** Changed in: linux-aws (Ubuntu Jammy)
Status: In Progress => Fix Committed
** Changed in: linux-aws (Ubuntu Kinetic)
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1968062
Title:
Jammy / Kinetic: Enable Hibernation for Xen Based Instance Types
Status in linux-aws package in Ubuntu:
Fix Committed
Status in linux-aws source package in Jammy:
Fix Committed
Status in linux-aws source package in Kinetic:
Fix Committed
Bug description:
[Impact]
Hibernation currently fails for all AWS Xen instance types
(c3/c4/i3/m3/m4/r3/r4/t2) with all Jammy 5.15 and Kinetic 5.19 linux-
aws kernels.
When attempting to hibernate, the system gets stuck in
sync_inodes_one_sb() when processing the rootfs, fails to hibernate,
and shuts down. When you start the instance, it starts fresh, and does
not resume from the incomplete hibernation image. Networking is also
broken, and you cannot ssh in.
Upon review of the jammy/linux-aws git log, it appears that the kernel
is missing AWS hibernation enablement patches entirely. These need to
be included to get hibernation working.
[Fix]
Hibernation currently works on the Amazon Linux 2 5.15 Kernel:
https://github.com/amazonlinux/linux/tree/amazon-5.15.y/mainline
After careful review of the amazon-5.15.y/mainline branch, we have
found the below set of patches authored by Amazon AWS Hibernation team
to be minimally sufficient to get hibernation working on both Jammy
5.15 and Kinetic 5.19.
xen: Restore xen-pirqs on resume from hibernation
xen-netfront: call netif_device_attach on resume
xen: Only restore the ACPI SCI interrupt in xen_restore_pirqs.
xen: restore pirqs on resume from hibernation.
block: xen-blkfront: consider new dom0 features on restore
x86: tsc: avoid system instability in hibernation
xen-blkfront: Fixed blkfront_restore to remove a call to negotiate_mq
Revert "xen: dont fiddle with event channel masking in suspend/resume"
PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA
x86/xen: close event channels for PIRQs in system core suspend callback
xen/events: add xen_shutdown_pirqs helper function
x86/xen: save and restore steal clock
xen/time: introduce xen_{save,restore}_steal_clock
xen-netfront: add callbacks for PM suspend and hibernation support
xen-blkfront: add callbacks for PM suspend and hibernation
x86/xen: add system core suspend and resume callbacks
x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume
xenbus: add freeze/thaw/restore callbacks support
xen/manage: introduce helper function to know the on-going suspend mode
xen/manage: keep track of the on-going suspend mode
These patches will be carried as SAUCE patches, and their subjects
marked with "UBUNTU: SAUCE [aws]". Their upstream is the Amazon
Hibernation team, with the repo being the Amazon Linux 2 kernel repo.
[Testcase]
1. Log into Amazon EC2.
2. Select Launch Instance.
3. Under Instance Type, select any from (c3/c4/i3/m3/m4/r3/r4/t2). I suggest
t2.medium.
4. Select the "Ubuntu 22.04 LTS HVM (SSD type)" AMI in the quicklaunch pane.
5. Select your SSH keypair.
6. In storage, select 20gb. Go to the advanced tab, and set Encrypted: Yes.
7. Under Advanced Settings for the instance, set "Stop - Hibernate" to Enable.
8. Create the Instance. SSH in.
9. Wait 5 minutes for hibinit-agent to create /swap-hibinit swapfile and
configure grub.
10. Start a screen session. Echo some text and then detach with ctrl-d.
11. Log out from instance.
12. In EC2, select "Instance State" > "Hibernate".
13. Wait 30 seconds to one minute. The state will go from "Stopping" to
"Stopped".
14. Start the instance again.
15. SSH in.
16. Attempt to resume screen session with "screen -r".
If you are not able to ssh into the instance, hibernation had failed.
If ssh works and the screen session is still running, hibernation was
successful.
Alternatively, the CPC team can run their Hibernation testsuite over
Jammy and Kinetic.
We have built test kernels for Jammy and Kinetic with the patches, and
they are available in the below ppa:
https://launchpad.net/~gerald-yang-tw/+archive/ubuntu/aws-hibernate-
test
If you try and hibernate and resume with the test kernels, hibernation
is successful.
[Where problems could occur]
We are adding a significant amount of code to the Xen subsystem,
spread across many commits. This code has not been mainlined, and is
instead maintained out of tree by the Amazon AWS Hibernation team.
The changes target hibernation, block devices, and clock devices,
specific to those used on AWS Xen instances. Most of these patches
have been applied to Xenial, Bionic, Focal and other series for a long
time, but some patches are new for 5.15 onward.
The changes will only target linux-aws to try and limit regression
risk to AWS users, and any regressions will be limited to users of Xen
based instance types (c3/c4/i3/m3/m4/r3/r4/t2), covering both Xen 4.2
and Xen 4.11.
If a regression were to occur, the instance would likely fail to
hibernate, and at worst, write an incomplete hibernation image to the
swapfile. The kernel will see this on start, and instead of resuming
from the hibernation image, will start fresh. It is unlikely to cause
any filesystem corruption on the rootfs, but any in progress
computations at the time of hibernation could be lost. The current
broken behaviour breaks networking, and users would have to power
cycle the instance a few times before they can ssh in again.
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