vmm: Ensure uniqueness of generated identifiers

The device identifiers generated from the DeviceManager were not
guaranteed to be unique since they were not taking the list of
identifiers provided through the configuration.

By returning the list of unique identifiers from the configuration, and
by providing it to the DeviceManager, the generation of new identifiers
can rely both on the DeviceTree and the list of IDs from the
configuration.

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

vmm/src/config.rs

@@ -2329,7 +2329,9 @@ pub struct VmConfig {
 
 impl VmConfig {
     // Also enables virtio-iommu if the config needs it
-    pub fn validate(&mut self) -> ValidationResult<()> {
+    // Returns the list of unique identifiers provided through the
+    // configuration.
+    pub fn validate(&mut self) -> ValidationResult<BTreeSet<String>> {
         let mut id_list = BTreeSet::new();
 
         #[cfg(not(feature = "tdx"))]
@@ -2578,7 +2580,7 @@ impl VmConfig {
             .map(|p| p.iommu_segments.is_some())
             .unwrap_or_default();
 
-        Ok(())
+        Ok(id_list)
     }
 
     pub fn parse(vm_params: VmParams) -> Result<Self> {