[Bug 1872401] Re: vmx_nm_test in ubuntu_kvm_unit_tests interrupted on X-oracle-4.15 / B-oracle-4.15 / X-KVM / B-KVM

This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
bionic' to 'verification-done-bionic'. If the problem still exists,
change the tag 'verification-needed-bionic' to 'verification-failed-
bionic'.

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: verification-needed-bionic

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https://bugs.launchpad.net/bugs/1872401

Title:
vmx_nm_test in ubuntu_kvm_unit_tests interrupted on X-oracle-4.15 /
B-oracle-4.15 / X-KVM / B-KVM

Status in ubuntu-kernel-tests:
New
Status in linux package in Ubuntu:
Invalid
Status in linux source package in Bionic:
Fix Committed

Bug description:
[Impact]
When running kvm-unit-tests under a guest, it will be paused, requiring a
reset. When running the same test on a host (vmx_nm_test), it will fail.

[Test case]
Grab kvm-unit-tests, build it and run:

TESTNAME=vmx TIMEOUT=90s ACCEL= ./x86/run x86/vmx.flat -smp 1 -cpu
host,+vmx -append "vmx_nm_test"

If done inside a guest, when the host runs the bionic 4.15 kernel, the guest
will pause.

[Potential regressions]
Nested KVM could stop working. Floating point could stop working on KVM
guests, though the code that relied on this was already removed from
Bionic.


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


This issue was first spotted on Mar.16 [1]

The ubuntu_kvm_unit_tests will be interrupted on X-oracle-4.15 on both
VM.Standard2.1 and VM.Standard2.16, this is not a regression since it
can be reproduced with 4.15.0-1031-oracle #34~16.04.1:

Running '/home/ubuntu/autotest/client/tmp/ubuntu_kvm_unit_tests/src/kvm-unit-tests/tests/vmx_nm_test'
 BUILD_HEAD=4671e4ba
 timeout -k 1s --foreground 30 /usr/bin/qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel /tmp/tmp.da3iFrsCzC -smp 1 -cpu host,+vmx -append vmx_nm_test # -initrd /tmp/tmp.h2DFw8L0AF
 enabling apic
 paging enabled
 cr0 = 80010011
 cr3 = 477000
 cr4 = 20

 Test suite: vmx_nm_test
client_loop: send disconnect: Broken pipe
(node disconnected here)

Before the test started, this can be found in syslog:
Apr 13 06:26:25 selfprovisioned-phlin-kvm-unit kernel: [ 1073.529005] L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.

After that, noting was printed and node disconnected.

If you try to run this case manually, it will stop at:
# ./vmx_nm_test
BUILD_HEAD=4671e4ba
ready!!!
timeout -k 1s --foreground 30 /usr/bin/qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel /tmp/tmp.ZcGrnXu6se -smp 1 -cpu host,+vmx -append vmx_nm_test # -initrd /tmp/tmp.ADjEOAcRKM
enabling ap
(stopped here, even the "enabling apic" string was not printed)

It looks like this is a new test case added since the cycle of
4.15.0-1037.41~16.04.1-oracle

[1] https://bugs.launchpad.net/ubuntu-kernel-
tests/+bug/1867623/comments/2

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.15.0-1031-oracle 4.15.0-1031.34~16.04.1
ProcVersionSignature: User Name 4.15.0-1031.34~16.04.1-oracle 4.15.18
Uname: Linux 4.15.0-1031-oracle x86_64
ApportVersion: 2.20.1-0ubuntu2.21
Architecture: amd64
Date: Mon Apr 13 05:18:03 2020
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: linux-signed-oracle
UpgradeStatus: No upgrade log present (probably fresh install)

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