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2025-02-13rust: qom: allow initializing interface vtablesPaolo Bonzini1-2/+43
Unlike regular classes, interface vtables can only be obtained via object_class_dynamic_cast. Provide a wrapper that allows accessing the vtable and pass it to a ClassInitImpl implementation, for example ClassInitImpl<ResettableClass>. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-02-13rust: qom: add object creation functionalityPaolo Bonzini1-2/+21
The basic object lifecycle test can now be implemented using safe code! Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-02-13rust: qom: add reference counting functionalityPaolo Bonzini1-5/+161
Add a smart pointer that allows to add and remove references from QOM objects. It's important to note that while all QOM objects have a reference count, in practice not all of them have their lifetime guarded by it. Embedded objects, specifically, are confined to the lifetime of the owner. When writing Rust bindings this is important, because embedded objects are *never* used through the "Owned<>" smart pointer that is introduced here. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-01-23rust: prefer NonNull::new to assertionsPaolo Bonzini1-8/+13
Do not use new_unchecked; the effect is the same, but the code is easier to read and unsafe regions become smaller. Likewise, NonNull::new can be used instead of assertion and followed by as_ref() or as_mut() instead of dereferencing the pointer. Suggested-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-01-10rust: qom: make INSTANCE_POST_INIT take a shared referencePaolo Bonzini1-6/+2
Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-01-10rust: qom: automatically use Drop trait to implement instance_finalizePaolo Bonzini1-2/+11
Replace the customizable INSTANCE_FINALIZE with a generic function that drops the Rust object. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-01-10rust: qom: add ParentFieldPaolo Bonzini1-6/+58
Add a type that, together with the C function object_deinit, ensures the correct drop order for QOM objects relative to their superclasses. Right now it is not possible to implement the Drop trait for QOM classes that are defined in Rust, as the drop() function would not be called when the object goes away; instead what is called is ObjectImpl::INSTANCE_FINALIZE. It would be nice for INSTANCE_FINALIZE to just drop the object, but this has a problem: suppose you have pub struct MySuperclass { parent: DeviceState, field: Box<MyData>, ... } impl Drop for MySuperclass { ... } pub struct MySubclass { parent: MySuperclass, ... } and an instance_finalize implementation that is like unsafe extern "C" fn drop_object<T: ObjectImpl>(obj: *mut Object) { unsafe { std::ptr::drop_in_place(obj.cast::<T>()) } } When instance_finalize is called for MySubclass, it will walk the struct's list of fields and call the drop method for MySuperclass. Then, object_deinit recurses to the superclass and calls the same drop method again. This will cause double-freeing of the Box<Data>. What's happening here is that QOM wants to control the drop order of MySuperclass and MySubclass's fields. To do so, the parent field must be marked ManuallyDrop<>, which is quite ugly. Instead, add a wrapper type ParentField<> that is specific to QOM. This hides the implementation detail of *what* is special about the ParentField, and will also be easy to check in the #[derive(Object)] macro. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-12-19rust: qom: add initial subset of methods on ObjectPaolo Bonzini1-3/+53
Add an example of implementing instance methods and converting the result back to a Rust type. In this case the returned types are a string (actually a Cow<str>; but that's transparent as long as it derefs to &str) and a QOM class. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-12-19rust: qom: add casting functionalityPaolo Bonzini1-7/+276
Add traits that let client cast typecast safely between object types. In particular, an upcast is compile-time guaranteed to succeed, and a YOLO C-style downcast must be marked as unsafe. The traits are based on an IsA<> trait that declares what is a subclass of what, which is an idea taken from glib-rs (https://docs.rs/glib/latest/glib/object/trait.IsA.html). The four primitives are also taken from there (https://docs.rs/glib/latest/glib/object/trait.Cast.html). However, the implementation of casting itself is a bit different and uses the Deref trait. This removes some pointer arithmetic from the pl011 device; it is also a prerequisite for the definition of methods, so that they can be invoked on all subclass structs. This will use the IsA<> trait to detect the structs that support the methods. glib also has a "monadic" casting trait which could be implemented on Option (as in https://docs.rs/glib/latest/glib/object/trait.CastNone.html) and perhaps even Result. For now I'm leaving it out, as the patch is already big enough and the benefit seems debatable. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-12-19rust: re-export C types from qemu-api submodulesPaolo Bonzini1-5/+7
Long term we do not want device code to use "bindings" at all, so make it possible to get the relevant types from the other modules of qemu-api. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-12-19rust: rename qemu-api modules to follow C code a bit morePaolo Bonzini1-0/+263
A full match would mean calling them qom::object and hw::core::qdev. For now, keep the names shorter but still a bit easier to find. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>