pci: Detect BAR reprogramming

Based on the value being written to the BAR, the implementation can
now detect if the BAR is being moved to another address. If that is the
case, it invokes move_bar() function from the DeviceRelocation trait.

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

pci/src/device.rs

@@ -47,6 +47,14 @@ impl Display for Error {
     }
 }
 
+#[derive(Clone, Copy)]
+pub struct BarReprogrammingParams {
+    pub old_base: u64,
+    pub new_base: u64,
+    pub len: u64,
+    pub region_type: PciBarRegionType,
+}
+
 pub trait PciDevice: BusDevice {
     /// Assign a legacy PCI IRQ to this device.
     /// The device may write to `irq_evt` to trigger an interrupt.
@@ -82,6 +90,14 @@ pub trait PciDevice: BusDevice {
     /// Gets a register from the configuration space.
     /// * `reg_idx` - The index of the config register to read.
     fn read_config_register(&self, reg_idx: usize) -> u32;
+    /// Detects if a BAR is being reprogrammed.
+    fn detect_bar_reprogramming(
+        &mut self,
+        _reg_idx: usize,
+        _data: &[u8],
+    ) -> Option<BarReprogrammingParams> {
+        None
+    }
     /// Reads from a BAR region mapped in to the device.
     /// * `addr` - The guest address inside the BAR.
     /// * `data` - Filled with the data from `addr`.