machine_os: Preemptively load vfio kernel module.

VFIO kernel module is not always loaded, which causes tests to fail
when they try to set No-IOMMU mode. This change calls modprobe to
ensure that VFIO is loaded before we try to use it.

(cherry picked from commit 0a01a10)
Signed-off-by: Martin Kalcok <martin.kalcok@canonical.com>

Author: mkalcok

unit_tests/utilities/test_zaza_utilities_machine_os.py

@@ -85,6 +85,7 @@ def test_add_netdevsim(self):
 
     def test__set_vfio_unsafe_noiommu_mode(self):
         self.patch_object(machine_os_utils.zaza.utilities.juju, 'remote_run')
+        self.patch_object(machine_os_utils, 'load_kernel_module')
         self.remote_run.return_value = 'Y'
         unit = mock.MagicMock()
         unit.name = 'aUnit'
@@ -97,6 +98,7 @@ def test__set_vfio_unsafe_noiommu_mode(self):
         with self.assertRaises(AssertionError):
             machine_os_utils._set_vfio_unsafe_noiommu_mode(unit, True)
 
+        self.load_kernel_module.reset_mock()
         self.remote_run.reset_mock()
         self.remote_run.return_value = 'Y\n'
         expect = (
@@ -105,7 +107,10 @@ def test__set_vfio_unsafe_noiommu_mode(self):
         machine_os_utils._set_vfio_unsafe_noiommu_mode(unit, True)
         self.remote_run.assert_called_once_with(
             'aUnit', expect, model_name=None, fatal=True)
+        self.load_kernel_module.assert_called_once_with(
+            'aUnit', 'vfio', model_name=None)
 
+        self.load_kernel_module.reset_mock()
         self.remote_run.reset_mock()
         self.remote_run.return_value = 'N\n'
         expect = (
@@ -114,6 +119,8 @@ def test__set_vfio_unsafe_noiommu_mode(self):
         machine_os_utils._set_vfio_unsafe_noiommu_mode(unit, False)
         self.remote_run.assert_called_once_with(
             'aUnit', expect, model_name=None, fatal=True)
+        self.load_kernel_module.assert_called_once_with(
+            'aUnit', 'vfio', model_name=None)
 
     def test_enable_vfio_unsafe_noiommu_mode(self):
         self.patch_object(machine_os_utils, '_set_vfio_unsafe_noiommu_mode')

zaza/utilities/machine_os.py

@@ -133,6 +133,8 @@ def _set_vfio_unsafe_noiommu_mode(unit, enable, model_name=None):
     :type model_name: Optional[str]
     :raises: AssertionError, zaza.model.CommandRunFailed
     """
+    load_kernel_module(unit.name, 'vfio', model_name=model_name)
+
     expected_result = 'Y' if enable else 'N'
     value = 1 if enable else 0
     cmd = (