how to increase vram in windows guest?

[gansteed]

Hello:
    I'm using kvm to host a windows 7 guest vm, I've install the latest
spice guest tools from
https://spice-space.org/download/windows/spice-guest-tools/spice-guest-tools-latest.exe,
and I've set video section like this:

<video>
  <model type="qxl" ram="262144" vram="262144" vram64="262144"
vgamem="131072" heads="1" primary="yes"/>
  <alias name="video0"/>
  <address type="pci" domain="0x0000" bus="0x00" slot="0x01"
function="0x0"/>
</video>

but the graphics in windows guest is laggy, I' found that the guest have
only use 16MB as vram:

How can I increase the real usage of vram in the windows guest vm?
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