[PATCH v5 21/22] KVM: riscv: selftests: Add a test for PMU snapshot functionality

Atish Patra
2024-04-03T08:05:59Z

Verify PMU snapshot functionality by setting up the shared memory
correctly and reading the counter values from the shared memory
instead of the CSR.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
.../testing/selftests/kvm/include/riscv/sbi.h | 25 ++++
.../selftests/kvm/lib/riscv/processor.c | 12 ++
.../selftests/kvm/riscv/sbi_pmu_test.c | 127 ++++++++++++++++++
3 files changed, 164 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/riscv/sbi.h b/tools/testing/selftests/kvm/include/riscv/sbi.h
index 6675ca673c77..8c98bd99d450 100644
--- a/tools/testing/selftests/kvm/include/riscv/sbi.h
+++ b/tools/testing/selftests/kvm/include/riscv/sbi.h
@@ -8,6 +8,12 @@
#ifndef SELFTEST_KVM_SBI_H
#define SELFTEST_KVM_SBI_H

+/* SBI spec version fields */
+#define SBI_SPEC_VERSION_DEFAULT 0x1
+#define SBI_SPEC_VERSION_MAJOR_SHIFT 24
+#define SBI_SPEC_VERSION_MAJOR_MASK 0x7f
+#define SBI_SPEC_VERSION_MINOR_MASK 0xffffff
+
/* SBI return error codes */
#define SBI_SUCCESS 0
#define SBI_ERR_FAILURE -1
@@ -33,6 +39,9 @@ enum sbi_ext_id {
};

enum sbi_ext_base_fid {
+ SBI_EXT_BASE_GET_SPEC_VERSION = 0,
+ SBI_EXT_BASE_GET_IMP_ID,
+ SBI_EXT_BASE_GET_IMP_VERSION,
SBI_EXT_BASE_PROBE_EXT = 3,
};
enum sbi_ext_pmu_fid {
@@ -60,6 +69,12 @@ union sbi_pmu_ctr_info {
};
};

+struct riscv_pmu_snapshot_data {
+ u64 ctr_overflow_mask;
+ u64 ctr_values[64];
+ u64 reserved[447];
+};
+
struct sbiret {
long error;
long value;
@@ -113,4 +128,14 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,

bool guest_sbi_probe_extension(int extid, long *out_val);

+/* Make SBI version */
+static inline unsigned long sbi_mk_version(unsigned long major,
+ unsigned long minor)
+{
+ return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
+ SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
+}
+
+unsigned long get_host_sbi_spec_version(void);
+
#endif /* SELFTEST_KVM_SBI_H */
diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
index e8211f5d6863..ccb35573749c 100644
--- a/tools/testing/selftests/kvm/lib/riscv/processor.c
+++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
@@ -502,3 +502,15 @@ bool guest_sbi_probe_extension(int extid, long *out_val)

return true;
}
+
+unsigned long get_host_sbi_spec_version(void)
+{
+ struct sbiret ret;
+
+ ret = sbi_ecall(SBI_EXT_BASE, SBI_EXT_BASE_GET_SPEC_VERSION, 0,
+ 0, 0, 0, 0, 0);
+
+ GUEST_ASSERT(!ret.error);
+
+ return ret.value;
+}
diff --git a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
index 8e7c7a3172d8..7d195be5c3d9 100644
--- a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
+++ b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
@@ -19,6 +19,11 @@
#define RISCV_MAX_PMU_COUNTERS 64
union sbi_pmu_ctr_info ctrinfo_arr[RISCV_MAX_PMU_COUNTERS];

+/* Snapshot shared memory data */
+#define PMU_SNAPSHOT_GPA_BASE BIT(30)
+static void *snapshot_gva;
+static vm_paddr_t snapshot_gpa;
+
/* Cache the available counters in a bitmask */
static unsigned long counter_mask_available;

@@ -178,6 +183,32 @@ static unsigned long read_counter(int idx, union sbi_pmu_ctr_info ctrinfo)
return counter_val;
}

+static inline void verify_sbi_requirement_assert(void)
+{
+ long out_val = 0;
+ bool probe;
+
+ probe = guest_sbi_probe_extension(SBI_EXT_PMU, &out_val);
+ GUEST_ASSERT(probe && out_val == 1);
+
+ if (get_host_sbi_spec_version() < sbi_mk_version(2, 0))
+ __GUEST_ASSERT(0, "SBI implementation version doesn't support PMU Snapshot");
+}
+
+static void snapshot_set_shmem(vm_paddr_t gpa, unsigned long flags)
+{
+ unsigned long lo = (unsigned long)gpa;
+#if __riscv_xlen == 32
+ unsigned long hi = (unsigned long)(gpa >> 32);
+#else
+ unsigned long hi = gpa == -1 ? -1 : 0;
+#endif
+ struct sbiret ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_SNAPSHOT_SET_SHMEM,
+ lo, hi, flags, 0, 0, 0);
+
+ GUEST_ASSERT(ret.value == 0 && ret.error == 0);
+}
+
static void test_pmu_event(unsigned long event)
{
unsigned long counter;
@@ -210,6 +241,41 @@ static void test_pmu_event(unsigned long event)
stop_reset_counter(counter, 0);
}

+static void test_pmu_event_snapshot(unsigned long event)
+{
+ unsigned long counter;
+ unsigned long counter_value_pre, counter_value_post;
+ unsigned long counter_init_value = 100;
+ struct riscv_pmu_snapshot_data *snapshot_data = snapshot_gva;
+
+ counter = get_counter_index(0, counter_mask_available, 0, event);
+ counter_value_pre = read_counter(counter, ctrinfo_arr[counter]);
+
+ /* Do not set the initial value */
+ start_counter(counter, 0, 0);
+ dummy_func_loop(10000);
+ stop_counter(counter, SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT);
+
+ /* The counter value is updated w.r.t relative index of cbase */
+ counter_value_post = READ_ONCE(snapshot_data->ctr_values[0]);
+ __GUEST_ASSERT(counter_value_post > counter_value_pre,
+ "counter_value_post %lx counter_value_pre %lx\n",
+ counter_value_post, counter_value_pre);
+
+ /* Now set the initial value and compare */
+ WRITE_ONCE(snapshot_data->ctr_values[0], counter_init_value);
+ start_counter(counter, SBI_PMU_START_FLAG_INIT_SNAPSHOT, 0);
+ dummy_func_loop(10000);
+ stop_counter(counter, SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT);
+
+ counter_value_post = READ_ONCE(snapshot_data->ctr_values[0]);
+ __GUEST_ASSERT(counter_value_post > counter_init_value,
+ "counter_value_post %lx counter_init_value %lx for counter\n",
+ counter_value_post, counter_init_value);
+
+ stop_reset_counter(counter, 0);
+}
+
static void test_invalid_event(void)
{
struct sbiret ret;
@@ -272,6 +338,34 @@ static void test_pmu_basic_sanity(void)
GUEST_DONE();
}

+static void test_pmu_events_snaphost(void)
+{
+ int num_counters = 0;
+ struct riscv_pmu_snapshot_data *snapshot_data = snapshot_gva;
+ int i;
+
+ /* Verify presence of SBI PMU and minimum requrired SBI version */
+ verify_sbi_requirement_assert();
+
+ snapshot_set_shmem(snapshot_gpa, 0);
+
+ /* Get the counter details */
+ num_counters = get_num_counters();
+ update_counter_info(num_counters);
+
+ /* Validate shared memory access */
+ GUEST_ASSERT_EQ(READ_ONCE(snapshot_data->ctr_overflow_mask), 0);
+ for (i = 0; i < num_counters; i++) {
+ if (counter_mask_available & (BIT(i)))
+ GUEST_ASSERT_EQ(READ_ONCE(snapshot_data->ctr_values[i]), 0);
+ }
+ /* Only these two events are guranteed to be present */
+ test_pmu_event_snapshot(SBI_PMU_HW_CPU_CYCLES);
+ test_pmu_event_snapshot(SBI_PMU_HW_INSTRUCTIONS);
+
+ GUEST_DONE();
+}
+
static void run_vcpu(struct kvm_vcpu *vcpu)
{
struct ucall uc;
@@ -328,13 +422,46 @@ static void test_vm_events_test(void *guest_code)
test_vm_destroy(vm);
}

+static void test_vm_setup_snapshot_mem(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+{
+ /* PMU Snapshot requires single page only */
+ vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, PMU_SNAPSHOT_GPA_BASE, 1, 1, 0);
+ /* PMU_SNAPSHOT_GPA_BASE is identity mapped */
+ virt_map(vm, PMU_SNAPSHOT_GPA_BASE, PMU_SNAPSHOT_GPA_BASE, 1);
+
+ snapshot_gva = (void *)(PMU_SNAPSHOT_GPA_BASE);
+ snapshot_gpa = addr_gva2gpa(vcpu->vm, (vm_vaddr_t)snapshot_gva);
+ sync_global_to_guest(vcpu->vm, snapshot_gva);
+ sync_global_to_guest(vcpu->vm, snapshot_gpa);
+}
+
+static void test_vm_events_snapshot_test(void *guest_code)
+{
+ struct kvm_vm *vm = NULL;
+ struct kvm_vcpu *vcpu;
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+ __TEST_REQUIRE(__vcpu_has_sbi_ext(vcpu, KVM_RISCV_SBI_EXT_PMU),
+ "SBI PMU not available, skipping test");
+
+ test_vm_setup_snapshot_mem(vm, vcpu);
+
+ run_vcpu(vcpu);
+
+ test_vm_destroy(vm);
+}
+
int main(void)
{
+ pr_info("SBI PMU basic test : starting\n");
test_vm_basic_test(test_pmu_basic_sanity);
pr_info("SBI PMU basic test : PASS\n");

test_vm_events_test(test_pmu_events);
pr_info("SBI PMU event verification test : PASS\n");

+ test_vm_events_snapshot_test(test_pmu_events_snaphost);
+ pr_info("SBI PMU event verification with snapshot test : PASS\n");
+
return 0;
}
--
2.34.1