Can you find and attach the XML for the VM?  For "permanent" VM's that'd be /etc/libvirt/qemu/{VM}.xml... You may find something at /var/run/libvirt/qemu/{VM}.* too. 

Makes it easier to reproduce since devs may not use cockpit normally.

Perhaps some more details from /var/log/libvirt/qemu/{VM}.log?  Getting a process dump/trace of why qemu-kvm failed will help too.

I'm a bit rusty on the common debugging/logging needs for libvirt to get qemu data.

Sorry for late. Here enabled debug log for libvritd. See if it help or guide me to collect the right logs. Many thanks.
https://drive.google.com/file/d/1frTLK6CA3I2fu_3AU2zzy8mSDeOTL9iu/view?usp=sharing

Hello Kai,

I test with rhel9 but I couldn't reproduce the issue, could you help to check my steps?

Version:
cockpit-259-1.el9.x86_64
qemu-kvm-6.2.0-1.el9.x86_64
libvirt-7.10.0-1.el9.x86_64
kernel-5.14.0-39.el9.x86_64


Steps:
1. Login to cockpit
2. Create a virtual network with the default options
Now there are a Storage pool and a Network available.
3. Create a VM also with default options but remove "Immediately start VM"
Installation type tried local install media and URL.
4. New VM is created, click "install" to start the installation

Results:
I created 4 VMs successfully.

Dear Zixi,
Yes, i follow your step and can create VM.
Seem like issue only happen if Install type choose "Download an OS". See if you got same result. Many thanks.
Best Regards,
KAI

Thanks, KAI. I can reproduce this issue. There are two issues, one is SELinux preventing /usr/bin/ps from sys_ptrace access on the cap_userns labeled ksmtuned_t, the other is after disabling Selinux, still fail to create VM. 

Steps:
1. login to cockpit
2. create a VM with Install type choose "Download an OS" and remove the "Immediately start VM" default option, the other options just use the default value.

Results:
Cockpit reports VM creation failed, check 'journalctl' log, it shows:
setroubleshoot[8961]: SELinux is preventing /usr/bin/ps from sys_ptrace access on the cap_userns labeled ksmtuned_t. For complete SELinux messages>
setroubleshoot[8961]: SELinux is preventing /usr/bin/ps from sys_ptrace access on the cap_userns labeled ksmtuned_t.
                                                                              
                                                                              *****  Plugin catchall (100. confidence) suggests   **************************
                                                                              
                                                                              If you believe that ps should be allowed sys_ptrace access on cap_userns labeled ksmtuned_t by default.
                                                                              Then you should report this as a bug.
                                                                              You can generate a local policy module to allow this access.
                                                                              Do
                                                                              allow this access for now by executing:
                                                                              # ausearch -c 'ps' --raw | audit2allow -M my-ps
                                                                              # semodule -X 300 -i my-ps.pp
There is a fixed Fedora bug reported the same issue, but no bug for rhel8/9. 

If disable SELinux, the VM creation still failed, no log found under /var/log/libvirt/qemu/ directory, nor any log in journalctl, but I can see the image is created in /var/lib/libvirt/images/test.qcow2.

HI KAI, It seems is the same with this issue https://bugzilla.redhat.com/show_bug.cgi?id=2032462. Could you please check whether there is an error like follow in web console(F12 -> Console)
"Traceback (most recent call last):
  File "<stdin>", line 356, in <module>
  File "<stdin>", line 273, in create_vm
  File "<stdin>", line 310, in inject_metadata
  File "/usr/lib64/python3.9/xml/etree/ElementTree.py", line 1347, in XML
    parser.feed(text)
xml.etree.ElementTree.ParseError: junk after document element: line 61, column 0"

Also, could you please add the version of cockpit-machines? Thanks

Dear Yunming,

Yes, same error in browser console.

Traceback (most recent call last):
  File "<stdin>", line 356, in <module>
  File "<stdin>", line 273, in create_vm
  File "<stdin>", line 310, in inject_metadata
  File "/usr/lib64/python3.9/xml/etree/ElementTree.py", line 1347, in XML
    parser.feed(text)
xml.etree.ElementTree.ParseError: junk after document element: line 61, column 0
cockpit.js:1:8157
spawn 'vm creation' returned error: "{"problem":null,"exit_status":1,"exit_signal":null,"message":"Traceback (most recent call last):\n  File \"<stdin>\", line 356, in <module>\n  File \"<stdin>\", line 273, in create_vm\n  File \"<stdin>\", line 310, in inject_metadata\n  File \"/usr/lib64/python3.9/xml/etree/ElementTree.py\", line 1347, in XML\n    parser.feed(text)\nxml.etree.ElementTree.ParseError: junk after document element: line 61, column 0"}"

version:
cockpit-machines-258.1-1.el9.noarch

Best Regards,
KAI

Thanks, Yunming and Kai, close this bug as a duplicate of https://bugzilla.redhat.com/show_bug.cgi?id=2032462.

*** This bug has been marked as a duplicate of bug 2032462 ***