[PATCH v3 25/47] arm_mpam: resctrl: Add kunit test for rmid idx conversions

[Jonathan Cameron]

On Mon, 12 Jan 2026 16:58:52 +0000
Ben Horgan <ben.horgan at arm.com> wrote:

> As MPAM's pmg are scoped by partid and RDT's rmid are global the
> rescrl mapping to an index needs to differ.
> 
> Add some tests for the MPAM rmid mapping.
> 
> Signed-off-by: Ben Horgan <ben.horgan at arm.com>
I'm not sure this particular test brings a massive amount of value, but
I'm not one to object to more tests!

Reviewed-by: Jonathan Cameron <jonathan.cameron at huawei.com>

> ---
>  drivers/resctrl/test_mpam_resctrl.c | 49 +++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/drivers/resctrl/test_mpam_resctrl.c b/drivers/resctrl/test_mpam_resctrl.c
> index b93d6ad87e43..a20da161d965 100644
> --- a/drivers/resctrl/test_mpam_resctrl.c
> +++ b/drivers/resctrl/test_mpam_resctrl.c
> @@ -296,6 +296,54 @@ static void test_percent_to_max_rounding(struct kunit *test)
>  	KUNIT_EXPECT_LE(test, 4 * num_rounded_up, 3 * total);
>  }
>  
> +struct rmid_idx_case {
> +	u32 max_partid;
> +	u32 max_pmg;
> +};
> +
> +static const struct rmid_idx_case rmid_idx_cases[] = {
> +	{0, 0}, {1, 4}, {3, 1}, {5, 9}, {4, 4}, {100, 11}, {0xFFFF, 0xFF},
> +};
> +
> +static void test_rmid_idx_desc(const struct rmid_idx_case *param, char *desc)
> +{
> +	snprintf(desc, KUNIT_PARAM_DESC_SIZE, "max_partid=%d, max_pmg=%d\n",
> +		 param->max_partid, param->max_pmg);
> +}
> +
> +KUNIT_ARRAY_PARAM(test_rmid_idx, rmid_idx_cases, test_rmid_idx_desc);
> +
> +static void test_rmid_idx_encoding(struct kunit *test)
> +{
> +	u32 orig_mpam_partid_max = mpam_partid_max;
> +	u32 orig_mpam_pmg_max = mpam_pmg_max;
> +	const struct rmid_idx_case *param = test->param_value;
> +	u32 idx, num_idx, count = 0;
> +
> +	mpam_partid_max = param->max_partid;
> +	mpam_pmg_max = param->max_pmg;
> +
> +	for (u32 partid = 0; partid <= mpam_partid_max; partid++) {
> +		for (u32 pmg = 0; pmg <= mpam_pmg_max; pmg++) {
> +			u32 partid_out, pmg_out;
> +
> +			idx = resctrl_arch_rmid_idx_encode(partid, pmg);
> +			/* Confirm there are no holes in the rmid idx range */
> +			KUNIT_EXPECT_EQ(test, count, idx);
> +			count++;
> +			resctrl_arch_rmid_idx_decode(idx, &partid_out, &pmg_out);
> +			KUNIT_EXPECT_EQ(test, pmg, pmg_out);
> +			KUNIT_EXPECT_EQ(test, partid, partid_out);
> +		}
> +	}
> +	num_idx = resctrl_arch_system_num_rmid_idx();
> +	KUNIT_EXPECT_EQ(test, idx + 1, num_idx);
> +
> +	/* Restore global variables that were messed with */
> +	mpam_partid_max = orig_mpam_partid_max;
> +	mpam_pmg_max = orig_mpam_pmg_max;
> +}