This is a note to let you know that I've just added the patch titled perf/x86/intel/uncore: Reduce the number of CBOX counters to the 5.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: perf-x86-intel-uncore-reduce-the-number-of-cbox-coun.patch and it can be found in the queue-5.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit ccd1fbb8a99365ef1ff85a4333acd3f35c091a4c Author: Kan Liang <kan.liang@xxxxxxxxxxxxxxx> Date: Fri Sep 25 06:49:05 2020 -0700 perf/x86/intel/uncore: Reduce the number of CBOX counters [ Upstream commit ee139385432e919f4d1f59b80edbc073cdae1391 ] 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@xxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200925134905.8839-3-kan.liang@xxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c index e2c683fe42645..4aa735694e030 100644 --- 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,