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* rust: qom: change instance_init to take a ParentInit<>Paolo Bonzini2025-06-171-3/+6
| | | | | | | | | | | | | This removes undefined behavior associated to writing to uninitialized fields, and makes it possible to remove "unsafe" from the instance_init implementation. However, the init function itself is still unsafe, because it must promise (as a sort as MaybeUninit::assume_init) that all fields have been initialized. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: make ParentInit lifetime-invariantPaolo Bonzini2025-06-171-4/+85
| | | | | | | | | | | | This is the trick that allows the parent-field initializer to be used only for the object that it's meant to be initialized. This way, the owner of a MemoryRegion must be the object that embeds it. More information is in the comments; it's best explained with a simplified example. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: introduce ParentInitPaolo Bonzini2025-06-171-1/+95
| | | | | | | | | This is a smart pointer for MaybeUninit; it can be upcasted to the already-initialized parent classes, or dereferenced to a MaybeUninit for the class that is being initialized. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: Fix the typos in docZhao Liu2025-05-261-2/+2
| | | | | | | | | These typos are found by "cargo spellcheck". Though it outputs a lot of noise and false positives, there still are some real typos. Signed-off-by: Zhao Liu <zhao1.liu@intel.com> Link: https://lore.kernel.org/r/20250520152750.2542612-6-zhao1.liu@intel.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: enable clippy::ptr_cast_constnessPaolo Bonzini2025-05-061-2/+2
| | | | | | Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org> Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: fix TODO about zeroability of classesPaolo Bonzini2025-05-061-3/+4
| | | | | | | | | | | | | | | The proposed suggestion is not correct. First it is not necessary for *all* classes to be Zeroable, only for Rust-defined ones; classes defined in C never implement ObjectImpl. Second, the parent class field need not be Zeroable. For example, ChardevClass's chr_write and chr_be_event fields cannot be NULL, therefore ChardevClass cannot be Zeroable. However, char_class_init() initializes them, therefore ChardevClass could be subclassed by Rust code. Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org> Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: use std::ffi instead of std::os::rawPaolo Bonzini2025-05-061-2/+1
| | | | | | | | This is allowed since Rust 1.64.0. Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org> Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* qom: Constify TypeInfo::interfacesPhilippe Mathieu-Daudé2025-04-251-1/+1
| | | | | | Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> Message-Id: <20250424194905.82506-6-philmd@linaro.org>
* qom: Constify TypeInfo::class_dataPhilippe Mathieu-Daudé2025-04-251-1/+1
| | | | | | | | All callers now correctly expect a const class data. Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20250424194905.82506-5-philmd@linaro.org>
* qom: Have class_init() take a const data argumentPhilippe Mathieu-Daudé2025-04-251-1/+1
| | | | | | | | | | Mechanical change using gsed, then style manually adapted to pass checkpatch.pl script. Suggested-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20250424194905.82506-4-philmd@linaro.org>
* qom: Have class_base_init() take a const data argumentPhilippe Mathieu-Daudé2025-04-251-1/+1
| | | | | | Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20250424194905.82506-3-philmd@linaro.org>
* rust: qom: remove operations on &mutPaolo Bonzini2025-03-061-83/+0
| | | | | | | | | | The dubious casts of mutable references to objects are not used anymore: the wrappers for qdev_init_clock_in and for IRQ and MMIO initialization can be called directly on the subclasses, without casts, plus they take a shared reference so they can just use "upcast()" instead of "upcast_mut()". Remove them. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: wrap Object with Opaque<>Paolo Bonzini2025-03-061-13/+22
| | | | | Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: get rid of ClassInitImplPaolo Bonzini2025-02-251-95/+69
| | | | | | | | Complete the conversion from the ClassInitImpl trait to class_init() methods. This will provide more freedom to split the qemu_api crate in separate parts. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: add ObjectImpl::CLASS_INITPaolo Bonzini2025-02-251-3/+11
| | | | | | | | | | | | | | | | | | | As shown in the PL011 device, the orphan rules required a manual implementation of ClassInitImpl for anything not in the qemu_api crate; this gets in the way of moving system emulation-specific code (including DeviceClass, which as a blanket ClassInitImpl<DeviceClass> implementation) into its own crate. Make ClassInitImpl optional, at the cost of having to specify the CLASS_INIT member by hand in every implementation of ObjectImpl. The next commits will get rid of it, replacing all the "impl<T> ClassInitImpl<Class> for T" blocks with a generic class_init<T> method on Class. Right now the definition is always the same, but do not provide a default as that will not be true once ClassInitImpl goes away. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: add IsA bounds to QOM implementation traitsPaolo Bonzini2025-02-251-1/+3
| | | | | | | | | | Check that the right bounds are provided to the qom_isa! macro whenever the class is defined to implement a certain class. This removes the need to add IsA<> bounds together with the *Impl trait bounds. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: allow initializing interface vtablesPaolo Bonzini2025-02-131-2/+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>
* rust: qom: add object creation functionalityPaolo Bonzini2025-02-131-2/+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>
* rust: qom: add reference counting functionalityPaolo Bonzini2025-02-131-5/+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>
* rust: prefer NonNull::new to assertionsPaolo Bonzini2025-01-231-8/+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>
* rust: qom: make INSTANCE_POST_INIT take a shared referencePaolo Bonzini2025-01-101-6/+2
| | | | | Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* rust: qom: automatically use Drop trait to implement instance_finalizePaolo Bonzini2025-01-101-2/+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>
* rust: qom: add ParentFieldPaolo Bonzini2025-01-101-6/+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>
* rust: qom: add initial subset of methods on ObjectPaolo Bonzini2024-12-191-3/+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>
* rust: qom: add casting functionalityPaolo Bonzini2024-12-191-7/+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>
* rust: re-export C types from qemu-api submodulesPaolo Bonzini2024-12-191-5/+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>
* rust: rename qemu-api modules to follow C code a bit morePaolo Bonzini2024-12-191-0/+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>