linux-kernel - [PATCH v9 0/4] SRF: Fix offline CPU preventing pc6 entry

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Message-ID: <20250110115953.6058-1-patryk.wlazlyn@linux.intel.com>
Date: Fri, 10 Jan 2025 12:59:49 +0100
From: Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	rafael.j.wysocki@...el.com,
	len.brown@...el.com,
	artem.bityutskiy@...ux.intel.com,
	dave.hansen@...ux.intel.com,
	patryk.wlazlyn@...ux.intel.com
Subject: [PATCH v9 0/4] SRF: Fix offline CPU preventing pc6 entry

Code for determining the mwait hint for the deepest C-state by
inspecting CPUID leaf 0x5 in mwait_play_dead() assumes that, if the
number of sub-states for a given major C-state is nonzero, those
sub-states are always represented by consecutive numbers starting from
0. This assumption is not based on the documented platform behavior and
in fact it is not met on recent Intel platforms.

Changes since v8:
  * Revert the deletion of cpuidle_state_table check for enter and
    s2idle handlers in intel_idle in 3/4:
-               if (!cpuidle_state_table[cstate].enter &&
-                   !cpuidle_state_table[cstate].enter_s2idle)
+               if (!cpuidle_state_table[cstate].enter)

  * Apply the changelog wording suggested by Rafael in v8 review.

Patryk Wlazlyn (4):
  x86/smp: Allow calling mwait_play_dead with an arbitrary hint
  ACPI: processor_idle: Add FFH state handling
  intel_idle: Provide the default enter_dead() handler
  x86/smp: Eliminate mwait_play_dead_cpuid_hint()

 arch/x86/include/asm/smp.h    |  3 +++
 arch/x86/kernel/acpi/cstate.c | 10 ++++++++
 arch/x86/kernel/smpboot.c     | 46 ++++-------------------------------
 drivers/acpi/processor_idle.c |  2 ++
 drivers/idle/intel_idle.c     | 15 ++++++++++++
 include/acpi/processor.h      |  5 ++++
 6 files changed, 40 insertions(+), 41 deletions(-)

-- 
2.47.1