[PATCH v2] drivers/firmware: psci_checker: stash and use topology_core_cpumask for hotplug tests

[sudeep.holla@arm.com (Sudeep Holla)]

Commit 7f9545aa1a91 ("arm64: smp: remove cpu and numa topology
information when hotplugging out CPU") updates the cpu topology when
the CPU is hotplugged out. However the PSCI checker code uses the
topology_core_cpumask pointers for some of the cpu hotplug testing.
Since the pointer to the core_cpumask of the first CPU in the group
is used, which when that CPU itself is hotpugged out is just set to
itself, the testing terminates after that particular CPU is tested out.
But the intention of this tests is to cover all the CPU in the group.

In order to support that, we need to stash the topology_core_cpumask
before the start of the test and use that value instead of pointer to
a cpumask which will be updated on CPU hotplug.

Fixes: 7f9545aa1a91a9a4 ("arm64: smp: remove cpu and numa topology
	information when hotplugging out CPU")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/firmware/psci_checker.c | 53 ++++++++++++++++++++++++++++++++---------
 1 file changed, 42 insertions(+), 11 deletions(-)

v1->v2:
	- Move allocation and freeing of the cpumasks to separate
	  routines as suggested by Lorenzo
	- Reduced the allocation to number of groups instead of number
	  of cpus in the system by making 2 pass

diff --git a/drivers/firmware/psci_checker.c b/drivers/firmware/psci_checker.c
index bb1c068bff19..7e6f66b588fd 100644
--- a/drivers/firmware/psci_checker.c
+++ b/drivers/firmware/psci_checker.c
@@ -77,21 +77,23 @@ static int psci_ops_check(void)
 	return 0;
 }

-static int find_cpu_groups(const struct cpumask *cpus,
-			   const struct cpumask **cpu_groups)
+static int find_cpu_groups(cpumask_var_t *cpu_groups)
 {
 	unsigned int nb = 0;
 	cpumask_var_t tmp;

 	if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 		return -ENOMEM;
-	cpumask_copy(tmp, cpus);
+	cpumask_copy(tmp, cpu_online_mask);

 	while (!cpumask_empty(tmp)) {
 		const struct cpumask *cpu_group =
 			topology_core_cpumask(cpumask_any(tmp));

-		cpu_groups[nb++] = cpu_group;
+		if (cpu_groups && cpu_groups[nb])
+			cpumask_copy(cpu_groups[nb], cpu_group);
+
+		nb++;
 		cpumask_andnot(tmp, tmp, cpu_group);
 	}

@@ -166,20 +168,48 @@ static unsigned int down_and_up_cpus(const struct cpumask *cpus,
 	return err;
 }

+static void free_cpu_groups(int num, cpumask_var_t *cpu_groups)
+{
+	int i;
+
+	for (i = 0; i < num; ++i)
+		free_cpumask_var(cpu_groups[i]);
+	kfree(cpu_groups);
+}
+
+static cpumask_var_t *alloc_cpu_groups(int num)
+{
+	int i;
+	cpumask_var_t *cpu_groups;
+
+	cpu_groups = kcalloc(num, sizeof(cpu_groups), GFP_KERNEL);
+	if (!cpu_groups)
+		return NULL;
+
+	for (i = 0; i < num; ++i)
+		if (!alloc_cpumask_var(&cpu_groups[i], GFP_KERNEL)) {
+			free_cpu_groups(num, cpu_groups);
+			return NULL;
+		}
+
+	return cpu_groups;
+}
+
 static int hotplug_tests(void)
 {
 	int err;
-	cpumask_var_t offlined_cpus;
+	cpumask_var_t offlined_cpus, *cpu_groups;
 	int i, nb_cpu_group;
-	const struct cpumask **cpu_groups;
 	char *page_buf;

+	/* first run to just get the number of cpu groups */
+	nb_cpu_group = find_cpu_groups(NULL);
+
 	err = -ENOMEM;
 	if (!alloc_cpumask_var(&offlined_cpus, GFP_KERNEL))
 		return err;
-	/* We may have up to nb_available_cpus cpu_groups. */
-	cpu_groups = kmalloc_array(nb_available_cpus, sizeof(*cpu_groups),
-				   GFP_KERNEL);
+
+	cpu_groups = alloc_cpu_groups(nb_cpu_group);
 	if (!cpu_groups)
 		goto out_free_cpus;
 	page_buf = (char *)__get_free_page(GFP_KERNEL);
@@ -187,7 +217,8 @@ static int hotplug_tests(void)
 		goto out_free_cpu_groups;

 	err = 0;
-	nb_cpu_group = find_cpu_groups(cpu_online_mask, cpu_groups);
+	/* second run to populate/copy the cpumask */
+	nb_cpu_group = find_cpu_groups(cpu_groups);

 	/*
 	 * Of course the last CPU cannot be powered down and cpu_down() should
@@ -212,7 +243,7 @@ static int hotplug_tests(void)

 	free_page((unsigned long)page_buf);
 out_free_cpu_groups:
-	kfree(cpu_groups);
+	free_cpu_groups(nb_cpu_group, cpu_groups);
 out_free_cpus:
 	free_cpumask_var(offlined_cpus);
 	return err;
--
2.7.4