Re: [KVM] 21d4c575eb: perf-sanity-tests.Test_event_parsing.fail

[Sean Christopherson]

On Sun, Oct 09, 2022, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed the following commit (built with gcc-11):
> 
> commit: 21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba ("KVM: x86: Print error code in exception injection tracepoint iff valid")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> in testcase: perf-sanity-tests
> version: 
> with following parameters:
> 
> 	perf_compiler: gcc
> 
> on test machine: 4 threads Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz (Skylake) with 32G memory
> 
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):

What exactly is changing?  I see some "FAILED!" entries, but I don't see how a
commit that only affects tracepoint string output can be related to things like
"Lookup mmap thread".  If the issue is that the output change caused
"Parse event definition strings" to fail, and that propagated to everything else,
then this is effectively "working as intended".

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index d07428e660e3..385436d12024 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -376,10 +376,11 @@ TRACE_EVENT(kvm_inj_exception,
                __entry->reinjected     = reinjected;
        ),
 
-       TP_printk("%s (0x%x)%s",
+       TP_printk("%s%s%s%s%s",
                  __print_symbolic(__entry->exception, kvm_trace_sym_exc),
-                 /* FIXME: don't print error_code if not present */
-                 __entry->has_error ? __entry->error_code : 0,
+                 !__entry->has_error ? "" : " (",
+                 !__entry->has_error ? "" : __print_symbolic(__entry->error_code, { }),
+                 !__entry->has_error ? "" : ")",
                  __entry->reinjected ? " [reinjected]" : "")
 );

> 2022-10-08 04:47:24 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 6
>   6: Parse event definition strings                                  :
>   6.1: Test event parsing                                            : FAILED!

> 2022-10-08 04:48:12 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 19
>  19: 'import perf' in python                                         : FAILED!

> 2022-10-08 04:48:36 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 31
>  31: Lookup mmap thread                                              : FAILED!

> 2022-10-08 04:48:45 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 72
>  72: dlfilter C API                                                  : FAILED!

> 2022-10-08 04:48:46 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 75
>  75: Test dwarf unwind                                               : FAILED!

> 2022-10-08 04:48:47 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 80
>  80: build id cache operations                                       : FAILED!

> 2022-10-08 04:49:27 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 89
>  89: perf stat CSV output linter                                     : FAILED!

> 2022-10-08 04:49:51 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 94
>  94: perf all metrics test                                           : FAILED!

> 2022-10-08 04:56:05 sudo /usr/src/perf_selftests-x86_64-rhel-8.3-func-21d4c575eb4a1e6d956b61b5e9c162895fa7d4ba/tools/perf/perf test 101
> 101: Miscellaneous Intel PT testing                                  : FAILED!