> >> >+ else if (is_nm_fault(intr_info) && > >> >+ vcpu->arch.guest_fpu.fpstate->xfd) > >> > >> does this necessarily mean the #NM is caused by XFD? > > > >Then the event data should be 0. Or I missed something obvious? I.e., > >it can be easily differentiated and we should just explicitly set it to > >0. > > vcpu->arch.guest_fpu.fpstate->xfd just means the guest is enabling XFD. > I don't think we can conclude that this #NM is caused by XFD only from this. i.e., > there may be some false positives. Then we should get 0 in event data. Otherwise, it is a bug in how we deal with IA32_XFD_ERR MSR, w/ or w/o FRED. > >> >+ default: > >> >+ WARN_ON(event_data != 0); > >> > >> I am not sure if this WARN_ON() can be triggeded by nested VMX. It is > >> legitimate for L1 VMM to inject any event w/ an event_data. > >> > >> FRED spec says: > >> > >> Section 5.2.1 specifies the event data that FRED event delivery of > >> certain events saves on the stack. When FRED event delivery is used > >> for an event injected by VM entry, the event data saved is the value > >> of the injected-event-data field in the VMCS. This value is used > >> instead of what is specified in Section 5.2.1 and is done for __ALL__ > >> injected events using FRED event delivery > > > >5.2.1 Saving Information on the Regular Stack also says: > >- For any other event, the event data are not currently defined and > >will > > be zero until they are. > > > >Or you mean something else? > > IIUC, L1 KVM can inject a nested exception whose vector isn't #DB, or #NM or #PF > with a non-zero event_data to L2. No, this is not allowed. > If delivering the nested exception causes a VM- > exit to L0 KVM, the assertion that event_data is always 0 for vectors other than > #DB/#NM/#PF fails.
