Comment 22 for bug 1789551

Tested prior to update:
PID 4732
Seccomp: 2
Seccomp: 0

Update:
$ sudo apt install qemu-block-extra qemu-kvm qemu-system-common qemu-system-x86 qemu-utils
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following package was automatically installed and is no longer required:
  grub-pc-bin
Use 'sudo apt autoremove' to remove it.
Suggested packages:
  samba vde2 ovmf
The following packages will be upgraded:
  qemu-block-extra qemu-kvm qemu-system-common qemu-system-x86 qemu-utils
5 upgraded, 0 newly installed, 0 to remove and 68 not upgraded.
Need to get 6782 kB of archives.
After this operation, 8192 B of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 qemu-utils amd64 1:2.11+dfsg-1ubuntu7.6 [868 kB]
Get:2 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 qemu-system-common amd64 1:2.11+dfsg-1ubuntu7.6 [661 kB]
Get:3 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 qemu-block-extra amd64 1:2.11+dfsg-1ubuntu7.6 [39.0 kB]
Get:4 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 qemu-kvm amd64 1:2.11+dfsg-1ubuntu7.6 [13.2 kB]
Get:5 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 qemu-system-x86 amd64 1:2.11+dfsg-1ubuntu7.6 [5201 kB]
Fetched 6782 kB in 1s (7023 kB/s)
(Reading database ... 86373 files and directories currently installed.)
Preparing to unpack .../qemu-utils_1%3a2.11+dfsg-1ubuntu7.6_amd64.deb ...
Unpacking qemu-utils (1:2.11+dfsg-1ubuntu7.6) over (1:2.11+dfsg-1ubuntu7.5) ...
Preparing to unpack .../qemu-system-common_1%3a2.11+dfsg-1ubuntu7.6_amd64.deb ...
Unpacking qemu-system-common (1:2.11+dfsg-1ubuntu7.6) over (1:2.11+dfsg-1ubuntu7.5) ...
Preparing to unpack .../qemu-block-extra_1%3a2.11+dfsg-1ubuntu7.6_amd64.deb ...
Unpacking qemu-block-extra:amd64 (1:2.11+dfsg-1ubuntu7.6) over (1:2.11+dfsg-1ubuntu7.5) ...
Preparing to unpack .../qemu-kvm_1%3a2.11+dfsg-1ubuntu7.6_amd64.deb ...
Unpacking qemu-kvm (1:2.11+dfsg-1ubuntu7.6) over (1:2.11+dfsg-1ubuntu7.5) ...
Preparing to unpack .../qemu-system-x86_1%3a2.11+dfsg-1ubuntu7.6_amd64.deb ...
Unpacking qemu-system-x86 (1:2.11+dfsg-1ubuntu7.6) over (1:2.11+dfsg-1ubuntu7.5) ...
Setting up qemu-block-extra:amd64 (1:2.11+dfsg-1ubuntu7.6) ...
Setting up qemu-utils (1:2.11+dfsg-1ubuntu7.6) ...
Processing triggers for man-db (2.8.3-2) ...
Setting up qemu-system-common (1:2.11+dfsg-1ubuntu7.6) ...
Setting up qemu-system-x86 (1:2.11+dfsg-1ubuntu7.6) ...
Setting up qemu-kvm (1:2.11+dfsg-1ubuntu7.6) ...

After the update:
PID 5482
Seccomp: 2
Seccomp: 2

Also worked with bigger configurations, setting verified.