<video>
<model type="qxl" ram="65536" vram="65536" vgamem="16384" heads="1" primary="yes"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
</video><video>
<model type="qxl" ram="65536" vram="65536" vgamem="65536" heads="2" primary="yes"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
</video>According to the post, vgamem="32768" may work too.
https://stackoverflow.com/a/55117033/811479
On another virtual machine, running Pop!_OS, I’ve seen this work too…
<video>
<model type="qxl" ram="131072" vram="131072" vgamem="32768" heads="1" primary="yes"/>
<alias name="video0"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
</video>