linux-kernel - [PATCH v3 04/11] KVM: selftests: Test Intel PMU architectural events on fixed counters

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Date:   Mon, 14 Aug 2023 19:51:01 +0800
From:   Jinrong Liang <ljr.kernel@...il.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Like Xu <likexu@...cent.com>,
        David Matlack <dmatlack@...gle.com>,
        Aaron Lewis <aaronlewis@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jinrong Liang <cloudliang@...cent.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 04/11] KVM: selftests: Test Intel PMU architectural events on fixed counters

From: Jinrong Liang <cloudliang@...cent.com>

Update test to cover Intel PMU architectural events on fixed counters.
Per Intel SDM, PMU users can also count architecture performance events
on fixed counters (specifically, FIXED_CTR0 for the retired instructions
and FIXED_CTR1 for cpu core cycles event). Therefore, if guest's CPUID
indicates that an architecture event is not available, the corresponding
fixed counter will also not count that event.

Co-developed-by: Like Xu <likexu@...cent.com>
Signed-off-by: Like Xu <likexu@...cent.com>
Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
---
 .../kvm/x86_64/pmu_basic_functionality_test.c | 21 +++++++++++++++++++
 1 file changed, 21 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 c04eb0bdf69f..daa45aa285bb 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
@@ -47,6 +47,7 @@ static uint64_t run_vcpu(struct kvm_vcpu *vcpu, uint64_t *ucall_arg)
 
 static void guest_measure_loop(uint64_t event_code)
 {
+	uint32_t nr_fixed_counter = this_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
 	uint32_t nr_gp_counters = this_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS);
 	uint32_t pmu_version = this_cpu_property(X86_PROPERTY_PMU_VERSION);
 	uint32_t counter_msr;
@@ -73,6 +74,26 @@ static void guest_measure_loop(uint64_t event_code)
 		}
 	}
 
+	if (pmu_version < 2 || nr_fixed_counter < 1)
+		goto done;
+
+	if (event_code == intel_arch_events[INTEL_ARCH_INSTRUCTIONS_RETIRED])
+		i = 0;
+	else if (event_code == intel_arch_events[INTEL_ARCH_CPU_CYCLES])
+		i = 1;
+	else
+		goto done;
+
+	wrmsr(MSR_CORE_PERF_FIXED_CTR0 + i, 0);
+	wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, BIT_ULL(4 * i));
+	wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, BIT_ULL(INTEL_PMC_IDX_FIXED + i));
+
+	__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+
+	wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+	GUEST_SYNC(_rdpmc(RDPMC_FIXED_BASE | i));
+
+done:
 	GUEST_DONE();
 }
 
-- 
2.39.3