* Avi Kivity <[email protected]> wrote:
> From: Dor Laor <[email protected]>
>
> The current interrupt injection mechanism might delay an interrupt
> under the following circumstances:
>
> - if injection fails because the guest is not interruptible (rflags.IF clear,
> or after a 'mov ss' or 'sti' instruction). Userspace can check rflags,
> but the other cases or not testable under the current API.
> - if injection fails because of a fault during delivery. This probably
> never happens under normal guests.
> - if injection fails due to a physical interrupt causing a vmexit so that
> it can be handled by the host.
>
> in all cases the guest proceeds without processing the interrupt,
> reducing the interactive feel and interrupt throughput of the guest.
>
> This patch fixes the situation by allowing userspace to request an
> exit when the 'interrupt window' opens, so that it can re-inject the
> interrupt at the right time. Guest interactivity is very visibly
> improved.
Andrew, i'd argue for this to be included in v2.6.20, because it's an
obvious bugfix. I've tested this patch and it's included in current -rt
and i saw no regressions.
Acked-by: Ingo Molnar <[email protected]>
Ingo
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