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

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Message-ID: <87wnikeyr9.fsf@redhat.com>
Date:   Fri, 28 Jan 2022 15:11:22 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v3 0/5] KVM: nVMX: Fix Windows 11 + WSL2 + Enlightened VMCS

Paolo Bonzini <pbonzini@...hat.com> writes:

> On 1/18/22 15:22, Vitaly Kuznetsov wrote:
>> Vitaly Kuznetsov <vkuznets@...hat.com> 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

Thanks!

> and feel free to send a 5.16 backport too.

I see your pull request to Linus, will send the backport when it lands.
In fact, all 5 patches apply to 5.16 without issues but I guess stable@
tooling won't pick them up automatically.

-- 
Vitaly