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 043D8D149F3 for ; Fri, 25 Oct 2024 21:57:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t4SI4-0001MV-GX; Fri, 25 Oct 2024 17:56:16 -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 1t4SHz-0001M1-4G for qemu-devel@nongnu.org; Fri, 25 Oct 2024 17:56:11 -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 1t4SHx-0006op-Ct for qemu-devel@nongnu.org; Fri, 25 Oct 2024 17:56:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729893366; 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=FHPMo7dNj04ukn/DEUAyILsQbeciY5MqgtVnPEDVggE=; b=AyQWnRmuMUJMmBX8lzFRaxdt80Fxv3alSJGpavxBq1+bVQ/Dc3hXUSUv/NezQQKFCjWlh+ 0UvJRPDaiaItNE06iMRDnS/CZX+ufGlyRx+DOq+ICXTKfoDP8tXd49T7fC2OJkHpMAKoC2 RIaegylQw4hZYxerWWPGJ7huyhu1L+4= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-613-2T-25HilPRaVC4xNmb5EZw-1; Fri, 25 Oct 2024 17:56:04 -0400 X-MC-Unique: 2T-25HilPRaVC4xNmb5EZw-1 Received: by mail-qv1-f70.google.com with SMTP id 6a1803df08f44-6cc32a0b26bso33955546d6.1 for ; Fri, 25 Oct 2024 14:56:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729893364; x=1730498164; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=FHPMo7dNj04ukn/DEUAyILsQbeciY5MqgtVnPEDVggE=; b=IGUKIO7QxJXn+3buK1WXNvJYikRmP+yrWU59epqbZ9bW/gSPSlZoDirOCTfDWoLN/u kNob/DcgjQBtf8Yzdzu2xCPhLEdHjcIb1bMT8fv1/FTt2f9aM86UZ7Hl5vC3upf4mW3D qPV/aesMJ9fIOr6ddyU9IZAKZTe7rkgpSmCXMFcNtU1tbv6+U8ny4kod2IbgPIJYbiYr IoTCeMI1bEF0hkj4lciNZALppaeCulg0WeqX1D1aC7+tpup4/xsJ/ofFjSGZr9hhL9Zk cRz0+2tzH7q/oS7TTXxuBINNIe4PU0tHDDs9KAUq2w/4GPlGIz71NBNPaGPjstBdyOrP hm8g== X-Gm-Message-State: AOJu0Yx5OuL5IWqIM1hD/wBZ8GTZvTBI/uwORWQ9hz54ycQ3eRRlEZng Q51lDqKF/sXduEQ8M/ExJgMKwtZuKNBt3APWwGDVBbNskjiq+CuDLsUKlpLkvfJqgUl+BrEsnV9 9AeXrZTtcKWfWm4o1YAat8qRKtzS4IMx+3oAA/F5f3cs16HU9iRSQ X-Received: by 2002:a05:6214:3d0e:b0:6cb:eea5:69e0 with SMTP id 6a1803df08f44-6d1856f3c9bmr15814476d6.27.1729893363997; Fri, 25 Oct 2024 14:56:03 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGP/opelHhSkr0Waw8yYmlyfhGjAQbB1rfBviBwyXbARYJgSIlW/KrXXQoUYOV4sklcywUw3Q== X-Received: by 2002:a05:6214:3d0e:b0:6cb:eea5:69e0 with SMTP id 6a1803df08f44-6d1856f3c9bmr15814316d6.27.1729893363712; Fri, 25 Oct 2024 14:56:03 -0700 (PDT) Received: from x1n (pool-99-254-114-190.cpe.net.cable.rogers.com. [99.254.114.190]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d179a2d472sm9658486d6.128.2024.10.25.14.56.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Oct 2024 14:56:02 -0700 (PDT) Date: Fri, 25 Oct 2024 17:55:59 -0400 From: Peter Xu To: Markus Armbruster 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 , Eduardo Habkost , Daniel P =?utf-8?B?LiBCZXJyYW5nw6k=?= , 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> <87jzdwlekc.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87jzdwlekc.fsf@pond.sub.org> Received-SPF: pass client-ip=170.10.129.124; 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=-0.454, 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=-1.697, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Oct 25, 2024 at 11:25:23AM +0200, Markus Armbruster wrote: > Peter Xu writes: > > > 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. > > > > But with this, it should be closer to reach that goal to check singleton by > > QOM one day. > > > > Signed-off-by: Peter Xu > > $ qemu-system-x86_64 -device amd-iommu,help > /work/armbru/qemu/include/hw/boards.h:24:MACHINE: Object 0x56473906f960 is not an instance of type machine > Aborted (core dumped) > > (gdb) bt > #0 0x00007ffff4e43834 in __pthread_kill_implementation () at /lib64/libc.so.6 > #1 0x00007ffff4df18ee in raise () at /lib64/libc.so.6 > #2 0x00007ffff4dd98ff in abort () at /lib64/libc.so.6 > #3 0x0000555555f75ef3 in object_dynamic_cast_assert > (obj=0x555557e03960, typename=0x5555563c403e "machine", file=0x5555563c4018 "/work/armbru/qemu/include/hw/boards.h", line=24, func=0x5555563c4290 <__func__.7> "MACHINE") at ../qom/object.c:936 > #4 0x0000555555d5db0f in MACHINE (obj=0x555557e03960) > at /work/armbru/qemu/include/hw/boards.h:24 > #5 0x0000555555d5e030 in x86_iommu_get_default () at ../hw/i386/x86-iommu.c:83 > #6 0x0000555555d5e262 in x86_iommu_get_instance > (errp=0x5555573d4918 ) at ../hw/i386/x86-iommu.c:139 > #7 0x0000555555f7c27c in singleton_get_instance (class=0x555557e00320) > at ../qom/object_interfaces.c:371 > #8 0x000055555612a842 in qmp_device_list_properties > (typename=0x555557e001d0 "amd-iommu", errp=0x7fffffffda38) > at ../qom/qom-qmp-cmds.c:147 > #9 0x0000555555bf20b2 in qdev_device_help (opts=0x555557e001f0) > at ../system/qdev-monitor.c:314 > #10 0x0000555555bfe06d in device_help_func > (opaque=0x0, opts=0x555557e001f0, errp=0x0) at ../system/vl.c:1208 > #11 0x0000555556217186 in qemu_opts_foreach > (list=0x55555729e5c0 , func=0x555555bfe04d , opaque=0x0, errp=0x0) at ../util/qemu-option.c:1135 > #12 0x0000555555c01d56 in qemu_process_help_options () at ../system/vl.c:2555 > #13 0x0000555555c04d81 in qemu_init (argc=3, argv=0x7fffffffde28) > at ../system/vl.c:3654 > #14 0x000055555612ffae in main (argc=3, argv=0x7fffffffde28) > at ../system/main.c:47 > Thanks for the report! It turns out that qdev_get_machine() cannot be invoked too early, and the singleton code can make it earlier.. We may want a pre-requisite patch to allow qdev_get_machine() to be invoked anytime, like: ===8<=== diff --git a/hw/core/qdev.c b/hw/core/qdev.c index db36f54d91..7ceae47139 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -831,6 +831,16 @@ Object *qdev_get_machine(void) { static Object *dev; + if (!phase_check(PHASE_MACHINE_CREATED)) { + /* + * When the machine is not created, below can wrongly create + * /machine to be a container.. this enables qdev_get_machine() to + * be used at any time and return NULL properly when machine is not + * created. + */ + return NULL; + } + if (dev == NULL) { dev = container_get(object_get_root(), "/machine"); } ===8<=== I hope it makes sense on its own. Then callers who can be invoked earlier could then handle NULL properly, in this case.. ===8<=== diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c index 4bfeb08705..fceb7adfe0 100644 --- a/hw/i386/x86-iommu.c +++ b/hw/i386/x86-iommu.c @@ -80,9 +80,15 @@ void x86_iommu_irq_to_msi_message(X86IOMMUIrq *irq, MSIMessage *msg_out) X86IOMMUState *x86_iommu_get_default(void) { - MachineState *ms = MACHINE(qdev_get_machine()); - PCMachineState *pcms = - PC_MACHINE(object_dynamic_cast(OBJECT(ms), TYPE_PC_MACHINE)); + Object *machine = qdev_get_machine(); + PCMachineState *pcms; + + /* If machine has not been created, so is the vIOMMU */ + if (!machine) { + return NULL; + } + + pcms = PC_MACHINE(object_dynamic_cast(machine, TYPE_PC_MACHINE)); if (pcms && object_dynamic_cast(OBJECT(pcms->iommu), TYPE_X86_IOMMU_DEVICE)) { ===8<=== I'll make sure this works if I'll repost. Thanks, -- Peter Xu