On Tue, May 08, 2012 at 12:09:38PM +0300, Avi Kivity wrote:
> On 05/08/2012 04:55 AM, Marcelo Tosatti wrote:
> > > > Yes, so, we can change kvm_mark_tlb_dirty to:
> > > >
> > > > +static inline void kvm_mark_tlb_dirty(struct kvm *kvm)
> > > > +{
> > > > + /*
> > > > + * Make any changes to the page tables visible to remote flushers.
> > > > + */
> > > > + smb_mb();
> > > > + kvm->tlb_state.dirtied_count++;
> > > > +}
> > > >
> > >
> > > Yes. We'll have to change it again if we ever dirty sptes outside the
> > > lock, but that's okay.
> >
> > Please don't. There are readers outside mmu_lock, so it should be
> > atomic.
>
> Why does it need to be atomic? All it needs is to be properly barriered
> (provided by spin_unlock(mmu_lock).
It does not _need_ to be atomic. It is easier to verify and self
contained.
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