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Commit dc48eb1ff27c excluded the 63-bit > MSMON_MBWU_LWD format while scaling the shorter counters. Systems > selecting the preferred 63-bit counter consequently report bandwidth > values that are 64 times too small. > > Apply the scale to both the sampled value and overflow correction for > the 63-bit format. Unsigned arithmetic retains modulo-u64 behavior > when the scaled counter range exceeds u64. > > Fixes: dc48eb1ff27c ("arm_mpam: Add workaround for T241-MPAM-6") > Link: https://lore.kernel.org/lkml/20240816131432.993859-1-sdonthineni@nvidia.com/ > Signed-off-by: Shanker Donthineni Cc: Reviewed-by: Fenghua Yu Tested-by: Fenghua Yu Reported-by: Garima Kochhar This is a hardware quirk fix and should be in stable. Thanks. -Fenghua > --- > drivers/resctrl/mpam_devices.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index 2f09f4b78bd3b..b68f5599e8dbe 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -1196,8 +1196,7 @@ static u64 mpam_msmon_overflow_val(enum mpam_device_features type, > { > u64 overflow_val = __mpam_msmon_overflow_val(type); > > - if (mpam_has_quirk(T241_MBW_COUNTER_SCALE_64, msc) && > - type != mpam_feat_msmon_mbwu_63counter) > + if (mpam_has_quirk(T241_MBW_COUNTER_SCALE_64, msc)) > overflow_val *= 64; > > return overflow_val; > @@ -1293,8 +1292,7 @@ static void __ris_msmon_read(void *arg) > now = FIELD_GET(MSMON___VALUE, now); > } > > - if (mpam_has_quirk(T241_MBW_COUNTER_SCALE_64, msc) && > - m->type != mpam_feat_msmon_mbwu_63counter) > + if (mpam_has_quirk(T241_MBW_COUNTER_SCALE_64, msc)) > now *= 64; > > if (nrdy)