Re: [PATCH v4 14/15] KVM: riscv: selftests: Add a test for PMU snapshot functionality

On Wed, Feb 28, 2024 at 05:01:29PM -0800, 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.

Signed-off-by: Atish Patra atishp@rivosinc.com

.../selftests/kvm/include/riscv/processor.h | 25 ++++ .../selftests/kvm/lib/riscv/processor.c | 12 ++ tools/testing/selftests/kvm/riscv/sbi_pmu.c | 124 ++++++++++++++++++ 3 files changed, 161 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/riscv/processor.h b/tools/testing/selftests/kvm/include/riscv/processor.h index a49a39c8e8d4..e114d039e87b 100644 --- a/tools/testing/selftests/kvm/include/riscv/processor.h +++ b/tools/testing/selftests/kvm/include/riscv/processor.h @@ -173,6 +173,7 @@ enum sbi_ext_id { }; enum sbi_ext_base_fid {

• SBI_EXT_BASE_GET_IMP_VERSION = 2, SBI_EXT_BASE_PROBE_EXT = 3,

}; @@ -201,6 +202,12 @@ 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; @@ -247,6 +254,14 @@ enum sbi_pmu_ctr_type { #define SBI_PMU_STOP_FLAG_RESET (1 << 0) #define SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT BIT(1) +#define SBI_STA_SHMEM_DISABLE -1

unrelated change

+/* 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

struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, unsigned long arg1, unsigned long arg2, unsigned long arg3, unsigned long arg4, @@ -254,6 +269,16 @@ 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;
  

+}

We should probably just synch sbi.h into tools, since we need plenty from it.

+unsigned long get_host_sbi_impl_version(void);

static inline void local_irq_enable(void) { csr_set(CSR_SSTATUS, SR_SIE); diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c index ec66d331a127..b0162d923e38 100644 --- a/tools/testing/selftests/kvm/lib/riscv/processor.c +++ b/tools/testing/selftests/kvm/lib/riscv/processor.c @@ -499,3 +499,15 @@ bool guest_sbi_probe_extension(int extid, long *out_val) return true; }

+unsigned long get_host_sbi_impl_version(void) +{

• struct sbiret ret;
• ret = sbi_ecall(SBI_EXT_BASE, SBI_EXT_BASE_GET_IMP_VERSION, 0,

•        0, 0, 0, 0, 0);
  

• GUEST_ASSERT(!ret.error);
• return ret.value;

+} diff --git a/tools/testing/selftests/kvm/riscv/sbi_pmu.c b/tools/testing/selftests/kvm/riscv/sbi_pmu.c index fc1fc5eea99e..8ea2a6db6610 100644 --- a/tools/testing/selftests/kvm/riscv/sbi_pmu.c +++ b/tools/testing/selftests/kvm/riscv/sbi_pmu.c @@ -21,6 +21,11 @@ #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 (1 << 30) +static void *snapshot_gva; +static vm_paddr_t snapshot_gpa;

/* Cache the available counters in a bitmask */ static unsigned long counter_mask_available; @@ -173,6 +178,20 @@ static void stop_counter(unsigned long counter, unsigned long stop_flags) counter, ret.error); } +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; @@ -207,6 +226,43 @@ static void test_pmu_event(unsigned long event) stop_counter(counter, SBI_PMU_STOP_FLAG_RESET); } +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_FROM_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_counter(counter, SBI_PMU_STOP_FLAG_RESET);

This function is almost identical to test_pmu_event(). If we change one, we'll likely have to change the other. We should have a single function which can be used by both tests. We can do that by passing a function pointer for the read which is different for non-snapshot and snapshot.

+}

static void test_invalid_event(void) { struct sbiret ret; @@ -270,6 +326,41 @@ static void test_pmu_basic_sanity(int cpu) GUEST_DONE(); } +static void test_pmu_events_snaphost(int cpu)

unnecessary cpu parameter

+{

• long out_val = 0;
• bool probe;
• int num_counters = 0;
• unsigned long sbi_impl_version;
• struct riscv_pmu_snapshot_data *snapshot_data = snapshot_gva;
• int i;
• probe = guest_sbi_probe_extension(SBI_EXT_PMU, &out_val);
• GUEST_ASSERT(probe && out_val == 1);
• sbi_impl_version = get_host_sbi_impl_version();
• if (sbi_impl_version >= sbi_mk_version(2, 0))

• __GUEST_ASSERT(0, "SBI implementation version doesn't support PMU Snapshot");
  

• 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 & (1UL << i))
  

BIT()

• 	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; @@ -328,6 +419,36 @@ 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) +{

• vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, PMU_SNAPSHOT_GPA_BASE, 1, 1, 0);
• /* PMU Snapshot requires single page only */

This comment should go above the memory region add

• virt_map(vm, PMU_SNAPSHOT_GPA_BASE, PMU_SNAPSHOT_GPA_BASE, 1);
• /* PMU_SNAPSHOT_GPA_BASE is identity mapped */

This comment should go above the virt_map

• 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 = NULL;

nit: no need to set to NULL

• vm = vm_create_with_one_vcpu(&vcpu, guest_code);
• __TEST_REQUIRE(__vcpu_has_ext(vcpu, RISCV_ISA_EXT_REG(KVM_RISCV_SBI_EXT_PMU)),

RISCV_SBI_EXT_REG

• 		   "SBI PMU not available, skipping test");
  

• test_vm_setup_snapshot_mem(vm, vcpu);
• vcpu_args_set(vcpu, 1, 0);

no need to set args

• run_vcpu(vcpu);
• test_vm_destroy(vm);

+}

int main(void) { test_vm_basic_test(test_pmu_basic_sanity); @@ -336,5 +457,8 @@ 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;

}

2.34.1

Thanks, drew