From: Ravi Bangoria ravi.bangoria@amd.com
[ Upstream commit 46dcf85566170d4528b842bf83ffc350d71771fa ]
IBS Op uses two counters: MaxCnt and CurCnt. MaxCnt is programmed with the desired sample period. IBS hw generates sample when CurCnt reaches to MaxCnt. The size of these counter used to be 20 bits but later they were extended to 27 bits. The 7 bit extension is indicated by CPUID Fn8000_001B_EAX[6 / OpCntExt].
perf_ibs->cnt_mask variable contains bit masks for MaxCnt and CurCnt. But IBS driver does not set upper 7 bits of CurCnt in cnt_mask even when OpCntExt CPUID bit is set. Fix this.
IBS driver uses cnt_mask[CurCnt] bits only while disabling an event. Fortunately, CurCnt bits are not read from MSR while re-enabling the event, instead MaxCnt is programmed with desired period and CurCnt is set to 0. Hence, we did not see any issues so far.
Signed-off-by: Ravi Bangoria ravi.bangoria@amd.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Namhyung Kim namhyung@kernel.org Link: https://lkml.kernel.org/r/20250115054438.1021-5-ravi.bangoria@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/events/amd/ibs.c | 3 ++- arch/x86/include/asm/perf_event.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c index c3a2f6f57770a..8f3b5764e139d 100644 --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -1222,7 +1222,8 @@ static __init int perf_ibs_op_init(void) if (ibs_caps & IBS_CAPS_OPCNTEXT) { perf_ibs_op.max_period |= IBS_OP_MAX_CNT_EXT_MASK; perf_ibs_op.config_mask |= IBS_OP_MAX_CNT_EXT_MASK; - perf_ibs_op.cnt_mask |= IBS_OP_MAX_CNT_EXT_MASK; + perf_ibs_op.cnt_mask |= (IBS_OP_MAX_CNT_EXT_MASK | + IBS_OP_CUR_CNT_EXT_MASK); }
if (ibs_caps & IBS_CAPS_ZEN4) diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h index 7505bb5d260ab..aa351c4a20eee 100644 --- a/arch/x86/include/asm/perf_event.h +++ b/arch/x86/include/asm/perf_event.h @@ -520,6 +520,7 @@ struct pebs_xmm { */ #define IBS_OP_CUR_CNT (0xFFF80ULL<<32) #define IBS_OP_CUR_CNT_RAND (0x0007FULL<<32) +#define IBS_OP_CUR_CNT_EXT_MASK (0x7FULL<<52) #define IBS_OP_CNT_CTL (1ULL<<19) #define IBS_OP_VAL (1ULL<<18) #define IBS_OP_ENABLE (1ULL<<17)