arm_mpam: Add kunit test for bitmap reset

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>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 69 insertions, 0 deletions

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);