CPU state management fails if cpu0 is in dedicated set

[Dan Smith]

If an operator configures cpu0 in the dedicated set and enables state management, nova-compute will fail on startup with this obscure error:

Oct 06 20:08:43.195137 np0035436890 nova-compute[104711]: ERROR oslo_service.service nova.exception.FileNotFound: File /sys/devices/system/cpu/cpu0/online could not be found.

The problem is that cpu0 is not hot-pluggable and thus has no online knob. Nova should log a better error message in this case, at least.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/nova/+/898137

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/898137
Committed: https://opendev.org/openstack/nova/commit/0b9d8cee580739e7a4e2a769e4d4e35110a6bc49
Submitter: "Zuul (22348)"
Branch: master

commit 0b9d8cee580739e7a4e2a769e4d4e35110a6bc49
Author: Dan Smith <email address hidden>
Date: Thu Oct 12 12:12:53 2023 -0700

    Do not manage CPU0's state

    If cpu_power_management_strategy is "cpu_state" and CPU0 is in the
    dedicated set, we should just ignore it whenever we go to manage the
    state. Since CPU0 cannot be powered off, but may be otherwise suitable
    for the dedicated set, we can just skip it whenever we would normally
    go to power it up or down.

    Change-Id: I995c0953b361c7016bd77482fa2e2f276d239828
    Fixes-Bug: #2038840

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/2023.2
Review: https://review.opendev.org/c/openstack/nova/+/901566

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/2023.1
Review: https://review.opendev.org/c/openstack/nova/+/901567

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/901566
Committed: https://opendev.org/openstack/nova/commit/9cee58c6e4730fbc20534d73c710900203a30c57
Submitter: "Zuul (22348)"
Branch: stable/2023.2

commit 9cee58c6e4730fbc20534d73c710900203a30c57
Author: Dan Smith <email address hidden>
Date: Thu Oct 12 12:12:53 2023 -0700

    Do not manage CPU0's state

    If cpu_power_management_strategy is "cpu_state" and CPU0 is in the
    dedicated set, we should just ignore it whenever we go to manage the
    state. Since CPU0 cannot be powered off, but may be otherwise suitable
    for the dedicated set, we can just skip it whenever we would normally
    go to power it up or down.

    Change-Id: I995c0953b361c7016bd77482fa2e2f276d239828
    Fixes-Bug: #2038840
    (cherry picked from commit 0b9d8cee580739e7a4e2a769e4d4e35110a6bc49)

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/901567
Committed: https://opendev.org/openstack/nova/commit/d7ea3a184bda264998d6e2f85aee17f01c4a45e2
Submitter: "Zuul (22348)"
Branch: stable/2023.1

commit d7ea3a184bda264998d6e2f85aee17f01c4a45e2
Author: Dan Smith <email address hidden>
Date: Thu Oct 12 12:12:53 2023 -0700

    Do not manage CPU0's state

    If cpu_power_management_strategy is "cpu_state" and CPU0 is in the
    dedicated set, we should just ignore it whenever we go to manage the
    state. Since CPU0 cannot be powered off, but may be otherwise suitable
    for the dedicated set, we can just skip it whenever we would normally
    go to power it up or down.

    Change-Id: I995c0953b361c7016bd77482fa2e2f276d239828
    Fixes-Bug: #2038840
    (cherry picked from commit 0b9d8cee580739e7a4e2a769e4d4e35110a6bc49)
    (cherry picked from commit 9cee58c6e4730fbc20534d73c710900203a30c57)