Information can be put into dmi tables via some qemu-system hosts (x86_64 and aarch64). That information is exposed in Linux under /sys/class/dmi/id and can be read with dmidecode. The names are very annoyingly inconsistent. The point of this doc is to map them.
See qemu-system-x86_64 --help for the fields that qemu will accept.
qemu smbios flags vary with qemu version.
Example qemu cmdline:
qemu-system-x86_64 -smbios type=,field=value[,...]