Re: [kvm-ppc-devel] guest panic fixed

[Hollis Blanchard <hollisb@us.ibm.com>]

On Thu, 2008-03-20 at 09:32 +0100, Christian Ehrhardt wrote:
> Hollis Blanchard wrote:
> > Thanks to some excellent debugging by Christian, we found the cause of
> > our annoying guest panics. We had not implemented exception priorities
> > (my bad), so a userspace ITLB miss was being delivered immediately after
> > entry to the decrementer interrupt vector. Patch follows,
> > http://penguinppc.org/~hollisb/kvm/ updated.
> > 
> > NFS root with virtio-net still doesn't work for me, but it doesn't
> > crash. :)
> > 
> > @@ -65,12 +68,14 @@ extern void kvmppc_44x_tlb_trace(int act
> > 
> >  static inline void kvmppc_queue_exception(struct kvm_vcpu *vcpu, int exception)
> >  {
> > -	set_bit(exception, &vcpu->arch.pending_exceptions);
> > +	unsigned int priority = exception_priority[exception];
> > +	set_bit(priority, &vcpu->arch.pending_exceptions);
> 
> saves a line and a local var on irq path (well the compiler might optimize that anyway)
> 	set_bit(exception_priority[exception], &vcpu->arch.pending_exceptions);

The compiler should handle it; you can examine the disassembly if you're
worried.

-- 
Hollis Blanchard
IBM Linux Technology Center


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