Excluded unsupported Hyper-v modules in hv_modules tests for CVMs. (#4512)

CVMs do not surface emulated input devices or framebuffer/DRM over VMBus, so the corresponding kernel modules are intentionally absent in CVMs.
Reference: https://elixir.bootlin.com/linux/v7.0/source/drivers/hv/channel_mgmt.c#L31
In the above file only modules with ".allowed_in_isolated = true," are available in CVMs.
Below are modules that are not exposed to a guest when running as a Confidential VM.
- hid_hyperv
- hyperv_keyboard
- hyperv_fb
- hyperv_drm

These modules should be skipped in checks for module presence and in reload tests on CVMs.

Author: SRIKKANTH

lisa/features/security_profile.py

@@ -166,3 +166,23 @@ def enabled(self) -> bool:
     security_profile=search_space.SetSpace(True, [SecurityProfileType.CVM]),
     encrypt_disk=True,
 )
+
+
+def is_cvm(node: Any) -> bool:
+    """
+    Returns True if the node is provisioned as a Confidential VM.
+
+    Falls back to False when the platform does not expose a SecurityProfile
+    feature (e.g. ready / hyperv platforms), so callers can use this as a
+    guard without extra checks.
+    """
+    try:
+        settings = Feature.get_feature_settings(
+            node.features[SecurityProfile].get_settings()
+        )
+    except Exception:
+        return False
+    return (
+        isinstance(settings, SecurityProfileSettings)
+        and settings.security_profile == SecurityProfileType.CVM
+    )

lisa/microsoft/testsuites/core/hv_module.py

@@ -15,13 +15,33 @@
     TestSuiteMetadata,
     simple_requirement,
 )
+from lisa.features.security_profile import is_cvm
 from lisa.operating_system import BSD, Redhat
 from lisa.sut_orchestrator import AZURE, HYPERV, READY
 from lisa.sut_orchestrator.azure.platform_ import AzurePlatform
 from lisa.tools import KernelConfig, LisDriver, Lsinitrd, Lsmod, Modinfo, Modprobe
 from lisa.tools.kernel_config import ModulesType
 from lisa.util import LisaException, SkippedException
 
+# CVMs do not surface emulated input devices or framebuffer/DRM over VMBus,
+# so the corresponding kernel modules are intentionally absent in CVMs.
+# Reference:
+# https://elixir.bootlin.com/linux/v7.0/source/drivers/hv/channel_mgmt.c#L31
+# In the above file only modules with ".allowed_in_isolated = true," are available
+# in CVMs.
+# Below are modules that are not exposed to a guest when running as a Confidential VM.
+# These modules should be skipped in checks for module presence and in reload tests on
+# CVMs.
+
+_CVM_UNAVAILABLE_MODULES = frozenset(
+    {
+        "hid_hyperv",
+        "hyperv_keyboard",
+        "hyperv_fb",
+        "hyperv_drm",
+    }
+)
+
 
 @TestSuiteMetadata(
     area="core",
@@ -95,6 +115,11 @@ def verify_initrd_modules(self, environment: Environment) -> None:
             "hyperv_keyboard": "hyperv-keyboard.ko",
         }
         skip_modules = self._get_built_in_modules(node)
+        # CVMs do not have host-emulated input/display devices, so the
+        # corresponding modules are legitimately absent from initrd. Treat
+        # them as built-in for the purposes of this check.
+        if is_cvm(node):
+            skip_modules = list(set(skip_modules) | _CVM_UNAVAILABLE_MODULES)
         hv_modules_file_names = {
             k: v
             for (k, v) in all_necessary_hv_modules_file_names.items()
@@ -194,6 +219,11 @@ def verify_hyperv_modules(self, log: Logger, environment: Environment) -> None:
 
         if isinstance(environment.platform, AzurePlatform):
             missing_modules.discard("hid_hyperv")
+        # CVMs legitimately do not load host-emulated input or framebuffer
+        # modules, so absence is expected and must not fail this test.
+        if is_cvm(node):
+            for module in _CVM_UNAVAILABLE_MODULES:
+                missing_modules.discard(module)
         if not ("hyperv_fb" in missing_modules and "hyperv_drm" in missing_modules):
             # as long as both of these modules are not missing, we are OK to pass.
             missing_modules.discard("hyperv_fb")
@@ -237,8 +267,15 @@ def verify_reload_hyperv_modules(self, log: Logger, node: Node) -> None:
         loadable_modules = set(
             self._get_modules_by_type(node, module_type=ModulesType.MODULE)
         )
+        node_is_cvm = is_cvm(node)
 
         for module in hv_modules:
+            if node_is_cvm and module in _CVM_UNAVAILABLE_MODULES:
+                log.debug(
+                    f"{module} is not available on Confidential VMs, skipping reload"
+                )
+                skipped_modules.append(module)
+                continue
             if module not in loadable_modules:
                 log.debug(f"{module} is not a reloadable module")
                 skipped_modules.append(module)