[PATCH kvm-unit-tests v1 3/6] s390x: smp: Fix checks for SIGP STOP STORE STATUS

Eric Farman
2022-03-03T21:04:37Z

In the routine test_stop_store_status(), the "running" part of
the test checks a few of the fields in lowcore (to verify the
"STORE STATUS" part of the SIGP order), and then ensures that
the CPU has stopped. But this is backwards, and leads to false
errors.

According to the Principles of Operation:
The addressed CPU performs the stop function, fol-
lowed by the store-status operation (see “Store Sta-
tus” on page 4-82).

By checking the results how they are today, the contents of
the lowcore fields are unreliable until the CPU is stopped.
Thus, check that the CPU is stopped first, before ensuring
that the STORE STATUS was performed correctly.

While here, add the same check to the second part of the test,
even though the CPU is explicitly stopped prior to the SIGP.

Fixes: fc67b07a4 ("s390x: smp: Test stop and store status on a running and stopped cpu")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
s390x/smp.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/s390x/smp.c b/s390x/smp.c
index 2f4af820..50811bd0 100644
--- a/s390x/smp.c
+++ b/s390x/smp.c
@@ -98,9 +98,9 @@ static void test_stop_store_status(void)
lc->grs_sa[15] = 0;
smp_cpu_stop_store_status(1);
mb();
+ report(smp_cpu_stopped(1), "cpu stopped");
report(lc->prefix_sa == (uint32_t)(uintptr_t)cpu->lowcore, "prefix");
report(lc->grs_sa[15], "stack");
- report(smp_cpu_stopped(1), "cpu stopped");
report_prefix_pop();

report_prefix_push("stopped");
@@ -108,6 +108,7 @@ static void test_stop_store_status(void)
lc->grs_sa[15] = 0;
smp_cpu_stop_store_status(1);
mb();
+ report(smp_cpu_stopped(1), "cpu stopped");
report(lc->prefix_sa == (uint32_t)(uintptr_t)cpu->lowcore, "prefix");
report(lc->grs_sa[15], "stack");
report_prefix_pop();
--
2.32.0