diff options
| -rw-r--r-- | Documentation/admin-guide/pm/intel_epb.rst | 6 | ||||
| -rw-r--r-- | Documentation/admin-guide/pm/working-state.rst | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 17 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/cpu.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 34 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel_epb.c | 131 | ||||
| -rw-r--r-- | include/linux/cpuhotplug.h | 1 |
8 files changed, 140 insertions, 53 deletions
diff --git a/Documentation/admin-guide/pm/intel_epb.rst b/Documentation/admin-guide/pm/intel_epb.rst new file mode 100644 index 000000000000..e9cfa7ec5420 --- /dev/null +++ b/Documentation/admin-guide/pm/intel_epb.rst @@ -0,0 +1,6 @@ +====================================== +Intel Performance and Energy Bias Hint +====================================== + +.. kernel-doc:: arch/x86/kernel/cpu/intel_epb.c + :doc: overview diff --git a/Documentation/admin-guide/pm/working-state.rst b/Documentation/admin-guide/pm/working-state.rst index b6cef9b5e961..beb004d3632b 100644 --- a/Documentation/admin-guide/pm/working-state.rst +++ b/Documentation/admin-guide/pm/working-state.rst @@ -8,3 +8,4 @@ Working-State Power Management cpuidle cpufreq intel_pstate + intel_epb diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile index cfd24f9f7614..1796d2bdcaaa 100644 --- a/arch/x86/kernel/cpu/Makefile +++ b/arch/x86/kernel/cpu/Makefile @@ -28,7 +28,7 @@ obj-y += cpuid-deps.o obj-$(CONFIG_PROC_FS) += proc.o obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o -obj-$(CONFIG_CPU_SUP_INTEL) += intel.o intel_pconfig.o +obj-$(CONFIG_CPU_SUP_INTEL) += intel.o intel_pconfig.o intel_epb.o obj-$(CONFIG_CPU_SUP_AMD) += amd.o obj-$(CONFIG_CPU_SUP_HYGON) += hygon.o obj-$(CONFIG_CPU_SUP_CYRIX_32) += cyrix.o diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index cb28e98a0659..5e37dfa4d9df 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1864,23 +1864,6 @@ void cpu_init(void) } #endif -static void bsp_resume(void) -{ - if (this_cpu->c_bsp_resume) - this_cpu->c_bsp_resume(&boot_cpu_data); -} - -static struct syscore_ops cpu_syscore_ops = { - .resume = bsp_resume, -}; - -static int __init init_cpu_syscore(void) -{ - register_syscore_ops(&cpu_syscore_ops); - return 0; -} -core_initcall(init_cpu_syscore); - /* * The microcode loader calls this upon late microcode load to recheck features, * only when microcode has been updated. Caller holds microcode_mutex and CPU diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h index 5eb946b9a9f3..c0e2407abdd6 100644 --- a/arch/x86/kernel/cpu/cpu.h +++ b/arch/x86/kernel/cpu/cpu.h @@ -14,7 +14,6 @@ struct cpu_dev { void (*c_init)(struct cpuinfo_x86 *); void (*c_identify)(struct cpuinfo_x86 *); void (*c_detect_tlb)(struct cpuinfo_x86 *); - void (*c_bsp_resume)(struct cpuinfo_x86 *); int c_x86_vendor; #ifdef CONFIG_X86_32 /* Optional vendor specific routine to obtain the cache size. */ diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index fc3c07fe7df5..f17c1a714779 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -596,36 +596,6 @@ detect_keyid_bits: c->x86_phys_bits -= keyid_bits; } -static void init_intel_energy_perf(struct cpuinfo_x86 *c) -{ - u64 epb; - - /* - * Initialize MSR_IA32_ENERGY_PERF_BIAS if not already initialized. - * (x86_energy_perf_policy(8) is available to change it at run-time.) - */ - if (!cpu_has(c, X86_FEATURE_EPB)) - return; - - rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb); - if ((epb & 0xF) != ENERGY_PERF_BIAS_PERFORMANCE) - return; - - pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n"); - pr_warn_once("ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)\n"); - epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL; - wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb); -} - -static void intel_bsp_resume(struct cpuinfo_x86 *c) -{ - /* - * MSR_IA32_ENERGY_PERF_BIAS is lost across suspend/resume, - * so reinitialize it properly like during bootup: - */ - init_intel_energy_perf(c); -} - static void init_cpuid_fault(struct cpuinfo_x86 *c) { u64 msr; @@ -763,8 +733,6 @@ static void init_intel(struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_TME)) detect_tme(c); - init_intel_energy_perf(c); - init_intel_misc_features(c); } @@ -1023,9 +991,7 @@ static const struct cpu_dev intel_cpu_dev = { .c_detect_tlb = intel_detect_tlb, .c_early_init = early_init_intel, .c_init = init_intel, - .c_bsp_resume = intel_bsp_resume, .c_x86_vendor = X86_VENDOR_INTEL, }; cpu_dev_register(intel_cpu_dev); - diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c new file mode 100644 index 000000000000..8d53cc88bd22 --- /dev/null +++ b/arch/x86/kernel/cpu/intel_epb.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Intel Performance and Energy Bias Hint support. + * + * Copyright (C) 2019 Intel Corporation + * + * Author: + * Rafael J. Wysocki <rafael.j.wysocki@intel.com> + */ + +#include <linux/cpuhotplug.h> +#include <linux/kernel.h> +#include <linux/syscore_ops.h> + +#include <asm/cpufeature.h> +#include <asm/msr.h> + +/** + * DOC: overview + * + * The Performance and Energy Bias Hint (EPB) allows software to specify its + * preference with respect to the power-performance tradeoffs present in the + * processor. Generally, the EPB is expected to be set by user space through + * the generic MSR interface (with the help of the x86_energy_perf_policy tool), + * but there are two reasons for the kernel to touch it. + * + * First, there are systems where the platform firmware resets the EPB during + * system-wide transitions from sleep states back into the working state + * effectively causing the previous EPB updates by user space to be lost. + * Thus the kernel needs to save the current EPB values for all CPUs during + * system-wide transitions to sleep states and restore them on the way back to + * the working state. That can be achieved by saving EPB for secondary CPUs + * when they are taken offline during transitions into system sleep states and + * for the boot CPU in a syscore suspend operation, so that it can be restored + * for the boot CPU in a syscore resume operation and for the other CPUs when + * they are brought back online. However, CPUs that are already offline when + * a system-wide PM transition is started are not taken offline again, but their + * EPB values may still be reset by the platform firmware during the transition, + * so in fact it is necessary to save the EPB of any CPU taken offline and to + * restore it when the given CPU goes back online at all times. + * + * Second, on many systems the initial EPB value coming from the platform + * firmware is 0 ('performance') and at least on some of them that is because + * the platform firmware does not initialize EPB at all with the assumption that + * the OS will do that anyway. That sometimes is problematic, as it may cause + * the system battery to drain too fast, for example, so it is better to adjust + * it on CPU bring-up and if the initial EPB value for a given CPU is 0, the + * kernel changes it to 6 ('normal'). + */ + +static DEFINE_PER_CPU(u8, saved_epb); + +#define EPB_MASK 0x0fULL +#define EPB_SAVED 0x10ULL + +static int intel_epb_save(void) +{ + u64 epb; + + rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb); + /* + * Ensure that saved_epb will always be nonzero after this write even if + * the EPB value read from the MSR is 0. + */ + this_cpu_write(saved_epb, (epb & EPB_MASK) | EPB_SAVED); + + return 0; +} + +static void intel_epb_restore(void) +{ + u64 val = this_cpu_read(saved_epb); + u64 epb; + + rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb); + if (val) { + val &= EPB_MASK; + } else { + /* + * Because intel_epb_save() has not run for the current CPU yet, + * it is going online for the first time, so if its EPB value is + * 0 ('performance') at this point, assume that it has not been + * initialized by the platform firmware and set it to 6 + * ('normal'). + */ + val = epb & EPB_MASK; + if (val == ENERGY_PERF_BIAS_PERFORMANCE) { + val = ENERGY_PERF_BIAS_NORMAL; + pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n"); + } + } + wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, (epb & ~EPB_MASK) | val); +} + +static struct syscore_ops intel_epb_syscore_ops = { + .suspend = intel_epb_save, + .resume = intel_epb_restore, +}; + +static int intel_epb_online(unsigned int cpu) +{ + intel_epb_restore(); + return 0; +} + +static int intel_epb_offline(unsigned int cpu) +{ + return intel_epb_save(); +} + +static __init int intel_epb_init(void) +{ + int ret; + + if (!boot_cpu_has(X86_FEATURE_EPB)) + return -ENODEV; + + ret = cpuhp_setup_state(CPUHP_AP_X86_INTEL_EPB_ONLINE, + "x86/intel/epb:online", intel_epb_online, + intel_epb_offline); + if (ret < 0) + goto err_out_online; + + register_syscore_ops(&intel_epb_syscore_ops); + return 0; + +err_out_online: + cpuhp_remove_state(CPUHP_AP_X86_INTEL_EPB_ONLINE); + return ret; +} +subsys_initcall(intel_epb_init); diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index e78281d07b70..dbfdd0fadbef 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -147,6 +147,7 @@ enum cpuhp_state { CPUHP_AP_X86_VDSO_VMA_ONLINE, CPUHP_AP_IRQ_AFFINITY_ONLINE, CPUHP_AP_ARM_MVEBU_SYNC_CLOCKS, + CPUHP_AP_X86_INTEL_EPB_ONLINE, CPUHP_AP_PERF_ONLINE, CPUHP_AP_PERF_X86_ONLINE, CPUHP_AP_PERF_X86_UNCORE_ONLINE, |