Revert "[pwmgmt]ignore missin governor when cpu_state used"

This reverts commit 41096f8 as it has a
bug in it expecting a wrong exception type (FileNotFoundError vs
nova.exception.FileNotFound). Also there is a proper fix on master
2c44215 that can be backported instead.

Change-Id: Id2c253a6e223bd5ba22512d9e5a40a9d12680da2
(cherry picked from commit 03ef4d6)
(cherry picked from commit 25d0db7)

Author: gibizer

nova/tests/unit/virt/libvirt/cpu/test_api.py

@@ -237,42 +237,3 @@ def test_validate_all_dedicated_cpus_no_cpu(self):
         api.validate_all_dedicated_cpus()
         # no assert we want to make sure the validation won't raise if
         # no dedicated cpus are configured
-
-    @mock.patch.object(core, 'get_governor')
-    @mock.patch.object(core, 'get_online')
-    def test_validate_all_dedicated_cpus_for_cpu_state_no_governor_ignored(
-        self, mock_get_online, mock_get_governor
-    ):
-        self.flags(cpu_power_management=True, group='libvirt')
-        self.flags(cpu_dedicated_set='0-2', group='compute')
-        self.flags(cpu_power_management_strategy='cpu_state', group='libvirt')
-
-        mock_get_online.return_value = True
-        mock_get_governor.side_effect = FileNotFoundError(
-            "File /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor "
-            "could not be found.")
-
-        api.validate_all_dedicated_cpus()
-
-        self.assertEqual(2, len(mock_get_governor.mock_calls))
-
-    @mock.patch.object(core, 'get_governor')
-    @mock.patch.object(core, 'get_online')
-    def test_validate_all_dedicated_cpus_for_governor_error(
-        self, mock_get_online, mock_get_governor
-    ):
-        self.flags(cpu_power_management=True, group='libvirt')
-        self.flags(cpu_dedicated_set='0-2', group='compute')
-        self.flags(cpu_power_management_strategy='governor', group='libvirt')
-
-        mock_get_online.return_value = True
-        mock_get_governor.side_effect = FileNotFoundError(
-            "File /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor "
-            "could not be found.")
-
-        ex = self.assertRaises(
-            exception.InvalidConfiguration, api.validate_all_dedicated_cpus)
-        self.assertIn(
-            "[libvirt]cpu_power_management_strategy is 'governor', "
-            "but the host OS does not support governors for CPU0",
-            str(ex))

nova/virt/libvirt/cpu/api.py

@@ -137,24 +137,7 @@ def validate_all_dedicated_cpus() -> None:
             continue
         pcpu = Core(pcpu)
         # we need to collect the governors strategy and the CPU states
-        try:
-            governors.add(pcpu.governor)
-        except FileNotFoundError as e:
-            # NOTE(gibi): When
-            # /sys/devices/system/cpu/cpuX/cpufreq/scaling_governor does
-            # not exist it means the host OS does not support any governors.
-            # If cpu_state strategy is requested we can ignore this as
-            # governors will not be used but if governor strategy is requested
-            # we need to report an error and stop as the host is not properly
-            # configured
-            if CONF.libvirt.cpu_power_management_strategy == 'governor':
-                msg = _(
-                    "[libvirt]cpu_power_management_strategy is 'governor', "
-                    "but the host OS does not support governors for CPU%d"
-                    % pcpu.ident
-                )
-                raise exception.InvalidConfiguration(msg) from e
-
+        governors.add(pcpu.governor)
         cpu_states.add(pcpu.online)
     if CONF.libvirt.cpu_power_management_strategy == 'cpu_state':
         # all the cores need to have the same governor strategy