diff options
author | Stefan Hajnoczi <stefanha@redhat.com> | 2025-06-21 10:00:46 -0400 |
---|---|---|
committer | Stefan Hajnoczi <stefanha@redhat.com> | 2025-06-21 10:00:46 -0400 |
commit | 43ba160cb4bbb193560eb0d2d7decc4b5fc599fe (patch) | |
tree | 2a12561d9da7a4bee1ad5279fe8dd10f4432d74a /rust | |
parent | 6e1571533fd92bec67e5ab9b1dd1e15032925757 (diff) | |
parent | 40da501d8989913935660dc24953ece02c9e98b8 (diff) | |
download | qemu-master.zip qemu-master.tar.gz qemu-master.tar.bz2 |
* cleanups for distributed DTB files
* scripts/meson-buildoptions: Sort coroutine_backend choices lexicographically
* rust/qemu-api: Add initial logging support
: rust: pl011: Implement logging
* target/i386: fix Win98
* meson: cleanup win32 library detection
* rust: safe(r) instance_init
* rust: prepare for multiple bindgen invocations
* rust: fix new warning
* target/i386: Warn about why CPUID_EXT_PDCM is not available
* target/i386: small TDX fixes and clarifications
* target/i386: support for TDX quote generation
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# -----END PGP SIGNATURE-----
# gpg: Signature made Fri 20 Jun 2025 07:26:35 EDT
# gpg: using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg: issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
# Subkey fingerprint: F133 3857 4B66 2389 866C 7682 BFFB D25F 78C7 AE83
* tag 'for-upstream' of https://gitlab.com/bonzini/qemu: (24 commits)
i386/tdx: handle TDG.VP.VMCALL<GetQuote>
i386/tdx: handle TDG.VP.VMCALL<GetTdVmCallInfo>
update Linux headers to v6.16-rc3
i386/tdx: Clarify the error message of mrconfigid/mrowner/mrownerconfig
i386/tdx: Fix the typo of the comment of struct TdxGuest
i386/cpu: Rename enable_cpuid_0x1f to force_cpuid_0x1f
i386/tdx: Error and exit when named cpu model is requested
i386/cpu: Warn about why CPUID_EXT_PDCM is not available
i386/cpu: Move adjustment of CPUID_EXT_PDCM before feature_dependencies[] check
rust: hpet: fix new warning
rust: pl011: Add missing logging to match C version
rust: pl011: Implement logging
rust/qemu-api: Add initial logging support based on C API
rust: move rust.bindgen to qemu-api crate
rust: prepare variable definitions for multiple bindgen invocations
rust: qom: change instance_init to take a ParentInit<>
rust: qom: make ParentInit lifetime-invariant
rust: qom: introduce ParentInit
rust: hpet: fully initialize object during instance_init
rust: qemu_api: introduce MaybeUninit field projection
...
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'rust')
-rw-r--r-- | rust/hw/char/pl011/src/device.rs | 52 | ||||
-rw-r--r-- | rust/hw/timer/hpet/src/device.rs | 58 | ||||
-rw-r--r-- | rust/meson.build | 4 | ||||
-rw-r--r-- | rust/qemu-api/build.rs | 2 | ||||
-rw-r--r-- | rust/qemu-api/meson.build | 45 | ||||
-rw-r--r-- | rust/qemu-api/src/lib.rs | 2 | ||||
-rw-r--r-- | rust/qemu-api/src/log.rs | 73 | ||||
-rw-r--r-- | rust/qemu-api/src/memory.rs | 12 | ||||
-rw-r--r-- | rust/qemu-api/src/prelude.rs | 2 | ||||
-rw-r--r-- | rust/qemu-api/src/qdev.rs | 49 | ||||
-rw-r--r-- | rust/qemu-api/src/qom.rs | 186 | ||||
-rw-r--r-- | rust/qemu-api/src/uninit.rs | 85 | ||||
-rw-r--r-- | rust/qemu-api/wrapper.h (renamed from rust/wrapper.h) | 2 |
13 files changed, 490 insertions, 82 deletions
diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs index be8387f..5b53f26 100644 --- a/rust/hw/char/pl011/src/device.rs +++ b/rust/hw/char/pl011/src/device.rs @@ -2,18 +2,21 @@ // Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org> // SPDX-License-Identifier: GPL-2.0-or-later -use std::{ffi::CStr, mem::size_of, ptr::addr_of_mut}; +use std::{ffi::CStr, mem::size_of}; use qemu_api::{ chardev::{CharBackend, Chardev, Event}, impl_vmstate_forward, irq::{IRQState, InterruptSource}, + log::Log, + log_mask_ln, memory::{hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder}, prelude::*, qdev::{Clock, ClockEvent, DeviceImpl, DeviceState, Property, ResetType, ResettablePhasesImpl}, - qom::{ObjectImpl, Owned, ParentField}, + qom::{ObjectImpl, Owned, ParentField, ParentInit}, static_assert, sysbus::{SysBusDevice, SysBusDeviceImpl}, + uninit_field_mut, vmstate::VMStateDescription, }; @@ -163,7 +166,7 @@ impl PL011Impl for PL011State { impl ObjectImpl for PL011State { type ParentType = SysBusDevice; - const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = Some(Self::init); + const INSTANCE_INIT: Option<unsafe fn(ParentInit<Self>)> = Some(Self::init); const INSTANCE_POST_INIT: Option<fn(&Self)> = Some(Self::post_init); const CLASS_INIT: fn(&mut Self::Class) = Self::Class::class_init::<Self>; } @@ -275,8 +278,7 @@ impl PL011Registers { DMACR => { self.dmacr = value; if value & 3 > 0 { - // qemu_log_mask(LOG_UNIMP, "pl011: DMA not implemented\n"); - eprintln!("pl011: DMA not implemented"); + log_mask_ln!(Log::Unimp, "pl011: DMA not implemented"); } } } @@ -303,6 +305,12 @@ impl PL011Registers { } fn write_data_register(&mut self, value: u32) -> bool { + if !self.control.enable_uart() { + log_mask_ln!(Log::GuestError, "PL011 data written to disabled UART"); + } + if !self.control.enable_transmit() { + log_mask_ln!(Log::GuestError, "PL011 data written to disabled TX UART"); + } // interrupts always checked let _ = self.loopback_tx(value.into()); self.int_level |= Interrupt::TX; @@ -488,7 +496,7 @@ impl PL011State { /// `PL011State` type. It must not be called more than once on the same /// location/instance. All its fields are expected to hold uninitialized /// values with the sole exception of `parent_obj`. - unsafe fn init(&mut self) { + unsafe fn init(mut this: ParentInit<Self>) { static PL011_OPS: MemoryRegionOps<PL011State> = MemoryRegionOpsBuilder::<PL011State>::new() .read(&PL011State::read) .write(&PL011State::write) @@ -496,28 +504,23 @@ impl PL011State { .impl_sizes(4, 4) .build(); - // SAFETY: - // - // self and self.iomem are guaranteed to be valid at this point since callers - // must make sure the `self` reference is valid. + // SAFETY: this and this.iomem are guaranteed to be valid at this point MemoryRegion::init_io( - unsafe { &mut *addr_of_mut!(self.iomem) }, - addr_of_mut!(*self), + &mut uninit_field_mut!(*this, iomem), &PL011_OPS, "pl011", 0x1000, ); - self.regs = Default::default(); + uninit_field_mut!(*this, regs).write(Default::default()); - // SAFETY: - // - // self.clock is not initialized at this point; but since `Owned<_>` is - // not Drop, we can overwrite the undefined value without side effects; - // it's not sound but, because for all PL011State instances are created - // by QOM code which calls this function to initialize the fields, at - // leastno code is able to access an invalid self.clock value. - self.clock = self.init_clock_in("clk", &Self::clock_update, ClockEvent::ClockUpdate); + let clock = DeviceState::init_clock_in( + &mut this, + "clk", + &Self::clock_update, + ClockEvent::ClockUpdate, + ); + uninit_field_mut!(*this, clock).write(clock); } const fn clock_update(&self, _event: ClockEvent) { @@ -538,7 +541,7 @@ impl PL011State { u64::from(device_id[(offset - 0xfe0) >> 2]) } Err(_) => { - // qemu_log_mask(LOG_GUEST_ERROR, "pl011_read: Bad offset 0x%x\n", (int)offset); + log_mask_ln!(Log::GuestError, "PL011State::read: Bad offset {offset}"); 0 } Ok(field) => { @@ -570,7 +573,10 @@ impl PL011State { .borrow_mut() .write(field, value as u32, &self.char_backend); } else { - eprintln!("write bad offset {offset} value {value}"); + log_mask_ln!( + Log::GuestError, + "PL011State::write: Bad offset {offset} value {value}" + ); } if update_irq { self.update(); diff --git a/rust/hw/timer/hpet/src/device.rs b/rust/hw/timer/hpet/src/device.rs index 735b2fb..acf7251 100644 --- a/rust/hw/timer/hpet/src/device.rs +++ b/rust/hw/timer/hpet/src/device.rs @@ -4,6 +4,7 @@ use std::{ ffi::{c_int, c_void, CStr}, + mem::MaybeUninit, pin::Pin, ptr::{addr_of_mut, null_mut, NonNull}, slice::from_ref, @@ -20,11 +21,12 @@ use qemu_api::{ hwaddr, MemoryRegion, MemoryRegionOps, MemoryRegionOpsBuilder, MEMTXATTRS_UNSPECIFIED, }, prelude::*, - qdev::{DeviceImpl, DeviceMethods, DeviceState, Property, ResetType, ResettablePhasesImpl}, - qom::{ObjectImpl, ObjectType, ParentField}, + qdev::{DeviceImpl, DeviceState, Property, ResetType, ResettablePhasesImpl}, + qom::{ObjectImpl, ObjectType, ParentField, ParentInit}, qom_isa, sysbus::{SysBusDevice, SysBusDeviceImpl}, timer::{Timer, CLOCK_VIRTUAL, NANOSECONDS_PER_SECOND}, + uninit_field_mut, vmstate::VMStateDescription, vmstate_fields, vmstate_of, vmstate_struct, vmstate_subsections, vmstate_validate, zeroable::Zeroable, @@ -212,13 +214,13 @@ pub struct HPETTimer { } impl HPETTimer { - fn init(&mut self, index: u8, state: &HPETState) { - *self = HPETTimer { + fn new(index: u8, state: *const HPETState) -> HPETTimer { + HPETTimer { index, // SAFETY: the HPETTimer will only be used after the timer // is initialized below. qemu_timer: unsafe { Timer::new() }, - state: NonNull::new((state as *const HPETState).cast_mut()).unwrap(), + state: NonNull::new(state.cast_mut()).unwrap(), config: 0, cmp: 0, fsb: 0, @@ -226,19 +228,15 @@ impl HPETTimer { period: 0, wrap_flag: 0, last: 0, - }; + } + } + fn init_timer_with_cell(cell: &BqlRefCell<Self>) { + let mut timer = cell.borrow_mut(); // SAFETY: HPETTimer is only used as part of HPETState, which is // always pinned. - let qemu_timer = unsafe { Pin::new_unchecked(&mut self.qemu_timer) }; - qemu_timer.init_full( - None, - CLOCK_VIRTUAL, - Timer::NS, - 0, - timer_handler, - &state.timers[self.index as usize], - ) + let qemu_timer = unsafe { Pin::new_unchecked(&mut timer.qemu_timer) }; + qemu_timer.init_full(None, CLOCK_VIRTUAL, Timer::NS, 0, timer_handler, cell); } fn get_state(&self) -> &HPETState { @@ -607,9 +605,18 @@ impl HPETState { } } - fn init_timer(&self) { - for (index, timer) in self.timers.iter().enumerate() { - timer.borrow_mut().init(index.try_into().unwrap(), self); + fn init_timers(this: &mut MaybeUninit<Self>) { + let state = this.as_ptr(); + for index in 0..HPET_MAX_TIMERS { + let mut timer = uninit_field_mut!(*this, timers[index]); + + // Initialize in two steps, to avoid calling Timer::init_full on a + // temporary that can be moved. + let timer = timer.write(BqlRefCell::new(HPETTimer::new( + index.try_into().unwrap(), + state, + ))); + HPETTimer::init_timer_with_cell(timer); } } @@ -690,7 +697,7 @@ impl HPETState { .set(self.counter.get().deposit(shift, len, val)); } - unsafe fn init(&mut self) { + unsafe fn init(mut this: ParentInit<Self>) { static HPET_RAM_OPS: MemoryRegionOps<HPETState> = MemoryRegionOpsBuilder::<HPETState>::new() .read(&HPETState::read) @@ -700,16 +707,14 @@ impl HPETState { .impl_sizes(4, 8) .build(); - // SAFETY: - // self and self.iomem are guaranteed to be valid at this point since callers - // must make sure the `self` reference is valid. MemoryRegion::init_io( - unsafe { &mut *addr_of_mut!(self.iomem) }, - addr_of_mut!(*self), + &mut uninit_field_mut!(*this, iomem), &HPET_RAM_OPS, "hpet", HPET_REG_SPACE_LEN, ); + + Self::init_timers(&mut this); } fn post_init(&self) { @@ -731,7 +736,6 @@ impl HPETState { self.hpet_id.set(HPETFwConfig::assign_hpet_id()?); - self.init_timer(); // 64-bit General Capabilities and ID Register; LegacyReplacementRoute. self.capability.set( HPET_CAP_REV_ID_VALUE << HPET_CAP_REV_ID_SHIFT | @@ -767,7 +771,7 @@ impl HPETState { self.rtc_irq_level.set(0); } - fn decode(&self, mut addr: hwaddr, size: u32) -> HPETAddrDecode { + fn decode(&self, mut addr: hwaddr, size: u32) -> HPETAddrDecode<'_> { let shift = ((addr & 4) * 8) as u32; let len = std::cmp::min(size * 8, 64 - shift); @@ -892,7 +896,7 @@ unsafe impl ObjectType for HPETState { impl ObjectImpl for HPETState { type ParentType = SysBusDevice; - const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = Some(Self::init); + const INSTANCE_INIT: Option<unsafe fn(ParentInit<Self>)> = Some(Self::init); const INSTANCE_POST_INIT: Option<fn(&Self)> = Some(Self::post_init); const CLASS_INIT: fn(&mut Self::Class) = Self::Class::class_init::<Self>; } diff --git a/rust/meson.build b/rust/meson.build index 99ae795..331f11b 100644 --- a/rust/meson.build +++ b/rust/meson.build @@ -20,6 +20,8 @@ proc_macro2_rs_native = dependency('proc-macro2-1-rs', native: true) qemuutil_rs = qemuutil.partial_dependency(link_args: true, links: true) +genrs = [] + subdir('qemu-api-macros') subdir('bits') subdir('qemu-api') @@ -33,5 +35,5 @@ if cargo.found() command: [config_host['MESON'], 'devenv', '--workdir', '@CURRENT_SOURCE_DIR@', cargo, 'fmt'], - depends: bindings_rs) + depends: genrs) endif diff --git a/rust/qemu-api/build.rs b/rust/qemu-api/build.rs index 1e72064..7849486 100644 --- a/rust/qemu-api/build.rs +++ b/rust/qemu-api/build.rs @@ -14,7 +14,7 @@ fn main() -> Result<()> { let path = env::var("MESON_BUILD_ROOT") .unwrap_or_else(|_| format!("{}/src", env!("CARGO_MANIFEST_DIR"))); - let file = format!("{path}/bindings.inc.rs"); + let file = format!("{path}/rust/qemu-api/bindings.inc.rs"); let file = Path::new(&file); if !Path::new(&file).exists() { panic!(concat!( diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build index cac8595..a090297 100644 --- a/rust/qemu-api/meson.build +++ b/rust/qemu-api/meson.build @@ -7,6 +7,47 @@ if get_option('debug_mutex') _qemu_api_cfg += ['--cfg', 'feature="debug_cell"'] endif +c_enums = [ + 'DeviceCategory', + 'GpioPolarity', + 'MachineInitPhase', + 'MemoryDeviceInfoKind', + 'MigrationPolicy', + 'MigrationPriority', + 'QEMUChrEvent', + 'QEMUClockType', + 'ResetType', + 'device_endian', + 'module_init_type', +] +_qemu_api_bindgen_args = [] +foreach enum : c_enums + _qemu_api_bindgen_args += ['--rustified-enum', enum] +endforeach +c_bitfields = [ + 'ClockEvent', + 'VMStateFlags', +] +foreach enum : c_bitfields + _qemu_api_bindgen_args += ['--bitfield-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 +_qemu_api_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 + _qemu_api_bindgen_args, + ) + _qemu_api_rs = static_library( 'qemu_api', structured_sources( @@ -21,6 +62,7 @@ _qemu_api_rs = static_library( 'src/errno.rs', 'src/error.rs', 'src/irq.rs', + 'src/log.rs', 'src/memory.rs', 'src/module.rs', 'src/prelude.rs', @@ -28,10 +70,11 @@ _qemu_api_rs = static_library( 'src/qom.rs', 'src/sysbus.rs', 'src/timer.rs', + 'src/uninit.rs', 'src/vmstate.rs', 'src/zeroable.rs', ], - {'.' : bindings_rs}, + {'.' : _qemu_api_bindings_inc_rs}, ), override_options: ['rust_std=2021', 'build.rust_std=2021'], rust_abi: 'rust', diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs index 93902fc..86dcd8e 100644 --- a/rust/qemu-api/src/lib.rs +++ b/rust/qemu-api/src/lib.rs @@ -21,12 +21,14 @@ pub mod chardev; pub mod errno; pub mod error; pub mod irq; +pub mod log; pub mod memory; pub mod module; pub mod qdev; pub mod qom; pub mod sysbus; pub mod timer; +pub mod uninit; pub mod vmstate; pub mod zeroable; diff --git a/rust/qemu-api/src/log.rs b/rust/qemu-api/src/log.rs new file mode 100644 index 0000000..d6c3d6c --- /dev/null +++ b/rust/qemu-api/src/log.rs @@ -0,0 +1,73 @@ +// Copyright 2025 Bernhard Beschow <shentey@gmail.com> +// SPDX-License-Identifier: GPL-2.0-or-later + +//! Bindings for QEMU's logging infrastructure + +#[repr(u32)] +/// Represents specific error categories within QEMU's logging system. +/// +/// The `Log` enum provides a Rust abstraction for logging errors, corresponding +/// to a subset of the error categories defined in the C implementation. +pub enum Log { + /// Log invalid access caused by the guest. + /// Corresponds to `LOG_GUEST_ERROR` in the C implementation. + GuestError = crate::bindings::LOG_GUEST_ERROR, + + /// Log guest access of unimplemented functionality. + /// Corresponds to `LOG_UNIMP` in the C implementation. + Unimp = crate::bindings::LOG_UNIMP, +} + +/// A macro to log messages conditionally based on a provided mask. +/// +/// The `log_mask_ln` macro checks whether the given mask matches the current +/// log level and, if so, formats and logs the message. It is the Rust +/// counterpart of the `qemu_log_mask()` macro in the C implementation. +/// +/// # Parameters +/// +/// - `$mask`: A log level mask. This should be a variant of the `Log` enum. +/// - `$fmt`: A format string following the syntax and rules of the `format!` +/// macro. It specifies the structure of the log message. +/// - `$args`: Optional arguments to be interpolated into the format string. +/// +/// # Example +/// +/// ``` +/// use qemu_api::{log::Log, log_mask_ln}; +/// +/// let error_address = 0xbad; +/// log_mask_ln!(Log::GuestError, "Address 0x{error_address:x} out of range"); +/// ``` +/// +/// It is also possible to use printf-style formatting, as well as having a +/// trailing `,`: +/// +/// ``` +/// use qemu_api::{log::Log, log_mask_ln}; +/// +/// let error_address = 0xbad; +/// log_mask_ln!( +/// Log::GuestError, +/// "Address 0x{:x} out of range", +/// error_address, +/// ); +/// ``` +#[macro_export] +macro_rules! log_mask_ln { + ($mask:expr, $fmt:tt $($args:tt)*) => {{ + // Type assertion to enforce type `Log` for $mask + let _: Log = $mask; + + if unsafe { + (::qemu_api::bindings::qemu_loglevel & ($mask as std::os::raw::c_int)) != 0 + } { + let formatted_string = format!("{}\n", format_args!($fmt $($args)*)); + let c_string = std::ffi::CString::new(formatted_string).unwrap(); + + unsafe { + ::qemu_api::bindings::qemu_log(c_string.as_ptr()); + } + } + }}; +} diff --git a/rust/qemu-api/src/memory.rs b/rust/qemu-api/src/memory.rs index 9ef2694..e40fad6 100644 --- a/rust/qemu-api/src/memory.rs +++ b/rust/qemu-api/src/memory.rs @@ -16,6 +16,7 @@ use crate::{ callbacks::FnCall, cell::Opaque, prelude::*, + uninit::MaybeUninitField, zeroable::Zeroable, }; @@ -147,7 +148,7 @@ impl MemoryRegion { #[inline(always)] unsafe fn do_init_io( slot: *mut bindings::MemoryRegion, - owner: *mut Object, + owner: *mut bindings::Object, ops: &'static bindings::MemoryRegionOps, name: &'static str, size: u64, @@ -156,7 +157,7 @@ impl MemoryRegion { let cstr = CString::new(name).unwrap(); memory_region_init_io( slot, - owner.cast::<bindings::Object>(), + owner, ops, owner.cast::<c_void>(), cstr.as_ptr(), @@ -166,16 +167,15 @@ impl MemoryRegion { } pub fn init_io<T: IsA<Object>>( - &mut self, - owner: *mut T, + this: &mut MaybeUninitField<'_, T, Self>, ops: &'static MemoryRegionOps<T>, name: &'static str, size: u64, ) { unsafe { Self::do_init_io( - self.0.as_mut_ptr(), - owner.cast::<Object>(), + this.as_mut_ptr().cast(), + MaybeUninitField::parent_mut(this).cast(), &ops.0, name, size, diff --git a/rust/qemu-api/src/prelude.rs b/rust/qemu-api/src/prelude.rs index 43bfcd5..8f9e23e 100644 --- a/rust/qemu-api/src/prelude.rs +++ b/rust/qemu-api/src/prelude.rs @@ -11,6 +11,8 @@ pub use crate::cell::BqlRefCell; pub use crate::errno; +pub use crate::log_mask_ln; + pub use crate::qdev::DeviceMethods; pub use crate::qom::InterfaceType; diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index 0610959..36f02fb 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -19,7 +19,7 @@ use crate::{ error::{Error, Result}, irq::InterruptSource, prelude::*, - qom::{ObjectClass, ObjectImpl, Owned}, + qom::{ObjectClass, ObjectImpl, Owned, ParentInit}, vmstate::VMStateDescription, }; @@ -247,15 +247,9 @@ unsafe impl ObjectType for DeviceState { } qom_isa!(DeviceState: Object); -/// Trait for methods exposed by the [`DeviceState`] class. The methods can be -/// called on all objects that have the trait `IsA<DeviceState>`. -/// -/// The trait should only be used through the blanket implementation, -/// which guarantees safety via `IsA`. -pub trait DeviceMethods: ObjectDeref -where - Self::Target: IsA<DeviceState>, -{ +/// Initialization methods take a [`ParentInit`] and can be called as +/// associated functions. +impl DeviceState { /// Add an input clock named `name`. Invoke the callback with /// `self` as the first parameter for the events that are requested. /// @@ -266,12 +260,15 @@ where /// which Rust code has a reference to a child object) it would be /// possible for this function to return a `&Clock` too. #[inline] - fn init_clock_in<F: for<'a> FnCall<(&'a Self::Target, ClockEvent)>>( - &self, + pub fn init_clock_in<T: DeviceImpl, F: for<'a> FnCall<(&'a T, ClockEvent)>>( + this: &mut ParentInit<T>, name: &str, _cb: &F, events: ClockEvent, - ) -> Owned<Clock> { + ) -> Owned<Clock> + where + T::ParentType: IsA<DeviceState>, + { fn do_init_clock_in( dev: &DeviceState, name: &str, @@ -287,10 +284,10 @@ where unsafe { let cstr = CString::new(name).unwrap(); let clk = bindings::qdev_init_clock_in( - dev.as_mut_ptr(), + dev.0.as_mut_ptr(), cstr.as_ptr(), cb, - dev.as_void_ptr(), + dev.0.as_void_ptr(), events.0, ); @@ -307,12 +304,12 @@ where // SAFETY: the opaque is "this", which is indeed a pointer to T F::call((unsafe { &*(opaque.cast::<T>()) }, event)) } - Some(rust_clock_cb::<Self::Target, F>) + Some(rust_clock_cb::<T, F>) } else { None }; - do_init_clock_in(self.upcast(), name, cb, events) + do_init_clock_in(unsafe { this.upcast_mut() }, name, cb, events) } /// Add an output clock named `name`. @@ -324,16 +321,30 @@ where /// which Rust code has a reference to a child object) it would be /// possible for this function to return a `&Clock` too. #[inline] - fn init_clock_out(&self, name: &str) -> Owned<Clock> { + pub fn init_clock_out<T: DeviceImpl>(this: &mut ParentInit<T>, name: &str) -> Owned<Clock> + where + T::ParentType: IsA<DeviceState>, + { unsafe { let cstr = CString::new(name).unwrap(); - let clk = bindings::qdev_init_clock_out(self.upcast().as_mut_ptr(), cstr.as_ptr()); + let dev: &mut DeviceState = this.upcast_mut(); + let clk = bindings::qdev_init_clock_out(dev.0.as_mut_ptr(), cstr.as_ptr()); let clk: &Clock = Clock::from_raw(clk); Owned::from(clk) } } +} +/// Trait for methods exposed by the [`DeviceState`] class. The methods can be +/// called on all objects that have the trait `IsA<DeviceState>`. +/// +/// The trait should only be used through the blanket implementation, +/// which guarantees safety via `IsA`. +pub trait DeviceMethods: ObjectDeref +where + Self::Target: IsA<DeviceState>, +{ fn prop_set_chr(&self, propname: &str, chr: &Owned<Chardev>) { assert!(bql_locked()); let c_propname = CString::new(propname).unwrap(); diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs index 14f98fe..e20ee01 100644 --- a/rust/qemu-api/src/qom.rs +++ b/rust/qemu-api/src/qom.rs @@ -95,7 +95,8 @@ use std::{ ffi::{c_void, CStr}, fmt, - mem::ManuallyDrop, + marker::PhantomData, + mem::{ManuallyDrop, MaybeUninit}, ops::{Deref, DerefMut}, ptr::NonNull, }; @@ -206,13 +207,190 @@ impl<T: fmt::Display + ObjectType> fmt::Display for ParentField<T> { } } +/// This struct knows that the superclasses of the object have already been +/// initialized. +/// +/// The declaration of `ParentInit` is.. *"a kind of magic"*. It uses a +/// technique that is found in several crates, the main ones probably being +/// `ghost-cell` (in fact it was introduced by the [`GhostCell` paper](https://plv.mpi-sws.org/rustbelt/ghostcell/)) +/// and `generativity`. +/// +/// The `PhantomData` makes the `ParentInit` type *invariant* with respect to +/// the lifetime argument `'init`. This, together with the `for<'...>` in +/// `[ParentInit::with]`, block any attempt of the compiler to be creative when +/// operating on types of type `ParentInit` and to extend their lifetimes. In +/// particular, it ensures that the `ParentInit` cannot be made to outlive the +/// `rust_instance_init()` function that creates it, and therefore that the +/// `&'init T` reference is valid. +/// +/// This implementation of the same concept, without the QOM baggage, can help +/// understanding the effect: +/// +/// ``` +/// use std::marker::PhantomData; +/// +/// #[derive(PartialEq, Eq)] +/// pub struct Jail<'closure, T: Copy>(&'closure T, PhantomData<fn(&'closure ()) -> &'closure ()>); +/// +/// impl<'closure, T: Copy> Jail<'closure, T> { +/// fn get(&self) -> T { +/// *self.0 +/// } +/// +/// #[inline] +/// fn with<U>(v: T, f: impl for<'id> FnOnce(Jail<'id, T>) -> U) -> U { +/// let parent_init = Jail(&v, PhantomData); +/// f(parent_init) +/// } +/// } +/// ``` +/// +/// It's impossible to escape the `Jail`; `token1` cannot be moved out of the +/// closure: +/// +/// ```ignore +/// let x = 42; +/// let escape = Jail::with(&x, |token1| { +/// println!("{}", token1.get()); +/// // fails to compile... +/// token1 +/// }); +/// // ... so you cannot do this: +/// println!("{}", escape.get()); +/// ``` +/// +/// Likewise, in the QOM case the `ParentInit` cannot be moved out of +/// `instance_init()`. Without this trick it would be possible to stash a +/// `ParentInit` and use it later to access uninitialized memory. +/// +/// Here is another example, showing how separately-created "identities" stay +/// isolated: +/// +/// ```ignore +/// impl<'closure, T: Copy> Clone for Jail<'closure, T> { +/// fn clone(&self) -> Jail<'closure, T> { +/// Jail(self.0, PhantomData) +/// } +/// } +/// +/// fn main() { +/// Jail::with(42, |token1| { +/// // this works and returns true: the clone has the same "identity" +/// println!("{}", token1 == token1.clone()); +/// Jail::with(42, |token2| { +/// // here the outer token remains accessible... +/// println!("{}", token1.get()); +/// // ... but the two are separate: this fails to compile: +/// println!("{}", token1 == token2); +/// }); +/// }); +/// } +/// ``` +pub struct ParentInit<'init, T>( + &'init mut MaybeUninit<T>, + PhantomData<fn(&'init ()) -> &'init ()>, +); + +impl<'init, T> ParentInit<'init, T> { + #[inline] + pub fn with(obj: &'init mut MaybeUninit<T>, f: impl for<'id> FnOnce(ParentInit<'id, T>)) { + let parent_init = ParentInit(obj, PhantomData); + f(parent_init) + } +} + +impl<T: ObjectType> ParentInit<'_, T> { + /// Return the receiver as a mutable raw pointer to Object. + /// + /// # Safety + /// + /// Fields beyond `Object` could be uninitialized and it's your + /// responsibility to avoid that they're used when the pointer is + /// dereferenced, either directly or through a cast. + pub fn as_object_mut_ptr(&self) -> *mut bindings::Object { + self.as_object_ptr().cast_mut() + } + + /// Return the receiver as a mutable raw pointer to Object. + /// + /// # Safety + /// + /// Fields beyond `Object` could be uninitialized and it's your + /// responsibility to avoid that they're used when the pointer is + /// dereferenced, either directly or through a cast. + pub fn as_object_ptr(&self) -> *const bindings::Object { + self.0.as_ptr().cast() + } +} + +impl<'a, T: ObjectImpl> ParentInit<'a, T> { + /// Convert from a derived type to one of its parent types, which + /// have already been initialized. + /// + /// # Safety + /// + /// Structurally this is always a safe operation; the [`IsA`] trait + /// provides static verification trait that `Self` dereferences to `U` or + /// a child of `U`, and only parent types of `T` are allowed. + /// + /// However, while the fields of the resulting reference are initialized, + /// calls might use uninitialized fields of the subclass. It is your + /// responsibility to avoid this. + pub unsafe fn upcast<U: ObjectType>(&self) -> &'a U + where + T::ParentType: IsA<U>, + { + // SAFETY: soundness is declared via IsA<U>, which is an unsafe trait; + // the parent has been initialized before `instance_init `is called + unsafe { &*(self.0.as_ptr().cast::<U>()) } + } + + /// Convert from a derived type to one of its parent types, which + /// have already been initialized. + /// + /// # Safety + /// + /// Structurally this is always a safe operation; the [`IsA`] trait + /// provides static verification trait that `Self` dereferences to `U` or + /// a child of `U`, and only parent types of `T` are allowed. + /// + /// However, while the fields of the resulting reference are initialized, + /// calls might use uninitialized fields of the subclass. It is your + /// responsibility to avoid this. + pub unsafe fn upcast_mut<U: ObjectType>(&mut self) -> &'a mut U + where + T::ParentType: IsA<U>, + { + // SAFETY: soundness is declared via IsA<U>, which is an unsafe trait; + // the parent has been initialized before `instance_init `is called + unsafe { &mut *(self.0.as_mut_ptr().cast::<U>()) } + } +} + +impl<T> Deref for ParentInit<'_, T> { + type Target = MaybeUninit<T>; + + fn deref(&self) -> &Self::Target { + self.0 + } +} + +impl<T> DerefMut for ParentInit<'_, T> { + fn deref_mut(&mut self) -> &mut Self::Target { + self.0 + } +} + unsafe extern "C" fn rust_instance_init<T: ObjectImpl>(obj: *mut bindings::Object) { - let mut state = NonNull::new(obj).unwrap().cast::<T>(); + let mut state = NonNull::new(obj).unwrap().cast::<MaybeUninit<T>>(); + // SAFETY: obj is an instance of T, since rust_instance_init<T> // is called from QOM core as the instance_init function // for class T unsafe { - T::INSTANCE_INIT.unwrap()(state.as_mut()); + ParentInit::with(state.as_mut(), |parent_init| { + T::INSTANCE_INIT.unwrap()(parent_init); + }); } } @@ -479,7 +657,7 @@ pub trait ObjectImpl: ObjectType + IsA<Object> { /// /// FIXME: The argument is not really a valid reference. `&mut /// MaybeUninit<Self>` would be a better description. - const INSTANCE_INIT: Option<unsafe fn(&mut Self)> = None; + const INSTANCE_INIT: Option<unsafe fn(ParentInit<Self>)> = None; /// Function that is called to finish initialization of an object, once /// `INSTANCE_INIT` functions have been called. diff --git a/rust/qemu-api/src/uninit.rs b/rust/qemu-api/src/uninit.rs new file mode 100644 index 0000000..04123b4 --- /dev/null +++ b/rust/qemu-api/src/uninit.rs @@ -0,0 +1,85 @@ +//! Access fields of a [`MaybeUninit`] + +use std::{ + mem::MaybeUninit, + ops::{Deref, DerefMut}, +}; + +pub struct MaybeUninitField<'a, T, U> { + parent: &'a mut MaybeUninit<T>, + child: *mut U, +} + +impl<'a, T, U> MaybeUninitField<'a, T, U> { + #[doc(hidden)] + pub fn new(parent: &'a mut MaybeUninit<T>, child: *mut U) -> Self { + MaybeUninitField { parent, child } + } + + /// Return a constant pointer to the containing object of the field. + /// + /// Because the `MaybeUninitField` remembers the containing object, + /// it is possible to use it in foreign APIs that initialize the + /// child. + pub fn parent(f: &Self) -> *const T { + f.parent.as_ptr() + } + + /// Return a mutable pointer to the containing object. + /// + /// Because the `MaybeUninitField` remembers the containing object, + /// it is possible to use it in foreign APIs that initialize the + /// child. + pub fn parent_mut(f: &mut Self) -> *mut T { + f.parent.as_mut_ptr() + } +} + +impl<'a, T, U> Deref for MaybeUninitField<'a, T, U> { + type Target = MaybeUninit<U>; + + fn deref(&self) -> &MaybeUninit<U> { + // SAFETY: self.child was obtained by dereferencing a valid mutable + // reference; the content of the memory may be invalid or uninitialized + // but MaybeUninit<_> makes no assumption on it + unsafe { &*(self.child.cast()) } + } +} + +impl<'a, T, U> DerefMut for MaybeUninitField<'a, T, U> { + fn deref_mut(&mut self) -> &mut MaybeUninit<U> { + // SAFETY: self.child was obtained by dereferencing a valid mutable + // reference; the content of the memory may be invalid or uninitialized + // but MaybeUninit<_> makes no assumption on it + unsafe { &mut *(self.child.cast()) } + } +} + +/// ``` +/// #[derive(Debug)] +/// struct S { +/// x: u32, +/// y: u32, +/// } +/// +/// # use std::mem::MaybeUninit; +/// # use qemu_api::{assert_match, uninit_field_mut}; +/// +/// let mut s: MaybeUninit<S> = MaybeUninit::zeroed(); +/// uninit_field_mut!(s, x).write(5); +/// let s = unsafe { s.assume_init() }; +/// assert_match!(s, S { x: 5, y: 0 }); +/// ``` +#[macro_export] +macro_rules! uninit_field_mut { + ($container:expr, $($field:tt)+) => {{ + let container__: &mut ::std::mem::MaybeUninit<_> = &mut $container; + let container_ptr__ = container__.as_mut_ptr(); + + // SAFETY: the container is not used directly, only through a MaybeUninit<>, + // so the safety is delegated to the caller and to final invocation of + // assume_init() + let target__ = unsafe { std::ptr::addr_of_mut!((*container_ptr__).$($field)+) }; + $crate::uninit::MaybeUninitField::new(container__, target__) + }}; +} diff --git a/rust/wrapper.h b/rust/qemu-api/wrapper.h index 6060d3b..15a1b19 100644 --- a/rust/wrapper.h +++ b/rust/qemu-api/wrapper.h @@ -48,6 +48,8 @@ typedef enum memory_order { #endif /* __CLANG_STDATOMIC_H */ #include "qemu/osdep.h" +#include "qemu/log.h" +#include "qemu/log-for-trace.h" #include "qemu/module.h" #include "qemu-io.h" #include "system/system.h" |