Re: [perf] unchecked MSR access error: WRMSR to 0x689 in intel_pmu_lbr_restore

[Vince Weaver]

On Wed, 6 Jul 2022, Vince Weaver wrote:

> Let the fuzzer running a long time on 5.19-rc1 and after a few weeks it 
> triggered this weird trace.  It is repeatable (although I haven't 
> narrowed down exactly what's causing it).
> 
> It's odd in that it just dumps a <TASK>, it doesn't provide any info on 
> what the actual trigger is.
> 
> This is on a Haswell machine.

I bumped up to current git and managed to trigger this again, this time 
it actually managed to print the error message.

[ 7763.384369] unchecked MSR access error: WRMSR to 0x689 (tried to write 0x1fffffff8101349e) at rIP: 0xffffffff810704a4 (native_write_msr+0x4/0x20)
[ 7763.397420] Call Trace:
[ 7763.399881]  <TASK>
[ 7763.401994]  intel_pmu_lbr_restore+0x9a/0x1f0
[ 7763.406363]  intel_pmu_lbr_sched_task+0x91/0x1c0
[ 7763.410992]  __perf_event_task_sched_in+0x1cd/0x240
[ 7763.415879]  ? __perf_event_task_sched_out+0x75/0x5c0
[ 7763.420939]  finish_task_switch.isra.0+0x15b/0x2a0
[ 7763.425740]  ? __switch_to+0x112/0x430
[ 7763.429503]  __schedule+0x2cf/0x10d0
[ 7763.433088]  ? send_signal_locked+0xc8/0x130
[ 7763.437364]  schedule+0x4e/0xb0
[ 7763.440518]  do_wait+0x15b/0x2f0
[ 7763.443757]  kernel_wait4+0xa6/0x140
[ 7763.447337]  ? thread_group_exited+0x60/0x60
[ 7763.451608]  do_syscall_64+0x3b/0xc0
[ 7763.455199]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[ 7763.460259] RIP: 0033:0x7f9063feba26
[ 7763.463838] Code: ff e9 0e 00 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 11 b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 90 48 83 ec 28 89 54 24 14 48 89 74 24
[ 7763.482587] RSP: 002b:00007ffca3875c08 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
[ 7763.490161] RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007f9063feba26
[ 7763.497303] RDX: 0000000000000000 RSI: 00007ffca3875c1c RDI: 0000000000002214
[ 7763.504441] RBP: 00007ffca3875c20 R08: 00007f90640f321c R09: 00007f90640f3240
[ 7763.511577] R10: 0000000000000000 R11: 0000000000000246 R12: 000055d6ce93c4f0
[ 7763.518718] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 7763.525850]  </TASK>