vmm: interrupt: create GSI hashmap directly

The observation is that the GSI hashmap remains untouched before getting
passed into the MSI interrupt manager. We can create that hashmap
directly in the interrupt manager's new function.

The drops one import from the interrupt module.

Signed-off-by: Wei Liu <liuwe@microsoft.com>

vmm/src/interrupt.rs

@@ -103,7 +103,7 @@ impl InterruptRoute {
     }
 }
 
-pub struct KvmRoutingEntry {
+struct KvmRoutingEntry {
     kvm_route: kvm_irq_routing_entry,
     masked: bool,
 }
@@ -327,11 +327,13 @@ impl KvmLegacyUserspaceInterruptManager {
 }
 
 impl KvmMsiInterruptManager {
-    pub fn new(
-        allocator: Arc<Mutex<SystemAllocator>>,
-        vm_fd: Arc<dyn hypervisor::Vm>,
-        gsi_msi_routes: Arc<Mutex<HashMap<u32, KvmRoutingEntry>>>,
-    ) -> Self {
+    pub fn new(allocator: Arc<Mutex<SystemAllocator>>, vm_fd: Arc<dyn hypervisor::Vm>) -> Self {
+        // Create a shared list of GSI that can be shared through all PCI
+        // devices. This way, we can maintain the full list of used GSI,
+        // preventing one device from overriding interrupts setting from
+        // another one.
+        let gsi_msi_routes = Arc::new(Mutex::new(HashMap::new()));
+
         KvmMsiInterruptManager {
             allocator,
             vm_fd,