Viridian disabled for Windows HVMs in R4.1?

In R4.1 I see that in /var/log/libvirt/libxl/win_vm_name.log, I see this entry:

“viridian”: “false”

for the windows HVMs that I was looking at.

  1. Would enabling Viridian under Xen 4.14, particularly for Windows HVMs, assist in reducing the number of hypercalls or other costly Ring transitions?

  2. e.g. Would this allows Windows HVMs to utilize (virtualized, not emulated) TSC directly? Or is this already happening? I see support for HPET, PIT and APIC timers listed in that file, but not TSC. Those tend to be substantially higher-cost (even when not emulated) than TSC.

  3. Was there an attempt to enable Viridian in qubes config, but it failed due to lack of libvirt support? Or is it not yet on the radar for qubes?


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Anyone from the qubesos / dev team have time to comment?