Re: [PATCH v2 09/11] KVM: MMU: simplify mmu_need_write_protect

[Xiao Guangrong]

This is a multi-part message in MIME format.

On 12/24/2015 04:36 PM, Kai Huang wrote:
> On 12/23/2015 07:25 PM, Xiao Guangrong wrote:
> > Now, all non-leaf shadow page are page tracked, if gfn is not tracked
> > there is no non-leaf shadow page of gfn is existed, we can directly
> > make the shadow page of gfn to unsync
> >
> > Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/mmu.c | 26 ++++++++------------------
> >   1 file changed, 8 insertions(+), 18 deletions(-)
> >
> > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> > index 5a2ca73..f89e77f 100644
> > --- a/arch/x86/kvm/mmu.c
> > +++ b/arch/x86/kvm/mmu.c
> > @@ -2461,41 +2461,31 @@ static void __kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
> >       kvm_mmu_mark_parents_unsync(sp);
> >   }
> > -static void kvm_unsync_pages(struct kvm_vcpu *vcpu,  gfn_t gfn)
> > +static bool kvm_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn,
> > +                 bool can_unsync)
> >   {
> >       struct kvm_mmu_page *s;
> >       for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) {
> > +        if (!can_unsync)
> > +            return true;
> > +
> >           if (s->unsync)
> >               continue;
> >           WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
> >           __kvm_unsync_page(vcpu, s);
> >       }
> > +
> > +    return false;
> >   }
> I hate to say but it looks odd to me that kvm_unsync_pages takes a bool parameter called can_unsync,
> and return a bool (which looks like suggesting whether the unsync has succeeded or not). How about
> calling __kvm_unsync_pages directly in mmu_need_write_protect, and leave kvm_unsync_pages unchanged
> (or even remove it as looks it is used nowhere else) ? But again it's to you and Paolo.

Make senses, the updated version is attached, count you review it?