[RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts
Scott Wood
scottwood at freescale.com
Fri May 10 07:27:36 EST 2013
On 05/09/2013 07:37:42 AM, Benjamin Herrenschmidt wrote:
> On Thu, 2013-05-09 at 17:44 +0800, tiejun.chen wrote:
> >
> > Actually in the case GS=1 even if EE=0, EXT/DEC/DBELL still occur
> as I
> > recall.
>
> Only if directed to the hypervisor.
This is always the case with KVM, right? At least on booke...
> > > Case 1)
> > > -> Local_irq_disable() will set soft_enabled = 0
> > > -> Now Externel interrupt happens, there we set PACA_IRQ_EE in
> > irq_happened, Also clears EE in SRR1 and rfi. So interrupts are hard
> > disabled. No more other interrupt gated by MSR.EE can happen. Looks
> > like the idea here is to not let a device keep on inserting
> interrupt
> > till the interrupt condition on device is cleared, right?
>
> The external interrupt line is level sensitive normally, so we have to
> mask MSR:EE in that case or the interrupt would keep re-occurring
> (note
> that FSL has this concept of auto-acked interrupts via the on die MPIC
> for which you can potentially use PACA_IRQ_EE_EDGE instead and avoid
> having to mask MSR:EE).
Note that if we do this, we can no longer leave the interrupt vector in
EPR, and would have to track (potentially multiple different) pending
external interrupts in software.
-Scott
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