[SRU][B][D][E][Patch 1/1] s390/cpumsf: Check for CPU Measurement sampling

[frank.heimes at canonical.com]

From: Thomas Richter <tmricht at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1847590

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 at linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger at de.ibm.com>
Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>
(cherry picked from commit 932bfc5aae08f3cb20c1c9f051542f5933710151)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 arch/s390/include/asm/cpu_mf.h  | 7 +++++--
 arch/s390/kernel/perf_cpum_sf.c | 6 ++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/cpu_mf.h b/arch/s390/include/asm/cpu_mf.h
index 4082542..55f9e92 100644
--- a/arch/s390/include/asm/cpu_mf.h
+++ b/arch/s390/include/asm/cpu_mf.h
@@ -26,6 +26,8 @@
 				 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)
 {
@@ -67,8 +69,9 @@ 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 cpu_speed;     /* 44-47: CPU speed 		 */
+	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			 */
 } __packed;
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 2d55fc2..9cde67e 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -728,6 +728,12 @@ 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;
 
-- 
2.7.4