From 39c184a6a9a7a99950b321d55fe713175cf1d404 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Wed, 27 Apr 2022 09:08:52 +0300 Subject: intel_idle: Fix the 'preferred_cstates' module parameter Problem description. When user boots kernel up with the 'intel_idle.preferred_cstates=4' option, we enable C1E and disable C1 states on Sapphire Rapids Xeon (SPR). In order for C1E to work on SPR, we have to enable the C1E promotion bit on all CPUs. However, we enable it only on one CPU. Fix description. The 'intel_idle' driver already has the infrastructure for disabling C1E promotion on every CPU. This patch uses the same infrastructure for enabling C1E promotion on every CPU. It changes the boolean 'disable_promotion_to_c1e' variable to a tri-state 'c1e_promotion' variable. Tested on a 2-socket SPR system. I verified the following combinations: * C1E promotion enabled and disabled in BIOS. * Booted with and without the 'intel_idle.preferred_cstates=4' kernel argument. In all 4 cases C1E promotion was correctly set on all CPUs. Also tested on an old Broadwell system, just to make sure it does not cause a regression. C1E promotion was correctly disabled on that system, both C1 and C1E were exposed (as expected). Fixes: da0e58c038e6 ("intel_idle: add 'preferred_cstates' module argument") Reported-by: Jan Beulich Signed-off-by: Artem Bityutskiy [ rjw: Minor changelog edits ] Signed-off-by: Rafael J. Wysocki --- drivers/idle/intel_idle.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) (limited to 'drivers') diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index b7640cfe0020..cf5ed4c1d02c 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -69,7 +69,12 @@ static unsigned int preferred_states_mask; static struct cpuidle_device __percpu *intel_idle_cpuidle_devices; static unsigned long auto_demotion_disable_flags; -static bool disable_promotion_to_c1e; + +static enum { + C1E_PROMOTION_PRESERVE, + C1E_PROMOTION_ENABLE, + C1E_PROMOTION_DISABLE +} c1e_promotion = C1E_PROMOTION_PRESERVE; struct idle_cpu { struct cpuidle_state *state_table; @@ -1398,8 +1403,6 @@ static inline void intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) { } static inline bool intel_idle_off_by_default(u32 mwait_hint) { return false; } #endif /* !CONFIG_ACPI_PROCESSOR_CSTATE */ -static void c1e_promotion_enable(void); - /** * ivt_idle_state_table_update - Tune the idle states table for Ivy Town. * @@ -1587,8 +1590,7 @@ static void __init spr_idle_state_table_update(void) spr_cstates[1].flags &= ~CPUIDLE_FLAG_UNUSABLE; /* Enable C1E using the "C1E promotion" bit. */ - c1e_promotion_enable(); - disable_promotion_to_c1e = false; + c1e_promotion = C1E_PROMOTION_ENABLE; } /* @@ -1754,7 +1756,9 @@ static int intel_idle_cpu_init(unsigned int cpu) if (auto_demotion_disable_flags) auto_demotion_disable(); - if (disable_promotion_to_c1e) + if (c1e_promotion == C1E_PROMOTION_ENABLE) + c1e_promotion_enable(); + else if (c1e_promotion == C1E_PROMOTION_DISABLE) c1e_promotion_disable(); return 0; @@ -1833,7 +1837,8 @@ static int __init intel_idle_init(void) if (icpu) { cpuidle_state_table = icpu->state_table; auto_demotion_disable_flags = icpu->auto_demotion_disable_flags; - disable_promotion_to_c1e = icpu->disable_promotion_to_c1e; + if (icpu->disable_promotion_to_c1e) + c1e_promotion = C1E_PROMOTION_DISABLE; if (icpu->use_acpi || force_use_acpi) intel_idle_acpi_cst_extract(); } else if (!intel_idle_acpi_cst_extract()) { -- cgit v1.2.3 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') 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