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[Bug 2022877] [NEW] debug in ubuntu_kvm_unit_test timeout with "icebp" related test with J-realtime on openstack AMD64

To: canonical-ubuntu-qa@xxxxxxxxxxxxxxxxxxx
From: Po-Hsu Lin <2022877@xxxxxxxxxxxxxxxxxx>
Date: Mon, 05 Jun 2023 05:17:37 -0000
Reply-to: Bug 2022877 <2022877@xxxxxxxxxxxxxxxxxx>
Sender: noreply@xxxxxxxxxxxxx
Public bug reported:

debug test in ubuntu_kvm_unit_test will timeout with J-realtime on
openstack amd64 instance. This issue can be seen after we start testing
on openstack with 5.15.0-1036.39 in sru-20230320.

Test log:
 Running '/home/ubuntu/autotest/client/tmp/ubuntu_kvm_unit_tests/src/kvm-unit-tests/tests/debug'
 BUILD_HEAD=d8edb59a
 timeout -k 1s --foreground 90s /usr/bin/qemu-system-x86_64 --no-reboot -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=tcg -kernel /tmp/tmp.41OPX1wv8j -smp 1 # -initrd /tmp/tmp.iW4XNY1xjR
 enabling apic
 smp: waiting for 0 APs
 PASS: DR4==DR6 with CR4.DE == 0
 PASS: DR4 read got #UD with CR4.DE == 1
 PASS: #BP
 PASS: hw breakpoint (test that dr6.BS is not set)
 PASS: hw breakpoint (test that dr6.BS is not cleared)
 PASS: Single-step #DB basic test
 PASS: Usermode Single-step #DB basic test
 PASS: Single-step #DB on emulated instructions
 PASS: Usermode Single-step #DB on emulated instructions
 PASS: Single-step #DB w/ STI blocking
 PASS: Usermode Single-step #DB w/ STI blocking
 PASS: Single-step #DB w/ MOVSS blocking
 PASS: Usermode Single-step #DB w/ MOVSS blocking
 qemu-system-x86_64: terminating on signal 15 from pid 9487 (timeout)
 FAIL debug (timeout; duration=90s)

I tried to bump the timeout to 240s but it's not helping, and there is
no output from dmesg when running this test.

It's worthy to note that this test has passed with j/ibm, the whole test sequence should be like this:
 DR4==DR6 with CR4.DE == 0
 DR4 read got #UD with CR4.DE == 1
 #BP
 hw breakpoint (test that dr6.BS is not set)
 hw breakpoint (test that dr6.BS is not cleared)
 Single-step #DB basic test
 Usermode Single-step #DB basic test
 Single-step #DB on emulated instructions
 Usermode Single-step #DB on emulated instructions
 Single-step #DB w/ STI blocking
 Usermode Single-step #DB w/ STI blocking
 Single-step #DB w/ MOVSS blocking
 Usermode Single-step #DB w/ MOVSS blocking
 Single-Step + ICEBP #DB w/ MOVSS blocking
 Usermode Single-Step + ICEBP #DB w/ MOVSS blocking
 Single-step #DB w/ MOVSS blocking and DR7.GD=1
 hw watchpoint (test that dr6.BS is not cleared)
 hw watchpoint (test that dr6.BS is not set)
 icebp 
 MOV SS + watchpoint + ICEBP 
 MOV SS + watchpoint + int $1
 MOV SS + watchpoint + INT3

It's the "icebp" related tests causing this timeout.
If we comment out these 3 tests from kvm-unit-tests/x86/debug.c:
 Usermode Single-Step + ICEBP #DB w/ MOVSS blocking
 icebp 
 MOV SS + watchpoint + ICEBP 

The debug test can finish with one failure:
PASS: DR4==DR6 with CR4.DE == 0
PASS: DR4 read got #UD with CR4.DE == 1
PASS: #BP
PASS: hw breakpoint (test that dr6.BS is not set)
PASS: hw breakpoint (test that dr6.BS is not cleared)
PASS: Single-step #DB basic test
PASS: Usermode Single-step #DB basic test
PASS: Single-step #DB on emulated instructions
PASS: Usermode Single-step #DB on emulated instructions
PASS: Single-step #DB w/ STI blocking
PASS: Usermode Single-step #DB w/ STI blocking
PASS: Single-step #DB w/ MOVSS blocking
PASS: Usermode Single-step #DB w/ MOVSS blocking
FAIL: Single-step #DB w/ MOVSS blocking and DR7.GD=1
PASS: hw watchpoint (test that dr6.BS is not cleared)
PASS: hw watchpoint (test that dr6.BS is not set)
PASS: MOV SS + watchpoint + int $1
PASS: MOV SS + watchpoint + INT3
SUMMARY: 18 tests, 1 unexpected failures
FAIL debug (18 tests, 1 unexpected failures)

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


** Tags: 5.15 amd64 jammy realtime sru-20230320 sru-20230417 sru-20230515

** Summary changed:

- debug in ubuntu_kvm_unit_test timeout with J-realtime on openstack AMD64
+ debug in ubuntu_kvm_unit_test timeout with "icebp" related test with J-realtime on openstack AMD64

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https://bugs.launchpad.net/bugs/2022877

Title:
  debug in ubuntu_kvm_unit_test timeout with "icebp" related test with
  J-realtime on openstack AMD64

Status in ubuntu-kernel-tests:
  New

Bug description:
  debug test in ubuntu_kvm_unit_test will timeout with J-realtime on
  openstack amd64 instance. This issue can be seen after we start
  testing on openstack with 5.15.0-1036.39 in sru-20230320.

  Test log:
   Running '/home/ubuntu/autotest/client/tmp/ubuntu_kvm_unit_tests/src/kvm-unit-tests/tests/debug'
   BUILD_HEAD=d8edb59a
   timeout -k 1s --foreground 90s /usr/bin/qemu-system-x86_64 --no-reboot -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=tcg -kernel /tmp/tmp.41OPX1wv8j -smp 1 # -initrd /tmp/tmp.iW4XNY1xjR
   enabling apic
   smp: waiting for 0 APs
   PASS: DR4==DR6 with CR4.DE == 0
   PASS: DR4 read got #UD with CR4.DE == 1
   PASS: #BP
   PASS: hw breakpoint (test that dr6.BS is not set)
   PASS: hw breakpoint (test that dr6.BS is not cleared)
   PASS: Single-step #DB basic test
   PASS: Usermode Single-step #DB basic test
   PASS: Single-step #DB on emulated instructions
   PASS: Usermode Single-step #DB on emulated instructions
   PASS: Single-step #DB w/ STI blocking
   PASS: Usermode Single-step #DB w/ STI blocking
   PASS: Single-step #DB w/ MOVSS blocking
   PASS: Usermode Single-step #DB w/ MOVSS blocking
   qemu-system-x86_64: terminating on signal 15 from pid 9487 (timeout)
   FAIL debug (timeout; duration=90s)

  I tried to bump the timeout to 240s but it's not helping, and there is
  no output from dmesg when running this test.

  It's worthy to note that this test has passed with j/ibm, the whole test sequence should be like this:
   DR4==DR6 with CR4.DE == 0
   DR4 read got #UD with CR4.DE == 1
   #BP
   hw breakpoint (test that dr6.BS is not set)
   hw breakpoint (test that dr6.BS is not cleared)
   Single-step #DB basic test
   Usermode Single-step #DB basic test
   Single-step #DB on emulated instructions
   Usermode Single-step #DB on emulated instructions
   Single-step #DB w/ STI blocking
   Usermode Single-step #DB w/ STI blocking
   Single-step #DB w/ MOVSS blocking
   Usermode Single-step #DB w/ MOVSS blocking
   Single-Step + ICEBP #DB w/ MOVSS blocking
   Usermode Single-Step + ICEBP #DB w/ MOVSS blocking
   Single-step #DB w/ MOVSS blocking and DR7.GD=1
   hw watchpoint (test that dr6.BS is not cleared)
   hw watchpoint (test that dr6.BS is not set)
   icebp 
   MOV SS + watchpoint + ICEBP 
   MOV SS + watchpoint + int $1
   MOV SS + watchpoint + INT3

  It's the "icebp" related tests causing this timeout.
  If we comment out these 3 tests from kvm-unit-tests/x86/debug.c:
   Usermode Single-Step + ICEBP #DB w/ MOVSS blocking
   icebp 
   MOV SS + watchpoint + ICEBP 

  The debug test can finish with one failure:
  PASS: DR4==DR6 with CR4.DE == 0
  PASS: DR4 read got #UD with CR4.DE == 1
  PASS: #BP
  PASS: hw breakpoint (test that dr6.BS is not set)
  PASS: hw breakpoint (test that dr6.BS is not cleared)
  PASS: Single-step #DB basic test
  PASS: Usermode Single-step #DB basic test
  PASS: Single-step #DB on emulated instructions
  PASS: Usermode Single-step #DB on emulated instructions
  PASS: Single-step #DB w/ STI blocking
  PASS: Usermode Single-step #DB w/ STI blocking
  PASS: Single-step #DB w/ MOVSS blocking
  PASS: Usermode Single-step #DB w/ MOVSS blocking
  FAIL: Single-step #DB w/ MOVSS blocking and DR7.GD=1
  PASS: hw watchpoint (test that dr6.BS is not cleared)
  PASS: hw watchpoint (test that dr6.BS is not set)
  PASS: MOV SS + watchpoint + int $1
  PASS: MOV SS + watchpoint + INT3
  SUMMARY: 18 tests, 1 unexpected failures
  FAIL debug (18 tests, 1 unexpected failures)

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Follow ups

[Bug 2022877] Re: debug in ubuntu_kvm_unit_test timeout with "icebp" related test with J-realtime on openstack AMD64
From: Po-Hsu Lin, 2023-06-05
[Bug 2022877] Re: debug in ubuntu_kvm_unit_test timeout with "icebp" related test with J-realtime on openstack AMD64
From: Po-Hsu Lin, 2023-06-05