Remote desktop on Gnome hangs randomly

ovicz

Setting pci=nomsi seems to do the trick for now. Probably not optimal but it's just a VM and I didn't notice any performance issues.

olivierlambert

Adding @Team-OS-Platform-Release in case that rings a bell

yann

Since GPU passthrough is involved I'd ping @Team-Hypervisor-Kernel

ovicz

If i remove the pci=nomsi from grub..this pops up in xl dmesg.

(XEN) [15627.724045] CPU3: Running in modulated clock mode
(XEN) [15628.457337] d[IDLE]v0: Unsupported MSI delivery mode 7 for Dom5
(XEN) [15628.457339] d[IDLE]v2: Unsupported MSI delivery mode 7 for Dom5

That's when the gnome desktop hangs. Is this fixable ?

dinhngtu

@ovicz Are you up for a test package with a fix? Note that the fix is not yet tested nor supported at the moment.

Add user repos using this command:

yum-config-manager --add-repo https://koji.xcp-ng.org/repos/user/8/8.3/xcpng-users.repo

To know what you need to upgrade, run this command (as xcp-ng-ndinh2 contains some changes that you don't need):

rpm -qa --qf '%{NAME}\t%{SOURCERPM}\n' | grep $'\txapi'

Then upgrade just the XAPI-related packages:

yum update --enablerepo=xcp-ng-ndinh2 <list of packages from above>

Remember to reboot the host after installing.

Finally, disable hvm-pirq on your affected VM and reboot it (parameter name subject to change):

xe vm-param-set uuid=... platform:hvm-pirq=false

To go back, list what you installed and downgrade them:

yum list installed | grep ndinh
yum downgrade ...

ovicz

Hello. I did what you said and it seems to work. Thank you.

dinhngtu

@ovicz Thanks for testing. Is everything working without the pci=nomsi or GRUB command line tweaks? We'll work to integrate this fix into a future update.

ovicz

Yes. I removed pci=nomsi entry from grub. I've tested on a Debian Forky and CentOS Stream 10 VMs with gnome and an intel alderlake igpu passthrough no issues at all.

dinhngtu

@ovicz xapi-26.1.16-1.1.0.pirq.2.xcpng8.3 is now available on xcp-ng-ndinh2, which disables HVM PIRQ for all existing VMs by default on reboot. Please try it out.

I've prepared an upstream PR for this feature. If you'd like to be listed as a tester, please respond with your name and email address (or your fake github email if you prefer) and I'll update my commit with your credit.

ovicz

@dinhngtu Hello. There is no need to give me credit. I just want to help so others and myself included can benefit from this. Anyway thank you for your work.