Comment 3 for bug 1866870

I first checked the related known fixes from the old case that is linked.
Just in case if we might miss one in Ubuntu 20.04 that you are using.

Kernel:
=> https://marc.info/?l=kvm&m=155085391830663&w=2
Tested and verified https://bugs.launchpad.net/qemu/+bug/1813165/comments/13
This got upstream and is in:
$ git describe --contains ad7dc69aeb231
v5.0-rc8~1^2~2
That we'd clearly have in Focal being on 5.4

qemu
https://git.qemu.org/?p=qemu.git;a=commit;h=9c1f8f4493e8355d0e48f7d1eebdf86893ba082d
Other fixes related to the topic are in qemu 2.8

On seabios disabling of SMM
- https://bugzilla.redhat.com/show_bug.cgi?id=1378006
- https://bugzilla.redhat.com/show_bug.cgi?id=1464654#c21
The following is from >=1.12.0-1 (was enabled by default before)
There is a small (for old qemu) and large binary (new qemu):
 42 build/bios.bin:
 43 # A stripped-down version of bios, to fit in 128Kb, for qemu <= 1.7
 44 »···$(call build-bios,bios,QEMU=y ROM_SIZE=128 PVSCSI=n BOOTSPLASH=n XEN=n USB_OHCI=n USB_XHCI=n USB_UAS=n SDCARD=n TCGBIOS=n MPT_SCSI=n NVME=n USE_SMM=n VGAHOOKS=n)
 45 build/bios-256k.bin:
 46 »···$(call build-bios,bios,QEMU=y ROM_SIZE=256)

Note: if we are out of options we could try testing to set USE_SMM=n here, but lets check other details first.

But as already explained on the linked bug 1813165:
"If you're seeing "KVM internal error. Suberror: 1" it can be multiple things, not necessarily the same bug."