KVM: riscv: selftests: Allow number of interrupts to be configurable

It is helpful to vary the number of the LCOFI interrupts generated
by the overflow test. Allow additional argument for overflow test
to accommodate that. It can be easily cross-validated with
/proc/interrupts output in the host.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250303-kvm_pmu_improve-v2-4-41d177e45929@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>

Author: atishp04

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

@@ -39,8 +39,10 @@ static bool illegal_handler_invoked;
 #define SBI_PMU_TEST_SNAPSHOT	BIT(2)
 #define SBI_PMU_TEST_OVERFLOW	BIT(3)
 
+#define SBI_PMU_OVERFLOW_IRQNUM_DEFAULT 5
 struct test_args {
 	int disabled_tests;
+	int overflow_irqnum;
 };
 
 static struct test_args targs;
@@ -478,7 +480,7 @@ static void test_pmu_events_snaphost(void)
 
 static void test_pmu_events_overflow(void)
 {
-	int num_counters = 0;
+	int num_counters = 0, i = 0;
 
 	/* Verify presence of SBI PMU and minimum requrired SBI version */
 	verify_sbi_requirement_assert();
@@ -495,11 +497,15 @@ static void test_pmu_events_overflow(void)
 	 * Qemu supports overflow for cycle/instruction.
 	 * This test may fail on any platform that do not support overflow for these two events.
 	 */
-	test_pmu_event_overflow(SBI_PMU_HW_CPU_CYCLES);
-	GUEST_ASSERT_EQ(vcpu_shared_irq_count, 1);
+	for (i = 0; i < targs.overflow_irqnum; i++)
+		test_pmu_event_overflow(SBI_PMU_HW_CPU_CYCLES);
+	GUEST_ASSERT_EQ(vcpu_shared_irq_count, targs.overflow_irqnum);
+
+	vcpu_shared_irq_count = 0;
 
-	test_pmu_event_overflow(SBI_PMU_HW_INSTRUCTIONS);
-	GUEST_ASSERT_EQ(vcpu_shared_irq_count, 2);
+	for (i = 0; i < targs.overflow_irqnum; i++)
+		test_pmu_event_overflow(SBI_PMU_HW_INSTRUCTIONS);
+	GUEST_ASSERT_EQ(vcpu_shared_irq_count, targs.overflow_irqnum);
 
 	GUEST_DONE();
 }
@@ -621,8 +627,11 @@ static void test_vm_events_overflow(void *guest_code)
 
 static void test_print_help(char *name)
 {
-	pr_info("Usage: %s [-h] [-t <test name>]\n", name);
+	pr_info("Usage: %s [-h] [-t <test name>] [-n <number of LCOFI interrupt for overflow test>]\n",
+		name);
 	pr_info("\t-t: Test to run (default all). Available tests are 'basic', 'events', 'snapshot', 'overflow'\n");
+	pr_info("\t-n: Number of LCOFI interrupt to trigger for each event in overflow test (default: %d)\n",
+		SBI_PMU_OVERFLOW_IRQNUM_DEFAULT);
 	pr_info("\t-h: print this help screen\n");
 }
 
@@ -631,7 +640,9 @@ static bool parse_args(int argc, char *argv[])
 	int opt;
 	int temp_disabled_tests = SBI_PMU_TEST_BASIC | SBI_PMU_TEST_EVENTS | SBI_PMU_TEST_SNAPSHOT |
 				  SBI_PMU_TEST_OVERFLOW;
-	while ((opt = getopt(argc, argv, "ht:")) != -1) {
+	int overflow_interrupts = 0;
+
+	while ((opt = getopt(argc, argv, "ht:n:")) != -1) {
 		switch (opt) {
 		case 't':
 			if (!strncmp("basic", optarg, 5))
@@ -646,12 +657,24 @@ static bool parse_args(int argc, char *argv[])
 				goto done;
 			targs.disabled_tests = temp_disabled_tests;
 			break;
+		case 'n':
+			overflow_interrupts = atoi_positive("Number of LCOFI", optarg);
+			break;
 		case 'h':
 		default:
 			goto done;
 		}
 	}
 
+	if (overflow_interrupts > 0) {
+		if (targs.disabled_tests & SBI_PMU_TEST_OVERFLOW) {
+			pr_info("-n option is only available for overflow test\n");
+			goto done;
+		} else {
+			targs.overflow_irqnum = overflow_interrupts;
+		}
+	}
+
 	return true;
 done:
 	test_print_help(argv[0]);
@@ -661,6 +684,7 @@ static bool parse_args(int argc, char *argv[])
 int main(int argc, char *argv[])
 {
 	targs.disabled_tests = 0;
+	targs.overflow_irqnum = SBI_PMU_OVERFLOW_IRQNUM_DEFAULT;
 
 	if (!parse_args(argc, argv))
 		exit(KSFT_SKIP);