vmm: api: Introduce new "remove-device" HTTP endpoint

This commit introduces the new command "remove-device" that will let a
user hot-unplug a VFIO PCI device from an already running VM.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/device_manager.rs

@@ -236,6 +236,10 @@ pub enum DeviceManagerError {
 
     /// Failed removing a bus device from the MMIO bus.
     RemoveDeviceFromMmioBus(devices::BusError),
+
+    /// Failed to find VFIO device corresponding to the given identifier.
+    #[cfg(feature = "pci_support")]
+    UnknownVfioDeviceId(String),
 }
 pub type DeviceManagerResult<T> = result::Result<T, DeviceManagerError>;
 
@@ -1791,6 +1795,18 @@ impl DeviceManager {
         Ok(device_cfg)
     }
 
+    #[cfg(feature = "pci_support")]
+    pub fn remove_device(&mut self, id: String) -> DeviceManagerResult<()> {
+        if let Some(pci_device_bdf) = self.pci_id_list.get(&id) {
+            // Update the PCID bitmap
+            self.pci_devices_down |= 1 << (*pci_device_bdf >> 3);
+
+            Ok(())
+        } else {
+            Err(DeviceManagerError::UnknownVfioDeviceId(id))
+        }
+    }
+
     #[cfg(feature = "pci_support")]
     pub fn eject_device(&mut self, device_id: u8) -> DeviceManagerResult<()> {
         // Retrieve the PCI bus.