Comment 21 for bug 1968131

Install fine:

ubuntu@swtpm-jammy:/var/lib/swtpm$ sudo apt update; sudo apt upgrade
Hit:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Hit:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease
Hit:3 http://security.ubuntu.com/ubuntu jammy-security InRelease
Hit:4 http://archive.ubuntu.com/ubuntu jammy-backports InRelease
Get:5 https://ppa.launchpadcontent.net/paelzer/lp-1968131-swtpm-rndfile/ubuntu jammy InRelease [18.1 kB]
Get:6 https://ppa.launchpadcontent.net/paelzer/lp-1968131-swtpm-rndfile/ubuntu jammy/main amd64 Packages [768 B]
Get:7 https://ppa.launchpadcontent.net/paelzer/lp-1968131-swtpm-rndfile/ubuntu jammy/main Translation-en [472 B]
Fetched 19.3 kB in 2s (10.4 kB/s)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
2 packages can be upgraded. Run 'apt list --upgradable' to see them.
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  swtpm swtpm-tools
2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 138 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 https://ppa.launchpadcontent.net/paelzer/lp-1968131-swtpm-rndfile/ubuntu jammy/main amd64 swtpm-tools amd64 0.6.3-0ubuntu2~jammyppa1 [90.4 kB]
Get:2 https://ppa.launchpadcontent.net/paelzer/lp-1968131-swtpm-rndfile/ubuntu jammy/main amd64 swtpm amd64 0.6.3-0ubuntu2~jammyppa1 [47.4 kB]
Fetched 138 kB in 2s (85.7 kB/s)
(Reading database ... 113960 files and directories currently installed.)
Preparing to unpack .../swtpm-tools_0.6.3-0ubuntu2~jammyppa1_amd64.deb ...
Unpacking swtpm-tools (0.6.3-0ubuntu2~jammyppa1) over (0.6.3-0ubuntu1) ...
Preparing to unpack .../swtpm_0.6.3-0ubuntu2~jammyppa1_amd64.deb ...
Unpacking swtpm (0.6.3-0ubuntu2~jammyppa1) over (0.6.3-0ubuntu1) ...
Setting up swtpm (0.6.3-0ubuntu2~jammyppa1) ...
Setting up swtpm-tools (0.6.3-0ubuntu2~jammyppa1) ...
Processing triggers for man-db (2.10.2-1) ...
Processing triggers for libc-bin (2.35-0ubuntu3) ...
Scanning processes...
Scanning linux images...

Running kernel seems to be up-to-date.

No services need to be restarted.

No containers need to be restarted.

No user sessions are running outdated binaries.

No VM guests are running outdated hypervisor (qemu) binaries on this host.

Now it works:
ubuntu@swtpm-jammy:/var/lib/swtpm$ virsh start testguest
Domain 'testguest' started

P.S. it also made me find that the modified swtpm triggers a non fatal apparmor issue now that we want to fix in another bug

Apr 07 15:02:26 swtpm-jammy kernel: audit: type=1400 audit(1649343746.681:87): apparmor="DENIED" operation="open" profile="libvirt-202a34a9-2ee2-4826-b206-c249f535be90" name="/etc/ssl/openssl.cnf" pid=15149 comm="swtpm" requested_mask="r" denied_mask="r" fsuid=113 ouid=0