Re: [PATCH v2 06/12] KVM: mark kvm->buses as empty once they were destroyed

[Marcelo Tosatti <mtosatti@redhat.com>]

On Wed, Mar 25, 2015 at 05:09:13PM +0000, Marc Zyngier wrote:
> On 23/03/15 15:58, Andre Przywara wrote:
> > In kvm_destroy_vm() we call kvm_io_bus_destroy() pretty early,
> > especially before calling kvm_arch_destroy_vm(). To avoid
> > unregistering devices from the already destroyed bus, let's mark
> > the bus with NULL to let other users know it has been destroyed
> > already.
> > This avoids a crash on a VM shutdown with the VGIC using the
> > kvm_io_bus later (the unregistering is in there to be able to roll
> > back a faulting init).
> > 
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> 
> That seems sensible, but I don't see why nobody else hits that. What are
> we doing differently?
> 
> Otherwise,
> 
> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
> 
> Paolo, Marcelo, can we have your Ack on this?
> 
> Thanks,
> 
> 	M.
> 
> > ---
> >  virt/kvm/kvm_main.c |    4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 8c7ab0b..6f164eb 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -604,8 +604,10 @@ static void kvm_destroy_vm(struct kvm *kvm)
> >  	list_del(&kvm->vm_list);
> >  	spin_unlock(&kvm_lock);
> >  	kvm_free_irq_routing(kvm);
> > -	for (i = 0; i < KVM_NR_BUSES; i++)
> > +	for (i = 0; i < KVM_NR_BUSES; i++) {
> >  		kvm_io_bus_destroy(kvm->buses[i]);
> > +		kvm->buses[i] = NULL;
> > +	}
> >  	kvm_coalesced_mmio_free(kvm);
> >  #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
> >  	mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
> > 
> 
> 
> -- 
> Jazz is not dead. It just smells funny...

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>