s390/cpum_cf: introduce kernel_cpumcf_avail() function

A preparation to move out common CPU-MF counter facility support
functions, first introduce a function that indicates whether the
support is ready to use.

Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/include/asm/cpu_mcf.h b/arch/s390/include/asm/cpu_mcf.h
index 12a4224..7121365 100644 (file)
--- a/arch/s390/include/asm/cpu_mcf.h
+++ b/arch/s390/include/asm/cpu_mcf.h
@@ -59,6 +59,7 @@ struct cpu_cf_events {
 };
 DECLARE_PER_CPU(struct cpu_cf_events, cpu_cf_events);
 
+bool kernel_cpumcf_avail(void);
 int __kernel_cpumcf_begin(void);
 unsigned long kernel_cpumcf_alert(int clear);
 void __kernel_cpumcf_end(void);

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index c05f691..ab4b8c9 100644 (file)
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -33,6 +33,9 @@ DEFINE_PER_CPU(struct cpu_cf_events, cpu_cf_events) = {
        .txn_flags = 0,
 };
 
+/* Indicator whether the CPU-Measurement Counter Facility Support is ready */
+static bool cpum_cf_initalized;
+
 static enum cpumf_ctr_set get_counter_set(u64 event)
 {
        int set = CPUMF_CTR_SET_MAX;
@@ -233,6 +236,12 @@ static void setup_pmc_cpu(void *flags)
        lcctl(0);
 }
 
+bool kernel_cpumcf_avail(void)
+{
+       return cpum_cf_initalized;
+}
+EXPORT_SYMBOL(kernel_cpumcf_avail);
+
 /* Reserve/release functions for sharing perf hardware */
 static DEFINE_SPINLOCK(cpumcf_owner_lock);
 static void *cpumcf_owner;
@@ -709,8 +718,13 @@ static int __init cpumf_pmu_init(void)
                                        cpumf_measurement_alert);
                return rc;
        }
-       return cpuhp_setup_state(CPUHP_AP_PERF_S390_CF_ONLINE,
-                                "perf/s390/cf:online",
-                                s390_pmu_online_cpu, s390_pmu_offline_cpu);
+
+       rc = cpuhp_setup_state(CPUHP_AP_PERF_S390_CF_ONLINE,
+                               "perf/s390/cf:online",
+                               s390_pmu_online_cpu, s390_pmu_offline_cpu);
+       if (!rc)
+               cpum_cf_initalized = true;
+
+       return rc;
 }
 early_initcall(cpumf_pmu_init);