linux-kernel - [PATCH 11/13] selftests: KVM: aarch64: Add PMU test to chain all the counters

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Message-ID: <20230213180234.2885032-12-rananta@google.com>
Date:   Mon, 13 Feb 2023 18:02:32 +0000
From:   Raghavendra Rao Ananta <rananta@...gle.com>
To:     Oliver Upton <oupton@...gle.com>,
        Reiji Watanabe <reijiw@...gle.com>,
        Marc Zyngier <maz@...nel.org>,
        Ricardo Koller <ricarkol@...gle.com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        Colton Lewis <coltonlewis@...gle.com>,
        Raghavendra Rao Anata <rananta@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH 11/13] selftests: KVM: aarch64: Add PMU test to chain all the counters

Extend the vCPU migration test to occupy all the vPMU counters,
by configuring chained events on alternate counter-ids and chaining
them with its corresponding predecessor counter, and verify against
the extended behavior.

Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
---
 .../testing/selftests/kvm/aarch64/vpmu_test.c | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_test.c b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
index de725f4339ad5..fd00acb9391c8 100644
--- a/tools/testing/selftests/kvm/aarch64/vpmu_test.c
+++ b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
@@ -710,6 +710,63 @@ static void test_chained_count(int pmc_idx)
 	pmu_irq_exit(chained_pmc_idx);
 }
 
+static void test_chain_all_counters(void)
+{
+	int i;
+	uint64_t cnt, pmcr_n = get_pmcr_n();
+	struct pmc_accessor *acc = &pmc_accessors[0];
+
+	/*
+	 * Test the occupancy of all the event counters, by chaining the
+	 * alternate counters. The test assumes that the host hasn't
+	 * occupied any counters. Hence, if the test fails, it could be
+	 * because all the counters weren't available to the guest or
+	 * there's actually a bug in KVM.
+	 */
+
+	/*
+	 * Configure even numbered counters to count cpu-cycles, and chain
+	 * each of them with its odd numbered counter.
+	 */
+	for (i = 0; i < pmcr_n; i++) {
+		if (i % 2) {
+			acc->write_typer(i, ARMV8_PMUV3_PERFCTR_CHAIN);
+			acc->write_cntr(i, 1);
+		} else {
+			pmu_irq_init(i);
+			acc->write_cntr(i, PRE_OVERFLOW_32);
+			acc->write_typer(i, ARMV8_PMUV3_PERFCTR_CPU_CYCLES);
+		}
+		enable_counter(i);
+	}
+
+	/* Introduce some cycles */
+	execute_precise_instrs(500, ARMV8_PMU_PMCR_E);
+
+	/*
+	 * An overflow interrupt should've arrived for all the even numbered
+	 * counters but none for the odd numbered ones. The odd numbered ones
+	 * should've incremented exactly by 1.
+	 */
+	for (i = 0; i < pmcr_n; i++) {
+		if (i % 2) {
+			GUEST_ASSERT_1(!pmu_irq_received(i), i);
+
+			cnt = acc->read_cntr(i);
+			GUEST_ASSERT_2(cnt == 2, i, cnt);
+		} else {
+			GUEST_ASSERT_1(pmu_irq_received(i), i);
+		}
+	}
+
+	/* Cleanup the states */
+	for (i = 0; i < pmcr_n; i++) {
+		if (i % 2 == 0)
+			pmu_irq_exit(i);
+		disable_counter(i);
+	}
+}
+
 static void test_event_count(uint64_t event, int pmc_idx, bool expect_count)
 {
 	switch (event) {
@@ -739,6 +796,9 @@ static void test_basic_pmu_functionality(void)
 
 	/* Test chained events */
 	test_chained_count(0);
+
+	/* Test running chained events on all the implemented counters */
+	test_chain_all_counters();
 }
 
 /*
-- 
2.39.1.581.gbfd45094c4-goog