Re: [PATCH v4 00/27] Implementing a MSHV (Microsoft Hypervisor) accelerator

[Magnus Kulke <magnuskulke@linux.microsoft.com>]

On Thu, Oct 02, 2025 at 10:30:56AM +0200, Philippe Mathieu-Daudé wrote:
> Due to my generic work on accelerators, I'll have to refactor these
> patches. Obviously I don't want to break your implementation! Can
> you add some (functional?) tests? Ideally we should be running
> tests on our CI to ensure code doesn't bitrot.
> 
> Regards,
> 
> Phil.

Hey Phil,

yes, that's a good point. I assume for functional tests we
will face the challenge those will require external infra, because
eventually there needs to be a HyperV Hypervisor running somewhere.

Is there any precedent/prior art in QEMU (e.g. for HVF or WHPX) that we
could follow?

FWIW, in smoke tests for the patch series I've been using a nested
HyperV hypervisor that is shipped as dll and made available as UEFI
protocol to the MSHV driver (I _think_ that is how it works, I'm a
bit out of my depth here since I don't know how those things are
glued together in detail).

For reference: https://github.com/mkulke/qemu/actions/runs/18187719634

There will be other virt topologies supported by the MSHV driver and
the nested option is not upstreamed to mainline yet. However, from
QEMU's perspective those topologies do not matter, they share the same
ABI of the kernel driver.

So we could do something similar, provide/maintain a VM on Azure with a
similar nested HyperV hypervisor configuration that we can used for
testing. Would this make sense?

Best,

magnus