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Date: Sun, 5 Aug 2012 23:26:32 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Andre Przywara <andre.przywara@....com>,
Len Brown <lenb@...nel.org>, Dave Jones <davej@...hat.com>
Cc: cpufreq@...r.kernel.org, Matthew Garrett <mjg@...hat.com>,
Andreas Herrmann <andreas.herrmann3@....com>,
Thomas Renninger <trenn@...e.de>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/8] acpi-cpufreq: Add support for disabling dynamic overclocking
On Thursday, July 26, 2012, Andre Przywara wrote:
> One feature present in powernow-k8 that isn't present in acpi-cpufreq
> is support for enabling or disabling AMD's core performance boost
> technology. This patch adds support to acpi-cpufreq, but also
> includes support for Intel's dynamic acceleration.
>
> The original boost disabling sysfs file was per CPU, but acted
> globally. Also the naming (cpb) was at least not intuitive.
> So lets introduce a single file simply called "boost", which sits
> once in /sys/devices/system/cpu/cpufreq. This should be the
> documented and approved way of using this feature.
>
> A following patch will re-introduce the cpb knob for compatibility
> reasons on AMD CPUs.
>
> Per-CPU boost switching is possible, but not trivial and is thus
> postponed to a later patch series.
>
> Signed-off-by: Andre Przywara <andre.przywara@....com>
Len, Dave, any comments and/or objections here?
Rafael
> ---
> drivers/cpufreq/acpi-cpufreq.c | 177 ++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 177 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index ea949b8..ca41aaa 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -61,6 +61,8 @@ enum {
> #define INTEL_MSR_RANGE (0xffff)
> #define AMD_MSR_RANGE (0x7)
>
> +#define MSR_K7_HWCR_CPB_DIS (1ULL << 25)
> +
> struct acpi_cpufreq_data {
> struct acpi_processor_performance *acpi_data;
> struct cpufreq_frequency_table *freq_table;
> @@ -76,6 +78,96 @@ static struct acpi_processor_performance __percpu *acpi_perf_data;
> static struct cpufreq_driver acpi_cpufreq_driver;
>
> static unsigned int acpi_pstate_strict;
> +static bool boost_enabled, boost_supported;
> +static struct msr __percpu *msrs;
> +
> +static bool boost_state(unsigned int cpu)
> +{
> + u32 lo, hi;
> + u64 msr;
> +
> + switch (boot_cpu_data.x86_vendor) {
> + case X86_VENDOR_INTEL:
> + rdmsr_on_cpu(cpu, MSR_IA32_MISC_ENABLE, &lo, &hi);
> + msr = lo | ((u64)hi << 32);
> + return !(msr & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
> + case X86_VENDOR_AMD:
> + rdmsr_on_cpu(cpu, MSR_K7_HWCR, &lo, &hi);
> + msr = lo | ((u64)hi << 32);
> + return !(msr & MSR_K7_HWCR_CPB_DIS);
> + }
> + return false;
> +}
> +
> +static void boost_set_msrs(bool enable, const struct cpumask *cpumask)
> +{
> + u32 cpu;
> + u32 msr_addr;
> + u64 msr_mask;
> +
> + switch (boot_cpu_data.x86_vendor) {
> + case X86_VENDOR_INTEL:
> + msr_addr = MSR_IA32_MISC_ENABLE;
> + msr_mask = MSR_IA32_MISC_ENABLE_TURBO_DISABLE;
> + break;
> + case X86_VENDOR_AMD:
> + msr_addr = MSR_K7_HWCR;
> + msr_mask = MSR_K7_HWCR_CPB_DIS;
> + break;
> + default:
> + return;
> + }
> +
> + rdmsr_on_cpus(cpumask, msr_addr, msrs);
> +
> + for_each_cpu(cpu, cpumask) {
> + struct msr *reg = per_cpu_ptr(msrs, cpu);
> + if (enable)
> + reg->q &= ~msr_mask;
> + else
> + reg->q |= msr_mask;
> + }
> +
> + wrmsr_on_cpus(cpumask, msr_addr, msrs);
> +}
> +
> +static ssize_t store_global_boost(struct kobject *kobj, struct attribute *attr,
> + const char *buf, size_t count)
> +{
> + int ret;
> + unsigned long val = 0;
> +
> + if (!boost_supported)
> + return -EINVAL;
> +
> + ret = kstrtoul(buf, 10, &val);
> + if (ret || (val > 1))
> + return -EINVAL;
> +
> + if ((val && boost_enabled) || (!val && !boost_enabled))
> + return count;
> +
> + get_online_cpus();
> +
> + boost_set_msrs(val, cpu_online_mask);
> +
> + put_online_cpus();
> +
> + boost_enabled = val;
> + pr_debug("Core Boosting %sabled.\n", val ? "en" : "dis");
> +
> + return count;
> +}
> +
> +static ssize_t show_global_boost(struct kobject *kobj,
> + struct attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%u\n", boost_enabled);
> +}
> +
> +static struct global_attr global_boost = __ATTR(boost, 0644,
> + show_global_boost,
> + store_global_boost);
>
> static int check_est_cpu(unsigned int cpuid)
> {
> @@ -446,6 +538,44 @@ static void free_acpi_perf_data(void)
> free_percpu(acpi_perf_data);
> }
>
> +static int boost_notify(struct notifier_block *nb, unsigned long action,
> + void *hcpu)
> +{
> + unsigned cpu = (long)hcpu;
> + const struct cpumask *cpumask;
> +
> + cpumask = get_cpu_mask(cpu);
> +
> + /*
> + * Clear the boost-disable bit on the CPU_DOWN path so that
> + * this cpu cannot block the remaining ones from boosting. On
> + * the CPU_UP path we simply keep the boost-disable flag in
> + * sync with the current global state.
> + */
> +
> + switch (action) {
> + case CPU_UP_PREPARE:
> + case CPU_UP_PREPARE_FROZEN:
> + boost_set_msrs(boost_enabled, cpumask);
> + break;
> +
> + case CPU_DOWN_PREPARE:
> + case CPU_DOWN_PREPARE_FROZEN:
> + boost_set_msrs(1, cpumask);
> + break;
> +
> + default:
> + break;
> + }
> +
> + return NOTIFY_OK;
> +}
> +
> +
> +static struct notifier_block boost_nb = {
> + .notifier_call = boost_notify,
> +};
> +
> /*
> * acpi_cpufreq_early_init - initialize ACPI P-States library
> *
> @@ -772,6 +902,49 @@ static struct cpufreq_driver acpi_cpufreq_driver = {
> .attr = acpi_cpufreq_attr,
> };
>
> +static void __init acpi_cpufreq_boost_init(void)
> +{
> + if (boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA)) {
> + msrs = msrs_alloc();
> +
> + if (!msrs)
> + return;
> +
> + boost_supported = true;
> + boost_enabled = boost_state(0);
> +
> + get_online_cpus();
> +
> + /* Force all MSRs to the same value */
> + boost_set_msrs(boost_enabled, cpu_online_mask);
> +
> + register_cpu_notifier(&boost_nb);
> +
> + put_online_cpus();
> + } else
> + global_boost.attr.mode = 0444;
> +
> + /* We create the boost file in any case, though for systems without
> + * hardware support it will be read-only and hardwired to return 0.
> + */
> + if (sysfs_create_file(cpufreq_global_kobject, &(global_boost.attr)))
> + pr_warn("could not register global boost sysfs file\n");
> + else
> + pr_debug("registered global boost sysfs file\n");
> +}
> +
> +static void __exit acpi_cpufreq_boost_exit(void)
> +{
> + sysfs_remove_file(cpufreq_global_kobject, &(global_boost.attr));
> +
> + if (msrs) {
> + unregister_cpu_notifier(&boost_nb);
> +
> + msrs_free(msrs);
> + msrs = NULL;
> + }
> +}
> +
> static int __init acpi_cpufreq_init(void)
> {
> int ret;
> @@ -789,6 +962,8 @@ static int __init acpi_cpufreq_init(void)
> if (ret)
> free_acpi_perf_data();
>
> + acpi_cpufreq_boost_init();
> +
> return ret;
> }
>
> @@ -796,6 +971,8 @@ static void __exit acpi_cpufreq_exit(void)
> {
> pr_debug("acpi_cpufreq_exit\n");
>
> + acpi_cpufreq_boost_exit();
> +
> cpufreq_unregister_driver(&acpi_cpufreq_driver);
>
> free_acpi_perf_data();
>
--
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