[PATCH v2 31/45] arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions
From: Ben Horgan <ben.horgan@arm.com>
Date: 2025-12-19 18:14:31
Also in:
kvmarm, lkml
Subsystem:
mpam driver, the rest · Maintainers:
James Morse, Ben Horgan, Linus Torvalds
From: James Morse <james.morse@arm.com> ABMC exposes a fun corner case where a platform with one monitor can use ABMC for assignable counters - but not when CDP is enabled. Add some tests. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/test_mpam_resctrl.c | 62 +++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+)
diff --git a/drivers/resctrl/test_mpam_resctrl.c b/drivers/resctrl/test_mpam_resctrl.c
index d0615aa7671c..c83d54f21fa0 100644
--- a/drivers/resctrl/test_mpam_resctrl.c
+++ b/drivers/resctrl/test_mpam_resctrl.c@@ -293,6 +293,67 @@ static void test_percent_to_max_rounding(struct kunit *test) KUNIT_EXPECT_LE(test, 4 * num_rounded_up, 3 * total); } +static void test_num_assignable_counters(struct kunit *test) +{ + unsigned int orig_l3_num_allocated_mbwu = l3_num_allocated_mbwu; + u32 orig_mpam_partid_max = mpam_partid_max; + u32 orig_mpam_pmg_max = mpam_pmg_max; + bool orig_cdp_enabled = cdp_enabled; + struct rdt_resource fake_l3; + + /* Force there to be some PARTID/PMG */ + mpam_partid_max = 3; + mpam_pmg_max = 1; + + cdp_enabled = false; + + /* ABMC off, CDP off */ + l3_num_allocated_mbwu = resctrl_arch_system_num_rmid_idx(); + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, resctrl_arch_system_num_rmid_idx()); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_assign_on_mkdir); + + /* ABMC on, CDP off */ + l3_num_allocated_mbwu = 4; + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, 4); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_assign_on_mkdir); + + cdp_enabled = true; + + /* ABMC off, CDP on */ + l3_num_allocated_mbwu = resctrl_arch_system_num_rmid_idx(); + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + + /* (value not consumed by resctrl) */ + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, resctrl_arch_system_num_rmid_idx() / 2); + + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_assign_on_mkdir); + + /* ABMC on, CDP on */ + l3_num_allocated_mbwu = 4; + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, 2); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_assign_on_mkdir); + + /* ABMC 'on', CDP on - but not enough counters */ + l3_num_allocated_mbwu = 1; + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, 0); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_assign_on_mkdir); + + /* Restore global variables that were messed with */ + l3_num_allocated_mbwu = orig_l3_num_allocated_mbwu; + mpam_partid_max = orig_mpam_partid_max; + mpam_pmg_max = orig_mpam_pmg_max; + cdp_enabled = orig_cdp_enabled; +} + 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),
@@ -301,6 +362,7 @@ static struct kunit_case mpam_resctrl_test_cases[] = { KUNIT_CASE(test_percent_to_max_rounding), KUNIT_CASE_PARAM(test_percent_max_roundtrip_stability, test_all_bwa_wd_gen_params), + KUNIT_CASE(test_num_assignable_counters), {} };
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2.43.0