Re: [Xen-devel] [PATCH V3] vmx/nmi: Do not use self_nmi() in VMEXIT handler

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 28/02/2013 16:17, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

>> Is this alternative that we might not process events for an unbounded time?
>> No, I guess not -- either we would interrupt the notifying IPI and we will
>> be IRETing into that IPI's handler, or the notifying IPI is delayed until
>> the NMI handler's IRET.
>> 
>> What about if the NMI handler itself raises an event (eg softirq)? Perhaps
>> there are no very essential ones of those?
> 
> We do raise PCI_SERR_SOFTIRQ, and the possibly injected NMI
> (to Dom0) might get slightly deferred too. The latter seems of
> little concern (Dom0 will get the event eventually). For the
> former, we might want to explicitly send a self-IPI with
> EVENT_CHECK_VECTOR following the raise_softirq()?

Or perhaps self-IPI on the NMI exit path if softirq_pending is non-zero?
Conservative but more generic.

 -- Keir



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