diff options
Diffstat (limited to 'arch/x86/kernel/tsc_sync.c')
| -rw-r--r-- | arch/x86/kernel/tsc_sync.c | 108 |
1 files changed, 71 insertions, 37 deletions
diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c index 50a4515fe0ad..ec3aa340d351 100644 --- a/arch/x86/kernel/tsc_sync.c +++ b/arch/x86/kernel/tsc_sync.c @@ -15,11 +15,13 @@ * ( The serial nature of the boot logic and the CPU hotplug lock * protects against more than 2 CPUs entering this code. ) */ +#include <linux/workqueue.h> #include <linux/topology.h> #include <linux/spinlock.h> #include <linux/kernel.h> #include <linux/smp.h> #include <linux/nmi.h> +#include <asm/msr.h> #include <asm/tsc.h> struct tsc_adjust { @@ -30,6 +32,7 @@ struct tsc_adjust { }; static DEFINE_PER_CPU(struct tsc_adjust, tsc_adjust); +static struct timer_list tsc_sync_check_timer; /* * TSC's on different sockets may be reset asynchronously. @@ -63,12 +66,12 @@ void tsc_verify_tsc_adjust(bool resume) adj->nextcheck = jiffies + HZ; - rdmsrl(MSR_IA32_TSC_ADJUST, curval); + rdmsrq(MSR_IA32_TSC_ADJUST, curval); if (adj->adjusted == curval) return; /* Restore the original value */ - wrmsrl(MSR_IA32_TSC_ADJUST, adj->adjusted); + wrmsrq(MSR_IA32_TSC_ADJUST, adj->adjusted); if (!adj->warned || resume) { pr_warn(FW_BUG "TSC ADJUST differs: CPU%u %lld --> %lld. Restoring\n", @@ -77,6 +80,46 @@ void tsc_verify_tsc_adjust(bool resume) } } +/* + * Normally the tsc_sync will be checked every time system enters idle + * state, but there is still caveat that a system won't enter idle, + * either because it's too busy or configured purposely to not enter + * idle. + * + * So setup a periodic timer (every 10 minutes) to make sure the check + * is always on. + */ + +#define SYNC_CHECK_INTERVAL (HZ * 600) + +static void tsc_sync_check_timer_fn(struct timer_list *unused) +{ + int next_cpu; + + tsc_verify_tsc_adjust(false); + + /* Run the check for all onlined CPUs in turn */ + next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); + if (next_cpu >= nr_cpu_ids) + next_cpu = cpumask_first(cpu_online_mask); + + tsc_sync_check_timer.expires += SYNC_CHECK_INTERVAL; + add_timer_on(&tsc_sync_check_timer, next_cpu); +} + +static int __init start_sync_check_timer(void) +{ + if (!cpu_feature_enabled(X86_FEATURE_TSC_ADJUST) || tsc_clocksource_reliable) + return 0; + + timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn, 0); + tsc_sync_check_timer.expires = jiffies + SYNC_CHECK_INTERVAL; + add_timer(&tsc_sync_check_timer); + + return 0; +} +late_initcall(start_sync_check_timer); + static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval, unsigned int cpu, bool bootcpu) { @@ -100,7 +143,7 @@ static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval, if (likely(!tsc_async_resets)) { pr_warn(FW_BUG "TSC ADJUST: CPU%u: %lld force to 0\n", cpu, bootval); - wrmsrl(MSR_IA32_TSC_ADJUST, 0); + wrmsrq(MSR_IA32_TSC_ADJUST, 0); bootval = 0; } else { pr_info("TSC ADJUST: CPU%u: %lld NOT forced to 0\n", @@ -123,7 +166,7 @@ bool __init tsc_store_and_check_tsc_adjust(bool bootcpu) if (check_tsc_unstable()) return false; - rdmsrl(MSR_IA32_TSC_ADJUST, bootval); + rdmsrq(MSR_IA32_TSC_ADJUST, bootval); cur->bootval = bootval; cur->nextcheck = jiffies + HZ; tsc_sanitize_first_cpu(cur, bootval, smp_processor_id(), bootcpu); @@ -145,17 +188,15 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu) if (!boot_cpu_has(X86_FEATURE_TSC_ADJUST)) return false; - rdmsrl(MSR_IA32_TSC_ADJUST, bootval); + rdmsrq(MSR_IA32_TSC_ADJUST, bootval); cur->bootval = bootval; cur->nextcheck = jiffies + HZ; cur->warned = false; /* - * If a non-zero TSC value for socket 0 may be valid then the default - * adjusted value cannot assumed to be zero either. + * The default adjust value cannot be assumed to be zero on any socket. */ - if (tsc_async_resets) - cur->adjusted = bootval; + cur->adjusted = bootval; /* * Check whether this CPU is the first in a package to come up. In @@ -189,7 +230,7 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu) */ if (bootval != ref->adjusted) { cur->adjusted = ref->adjusted; - wrmsrl(MSR_IA32_TSC_ADJUST, ref->adjusted); + wrmsrq(MSR_IA32_TSC_ADJUST, ref->adjusted); } /* * We have the TSCs forced to be in sync on this package. Skip sync @@ -204,7 +245,6 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu) */ static atomic_t start_count; static atomic_t stop_count; -static atomic_t skip_test; static atomic_t test_runs; /* @@ -302,22 +342,22 @@ static inline unsigned int loop_timeout(int cpu) return (cpumask_weight(topology_core_cpumask(cpu)) > 1) ? 2 : 20; } +static void tsc_sync_mark_tsc_unstable(struct work_struct *work) +{ + mark_tsc_unstable("check_tsc_sync_source failed"); +} + +static DECLARE_WORK(tsc_sync_work, tsc_sync_mark_tsc_unstable); + /* - * Source CPU calls into this - it waits for the freshly booted - * target CPU to arrive and then starts the measurement: + * The freshly booted CPU initiates this via an async SMP function call. */ -void check_tsc_sync_source(int cpu) +static void check_tsc_sync_source(void *__cpu) { + unsigned int cpu = (unsigned long)__cpu; int cpus = 2; /* - * No need to check if we already know that the TSC is not - * synchronized or if we have no TSC. - */ - if (unsynchronized_tsc()) - return; - - /* * Set the maximum number of test runs to * 1 if the CPU does not provide the TSC_ADJUST MSR * 3 if the MSR is available, so the target can try to adjust @@ -327,16 +367,9 @@ void check_tsc_sync_source(int cpu) else atomic_set(&test_runs, 3); retry: - /* - * Wait for the target to start or to skip the test: - */ - while (atomic_read(&start_count) != cpus - 1) { - if (atomic_read(&skip_test) > 0) { - atomic_set(&skip_test, 0); - return; - } + /* Wait for the target to start. */ + while (atomic_read(&start_count) != cpus - 1) cpu_relax(); - } /* * Trigger the target to continue into the measurement too: @@ -356,20 +389,20 @@ retry: if (!nr_warps) { atomic_set(&test_runs, 0); - pr_debug("TSC synchronization [CPU#%d -> CPU#%d]: passed\n", + pr_debug("TSC synchronization [CPU#%d -> CPU#%u]: passed\n", smp_processor_id(), cpu); } else if (atomic_dec_and_test(&test_runs) || random_warps) { /* Force it to 0 if random warps brought us here */ atomic_set(&test_runs, 0); - pr_warn("TSC synchronization [CPU#%d -> CPU#%d]:\n", + pr_warn("TSC synchronization [CPU#%d -> CPU#%u]:\n", smp_processor_id(), cpu); pr_warn("Measured %Ld cycles TSC warp between CPUs, " "turning off TSC clock.\n", max_warp); if (random_warps) pr_warn("TSC warped randomly between CPUs\n"); - mark_tsc_unstable("check_tsc_sync_source failed"); + schedule_work(&tsc_sync_work); } /* @@ -416,11 +449,12 @@ void check_tsc_sync_target(void) * SoCs the TSC is frequency synchronized, but still the TSC ADJUST * register might have been wreckaged by the BIOS.. */ - if (tsc_store_and_check_tsc_adjust(false) || tsc_clocksource_reliable) { - atomic_inc(&skip_test); + if (tsc_store_and_check_tsc_adjust(false) || tsc_clocksource_reliable) return; - } + /* Kick the control CPU into the TSC synchronization function */ + smp_call_function_single(cpumask_first(cpu_online_mask), check_tsc_sync_source, + (unsigned long *)(unsigned long)cpu, 0); retry: /* * Register this CPU's participation and wait for the @@ -485,7 +519,7 @@ retry: pr_warn("TSC ADJUST compensate: CPU%u observed %lld warp. Adjust: %lld\n", cpu, cur_max_warp, cur->adjusted); - wrmsrl(MSR_IA32_TSC_ADJUST, cur->adjusted); + wrmsrq(MSR_IA32_TSC_ADJUST, cur->adjusted); goto retry; } |