Native IRQ affinity is not restored after the first cycle in multi-state configurations

[karuboniru]

Without irqbalance , intel-lpmd uses its native IRQ migration path. With a configuration containing the following states:

State	Active CPUs	IRQMigrate
ECORE_ONE_MODULE	16-19	1
ECORE_TWO_MODULES	12-19	1
FULL_POWER	0-19	-2 (SETTING_RESTORE)

In a multi-state cycle, IRQ affinity is restored correctly only the first time.

During the first transition to a restricted state, the native implementation saves each IRQ's original smp_affinity while irq_updated is false. After updating the IRQs, it sets irq_updated to 1.

When entering FULL_POWER, IRQMigrate=-2 selects the native restore path. native_restore_irqs() restores the cached affinities and clears the cache with memset(), but it does not reset irq_updated to 0.

Consequently, during the next low-power cycle, irq_updated is still 1, so the original IRQ affinities are not cached again. The IRQs are restricted to the selected cluster, but the following FULL_POWER transition has an empty cache and therefore restores nothing. The state machine still applies the FULL_POWER CPU configuration after processing IRQs, because process_cgroup() is called after process_irq().

For example, after the second ECORE_TWO_MODULES -> FULL_POWER transition, the system can end up in the following inconsistent state:

CPU affinity: 0-19
IRQ affinity: 12-19

If the transition passes through ECORE_ONE_MODULE, IRQ affinity may remain restricted to 16-19 instead.

Expected behavior: every FULL_POWER transition with IRQMigrate=-2 restores the IRQ affinities that existed before the corresponding low-power cycle.

Actual behavior: only the first restore succeeds; subsequent restores leave IRQ affinity restricted to the last low-power cluster.

---

<?xml version="1.0"?>

<Configuration>
    <lp_mode_cpus></lp_mode_cpus>
    <lp_mode_epp>-1</lp_mode_epp>
    <Mode>1</Mode>
    <PerformanceDef>-1</PerformanceDef>
    <BalancedDef>0</BalancedDef>
    <PowersaverDef>1</PowersaverDef>
    <HfiLpmEnable>0</HfiLpmEnable>
    <WLTHintEnable>0</WLTHintEnable>
    <util_entry_threshold>10</util_entry_threshold>
    <util_exit_threshold>95</util_exit_threshold>
    <IgnoreITMT>1</IgnoreITMT>

      <States>
          <CPUFamily>6</CPUFamily>
          <CPUModel>186</CPUModel>
          <CPUConfig>*</CPUConfig>
          <State>
              <ID>1</ID>
              <Name>ECORE_ONE_MODULE</Name>
              <EntrySystemLoadThres>2</EntrySystemLoadThres>
              <EnterCPULoadThres>50</EnterCPULoadThres>

              <ActiveCPUs>16-19</ActiveCPUs>

              <EPP>-1</EPP>
              <EPB>-1</EPB>
              <ITMTState>-1</ITMTState>
              <IRQMigrate>1</IRQMigrate>

              <MinPollInterval>500</MinPollInterval>
              <PollIntervalIncrement>-1</PollIntervalIncrement>
              <MaxPollInterval>2000</MaxPollInterval>
          </State>
          <State>
              <ID>2</ID>
              <Name>ECORE_TWO_MODULES</Name>
              <EntrySystemLoadThres>10</EntrySystemLoadThres>
              <EnterCPULoadThres>95</EnterCPULoadThres>

              <ActiveCPUs>12-19</ActiveCPUs>

              <EPP>-1</EPP>
              <EPB>-1</EPB>
              <ITMTState>-1</ITMTState>
              <IRQMigrate>1</IRQMigrate>

              <MinPollInterval>500</MinPollInterval>
              <PollIntervalIncrement>-1</PollIntervalIncrement>
              <MaxPollInterval>2000</MaxPollInterval>
          </State>
          <State>
              <ID>3</ID>
              <Name>FULL_POWER</Name>

              <ActiveCPUs>0-19</ActiveCPUs>

              <EPP>-1</EPP>
              <EPB>-1</EPB>
              <ITMTState>-1</ITMTState>

              <IRQMigrate>-2</IRQMigrate>

              <MinPollInterval>500</MinPollInterval>
              <PollIntervalIncrement>-1</PollIntervalIncrement>
              <MaxPollInterval>2000</MaxPollInterval>
          </State>
      </States>

</Configuration>