[kvm-unit-tests PATCH v4 20/24] x86/pmu: Add global helpers to cover Intel Arch PMU Version 1

[Like Xu <like.xu.linux@xxxxxxxxx>]

From: Like Xu <likexu@xxxxxxxxxxx>

To test Intel arch pmu version 1, most of the basic framework and
use cases which test any PMU counter do not require any changes,
except no access to registers introduced only in PMU version 2.

Adding some guardian's checks can seamlessly support version 1,
while opening the door for normal AMD PMUs tests.

Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
---
 lib/x86/pmu.c |  8 +++++---
 lib/x86/pmu.h |  5 +++++
 x86/pmu.c     | 47 +++++++++++++++++++++++++++++++----------------
 3 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/lib/x86/pmu.c b/lib/x86/pmu.c
index 3b6be37..43e6a43 100644
--- a/lib/x86/pmu.c
+++ b/lib/x86/pmu.c
@@ -10,8 +10,10 @@ void pmu_init(void)
         pmu.perf_cap = rdmsr(MSR_IA32_PERF_CAPABILITIES);
     pmu.msr_gp_counter_base = MSR_IA32_PERFCTR0;
     pmu.msr_gp_event_select_base = MSR_P6_EVNTSEL0;
-    pmu.msr_global_status = MSR_CORE_PERF_GLOBAL_STATUS;
-    pmu.msr_global_ctl = MSR_CORE_PERF_GLOBAL_CTRL;
-    pmu.msr_global_status_clr = MSR_CORE_PERF_GLOBAL_OVF_CTRL;
+    if (this_cpu_support_perf_status()) {
+        pmu.msr_global_status = MSR_CORE_PERF_GLOBAL_STATUS;
+        pmu.msr_global_ctl = MSR_CORE_PERF_GLOBAL_CTRL;
+        pmu.msr_global_status_clr = MSR_CORE_PERF_GLOBAL_OVF_CTRL;
+    }
     reset_all_counters();
 }
\ No newline at end of file
diff --git a/lib/x86/pmu.h b/lib/x86/pmu.h
index 9ba2419..fa49a8f 100644
--- a/lib/x86/pmu.h
+++ b/lib/x86/pmu.h
@@ -116,6 +116,11 @@ static inline bool this_cpu_has_perf_global_ctrl(void)
 	return pmu_version() > 1;
 }
 
+static inline bool this_cpu_support_perf_status(void)
+{
+	return pmu_version() > 1;
+}
+
 static inline u8 pmu_nr_gp_counters(void)
 {
 	return (cpuid_10.a >> 8) & 0xff;
diff --git a/x86/pmu.c b/x86/pmu.c
index 015591f..daeb7a2 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -102,12 +102,18 @@ static struct pmu_event* get_counter_event(pmu_counter_t *cnt)
 
 static void global_enable(pmu_counter_t *cnt)
 {
+	if (!this_cpu_has_perf_global_ctrl())
+		return;
+
 	cnt->idx = event_to_global_idx(cnt);
 	pmu_set_global_enable(pmu_get_global_enable() | BIT_ULL(cnt->idx));
 }
 
 static void global_disable(pmu_counter_t *cnt)
 {
+	if (!this_cpu_has_perf_global_ctrl())
+		return;
+
 	pmu_set_global_enable(pmu_get_global_enable() & ~BIT_ULL(cnt->idx));
 }
 
@@ -286,7 +292,8 @@ static void check_counter_overflow(void)
 	overflow_preset = measure_for_overflow(&cnt);
 
 	/* clear status before test */
-	pmu_clear_global_status();
+	if (this_cpu_support_perf_status())
+		pmu_clear_global_status();
 
 	report_prefix_push("overflow");
 
@@ -313,6 +320,10 @@ static void check_counter_overflow(void)
 		idx = event_to_global_idx(&cnt);
 		__measure(&cnt, cnt.count);
 		report(cnt.count == 1, "cntr-%d", i);
+
+		if (!this_cpu_support_perf_status())
+			continue;
+
 		status = pmu_get_global_status();
 		report(status & (1ull << idx), "status-%d", i);
 		pmu_ack_global_status(status);
@@ -425,7 +436,8 @@ static void check_running_counter_wrmsr(void)
 	report(evt.count < gp_events[1].min, "cntr");
 
 	/* clear status before overflow test */
-	pmu_clear_global_status();
+	if (this_cpu_support_perf_status())
+		pmu_clear_global_status();
 
 	start_event(&evt);
 
@@ -437,8 +449,11 @@ static void check_running_counter_wrmsr(void)
 
 	loop();
 	stop_event(&evt);
-	status = pmu_get_global_status();
-	report(status & 1, "status msr bit");
+
+	if (this_cpu_support_perf_status()) {
+		status = pmu_get_global_status();
+		report(status & 1, "status msr bit");
+	}
 
 	report_prefix_pop();
 }
@@ -458,7 +473,8 @@ static void check_emulated_instr(void)
 	};
 	report_prefix_push("emulated instruction");
 
-	pmu_clear_global_status();
+	if (this_cpu_support_perf_status())
+		pmu_clear_global_status();
 
 	start_event(&brnch_cnt);
 	start_event(&instr_cnt);
@@ -492,7 +508,8 @@ static void check_emulated_instr(void)
 		:
 		: "eax", "ebx", "ecx", "edx");
 
-	pmu_reset_global_enable();
+	if (this_cpu_has_perf_global_ctrl())
+		pmu_reset_global_enable();
 
 	stop_event(&brnch_cnt);
 	stop_event(&instr_cnt);
@@ -503,10 +520,12 @@ static void check_emulated_instr(void)
 	       "instruction count");
 	report(brnch_cnt.count - brnch_start >= EXPECTED_BRNCH,
 	       "branch count");
-	// Additionally check that those counters overflowed properly.
-	status = pmu_get_global_status();
-	report(status & 1, "branch counter overflow");
-	report(status & 2, "instruction counter overflow");
+	if (this_cpu_support_perf_status()) {
+		// Additionally check that those counters overflowed properly.
+		status = pmu_get_global_status();
+		report(status & 1, "branch counter overflow");
+		report(status & 2, "instruction counter overflow");
+	}
 
 	report_prefix_pop();
 }
@@ -593,7 +612,8 @@ static void set_ref_cycle_expectations(void)
 	if (!pmu_nr_gp_counters() || !pmu_gp_counter_is_available(2))
 		return;
 
-	pmu_reset_global_enable();
+	if (this_cpu_has_perf_global_ctrl())
+		pmu_reset_global_enable();
 
 	t0 = fenced_rdtsc();
 	start_event(&cnt);
@@ -644,11 +664,6 @@ int main(int ac, char **av)
 		return report_summary();
 	}
 
-	if (pmu_version() == 1) {
-		report_skip("PMU version 1 is not supported.");
-		return report_summary();
-	}
-
 	set_ref_cycle_expectations();
 
 	printf("PMU version:         %d\n", pmu_version());
-- 
2.38.1