Add IO manager support

Based on resources definition, this adds device IO manager to manage
all devices IO ranges.

Signed-off-by: Jing Liu <[email protected]>

Author: Jing Liu

src/device_manager.rs

@@ -0,0 +1,105 @@
+// Copyright © 2019 Intel Corporation. All Rights Reserved.
+// SPDX-License-Identifier: (Apache-2.0 AND BSD-3-Clause)
+
+//! System level device management.
+//!
+//! [IoManager](struct.IoManager.html) responds to manage all devices
+//! of virtual machine, register IO resources callback,
+//! unregister devices and help VM IO exit handling.
+//！
+//！VMM would take responsible for getting device resource request, ask
+//! vm_allocator to allocate the resources, ask vm_device to register the
+//! devices IO windows, and finally set resources to virtual device.
+
+use crate::resources::Resource;
+use crate::DeviceIo;
+
+use std::collections::btree_map::BTreeMap;
+use std::result;
+use std::sync::Arc;
+
+/// Error type for `IoManager` usage.
+#[derive(Debug)]
+pub enum Error {
+    /// The inserting device overlaps with a current device.
+    DeviceOverlap,
+}
+
+/// Simplify the `Result` type.
+pub type Result<T> = result::Result<T, Error>;
+
+/// System IO manager serving for all devices management and VM exit handling.
+#[derive(Default)]
+pub struct IoManager {
+    /// Range mapping for VM exit pio operations.
+    pio_bus: BTreeMap<(u16, u16), Arc<dyn DeviceIo>>,
+    /// Range mapping for VM exit mmio operations.
+    mmio_bus: BTreeMap<(u64, u64), Arc<dyn DeviceIo>>,
+}
+
+impl IoManager {
+    pub fn new() -> Self {
+        IoManager::default()
+    }
+    /// Register a new device IO with its allocated resources.
+    /// VMM is responsible for providing the allocated resources to virtual device.
+    ///
+    /// # Arguements
+    ///
+    /// * `device`: device instance object to be registered
+    /// * `resources`: resources that this device owns, might include
+    ///                port I/O and memory-mapped I/O ranges, irq number, etc.
+    pub fn register_device_io(
+        &mut self,
+        device: Arc<dyn DeviceIo>,
+        resources: &[Resource],
+    ) -> Result<()> {
+        // Register and mark device resources
+        // The resources addresses being registered are sucessfully allocated before.
+        for (idx, res) in resources.iter().enumerate() {
+            match *res {
+                Resource::PioAddressRange { base, size } => {
+                    if self.pio_bus.insert((base, size), device.clone()).is_some() {
+                        // Unregister registered resources.
+                        self.unregister_device_io(&resources[0..idx])?;
+
+                        return Err(Error::DeviceOverlap);
+                    }
+                }
+                Resource::MmioAddressRange { base, size } => {
+                    if self.mmio_bus.insert((base, size), device.clone()).is_some() {
+                        // Unregister registered resources.
+                        self.unregister_device_io(&resources[0..idx])?;
+
+                        return Err(Error::DeviceOverlap);
+                    }
+                }
+                _ => continue,
+            }
+        }
+        Ok(())
+    }
+
+    /// Unregister a device from `IoManager`, e.g. users specified removing.
+    /// VMM pre-fetches the resources e.g. dev.get_assigned_resources()
+    /// VMM is responsible for freeing the resources.
+    ///
+    /// # Arguements
+    ///
+    /// * `resources`: resources that this device owns, might include
+    ///                port I/O and memory-mapped I/O ranges, irq number, etc.
+    pub fn unregister_device_io(&mut self, resources: &[Resource]) -> Result<()> {
+        for res in resources.iter() {
+            match *res {
+                Resource::PioAddressRange { base, size } => {
+                    self.pio_bus.remove(&(base, size));
+                }
+                Resource::MmioAddressRange { base, size } => {
+                    self.mmio_bus.remove(&(base, size));
+                }
+                _ => continue,
+            }
+        }
+        Ok(())
+    }
+}

src/lib.rs

@@ -7,6 +7,7 @@ extern crate vm_memory;
 
 use vm_memory::GuestAddress;
 
+pub mod device_manager;
 pub mod resources;
 
 /// IO Addresses.