perf/x86/intel/uncore: Reduce the number of CBOX counters

An oops is triggered by the fuzzy test.

[  327.853081] unchecked MSR access error: RDMSR from 0x70c at rIP:
0xffffffffc082c820 (uncore_msr_read_counter+0x10/0x50 [intel_uncore])
[  327.853083] Call Trace:
[  327.853085]  <IRQ>
[  327.853089]  uncore_pmu_event_start+0x85/0x170 [intel_uncore]
[  327.853093]  uncore_pmu_event_add+0x1a4/0x410 [intel_uncore]
[  327.853097]  ? event_sched_in.isra.118+0xca/0x240

There are 2 GP counters for each CBOX, but the current code claims 4
counters. Accessing the invalid registers triggers the oops.

Fixes: 6e394376ee89 ("perf/x86/intel/uncore: Add Intel Icelake uncore support")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200925134905.8839-3-kan.liang@linux.intel.com

diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c
index 2bdfcf8..de3d962 100644 (file)
--- a/arch/x86/events/intel/uncore_snb.c
+++ b/arch/x86/events/intel/uncore_snb.c
@@ -325,7 +325,7 @@ static struct intel_uncore_ops icl_uncore_msr_ops = {
 
 static struct intel_uncore_type icl_uncore_cbox = {
        .name           = "cbox",
-       .num_counters   = 4,
+       .num_counters   = 2,
        .perf_ctr_bits  = 44,
        .perf_ctr       = ICL_UNC_CBO_0_PER_CTR0,
        .event_ctl      = SNB_UNC_CBO_0_PERFEVTSEL0,