pci: Extend the Device trait to carry the device BARs

When reading from or writing to a PCI BAR to handle a VM exit, we need
to have the BAR address itself to be able to support multiple BARs PCI
devices.

Fixes: #87

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

pci/src/device.rs

@@ -90,11 +90,11 @@ pub trait PciDevice: BusDevice {
     /// Reads from a BAR region mapped in to the device.
     /// * `addr` - The guest address inside the BAR.
     /// * `data` - Filled with the data from `addr`.
-    fn read_bar(&mut self, addr: u64, data: &mut [u8]);
+    fn read_bar(&mut self, base: u64, offset: u64, data: &mut [u8]);
     /// Writes to a BAR region mapped in to the device.
     /// * `addr` - The guest address inside the BAR.
     /// * `data` - The data to write.
-    fn write_bar(&mut self, addr: u64, data: &[u8]);
+    fn write_bar(&mut self, base: u64, offset: u64, data: &[u8]);
     /// Invoked when the device is sandboxed.
     fn on_device_sandboxed(&mut self) {}
 }