diff options
| author | Like Xu | 2020-06-13 16:09:49 +0800 |
|---|---|---|
| committer | Peter Zijlstra | 2020-07-02 15:51:46 +0200 |
| commit | 097e4311cda952dfb047f2a49d35aa5de500d474 (patch) | |
| tree | 9dc6dff0a1c21956573c584478be689113e72e0c /arch/x86/events/intel | |
| parent | b2d6504761a50b9493eb4b20f6e188b673f20c32 (diff) | |
perf/x86: Add constraint to create guest LBR event without hw counter
The hypervisor may request the perf subsystem to schedule a time window
to directly access the LBR records msrs for its own use. Normally, it would
create a guest LBR event with callstack mode enabled, which is scheduled
along with other ordinary LBR events on the host but in an exclusive way.
To avoid wasting a counter for the guest LBR event, the perf tracks its
hw->idx via INTEL_PMC_IDX_FIXED_VLBR and assigns it with a fake VLBR
counter with the help of new vlbr_constraint. As with the BTS event,
there is actually no hardware counter assigned for the guest LBR event.
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200514083054.62538-5-like.xu@linux.intel.com
Diffstat (limited to 'arch/x86/events/intel')
| -rw-r--r-- | arch/x86/events/intel/core.c | 18 | ||||
| -rw-r--r-- | arch/x86/events/intel/lbr.c | 4 |
2 files changed, 22 insertions, 0 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 8dac4c61bf76..51e1fba7b1d1 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2621,6 +2621,20 @@ intel_bts_constraints(struct perf_event *event) return NULL; } +/* + * Note: matches a fake event, like Fixed2. + */ +static struct event_constraint * +intel_vlbr_constraints(struct perf_event *event) +{ + struct event_constraint *c = &vlbr_constraint; + + if (unlikely(constraint_match(c, event->hw.config))) + return c; + + return NULL; +} + static int intel_alt_er(int idx, u64 config) { int alt_idx = idx; @@ -2811,6 +2825,10 @@ __intel_get_event_constraints(struct cpu_hw_events *cpuc, int idx, { struct event_constraint *c; + c = intel_vlbr_constraints(event); + if (c) + return c; + c = intel_bts_constraints(event); if (c) return c; diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index 2ed3f2a51bdf..d285d26c1578 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -1363,3 +1363,7 @@ int x86_perf_get_lbr(struct x86_pmu_lbr *lbr) return 0; } EXPORT_SYMBOL_GPL(x86_perf_get_lbr); + +struct event_constraint vlbr_constraint = + FIXED_EVENT_CONSTRAINT(INTEL_FIXED_VLBR_EVENT, + (INTEL_PMC_IDX_FIXED_VLBR - INTEL_PMC_IDX_FIXED)); |