vmm: Introduce PciDeviceCommonConfig::validate()

Implement some common PCI segment validation. This can be used to reduce
duplication across the different validation methods.

Signed-off-by: Rob Bradford <rbradford@meta.com>

vmm/src/config.rs

@@ -1226,6 +1226,23 @@ impl PciDeviceCommonConfig {
             pci_segment,
         })
     }
+
+    pub fn validate(&self, vm_config: &VmConfig) -> ValidationResult<()> {
+        if let Some(platform_config) = vm_config.platform.as_ref() {
+            if self.pci_segment >= platform_config.num_pci_segments {
+                return Err(ValidationError::InvalidPciSegment(self.pci_segment));
+            }
+
+            if let Some(iommu_segments) = platform_config.iommu_segments.as_ref()
+                && iommu_segments.contains(&self.pci_segment)
+                && !self.iommu
+            {
+                return Err(ValidationError::OnIommuSegment(self.pci_segment));
+            }
+        }
+
+        Ok(())
+    }
 }
 
 impl DiskConfig {