canonical-ubuntu-qa team mailing list archive

[Manuel Diewald <2052632@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

log_check/kernel_tainted tests will fail on AmpereOne based machines
like c3a-standard-4 for focal:linux 5.4.0-168.186 and newer. The kernel
will issue the following warning and consequently taint the kernel:

[    0.022227] WARNING: CPU: 1 PID: 17 at arch/arm64/kernel/cpu_errata.c:1387 spectre_bhb_enable_mitigation+0x130/0x250
[    0.022229] Modules linked in:
[    0.022232] CPU: 1 PID: 17 Comm: migration/1 Not tainted 5.4.0-172-generic #190-Ubuntu
[    0.022234] pstate: 20400085 (nzCv daIf +PAN -UAO)
[    0.022236] pc : spectre_bhb_enable_mitigation+0x130/0x250
[    0.022237] lr : spectre_bhb_enable_mitigation+0x104/0x250
[    0.022238] sp : ffff8000100fbcf0
[    0.022239] x29: ffff8000100fbcf0 x28: 0000000000000002 
[    0.022241] x27: ffff80001003bd10 x26: 0000000000000000 
[    0.022242] x25: 0000000000000060 x24: 0000000000000000 
[    0.022243] x23: 0000000000000001 x22: ffffd491a3079380 
[    0.022244] x21: ffffd491a2395890 x20: ffffd491a32a4518 
[    0.022246] x19: ffffd491a32a4508 x18: 0000000000000030 
[    0.022247] x17: 000000007474b4b6 x16: 0000000092b3f138 
[    0.022248] x15: ffff4ba4fa21eff0 x14: ffffffffffffffff 
[    0.022249] x13: 0000000000000040 x12: 0000000000000001 
[    0.022250] x11: ffffd491a225efa0 x10: 0000000000000b00 
[    0.022252] x9 : ffff8000100fbd30 x8 : ffff4ba4fa26f620 
[    0.022253] x7 : 0000000000000000 x6 : ffffd491a1e33008 
[    0.022254] x5 : 00000000ff0ffff0 x4 : 0000000000f0000f 
[    0.022255] x3 : 00000000c00fac30 x2 : 000000000000000b 
[    0.022256] x1 : ffffd491a32a4508 x0 : 000000000000000b 
[    0.022258] Call trace:
[    0.022259]  spectre_bhb_enable_mitigation+0x130/0x250
[    0.022261]  cpu_enable_non_boot_scope_capabilities+0x6c/0xa8
[    0.022264]  multi_cpu_stop+0xac/0x188
[    0.022265]  cpu_stopper_thread+0xec/0x190
[    0.022267]  smpboot_thread_fn+0x150/0x1d0
[    0.022269]  kthread+0xf0/0x118
[    0.022271]  ret_from_fork+0x10/0x18

The warning was introduced with upstream commit

f41cab7a4653 arm64: Add AMPERE1 to the Spectre-BHB affected list

that came with upstream stable release v5.4.253 as part of
Ubuntu-5.4.0-168.186:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2038652

Looking at the code, this warning will always be issued on AMPERE1 based
machines but Spectre-BHB mitigation should be guaranteed regardless.

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

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https://bugs.launchpad.net/bugs/2052632

Title:
  f/linux: log_check WARNING on c3a-standard-4

Status in ubuntu-kernel-tests:
  New

Bug description:
  log_check/kernel_tainted tests will fail on AmpereOne based machines
  like c3a-standard-4 for focal:linux 5.4.0-168.186 and newer. The
  kernel will issue the following warning and consequently taint the
  kernel:

  [    0.022227] WARNING: CPU: 1 PID: 17 at arch/arm64/kernel/cpu_errata.c:1387 spectre_bhb_enable_mitigation+0x130/0x250
  [    0.022229] Modules linked in:
  [    0.022232] CPU: 1 PID: 17 Comm: migration/1 Not tainted 5.4.0-172-generic #190-Ubuntu
  [    0.022234] pstate: 20400085 (nzCv daIf +PAN -UAO)
  [    0.022236] pc : spectre_bhb_enable_mitigation+0x130/0x250
  [    0.022237] lr : spectre_bhb_enable_mitigation+0x104/0x250
  [    0.022238] sp : ffff8000100fbcf0
  [    0.022239] x29: ffff8000100fbcf0 x28: 0000000000000002 
  [    0.022241] x27: ffff80001003bd10 x26: 0000000000000000 
  [    0.022242] x25: 0000000000000060 x24: 0000000000000000 
  [    0.022243] x23: 0000000000000001 x22: ffffd491a3079380 
  [    0.022244] x21: ffffd491a2395890 x20: ffffd491a32a4518 
  [    0.022246] x19: ffffd491a32a4508 x18: 0000000000000030 
  [    0.022247] x17: 000000007474b4b6 x16: 0000000092b3f138 
  [    0.022248] x15: ffff4ba4fa21eff0 x14: ffffffffffffffff 
  [    0.022249] x13: 0000000000000040 x12: 0000000000000001 
  [    0.022250] x11: ffffd491a225efa0 x10: 0000000000000b00 
  [    0.022252] x9 : ffff8000100fbd30 x8 : ffff4ba4fa26f620 
  [    0.022253] x7 : 0000000000000000 x6 : ffffd491a1e33008 
  [    0.022254] x5 : 00000000ff0ffff0 x4 : 0000000000f0000f 
  [    0.022255] x3 : 00000000c00fac30 x2 : 000000000000000b 
  [    0.022256] x1 : ffffd491a32a4508 x0 : 000000000000000b 
  [    0.022258] Call trace:
  [    0.022259]  spectre_bhb_enable_mitigation+0x130/0x250
  [    0.022261]  cpu_enable_non_boot_scope_capabilities+0x6c/0xa8
  [    0.022264]  multi_cpu_stop+0xac/0x188
  [    0.022265]  cpu_stopper_thread+0xec/0x190
  [    0.022267]  smpboot_thread_fn+0x150/0x1d0
  [    0.022269]  kthread+0xf0/0x118
  [    0.022271]  ret_from_fork+0x10/0x18

  The warning was introduced with upstream commit

  f41cab7a4653 arm64: Add AMPERE1 to the Spectre-BHB affected list

  that came with upstream stable release v5.4.253 as part of
  Ubuntu-5.4.0-168.186:
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2038652

  Looking at the code, this warning will always be issued on AMPERE1
  based machines but Spectre-BHB mitigation should be guaranteed
  regardless.

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