From 7eac3bd38d18cd3317756649921b8264ddfee692 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Wed, 27 Apr 2022 09:08:53 +0300 Subject: intel_idle: Fix SPR C6 optimization The Sapphire Rapids (SPR) C6 optimization was added to the end of the 'spr_idle_state_table_update()' function. However, the function has a 'return' which may happen before the optimization has a chance to run. And this may prevent the optimization from happening. This is an unlikely scenario, but possible if user boots with, say, the 'intel_idle.preferred_cstates=6' kernel boot option. This patch fixes the issue by eliminating the problematic 'return' statement. Fixes: 3a9cf77b60dc ("intel_idle: add core C6 optimization for SPR") Suggested-by: Jan Beulich Reported-by: Jan Beulich Signed-off-by: Artem Bityutskiy [ rjw: Minor changelog edits ] Signed-off-by: Rafael J. Wysocki --- drivers/idle/intel_idle.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'drivers/idle') diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index cf5ed4c1d02c..47551ab73ca8 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -1581,11 +1581,9 @@ static void __init spr_idle_state_table_update(void) unsigned long long msr; /* Check if user prefers C1E over C1. */ - if (preferred_states_mask & BIT(2)) { - if (preferred_states_mask & BIT(1)) - /* Both can't be enabled, stick to the defaults. */ - return; - + if ((preferred_states_mask & BIT(2)) && + !(preferred_states_mask & BIT(1))) { + /* Disable C1 and enable C1E. */ spr_cstates[0].flags |= CPUIDLE_FLAG_UNUSABLE; spr_cstates[1].flags &= ~CPUIDLE_FLAG_UNUSABLE; -- cgit v1.2.3