* [PATCH] arm_mpam: On saving mbwu state read the monitors before clearing CFG_MBWU_CTL
@ 2026-10-03 13:12 Ben Horgan
2026-10-06 22:56 ` Catalin Marinas
0 siblings, 1 reply; 2+ messages in thread
From: Ben Horgan @ 2026-10-03 13:12 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, ben.horgan
Cc: catalin.marinas, will, james.morse, reinette.chatre, fenghuay
In mpam_save_mbwu_state() the monitor values are read using __ris_msmon_read_locked()
which checks if the configuration provided matches that in the hardware and if
not then resets the monitor. To avoid resetting the monitor before reading the
value that needs saving only clear the configuration after the monitor is read.
Fixes: d056d29aefbe ("arm_mpam: Use __ris_msmon_read() for saving MBWU state")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
based on arm64 for-next/mpam
---
drivers/resctrl/mpam_devices.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index c32175426433..48adc49b833c 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -2052,9 +2052,6 @@ static int mpam_save_mbwu_state(void *arg)
if (ret)
return ret;
ret = mpam_read_monsel_reg(msc, CFG_MBWU_CTL, &cur_ctl);
- if (ret)
- return ret;
- ret = mpam_write_monsel_reg(msc, CFG_MBWU_CTL, 0);
if (ret)
return ret;
@@ -2088,6 +2085,10 @@ static int mpam_save_mbwu_state(void *arg)
mbwu_state->correction = val;
}
+ ret = mpam_write_monsel_reg(msc, CFG_MBWU_CTL, 0);
+ if (ret)
+ return ret;
+
mpam_mon_sel_unlock(msc);
}
--
2.43.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] arm_mpam: On saving mbwu state read the monitors before clearing CFG_MBWU_CTL
2026-10-03 13:12 [PATCH] arm_mpam: On saving mbwu state read the monitors before clearing CFG_MBWU_CTL Ben Horgan
@ 2026-10-06 22:56 ` Catalin Marinas
0 siblings, 0 replies; 2+ messages in thread
From: Catalin Marinas @ 2026-10-06 22:56 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, Ben Horgan
Cc: Will Deacon, james.morse, reinette.chatre, fenghuay
On Sat, 03 Oct 2026 14:12:07 +0100, Ben Horgan wrote:
> In mpam_save_mbwu_state() the monitor values are read using __ris_msmon_read_locked()
> which checks if the configuration provided matches that in the hardware and if
> not then resets the monitor. To avoid resetting the monitor before reading the
> value that needs saving only clear the configuration after the monitor is read.
Applied to arm64 (for-next/mpam), thanks!
[1/1] arm_mpam: On saving mbwu state read the monitors before clearing CFG_MBWU_CTL
https://git.kernel.org/arm64/c/197a7a41e6e0
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