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

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Message-ID: <87k0exktsx.fsf@redhat.com>
Date:   Tue, 18 Jan 2022 15:22:22 +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

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)

-- 
Vitaly