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 B2E86D2AB1C for ; Tue, 29 Oct 2024 10:47:58 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t5jky-0000Nh-Lf; Tue, 29 Oct 2024 06:47:24 -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 1t5jkx-0000NX-Cb for qemu-devel@nongnu.org; Tue, 29 Oct 2024 06:47:23 -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 1t5jkv-0006AM-CI for qemu-devel@nongnu.org; Tue, 29 Oct 2024 06:47:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730198838; 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:in-reply-to:in-reply-to: references:references; bh=UPqKpRx5HMUdVVVLLpOt3awRChRdkNU4KIJ06L7B8KY=; b=L/TfnoYyRyeo8ZJ/jyL9YMRBNZwTRjDqw9/z+CLbps/6DsJF5YUZ0oiku5/rf+VTLwVDa9 ThLxZxB1e4KrzO4SoV8EmvARe80seHPswxvN+Qd5Aj2BVUIgy4gADh/ZzC3mfvcn2xgtbE Ib8iQcf+N3MEFX6nahFl9h8zpSWBgfg= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-515-K5ipStexNUalZyBtMz1zrw-1; Tue, 29 Oct 2024 06:47:15 -0400 X-MC-Unique: K5ipStexNUalZyBtMz1zrw-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9AFD01955EEA; Tue, 29 Oct 2024 10:47:14 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.142]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 72E1719560AA; Tue, 29 Oct 2024 10:47:08 +0000 (UTC) Date: Tue, 29 Oct 2024 10:47:06 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Peter Xu Cc: qemu-devel@nongnu.org, Fabiano Rosas , Igor Mammedov , Juraj Marcin , "Michael S . Tsirkin" , "Dr . David Alan Gilbert" , =?utf-8?Q?C=C3=A9dric?= Le Goater , Markus Armbruster , Eduardo Habkost , Alex Williamson , Paolo Bonzini , Peter Maydell Subject: Re: [PATCH 2/4] x86/iommu: Make x86-iommu a singleton object Message-ID: References: <20241024165627.1372621-1-peterx@redhat.com> <20241024165627.1372621-3-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20241024165627.1372621-3-peterx@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 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: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.302, 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_H2=-0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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 Thu, Oct 24, 2024 at 12:56:25PM -0400, Peter Xu wrote: > X86 IOMMUs cannot be created more than one on a system yet. Make it a > singleton so it guards the system from accidentally create yet another > IOMMU object when one already presents. > > Now if someone tries to create more than one, e.g., via: > > ./qemu -M q35 -device intel-iommu -device intel-iommu > > The error will change from: > > qemu-system-x86_64: -device intel-iommu: QEMU does not support multiple vIOMMUs for x86 yet. > > To: > > qemu-system-x86_64: -device intel-iommu: Class 'intel-iommu' only supports one instance > > Unfortunately, yet we can't remove the singleton check in the machine > hook (pc_machine_device_pre_plug_cb), because there can also be > virtio-iommu involved, which doesn't share a common parent class yet. Presumably the 'class' reported is the one that the user requested, but this would imply if we were to do qemu-system-x86_64 -device intel-iommu -device virtio-iommu Then QEMU would report "Class 'virtio-iommu' only supports one instance" at which point the user is wondering, huh, I only requested one virtio-iommu instance ? IOW, the current error message would be better as it is not referring to a specific subclass, but rather to the more general fact that only a single IOMMU is permitted, no matter what it's impl is. > > But with this, it should be closer to reach that goal to check singleton by > QOM one day. > > Signed-off-by: Peter Xu > --- > hw/i386/x86-iommu.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c > index 60af896225..4bfeb08705 100644 > --- a/hw/i386/x86-iommu.c > +++ b/hw/i386/x86-iommu.c > @@ -26,6 +26,7 @@ > #include "qemu/error-report.h" > #include "trace.h" > #include "sysemu/kvm.h" > +#include "qom/object_interfaces.h" > > void x86_iommu_iec_register_notifier(X86IOMMUState *iommu, > iec_notify_fn fn, void *data) > @@ -133,10 +134,19 @@ static Property x86_iommu_properties[] = { > DEFINE_PROP_END_OF_LIST(), > }; > > +static Object *x86_iommu_get_instance(Error **errp) > +{ > + return OBJECT(x86_iommu_get_default()); > +} > + > static void x86_iommu_class_init(ObjectClass *klass, void *data) > { > DeviceClass *dc = DEVICE_CLASS(klass); > + SingletonClass *singleton = SINGLETON_CLASS(klass); > + > dc->realize = x86_iommu_realize; > + singleton->get_instance = x86_iommu_get_instance; > + > device_class_set_props(dc, x86_iommu_properties); > } > > @@ -152,6 +162,10 @@ static const TypeInfo x86_iommu_info = { > .class_init = x86_iommu_class_init, > .class_size = sizeof(X86IOMMUClass), > .abstract = true, > + .interfaces = (InterfaceInfo[]) { > + { TYPE_SINGLETON }, > + { } > + } > }; > > static void x86_iommu_register_types(void) > -- > 2.45.0 > 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 :|