vmm: config: Switch UserDeviceConfig to use PciDeviceCommonConfig

Switch UserDeviceConfig over to using the newly extracted struct members
as used by all PCI based devices. The use of #[serde(flatten)] means
that this change has no impact on the JSON format that the data is
stored as.

As VFIO user devices do not support being placed behind an IOMMU an
error is now raised if iommu is set. This can't happen via the CLI but
could via the JSON/API.

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

vmm/src/config.rs

@@ -2244,39 +2244,21 @@ impl UserDeviceConfig {
         parser.add("socket").add("id").add("pci_segment");
         parser.parse(user_device).map_err(Error::ParseUserDevice)?;
 
+        let pci_common = PciDeviceCommonConfig::parse(user_device)?;
         let socket = parser
             .get("socket")
             .map(PathBuf::from)
             .ok_or(Error::ParseUserDeviceSocketMissing)?;
-        let id = parser.get("id");
-        let pci_segment = parser
-            .convert::<u16>("pci_segment")
-            .map_err(Error::ParseUserDevice)?
-            .unwrap_or_default();
 
-        Ok(UserDeviceConfig {
-            socket,
-            id,
-            pci_segment,
-        })
+        Ok(UserDeviceConfig { pci_common, socket })
     }
 
     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)
-            {
-                return Err(ValidationError::IommuNotSupportedOnSegment(
-                    self.pci_segment,
-                ));
-            }
+        if self.pci_common.iommu {
+            return Err(ValidationError::IommuNotSupported);
         }
 
-        Ok(())
+        self.pci_common.validate(vm_config)
     }
 }
 
@@ -3052,7 +3034,7 @@ impl VmConfig {
             for user_device in user_devices {
                 user_device.validate(self)?;
 
-                Self::validate_identifier(&mut id_list, &user_device.id)?;
+                Self::validate_identifier(&mut id_list, &user_device.pci_common.id)?;
             }
         }
 
@@ -3439,7 +3421,7 @@ impl VmConfig {
         // Remove if VFIO user device
         if let Some(user_devices) = self.user_devices.as_mut() {
             let len = user_devices.len();
-            user_devices.retain(|dev| dev.id.as_ref().map(|id| id.as_ref()) != Some(id));
+            user_devices.retain(|dev| dev.pci_common.id.as_ref().map(|id| id.as_ref()) != Some(id));
             removed |= user_devices.len() != len;
         }
 
@@ -5409,9 +5391,11 @@ id=\"{id}\",pci_segment={pci_segment},queue_sizes={queue_sizes}"
             ..platform_fixture()
         });
         invalid_config.user_devices = Some(vec![UserDeviceConfig {
-            pci_segment: 1,
+            pci_common: PciDeviceCommonConfig {
+                pci_segment: 1,
+                ..Default::default()
+            },
             socket: PathBuf::new(),
-            id: None,
         }]);
         assert_eq!(
             invalid_config.validate(),