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arm_mpam: Disable preemption when making accesses to fake MSC in kunit test

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Accesses to MSC must be made from a cpu that is affine to that MSC and the
driver checks this in __mpam_write_reg() using smp_processor_id(). A fake
in-memory MSC is used for testing. When using that, it doesn't matter which
cpu we access it from but calling smp_processor_id() from a preemptible
context gives warnings when running with CONFIG_DEBUG_PREEMPT.

Add a test helper that wraps mpam_reset_msc_bitmap() with preemption
disabled to ensure all (fake) MSC accesses are made with preemption
disabled.

Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ben Horgan
2026-03-06 18:27:17 +00:00
committed by Will Deacon
parent 4ad79c874e
commit c1376f1ff3
1 changed files with 13 additions and 5 deletions
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18
drivers/resctrl/test_mpam_devices.c
View File

@@ -322,6 +322,14 @@ static void test_mpam_enable_merge_features(struct kunit *test)
mutex_unlock(&mpam_list_lock);
}
static void __test_mpam_reset_msc_bitmap(struct mpam_msc *msc, u16 reg, u16 wd)
{
/* Avoid warnings when running with CONFIG_DEBUG_PREEMPT */
guard(preempt)();
mpam_reset_msc_bitmap(msc, reg, wd);
}
static void test_mpam_reset_msc_bitmap(struct kunit *test)
{
char __iomem *buf = kunit_kzalloc(test, SZ_16K, GFP_KERNEL);
@@ -341,31 +349,31 @@ static void test_mpam_reset_msc_bitmap(struct kunit *test)
test_result = (u32 *)(buf + MPAMCFG_CPBM);
mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 0);
__test_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);
__test_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);
__test_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);
__test_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);
__test_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;