[kvm-unit-tests GIT PULL 03/11] s390x: smp: add tests for calls in wait state

Janosch Frank
2022-09-20T07:37:13Z

When the SIGP interpretation facility is in use a SIGP external call to
a waiting CPU will result in an exit of the calling cpu. For non-pv
guests it's a code 56 (partial execution) exit otherwise its a code 108
(secure instruction notification) exit. Those exits are handled
differently from a normal SIGP instruction intercept that happens
without interpretation and hence need to be tested.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20220810074616.1223561-4-nrb@linux.ibm.com
Message-Id: <20220810074616.1223561-4-nrb@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
s390x/smp.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 97 insertions(+)

diff --git a/s390x/smp.c b/s390x/smp.c
index 5a269087..91f3e3bc 100644
--- a/s390x/smp.c
+++ b/s390x/smp.c
@@ -356,6 +356,102 @@ static void test_calls(void)
}
}

+static void call_in_wait_ext_int_fixup(struct stack_frame_int *stack)
+{
+ /* Clear wait bit so we don't immediately wait again after the fixup */
+ lowcore.ext_old_psw.mask &= ~PSW_MASK_WAIT;
+}
+
+static void call_in_wait_setup(void)
+{
+ expect_ext_int();
+ ctl_set_bit(0, current_sigp_call_case->cr0_bit);
+ register_ext_cleanup_func(call_in_wait_ext_int_fixup);
+
+ 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_cleanup(void)
+{
+ ctl_clear_bit(0, current_sigp_call_case->cr0_bit);
+ register_ext_cleanup_func(NULL);
+
+ set_flag(1);
+}
+
+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;
+ }
+
+ /* Let the secondary CPU setup the external mask and the external interrupt cleanup function */
+ set_flag(0);
+ psw.mask = extract_psw_mask();
+ psw.addr = (unsigned long)call_in_wait_setup;
+ smp_cpu_start(1, psw);
+
+ /* Wait until the receiver has finished setup */
+ wait_for_flag();
+ set_flag(0);
+
+ /*
+ * 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);
+ 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 until the receiver has handled the call */
+ wait_for_flag();
+ smp_cpu_stop(1);
+ set_flag(0);
+
+ /*
+ * Now clean up the mess we have left behind. If the cleanup
+ * were part of call_in_wait_received we would not get a chance
+ * to catch an interrupt that is presented twice since we would
+ * disable the external call on the first interrupt.
+ */
+ psw.mask = extract_psw_mask();
+ psw.addr = (unsigned long)call_in_wait_cleanup;
+ smp_cpu_start(1, psw);
+
+ /* Wait until the cleanup has been completed */
+ wait_for_flag();
+ smp_cpu_stop(1);
+
+ report_prefix_pop();
+ }
+ report_prefix_pop();
+}
+
static void test_sense_running(void)
{
report_prefix_push("sense_running");
@@ -474,6 +570,7 @@ int main(void)
test_store_status();
test_set_prefix();
test_calls();
+ test_calls_in_wait();
test_sense_running();
test_reset();
test_reset_initial();
--
2.34.1