devices: vmm: Add ACPI PM timer

This is a counter exposed via an I/O port that runs at 3.579545MHz. Here
we use a hardcoded I/O and expose the details through the FADT table.

TEST=Boot Linux kernel and see the following in dmesg:

[    0.506198] clocksource: acpi_pm: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

devices/src/acpi.rs

@@ -5,6 +5,7 @@
 
 use acpi_tables::{aml, aml::Aml};
 use std::sync::Arc;
+use std::time::Instant;
 use vm_device::interrupt::InterruptSourceGroup;
 use vmm_sys_util::eventfd::EventFd;
 use BusDevice;
@@ -149,3 +150,39 @@ impl Aml for AcpiGEDDevice {
         .to_aml_bytes()
     }
 }
+
+pub struct AcpiPMTimerDevice {
+    start: Instant,
+}
+
+impl AcpiPMTimerDevice {
+    pub fn new() -> Self {
+        Self {
+            start: Instant::now(),
+        }
+    }
+}
+
+impl Default for AcpiPMTimerDevice {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl BusDevice for AcpiPMTimerDevice {
+    fn read(&mut self, _base: u64, _offset: u64, data: &mut [u8]) {
+        let now = Instant::now();
+        let since = now.duration_since(self.start);
+        let nanos = since.as_nanos();
+
+        const PM_TIMER_FREQUENCY_HZ: u128 = 3_579_545;
+        const NANOS_PER_SECOND: u128 = 1_000_000_000;
+
+        let counter = (nanos * PM_TIMER_FREQUENCY_HZ) / NANOS_PER_SECOND;
+        let counter: u32 = (counter & 0xffff_ffff) as u32;
+
+        data.copy_from_slice(&counter.to_le_bytes());
+    }
+
+    fn write(&mut self, _base: u64, _offset: u64, _data: &[u8]) {}
+}

devices/src/lib.rs

@@ -39,7 +39,7 @@ pub mod ioapic;
 pub mod legacy;
 
 #[cfg(feature = "acpi")]
-pub use self::acpi::{AcpiGEDDevice, AcpiShutdownDevice};
+pub use self::acpi::{AcpiGEDDevice, AcpiPMTimerDevice, AcpiShutdownDevice};
 pub use self::bus::{Bus, BusDevice, Error as BusError};
 
 pub type DeviceEventT = u16;

vmm/src/acpi.rs

@@ -64,8 +64,11 @@ pub fn create_acpi_tables(
     // Revision 6 of the ACPI FADT table is 276 bytes long
     let mut facp = SDT::new(*b"FACP", 276, 6, *b"CLOUDH", *b"CHFACP  ", 1);
 
-    // HW_REDUCED_ACPI and RESET_REG_SUP
-    let fadt_flags: u32 = 1 << 20 | 1 << 10;
+    // PM_TMR_BLK I/O port
+    facp.write(76, 0xb008);
+
+    // HW_REDUCED_ACPI, RESET_REG_SUP, TMR_VAL_EXT
+    let fadt_flags: u32 = 1 << 20 | 1 << 10 | 1 << 8;
     facp.write(112, fadt_flags);
 
     // RESET_REG
@@ -76,6 +79,9 @@ pub fn create_acpi_tables(
     facp.write(131, 3u8); // FADT minor version
     facp.write(140, dsdt_offset.0); // X_DSDT
 
+    // X_PM_TMR_BLK
+    facp.write(208, GenericAddress::io_port_address(0xb008));
+
     // SLEEP_CONTROL_REG
     facp.write(244, GenericAddress::io_port_address(0x3c0));
     // SLEEP_STATUS_REG

vmm/src/device_manager.rs

@@ -1224,6 +1224,24 @@ impl DeviceManager {
             .io_bus
             .insert(ged_device.clone(), 0xb000, 0x1)
             .map_err(DeviceManagerError::BusError)?;
+
+        let pm_timer_device = Arc::new(Mutex::new(devices::AcpiPMTimerDevice::new()));
+
+        self.bus_devices
+            .push(Arc::clone(&pm_timer_device) as Arc<Mutex<dyn BusDevice>>);
+
+        self.address_manager
+            .allocator
+            .lock()
+            .unwrap()
+            .allocate_io_addresses(Some(GuestAddress(0xb008)), 0x4, None)
+            .ok_or(DeviceManagerError::AllocateIOPort)?;
+
+        self.address_manager
+            .io_bus
+            .insert(pm_timer_device, 0xb008, 0x4)
+            .map_err(DeviceManagerError::BusError)?;
+
         Ok(Some(ged_device))
     }