[kvm-unit-tests PATCH v5 2/2] arm/psci: Add PSCI CPU_OFF test case

[Alexandru Elisei <alexandru.elisei@xxxxxxx>]

From: Nikita Venkatesh <Nikita.Venkatesh@xxxxxxx>

The test uses the following method.

The primary CPU brings up all the secondary CPUs, which are held in a wait
loop. Once the primary releases the CPUs, each of the secondary CPUs
proceed to issue CPU_OFF.

The primary CPU then checks for the status of the individual CPU_OFF
request. There is a chance that some CPUs might return from the CPU_OFF
function call after the primary CPU has finished the scan. There is no
foolproof method to handle this, but the test tries its best to
eliminate these false positives by introducing an extra delay if all the
CPUs are reported offline after the initial scan.

Signed-off-by: Nikita Venkatesh <Nikita.Venkatesh@xxxxxxx>
[ Alex E: Skip CPU_OFF test if CPU_ON failed, drop cpu_off_success in
	  favour of checking AFFINITY_INFO, commit message tweaking ]
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---

Decided to drop Drew's Reviewed-by tag because the changes are not trivial
from the previous version.

 arm/psci.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 75 insertions(+), 5 deletions(-)

diff --git a/arm/psci.c b/arm/psci.c
index f7238f8e0bbd..7034d8ebe6e1 100644
--- a/arm/psci.c
+++ b/arm/psci.c
@@ -72,8 +72,9 @@ static bool psci_affinity_info_off(void)
 }
 
 static int cpu_on_ret[NR_CPUS];
-static cpumask_t cpu_on_ready, cpu_on_done;
+static cpumask_t cpu_on_ready, cpu_on_done, cpu_off_done;
 static volatile int cpu_on_start;
+static volatile int cpu_off_start;
 
 extern void secondary_entry(void);
 static void cpu_on_do_wake_target(void)
@@ -171,9 +172,71 @@ static bool psci_cpu_on_test(void)
 	return !failed;
 }
 
-int main(void)
+static void cpu_off_secondary_entry(void *data)
+{
+	int cpu = smp_processor_id();
+
+	while (!cpu_off_start)
+		cpu_relax();
+	cpumask_set_cpu(cpu, &cpu_off_done);
+	cpu_psci_cpu_die();
+}
+
+static bool psci_cpu_off_test(void)
+{
+	bool failed = false;
+	int i, count, cpu;
+
+	for_each_present_cpu(cpu) {
+		if (cpu == 0)
+			continue;
+		on_cpu_async(cpu, cpu_off_secondary_entry, NULL);
+	}
+
+	cpumask_set_cpu(0, &cpu_off_done);
+
+	cpu_off_start = 1;
+	report_info("waiting for the CPUs to be offlined...");
+	while (!cpumask_full(&cpu_off_done))
+		cpu_relax();
+
+	/* Allow all the other CPUs to complete the operation */
+	for (i = 0; i < 100; i++) {
+		mdelay(10);
+
+		count = 0;
+		for_each_present_cpu(cpu) {
+			if (cpu == 0)
+				continue;
+			if (psci_affinity_info(cpus[cpu], 0) != PSCI_0_2_AFFINITY_LEVEL_OFF)
+				count++;
+		}
+		if (count > 0)
+			continue;
+	}
+
+	/* Try to catch CPUs that return from CPU_OFF. */
+	if (count == 0)
+		mdelay(100);
+
+	for_each_present_cpu(cpu) {
+		if (cpu == 0)
+			continue;
+		if (cpu_idle(cpu)) {
+			report_info("CPU%d failed to be offlined", cpu);
+			if (psci_affinity_info(cpus[cpu], 0) == PSCI_0_2_AFFINITY_LEVEL_OFF)
+				report_info("AFFINITY_INFO incorrectly reports CPU%d as offline", cpu);
+			failed = true;
+		}
+	}
+
+	return !failed;
+}
+
+int main(int argc, char **argv)
 {
 	int ver = psci_invoke(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
+	bool cpu_on_success = true;
 
 	report_prefix_push("psci");
 
@@ -188,10 +251,17 @@ int main(void)
 	report(psci_affinity_info_on(), "affinity-info-on");
 	report(psci_affinity_info_off(), "affinity-info-off");
 
-	if (ERRATA(6c7a5dce22b3))
-		report(psci_cpu_on_test(), "cpu-on");
-	else
+	if (ERRATA(6c7a5dce22b3)) {
+		cpu_on_success = psci_cpu_on_test();
+		report(cpu_on_success, "cpu-on");
+	} else {
 		report_skip("Skipping unsafe cpu-on test. Set ERRATA_6c7a5dce22b3=y to enable.");
+	}
+
+	if (!cpu_on_success)
+		report_skip("Skipping cpu-off test because the cpu-on test failed");
+	else
+		report(psci_cpu_off_test(), "cpu-off");
 
 done:
 #if 0
-- 
2.39.0