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arm_mpam: resctrl: Add kunit test for control format conversions

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resctrl specifies the format of the control schemes, and these don't match
the hardware.

Some of the conversions are a bit hairy - add some kunit tests.

Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Punit Agrawal <punit.agrawal@oss.qualcomm.com>
Tested-by: Jesse Chick <jessechick@os.amperecomputing.com>
Reviewed-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
[morse: squashed enough of Dave's fixes in here that it's his patch now!]
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
This commit is contained in:
Dave Martin 2026-03-13 14:46:03 +00:00 committed by James Morse
parent 36528c7681
commit 5dc8f73eaa
2 changed files with 319 additions and 0 deletions
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4
drivers/resctrl/mpam_resctrl.c
View File

@ -1092,3 +1092,7 @@ static int __init __cacheinfo_ready(void)
return 0;
}
device_initcall_sync(__cacheinfo_ready);
#ifdef CONFIG_MPAM_KUNIT_TEST
#include "test_mpam_resctrl.c"
#endif

315
drivers/resctrl/test_mpam_resctrl.c Normal file
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@ -0,0 +1,315 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2025 Arm Ltd.
/* This file is intended to be included into mpam_resctrl.c */
#include <kunit/test.h>
#include <linux/array_size.h>
#include <linux/bits.h>
#include <linux/math.h>
#include <linux/sprintf.h>
struct percent_value_case {
u8 pc;
u8 width;
u16 value;
};
/*
* Mysterious inscriptions taken from the union of ARM DDI 0598D.b,
* "Arm Architecture Reference Manual Supplement - Memory System
* Resource Partitioning and Monitoring (MPAM), for A-profile
* architecture", Section 9.8, "About the fixed-point fractional
* format" (exact percentage entries only) and ARM IHI0099B.a
* "MPAM system component specification", Section 9.3,
* "The fixed-point fractional format":
*/
static const struct percent_value_case percent_value_cases[] = {
/* Architectural cases: */
{ 1, 8, 1 }, { 1, 12, 0x27 }, { 1, 16, 0x28e },
{ 25, 8, 0x3f }, { 25, 12, 0x3ff }, { 25, 16, 0x3fff },
{ 33, 8, 0x53 }, { 33, 12, 0x546 }, { 33, 16, 0x5479 },
{ 35, 8, 0x58 }, { 35, 12, 0x598 }, { 35, 16, 0x5998 },
{ 45, 8, 0x72 }, { 45, 12, 0x732 }, { 45, 16, 0x7332 },
{ 50, 8, 0x7f }, { 50, 12, 0x7ff }, { 50, 16, 0x7fff },
{ 52, 8, 0x84 }, { 52, 12, 0x850 }, { 52, 16, 0x851d },
{ 55, 8, 0x8b }, { 55, 12, 0x8cb }, { 55, 16, 0x8ccb },
{ 58, 8, 0x93 }, { 58, 12, 0x946 }, { 58, 16, 0x9479 },
{ 75, 8, 0xbf }, { 75, 12, 0xbff }, { 75, 16, 0xbfff },
{ 80, 8, 0xcb }, { 80, 12, 0xccb }, { 80, 16, 0xcccb },
{ 88, 8, 0xe0 }, { 88, 12, 0xe13 }, { 88, 16, 0xe146 },
{ 95, 8, 0xf2 }, { 95, 12, 0xf32 }, { 95, 16, 0xf332 },
{ 100, 8, 0xff }, { 100, 12, 0xfff }, { 100, 16, 0xffff },
};
static void test_percent_value_desc(const struct percent_value_case *param,
char *desc)
{
snprintf(desc, KUNIT_PARAM_DESC_SIZE,
"pc=%d, width=%d, value=0x%.*x\n",
param->pc, param->width,
DIV_ROUND_UP(param->width, 4), param->value);
}
KUNIT_ARRAY_PARAM(test_percent_value, percent_value_cases,
test_percent_value_desc);
struct percent_value_test_info {
u32 pc; /* result of value-to-percent conversion */
u32 value; /* result of percent-to-value conversion */
u32 max_value; /* maximum raw value allowed by test params */
unsigned int shift; /* promotes raw testcase value to 16 bits */
};
/*
* Convert a reference percentage to a fixed-point MAX value and
* vice-versa, based on param (not test->param_value!)
*/
static void __prepare_percent_value_test(struct kunit *test,
struct percent_value_test_info *res,
const struct percent_value_case *param)
{
struct mpam_props fake_props = { };
/* Reject bogus test parameters that would break the tests: */
KUNIT_ASSERT_GE(test, param->width, 1);
KUNIT_ASSERT_LE(test, param->width, 16);
KUNIT_ASSERT_LT(test, param->value, 1 << param->width);
mpam_set_feature(mpam_feat_mbw_max, &fake_props);
fake_props.bwa_wd = param->width;
res->shift = 16 - param->width;
res->max_value = GENMASK_U32(param->width - 1, 0);
res->value = percent_to_mbw_max(param->pc, &fake_props);
res->pc = mbw_max_to_percent(param->value << res->shift, &fake_props);
}
static void test_get_mba_granularity(struct kunit *test)
{
int ret;
struct mpam_props fake_props = { };
/* Use MBW_MAX */
mpam_set_feature(mpam_feat_mbw_max, &fake_props);
fake_props.bwa_wd = 0;
KUNIT_EXPECT_FALSE(test, mba_class_use_mbw_max(&fake_props));
fake_props.bwa_wd = 1;
KUNIT_EXPECT_TRUE(test, mba_class_use_mbw_max(&fake_props));
/* Architectural maximum: */
fake_props.bwa_wd = 16;
KUNIT_EXPECT_TRUE(test, mba_class_use_mbw_max(&fake_props));
/* No usable control... */
fake_props.bwa_wd = 0;
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 0);
fake_props.bwa_wd = 1;
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 50); /* DIV_ROUND_UP(100, 1 << 1)% = 50% */
fake_props.bwa_wd = 2;
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 25); /* DIV_ROUND_UP(100, 1 << 2)% = 25% */
fake_props.bwa_wd = 3;
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 13); /* DIV_ROUND_UP(100, 1 << 3)% = 13% */
fake_props.bwa_wd = 6;
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 2); /* DIV_ROUND_UP(100, 1 << 6)% = 2% */
fake_props.bwa_wd = 7;
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 1); /* DIV_ROUND_UP(100, 1 << 7)% = 1% */
/* Granularity saturates at 1% */
fake_props.bwa_wd = 16; /* architectural maximum */
ret = get_mba_granularity(&fake_props);
KUNIT_EXPECT_EQ(test, ret, 1); /* DIV_ROUND_UP(100, 1 << 16)% = 1% */
}
static void test_mbw_max_to_percent(struct kunit *test)
{
const struct percent_value_case *param = test->param_value;
struct percent_value_test_info res;
/*
* Since the reference values in percent_value_cases[] all
* correspond to exact percentages, round-to-nearest will
* always give the exact percentage back when the MPAM max
* value has precision of 0.5% or finer. (Always true for the
* reference data, since they all specify 8 bits or more of
* precision.
*
* So, keep it simple and demand an exact match:
*/
__prepare_percent_value_test(test, &res, param);
KUNIT_EXPECT_EQ(test, res.pc, param->pc);
}
static void test_percent_to_mbw_max(struct kunit *test)
{
const struct percent_value_case *param = test->param_value;
struct percent_value_test_info res;
__prepare_percent_value_test(test, &res, param);
KUNIT_EXPECT_GE(test, res.value, param->value << res.shift);
KUNIT_EXPECT_LE(test, res.value, (param->value + 1) << res.shift);
KUNIT_EXPECT_LE(test, res.value, res.max_value << res.shift);
/* No flexibility allowed for 0% and 100%! */
if (param->pc == 0)
KUNIT_EXPECT_EQ(test, res.value, 0);
if (param->pc == 100)
KUNIT_EXPECT_EQ(test, res.value, res.max_value << res.shift);
}
static const void *test_all_bwa_wd_gen_params(struct kunit *test, const void *prev,
char *desc)
{
uintptr_t param = (uintptr_t)prev;
if (param > 15)
return NULL;
param++;
snprintf(desc, KUNIT_PARAM_DESC_SIZE, "wd=%u\n", (unsigned int)param);
return (void *)param;
}
static unsigned int test_get_bwa_wd(struct kunit *test)
{
uintptr_t param = (uintptr_t)test->param_value;
KUNIT_ASSERT_GE(test, param, 1);
KUNIT_ASSERT_LE(test, param, 16);
return param;
}
static void test_mbw_max_to_percent_limits(struct kunit *test)
{
struct mpam_props fake_props = {0};
u32 max_value;
mpam_set_feature(mpam_feat_mbw_max, &fake_props);
fake_props.bwa_wd = test_get_bwa_wd(test);
max_value = GENMASK(15, 16 - fake_props.bwa_wd);
KUNIT_EXPECT_EQ(test, mbw_max_to_percent(max_value, &fake_props),
MAX_MBA_BW);
KUNIT_EXPECT_EQ(test, mbw_max_to_percent(0, &fake_props),
get_mba_min(&fake_props));
/*
* Rounding policy dependent 0% sanity-check:
* With round-to-nearest, the minimum mbw_max value really
* should map to 0% if there are at least 200 steps.
* (100 steps may be enough for some other rounding policies.)
*/
if (fake_props.bwa_wd >= 8)
KUNIT_EXPECT_EQ(test, mbw_max_to_percent(0, &fake_props), 0);
if (fake_props.bwa_wd < 8 &&
mbw_max_to_percent(0, &fake_props) == 0)
kunit_warn(test, "wd=%d: Testsuite/driver Rounding policy mismatch?",
fake_props.bwa_wd);
}
/*
* Check that converting a percentage to mbw_max and back again (or, as
* appropriate, vice-versa) always restores the original value:
*/
static void test_percent_max_roundtrip_stability(struct kunit *test)
{
struct mpam_props fake_props = {0};
unsigned int shift;
u32 pc, max, pc2, max2;
mpam_set_feature(mpam_feat_mbw_max, &fake_props);
fake_props.bwa_wd = test_get_bwa_wd(test);
shift = 16 - fake_props.bwa_wd;
/*
* Converting a valid value from the coarser scale to the finer
* scale and back again must yield the original value:
*/
if (fake_props.bwa_wd >= 7) {
/* More than 100 steps: only test exact pc values: */
for (pc = get_mba_min(&fake_props); pc <= MAX_MBA_BW; pc++) {
max = percent_to_mbw_max(pc, &fake_props);
pc2 = mbw_max_to_percent(max, &fake_props);
KUNIT_EXPECT_EQ(test, pc2, pc);
}
} else {
/* Fewer than 100 steps: only test exact mbw_max values: */
for (max = 0; max < 1 << 16; max += 1 << shift) {
pc = mbw_max_to_percent(max, &fake_props);
max2 = percent_to_mbw_max(pc, &fake_props);
KUNIT_EXPECT_EQ(test, max2, max);
}
}
}
static void test_percent_to_max_rounding(struct kunit *test)
{
const struct percent_value_case *param = test->param_value;
unsigned int num_rounded_up = 0, total = 0;
struct percent_value_test_info res;
for (param = percent_value_cases, total = 0;
param < &percent_value_cases[ARRAY_SIZE(percent_value_cases)];
param++, total++) {
__prepare_percent_value_test(test, &res, param);
if (res.value > param->value << res.shift)
num_rounded_up++;
}
/*
* The MPAM driver applies a round-to-nearest policy, whereas a
* round-down policy seems to have been applied in the
* reference table from which the test vectors were selected.
*
* For a large and well-distributed suite of test vectors,
* about half should be rounded up and half down compared with
* the reference table. The actual test vectors are few in
* number and probably not very well distributed however, so
* tolerate a round-up rate of between 1/4 and 3/4 before
* crying foul:
*/
kunit_info(test, "Round-up rate: %u%% (%u/%u)\n",
DIV_ROUND_CLOSEST(num_rounded_up * 100, total),
num_rounded_up, total);
KUNIT_EXPECT_GE(test, 4 * num_rounded_up, 1 * total);
KUNIT_EXPECT_LE(test, 4 * num_rounded_up, 3 * total);
}
static struct kunit_case mpam_resctrl_test_cases[] = {
KUNIT_CASE(test_get_mba_granularity),
KUNIT_CASE_PARAM(test_mbw_max_to_percent, test_percent_value_gen_params),
KUNIT_CASE_PARAM(test_percent_to_mbw_max, test_percent_value_gen_params),
KUNIT_CASE_PARAM(test_mbw_max_to_percent_limits, test_all_bwa_wd_gen_params),
KUNIT_CASE(test_percent_to_max_rounding),
KUNIT_CASE_PARAM(test_percent_max_roundtrip_stability,
test_all_bwa_wd_gen_params),
{}
};
static struct kunit_suite mpam_resctrl_test_suite = {
.name = "mpam_resctrl_test_suite",
.test_cases = mpam_resctrl_test_cases,
};
kunit_test_suites(&mpam_resctrl_test_suite);