Re: [PATCH v7 00/24] WHPX support for Arm

Mohamed Mediouni
2025-10-17T10:56:35Z

> On 17. Oct 2025, at 11:59, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Thu, 16 Oct 2025 at 17:56, Mohamed Mediouni <mohamed@unpredictable.fr> wrote:
>>
>> Link to branch: https://github.com/mediouni-m/qemu whpx (tag for this submission: whpx-v6)
>>
>> Missing features:
>> - PSCI state sync with Hyper-V
>> - Interrupt controller save-restore
>> - SVE register sync
>
> The interrupt-controller save-state we can probably live
> without if we have a migration-blocker for it, but the
> SVE and PSCI state sync missing seems like it would be
> a source of bugs?
For SVE it’s dealt with by disabling it. There’s no consumer Windows on arm64 hardware with SVE available for sale right now unfortunately - but it’s coming in Q1 next year.

For PSCI state sync it’s… well, brittle on the Hyper-V side (with opaque, currently undocumented flags). Doing it would fix reboots though.

Note that Hyper-V doesn't cause VM exits for PSCI calls today, even if it’s to bring up a CPU.

>> Known bugs:
>> - reboots when multiple cores are enabled are currently broken
>> - U-Boot still doesn't work (hangs when trying to parse firmware) but EDK2 does.
>
> You need to fix your known bugs before we take this, I think...

I can try to address the first one/on the cards but the second one would probably come later (if it’s not actually due to a platform bug…) .

-Mohamed
> thanks
> -- PMM
>