Re: [PATCH v8 22/24] KVM: riscv: selftests: Add a test for PMU snapshot functionality

On 4/20/24 8:17 PM, Atish Patra wrote:

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: Andrew Jones ajones@ventanamicro.com Reviewed-by: Anup Patel anup@brainfault.org Signed-off-by: Atish Patra atishp@rivosinc.com

LGTM

Reviewed-by: Muhammad Usama Anjum usama.anjum@collabora.com

---

.../testing/selftests/kvm/include/riscv/sbi.h | 25 +++ .../selftests/kvm/lib/riscv/processor.c | 12 ++ .../selftests/kvm/riscv/sbi_pmu_test.c | 144 ++++++++++++++++++ 3 files changed, 181 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/riscv/sbi.h b/tools/testing/selftests/kvm/include/riscv/sbi.h index 6675ca673c77..046b432ae896 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 & SBI_SPEC_VERSION_MINOR_MASK);
  

+}

+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 7c81691e39c5..9002ff451abf 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; @@ -186,6 +191,32 @@ 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; @@ -234,6 +265,59 @@ 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,

•        "Event update verification failed: post [%lx] pre [%lx]\n",
  

•        counter_value_post, counter_value_pre);
  

• /*

• * We can't just update the counter without starting it.
  

• * Do start/stop twice to simulate that by first initializing to a very
  

• * high value and a low value after that.
  

• */
  

• WRITE_ONCE(snapshot_data->ctr_values[0], ULONG_MAX/2);
• start_counter(counter, SBI_PMU_START_FLAG_INIT_SNAPSHOT, 0);
• stop_counter(counter, SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT);
• counter_value_pre = READ_ONCE(snapshot_data->ctr_values[0]);
• WRITE_ONCE(snapshot_data->ctr_values[0], counter_init_value);
• start_counter(counter, SBI_PMU_START_FLAG_INIT_SNAPSHOT, 0);
• stop_counter(counter, SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT);
• counter_value_post = READ_ONCE(snapshot_data->ctr_values[0]);
• __GUEST_ASSERT(counter_value_pre > counter_value_post,

•        "Counter reinitialization verification failed : post [%lx] 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,

•        "Event update verification failed: post [%lx] pre [%lx]\n",
  

•        counter_value_post, counter_init_value);
  

• stop_reset_counter(counter, 0);

+}

static void test_invalid_event(void) { struct sbiret ret; @@ -301,6 +385,34 @@ 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; @@ -357,6 +469,35 @@ 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) { test_vm_basic_test(test_pmu_basic_sanity); @@ -365,5 +506,8 @@ int main(void) 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;

}