1 files changed, 157 insertions, 0 deletions
diff --git a/nova/virt/libvirt/cpu/api.py b/nova/virt/libvirt/cpu/api.py
new file mode 100644
index 0000000000..1c17458d6b
--- /dev/null
+++ b/nova/virt/libvirt/cpu/api.py
@@ -0,0 +1,157 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from dataclasses import dataclass
+
+from oslo_log import log as logging
+
+import nova.conf
+from nova import exception
+from nova.i18n import _
+from nova import objects
+from nova.virt import hardware
+from nova.virt.libvirt.cpu import core
+
+LOG = logging.getLogger(__name__)
+
+CONF = nova.conf.CONF
+
+
+@dataclass
+class Core:
+    """Class to model a CPU core as reported by sysfs.
+
+    It may be a physical CPU core or a hardware thread on a shared CPU core
+    depending on if the system supports SMT.
+    """
+
+    # NOTE(sbauza): ident is a mandatory field.
+    # The CPU core id/number
+    ident: int
+
+    @property
+    def online(self) -> bool:
+        return core.get_online(self.ident)
+
+    @online.setter
+    def online(self, state: bool) -> None:
+        if state:
+            core.set_online(self.ident)
+        else:
+            core.set_offline(self.ident)
+
+    def __hash__(self):
+        return hash(self.ident)
+
+    def __eq__(self, other):
+        return self.ident == other.ident
+
+    def __str__(self):
+        return str(self.ident)
+
+    @property
+    def governor(self) -> str:
+        return core.get_governor(self.ident)
+
+    def set_high_governor(self) -> None:
+        core.set_governor(self.ident, CONF.libvirt.cpu_power_governor_high)
+
+    def set_low_governor(self) -> None:
+        core.set_governor(self.ident, CONF.libvirt.cpu_power_governor_low)
+
+
+def power_up(instance: objects.Instance) -> None:
+    if not CONF.libvirt.cpu_power_management:
+        return
+    if instance.numa_topology is None:
+        return
+
+    cpu_dedicated_set = hardware.get_cpu_dedicated_set() or set()
+    pcpus = instance.numa_topology.cpu_pinning
+    powered_up = set()
+    for pcpu in pcpus:
+        if pcpu in cpu_dedicated_set:
+            pcpu = Core(pcpu)
+            if CONF.libvirt.cpu_power_management_strategy == 'cpu_state':
+                pcpu.online = True
+            else:
+                pcpu.set_high_governor()
+            powered_up.add(str(pcpu))
+    LOG.debug("Cores powered up : %s", powered_up)
+
+
+def power_down(instance: objects.Instance) -> None:
+    if not CONF.libvirt.cpu_power_management:
+        return
+    if instance.numa_topology is None:
+        return
+
+    cpu_dedicated_set = hardware.get_cpu_dedicated_set() or set()
+    pcpus = instance.numa_topology.cpu_pinning
+    powered_down = set()
+    for pcpu in pcpus:
+        if pcpu in cpu_dedicated_set:
+            pcpu = Core(pcpu)
+            if CONF.libvirt.cpu_power_management_strategy == 'cpu_state':
+                pcpu.online = False
+            else:
+                pcpu.set_low_governor()
+            powered_down.add(str(pcpu))
+    LOG.debug("Cores powered down : %s", powered_down)
+
+
+def power_down_all_dedicated_cpus() -> None:
+    if not CONF.libvirt.cpu_power_management:
+        return
+    if (CONF.libvirt.cpu_power_management and
+        not CONF.compute.cpu_dedicated_set
+    ):
+        msg = _("'[compute]/cpu_dedicated_set' is mandatory to be set if "
+                "'[libvirt]/cpu_power_management' is set."
+                "Please provide the CPUs that can be pinned or don't use the "
+                "power management if you only use shared CPUs.")
+        raise exception.InvalidConfiguration(msg)
+
+    cpu_dedicated_set = hardware.get_cpu_dedicated_set() or set()
+    for pcpu in cpu_dedicated_set:
+        pcpu = Core(pcpu)
+        if CONF.libvirt.cpu_power_management_strategy == 'cpu_state':
+            pcpu.online = False
+        else:
+            pcpu.set_low_governor()
+    LOG.debug("Cores powered down : %s", cpu_dedicated_set)
+
+
+def validate_all_dedicated_cpus() -> None:
+    if not CONF.libvirt.cpu_power_management:
+        return
+    cpu_dedicated_set = hardware.get_cpu_dedicated_set() or set()
+    governors = set()
+    cpu_states = set()
+    for pcpu in cpu_dedicated_set:
+        pcpu = Core(pcpu)
+        # we need to collect the governors strategy and the CPU states
+        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
+        if len(governors) > 1:
+            msg = _("All the cores need to have the same governor strategy"
+                    "before modifying the CPU states. You can reboot the "
+                    "compute node if you prefer.")
+            raise exception.InvalidConfiguration(msg)
+    elif CONF.libvirt.cpu_power_management_strategy == 'governor':
+        # all the cores need to be online
+        if False in cpu_states:
+            msg = _("All the cores need to be online before modifying the "
+                    "governor strategy.")
+            raise exception.InvalidConfiguration(msg)