On Mon, Nov 14, 2022 at 04:39:40AM +0000, Li, Xin3 wrote: > > But what about NMIs, afaict this is all horribly broken for NMIs. > > > > So the whole VMX thing latches the NMI (which stops NMI recursion), right? > > > > But then you drop out of noinstr code, which means any random exception can > > happen (kprobes #BP, hw_breakpoint #DB, or even #PF due to random > > nonsense like *SAN). This exception will do IRET and clear the NMI latch, all > > before you get to run any of the NMI code. > > What you said here implies that we have this problem in the existing code. > Because a fake iret stack is created to call the NMI handler in the IDT NMI > descriptor, which lastly executes the IRET instruction. I can't follow; of course the IDT handler terminates with IRET, it has to no? And yes, the current code appears to suffer the same defect.
