Re: [PATCH v2] KVM: Implement support for the RH bit

Gleb Natapov
2011-09-02T15:03:45Z

On Fri, Sep 02, 2011 at 04:52:51PM +0200, Jan Kiszka wrote:
> >> That's debatable. delivery_mode == APIC_DM_LOWEST includes this target
> >> selection, but also more. I have a bad feeling when we just overwrite
> >> delivery_mode as defined by the MSI data field instead of only patching
> >> kvm_irq_delivery_to_apic or kvm_is_dm_lowest_prio - if required.
> >>
> > Patching them how? To behave exactly like delivery_mode == APIC_DM_LOWEST in
> > case RH bit is set? Then setting delivery_mode to APIC_DM_LOWEST will
> > achieve the same goal.
>
> /Wrt selecting the target CPU, but not regarding the vector type
> delivered to that CPU (think of obscure things like RH=1,
> delivery_mode=APIC_DM_NMI). If RH=1 only meant hard-wiring delivery_mode
> to single value, then this would be redundant encoding. And that's
> always suspicious (unless there is legacy involved).
>
Hmm, good point.

--
Gleb.