Re: [PATCH v2 0/2] KVM: nVMX: Don't let L2's LMSW modify CR0 bits owned by L1

From: Sean Christopherson

Date: Fri Oct 30 2026 - 14:51:02 EST


On Thu, Oct 29, 2026, Mahmoud Abumandour wrote:
> When L2's LMSW exits to L0 but not to L1, KVM emulates it with
> kvm_lmsw(), which ignores vmcs12's CR0 guest/host mask, so L2 can change
> CR0 bits that L1 owns.
>
> v2:
> - Patch 2: order the CR0 store before FNOP and check L2's whole CR0.

I'll send a v3, I already spent an absurd amount of time figuring all of this
out. I really hate x86 sometimes.