Re: [PATCH 2/2] KVM: PPC: Book3S: Call into C interrupt handlers

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2012-04-27 at 01:30 +0200, Alexander Graf wrote:
> On 27.04.2012, at 01:12, Benjamin Herrenschmidt wrote:
> 
> > On Fri, 2012-04-27 at 00:24 +0200, Alexander Graf wrote:
> >> 
> >> This is to actually enable interrupts for real, regardless of ppc64
> >> and ppc32. In fact, the previous code was pretty buggy - it was
> >> running the handlers with interrupts disabled ;). 
> > 
> > They should be run with interrupts disabled.. tho both soft & hard.
> 
> The kvm_resched()? No, that one should be run with interrupts enabled - hard and soft :).

Ok, when you said "the handler" I thought you mean do_IRQ & co... those
must be run with IRQs off (and never enabled since taking the actual
exception).

> > You probably do want to call local_irq_disable() unconditionally anyway,
> > because on ppc32, that will give you the proper accounting vs. lockdep.
> 
> We already do __hard_irq_disable (which maps to local_irq_disable on ppc32)
> when entering the guest context and when leaving the intercept handler :).
> So that should be fine, no?

Well, __hard_irq_disable() isn't defined on ppc32 in hw_irq.h so if you
redefine it locally that's really gross :-) Also that means that from a
lockdep perspective you are running the entire guest with IRQs off ?
that doesn't sound right...

Cheers,
Ben.