Re: [Qemu-devel] [PATCH] target-ppc: Correct KVM synchronization for ppc_hash64_set_external_hpt()

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Apr 01, 2016 at 12:28:31PM +0200, Paolo Bonzini wrote:
> 
> 
> On 01/04/2016 05:52, David Gibson wrote:
> > This seems like the right minimal fix in the qemu-2.6 timeframe to fix
> > the actual bug.  However, longer term it seems like the correct thing
> > to do might be to set kvm_vcpu_dirty early in the reset path.  Thoughts?
> 
> Isn't it done already? vl.c does:
> 
>         pause_all_vcpus();
>         cpu_synchronize_all_states();
>         qemu_system_reset(VMRESET_REPORT);
>         resume_all_vcpus();


Huh.. now I'm really confused.  Given this I would indeed have
expected kvm_vpcu_dirty to be set in the reset path, but that would
make the cpu_synchronize_state() causing the problem to act as a
no-op, so it shouldn't be causing the problem.

Investigating...

> 
> Thanks,
> 
> Paolo
> 
> > diff --git a/target-ppc/mmu-hash64.c b/target-ppc/mmu-hash64.c
> > index 72c4ab5..caf41ce 100644
> > --- a/target-ppc/mmu-hash64.c
> > +++ b/target-ppc/mmu-hash64.c
> > @@ -283,8 +283,6 @@ void ppc_hash64_set_external_hpt(PowerPCCPU *cpu, void *hpt, int shift,
> >      CPUPPCState *env = &cpu->env;
> >      Error *local_err = NULL;
> >  
> > -    cpu_synchronize_state(CPU(cpu));
> > -
> >      if (hpt) {
> >          env->external_htab = hpt;
> >      } else {
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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