[Bug 218739] pmu_counters_test kvm-selftest fails with (count != NUM_INSNS_RETIRED)

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=218739

Dongli Zhang (dongli.zhang@oracle.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dongli.zhang@oracle.com

--- Comment #1 from Dongli Zhang (dongli.zhang@oracle.com) ---
Perhaps more information can be printed by pmu_counters_test in the future,
e.g., msr, msr_ctrl, their values, cflush and whether forced emulation?

Just from the output, the number of instructions by GUEST_MEASURE_EVENT() does
not match with NUM_INSNS_RETIRED=17,

------------------------

I have tried on an Icelake server and I could not reproduce anything for most
of times, except the below for only once.

# ./pmu_counters_test 
Testing arch events, PMU version 0, perf_caps = 0
Testing GP counters, PMU version 0, perf_caps = 0
Testing fixed counters, PMU version 0, perf_caps = 0
Testing arch events, PMU version 0, perf_caps = 2000
Testing GP counters, PMU version 0, perf_caps = 2000
Testing fixed counters, PMU version 0, perf_caps = 2000
Testing arch events, PMU version 1, perf_caps = 0
Testing GP counters, PMU version 1, perf_caps = 0
Testing fixed counters, PMU version 1, perf_caps = 0
Testing arch events, PMU version 1, perf_caps = 2000
Testing GP counters, PMU version 1, perf_caps = 2000
Testing fixed counters, PMU version 1, perf_caps = 2000
Testing arch events, PMU version 2, perf_caps = 0
Testing GP counters, PMU version 2, perf_caps = 0
Testing fixed counters, PMU version 2, perf_caps = 0
Testing arch events, PMU version 2, perf_caps = 2000
Testing GP counters, PMU version 2, perf_caps = 2000
Testing fixed counters, PMU version 2, perf_caps = 2000
Testing arch events, PMU version 3, perf_caps = 0
Testing GP counters, PMU version 3, perf_caps = 0
Testing fixed counters, PMU version 3, perf_caps = 0
Testing arch events, PMU version 3, perf_caps = 2000
Testing GP counters, PMU version 3, perf_caps = 2000
Testing fixed counters, PMU version 3, perf_caps = 2000
Testing arch events, PMU version 4, perf_caps = 0
==== Test Assertion Failure ====
  x86_64/pmu_counters_test.c:120: count != 0
  pid=39696 tid=39696 errno=4 - Interrupted system call
     1  0x0000000000402baf: run_vcpu at pmu_counters_test.c:61
     2  0x0000000000402ddd: test_arch_events at pmu_counters_test.c:307
     3  0x0000000000402683: test_arch_events at pmu_counters_test.c:605
     4   (inlined by) test_intel_counters at pmu_counters_test.c:605
     5   (inlined by) main at pmu_counters_test.c:635
     6  0x00007fcfeb43ae44: ?? ??:0
     7  0x000000000040288d: _start at ??:?
  0x0 == 0x0 (count == 0)


# cat /sys/module/kvm/parameters/enable_pmu 
Y
# cat /sys/module/kvm/parameters/force_emulation_prefix 
0

# cpuid -l 0xa -1
CPU:
   Architecture Performance Monitoring Features (0xa):
      version ID                               = 0x5 (5)
      number of counters per logical processor = 0x8 (8)
      bit width of counter                     = 0x30 (48)
      length of EBX bit vector                 = 0x8 (8)
      core cycle event                         = available
      instruction retired event                = available
      reference cycles event                   = available
      last-level cache ref event               = available
      last-level cache miss event              = available
      branch inst retired event                = available
      branch mispred retired event             = available
      top-down slots event                     = available
      fixed counter  0 supported               = true
      fixed counter  1 supported               = true
      fixed counter  2 supported               = true
      fixed counter  3 supported               = true
      fixed counter  4 supported               = false
      fixed counter  5 supported               = false
      fixed counter  6 supported               = false
      fixed counter  7 supported               = false
      fixed counter  8 supported               = false
      fixed counter  9 supported               = false
      fixed counter 10 supported               = false
      fixed counter 11 supported               = false
      fixed counter 12 supported               = false
      fixed counter 13 supported               = false
      fixed counter 14 supported               = false
      fixed counter 15 supported               = false
      fixed counter 16 supported               = false
      fixed counter 17 supported               = false
      fixed counter 18 supported               = false
      fixed counter 19 supported               = false
      fixed counter 20 supported               = false
      fixed counter 21 supported               = false
      fixed counter 22 supported               = false
      fixed counter 23 supported               = false
      fixed counter 24 supported               = false
      fixed counter 25 supported               = false
      fixed counter 26 supported               = false
      fixed counter 27 supported               = false
      fixed counter 28 supported               = false
      fixed counter 29 supported               = false
      fixed counter 30 supported               = false
      fixed counter 31 supported               = false
      number of contiguous fixed counters      = 0x4 (4)
      bit width of fixed counters              = 0x30 (48)
      anythread deprecation                    = true



-------------------------------------------

I also did tests on nested L1 hypervisor (more legacy hardware). Most of time
are good, except once.

# ./pmu_counters_test
Testing arch events, PMU version 0, perf_caps = 0
Testing GP counters, PMU version 0, perf_caps = 0
Testing fixed counters, PMU version 0, perf_caps = 0
Testing arch events, PMU version 0, perf_caps = 2000
Testing GP counters, PMU version 0, perf_caps = 2000
Testing fixed counters, PMU version 0, perf_caps = 2000
Testing arch events, PMU version 1, perf_caps = 0
Testing GP counters, PMU version 1, perf_caps = 0
Testing fixed counters, PMU version 1, perf_caps = 0
Testing arch events, PMU version 1, perf_caps = 2000
Testing GP counters, PMU version 1, perf_caps = 2000
Testing fixed counters, PMU version 1, perf_caps = 2000
Testing arch events, PMU version 2, perf_caps = 0
Testing GP counters, PMU version 2, perf_caps = 0
Testing fixed counters, PMU version 2, perf_caps = 0
Testing arch events, PMU version 2, perf_caps = 2000
Testing GP counters, PMU version 2, perf_caps = 2000
Testing fixed counters, PMU version 2, perf_caps = 2000
Testing arch events, PMU version 3, perf_caps = 0
==== Test Assertion Failure ====
  x86_64/pmu_counters_test.c:120: count != 0
  pid=9301 tid=9301 errno=4 - Interrupted system call
     1  0x0000000000402bdf: run_vcpu at pmu_counters_test.c:61
     2  0x0000000000402dfd: test_arch_events at pmu_counters_test.c:307
     3  0x00000000004026a3: test_arch_events at pmu_counters_test.c:605
     4   (inlined by) test_intel_counters at pmu_counters_test.c:605
     5   (inlined by) main at pmu_counters_test.c:635
     6  0x00007f05e2f60d8f: ?? ??:0
     7  0x00007f05e2f60e3f: ?? ??:0
     8  0x00000000004028b4: _start at ??:?
  0x0 == 0x0 (count == 0)

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