[kvm-unit-tests RFC 04/10] pmu: Check Required Event Support

[Eric Auger <eric.auger@redhat.com>]

If event counters are implemented check the common events
required by the PMUv3 are implemented.

Some are unconditionally required (SW_INCR, CPU_CYCLES,
either INST_RETIRED or INST_SPEC). Some others only are
required if the implementation implements some other features.

Check those wich are unconditionally required.

This test currently fails on TCG as neither INST_RETIRED
or INST_SPEC are supported.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 arm/pmu.c         | 70 +++++++++++++++++++++++++++++++++++++++++++++++
 arm/unittests.cfg |  6 ++++
 2 files changed, 76 insertions(+)

diff --git a/arm/pmu.c b/arm/pmu.c
index 8e95251..f78c43f 100644
--- a/arm/pmu.c
+++ b/arm/pmu.c
@@ -102,6 +102,10 @@ static inline void precise_instrs_loop(int loop, uint32_t pmcr)
 	: [pmcr] "r" (pmcr), [z] "r" (0)
 	: "cc");
 }
+
+/* event counter tests only implemented for aarch64 */
+static void test_event_introspection(void) {}
+
 #elif defined(__aarch64__)
 #define ID_AA64DFR0_PERFMON_SHIFT 8
 #define ID_AA64DFR0_PERFMON_MASK  0xf
@@ -140,6 +144,69 @@ static inline void precise_instrs_loop(int loop, uint32_t pmcr)
 	: [pmcr] "r" (pmcr)
 	: "cc");
 }
+
+#define PMCEID1_EL0 sys_reg(11, 3, 9, 12, 7)
+
+static bool is_event_supported(uint32_t n, bool warn)
+{
+	uint64_t pmceid0 = read_sysreg(pmceid0_el0);
+	uint64_t pmceid1 = read_sysreg_s(PMCEID1_EL0);
+	bool supported;
+	uint32_t reg;
+
+	if (n >= 0x0  && n <= 0x1F) {
+		reg = pmceid0 & 0xFFFFFFFF;
+	} else if  (n >= 0x4000 && n <= 0x401F) {
+		reg = pmceid0 >> 32;
+	} else if (n >= 0x20  && n <= 0x3F) {
+		reg = pmceid1 & 0xFFFFFFFF;
+	} else if (n >= 0x4020 && n <= 0x403F) {
+		reg = pmceid1 >> 32;
+	} else {
+		abort();
+	}
+	supported =  reg & (1 << n);
+	if (!supported && warn)
+		report_info("event %d is not supported", n);
+	return supported;
+}
+
+static void test_event_introspection(void)
+{
+	bool required_events;
+
+	if (!pmu.nb_implemented_counters) {
+		report_skip("No event counter, skip ...");
+		return;
+	}
+	if (pmu.nb_implemented_counters < 2)
+		report_info("%d event counters are implemented. "
+                            "ARM recommends to implement at least 2",
+                            pmu.nb_implemented_counters);
+
+	/* PMUv3 requires an implementation includes some common events */
+	required_events = is_event_supported(0x0, true) /* SW_INCR */ &&
+			  is_event_supported(0x11, true) /* CPU_CYCLES */ &&
+			  (is_event_supported(0x8, true) /* INST_RETIRED */ ||
+			   is_event_supported(0x1B, true) /* INST_PREC */);
+	if (!is_event_supported(0x8, false))
+		report_info("ARM strongly recomments INST_RETIRED (0x8) event "
+			    "to be implemented");
+
+	if (pmu.version == 0x4) {
+		/* ARMv8.1 PMU: STALL_FRONTEND and STALL_BACKEND are required */
+		required_events = required_events ||
+				  is_event_supported(0x23, true) ||
+				  is_event_supported(0x24, true);
+	}
+
+	/* L1D_CACHE_REFILL(0x3) and L1D_CACHE(0x4) are only required if
+	   L1 data / unified cache. BR_MIS_PRED(0x10), BR_PRED(0x12) are only
+	   required if program-flow prediction is implemented. */
+
+	report("Check required events are implemented", required_events);
+}
+
 #endif
 
 /*
@@ -324,6 +391,9 @@ int main(int argc, char *argv[])
 		report("Monotonically increasing cycle count", check_cycles_increase());
 		report("Cycle/instruction ratio", check_cpi(cpi));
 		pmccntr64_test();
+	} else if (strcmp(argv[1], "event-introspection") == 0) {
+		report_prefix_push(argv[1]);
+		test_event_introspection();
 	} else {
 		report_abort("Unknown subtest '%s'", argv[1]);
 	}
diff --git a/arm/unittests.cfg b/arm/unittests.cfg
index 79f0d7a..4433ef3 100644
--- a/arm/unittests.cfg
+++ b/arm/unittests.cfg
@@ -66,6 +66,12 @@ file = pmu.flat
 groups = pmu
 extra_params = -append 'cycle-counter 0'
 
+[pmu-event-introspection]
+file = pmu.flat
+groups = pmu
+arch = arm64
+extra_params = -append 'event-introspection'
+
 # Test PMU support (TCG) with -icount IPC=1
 #[pmu-tcg-icount-1]
 #file = pmu.flat
-- 
2.20.1