src/irqchip/whpx.rs

// Copyright 2021 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use std::convert::TryFrom;
use std::sync::Arc;

use anyhow::Context;
use serde::Deserialize;
use serde::Serialize;
use sync::Mutex;

cfg_if::cfg_if! {
    if #[cfg(test)] {
        use base::FakeClock as Clock;
    } else {
        use base::Clock;
    }
}
use base::error;
use base::Error;
use base::Event;
use base::Result;
use base::Tube;
use hypervisor::whpx::WhpxVcpu;
use hypervisor::whpx::WhpxVm;
use hypervisor::IoapicState;
use hypervisor::IrqRoute;
use hypervisor::IrqSource;
use hypervisor::IrqSourceChip;
use hypervisor::LapicState;
use hypervisor::MPState;
use hypervisor::MsiAddressMessage;
use hypervisor::MsiDataMessage;
use hypervisor::PicSelect;
use hypervisor::PicState;
use hypervisor::PitState;
use hypervisor::Vcpu;
use hypervisor::VcpuX86_64;
use hypervisor::Vm;
use resources::SystemAllocator;

use crate::irqchip::DelayedIoApicIrqEvents;
use crate::irqchip::InterruptData;
use crate::irqchip::InterruptDestination;
use crate::irqchip::Ioapic;
use crate::irqchip::IrqEvent;
use crate::irqchip::IrqEventIndex;
use crate::irqchip::Pic;
use crate::irqchip::Routes;
use crate::irqchip::VcpuRunState;
use crate::irqchip::IOAPIC_BASE_ADDRESS;
use crate::irqchip::IOAPIC_MEM_LENGTH_BYTES;
use crate::Bus;
use crate::IrqChip;
use crate::IrqChipCap;
use crate::IrqChipX86_64;
use crate::IrqEdgeEvent;
use crate::IrqEventSource;
use crate::IrqLevelEvent;
use crate::Pit;
use crate::PitError;

/// PIT channel 0 timer is connected to IRQ 0
const PIT_CHANNEL0_IRQ: u32 = 0;
/// TODO(b/187464379): we don't know what the right frequency is here, but 100MHz gives
/// us better results than the frequency that WSL seems to use, which is 500MHz.
const WHPX_LOCAL_APIC_EMULATION_APIC_FREQUENCY: u32 = 100_000_000;

/// The WhpxSplitIrqChip supports
pub struct WhpxSplitIrqChip {
    vm: WhpxVm,
    routes: Arc<Mutex<Routes>>,
    pit: Arc<Mutex<Pit>>,
    pic: Arc<Mutex<Pic>>,
    ioapic: Arc<Mutex<Ioapic>>,
    ioapic_pins: usize,
    /// Delayed ioapic irq object, that contains the delayed events because the ioapic was locked
    /// when service_irq was called on the irqchip. This prevents deadlocks when a Vcpu thread has
    /// locked the ioapic and the ioapic sends a AddMsiRoute signal to the main thread (which
    /// itself may be busy trying to call service_irq).
    ///
    /// ## Note:
    /// This lock may be locked by itself to access the `DelayedIoApicIrqEvents`. If accessed in
    /// conjunction with the `irq_events` field, that lock should be taken first to prevent
    /// deadlocks stemming from lock-ordering issues.
    delayed_ioapic_irq_events: Arc<Mutex<DelayedIoApicIrqEvents>>,
    /// Array of Events that devices will use to assert ioapic pins.
    irq_events: Arc<Mutex<Vec<Option<IrqEvent>>>>,
}

impl WhpxSplitIrqChip {
    /// Construct a new WhpxSplitIrqChip.
    pub fn new(vm: WhpxVm, irq_tube: Tube, ioapic_pins: Option<usize>) -> Result<Self> {
        let pit_evt = IrqEdgeEvent::new()?;
        let pit = Pit::new(pit_evt.try_clone()?, Arc::new(Mutex::new(Clock::new()))).map_err(
            |e| match e {
                PitError::CloneEvent(err) => err,
                PitError::CreateEvent(err) => err,
                PitError::CreateWaitContext(err) => err,
                PitError::WaitError(err) => err,
                PitError::TimerCreateError(err) => err,
                PitError::SpawnThread(_) => Error::new(libc::EIO),
            },
        )?;

        let pit_event_source = IrqEventSource::from_device(&pit);

        let ioapic_pins = ioapic_pins.unwrap_or(hypervisor::NUM_IOAPIC_PINS);
        let ioapic = Ioapic::new(irq_tube, ioapic_pins)?;

        let mut chip = WhpxSplitIrqChip {
            vm,
            routes: Arc::new(Mutex::new(Routes::new())),
            pit: Arc::new(Mutex::new(pit)),
            pic: Arc::new(Mutex::new(Pic::new())),
            ioapic: Arc::new(Mutex::new(ioapic)),
            ioapic_pins,
            delayed_ioapic_irq_events: Arc::new(Mutex::new(DelayedIoApicIrqEvents::new()?)),
            irq_events: Arc::new(Mutex::new(Vec::new())),
        };

        // This is equivalent to setting this in the blank Routes object above because
        // WhpxSplitIrqChip doesn't interact with the WHPX API when setting routes, but in case
        // that changes we do it this way.
        chip.set_irq_routes(&Routes::default_pic_ioapic_routes(ioapic_pins))?;

        // Add the pit
        chip.register_edge_irq_event(PIT_CHANNEL0_IRQ, &pit_evt, pit_event_source)?;
        Ok(chip)
    }

    /// Sends a Message Signaled Interrupt to one or more APICs. The WHPX API does not accept the
    /// MSI address and data directly, so we must parse them and supply WHPX with the vector,
    /// destination id, destination mode, trigger mode, and delivery mode (aka interrupt type).
    fn send_msi(&self, addr: u32, data: u32) -> Result<()> {
        let mut msi_addr = MsiAddressMessage::new();
        msi_addr.set(0, 32, addr as u64);
        let dest = InterruptDestination::try_from(&msi_addr).or(Err(Error::new(libc::EINVAL)))?;

        let mut msi_data = MsiDataMessage::new();
        msi_data.set(0, 32, data as u64);
        let data = InterruptData::from(&msi_data);

        self.vm.request_interrupt(
            data.vector,
            dest.dest_id,
            dest.mode,
            data.trigger,
            data.delivery,
        )
    }

    /// Return true if there is a pending interrupt for the specified vcpu. For WhpxSplitIrqChip
    /// this calls interrupt_requested on the pic.
    pub fn interrupt_requested(&self, vcpu_id: usize) -> bool {
        // Pic interrupts for the split irqchip only go to vcpu 0
        if vcpu_id != 0 {
            return false;
        }
        self.pic.lock().interrupt_requested()
    }

    /// Check if the specified vcpu has any pending interrupts. Returns [`None`] for no interrupts,
    /// otherwise [`Some::<u8>`] should be the injected interrupt vector. For [`WhpxSplitIrqChip`]
    /// this calls `get_external_interrupt` on the pic.
    pub fn get_external_interrupt(&self, vcpu_id: usize) -> Result<Option<u8>> {
        // Pic interrupts for the split irqchip only go to vcpu 0
        if vcpu_id != 0 {
            return Ok(None);
        }
        if let Some(vector) = self.pic.lock().get_external_interrupt() {
            Ok(Some(vector))
        } else {
            Ok(None)
        }
    }
}

impl WhpxSplitIrqChip {
    fn register_irq_event(
        &mut self,
        irq: u32,
        irq_event: &Event,
        resample_event: Option<&Event>,
        source: IrqEventSource,
    ) -> Result<Option<usize>> {
        let mut evt = IrqEvent {
            gsi: irq,
            event: irq_event.try_clone()?,
            resample_event: None,
            source,
        };

        if let Some(resample_event) = resample_event {
            evt.resample_event = Some(resample_event.try_clone()?);
        }

        let mut irq_events = self.irq_events.lock();
        let index = irq_events.len();
        irq_events.push(Some(evt));
        Ok(Some(index))
    }

    fn unregister_irq_event(&mut self, irq: u32, irq_event: &Event) -> Result<()> {
        let mut irq_events = self.irq_events.lock();
        for (index, evt) in irq_events.iter().enumerate() {
            if let Some(evt) = evt {
                if evt.gsi == irq && irq_event.eq(&evt.event) {
                    irq_events[index] = None;
                    break;
                }
            }
        }
        Ok(())
    }
}

/// This IrqChip only works with Whpx so we only implement it for WhpxVcpu.
impl IrqChip for WhpxSplitIrqChip {
    fn add_vcpu(&mut self, _vcpu_id: usize, _vcpu: &dyn Vcpu) -> Result<()> {
        // The WHPX API acts entirely on the VM partition, so we don't need to keep references to
        // the vcpus.
        Ok(())
    }

    fn register_edge_irq_event(
        &mut self,
        irq: u32,
        irq_event: &IrqEdgeEvent,
        source: IrqEventSource,
    ) -> Result<Option<IrqEventIndex>> {
        self.register_irq_event(irq, irq_event.get_trigger(), None, source)
    }

    fn unregister_edge_irq_event(&mut self, irq: u32, irq_event: &IrqEdgeEvent) -> Result<()> {
        self.unregister_irq_event(irq, irq_event.get_trigger())
    }

    fn register_level_irq_event(
        &mut self,
        irq: u32,
        irq_event: &IrqLevelEvent,
        source: IrqEventSource,
    ) -> Result<Option<IrqEventIndex>> {
        self.register_irq_event(
            irq,
            irq_event.get_trigger(),
            Some(irq_event.get_resample()),
            source,
        )
    }

    fn unregister_level_irq_event(&mut self, irq: u32, irq_event: &IrqLevelEvent) -> Result<()> {
        self.unregister_irq_event(irq, irq_event.get_trigger())
    }

    fn route_irq(&mut self, route: IrqRoute) -> Result<()> {
        self.routes.lock().add(route)
    }

    fn set_irq_routes(&mut self, routes: &[IrqRoute]) -> Result<()> {
        self.routes.lock().replace_all(routes)
    }

    fn irq_event_tokens(&self) -> Result<Vec<(IrqEventIndex, IrqEventSource, Event)>> {
        let mut tokens: Vec<(IrqEventIndex, IrqEventSource, Event)> = Vec::new();
        for (index, evt) in self.irq_events.lock().iter().enumerate() {
            if let Some(evt) = evt {
                tokens.push((index, evt.source.clone(), evt.event.try_clone()?));
            }
        }
        Ok(tokens)
    }

    fn service_irq(&mut self, irq: u32, level: bool) -> Result<()> {
        for route in self.routes.lock()[irq as usize].iter() {
            match *route {
                IrqSource::Irqchip {
                    chip: IrqSourceChip::PicPrimary,
                    pin,
                }
                | IrqSource::Irqchip {
                    chip: IrqSourceChip::PicSecondary,
                    pin,
                } => {
                    self.pic.lock().service_irq(pin as u8, level);
                }
                IrqSource::Irqchip {
                    chip: IrqSourceChip::Ioapic,
                    pin,
                } => {
                    self.ioapic.lock().service_irq(pin as usize, level);
                }
                // service_irq's level parameter is ignored for MSIs.  MSI data specifies the level.
                IrqSource::Msi { address, data } => self.send_msi(address as u32, data)?,
                _ => {
                    error!("Unexpected route source {:?}", route);
                    return Err(Error::new(libc::EINVAL));
                }
            }
        }
        Ok(())
    }

    /// Services an IRQ event by asserting then deasserting an IRQ line.  The associated Event
    /// that triggered the irq event will be read from.  If the irq is associated with a resample
    /// Event, then the deassert will only happen after an EOI is broadcast for a vector
    /// associated with the irq line.
    /// For WhpxSplitIrqChip, this function identifies the destination(s) of the irq: PIC, IOAPIC,
    /// or APIC (MSI).  If it's a PIC or IOAPIC route, we attempt to call service_irq on those
    /// chips.  If the IOAPIC is unable to be immediately locked, we add the irq to the
    /// delayed_ioapic_irq_events (though we still read from the Event that triggered the irq
    /// event).  If it's an MSI route, we call send_msi to decode the MSI and send the interrupt
    /// to WHPX.
    fn service_irq_event(&mut self, event_index: IrqEventIndex) -> Result<()> {
        let irq_events = self.irq_events.lock();
        let evt = if let Some(evt) = &irq_events[event_index] {
            evt
        } else {
            return Ok(());
        };
        evt.event.wait()?;

        for route in self.routes.lock()[evt.gsi as usize].iter() {
            match *route {
                IrqSource::Irqchip {
                    chip: IrqSourceChip::PicPrimary,
                    pin,
                }
                | IrqSource::Irqchip {
                    chip: IrqSourceChip::PicSecondary,
                    pin,
                } => {
                    let mut pic = self.pic.lock();
                    if evt.resample_event.is_some() {
                        pic.service_irq(pin as u8, true);
                    } else {
                        pic.service_irq(pin as u8, true);
                        pic.service_irq(pin as u8, false);
                    }
                }
                IrqSource::Irqchip {
                    chip: IrqSourceChip::Ioapic,
                    pin,
                } => {
                    if let Ok(mut ioapic) = self.ioapic.try_lock() {
                        if evt.resample_event.is_some() {
                            ioapic.service_irq(pin as usize, true);
                        } else {
                            ioapic.service_irq(pin as usize, true);
                            ioapic.service_irq(pin as usize, false);
                        }
                    } else {
                        let mut delayed_events = self.delayed_ioapic_irq_events.lock();
                        delayed_events.events.push(event_index);
                        delayed_events.trigger.signal()?;
                    }
                }
                IrqSource::Msi { address, data } => self.send_msi(address as u32, data)?,
                _ => {
                    error!("Unexpected route source {:?}", route);
                    return Err(Error::new(libc::EINVAL));
                }
            }
        }

        Ok(())
    }

    /// Broadcasts an end of interrupt. For WhpxSplitIrqChip this sends the EOI to the Ioapic.
    fn broadcast_eoi(&self, vector: u8) -> Result<()> {
        self.ioapic.lock().end_of_interrupt(vector);
        Ok(())
    }

    /// Injects any pending interrupts for `vcpu`.
    /// For WhpxSplitIrqChip this injects any PIC interrupts on vcpu_id 0.
    fn inject_interrupts(&self, vcpu: &dyn Vcpu) -> Result<()> {
        let vcpu: &WhpxVcpu = vcpu
            .downcast_ref()
            .expect("WhpxSplitIrqChip::add_vcpu called with non-WhpxVcpu");
        let vcpu_id = vcpu.id();
        if !self.interrupt_requested(vcpu_id) || !vcpu.ready_for_interrupt() {
            return Ok(());
        }

        if let Some(vector) = self.get_external_interrupt(vcpu_id)? {
            vcpu.interrupt(vector)?;
        }

        // The second interrupt request should be handled immediately, so ask vCPU to exit as soon
        // as possible.
        if self.interrupt_requested(vcpu_id) {
            vcpu.set_interrupt_window_requested(true);
        }
        Ok(())
    }

    /// Notifies the irq chip that the specified VCPU has executed a halt instruction.
    /// For WhpxSplitIrqChip this is a no-op because Whpx handles VCPU blocking.
    fn halted(&self, _vcpu_id: usize) {}

    /// Blocks until `vcpu` is in a runnable state or until interrupted by
    /// `IrqChip::kick_halted_vcpus`.  Returns `VcpuRunState::Runnable if vcpu is runnable, or
    /// `VcpuRunState::Interrupted` if the wait was interrupted.
    /// For WhpxSplitIrqChip this is a no-op and always returns Runnable because Whpx handles VCPU
    /// blocking.
    fn wait_until_runnable(&self, _vcpu: &dyn Vcpu) -> Result<VcpuRunState> {
        Ok(VcpuRunState::Runnable)
    }

    /// Makes unrunnable VCPUs return immediately from `wait_until_runnable`.
    /// For WhpxSplitIrqChip this is a no-op because Whpx handles VCPU blocking.
    fn kick_halted_vcpus(&self) {}

    fn get_mp_state(&self, _vcpu_id: usize) -> Result<MPState> {
        // WHPX does not seem to have an API for this, but luckily this API isn't used anywhere
        // except the plugin.
        Err(Error::new(libc::ENXIO))
    }

    fn set_mp_state(&mut self, _vcpu_id: usize, _state: &MPState) -> Result<()> {
        // WHPX does not seem to have an API for this, but luckily this API isn't used anywhere
        // except the plugin.
        Err(Error::new(libc::ENXIO))
    }

    fn try_clone(&self) -> Result<Self>
    where
        Self: Sized,
    {
        Ok(WhpxSplitIrqChip {
            vm: self.vm.try_clone()?,
            routes: self.routes.clone(),
            pit: self.pit.clone(),
            pic: self.pic.clone(),
            ioapic: self.ioapic.clone(),
            ioapic_pins: self.ioapic_pins,
            delayed_ioapic_irq_events: self.delayed_ioapic_irq_events.clone(),
            irq_events: self.irq_events.clone(),
        })
    }

    fn finalize_devices(
        &mut self,
        resources: &mut SystemAllocator,
        io_bus: &Bus,
        mmio_bus: &Bus,
    ) -> Result<()> {
        // Insert pit into io_bus
        io_bus.insert(self.pit.clone(), 0x040, 0x8).unwrap();
        io_bus.insert(self.pit.clone(), 0x061, 0x1).unwrap();

        // Insert pic into io_bus
        io_bus.insert(self.pic.clone(), 0x20, 0x2).unwrap();
        io_bus.insert(self.pic.clone(), 0xa0, 0x2).unwrap();
        io_bus.insert(self.pic.clone(), 0x4d0, 0x2).unwrap();

        // Insert ioapic into mmio_bus
        mmio_bus
            .insert(
                self.ioapic.clone(),
                IOAPIC_BASE_ADDRESS,
                IOAPIC_MEM_LENGTH_BYTES,
            )
            .unwrap();

        // At this point, all of our devices have been created and they have registered their
        // irq events, so we can clone our resample events
        let mut ioapic_resample_events: Vec<Vec<Event>> =
            (0..self.ioapic_pins).map(|_| Vec::new()).collect();
        let mut pic_resample_events: Vec<Vec<Event>> =
            (0..self.ioapic_pins).map(|_| Vec::new()).collect();

        for evt in self.irq_events.lock().iter().flatten() {
            if (evt.gsi as usize) >= self.ioapic_pins {
                continue;
            }
            if let Some(resample_evt) = &evt.resample_event {
                ioapic_resample_events[evt.gsi as usize].push(resample_evt.try_clone()?);
                pic_resample_events[evt.gsi as usize].push(resample_evt.try_clone()?);
            }
        }

        // Register resample events with the ioapic
        self.ioapic
            .lock()
            .register_resample_events(ioapic_resample_events);
        // Register resample events with the pic
        self.pic
            .lock()
            .register_resample_events(pic_resample_events);

        // Make sure all future irq numbers are >= self.ioapic_pins
        let mut irq_num = resources.allocate_irq().unwrap();
        while irq_num < self.ioapic_pins as u32 {
            irq_num = resources.allocate_irq().unwrap();
        }

        Ok(())
    }

    fn process_delayed_irq_events(&mut self) -> Result<()> {
        let irq_events = self.irq_events.lock();
        let mut delayed_events = self.delayed_ioapic_irq_events.lock();
        delayed_events.events.retain(|&event_index| {
            if let Some(evt) = &irq_events[event_index] {
                if let Ok(mut ioapic) = self.ioapic.try_lock() {
                    if evt.resample_event.is_some() {
                        ioapic.service_irq(evt.gsi as usize, true);
                    } else {
                        ioapic.service_irq(evt.gsi as usize, true);
                        ioapic.service_irq(evt.gsi as usize, false);
                    }

                    false
                } else {
                    true
                }
            } else {
                true
            }
        });

        if delayed_events.events.is_empty() {
            delayed_events.trigger.wait()?;
        }
        Ok(())
    }

    fn irq_delayed_event_token(&self) -> Result<Option<Event>> {
        Ok(Some(
            self.delayed_ioapic_irq_events.lock().trigger.try_clone()?,
        ))
    }

    fn check_capability(&self, c: IrqChipCap) -> bool {
        match c {
            // It appears as though WHPX does not have tsc deadline support because we get guest
            // MSR write failures if we enable it.
            IrqChipCap::TscDeadlineTimer => false,
            // TODO(b/180966070): Figure out how to query x2apic support.
            IrqChipCap::X2Apic => false,
            IrqChipCap::MpStateGetSet => false,
        }
    }
}

#[derive(Serialize, Deserialize)]
struct WhpxSplitIrqChipSnapshot {
    routes: Vec<IrqRoute>,
}

impl IrqChipX86_64 for WhpxSplitIrqChip {
    fn try_box_clone(&self) -> Result<Box<dyn IrqChipX86_64>> {
        Ok(Box::new(self.try_clone()?))
    }

    fn as_irq_chip(&self) -> &dyn IrqChip {
        self
    }

    fn as_irq_chip_mut(&mut self) -> &mut dyn IrqChip {
        self
    }

    /// Get the current state of the PIC
    fn get_pic_state(&self, select: PicSelect) -> Result<PicState> {
        Ok(self.pic.lock().get_pic_state(select))
    }

    /// Set the current state of the PIC
    fn set_pic_state(&mut self, select: PicSelect, state: &PicState) -> Result<()> {
        self.pic.lock().set_pic_state(select, state);
        Ok(())
    }

    /// Get the current state of the IOAPIC
    fn get_ioapic_state(&self) -> Result<IoapicState> {
        Ok(self.ioapic.lock().get_ioapic_state())
    }

    /// Set the current state of the IOAPIC
    fn set_ioapic_state(&mut self, state: &IoapicState) -> Result<()> {
        self.ioapic.lock().set_ioapic_state(state);
        Ok(())
    }

    /// Get the current state of the specified VCPU's local APIC
    fn get_lapic_state(&self, vcpu_id: usize) -> Result<LapicState> {
        self.vm.get_vcpu_lapic_state(vcpu_id)
    }

    /// Set the current state of the specified VCPU's local APIC
    fn set_lapic_state(&mut self, vcpu_id: usize, state: &LapicState) -> Result<()> {
        self.vm.set_vcpu_lapic_state(vcpu_id, state)
    }

    fn lapic_frequency(&self) -> u32 {
        WHPX_LOCAL_APIC_EMULATION_APIC_FREQUENCY
    }

    /// Retrieves the state of the PIT.
    fn get_pit(&self) -> Result<PitState> {
        Ok(self.pit.lock().get_pit_state())
    }

    /// Sets the state of the PIT.
    fn set_pit(&mut self, state: &PitState) -> Result<()> {
        self.pit.lock().set_pit_state(state);
        Ok(())
    }

    /// Returns true if the PIT uses port 0x61 for the PC speaker, false if 0x61 is unused.
    /// devices::Pit uses 0x61.
    fn pit_uses_speaker_port(&self) -> bool {
        true
    }

    fn snapshot_chip_specific(&self) -> anyhow::Result<serde_json::Value> {
        serde_json::to_value(&WhpxSplitIrqChipSnapshot {
            routes: self.routes.lock().get_routes(),
        })
        .context("failed to snapshot WhpxSplitIrqChip")
    }

    fn restore_chip_specific(&mut self, data: serde_json::Value) -> anyhow::Result<()> {
        let mut deser: WhpxSplitIrqChipSnapshot =
            serde_json::from_value(data).context("failed to deserialize WhpxSplitIrqChip")?;
        self.set_irq_routes(deser.routes.as_slice())?;
        Ok(())
    }
}