s390/cpumsf: Check for CPU Measurement sampling

s390 IBM z15 introduces a check if the CPU Mesurement Facility
sampling is temporarily unavailable. If this is the case return -EBUSY
and abort the setup of CPU Measuement facility sampling.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/include/asm/cpu_mf.h b/arch/s390/include/asm/cpu_mf.h
index ceeb552d34729497418238bb8f27b0193dede941..753669bfbe99d9a34d237942448223c464281f30 100644 (file)
--- a/arch/s390/include/asm/cpu_mf.h
+++ b/arch/s390/include/asm/cpu_mf.h
@@ -28,6 +28,8 @@ asm(".include \"asm/cpu_mf-insn.h\"\n");
                                 CPU_MF_INT_SF_PRA|CPU_MF_INT_SF_SACA|  \
                                 CPU_MF_INT_SF_LSDA)
 
+#define CPU_MF_SF_RIBM_NOTAV   0x1             /* Sampling unavailable */
+
 /* CPU measurement facility support */
 static inline int cpum_cf_avail(void)
 {
@@ -69,7 +71,8 @@ struct hws_qsi_info_block {       /* Bit(s) */
        unsigned long max_sampl_rate; /* 16-23: maximum sampling interval*/
        unsigned long tear;         /* 24-31: TEAR contents              */
        unsigned long dear;         /* 32-39: DEAR contents              */
-       unsigned int rsvrd0;        /* 40-43: reserved                   */
+       unsigned int rsvrd0:24;     /* 40-42: reserved                   */
+       unsigned int ribm:8;        /* 43: Reserved by IBM               */
        unsigned int cpu_speed;     /* 44-47: CPU speed                  */
        unsigned long long rsvrd1;  /* 48-55: reserved                   */
        unsigned long long rsvrd2;  /* 56-63: reserved                   */

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 544a02e944c65156aca41c4b8edffe2882862bfb..2421f0b62630aa4b333cc7c446f621568253d897 100644 (file)
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -803,6 +803,12 @@ static int __hw_perf_event_init(struct perf_event *event)
                goto out;
        }
 
+       if (si.ribm & CPU_MF_SF_RIBM_NOTAV) {
+               pr_warn("CPU Measurement Facility sampling is temporarily not available\n");
+               err = -EBUSY;
+               goto out;
+       }
+
        /* Always enable basic sampling */
        SAMPL_FLAGS(hwc) = PERF_CPUM_SF_BASIC_MODE;