On Fri, Feb 25, 2022 at 7:13 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 2/25/22 16:12, Xiaoyao Li wrote: > >>>> > >>> > >>> I don't like the idea of making things up without notifying userspace > >>> that this is fictional. How is my customer running nested VMs supposed > >>> to know that L2 didn't actually shutdown, but L0 killed it because the > >>> notify window was exceeded? If this information isn't reported to > >>> userspace, I have no way of getting the information to the customer. > >> > >> Then, maybe a dedicated software define VM exit for it instead of > >> reusing triple fault? > >> > > > > Second thought, we can even just return Notify VM exit to L1 to tell L2 > > causes Notify VM exit, even thought Notify VM exit is not exposed to L1. > > That might cause NULL pointer dereferences or other nasty occurrences. Could we synthesize a machine check? I haven't looked in detail at the MCE MSRs, but surely there must be room in there for Intel to reserve some encodings for synthesized machine checks.
