Re: [PATCH 1/2] KVM: Introduce kvm_arch_memslots_updated()

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Thu, 4 Jul 2013 12:53:15 +0300
Gleb Natapov <gleb@redhat.com> wrote:

> On Thu, Jul 04, 2013 at 01:40:29PM +0900, Takuya Yoshikawa wrote:
> > This is called right after the memslots is updated, i.e. when the result
> > of update_memslots() gets installed in install_new_memslots().  Since
> > the memslots needs to be updated twice when we delete or move a memslot,
> > kvm_arch_commit_memory_region() does not correspond to this exactly.
> > 
> > In the following patch, x86 will use this new API to check if the mmio
> > generation has reached its maximum value, in which case mmio sptes need
> > to be flushed out.
> > 
> > Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
> > ---
> >  Removed the trailing space after "return old_memslots;" at this chance.
> > 
> >  arch/arm/kvm/arm.c         |    4 ++++
> >  arch/ia64/kvm/kvm-ia64.c   |    4 ++++
> >  arch/mips/kvm/kvm_mips.c   |    4 ++++
> >  arch/powerpc/kvm/powerpc.c |    4 ++++
> >  arch/s390/kvm/kvm-s390.c   |    4 ++++
> >  arch/x86/kvm/x86.c         |    4 ++++
> >  include/linux/kvm_host.h   |    1 +
> >  virt/kvm/kvm_main.c        |    5 ++++-
> >  8 files changed, 29 insertions(+), 1 deletion(-)

> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index e3aae6d..1c1e9de 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -498,6 +498,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> >  void kvm_arch_free_memslot(struct kvm_memory_slot *free,
> >  			   struct kvm_memory_slot *dont);
> >  int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages);
> > +void kvm_arch_memslots_updated(struct kvm *kvm);
> We can define empty function here like this:
> #ifdef __KVM_HAVE_MEMSLOT_UPDATE
>  void kvm_arch_memslots_updated(struct kvm *kvm);
> #else
>  static void kvm_arch_memslots_updated(struct kvm *kvm)
>  {
>  }
> #endif
> 
> and make x86.c define __KVM_HAVE_MEMSLOT_UPDATE.
> 
> But I am fine with your approach too. Do other arch maintainers have any
> preferences here?

I don't really have a strong preference either way, so

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

for the current approach.