Avoid duplicated code to retrieve the QOM type strings from the
Rust type.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Define a separate trait for fields that also applies to classes that are
defined by C code. This makes it possible to add metadata to core classes,
which has multiple uses:
- it makes it possible to access the parent struct's TYPE_* for types
that are defined in Rust code, and to avoid repeating it in every subclass
- implementors of ObjectType will be allowed to implement the IsA<> trait and
therefore to perform typesafe casts from one class to another.
- in the future, an ObjectType could be created with Foo::new() in a type-safe
manner, without having to pass a TYPE_* constant.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allow the ObjectImpl trait to expose Rust functions that avoid raw
pointers (though INSTANCE_INIT for example is still unsafe).
ObjectImpl::TYPE_INFO adds thunks around the functions in
ObjectImpl.
While at it, document `TypeInfo`.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allow the DeviceImpl trait to expose safe Rust functions.
rust_device_class_init<> adds thunks around the functions
in DeviceImpl.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use a trait to access the former parameters to device_class_init!.
This allows hiding the details of the class_init implementation behind
a generic function and makes higher-level functionality available from
qemu_api.
The implementation of ClassInitImpl is then the same for all devices and
is easily macroized. Later on, we can remove the need to implement
ClassInitImpl by hand for all device types, and stop making
rust_device_class_init<>() public.
While at it, document the members of DeviceImpl.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Put all traits on the instance struct, which makes it possible to reuse
class structs if no new virtual methods or class fields are added.
This is almost always the case for devices (because they are leaf
classes), which is the primary use case for Rust.
This is also simpler: soon we will find the implemented methods without
macros, and this removes the need to go from the class struct to the
instance struct to find the implementation of the *Impl traits.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
type_info! is only used in the definition of ObjectImpl::TYPE_INFO, and
in fact in all of them. Pull type_info!'s definition into the ObjectImpl
trait, thus simplifying the external interface of qemu_api::definitions.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The bindgen supports `static inline` function binding since v0.64.0 as
an experimental feature (`--wrap-static-fns`), and stabilizes it after
v0.70.0.
But the oldest version of bindgen supported by QEMU is v0.60.1, so
there's no way to generate the binding for deposit64() which is `static
inline` (in include/qemu/bitops.h).
Instead, implement it by hand in Rust and make it available for all
unsigned types through an IntegerExt trait. Since it only involves bit
operations, the Rust version of the code is almost identical to the
original C version, but it applies to more types than just u64.
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Co-authored-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The InterruptSource bindings let us call qemu_set_irq() and sysbus_init_irq()
as safe code.
Interrupt sources, qemu_irq in C code, are pointers to IRQState objects.
They are QOM link properties and can be written to outside the control
of the device (i.e. from a shared reference); therefore they must be
interior-mutable in Rust. Since thread-safety is provided by the BQL,
what we want here is the newly-introduced BqlCell. A pointer to the
contents of the BqlCell (an IRQState**, or equivalently qemu_irq*)
is then passed to the C sysbus_init_irq function.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a module that will contain frequently used traits and
occasionally structs. They can be included quickly with
"use qemu_api::prelude::*".
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Similar to the existing BqlCell, introduce a custom interior mutability
primitive that resembles RefCell but accounts for QEMU's threading model.
Borrowing the RefCell requires proving that the BQL is held, and
attempting to access without the BQL is a runtime panic.
Almost all of the code was taken from Rust's standard library, while
removing unstable features and probably-unnecessary functionality that
amounts to 60% of the original code. A lot of what's left is documentation,
as well as unit tests in the form of doctests. These are not yet integrated
in "make check" but can be run with "cargo test --doc".
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
QEMU objects usually have their pointer shared with the "outside
world" very early in their lifetime, for example when they create their
MemoryRegions. Because at this point it is not valid anymore to
create a &mut reference to the device, individual parts of the
device struct must be made mutable in a controlled manner.
QEMU's Big Lock (BQL) effectively turns multi-threaded code into
single-threaded code while device code runs, as long as the BQL is not
released while the device is borrowed (because C code could sneak in and
mutate the device). We can then introduce custom interior mutability primitives
that are semantically similar to the standard library's (single-threaded)
Cell and RefCell, but account for QEMU's threading model. Accessing
the "BqlCell" or borrowing the "BqlRefCell" requires proving that the
BQL is held, and attempting to access without the BQL is a runtime panic,
similar to RefCell's already-borrowed panic.
With respect to naming I also considered omitting the "Bql" prefix or
moving it to the module, e.g. qemu_api::bql::{Cell, RefCell}. However,
this could easily lead to mistakes and confusion; for example rustc could
suggest the wrong import, leading to subtle bugs.
As a start introduce the an equivalent of Cell. Almost all of the code
was taken from Rust's standard library, while removing unstable features
and probably-unnecessary functionality that constitute a large of the
original code. A lot of what's left is documentation, as well as unit
tests in the form of doctests. These are not yet integrated in "make
check" but can be run with "cargo test --doc".
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For the matcher of macro, "expr" is used for expressions, while "ident"
is used for variable/function names, and "ty" matches types.
In define_property macro, $field is a member name of type $state, so it
should be defined as "ident", though offset_of! doesn't complain about
this. $type is the type of $field, since it is not used in the macro, so
that no type mismatch error is triggered either.
Fix fragment-specifiers of $field and $type.
Signed-off-by: Junjie Mao <junjie.mao@hotmail.com>
Co-developed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20241017143245.1248589-2-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Abstract common invocations of "cargo", that do not require copying
the generated bindgen file or setting up MESON_BUILD_ROOT.
In the future these could also do completely without cargo and invoke
the underlying programs directly.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Many lints that default to allow can be helpful in detecting bugs or
keeping the code style homogeneous. Add them liberally, though perhaps
not as liberally as in hw/char/pl011/src/lib.rs. In particular, enabling
entire groups can be problematic because of bitrot when new links are
added in the future.
For Clippy, this is actually a feature that is only present in Cargo
1.74.0 but, since we are not using Cargo to *build* QEMU, only developers
will need a new-enough cargo and only to run tools such as clippy.
The requirement does not apply to distros that are building QEMU.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These are reported as clippy::semicolon_inside_block and clippy::as_ptr_cast_mut.
clippy::semicolon_inside_block can be configured not to lint single-line
blocks; just go with the default.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
An extra benefit of workspaces is that they allow to place lint level
settings in a single Cargo.toml; the settings are then inherited by
packages in the workspace.
Correspondingly, teach rustc_args.py to get the unexpected_cfgs
configuration from the workspace Cargo.toml.
Note that it is still possible to allow or deny warnings per crate or
module, via the #![] attribute syntax. The rust/qemu-api/src/bindings.rs
file is an example.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cargo.toml makes it possible to describe the desired lint level settings
in a nice format. We can extend this to Meson-built crates, by teaching
rustc_args.py to fetch lint and --check-cfg arguments from Cargo.toml.
--check-cfg arguments come from the unexpected_cfgs lint as well as crate
features
Start with qemu-api, since it already has a [lints.rust] table and
an invocation of rustc_args.py.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Parse the Cargo.toml file, looking for the unexpected_cfgs
configuration. When generating --cfg options from the
config-host.h file, only use those that are included in the
configuration.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Only qemu-api needs access to the symbols in config-host.h. Remove
the temptation to use them elsewhere by limiting the --cfg arguments to
the qemu-api crate.
Per-crate invocation of the script will also be needed to add --check-cfg
options for each crate's features (when more complex, build-time
configurable devices are added in the future).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Right now, using cargo with QEMU requires copying by hand the bindings.rs to the
source tree. Instead, we can use an include file to escape the cage of cargo's
mandated source directory structure.
By running cargo within meson's "devenv" and adding a MESON_BUILD_ROOT
environment variable, it is easy for build.rs to find the file. However, the
file must be symlinked into cargo's output directory for rust-analyzer to find
it.
Suggested-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We might have more uses for --cfg MESON, even though right now it's only
qemu-api that has generated files. Since we're going to add more flags
to the add_project_arguments calls for Rust, it makes sense to also add
--cfg MESON everywhere.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
--generate-cstr is a good idea and generally the right thing to do,
but it is not available in Debian 12 and Ubuntu 22.04. Work around
the absence.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MaybeUninit::zeroed() is handy but is not available as a "const" function
until Rust 1.75.0.
Remove the default implementation of Zeroable::ZERO, and write by hand
the definitions for those types that need it. It may be possible to
add automatic implementation of the trait, via a procedural macro and/or
a trick similar to offset_of!, but do it the easy way for now.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
offset_of! was stabilized in Rust 1.77.0. Use an alternative implemenation
that was found on the Rust forums, and whose author agreed to license as
MIT for use in QEMU.
The alternative allows only one level of field access, but apart
from this can be used just by replacing core::mem::offset_of! with
qemu_api::offset_of!.
The actual implementation of offset_of! is done in a declarative macro,
but for simplicity and to avoid introducing an extra level of indentation,
the trigger is a procedural macro #[derive(offsets)].
The procedural macro is perhaps a bit overengineered, but it helps
introducing some idioms that will be useful in the future as well.
Signed-off-by: Junjie Mao <junjie.mao@hotmail.com>
Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Workspaces allows tracking dependencies for multiple crates at once,
by having a single Cargo.lock file at the top of the rust/ tree.
Because QEMU's Cargo.lock files have to be synchronized with the versions
of crates in subprojects/, using a workspace avoids the need to copy
over the Cargo.lock file when adding a new device (and thus a new crate)
under rust/hw/.
In addition, workspaces let cargo download and build dependencies just
once. While right now we have one leaf crate (hw/char/pl011), this
will not be the case once more devices are added.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The next commit will introduce a new build.rs dependency for rust/qemu-api,
version_check. Before adding it, ensure that all dependencies are
synchronized between the Meson- and cargo-based build systems.
Note that it's not clear whether in the long term we'll use Cargo for
anything; it seems that the three main uses (clippy, rustfmt, rustdoc)
can all be invoked manually---either via glue code in QEMU, or by
extending Meson to gain the relevant functionality. However, for
the time being we're stuck with Cargo so it should at least look at
the same code as the rest of the build system.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This allows CStr constants to be defined easily on Rust 1.63.0, while
checking that there are no embedded NULs. c"" literals were only
stabilized in Rust 1.77.0.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
core::ffi::c_* types were introduced in Rust 1.64.0. Use the older types
in std::os::raw, which are now aliases of the types in core::ffi. There is
no need to compile QEMU as no_std, so this is acceptable as long as we support
a version of Debian with Rust 1.63.0.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new qemu_api module, `vmstate`. Declare a bunch of Rust
macros declared that are equivalent in spirit to the C macros in
include/migration/vmstate.h.
For example the Rust of equivalent of the C macro:
VMSTATE_UINT32(field_name, struct_name)
is:
vmstate_uint32!(field_name, StructName)
This breathtaking development will allow us to reach feature parity between
the Rust and C pl011 implementations.
Extracted from a patch by Manos Pitsidianakis
(https://lore.kernel.org/qemu-devel/20241024-rust-round-2-v1-4-051e7a25b978@linaro.org/).
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MaybeUninit::zeroed() is handy, but it introduces unsafe (and has a
pretty heavy syntax in general). Introduce a trait that provides the
same functionality while staying within safe Rust.
In addition, MaybeUninit::zeroed() is not available as a "const"
function until Rust 1.75.0, so this also prepares for having handwritten
implementations of the trait until we can assume that version.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that device_class_set_props() takes a const pointer, the only part of
"define_property!" that needs to be non-const is the call to try_into().
This in turn will only break if offset_of returns a value with the most
significant bit set (i.e. a struct size that is >=2^31 or >= 2^63,
respectively on 32- and 64-bit system), which is impossible.
Just use a cast and clean everything up to remove the run-time
initialization. This also removes a use of OnceLock, which was only
stabilized in 1.70.0.
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use the "struct update" syntax to initialize most of the fields to zero,
and simplify the handmade type-checking of $name.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the duplicate code by using the module_init! macro; at the same time,
simplify how module_init! is used, by taking inspiration from the implementation
of #[derive(Object)].
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Adjust the integration test to compile with a subset of QEMU object
files, and make it actually create an object of the class it defines.
Follow the Rust filesystem conventions, where tests go in tests/ if
they use the library in the same way any other code would.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Some newer ABI implementations do not provide .ctors; and while
some linkers rewrite .ctors into .init_array, not all of them do.
Use the newer .init_array ABI, which works more reliably, and
apply it to all non-Apple, non-Windows platforms.
This is similar to how the ctor crate operates; without this change,
"#[derive(Object)]" does not work on Fedora 41.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Mangled symbols do not cause any issue; disabling mangling is only useful if
C headers reference the Rust function, which is not the case here.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is not necessary and makes it harder to write code that is
portable between 32- and 64-bit systems: it adds extra casts even
though size_of, align_of or offset_of already return the right type.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
rustc_args is needed to smooth the difference in warnings between the various
versions of rustc. Always include those arguments.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit adds a helper crate library, qemu-api-macros for derive (and
other procedural) macros to be used along qemu-api.
It needs to be a separate library because in Rust, procedural macros, or
macros that can generate arbitrary code, need to be special separate
compilation units.
Only one macro is introduced in this patch, #[derive(Object)]. It
generates a constructor to register a QOM TypeInfo on init and it must
be used on types that implement qemu_api::definitions::ObjectImpl trait.
Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Link: https://lore.kernel.org/r/dd645642406a6dc2060c6f3f17db2bc77ed67b59.1727961605.git.manos.pitsidianakis@linaro.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add rust/qemu-api, which exposes rust-bindgen generated FFI bindings and
provides some declaration macros for symbols visible to the rest of
QEMU.
Co-authored-by: Junjie Mao <junjie.mao@intel.com>
Co-authored-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Link: https://lore.kernel.org/r/0fb23fbe211761b263aacec03deaf85c0cc39995.1727961605.git.manos.pitsidianakis@linaro.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini
Junjie Mao
Manos Pitsidianakis