Re: [Qemu-devel] [PATCH] kvm/apic: fix 2.2->2.1 migration

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> 
> 
> On 12/12/2014 18:30, Dr. David Alan Gilbert wrote:
> > OK, let me just check that I get this....
> > 
> > It gets reset to 0 already in kvm_apic_realize
> 
> (before this patch -- after this patch it's only done in reset)
> 
> > then we do the common init
> 
> Then as part of starting up auxiliary processors we send an INIT
> interrupt, that resets the APIC and...
> 
> > that sets it to !bsp - so 1 for most CPUs
> > then you're adding this so that a specific APIC implementation (kvm)
> > can nobble it back to 0 again?
> 
> Yes.  That's needed because this APIC implementation does not use the
> field at all.
> 
> > and on the load side it's forced to zero by apic_pre_load.
> 
> Yes.  That's the common case for the !APIC implementation because it
> gets to zero as soon as te OS starts.

OK; yep, that's OK.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> 
> Paolo
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK