KVM: riscv: selftests: Add SBI PMU selftest

This test implements basic sanity test and cycle/instret event
counting tests.

Reviewed-by: Anup Patel <[e-mail]>
Reviewed-by: Andrew Jones <[e-mail]>
Signed-off-by: Atish Patra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Anup Patel <[e-mail]>

tools/testing/selftests/kvm/Makefile

···
 TEST_GEN_PROGS_s390x += set_memory_region_test
 TEST_GEN_PROGS_s390x += kvm_binary_stats_test
 
+TEST_GEN_PROGS_riscv += riscv/sbi_pmu_test
 TEST_GEN_PROGS_riscv += riscv/ebreak_test
 TEST_GEN_PROGS_riscv += arch_timer
 TEST_GEN_PROGS_riscv += demand_paging_test

tools/testing/selftests/kvm/riscv/sbi_pmu_test.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sbi_pmu_test.c - Tests the riscv64 SBI PMU functionality.
+ *
+ * Copyright (c) 2024, Rivos Inc.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include "kvm_util.h"
+#include "test_util.h"
+#include "processor.h"
+#include "sbi.h"
+
+/* Maximum counters(firmware + hardware) */
+#define RISCV_MAX_PMU_COUNTERS 64
+union sbi_pmu_ctr_info ctrinfo_arr[RISCV_MAX_PMU_COUNTERS];
+
+/* Cache the available counters in a bitmask */
+static unsigned long counter_mask_available;
+
+static bool illegal_handler_invoked;
+
+unsigned long pmu_csr_read_num(int csr_num)
+{
+#define switchcase_csr_read(__csr_num, __val)		{\
+	case __csr_num:					\
+		__val = csr_read(__csr_num);		\
+		break; }
+#define switchcase_csr_read_2(__csr_num, __val)		{\
+	switchcase_csr_read(__csr_num + 0, __val)	 \
+	switchcase_csr_read(__csr_num + 1, __val)}
+#define switchcase_csr_read_4(__csr_num, __val)		{\
+	switchcase_csr_read_2(__csr_num + 0, __val)	 \
+	switchcase_csr_read_2(__csr_num + 2, __val)}
+#define switchcase_csr_read_8(__csr_num, __val)		{\
+	switchcase_csr_read_4(__csr_num + 0, __val)	 \
+	switchcase_csr_read_4(__csr_num + 4, __val)}
+#define switchcase_csr_read_16(__csr_num, __val)	{\
+	switchcase_csr_read_8(__csr_num + 0, __val)	 \
+	switchcase_csr_read_8(__csr_num + 8, __val)}
+#define switchcase_csr_read_32(__csr_num, __val)	{\
+	switchcase_csr_read_16(__csr_num + 0, __val)	 \
+	switchcase_csr_read_16(__csr_num + 16, __val)}
+
+	unsigned long ret = 0;
+
+	switch (csr_num) {
+	switchcase_csr_read_32(CSR_CYCLE, ret)
+	switchcase_csr_read_32(CSR_CYCLEH, ret)
+	default :
+		break;
+	}
+
+	return ret;
+#undef switchcase_csr_read_32
+#undef switchcase_csr_read_16
+#undef switchcase_csr_read_8
+#undef switchcase_csr_read_4
+#undef switchcase_csr_read_2
+#undef switchcase_csr_read
+}
+
+static inline void dummy_func_loop(uint64_t iter)
+{
+	int i = 0;
+
+	while (i < iter) {
+		asm volatile("nop");
+		i++;
+	}
+}
+
+static void start_counter(unsigned long counter, unsigned long start_flags,
+			  unsigned long ival)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, counter, 1, start_flags,
+			ival, 0, 0);
+	__GUEST_ASSERT(ret.error == 0, "Unable to start counter %ld\n", counter);
+}
+
+/* This should be invoked only for reset counter use case */
+static void stop_reset_counter(unsigned long counter, unsigned long stop_flags)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, counter, 1,
+					stop_flags | SBI_PMU_STOP_FLAG_RESET, 0, 0, 0);
+	__GUEST_ASSERT(ret.error == SBI_ERR_ALREADY_STOPPED,
+			       "Unable to stop counter %ld\n", counter);
+}
+
+static void stop_counter(unsigned long counter, unsigned long stop_flags)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, counter, 1, stop_flags,
+			0, 0, 0);
+	__GUEST_ASSERT(ret.error == 0, "Unable to stop counter %ld error %ld\n",
+			       counter, ret.error);
+}
+
+static void guest_illegal_exception_handler(struct ex_regs *regs)
+{
+	__GUEST_ASSERT(regs->cause == EXC_INST_ILLEGAL,
+		       "Unexpected exception handler %lx\n", regs->cause);
+
+	illegal_handler_invoked = true;
+	/* skip the trapping instruction */
+	regs->epc += 4;
+}
+
+static unsigned long get_counter_index(unsigned long cbase, unsigned long cmask,
+				       unsigned long cflags,
+				       unsigned long event)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
+			cflags, event, 0, 0);
+	__GUEST_ASSERT(ret.error == 0, "config matching failed %ld\n", ret.error);
+	GUEST_ASSERT(ret.value < RISCV_MAX_PMU_COUNTERS);
+	GUEST_ASSERT(BIT(ret.value) & counter_mask_available);
+
+	return ret.value;
+}
+
+static unsigned long get_num_counters(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
+
+	__GUEST_ASSERT(ret.error == 0, "Unable to retrieve number of counters from SBI PMU");
+	__GUEST_ASSERT(ret.value < RISCV_MAX_PMU_COUNTERS,
+		       "Invalid number of counters %ld\n", ret.value);
+
+	return ret.value;
+}
+
+static void update_counter_info(int num_counters)
+{
+	int i = 0;
+	struct sbiret ret;
+
+	for (i = 0; i < num_counters; i++) {
+		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
+
+		/* There can be gaps in logical counter indicies*/
+		if (ret.error)
+			continue;
+		GUEST_ASSERT_NE(ret.value, 0);
+
+		ctrinfo_arr[i].value = ret.value;
+		counter_mask_available |= BIT(i);
+	}
+
+	GUEST_ASSERT(counter_mask_available > 0);
+}
+
+static unsigned long read_fw_counter(int idx, union sbi_pmu_ctr_info ctrinfo)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ, idx, 0, 0, 0, 0, 0);
+	GUEST_ASSERT(ret.error == 0);
+	return ret.value;
+}
+
+static unsigned long read_counter(int idx, union sbi_pmu_ctr_info ctrinfo)
+{
+	unsigned long counter_val = 0;
+
+	__GUEST_ASSERT(ctrinfo.type < 2, "Invalid counter type %d", ctrinfo.type);
+
+	if (ctrinfo.type == SBI_PMU_CTR_TYPE_HW)
+		counter_val = pmu_csr_read_num(ctrinfo.csr);
+	else if (ctrinfo.type == SBI_PMU_CTR_TYPE_FW)
+		counter_val = read_fw_counter(idx, ctrinfo);
+
+	return counter_val;
+}
+
+static void test_pmu_event(unsigned long event)
+{
+	unsigned long counter;
+	unsigned long counter_value_pre, counter_value_post;
+	unsigned long counter_init_value = 100;
+
+	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, 0);
+
+	counter_value_post = read_counter(counter, ctrinfo_arr[counter]);
+	__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.
+	 */
+	start_counter(counter, SBI_PMU_START_FLAG_SET_INIT_VALUE, ULONG_MAX/2);
+	stop_counter(counter, 0);
+	counter_value_pre = read_counter(counter, ctrinfo_arr[counter]);
+
+	start_counter(counter, SBI_PMU_START_FLAG_SET_INIT_VALUE, counter_init_value);
+	stop_counter(counter, 0);
+	counter_value_post = read_counter(counter, ctrinfo_arr[counter]);
+	__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 */
+	start_counter(counter, SBI_PMU_START_FLAG_SET_INIT_VALUE, counter_init_value);
+	dummy_func_loop(10000);
+	stop_counter(counter, 0);
+
+	counter_value_post = read_counter(counter, ctrinfo_arr[counter]);
+	__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;
+	unsigned long event = 0x1234; /* A random event */
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, 0,
+			counter_mask_available, 0, event, 0, 0);
+	GUEST_ASSERT_EQ(ret.error, SBI_ERR_NOT_SUPPORTED);
+}
+
+static void test_pmu_events(void)
+{
+	int num_counters = 0;
+
+	/* Get the counter details */
+	num_counters = get_num_counters();
+	update_counter_info(num_counters);
+
+	/* Sanity testing for any random invalid event */
+	test_invalid_event();
+
+	/* Only these two events are guaranteed to be present */
+	test_pmu_event(SBI_PMU_HW_CPU_CYCLES);
+	test_pmu_event(SBI_PMU_HW_INSTRUCTIONS);
+
+	GUEST_DONE();
+}
+
+static void test_pmu_basic_sanity(void)
+{
+	long out_val = 0;
+	bool probe;
+	struct sbiret ret;
+	int num_counters = 0, i;
+	union sbi_pmu_ctr_info ctrinfo;
+
+	probe = guest_sbi_probe_extension(SBI_EXT_PMU, &out_val);
+	GUEST_ASSERT(probe && out_val == 1);
+
+	num_counters = get_num_counters();
+
+	for (i = 0; i < num_counters; i++) {
+		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i,
+				0, 0, 0, 0, 0);
+
+		/* There can be gaps in logical counter indicies*/
+		if (ret.error)
+			continue;
+		GUEST_ASSERT_NE(ret.value, 0);
+
+		ctrinfo.value = ret.value;
+
+		/**
+		 * Accessibility check of hardware and read capability of firmware counters.
+		 * The spec doesn't mandate any initial value. No need to check any value.
+		 */
+		if (ctrinfo.type == SBI_PMU_CTR_TYPE_HW) {
+			pmu_csr_read_num(ctrinfo.csr);
+			GUEST_ASSERT(illegal_handler_invoked);
+		} else if (ctrinfo.type == SBI_PMU_CTR_TYPE_FW) {
+			read_fw_counter(i, ctrinfo);
+		}
+	}
+
+	GUEST_DONE();
+}
+
+static void run_vcpu(struct kvm_vcpu *vcpu)
+{
+	struct ucall uc;
+
+	vcpu_run(vcpu);
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+		break;
+	case UCALL_DONE:
+	case UCALL_SYNC:
+		break;
+	default:
+		TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		break;
+	}
+}
+
+void test_vm_destroy(struct kvm_vm *vm)
+{
+	memset(ctrinfo_arr, 0, sizeof(union sbi_pmu_ctr_info) * RISCV_MAX_PMU_COUNTERS);
+	counter_mask_available = 0;
+	kvm_vm_free(vm);
+}
+
+static void test_vm_basic_test(void *guest_code)
+{
+	struct kvm_vm *vm;
+	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");
+	vm_init_vector_tables(vm);
+	/* Illegal instruction handler is required to verify read access without configuration */
+	vm_install_exception_handler(vm, EXC_INST_ILLEGAL, guest_illegal_exception_handler);
+
+	vcpu_init_vector_tables(vcpu);
+	run_vcpu(vcpu);
+
+	test_vm_destroy(vm);
+}
+
+static void test_vm_events_test(void *guest_code)
+{
+	struct kvm_vm *vm = NULL;
+	struct kvm_vcpu *vcpu = NULL;
+
+	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");
+	run_vcpu(vcpu);
+
+	test_vm_destroy(vm);
+}
+
+int main(void)
+{
+	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");
+
+	return 0;
+}