[PATCH v4 7/9] KVM: selftests: Test consistency of CPUID with num of fixed counters

[Jinrong Liang <ljr.kernel@xxxxxxxxx>]

From: Jinrong Liang <cloudliang@xxxxxxxxxxx>

Add test to check if non-existent counters can be accessed in guest after
determining the number of Intel generic performance counters by CPUID.
Per SDM, fixed-function performance counter 'i' is supported if ECX[i] ||
(EDX[4:0] > i). KVM doesn't emulate more counters than it can support.

Co-developed-by: Like Xu <likexu@xxxxxxxxxxx>
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
Signed-off-by: Jinrong Liang <cloudliang@xxxxxxxxxxx>
---
 .../selftests/kvm/x86_64/pmu_counters_test.c  | 28 +++++++++++++++++++
 1 file changed, 28 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 e636323e202c..df76f0f2bfd0 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -251,8 +251,32 @@ static void test_oob_gp_counter(uint8_t eax_gp_num, uint64_t perf_cap)
 	kvm_vm_free(vm);
 }
 
+static void guest_rd_wr_fixed_counter(void)
+{
+	uint8_t nr_fixed_counters = this_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
+
+	__guest_wrmsr_rdmsr(MSR_CORE_PERF_FIXED_CTR0, nr_fixed_counters, true);
+}
+
+static void test_oob_fixed_ctr(uint8_t edx_fixed_num)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	vm = pmu_vm_create_with_one_vcpu(&vcpu, guest_rd_wr_fixed_counter);
+
+	vcpu_set_cpuid_property(vcpu, X86_PROPERTY_PMU_FIXED_COUNTERS_BITMASK, 0);
+	vcpu_set_cpuid_property(vcpu, X86_PROPERTY_PMU_NR_FIXED_COUNTERS,
+				edx_fixed_num);
+
+	run_vcpu(vcpu);
+
+	kvm_vm_free(vm);
+}
+
 static void test_intel_counters_num(void)
 {
+	uint8_t nr_fixed_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
 	uint8_t nr_gp_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS);
 	unsigned int i;
 
@@ -271,6 +295,10 @@ static void test_intel_counters_num(void)
 		/* KVM doesn't emulate more counters than it can support. */
 		test_oob_gp_counter(nr_gp_counters + 1, perf_caps[i]);
 	}
+
+	test_oob_fixed_ctr(0);
+	test_oob_fixed_ctr(nr_fixed_counters);
+	test_oob_fixed_ctr(nr_fixed_counters + 1);
 }
 
 int main(int argc, char *argv[])
-- 
2.39.3