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

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Message-ID: <86b78fe0-7123-4534-6aaf-12bd30463665@redhat.com>
Date:   Fri, 28 Jan 2022 13:39:47 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...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

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, and feel free to send a 5.16 
backport too.

Paolo