Re: [PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi_irq() for NMI/IRQ reinjection

H. Peter Anvin
2022-11-11T09:30:30Z

On November 11, 2022 1:19:23 AM PST, Peter Zijlstra <peterz@infradead.org> wrote:
>On Thu, Nov 10, 2022 at 08:53:09PM +0000, Sean Christopherson wrote:
>> On Thu, Nov 10, 2022, Li, Xin3 wrote:
>
>> > > > + * call thus the values in the pt_regs structure are not used in
>> > > > + * executing NMI/IRQ handlers,
>> > >
>> > > Won't this break stack traces to some extent?
>> > >
>> >
>> > The pt_regs structure, and its IP/CS, is NOT part of the call stack, thus
>> > I don't see a problem. No?
>
>I'm not sure what Xin3 is trying to say, but NMI/IRQ handers use pt_regs
>a *LOT*. pt_regs *MUST* be correct.

What is "correct" in this context? Could you describe what aspects of the register image you rely on, and what you expect them to be? Currently KVM basically stuff random data into pt_regs; this at least makes it explicitly zero.