[PATCH 32/33] arm_mpam: Add kunit test for bitmap reset

Ben Horgan
2025-11-07T12:38:16Z

From: James Morse <james.morse@arm.com>

The bitmap reset code has been a source of bugs. Add a unit test.

This currently has to be built in, as the rest of the driver is
builtin.

Suggested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
drivers/resctrl/Kconfig | 9 ++++
drivers/resctrl/mpam_devices.c | 4 ++
drivers/resctrl/test_mpam_devices.c | 69 +++++++++++++++++++++++++++++
3 files changed, 82 insertions(+)
create mode 100644 drivers/resctrl/test_mpam_devices.c

diff --git a/drivers/resctrl/Kconfig b/drivers/resctrl/Kconfig
index ef2f3adf64a9..6368376fa51d 100644
--- a/drivers/resctrl/Kconfig
+++ b/drivers/resctrl/Kconfig
@@ -12,4 +12,13 @@ config ARM64_MPAM_DRIVER_DEBUG
help
Say yes here to enable debug messages from the MPAM driver.

+config MPAM_KUNIT_TEST
+ bool "KUnit tests for MPAM driver " if !KUNIT_ALL_TESTS
+ depends on KUNIT=y
+ default KUNIT_ALL_TESTS
+ help
+ Enable this option to run tests in the MPAM driver.
+
+ If unsure, say N.
+
endif
diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index eb6417f57e23..b04050ad351a 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -2723,3 +2723,7 @@ static int __init mpam_msc_driver_init(void)

/* Must occur after arm64_mpam_register_cpus() from arch_initcall() */
subsys_initcall(mpam_msc_driver_init);
+
+#ifdef CONFIG_MPAM_KUNIT_TEST
+#include "test_mpam_devices.c"
+#endif
diff --git a/drivers/resctrl/test_mpam_devices.c b/drivers/resctrl/test_mpam_devices.c
new file mode 100644
index 000000000000..0cfb41b665c4
--- /dev/null
+++ b/drivers/resctrl/test_mpam_devices.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2025 Arm Ltd.
+/* This file is intended to be included into mpam_devices.c */
+
+#include <kunit/test.h>
+
+static void test_mpam_reset_msc_bitmap(struct kunit *test)
+{
+ char __iomem *buf = kunit_kzalloc(test, SZ_16K, GFP_KERNEL);
+ struct mpam_msc fake_msc = {};
+ u32 *test_result;
+
+ if (!buf)
+ return;
+
+ fake_msc.mapped_hwpage = buf;
+ fake_msc.mapped_hwpage_sz = SZ_16K;
+ cpumask_copy(&fake_msc.accessibility, cpu_possible_mask);
+
+ /* Satisfy lockdep checks */
+ mutex_init(&fake_msc.part_sel_lock);
+ mutex_lock(&fake_msc.part_sel_lock);
+
+ test_result = (u32 *)(buf + MPAMCFG_CPBM);
+
+ mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 0);
+ KUNIT_EXPECT_EQ(test, test_result[0], 0);
+ KUNIT_EXPECT_EQ(test, test_result[1], 0);
+ test_result[0] = 0;
+ test_result[1] = 0;
+
+ mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 1);
+ KUNIT_EXPECT_EQ(test, test_result[0], 1);
+ KUNIT_EXPECT_EQ(test, test_result[1], 0);
+ test_result[0] = 0;
+ test_result[1] = 0;
+
+ mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 16);
+ KUNIT_EXPECT_EQ(test, test_result[0], 0xffff);
+ KUNIT_EXPECT_EQ(test, test_result[1], 0);
+ test_result[0] = 0;
+ test_result[1] = 0;
+
+ mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 32);
+ KUNIT_EXPECT_EQ(test, test_result[0], 0xffffffff);
+ KUNIT_EXPECT_EQ(test, test_result[1], 0);
+ test_result[0] = 0;
+ test_result[1] = 0;
+
+ mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 33);
+ KUNIT_EXPECT_EQ(test, test_result[0], 0xffffffff);
+ KUNIT_EXPECT_EQ(test, test_result[1], 1);
+ test_result[0] = 0;
+ test_result[1] = 0;
+
+ mutex_unlock(&fake_msc.part_sel_lock);
+}
+
+static struct kunit_case mpam_devices_test_cases[] = {
+ KUNIT_CASE(test_mpam_reset_msc_bitmap),
+ {}
+};
+
+static struct kunit_suite mpam_devices_test_suite = {
+ .name = "mpam_devices_test_suite",
+ .test_cases = mpam_devices_test_cases,
+};
+
+kunit_test_suites(&mpam_devices_test_suite);
--
2.43.0