linux-kernel - [PATCH v4 5/9] KVM: selftests: Test Intel PMU architectural events on fixed counters

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Date:   Mon, 11 Sep 2023 19:43:43 +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 v4 5/9] 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>
---
 .../selftests/kvm/x86_64/pmu_counters_test.c  | 22 +++++++++++++++++++
 1 file changed, 22 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 f47853f3ab84..fe9f38a3557e 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -106,6 +106,28 @@ static void guest_measure_loop(uint8_t idx)
 		GUEST_ASSERT_EQ(expect, !!_rdpmc(i));
 	}
 
+	if (this_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS) < 1)
+		goto done;
+
+	if (idx == INTEL_ARCH_INSTRUCTIONS_RETIRED)
+		i = 0;
+	else if (idx == INTEL_ARCH_CPU_CYCLES)
+		i = 1;
+	else if (idx == PSEUDO_ARCH_REFERENCE_CYCLES)
+		i = 2;
+	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(PMC_IDX_FIXED + i));
+	__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+	wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+
+	GUEST_ASSERT_EQ(expect, !!_rdpmc(PMC_FIXED_RDPMC_BASE | i));
+
+done:
 	GUEST_DONE();
 }
 
-- 
2.39.3