linux-kernel - [PATCH v2 0/5] KVM: nVMX: Fix Windows 11 + WSL2 + Enlightened VMCS

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Date:   Fri,  7 Jan 2022 11:28:54 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, 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
Subject: [PATCH v2 0/5] KVM: nVMX: Fix Windows 11 + WSL2 + Enlightened VMCS

Changes since v1 [Sean]:
- Rename vmcs12_field_offset_table -> vmcs12_field_offsets, 
 vmcs12_field_offset()->get_vmcs12_field_offset()
- Forbid VMREAD when "current_vmptr == INVALID_GPA && evmptr_is_valid() &&
  is_guest_mode()".

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.

Vitaly Kuznetsov (5):
  KVM: nVMX: Also filter MSR_IA32_VMX_TRUE_PINBASED_CTLS when eVMCS
  KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER
  KVM: nVMX: Rename vmcs_to_field_offset{,_table}
  KVM: nVMX: Implement evmcs_field_offset() suitable for handle_vmread()
  KVM: nVMX: Allow VMREAD when Enlightened VMCS is in use

 arch/x86/kvm/vmx/evmcs.c  |  4 +--
 arch/x86/kvm/vmx/evmcs.h  | 48 +++++++++++++++++++++++++------
 arch/x86/kvm/vmx/nested.c | 59 +++++++++++++++++++++++++++------------
 arch/x86/kvm/vmx/vmcs12.c |  4 +--
 arch/x86/kvm/vmx/vmcs12.h |  6 ++--
 5 files changed, 87 insertions(+), 34 deletions(-)

-- 
2.33.1