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[Bug 2106564] [NEW] powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR discrepancy on certain instance types with B:hwe-5.4

To: canonical-ubuntu-qa@xxxxxxxxxxxxxxxxxxx
From: Koichiro Den <2106564@xxxxxxxxxxxxxxxxxx>
Date: Wed, 09 Apr 2025 03:10:28 -0000
Reply-to: Bug 2106564 <2106564@xxxxxxxxxxxxxxxxxx>
Sender: noreply@xxxxxxxxxxxxx
Public bug reported:

Failure observed on bionic linux-hwe-5.4 5.4.0-214.234~18.04.1
(2025.03.17) on metal P9g-LPAR01kernel.

The failure was consistently observed across three runs (3/3. 100%) on
this machine.

Log output:

    [powerpc/ptrace:ptrace-tm-tar]

      # selftests: powerpc/ptrace: ptrace-tm-tar
      # test: ptrace_tm_tar
      # tags: git_version:unknown
 (X1) # [User Read (Running)]          TAR: 40 PPR: 4000000000000 DSCR: 400
      # [Ptrace Read (Running)]        TAR: 20 PPR: 8000000000000 DSCR: 200
      # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
 (X2) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
      # failure: ptrace_tm_tar
      not ok 1 selftests: powerpc/ptrace: ptrace-tm-tar # exit=1

    [powerpc/ptrace:ptrace-tm-spd-tar]

      # selftests: powerpc/ptrace: ptrace-tm-spd-tar
      # test: ptrace_tm_spd_tar
      # tags: git_version:unknown
 (X3) # [User Read (Running)]          TAR: 40 PPR: 18000000000000 DSCR: 400
      # [Ptrace Read (Running)]        TAR: 30 PPR: c000000000000 DSCR: 300
      # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
 (X4) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
      # failure: ptrace_tm_spd_tar
      not ok 1 selftests: powerpc/ptrace: ptrace-tm-spd-tar # exit=1

* At (X3) above, PPR shoud've been 10000000000000 (Normal) as set at (X4)
  as the transaction is aborted, but it was read as 18000000000000 (High).

  Neither tm_spd_tar() nor trace_tm_spd_tar() (via ptrace) set this value
  (i.e. or 3,3,3) inside or outside the transaction. Given this should be
  an LPAR guest from its naming, its hypervisor side might have done
  something unexpected.

* At (X1) above, PPR should've been 10000000000000 (Normal) as set at (X2),
  but it was read as 4000000000000 (Very low).

  Even though (X1) indicates the possibility that only updated CPPR failed to
  be read by tm_tar()'s mfspr(SPRN_PPR) for some reason (*notice that TAR and
  DSCR values are correctly read by mfspr as shown in the log), it's likely
  that this is just a symptom caused by unexpected behavior from the
  hypervisor, as observed at (X3).

Ref. kernel doc on POWER9 TM issues:
https://www.kernel.org/doc/html/latest/arch/powerpc/transactional_memory.html#power9

P9g-LPAR01kernel is a new test instance type, so this is likely not a regression introduced in this SRU cycle.
This test passed on other environments over many SRU cycles.

** Affects: ubuntu-kernel-tests
     Importance: Undecided
         Status: New


** Tags: 5.4 ppc64el ubuntu-kernel-selftests

** Description changed:

  Failure observed on bionic linux-hwe-5.4 5.4.0-214.234~18.04.1
  (2025.03.17) on metal P9g-LPAR01kernel.
  
  The failure was consistently observed across three runs (3/3. 100%) on
  this machine.
  
  Log output:
  
-     [powerpc/ptrace:ptrace-tm-tar]
+     [powerpc/ptrace:ptrace-tm-tar]
  
-       # selftests: powerpc/ptrace: ptrace-tm-tar
-       # test: ptrace_tm_tar
-       # tags: git_version:unknown
-  (X1) # [User Read (Running)]          TAR: 40 PPR: 4000000000000 DSCR: 400
-       # [Ptrace Read (Running)]        TAR: 20 PPR: 8000000000000 DSCR: 200
-       # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
-  (X2) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
-       # failure: ptrace_tm_tar
-       not ok 1 selftests: powerpc/ptrace: ptrace-tm-tar # exit=1
+       # selftests: powerpc/ptrace: ptrace-tm-tar
+       # test: ptrace_tm_tar
+       # tags: git_version:unknown
+  (X1) # [User Read (Running)]          TAR: 40 PPR: 4000000000000 DSCR: 400
+       # [Ptrace Read (Running)]        TAR: 20 PPR: 8000000000000 DSCR: 200
+       # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
+  (X2) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
+       # failure: ptrace_tm_tar
+       not ok 1 selftests: powerpc/ptrace: ptrace-tm-tar # exit=1
  
-     [powerpc/ptrace:ptrace-tm-spd-tar]
+     [powerpc/ptrace:ptrace-tm-spd-tar]
  
-       # selftests: powerpc/ptrace: ptrace-tm-spd-tar
-       # test: ptrace_tm_spd_tar
-       # tags: git_version:unknown
-  (X3) # [User Read (Running)]          TAR: 40 PPR: 18000000000000 DSCR: 400
-       # [Ptrace Read (Running)]        TAR: 30 PPR: c000000000000 DSCR: 300
-       # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
-  (X4) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
-       # failure: ptrace_tm_spd_tar
-       not ok 1 selftests: powerpc/ptrace: ptrace-tm-spd-tar # exit=1
- 
+       # selftests: powerpc/ptrace: ptrace-tm-spd-tar
+       # test: ptrace_tm_spd_tar
+       # tags: git_version:unknown
+  (X3) # [User Read (Running)]          TAR: 40 PPR: 18000000000000 DSCR: 400
+       # [Ptrace Read (Running)]        TAR: 30 PPR: c000000000000 DSCR: 300
+       # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
+  (X4) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
+       # failure: ptrace_tm_spd_tar
+       not ok 1 selftests: powerpc/ptrace: ptrace-tm-spd-tar # exit=1
  
  * At (X3) above, PPR shoud've been 10000000000000 (Normal) as set at (X4)
-   as the transaction is aborted, but it was read as 18000000000000 (High).
+   as the transaction is aborted, but it was read as 18000000000000 (High).
  
-   Neither tm_spd_tar() nor trace_tm_spd_tar() (via ptrace) never set this value
-   (i.e. or 3,3,3) inside or outside the transaction. Given this should be
-   an LPAR guest from its naming, its hypervisor side might have done to it
-   something unexpected.
+   Neither tm_spd_tar() nor trace_tm_spd_tar() (via ptrace) set this value
+   (i.e. or 3,3,3) inside or outside the transaction. Given this should be
+   an LPAR guest from its naming, its hypervisor side might have done to it
+   something unexpected.
  
  * At (X1) above, PPR should've been 10000000000000 (Normal) as set at (X2),
-   but it was read as 4000000000000 (Very low).
+   but it was read as 4000000000000 (Very low).
  
-   Even though (X1) indicates the possibility that only updated CPPR failed to
-   be read by tm_tar()'s mfspr(SPRN_PPR) for some reason (*notice that TAR and
-   DSCR values are correctly read by mfspr as shown in the log), it's likely
-   that this is just a symptom caused by unexpected behavior from the
-   hypervisor, as observed at (X3).
+   Even though (X1) indicates the possibility that only updated CPPR failed to
+   be read by tm_tar()'s mfspr(SPRN_PPR) for some reason (*notice that TAR and
+   DSCR values are correctly read by mfspr as shown in the log), it's likely
+   that this is just a symptom caused by unexpected behavior from the
+   hypervisor, as observed at (X3).
  
  Ref. kernel doc on POWER9 TM issues:
  https://www.kernel.org/doc/html/latest/arch/powerpc/transactional_memory.html#power9
  
  P9g-LPAR01kernel is a new test instance type, so this is likely not a regression introduced in this SRU cycle.
  This test passed on other environments over many SRU cycles.

** Description changed:

  Failure observed on bionic linux-hwe-5.4 5.4.0-214.234~18.04.1
  (2025.03.17) on metal P9g-LPAR01kernel.
  
  The failure was consistently observed across three runs (3/3. 100%) on
  this machine.
  
  Log output:
  
      [powerpc/ptrace:ptrace-tm-tar]
  
        # selftests: powerpc/ptrace: ptrace-tm-tar
        # test: ptrace_tm_tar
        # tags: git_version:unknown
   (X1) # [User Read (Running)]          TAR: 40 PPR: 4000000000000 DSCR: 400
        # [Ptrace Read (Running)]        TAR: 20 PPR: 8000000000000 DSCR: 200
        # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
   (X2) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
        # failure: ptrace_tm_tar
        not ok 1 selftests: powerpc/ptrace: ptrace-tm-tar # exit=1
  
      [powerpc/ptrace:ptrace-tm-spd-tar]
  
        # selftests: powerpc/ptrace: ptrace-tm-spd-tar
        # test: ptrace_tm_spd_tar
        # tags: git_version:unknown
   (X3) # [User Read (Running)]          TAR: 40 PPR: 18000000000000 DSCR: 400
        # [Ptrace Read (Running)]        TAR: 30 PPR: c000000000000 DSCR: 300
        # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
   (X4) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
        # failure: ptrace_tm_spd_tar
        not ok 1 selftests: powerpc/ptrace: ptrace-tm-spd-tar # exit=1
  
  * At (X3) above, PPR shoud've been 10000000000000 (Normal) as set at (X4)
    as the transaction is aborted, but it was read as 18000000000000 (High).
  
    Neither tm_spd_tar() nor trace_tm_spd_tar() (via ptrace) set this value
    (i.e. or 3,3,3) inside or outside the transaction. Given this should be
-   an LPAR guest from its naming, its hypervisor side might have done to it
+   an LPAR guest from its naming, its hypervisor side might have done
    something unexpected.
  
  * At (X1) above, PPR should've been 10000000000000 (Normal) as set at (X2),
    but it was read as 4000000000000 (Very low).
  
    Even though (X1) indicates the possibility that only updated CPPR failed to
    be read by tm_tar()'s mfspr(SPRN_PPR) for some reason (*notice that TAR and
    DSCR values are correctly read by mfspr as shown in the log), it's likely
    that this is just a symptom caused by unexpected behavior from the
    hypervisor, as observed at (X3).
  
  Ref. kernel doc on POWER9 TM issues:
  https://www.kernel.org/doc/html/latest/arch/powerpc/transactional_memory.html#power9
  
  P9g-LPAR01kernel is a new test instance type, so this is likely not a regression introduced in this SRU cycle.
  This test passed on other environments over many SRU cycles.

-- 
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https://bugs.launchpad.net/bugs/2106564

Title:
  powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR
  discrepancy on certain instance types with B:hwe-5.4

Status in ubuntu-kernel-tests:
  New

Bug description:
  Failure observed on bionic linux-hwe-5.4 5.4.0-214.234~18.04.1
  (2025.03.17) on metal P9g-LPAR01kernel.

  The failure was consistently observed across three runs (3/3. 100%) on
  this machine.

  Log output:

      [powerpc/ptrace:ptrace-tm-tar]

        # selftests: powerpc/ptrace: ptrace-tm-tar
        # test: ptrace_tm_tar
        # tags: git_version:unknown
   (X1) # [User Read (Running)]          TAR: 40 PPR: 4000000000000 DSCR: 400
        # [Ptrace Read (Running)]        TAR: 20 PPR: 8000000000000 DSCR: 200
        # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
   (X2) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
        # failure: ptrace_tm_tar
        not ok 1 selftests: powerpc/ptrace: ptrace-tm-tar # exit=1

      [powerpc/ptrace:ptrace-tm-spd-tar]

        # selftests: powerpc/ptrace: ptrace-tm-spd-tar
        # test: ptrace_tm_spd_tar
        # tags: git_version:unknown
   (X3) # [User Read (Running)]          TAR: 40 PPR: 18000000000000 DSCR: 400
        # [Ptrace Read (Running)]        TAR: 30 PPR: c000000000000 DSCR: 300
        # [Ptrace Read (Checkpointed)]   TAR: 10 PPR: 4000000000000 DSCR: 100
   (X4) # [Ptrace Write (Checkpointed)]  TAR: 40 PPR: 10000000000000 DSCR: 400
        # failure: ptrace_tm_spd_tar
        not ok 1 selftests: powerpc/ptrace: ptrace-tm-spd-tar # exit=1

  * At (X3) above, PPR shoud've been 10000000000000 (Normal) as set at (X4)
    as the transaction is aborted, but it was read as 18000000000000 (High).

    Neither tm_spd_tar() nor trace_tm_spd_tar() (via ptrace) set this value
    (i.e. or 3,3,3) inside or outside the transaction. Given this should be
    an LPAR guest from its naming, its hypervisor side might have done
    something unexpected.

  * At (X1) above, PPR should've been 10000000000000 (Normal) as set at (X2),
    but it was read as 4000000000000 (Very low).

    Even though (X1) indicates the possibility that only updated CPPR failed to
    be read by tm_tar()'s mfspr(SPRN_PPR) for some reason (*notice that TAR and
    DSCR values are correctly read by mfspr as shown in the log), it's likely
    that this is just a symptom caused by unexpected behavior from the
    hypervisor, as observed at (X3).

  Ref. kernel doc on POWER9 TM issues:
  https://www.kernel.org/doc/html/latest/arch/powerpc/transactional_memory.html#power9

  P9g-LPAR01kernel is a new test instance type, so this is likely not a regression introduced in this SRU cycle.
  This test passed on other environments over many SRU cycles.

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Follow ups

[Bug 2106564] Re: powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR discrepancy on Power9 PowerVM with j/linux
From: Manuel Diewald, 2025-04-16
[Bug 2106564] Re: powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR discrepancy on Power9 PowerVM with j/linux
From: Koichiro Den, 2025-04-15
[Bug 2106564] Re: powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR discrepancy on Power9 PowerVM with j/linux
From: Po-Hsu Lin, 2025-04-15
[Bug 2106564] Re: powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR discrepancy on certain instance types with B:hwe-5.4
From: Po-Hsu Lin, 2025-04-15
[Bug 2106564] Re: powerpc/ptrace:{ptrace-tm-tar, ptrace-tm-spd-tar} fail with PPR discrepancy on certain instance types with B:hwe-5.4
From: Koichiro Den, 2025-04-09