Emulating graviton G3

[Robert Henry]

I cannot figure out how to make QEMU TCG emulate aarch64 Graviton G3.  I'm working against master/head of the QEMU source.

I come up with feature names by consulting https://marcin.juszkiewicz.com.pl/download/tables/arm-socs.html which is compendium of the /proc/cpuinfo info crowd sourced from linux running on real systems

I'm trying to either (a) add features to QEMU's '-cpu neoverse-n1,...' or (b) take features away from '-cpu max,...' 

Unfortunately, many names of implemented or unimplemented features are not known by the -cpu mechanism.  For example, from max I want to kill "smeb16f32", or from neoverse-n1 I want to add in "svei8mm", but neither name is known.  Indeed, the only names known by -cpu are those exposed via the qmp mechanism are of the form  "sveNNN" for vector bit width NNN.

Is there some trick I'm missing?