Run a basic test to ensure we can write an arbitrary value to the core
counters and read it back.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
---
 .../selftests/kvm/x86_64/pmu_counters_test.c  | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
index 5b240585edc5..79ca7d608e00 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -641,11 +641,65 @@ static uint8_t nr_core_counters(void)
 		return AMD_NR_CORE_EXT_COUNTERS;
 
 	return AMD_NR_CORE_COUNTERS;
+}
+
+static uint8_t guest_nr_core_counters(void)
+{
+	uint8_t nr_counters = this_cpu_property(X86_PROPERTY_NUM_PERF_CTR_CORE);
+	bool core_ext = this_cpu_has(X86_FEATURE_PERF_CTR_EXT_CORE);
+
+	if (nr_counters != 0)
+		return nr_counters;
+
+	if (core_ext)
+		return AMD_NR_CORE_EXT_COUNTERS;
+
+	return AMD_NR_CORE_COUNTERS;
+
+}
 
+static void guest_test_rdwr_core_counters(void)
+{
+	bool core_ext = this_cpu_has(X86_FEATURE_PERF_CTR_EXT_CORE);
+	uint8_t nr_counters = guest_nr_core_counters();
+	uint8_t i;
+	uint32_t esel_msr_base = core_ext ? MSR_F15H_PERF_CTL : MSR_K7_EVNTSEL0;
+	uint32_t cnt_msr_base = core_ext ? MSR_F15H_PERF_CTR : MSR_K7_PERFCTR0;
+	uint32_t msr_step = core_ext ? 2 : 1;
+
+	for (i = 0; i < AMD_NR_CORE_EXT_COUNTERS; i++) {
+		uint64_t test_val = 0xffff;
+		uint32_t esel_msr = esel_msr_base + msr_step * i;
+		uint32_t cnt_msr = cnt_msr_base + msr_step * i;
+		bool expect_gp = !(i < nr_counters);
+		uint8_t vector;
+		uint64_t val;
+
+		/* Test event selection register. */
+		vector = wrmsr_safe(esel_msr, test_val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(WRMSR, esel_msr, expect_gp, vector);
+
+		vector = rdmsr_safe(esel_msr, &val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(RDMSR, esel_msr, expect_gp, vector);
+
+		if (!expect_gp)
+			GUEST_ASSERT_PMC_VALUE(RDMSR, esel_msr, val, test_val);
+
+		/* Test counter register. */
+		vector = wrmsr_safe(cnt_msr, test_val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(WRMSR, cnt_msr, expect_gp, vector);
+
+		vector = rdmsr_safe(cnt_msr, &val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(RDMSR, cnt_msr, expect_gp, vector);
+
+		if (!expect_gp)
+			GUEST_ASSERT_PMC_VALUE(RDMSR, cnt_msr, val, test_val);
+	}
 }
 
 static void guest_test_core_counters(void)
 {
+	guest_test_rdwr_core_counters();
 	GUEST_DONE();
 }
 
-- 
2.46.0.662.g92d0881bb0-goog