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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id C9D33CE79CE for ; Wed, 20 Sep 2023 13:02:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qiwqM-0003VP-KL; Wed, 20 Sep 2023 09:02:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qiwqL-0003Qf-Gm for qemu-devel@nongnu.org; Wed, 20 Sep 2023 09:02:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qiwqJ-0007Av-F7 for qemu-devel@nongnu.org; Wed, 20 Sep 2023 09:02:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695214930; h=from:from:reply-to: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=pn9tQFZSmkS90/ZhO+Tany+xtrvcQ5vG8LuN7U7+Xek=; b=Yqtn1fNLEAW0SgMSPPSHoTiWY4ZYe3rSAcniwnMuvNOu3Kui0KV7d8R3+OzgieYkBD8M4S 4NFW+jxjpD6fnEl1gdMIaD6OSGH6xS4P1XuePVTfvQpDIeGFZTz/HPBbwjVeVDoJpt4D9L D7m4dpyytxIz/yyGX0v1aLwa/I2LrhQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-649-pvpa_F3IMmKluyHG_TXq3A-1; Wed, 20 Sep 2023 09:02:06 -0400 X-MC-Unique: pvpa_F3IMmKluyHG_TXq3A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BB6F2100E2E1; Wed, 20 Sep 2023 13:02:05 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.35]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 005AC40C2009; Wed, 20 Sep 2023 13:01:46 +0000 (UTC) Date: Wed, 20 Sep 2023 14:01:39 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Jason Gunthorpe Cc: =?utf-8?Q?C=C3=A9dric?= Le Goater , "Duan, Zhenzhong" , "qemu-devel@nongnu.org" , "alex.williamson@redhat.com" , "nicolinc@nvidia.com" , "Martins, Joao" , "eric.auger@redhat.com" , "peterx@redhat.com" , "jasowang@redhat.com" , "Tian, Kevin" , "Liu, Yi L" , "Sun, Yi Y" , "Peng, Chao P" , Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Thomas Huth , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v1 15/22] Add iommufd configure option Message-ID: References: <20230830103754.36461-1-zhenzhong.duan@intel.com> <20230830103754.36461-16-zhenzhong.duan@intel.com> <75c9c56e-f2da-f2a3-32b6-c9228678b05a@redhat.com> <664d3338-c280-6d16-b03e-bb235931ce99@redhat.com> <20230920125103.GS13733@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230920125103.GS13733@nvidia.com> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Sep 20, 2023 at 09:51:03AM -0300, Jason Gunthorpe wrote: > On Wed, Sep 20, 2023 at 02:19:42PM +0200, Cédric Le Goater wrote: > > On 9/20/23 05:42, Duan, Zhenzhong wrote: > > > > > > > > > > -----Original Message----- > > > > From: Cédric Le Goater > > > > Sent: Wednesday, September 20, 2023 1:08 AM > > > > Subject: Re: [PATCH v1 15/22] Add iommufd configure option > > > > > > > > On 8/30/23 12:37, Zhenzhong Duan wrote: > > > > > This adds "--enable-iommufd/--disable-iommufd" to enable or disable > > > > > iommufd support, enabled by default. > > > > > > > > Why would someone want to disable support at compile time ? It might > > > > > > For those users who only want to support legacy container feature? > > > Let me know if you still prefer to drop this patch, I'm fine with that. > > > > I think it is too early. > > > > > > have been useful for dev but now QEMU should self-adjust at runtime > > > > depending only on the host capabilities AFAIUI. Am I missing something ? > > > > > > IOMMUFD doesn't support all features of legacy container, so QEMU > > > doesn't self-adjust at runtime by checking if host supports IOMMUFD. > > > We need to specify it explicitly to use IOMMUFD as below: > > > > > > -object iommufd,id=iommufd0 > > > -device vfio-pci,host=0000:02:00.0,iommufd=iommufd0 > > > > OK. I am not sure this is the correct interface yet. At first glance, > > I wouldn't introduce a new object for a simple backend depending on a > > kernel interface. I would tend to prefer a "iommu-something" property > > of the vfio-pci device with string values: "legacy", "iommufd", "default" > > and define the various interfaces (the ops you proposed) for each > > depending on the user preference and the capabilities of the host and > > possibly the device. > > I think the idea came from Alex? The major point is to be able to have > libvirt open /dev/iommufd and FD pass it into qemu and then share that > single FD across all VFIOs. qemu will typically not be able to > self-open /dev/iommufd as it is root-only. > > So the object is not exactly for the backend, the object is for the > file descriptor. Assuming we must have the exact same FD used for all vfio-pci devices, then using -object iommufd is the least worst way to get that FD injected into QEMU from libvirt. It is a little sucky in that when hotplugging/unplugging devices, libvirt has to think about whether or not it has to object_add/object_del the iommufd> again I don't see better options considering the need to have a single global FD. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|