utils_kernel_module: filter out not applicable module parameters

When reading kernel module parameters from sysfs, some parameters may
return the string "not required" if they are not applicable, for
example module kvm_intel parameter vmentry_l1d_flush. Previously,
these values were included in the parameter string passed to
modprobe when restoring the module, which leads to module
loading failure.
This change introduces new parameters "kvm_module_ignored_parameters"
and "kvm_probe_module_ignored_parameters", (e.g., "vmentry_l1d_flush=not required")
to skip the parameters.

Signed-off-by: Liang Cong <lcong@redhat.com>

Author: liang-cong-red-hat

virttest/shared/cfg/base.cfg

@@ -1225,3 +1225,18 @@ uuid_dimm = ""
 # enable_igvm = no
 # igvm_path = /usr/share/coconut-svsm
 # igvm_filename = coconut-qemu.igvm
+
+# KVM Module Reload/Restore Settings for Test Pre-processing and Post-processing
+# ---------------------------------------------------------
+# Force reload KVM module
+#kvm_module_force_load = yes
+# Force reload vendor-specific module (kvm_intel/kvm_amd)
+#kvm_probe_module_force_load = yes
+# Parameters for KVM module (e.g., "nested=1")
+#kvm_module_parameters = "nested=1"
+# Parameters for vendor-specific module (e.g., "tdx=1")
+#kvm_probe_module_parameters = "tdx=1"
+# Values to ignore when backing up/restoring KVM module params
+#kvm_module_ignored_parameters = vmentry_l1d_flush=not required
+# Values to ignore when backing up/restoring vendor-specific module (kvm_intel/kvm_amd) params
+#kvm_probe_module_ignored_parameters = vmentry_l1d_flush=not required

virttest/test_setup/kernel.py

@@ -1,3 +1,5 @@
+import re
+
 from virttest import arch, test_setup, utils_kernel_module
 from virttest.test_setup.core import Setuper
 
@@ -7,10 +9,30 @@ def __init__(self, test, params, env):
         super().__init__(test, params, env)
         self.kvm_module_handlers = []
 
+    def _get_param_prefix(self, module_name):
+        """Determine parameter prefix based on module name."""
+        return "kvm" if module_name == "kvm" else "kvm_probe"
+
+    def _parse_ignored_params(self, ignored_params):
+        """
+        Parse ignored parameters string into a list of 'key=value' pairs.
+
+        :param ignored_params: string contains parameters to ignore
+        :return: list of 'key=value' strings
+        """
+        ignored_list = []
+        if not ignored_params:
+            return ignored_list
+
+        pattern = r'(\w+)=(?:["\']([^"\']*)["\']|(.*?))(?=\s+\w+=|$)'
+        matches = re.findall(pattern, ignored_params)
+        ignored_list = ["%s=%s" % (k, (q or u).strip()) for k, q, u in matches]
+        return ignored_list
+
     def setup(self):
         kvm_modules = arch.get_kvm_module_list()
         for module in reversed(kvm_modules):
-            param_prefix = module if module == "kvm" else "kvm_probe"
+            param_prefix = self._get_param_prefix(module)
             module_force_load = self.params.get_boolean(
                 "%s_module_force_load" % param_prefix
             )
@@ -25,7 +47,12 @@ def setup(self):
 
     def cleanup(self):
         for kvm_module in self.kvm_module_handlers:
-            kvm_module.restore()
+            param_prefix = self._get_param_prefix(kvm_module.module_name)
+            module_ignored_parameters = self.params.get(
+                "%s_module_ignored_parameters" % param_prefix
+            )
+            ignored_list = self._parse_ignored_params(module_ignored_parameters)
+            kvm_module.restore(ignored_list)
 
 
 class KSMSetup(Setuper):

virttest/utils_kernel_module.py

@@ -18,6 +18,7 @@
 
 import logging
 import os
+import re
 
 from avocado.utils import process
 
@@ -164,10 +165,26 @@ def reload_module(self, force, params=""):
         for holder in self._module_holders:
             holder.restore()
 
-    def restore(self):
+    def _remove_key_value_pair(self, original, target):
+        """
+        Remove target key=value pair from a space-separated config string
+
+        :param original: source string with space-separated key=value pairs
+        :param target: specific key=value pair to remove
+        :return: modified string with the target pair removed if found
+        """
+
+        pattern = r"(\w+=\S+(?:\s+(?!\w+=)\S+)*)"
+        parts = re.findall(pattern, original)
+        result_parts = [p for p in parts if p.strip() != target.strip()]
+        return " ".join(result_parts)
+
+    def restore(self, ignored_params=None):
         """
         Restore previous module state.
 
+        :param ignored_params: params list to be ignored for module restore
+
         The state will only be restored if the original state
         was altered.
 
@@ -188,9 +205,16 @@ def restore(self):
             # TODO: Handle cases were module cannot be removed
             self.unload_module()
             if self._was_loaded:
+                restore_config = self._config_backup
+                if ignored_params:
+                    for param in ignored_params:
+                        restore_config = self._remove_key_value_pair(
+                            restore_config, param
+                        )
+                        LOG.debug("Module restore ignores parameter '%s'.", param)
                 restore_cmd = "modprobe %s %s" % (
                     self._module_name,
-                    self._config_backup,
+                    restore_config,
                 )
                 LOG.debug("Restoring module state: %s", restore_cmd)
                 status, output = process.getstatusoutput(restore_cmd)
@@ -217,6 +241,12 @@ def _backup_config(self):
             self._config_backup,
         )
 
+    @property
+    def module_name(self):
+        """Read-only property"""
+
+        return self._module_name
+
     @property
     def was_loaded(self):
         """Read-only property"""