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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-46132292c97sm48481691cf.49.2024.10.29.14.16.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Oct 2024 14:16:21 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Cc: Markus Armbruster , Peter Maydell , Eduardo Habkost , Paolo Bonzini , Mark Cave-Ayland , Igor Mammedov , "Michael S . Tsirkin" , Alex Williamson , "Dr . David Alan Gilbert" , peterx@redhat.com, =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= , =?utf-8?q?Phi?= =?utf-8?q?lippe_Mathieu-Daud=C3=A9?= , =?utf-8?q?C=C3=A9?= =?utf-8?q?dric_Le_Goater?= , Fabiano Rosas , Juraj Marcin Subject: [PATCH RFC v2 5/7] x86/iommu: Make x86-iommu a singleton object Date: Tue, 29 Oct 2024 17:16:05 -0400 Message-ID: <20241029211607.2114845-6-peterx@redhat.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20241029211607.2114845-1-peterx@redhat.com> References: <20241029211607.2114845-1-peterx@redhat.com> MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@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_H3=0.001, RCVD_IN_MSPIKE_WL=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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. Note: after this patch, x86_iommu_get_default() might be called very early, even before machine is created (e.g., cmdline "-device intel-iommu,help"). In this case we need to be prepared with such, and that also means the default iommu is not yet around. Signed-off-by: Peter Xu --- hw/i386/x86-iommu.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c index 60af896225..ec45b80306 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) @@ -79,9 +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)) { @@ -133,10 +140,19 @@ static Property x86_iommu_properties[] = { DEFINE_PROP_END_OF_LIST(), }; +static Object *x86_iommu_get_instance(void) +{ + return object_ref(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 +168,10 @@ 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)