Errors reported by tuned when using SecureBoot: Writing to file '/sys/kernel/debug/sched/migration_cost_ns' error: '[Errno 1] Operation not permitted: '/sys/kernel/debug/sched/migration_cost_ns''

When using SecureBoot tuned reports the following error as debugfs access is restricted:

tuned.utils.commands: Writing to file '/sys/kernel/debug/sched/migration_cost_ns' error: '[Errno 1] Operation not permitted: '/sys/kernel/debug/sched/migration_cost_ns''
tuned.plugins.plugin_scheduler: Error writing value '5000000' to 'migration_cost_ns'

4.14.0-rc.2

100%

1. Deploy SNO with SecureBoot enabled
2. Check tuned pod logs

2023-09-26 08:14:40,129 ERROR    tuned.utils.commands: Error when reading file '/sys/kernel/debug/sched/migration_cost_ns': '[Errno 1] Operation not permitted: '/sys/kernel/debug/sched/migration_cost_ns''
2023-09-26 08:14:40,130 ERROR    tuned.plugins.plugin_scheduler: Error reading 'migration_cost_ns'
2023-09-26 08:14:40,130 ERROR    tuned.plugins.plugin_scheduler: This may not work with Secure Boot or kernel_lockdown (this hint is logged only once)
2023-09-26 08:14:40,130 ERROR    tuned.utils.commands: Writing to file '/sys/kernel/debug/sched/migration_cost_ns' error: '[Errno 1] Operation not permitted: '/sys/kernel/debug/sched/migration_cost_ns''
2023-09-26 08:14:40,130 ERROR    tuned.plugins.plugin_scheduler: Error writing value '5000000' to 'migration_cost_ns'

No errors