Re: [PATCH 1/12] KVM: X86: Fix when shadow_root_level=5 && guest root_level<4

[Sean Christopherson]

On Wed, Nov 24, 2021, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
> 
> If the is an L1 with nNPT in 32bit, the shadow walk starts with
> pae_root.
> 
> Fixes: a717a780fc4e ("KVM: x86/mmu: Support shadowing NPT when 5-level paging is enabled in host)

Have you actually run with 5-level nNPT?  I don't have access to hardware, at least
not that I know of :-)

I'm staring at kvm_mmu_sync_roots() and don't see how it can possibly work for
5-level nNPT with a 4-level NPT guest.