[REPOST PATCH 12/16] selftests: KVM: aarch64: Test PMU overflow/IRQ functionality

Raghavendra Rao Ananta
2023-02-15T01:08:28Z

Extend the vCPU migration test to also validate the vPMU's
functionality when set up for overflow conditions.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
.../testing/selftests/kvm/aarch64/vpmu_test.c | 223 ++++++++++++++++--
1 file changed, 198 insertions(+), 25 deletions(-)

diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_test.c b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
index 0c9d801f4e602..066dc17fa3906 100644
--- a/tools/testing/selftests/kvm/aarch64/vpmu_test.c
+++ b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
@@ -21,7 +21,9 @@
*
* 4. Since the PMU registers are per-cpu, stress KVM by frequently
* migrating the guest vCPU to random pCPUs in the system, and check
- * if the vPMU is still behaving as expected.
+ * if the vPMU is still behaving as expected. The sub-tests include
+ * testing basic functionalities such as basic counters behavior,
+ * overflow, and overflow interrupts.
*
* Copyright (c) 2022 Google LLC.
*
@@ -41,13 +43,27 @@
#include <sys/sysinfo.h>

#include "delay.h"
+#include "gic.h"
+#include "spinlock.h"

/* The max number of the PMU event counters (excluding the cycle counter) */
#define ARMV8_PMU_MAX_GENERAL_COUNTERS (ARMV8_PMU_MAX_COUNTERS - 1)

+/* The cycle counter bit position that's common among the PMU registers */
+#define ARMV8_PMU_CYCLE_COUNTER_IDX 31
+
/* The max number of event numbers that's supported */
#define ARMV8_PMU_MAX_EVENTS 64

+#define PMU_IRQ 23
+
+#define COUNT_TO_OVERFLOW 0xFULL
+#define PRE_OVERFLOW_32 (GENMASK(31, 0) - COUNT_TO_OVERFLOW + 1)
+#define PRE_OVERFLOW_64 (GENMASK(63, 0) - COUNT_TO_OVERFLOW + 1)
+
+#define GICD_BASE_GPA 0x8000000ULL
+#define GICR_BASE_GPA 0x80A0000ULL
+
#define msecs_to_usecs(msec) ((msec) * 1000LL)

/*
@@ -162,6 +178,17 @@ static inline void write_sel_evtyper(int sel, unsigned long val)
isb();
}

+static inline void write_pmovsclr(unsigned long val)
+{
+ write_sysreg(val, pmovsclr_el0);
+ isb();
+}
+
+static unsigned long read_pmovsclr(void)
+{
+ return read_sysreg(pmovsclr_el0);
+}
+
static inline void enable_counter(int idx)
{
uint64_t v = read_sysreg(pmcntenset_el0);
@@ -178,11 +205,33 @@ static inline void disable_counter(int idx)
isb();
}

+static inline void enable_irq(int idx)
+{
+ uint64_t v = read_sysreg(pmcntenset_el0);
+
+ write_sysreg(BIT(idx) | v, pmintenset_el1);
+ isb();
+}
+
+static inline void disable_irq(int idx)
+{
+ uint64_t v = read_sysreg(pmcntenset_el0);
+
+ write_sysreg(BIT(idx) | v, pmintenclr_el1);
+ isb();
+}
+
static inline uint64_t read_cycle_counter(void)
{
return read_sysreg(pmccntr_el0);
}

+static inline void write_cycle_counter(uint64_t v)
+{
+ write_sysreg(v, pmccntr_el0);
+ isb();
+}
+
static inline void reset_cycle_counter(void)
{
uint64_t v = read_sysreg(pmcr_el0);
@@ -289,6 +338,15 @@ struct guest_data {

static struct guest_data guest_data;

+/* Data to communicate among guest threads */
+struct guest_irq_data {
+ uint32_t pmc_idx_bmap;
+ uint32_t irq_received_bmap;
+ struct spinlock lock;
+};
+
+static struct guest_irq_data guest_irq_data;
+
#define VCPU_MIGRATIONS_TEST_ITERS_DEF 1000
#define VCPU_MIGRATIONS_TEST_MIGRATION_FREQ_MS 2

@@ -322,6 +380,79 @@ static void guest_sync_handler(struct ex_regs *regs)
expected_ec = INVALID_EC;
}

+static void guest_validate_irq(int pmc_idx, uint32_t pmovsclr, uint32_t pmc_idx_bmap)
+{
+ /*
+ * Fail if there's an interrupt from unexpected PMCs.
+ * All the expected events' IRQs may not arrive at the same time.
+ * Hence, check if the interrupt is valid only if it's expected.
+ */
+ if (pmovsclr & BIT(pmc_idx)) {
+ GUEST_ASSERT_3(pmc_idx_bmap & BIT(pmc_idx), pmc_idx, pmovsclr, pmc_idx_bmap);
+ write_pmovsclr(BIT(pmc_idx));
+ }
+}
+
+static void guest_irq_handler(struct ex_regs *regs)
+{
+ uint32_t pmc_idx_bmap;
+ uint64_t i, pmcr_n = get_pmcr_n();
+ uint32_t pmovsclr = read_pmovsclr();
+ unsigned int intid = gic_get_and_ack_irq();
+
+ /* No other IRQ apart from the PMU IRQ is expected */
+ GUEST_ASSERT_1(intid == PMU_IRQ, intid);
+
+ spin_lock(&guest_irq_data.lock);
+ pmc_idx_bmap = READ_ONCE(guest_irq_data.pmc_idx_bmap);
+
+ for (i = 0; i < pmcr_n; i++)
+ guest_validate_irq(i, pmovsclr, pmc_idx_bmap);
+ guest_validate_irq(ARMV8_PMU_CYCLE_COUNTER_IDX, pmovsclr, pmc_idx_bmap);
+
+ /* Mark IRQ as recived for the corresponding PMCs */
+ WRITE_ONCE(guest_irq_data.irq_received_bmap, pmovsclr);
+ spin_unlock(&guest_irq_data.lock);
+
+ gic_set_eoi(intid);
+}
+
+static int pmu_irq_received(int pmc_idx)
+{
+ bool irq_received;
+
+ spin_lock(&guest_irq_data.lock);
+ irq_received = READ_ONCE(guest_irq_data.irq_received_bmap) & BIT(pmc_idx);
+ WRITE_ONCE(guest_irq_data.irq_received_bmap, guest_irq_data.pmc_idx_bmap & ~BIT(pmc_idx));
+ spin_unlock(&guest_irq_data.lock);
+
+ return irq_received;
+}
+
+static void pmu_irq_init(int pmc_idx)
+{
+ write_pmovsclr(BIT(pmc_idx));
+
+ spin_lock(&guest_irq_data.lock);
+ WRITE_ONCE(guest_irq_data.irq_received_bmap, guest_irq_data.pmc_idx_bmap & ~BIT(pmc_idx));
+ WRITE_ONCE(guest_irq_data.pmc_idx_bmap, guest_irq_data.pmc_idx_bmap | BIT(pmc_idx));
+ spin_unlock(&guest_irq_data.lock);
+
+ enable_irq(pmc_idx);
+}
+
+static void pmu_irq_exit(int pmc_idx)
+{
+ write_pmovsclr(BIT(pmc_idx));
+
+ spin_lock(&guest_irq_data.lock);
+ WRITE_ONCE(guest_irq_data.irq_received_bmap, guest_irq_data.pmc_idx_bmap & ~BIT(pmc_idx));
+ WRITE_ONCE(guest_irq_data.pmc_idx_bmap, guest_irq_data.pmc_idx_bmap & ~BIT(pmc_idx));
+ spin_unlock(&guest_irq_data.lock);
+
+ disable_irq(pmc_idx);
+}
+
/*
* Run the given operation that should trigger an exception with the
* given exception class. The exception handler (guest_sync_handler)
@@ -420,12 +551,20 @@ static void execute_precise_instrs(int num, uint32_t pmcr)
precise_instrs_loop(loop, pmcr);
}

-static void test_instructions_count(int pmc_idx, bool expect_count)
+static void test_instructions_count(int pmc_idx, bool expect_count, bool test_overflow)
{
int i;
struct pmc_accessor *acc;
- uint64_t cnt;
- int instrs_count = 100;
+ uint64_t cntr_val = 0;
+ int instrs_count = 500;
+
+ if (test_overflow) {
+ /* Overflow scenarios can only be tested when a count is expected */
+ GUEST_ASSERT_1(expect_count, pmc_idx);
+
+ cntr_val = PRE_OVERFLOW_32;
+ pmu_irq_init(pmc_idx);
+ }

enable_counter(pmc_idx);

@@ -433,41 +572,68 @@ static void test_instructions_count(int pmc_idx, bool expect_count)
for (i = 0; i < ARRAY_SIZE(pmc_accessors); i++) {
acc = &pmc_accessors[i];

- pmu_disable_reset();
-
+ acc->write_cntr(pmc_idx, cntr_val);
acc->write_typer(pmc_idx, ARMV8_PMUV3_PERFCTR_INST_RETIRED);

- /* Enable the PMU and execute precisely number of instructions as a workload */
- execute_precise_instrs(instrs_count, read_sysreg(pmcr_el0) | ARMV8_PMU_PMCR_E);
+ /*
+ * Enable the PMU and execute a precise number of instructions as a workload.
+ * Since execute_precise_instrs() disables the PMU at the end, 'instrs_count'
+ * should have enough instructions to raise an IRQ.
+ */
+ execute_precise_instrs(instrs_count, ARMV8_PMU_PMCR_E);

- /* If a count is expected, the counter should be increased by 'instrs_count' */
- cnt = acc->read_cntr(pmc_idx);
- GUEST_ASSERT_4(expect_count == (cnt == instrs_count),
- i, expect_count, cnt, instrs_count);
+ /*
+ * If an overflow is expected, only check for the overflag flag.
+ * As overflow interrupt is enabled, the interrupt would add additional
+ * instructions and mess up the precise instruction count. Hence, measure
+ * the instructions count only when the test is not set up for an overflow.
+ */
+ if (test_overflow) {
+ GUEST_ASSERT_2(pmu_irq_received(pmc_idx), pmc_idx, i);
+ } else {
+ uint64_t cnt = acc->read_cntr(pmc_idx);
+
+ GUEST_ASSERT_4(expect_count == (cnt == instrs_count),
+ pmc_idx, i, cnt, expect_count);
+ }
}

- disable_counter(pmc_idx);
+ if (test_overflow)
+ pmu_irq_exit(pmc_idx);
}

-static void test_cycles_count(bool expect_count)
+static void test_cycles_count(bool expect_count, bool test_overflow)
{
uint64_t cnt;

- pmu_enable();
- reset_cycle_counter();
+ if (test_overflow) {
+ /* Overflow scenarios can only be tested when a count is expected */
+ GUEST_ASSERT(expect_count);
+
+ write_cycle_counter(PRE_OVERFLOW_64);
+ pmu_irq_init(ARMV8_PMU_CYCLE_COUNTER_IDX);
+ } else {
+ reset_cycle_counter();
+ }

/* Count cycles in EL0 and EL1 */
write_pmccfiltr(0);
enable_cycle_counter();

+ /* Enable the PMU and execute precisely number of instructions as a workload */
+ execute_precise_instrs(500, read_sysreg(pmcr_el0) | ARMV8_PMU_PMCR_E);
cnt = read_cycle_counter();

/*
* If a count is expected by the test, the cycle counter should be increased by
- * at least 1, as there is at least one instruction between enabling the
+ * at least 1, as there are a number of instructions between enabling the
* counter and reading the counter.
*/
GUEST_ASSERT_2(expect_count == (cnt > 0), cnt, expect_count);
+ if (test_overflow) {
+ GUEST_ASSERT_2(pmu_irq_received(ARMV8_PMU_CYCLE_COUNTER_IDX), cnt, expect_count);
+ pmu_irq_exit(ARMV8_PMU_CYCLE_COUNTER_IDX);
+ }

disable_cycle_counter();
pmu_disable_reset();
@@ -477,19 +643,28 @@ static void test_event_count(uint64_t event, int pmc_idx, bool expect_count)
{
switch (event) {
case ARMV8_PMUV3_PERFCTR_INST_RETIRED:
- test_instructions_count(pmc_idx, expect_count);
+ test_instructions_count(pmc_idx, expect_count, false);
break;
case ARMV8_PMUV3_PERFCTR_CPU_CYCLES:
- test_cycles_count(expect_count);
+ test_cycles_count(expect_count, false);
break;
}
}

static void test_basic_pmu_functionality(void)
{
+ local_irq_disable();
+ gic_init(GIC_V3, 1, (void *)GICD_BASE_GPA, (void *)GICR_BASE_GPA);
+ gic_irq_enable(PMU_IRQ);
+ local_irq_enable();
+
/* Test events on generic and cycle counters */
- test_instructions_count(0, true);
- test_cycles_count(true);
+ test_instructions_count(0, true, false);
+ test_cycles_count(true, false);
+
+ /* Test overflow with interrupts on generic and cycle counters */
+ test_instructions_count(0, true, true);
+ test_cycles_count(true, true);
}

/*
@@ -813,9 +988,6 @@ static void guest_code(void)
GUEST_DONE();
}

-#define GICD_BASE_GPA 0x8000000ULL
-#define GICR_BASE_GPA 0x80A0000ULL
-
static unsigned long *
set_event_filters(struct kvm_vcpu *vcpu, struct kvm_pmu_event_filter *pmu_event_filters)
{
@@ -866,7 +1038,7 @@ create_vpmu_vm(void *guest_code, struct kvm_pmu_event_filter *pmu_event_filters)
struct kvm_vcpu *vcpu;
struct kvm_vcpu_init init;
uint8_t pmuver, ec;
- uint64_t dfr0, irq = 23;
+ uint64_t dfr0, irq = PMU_IRQ;
struct vpmu_vm *vpmu_vm;
struct kvm_device_attr irq_attr = {
.group = KVM_ARM_VCPU_PMU_V3_CTRL,
@@ -883,6 +1055,7 @@ create_vpmu_vm(void *guest_code, struct kvm_pmu_event_filter *pmu_event_filters)

vpmu_vm->vm = vm = vm_create(1);
vm_init_descriptor_tables(vm);
+ vm_install_exception_handler(vm, VECTOR_IRQ_CURRENT, guest_irq_handler);

/* Catch exceptions for easier debugging */
for (ec = 0; ec < ESR_EC_NUM; ec++) {
--
2.39.1.581.gbfd45094c4-goog