RE: [Xen-ia64-devel] lsapic deliver external IRQ

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

Magenheimer, Dan (HP Labs Fort Collins) wrote:
> The pending_interruption flag is critical for paravirtualized
> guests as it avoids many unnecessary privops/hypercalls when
> enabling interrupts.  Most of the time, when the rsm instruction
> is executed, there are no pending interrupts for the guest,
> so the paravirtualization of rsm psr.i in the current implementation
> is:
> 
>  tmp = shared_page.interrupt_enabled.
>  shared_page.interrupt_enabled = 1
>  if (!tmp && shared_page.pending_interruption) rsm psr.i***
A little bit confuse, is this for ssm psr.i or rsm psr.i?
Anyway, understand the situation. OK we can set this special flag when
there are pending IRQs.
> 
> *** or perhaps in a later implementation, do a (fast) hypercall
> 
> If your patch preserves this (or handles it better), yes,
> I would like to see it (though it may be better to submit
> it separate from the rest of the VT code so it can be
> reviewed easier).
> 
Eddie

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