Description of problem:

I was hoping to use virt-v2v-in-place to get virtio drivers installed into a windows VM, rather than doing it manually.  I semi-manually imported it from vmware into libvirt using qemu-img and virt-install, because virt-v2v couldn't identify the OS on the disk.  I've done this on about 65 VMs.  Something like 20% had this issue (inspection could not detect the source guest).  I don't know what made that 20% different.

In any case, because I didn't use virt-v2v to do the conversion from vmware, the virtio drivers did not get installed, which is why I'm running virt-v2v-in-place.

The VM is registered with libvirt with a qcow2 image for the disk.  It boots, so things aren't totally screwed up.

If I run virt-v2v-in-place as myself, I get this error:

virt-v2v-in-place vmname
...
mnbdkit: file[1]: error: open: /dev/dm-1: Permission denied

I assume this is expected behavior and I have to run as root.  So I try:

sudo virt-v2v-in-place vmname
...
virt-v2v-in-place: error: libguestfs error: passt exited with status 1

Digging deeper into this using strace, I think this problem is stemming from:

[pid 309845] geteuid()                  = 0
[pid 309845] mkdir("/tmp/libguestfsyIUHch", 0700) = 0
[pid 309845] chmod("/tmp/libguestfsyIUHch", 0755) = 0
[pid 309845] bind(3, {sa_family=AF_UNIX, sun_path="/tmp/libguestfsyIUHch/guestfsd.sock"}, 110) = 0
[pid 309871] execve("/usr/bin/passt.avx2", ["passt", "--one-off", "--socket", "/tmp/libguestfsyIUHch/passt.sock", "--pid", "/tmp/libguestfsyIUHch/passt1.pid", "--address", "redacted", "--netmask", "16", "--mac-addr", "redacted", "--gateway", "redacted"], 0x7ffcb400e7b0 /* 19 vars */) = 0
[pid 309871] geteuid()                  = 0
[pid 309871] openat(AT_FDCWD, "/proc/self/uid_map", O_RDONLY|O_CLOEXEC) = 5
[pid 309871] setuid(65534)              = 0
[pid 309871] connect(7, {sa_family=AF_UNIX, sun_path="/tmp/libguestfsyIUHch/passt.sock"}, 110) = -1 ENOENT (No such file or directory)
[pid 309871] unlink("/tmp/libguestfsyIUHch/passt.sock") = -1 ENOENT (No such file or directory)
[pid 309871] bind(6, {sa_family=AF_UNIX, sun_path="/tmp/libguestfsyIUHch/passt.sock"}, 110) = -1 EACCES (Permission denied)
UNIX domain socket bound at /tmp/libguestfsyIUHch/passt.sock
    kvm ... -device virtio-net-pci,netdev=s -netdev stream,id=s,server=off,addr.type=unix,addr.path=/tmp/libguestfsyIUHch/passt.
[pid 309871] write(2, "\n", 1 <unfinished ...>
[pid 309871] openat(AT_FDCWD, "/tmp/libguestfsyIUHch/passt1.pid", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0600) = -1 EACCES (Permission denied)

Note the setuid call that switches away from root... after creating the temp dir as root.

passt is switching users to someone who does not have permission to write to the temp directory created by the parent process.  My machine does not have a user 65534.

Version-Release number of selected component (if applicable):

$ virt-v2v-in-place --version
virt-v2v-in-place 2.4.0

$ passt --version
passt unknown version

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 24.04 LTS
Release:        24.04
Codename:       noble

Installed using apt-get on ubuntu24.04.  This is pretty much a fresh install.

How reproducible:

100%

I am suspicious this would happen for any libvirt VM on this host based on how early it happens.  Also happens using -i libvirtxml.

Steps to Reproduce:
1. sudo virt-v2v-in-place vmname

Actual results:
virt-v2v-in-place: error: libguestfs error: passt exited with status 1

Expected results:
exit code 0

Additional info:

Using -i disk seems to avoid using passt and triggering the problem.  However, after getting past this passt problem, I hit the same problem virt-v2v originally did:

inspection could not detect the source guest

so looks like I'll be installing the virtio drivers from inside the guest.