[PATCH 1/3] arm_mpam: Fix monitor instance selection when checking for hardware NRDY

From: Ben Horgan

Date: Thu May 07 2026 - 11:28:45 EST


In _mpam_ris_hw_probe_hw_nrdy() a new register value to select the first
monitor and relevant RIS is prepared in mon_sel. However, it is written to
the monitor value register, e.g. MSMON_CSU, rather than MSMON_CFG_MON_SEL.

As MSMON_CFG_MON_SEL is a 32 bit register update the type of mon_sel to
u32. Write mon_sel to the intended register, MSMON_CFG_MON_SEL.

Fixes: 8c90dc68a5de ("arm_mpam: Probe the hardware features resctrl supports")
Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
---
drivers/resctrl/mpam_devices.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 41b14344b16f..817cb10a8e79 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -731,7 +731,7 @@ static void mpam_enable_quirks(struct mpam_msc *msc)
static bool _mpam_ris_hw_probe_hw_nrdy(struct mpam_msc_ris *ris, u32 mon_reg)
{
u32 now;
- u64 mon_sel;
+ u32 mon_sel;
bool can_set, can_clear;
struct mpam_msc *msc = ris->vmsc->msc;

@@ -740,7 +740,7 @@ static bool _mpam_ris_hw_probe_hw_nrdy(struct mpam_msc_ris *ris, u32 mon_reg)

mon_sel = FIELD_PREP(MSMON_CFG_MON_SEL_MON_SEL, 0) |
FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx);
- _mpam_write_monsel_reg(msc, mon_reg, mon_sel);
+ mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);

_mpam_write_monsel_reg(msc, mon_reg, MSMON___NRDY);
now = _mpam_read_monsel_reg(msc, mon_reg);
--
2.43.0