[kvm-unit-tests PATCH v4 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 PSCI_CPU_OFF. This is indicated by a cpumask and also the
status of the call is updated by the secondary CPU in cpu_off_done[].

The primary CPU waits for all the secondary CPUs to update the cpumask and
then proceeds to check for the status of the individual CPU CPU_OFF
request. There is a chance that some CPUs might fail at the CPU_OFF request
and come back and update the status once the primary CPU has finished the
scan. There is no fool proof method to handle this. As of now, we add a
1sec delay between the cpumask check and the scan for the status.

Signed-off-by: Nikita Venkatesh <Nikita.Venkatesh@xxxxxxx>
[ Alex E: Skip CPU_OFF test if CPU_ON failed ]
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
 arm/psci.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 66 insertions(+), 5 deletions(-)

diff --git a/arm/psci.c b/arm/psci.c
index e96be941953b..d045616bfcd4 100644
--- a/arm/psci.c
+++ b/arm/psci.c
@@ -15,6 +15,8 @@
 #include <asm/psci.h>
 #include <asm/smp.h>
 
+#define CPU_OFF_TEST_WAIT_TIME 1000
+
 static bool invalid_function_exception;
 
 #ifdef __arm__
@@ -71,8 +73,10 @@ static bool psci_affinity_info_off(void)
 }
 
 static int cpu_on_ret[NR_CPUS];
-static cpumask_t cpu_on_ready, cpu_on_done;
+static bool cpu_off_success[NR_CPUS];
+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)
@@ -94,6 +98,20 @@ static void cpu_on_target(void)
 	cpumask_set_cpu(cpu, &cpu_on_done);
 }
 
+static void cpu_off_secondary_entry(void *data)
+{
+	int cpu = smp_processor_id();
+
+	while (!cpu_off_start)
+		cpu_relax();
+	/* On to the CPU off test */
+	cpu_off_success[cpu] = true;
+	cpumask_set_cpu(cpu, &cpu_off_done);
+	cpu_psci_cpu_die();
+	/* The CPU shouldn't execute the next steps. */
+	cpu_off_success[cpu] = false;
+}
+
 static bool psci_cpu_on_test(void)
 {
 	bool failed = false;
@@ -162,9 +180,45 @@ out:
 	return !failed;
 }
 
-int main(void)
+static bool psci_cpu_off_test(void)
+{
+	bool failed = false;
+	int 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);
+
+	report_info("starting CPU_OFF test...");
+
+	cpu_off_start = 1;
+	while (!cpumask_full(&cpu_off_done))
+		cpu_relax();
+
+	/* Allow all the other CPUs to complete the operation */
+	mdelay(CPU_OFF_TEST_WAIT_TIME);
+
+	for_each_present_cpu(cpu) {
+		if (cpu == 0)
+			continue;
+
+		if (!cpu_off_success[cpu]) {
+			report_info("CPU%d could not be turned off", 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");
 
@@ -179,10 +233,17 @@ 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
-- 
2.25.1