XCP-ng 8.2 updates announcements and testing

Digitalllama

@stormi could you provide some more details about the "transient live migration error" with the xenopsd update?

I have been experiencing issues live migrating larger VM's (20-40GB Ram) especially when the memory is in active use (eg MariaDB database). As far as I can tell my issue is related to the VM dynamic memory being reduced to below the actual memory use of the VM at which point a random processes crash - but not sure why this is happening since both the source and target XCP host are under allocated on memory. We upgraded all hosts in the pool before xenopsd was withdrawn and are currently scheduling in downtime for each VM so we can migrate them in an off state which seems to bypass the issue.

stormi

@Digitalllama The issue you had is probably not related to that update. If that was caused by the update, then you'd have seen the VM reboot at the end of the migration process and it would have been duplicated on both hosts.

A dynamic memory minimum value set too low can cause the kind of process crash you experienced: the available memory for the VM being low, you may reach a point where the VM's kernel needs to fire the Out Of Memory Killer which will select a running process and kill it. If you want to be sure about that, you can try to set the same value for minimum and maximum dynamic memory and see if the migration issue still occurs.

stormi

To people not having updated their hosts yet with the latest update: wait a few more days! There's a kernel security update on its way, so you'll probably want to reboot only then.

Note that the security update will be mostly useful for people who put their hosts on a network that is reachable from a potential attacker.

stormi

The new kernel update candidate is available. As usual, I need some feedback before I can push it to everyone.

Citrix advisory: https://support.citrix.com/article/CTX256725

XCP-ng 7.5: install it with yum update kernel --enablerepo='xcp-ng-updates_testing'
XCP-ng 7.6: install it with yum update kernel --enablerepo='xcp-ng-updates_testing'
XCP-ng 8.0 beta/RC1: simply yum update

It is a security update. A distant attacker could manage to crash your host or raise its memory usage significantly with specially crafted network requests. Hosts isolated from public networks are safe, unless the attacker managed to get into your private network.

Reboot required (we do not support live patching at the moment, due to a closed source component in XenServer / Citrix Hypervisor).

Edit: update pushed: https://xcp-ng.org/blog/2019/07/12/xcp-ng-security-bulletin-kernel-update-sack-vulnerability/

stormi

Anyone available to test the security update on 7.5 and/or 7.6? It is a security update, so quite urgent.

cnaumer

Installed it a view minutes ago. Will report back.

cnaumer

Updated 3 hosts and so far no Problems. Transferred some machines etc no bad effects.

stormi

Hello everyone. I'm back from holidays with update candidates that need testing!

XCP-ng 7.6

xcp-ng-xapi-plugins

yum update xcp-ng-xapi-plugins --enablerepo=xcp-ng-updates_testing

This is the most important update. It fixes host memory consumption issues that could go as far as crashing several hosts at the same time (especially if EPEL repositories were active, which shouldn't be the case but often was prior to XCP-ng 8.0 where they are already present but disabled by default). Already fixed in XCP-ng 8.0.

Post-install: xe-toolstack-restart

microcode_ctl

yum update microcode_ctl --enablerepo=xcp-ng-updates_testing

Microcode update for the SandyBridge family of CPUs regarding the MDS attacks.

Post-install: reboot if you want it to be taken into account.

xcp-ng-pv-tools

yum update xcp-ng-pv-tools --enablerepo=xcp-ng-updates_testing

Linux guest tools: support for SLES 15 SP1, updated README, support for recent CoreOS.

Post-install: nothing to do.

xen

yum update xen-dom0-libs xen-dom0-tools xen-hypervisor xen-libs xen-tools --enablerepo=xcp-ng-updates_testing

Avoids possible memory corruption when forcibly shutting down a VM with AMD MxGPU attached. Or when the guest crashes.

Post-install: reboot to apply the changes.

XCP-ng 8.0

xen + guest templates

yum update xen-dom0-libs xen-dom0-tools xen-hypervisor xen-libs xen-tools guest-templates-json guest-templates-json-data-windows guest-templates-json-data-xenapp guest-templates-json-data-linux guest-templates-json-data-other --enablerepo=xcp-ng-testing

Avoid doing that on several hosts of the same pool at the same time, because the guest-template-json* updates will need to update the XAPI database at the same time. The /usr/bin/create-guest-templates tool that is called post-update is not designed to run concurrently (thanks to Silmaril on IRC for finding out at the cost of a broken XAPI database).

Changes:

same fix as in XCP-ng 7.6 regarding VMs with AMD MxGPU attached
fix a host crash that can occur when you force-shutdown a Windows VM that is in an unclean state
Windows VMs could hang for more than a minute after live migration
Windows VMs with the viridian_reference_tsc flag enabled could crash during live migration. This fix opens the door to possible performance improvements for your Windows VMs, because following that fix now Citrix advises to set viridian_reference_tsc and viridian_stimer flags to true for better performance.
Updated Windows VM templates with new default settings that set viridian_* to true.

Post-install:

reboot the host to apply the xen changes
consider modifying your existing Windows VM settings for possible better performance. See "After installing this hotfix" in https://support.citrix.com/article/CTX258320

microcode_ctl

yum update microcode_ctl --enablerepo=xcp-ng-testing

Microcode update for the SandyBridge family of CPUs regarding the MDS attacks. XCP-ng 8.0 already contained updated microcodes from Intel when released, before Citrix released a hotfix, but their update contains one additional file so we synced with their package.

Post-install: reboot if you want it to be taken into account.

What we need

As usual, Vates tests the updates internally, but we also rely on the community to widen the test cases and hardware tested, so we need you to install the updates and give us feedback, either positive or negative, before we can consider pushing those updates to everyone!

MajorTom

@stormi said in Updates announcements and testing:

XCP-ng 7.6

[...]

microcode_ctl
yum update microcode_ctl --enablerepo=xcp-ng-updates_testing
Microcode update for the SandyBridge family of CPUs regarding the MDS attacks.

Post-install: reboot if you want it to be taken into account.

xcp-ng-pv-tools
yum update microcode_ctl --enablerepo=xcp-ng-updates_testing

I guess that above command for xcp-ng-pv-tools should not be the same as the one for microcode_ctl

XCP-ng 8.0

[...]

microcode_ctl

yum update microcode_ctl --enablerepo=xcp-ng-updates_testing

This command returns error:

# yum update microcode_ctl --enablerepo=xcp-ng-updates_testing
Loaded plugins: fastestmirror


Error getting repository data for xcp-ng-updates_testing, repository not found

I guess it meant to be:

# yum update microcode_ctl --enablerepo=xcp-ng-testing

as this worked for me.

HTH

MajorTom

I installed all these updates for 8.0 and rebooted the host.

The reboot was extraordinary long. The time from shutting ssh session to getting ping packets back again was about 8 minutes. I don't know what it was doing during all this time as I rebooted remotely.

So I rebooted once more to see whether the boot time would be so long again.
This time it was only 1 minutes 46 seconds.

The VMs seem to run OK so far, but it's just a test host with two VMs doing almost nothing, so I don't know for sure :-).

stormi

@MajorTom thanks, I've fixed the post

cnaumer

@stormi Installed the updates in our test pool. Until now everything is working. VM migration etc. Also set viridian flags as advised ( xoa vm has this set also? is this OK?)
Regards

Christian

olivierlambert

I think Viridian will only have an effect on Windows VMs.

stormi

Thanks to those who tested. Still interested in feedback, including on XCP-ng 7.6.

stormi

I'll need at least one tester for the latest update candidates on XCP-ng 7.6, and one for 8.0.

cnaumer

OK. Installed it on our last 7.6 server. Reboot was OK. VMs run fine. As this is a test host I cannot test more. It runs on AMD so the microcode_ctl should do nothing on our server.

stormi

@cnaumer Thanks, this is good enough for me at this stage of the testing, so I can push the 7.6 updates now thanks to you!

cnaumer

@cnaumer said in Updates announcements and testing:

@stormi Installed the updates in our test pool. Until now everything is working. VM migration etc. Also set viridian flags as advised ( xoa vm has this set also? is this OK?)
Regards

Christian

This was an 8.0 pool here. Just to clarify this.

MajorTom

@stormi said in Updates announcements and testing:

I'll need at least one tester for the latest update candidates on XCP-ng 7.6, and one for 8.0.

At 8.0:
I did yum update, but there are only new versions of guest-templates-json*, so can't quite see anything to check.

Just in case I rebooted the host. The reboot took about 1 minute 40 seconds which i s OK for this host.

The test VMs started OK as well.

olivierlambert

That's enough to check if everything is fine