will 100% always suggest an user to > use ats=on for a viommu enabled vhost). > >>> >>> The other issue I'm worried is (I think I mentioned it somewhere, but just to >>> double confirm): I'd like to make sure SMMU and virtio-iommu are the only IOMMU >>> platform that will use vhost. >> >> >> For upstream, it won't be easy :) > > Sorry I definitely didn't make myself clear... :) > > To be explicit, does ppc use vhost kernel too? Since I know at least ppc has > its own translation unit and its iommu notifier in qemu, so I'm unsure whether > the same patch would break ppc too, because vhost could also ignore all UNMAP > sent by the ppc vIOMMU. > >> >> >>> Otherwise IIUC we need to fix those vIOMMUs too. >> >> >> Right, last time I check AMD IOMMU emulation, it simply trigger device IOTLB >> invalidation during IOTLB invalidation which looks wrong. > > I did quickly grep IOMMU_NOTIFIER_UNMAP in amd_iommu.c and saw nothing. It > seems amd iommu is not ready for any kind of IOMMU notifiers yet. for context, we experienced a regression with vsmmuv3/vhost and virtio-iommu/vhost integration. We wondered whether the ppc viommu is able to protect vhost devices and if this relies on legacy IOMMU_NOTIFIER_UNMAP notifiers. ie. vhost does not register this notifier anymore but instead register dev-iotlb unmap notifier. Thanks Eric > > Thanks, >