rust: split "chardev" crate

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Link: https://lore.kernel.org/r/20250827104147.717203-14-marcandre.lureau@redhat.com
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/Cargo.lock

@@ -51,6 +51,18 @@ dependencies = [
  "migration",
 ]
 
+[[package]]
+name = "chardev"
+version = "0.1.0"
+dependencies = [
+ "bql",
+ "common",
+ "migration",
+ "qemu_api_macros",
+ "qom",
+ "util",
+]
+
 [[package]]
 name = "common"
 version = "0.1.0"
@@ -118,6 +130,7 @@ dependencies = [
  "bilge-impl",
  "bits",
  "bql",
+ "chardev",
  "common",
  "migration",
  "qemu_api",
@@ -163,6 +176,7 @@ name = "qemu_api"
 version = "0.1.0"
 dependencies = [
  "bql",
+ "chardev",
  "common",
  "migration",
  "qemu_api_macros",

rust/chardev/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "chardev"
+version = "0.1.0"
+description = "Rust bindings for QEMU/chardev"
+resolver = "2"
+publish = false
+
+authors.workspace = true
+edition.workspace = true
+homepage.workspace = true
+license.workspace = true
+repository.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+common = { path = "../common" }
+bql = { path = "../bql" }
+migration = { path = "../migration" }
+qom = { path = "../qom" }
+util = { path = "../util" }
+qemu_api_macros = { path = "../qemu-api-macros" }
+
+[lints]
+workspace = true

rust/chardev/build.rs

@@ -0,0 +1 @@
+../util/build.rs

rust/chardev/meson.build

@@ -0,0 +1,41 @@
+c_enums = [
+  'QEMUChrEvent',
+]
+_chardev_bindgen_args = []
+foreach enum : c_enums
+  _chardev_bindgen_args += ['--rustified-enum', enum]
+endforeach
+
+# TODO: Remove this comment when the clang/libclang mismatch issue is solved.
+#
+# Rust bindings generation with `bindgen` might fail in some cases where the
+# detected `libclang` does not match the expected `clang` version/target. In
+# this case you must pass the path to `clang` and `libclang` to your build
+# command invocation using the environment variables CLANG_PATH and
+# LIBCLANG_PATH
+_chardev_bindings_inc_rs = rust.bindgen(
+  input: 'wrapper.h',
+  dependencies: common_ss.all_dependencies(),
+  output: 'bindings.inc.rs',
+  include_directories: bindings_incdir,
+  bindgen_version: ['>=0.60.0'],
+  args: bindgen_args_common + _chardev_bindgen_args,
+)
+
+_chardev_rs = static_library(
+  'chardev',
+  structured_sources(
+    [
+      'src/lib.rs',
+      'src/bindings.rs',
+      'src/chardev.rs',
+    ],
+    {'.': _chardev_bindings_inc_rs}
+  ),
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  link_with: [_bql_rs, _migration_rs, _qom_rs, _util_rs],
+  dependencies: [common_rs, qemu_api_macros],
+)
+
+chardev_rs = declare_dependency(link_with: [_chardev_rs], dependencies: [qemu_api_macros, chardev, qemuutil])

rust/chardev/src/bindings.rs

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#![allow(
+    dead_code,
+    improper_ctypes_definitions,
+    improper_ctypes,
+    non_camel_case_types,
+    non_snake_case,
+    non_upper_case_globals,
+    unnecessary_transmutes,
+    unsafe_op_in_unsafe_fn,
+    clippy::pedantic,
+    clippy::restriction,
+    clippy::style,
+    clippy::missing_const_for_fn,
+    clippy::ptr_offset_with_cast,
+    clippy::useless_transmute,
+    clippy::missing_safety_doc,
+    clippy::too_many_arguments
+)]
+
+use common::Zeroable;
+
+#[cfg(MESON)]
+include!("bindings.inc.rs");
+
+#[cfg(not(MESON))]
+include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs"));
+
+// SAFETY: these are implemented in C; the bindings need to assert that the
+// BQL is taken, either directly or via `BqlCell` and `BqlRefCell`.
+// When bindings for character devices are introduced, this can be
+// moved to the Opaque<> wrapper in src/chardev.rs.
+unsafe impl Send for CharBackend {}
+unsafe impl Sync for CharBackend {}
+
+unsafe impl Zeroable for CharBackend {}

rust/chardev/src/lib.rs

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pub mod bindings;
+
+mod chardev;
+pub use chardev::*;

rust/chardev/wrapper.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/*
+ * This header file is meant to be used as input to the `bindgen` application
+ * in order to generate C FFI compatible Rust bindings.
+ */
+
+#ifndef __CLANG_STDATOMIC_H
+#define __CLANG_STDATOMIC_H
+/*
+ * Fix potential missing stdatomic.h error in case bindgen does not insert the
+ * correct libclang header paths on its own. We do not use stdatomic.h symbols
+ * in QEMU code, so it's fine to declare dummy types instead.
+ */
+typedef enum memory_order {
+  memory_order_relaxed,
+  memory_order_consume,
+  memory_order_acquire,
+  memory_order_release,
+  memory_order_acq_rel,
+  memory_order_seq_cst,
+} memory_order;
+#endif /* __CLANG_STDATOMIC_H */
+
+#include "qemu/osdep.h"
+
+#include "chardev/char-fe.h"
+#include "chardev/char-serial.h"

rust/hw/char/pl011/Cargo.toml

@@ -21,6 +21,7 @@ util = { path = "../../../util" }
 bql = { path = "../../../bql" }
 migration = { path = "../../../migration" }
 qom = { path = "../../../qom" }
+chardev = { path = "../../../chardev" }
 qemu_api = { path = "../../../qemu-api" }
 qemu_api_macros = { path = "../../../qemu-api-macros" }
 

rust/hw/char/pl011/meson.build

@@ -14,6 +14,7 @@ _libpl011_rs = static_library(
     bql_rs,
     qemu_api_macros,
     qom_rs,
+    chardev_rs,
   ],
 )
 

rust/hw/char/pl011/src/device.rs

@@ -5,13 +5,13 @@
 use std::{ffi::CStr, mem::size_of};
 
 use bql::BqlRefCell;
+use chardev::{CharBackend, Chardev, Event};
 use common::{static_assert, uninit_field_mut};
 use migration::{
     self, impl_vmstate_forward, impl_vmstate_struct, vmstate_fields, vmstate_of,
     vmstate_subsections, vmstate_unused, VMStateDescription, VMStateDescriptionBuilder,
 };
 use qemu_api::{
-    chardev::{CharBackend, Chardev, Event},
     irq::{IRQState, InterruptSource},
     memory::{hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder},
     prelude::*,

rust/meson.build

@@ -29,6 +29,7 @@ subdir('util')
 subdir('migration')
 subdir('bql')
 subdir('qom')
+subdir('chardev')
 subdir('qemu-api')
 
 subdir('hw')

rust/qemu-api/Cargo.toml

@@ -15,6 +15,7 @@ rust-version.workspace = true
 
 [dependencies]
 common = { path = "../common" }
+chardev = { path = "../chardev" }
 migration = { path = "../migration" }
 util = { path = "../util" }
 bql = { path = "../bql" }

rust/qemu-api/meson.build

@@ -7,7 +7,6 @@ c_enums = [
   'GpioPolarity',
   'MachineInitPhase',
   'MemoryDeviceInfoKind',
-  'QEMUChrEvent',
   'ResetType',
   'device_endian',
 ]
@@ -23,9 +22,10 @@ foreach enum : c_bitfields
 endforeach
 
 blocked_type = [
+  'Chardev',
+  'Error',
   'ObjectClass',
   'VMStateDescription',
-  'Error',
 ]
 foreach type: blocked_type
   _qemu_api_bindgen_args += ['--blocklist-type', type]
@@ -53,7 +53,6 @@ _qemu_api_rs = static_library(
     [
       'src/lib.rs',
       'src/bindings.rs',
-      'src/chardev.rs',
       'src/irq.rs',
       'src/memory.rs',
       'src/prelude.rs',
@@ -65,8 +64,8 @@ _qemu_api_rs = static_library(
   override_options: ['rust_std=2021', 'build.rust_std=2021'],
   rust_abi: 'rust',
   rust_args: _qemu_api_cfg,
-  dependencies: [anyhow_rs, bql_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros,
-                 qom_rs, util_rs, hwcore, chardev],
+  dependencies: [anyhow_rs, bql_rs, chardev_rs, common_rs, foreign_rs, libc_rs, migration_rs, qemu_api_macros,
+                 qom_rs, util_rs, hwcore],
 )
 
 qemu_api_rs = declare_dependency(link_with: [_qemu_api_rs],

rust/qemu-api/src/bindings.rs

@@ -20,6 +20,7 @@
 
 //! `bindgen`-generated declarations.
 
+use chardev::bindings::Chardev;
 use common::Zeroable;
 use migration::bindings::VMStateDescription;
 use qom::bindings::ObjectClass;
@@ -31,13 +32,6 @@ include!("bindings.inc.rs");
 #[cfg(not(MESON))]
 include!(concat!(env!("OUT_DIR"), "/bindings.inc.rs"));
 
-// SAFETY: these are implemented in C; the bindings need to assert that the
-// BQL is taken, either directly or via `BqlCell` and `BqlRefCell`.
-// When bindings for character devices are introduced, this can be
-// moved to the Opaque<> wrapper in src/chardev.rs.
-unsafe impl Send for CharBackend {}
-unsafe impl Sync for CharBackend {}
-
 // SAFETY: this is a pure data struct
 unsafe impl Send for CoalescedMemoryRange {}
 unsafe impl Sync for CoalescedMemoryRange {}
@@ -59,4 +53,3 @@ unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_1 {}
 unsafe impl Zeroable for crate::bindings::MemoryRegionOps__bindgen_ty_2 {}
 unsafe impl Zeroable for crate::bindings::MemoryRegionOps {}
 unsafe impl Zeroable for crate::bindings::MemTxAttrs {}
-unsafe impl Zeroable for crate::bindings::CharBackend {}

rust/qemu-api/src/lib.rs

@@ -13,7 +13,6 @@ pub mod bindings;
 #[rustfmt::skip]
 pub mod prelude;
 
-pub mod chardev;
 pub mod irq;
 pub mod memory;
 pub mod qdev;

rust/qemu-api/src/qdev.rs

@@ -10,6 +10,7 @@ use std::{
 };
 
 pub use bindings::{ClockEvent, DeviceClass, Property, ResetType};
+use chardev::Chardev;
 use common::{callbacks::FnCall, Opaque};
 use migration::{impl_vmstate_c_struct, VMStateDescription};
 use qom::{prelude::*, ObjectClass, ObjectImpl, Owned, ParentInit};
@@ -17,7 +18,6 @@ use util::{Error, Result};
 
 use crate::{
     bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, ResettableClass},
-    chardev::Chardev,
     irq::InterruptSource,
 };
 
@@ -137,8 +137,8 @@ unsafe impl QDevProp for u64 {
     const VALUE: *const bindings::PropertyInfo = unsafe { &bindings::qdev_prop_uint64 };
 }
 
-/// Use [`bindings::qdev_prop_chr`] for [`crate::chardev::CharBackend`].
-unsafe impl QDevProp for crate::chardev::CharBackend {
+/// Use [`bindings::qdev_prop_chr`] for [`chardev::CharBackend`].
+unsafe impl QDevProp for chardev::CharBackend {
     const VALUE: *const bindings::PropertyInfo = unsafe { &bindings::qdev_prop_chr };
 }
 

rust/qemu-api/wrapper.h

@@ -52,13 +52,11 @@ typedef enum memory_order {
 #include "system/system.h"
 #include "hw/sysbus.h"
 #include "system/memory.h"
-#include "chardev/char-fe.h"
 #include "hw/clock.h"
 #include "hw/qdev-clock.h"
 #include "hw/qdev-properties.h"
 #include "hw/qdev-properties-system.h"
 #include "hw/irq.h"
-#include "chardev/char-serial.h"
 #include "exec/memattrs.h"
 #include "system/address-spaces.h"
 #include "hw/char/pl011.h"