[PATCH v2 7/8] KVM: selftests: Test Intel supported fixed counters bit mask

[Jinrong Liang <ljr.kernel@gmail.com>]

From: Like Xu <likexu@tencent.com>

Add a test to check that fixed counters enabled via guest
CPUID.0xA.ECX (instead of EDX[04:00]) work as normal as usual.

Co-developed-by: Jinrong Liang <cloudliang@tencent.com>
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Signed-off-by: Like Xu <likexu@tencent.com>
---
 .../kvm/x86_64/pmu_basic_functionality_test.c | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86_64/pmu_basic_functionality_test.c b/tools/testing/selftests/kvm/x86_64/pmu_basic_functionality_test.c
index e19f8c2774c5..108cfe254095 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_basic_functionality_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_basic_functionality_test.c
@@ -298,10 +298,81 @@ static void intel_test_counters_num(void)
 	}
 }
 
+static void intel_guest_run_fixed_counters(uint64_t supported_bitmask,
+					   uint8_t max_fixed_num)
+{
+	unsigned int i;
+	uint64_t msr_val;
+
+	for (i = 0; i < max_fixed_num; i++) {
+		if (!(supported_bitmask & BIT_ULL(i)))
+			continue;
+
+		if (wrmsr_safe(MSR_CORE_PERF_FIXED_CTR0 + i, 0) == GP_VECTOR)
+			GUEST_SYNC(GP_VECTOR);
+
+		wrmsr_safe(MSR_CORE_PERF_FIXED_CTR_CTRL, BIT_ULL(4 * i));
+		wrmsr_safe(MSR_CORE_PERF_GLOBAL_CTRL, BIT_ULL(INTEL_PMC_IDX_FIXED + i));
+		__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+		wrmsr_safe(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+		rdmsr_safe(MSR_CORE_PERF_FIXED_CTR0 + i, &msr_val);
+
+		GUEST_SYNC(msr_val);
+	}
+
+	GUEST_DONE();
+}
+
+static void test_fixed_counters_setup(struct kvm_vcpu *vcpu, uint8_t edx_fix_num,
+				      uint32_t fixed_bitmask, bool expected)
+{
+	struct kvm_cpuid_entry2 *entry;
+	uint8_t max_fixed_num = X86_INTEL_MAX_FIXED_CTR_NUM;
+	uint64_t supported_bitmask = 0;
+	uint64_t msr_val;
+	unsigned int i;
+
+	entry = vcpu_get_cpuid_entry(vcpu, 0xa);
+	entry->ecx = fixed_bitmask;
+	entry->edx = (entry->edx & ~FIXED_CTR_NUM_MASK) | edx_fix_num;
+	vcpu_set_cpuid(vcpu);
+
+	for (i = 0; i < max_fixed_num; i++) {
+		if (entry->ecx & BIT_ULL(i) ||
+		    ((entry->edx & FIXED_CTR_NUM_MASK) > i))
+			supported_bitmask |= BIT_ULL(i);
+	}
+
+	vcpu_args_set(vcpu, 2, supported_bitmask, max_fixed_num);
+
+	while (run_vcpu(vcpu, &msr_val) != UCALL_DONE)
+		TEST_ASSERT(!!msr_val == expected,
+			    "Unexpected when testing fixed counter.");
+}
+
+static void intel_test_fixed_counters(void)
+{
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	uint32_t ecx;
+	uint8_t edx, num = X86_INTEL_MAX_FIXED_CTR_NUM;
+
+	for (edx = 0; edx <= num; edx++) {
+		/* KVM doesn't emulate more fixed counters than it can support. */
+		for (ecx = 0; ecx <= (BIT_ULL(num) - 1); ecx++) {
+			vm = pmu_vm_create_with_one_vcpu(&vcpu,
+							 intel_guest_run_fixed_counters);
+			test_fixed_counters_setup(vcpu, edx, ecx, true);
+			kvm_vm_free(vm);
+		}
+	}
+}
+
 static void intel_test_pmu_cpuid(void)
 {
 	intel_test_arch_events();
 	intel_test_counters_num();
+	intel_test_fixed_counters();
 }
 
 int main(int argc, char *argv[])
-- 
2.31.1