[PATCH v8 22/24] KVM: riscv: selftests: Add a test for PMU snapshot functionality
Muhammad Usama Anjum
usama.anjum at collabora.com
Tue Apr 23 02:00:20 PDT 2024
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 at ventanamicro.com>
> Reviewed-by: Anup Patel <anup at brainfault.org>
> Signed-off-by: Atish Patra <atishp at rivosinc.com>
LGTM
Reviewed-by: Muhammad Usama Anjum <usama.anjum at 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;
> }
--
BR,
Muhammad Usama Anjum
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