[kvm-unit-tests PATCH v1 4/4] s390x: smp: add tests for calls in wait state

[Nico Boehr <nrb@linux.ibm.com>]

Under PV, SIGP ecall requires some special handling by the hypervisor
when the receiving CPU is in enabled wait. Hence, we should have
coverage for the various SIGP call orders when the receiving CPU is in
enabled wait.

The ecall test currently fails under PV due to a KVM bug under
investigation.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 s390x/smp.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/s390x/smp.c b/s390x/smp.c
index 857eae206daa..2b48f83d2b6d 100644
--- a/s390x/smp.c
+++ b/s390x/smp.c
@@ -350,6 +350,79 @@ static void test_calls(void)
 	}
 }
 
+static void call_in_wait_setup(void)
+{
+	expect_ext_int();
+	ctl_set_bit(0, current_sigp_call_case->cr0_bit);
+	set_flag(1);
+}
+
+static void call_in_wait_received(void)
+{
+	report(lowcore.ext_int_code == current_sigp_call_case->ext_int_expected_type, "received");
+	set_flag(1);
+}
+
+static void call_in_wait_ext_int_fixup(struct stack_frame_int *stack)
+{
+	/* leave wait after returning */
+	lowcore.ext_old_psw.mask &= ~PSW_MASK_WAIT;
+
+	stack->crs[0] &= ~current_sigp_call_case->cr0_bit;
+}
+
+static void test_calls_in_wait(void)
+{
+	int i;
+	struct psw psw;
+
+	report_prefix_push("psw wait");
+	for (i = 0; i < ARRAY_SIZE(cases_sigp_call); i++) {
+		current_sigp_call_case = &cases_sigp_call[i];
+
+		report_prefix_push(current_sigp_call_case->name);
+		if (!current_sigp_call_case->supports_pv && uv_os_is_guest()) {
+			report_skip("Not supported under PV");
+			report_prefix_pop();
+			continue;
+		}
+
+		set_flag(0);
+		psw.mask = extract_psw_mask();
+		psw.addr = (unsigned long)call_in_wait_setup;
+		smp_cpu_start(1, psw);
+		wait_for_flag();
+		set_flag(0);
+
+		register_ext_cleanup_func(call_in_wait_ext_int_fixup);
+
+		/*
+		 * To avoid races, we need to know that the secondary CPU has entered wait,
+		 * but the architecture provides no way to check whether the secondary CPU
+		 * is in wait.
+		 *
+		 * But since a waiting CPU is considered operating, simply stop the CPU, set
+		 * up the restart new PSW mask in wait, send the restart interrupt and then
+		 * wait until the CPU becomes operating (done by smp_cpu_start).
+		 */
+		smp_cpu_stop(1);
+		expect_ext_int();
+		psw.mask = extract_psw_mask() | PSW_MASK_EXT | PSW_MASK_WAIT;
+		psw.addr = (unsigned long)call_in_wait_received;
+		smp_cpu_start(1, psw);
+
+		smp_sigp(1, current_sigp_call_case->call, 0, NULL);
+
+		wait_for_flag();
+		smp_cpu_stop(1);
+
+		register_ext_cleanup_func(NULL);
+
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+}
+
 static void test_sense_running(void)
 {
 	report_prefix_push("sense_running");
@@ -472,6 +545,7 @@ int main(void)
 	test_store_status();
 	test_set_prefix();
 	test_calls();
+	test_calls_in_wait();
 	test_sense_running();
 	test_reset();
 	test_reset_initial();
-- 
2.35.3