libvirt: add auto-discovery support for device passthrough pools

Add a new flag in HostDevicePoolSchema to let lisa auto discover the
device pool.

Author: pupacha

lisa/sut_orchestrator/libvirt/libvirt_device_pool.py

@@ -180,6 +180,21 @@ def get_rootfs_nvme_iommu_group(self) -> str:
             sysfs_path, context="rootfs NVMe"
         )
 
+    def auto_discover_pool(self, pool_type: HostDevicePoolType) -> None:
+        self.available_host_devices[pool_type] = {}
+        candidates = self._get_passthrough_device_candidates(pool_type)
+        if not candidates:
+            raise LisaException(
+                f"Auto-discovery found no eligible devices for pool type "
+                f"'{pool_type.value}' on the host. Verify that devices of "
+                f"this type exist and are not excluded (primary NIC, etc)."
+            )
+        self.host_node.log.debug(
+            f"Auto-discovered {len(candidates)} device(s) for pool "
+            f"'{pool_type.value}': {candidates}"
+        )
+        self._create_pool(pool_type, candidates)
+
     def create_device_pool(
         self,
         pool_type: HostDevicePoolType,

lisa/sut_orchestrator/util/device_pool.py

@@ -82,6 +82,10 @@ def _validate_supported_pool_types(
                 )
 
     def _configure_passthrough_pool(self, config: HostDevicePoolSchema) -> None:
+        if config.auto_discover:
+            self.auto_discover_pool(config.type)
+            return
+
         devices = config.devices
         if self._is_vendor_device_id_list(devices):
             vendor_device_list = cast(List[VendorDeviceIdIdentifier], devices)
@@ -99,6 +103,9 @@ def _configure_passthrough_pool(self, config: HostDevicePoolSchema) -> None:
             f"Unknown device identifier of type: {type(devices)}" f", value: {devices}"
         )
 
+    def auto_discover_pool(self, pool_type: HostDevicePoolType) -> None:
+        raise NotImplementedError()
+
     def _is_vendor_device_id_list(self, devices: Any) -> bool:
         if not isinstance(devices, list):
             return False

lisa/sut_orchestrator/util/schema.py

@@ -44,6 +44,7 @@ class DeviceLocationPathIdentifier:
 @dataclass
 class HostDevicePoolSchema:
     type: HostDevicePoolType = HostDevicePoolType.PCI_NIC
+    auto_discover: bool = False
     devices: Union[
         List[VendorDeviceIdIdentifier],
         PciAddressIdentifier,