Arm KVM guests fail to start if KVM_CREATE_VM returns EINTR

[dann frazier]

[Impact]
KVM-accelerated virtual machines sometimes fail to start on ARM.

[Test Case]
My reproducer is to run 6 parallel VM create/destroy loop - using the attached test.sh script. When this issue is hit, a VM will fail with the following in its log:

2023-05-16T21:07:37.300791Z qemu-system-aarch64: Failed to retrieve host
CPU features
2023-05-16 21:07:37.466+0000: shutting down, reason=failed

[Fix]
https://gitlab.com/qemu-project/qemu/-/commit/bbde13cd14ad4eec18529ce0bf5876058464e124

[What Could Go Wrong]
There may exist conditions that could cause the added loop to block for a long time, burning CPU. However, the fix uses a seemingly common pattern.

[Christian Ehrhardt  (paelzer)]

The fix is in qemu 7.2, so >=Lunar is already fixed.
But this really looks like a straight forward case to SRU.

[Andreas Hasenack (ahasenack)]

Hello dann, or anyone else affected,

Accepted qemu into kinetic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/qemu/1:7.0+dfsg-7ubuntu2.4 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-kinetic to verification-done-kinetic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-kinetic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Andreas Hasenack (ahasenack)]

Hello dann, or anyone else affected,

Accepted qemu into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/qemu/1:6.2+dfsg-2ubuntu6.9 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[dann frazier (dannf)]

= verification =
I started my test loop on both a kinetic and a jammy system *without* these updates installed, and verified that they are hitting this condition frequently as a baseline (notably, they hit it 64 and 32 times respectively). I then upgraded to the -proposed versions, and let them continue to run for at least 30 minutes and verified that neither hit this condition after the update.

Tested versions:

6.2+dfsg-2ubuntu6.9
7.0+dfsg-7ubuntu2.4

EDIT: The loop continued to run successfully overnight

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted qemu (1:7.0+dfsg-7ubuntu2.4) for kinetic have finished running.
The following regressions have been reported in tests triggered by the package:

ganeti/3.0.2-1ubuntu1 (armhf)
sbuild/0.83.1ubuntu1 (amd64, arm64, ppc64el, s390x)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/kinetic/update_excuses.html#qemu

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted qemu (1:6.2+dfsg-2ubuntu6.9) for jammy have finished running.
The following regressions have been reported in tests triggered by the package:

livecd-rootfs/2.765.20 (amd64)
sbuild/0.81.2ubuntu6 (amd64, arm64, ppc64el, s390x)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/jammy/update_excuses.html#qemu

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package qemu - 1:7.0+dfsg-7ubuntu2.4

---------------
qemu (1:7.0+dfsg-7ubuntu2.4) kinetic; urgency=medium

  * d/p/u/lp-2019766-target-arm-kvm-Retry-KVM_CREATE_VM-call-if-it-fails-.patch:
    ARM: Retry KVM_CREATE_VM when it returns EINTR (LP: #2019766)

 -- dann frazier <email address hidden> Tue, 16 May 2023 14:59:50 -0600

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for qemu has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package qemu - 1:6.2+dfsg-2ubuntu6.9

---------------
qemu (1:6.2+dfsg-2ubuntu6.9) jammy; urgency=medium

  * d/p/u/lp-2019766-target-arm-kvm-Retry-KVM_CREATE_VM-call-if-it-fails-.patch:
    ARM: Retry KVM_CREATE_VM when it returns EINTR (LP: #2019766)

 -- dann frazier <email address hidden> Tue, 16 May 2023 14:59:54 -0600