Re: [PATCH v3 0/5] KVM: nVMX: Fix Windows 11 + WSL2 + Enlightened VMCS

[Paolo Bonzini]

On 1/18/22 15:22, Vitaly Kuznetsov wrote:
> Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:
>
> > Changes since v2 [Sean]:
> > - Tweak a comment in PATCH5.
> > - Add Reviewed-by: tags to PATCHes 3 and 5.
> >
> > Original description:
> >
> > Windows 11 with enabled Hyper-V role doesn't boot on KVM when Enlightened
> > VMCS interface is provided to it. The observed behavior doesn't conform to
> > Hyper-V TLFS. In particular, I'm observing 'VMREAD' instructions trying to
> > access field 0x4404 ("VM-exit interruption information"). TLFS, however, is
> > very clear this should not be happening:
> >
> > "Any VMREAD or VMWRITE instructions while an enlightened VMCS is active is
> > unsupported and can result in unexpected behavior."
> >
> > Microsoft confirms this is a bug in Hyper-V which is supposed to get fixed
> > eventually. For the time being, implement a workaround in KVM allowing
> > VMREAD instructions to read from the currently loaded Enlightened VMCS.
> >
> > Patches 1-2 are unrelated fixes to VMX feature MSR filtering when eVMCS is
> > enabled. Patches 3 and 4 are preparatory changes, patch 5 implements the
> > workaround.
>
> Paolo,
>
> would it be possible to pick this up for 5.17? Technically, this is a
> "fix", even if the bug itself is not in KVM)

Yes, it is.  I have queued the patch, and feel free to send a 5.16 
backport too.

Paolo