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

[Ben Horgan <ben.horgan@arm.com>]

Hi James,

On 8/22/25 16:30, James Morse wrote:
> 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>
> ---
>  drivers/resctrl/Kconfig             | 13 ++++++
>  drivers/resctrl/mpam_devices.c      |  4 ++
>  drivers/resctrl/test_mpam_devices.c | 68 +++++++++++++++++++++++++++++
>  3 files changed, 85 insertions(+)
>  create mode 100644 drivers/resctrl/test_mpam_devices.c
> 
> diff --git a/drivers/resctrl/Kconfig b/drivers/resctrl/Kconfig
> index dff7b87280ab..f5e0609975e4 100644
> --- a/drivers/resctrl/Kconfig
> +++ b/drivers/resctrl/Kconfig
> @@ -4,8 +4,21 @@ config ARM64_MPAM_DRIVER
>  	bool "MPAM driver for System IP, e,g. caches and memory controllers"
>  	depends on ARM64_MPAM && EXPERT
>  
> +menu "ARM64 MPAM driver options"
> +
>  config ARM64_MPAM_DRIVER_DEBUG
>  	bool "Enable debug messages from the MPAM driver."
>  	depends on ARM64_MPAM_DRIVER
>  	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
It depends on ARM64_MPAM_DRIVER as well.

> +	default KUNIT_ALL_TESTS
> +	help
> +	  Enable this option to run tests in the MPAM driver.
> +
> +	  If unsure, say N.
> +
> +endmenu
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 65c30ebfe001..4cf5aae88c53 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -2903,3 +2903,7 @@ 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..8e9d6c88171c
> --- /dev/null
> +++ b/drivers/resctrl/test_mpam_devices.c
> @@ -0,0 +1,68 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2024 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 *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);
> +
> +	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);

Thanks,

Ben