From 249735c48fb24cff44957f7d0bcb6cbf1f29fc4c Mon Sep 17 00:00:00 2001 From: Len Brown Date: Tue, 9 Sep 2014 18:10:21 +0200 Subject: [PATCH] x86/mwait-idle: disable Baytrail Core and Module C6 auto-demotion Power efficiency improves on Baytrail (Intel Atom Processor E3000) when Linux disables C6 auto-demotion. Based on work by Srinidhi Kasagar . Signed-off-by: Len Brown Do the MSR writes on all CPUs rather than just the current one. Signed-off-by: Jan Beulich --- xen/arch/x86/cpu/mwait-idle.c | 11 +++++++++++ xen/include/asm-x86/msr-index.h | 3 +++ 2 files changed, 14 insertions(+) diff --git a/xen/arch/x86/cpu/mwait-idle.c b/xen/arch/x86/cpu/mwait-idle.c index c2c8889a69..a4a779ba53 100644 --- a/xen/arch/x86/cpu/mwait-idle.c +++ b/xen/arch/x86/cpu/mwait-idle.c @@ -88,6 +88,7 @@ struct idle_cpu { * Indicate which enable bits to clear here. */ unsigned long auto_demotion_disable_flags; + bool_t byt_auto_demotion_disable_flag; bool_t disable_promotion_to_c1e; }; @@ -537,6 +538,12 @@ static void auto_demotion_disable(void *dummy) wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits); } +static void byt_auto_demotion_disable(void *dummy) +{ + wrmsrl(MSR_CC6_DEMOTION_POLICY_CONFIG, 0); + wrmsrl(MSR_MC6_DEMOTION_POLICY_CONFIG, 0); +} + static void c1e_promotion_disable(void *dummy) { u64 msr_bits; @@ -569,6 +576,7 @@ static const struct idle_cpu idle_cpu_snb = { static const struct idle_cpu idle_cpu_byt = { .state_table = byt_cstates, .disable_promotion_to_c1e = 1, + .byt_auto_demotion_disable_flag = 1, }; static const struct idle_cpu idle_cpu_ivb = { @@ -767,6 +775,9 @@ static int mwait_idle_cpu_init(struct notifier_block *nfb, if (icpu->auto_demotion_disable_flags) on_selected_cpus(cpumask_of(cpu), auto_demotion_disable, NULL, 1); + if (icpu->byt_auto_demotion_disable_flag) + on_selected_cpus(cpumask_of(cpu), byt_auto_demotion_disable, NULL, 1); + if (icpu->disable_promotion_to_c1e) on_selected_cpus(cpumask_of(cpu), c1e_promotion_disable, NULL, 1); diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h index 2056501f87..542222e07a 100644 --- a/xen/include/asm-x86/msr-index.h +++ b/xen/include/asm-x86/msr-index.h @@ -483,4 +483,7 @@ #define _MSR_MISC_FEATURES_CPUID_FAULTING 0 #define MSR_MISC_FEATURES_CPUID_FAULTING (1ULL << _MSR_MISC_FEATURES_CPUID_FAULTING) +#define MSR_CC6_DEMOTION_POLICY_CONFIG 0x00000668 +#define MSR_MC6_DEMOTION_POLICY_CONFIG 0x00000669 + #endif /* __ASM_MSR_INDEX_H */ -- 2.30.2