get_ibs_op_count() adds hardware's current count (IbsOpCurCnt) bits to its count regardless of hardware's valid status.
According to the PPR for AMD Family 17h Model 31h B0 55803 Rev 0.54, if the counter rolls over, valid status is set, and the lower 7 bits of IbsOpCurCnt are randomized by hardware. Don't include those bits in the driver's event count. Signed-off-by: Kim Phillips <[email protected]> Fixes: 8b1e13638d46 ("perf/x86-ibs: Fix usage of IBS op current count") Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 Cc: Stephane Eranian <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Michael Petlan <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: LKML <[email protected]> Cc: x86 <[email protected]> Cc: [email protected] --- v2: no changes. arch/x86/events/amd/ibs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c index 3eb9a55e998c..68776cc291a6 100644 --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -334,11 +334,15 @@ static u64 get_ibs_op_count(u64 config) { u64 count = 0; + /* + * If the internal 27-bit counter rolled over, the count is MaxCnt + * and the lower 7 bits of CurCnt are randomized. + * Otherwise CurCnt has the full 27-bit current counter value. + */ if (config & IBS_OP_VAL) - count += (config & IBS_OP_MAX_CNT) << 4; /* cnt rolled over */ - - if (ibs_caps & IBS_CAPS_RDWROPCNT) - count += (config & IBS_OP_CUR_CNT) >> 32; + count = (config & IBS_OP_MAX_CNT) << 4; + else if (ibs_caps & IBS_CAPS_RDWROPCNT) + count = (config & IBS_OP_CUR_CNT) >> 32; return count; } -- 2.27.0
