[PATCH 1/2] arm_mpam: Force __iomem casts

Krzysztof Kozlowski krzysztof.kozlowski at oss.qualcomm.com
Mon Feb 16 03:02:41 PST 2026


Code allocates standard kernel memory to pass to the MPAM, which expects
__iomem.  The code is safe, because __iomem accessors should work fine
on kernel mapped memory, however leads to sparse warnings:

  test_mpam_devices.c:327:42: warning: incorrect type in initializer (different address spaces)
  test_mpam_devices.c:327:42:    expected char [noderef] __iomem *buf
  test_mpam_devices.c:327:42:    got void *
  test_mpam_devices.c:342:24: warning: cast removes address space '__iomem' of expression

Cast the pointer to memory via __force to silence them.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>
---
 drivers/resctrl/test_mpam_devices.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/resctrl/test_mpam_devices.c b/drivers/resctrl/test_mpam_devices.c
index 3e8d564a0c64..2de41b47c138 100644
--- a/drivers/resctrl/test_mpam_devices.c
+++ b/drivers/resctrl/test_mpam_devices.c
@@ -324,7 +324,7 @@ static void test_mpam_enable_merge_features(struct kunit *test)
 
 static void test_mpam_reset_msc_bitmap(struct kunit *test)
 {
-	char __iomem *buf = kunit_kzalloc(test, SZ_16K, GFP_KERNEL);
+	char __iomem *buf = (__force char __iomem *)kunit_kzalloc(test, SZ_16K, GFP_KERNEL);
 	struct mpam_msc fake_msc = {};
 	u32 *test_result;
 
@@ -339,7 +339,7 @@ static void test_mpam_reset_msc_bitmap(struct kunit *test)
 	mutex_init(&fake_msc.part_sel_lock);
 	mutex_lock(&fake_msc.part_sel_lock);
 
-	test_result = (u32 *)(buf + MPAMCFG_CPBM);
+	test_result = (__force u32 *)(buf + MPAMCFG_CPBM);
 
 	mpam_reset_msc_bitmap(&fake_msc, MPAMCFG_CPBM, 0);
 	KUNIT_EXPECT_EQ(test, test_result[0], 0);
-- 
2.51.0




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