On Wed, Sep 14, 2016 at 05:22:40PM +1000, David Gibson wrote:
> On Wed, Sep 14, 2016 at 03:12:43PM +0800, Peter Xu wrote:
> > On Wed, Sep 14, 2016 at 03:55:28PM +1000, David Gibson wrote:
> >
> > [...]
> >
> > > > -static void vtd_iommu_notify_started(MemoryRegion *iommu)
> > > > +static void vtd_iommu_notify_flag_changed(MemoryRegion *iommu,
> > > > + IOMMUNotifierFlag old,
> > > > + IOMMUNotifierFlag new)
> > > > {
> > > > VTDAddressSpace *vtd_as = container_of(iommu, VTDAddressSpace,
> > > > iommu);
> > >
> > > Shouldn't this have a sanity check that the new flags doesn't include
> > > MAP actions?
> >
> > See your r-b for patch 3, thanks! So skipping this one.
> >
> > [...]
> >
> > > > +static void spapr_tce_notify_flag_changed(MemoryRegion *iommu,
> > > > + IOMMUNotifierFlag old,
> > > > + IOMMUNotifierFlag new)
> > > > +{
> > > > + if (old == IOMMU_NOTIFIER_NONE && new == IOMMU_NOTIFIER_ALL) {
> > > > + spapr_tce_notify_started(iommu);
> > > > + } else if (old == IOMMU_NOTIFIER_ALL && new ==
> > > > IOMMU_NOTIFIER_NONE) {
> > > > + spapr_tce_notify_stopped(iommu);
> > > > + }
> > >
> > > This is wrong. We need to do the notify_start and stop actions if
> > > *any* bits are set in the new/old flags, not just if all of them are
> > > set.
> >
> > Power should need both, right? I can switch all
> >
> > "== IOMMU_NOTIFIER_ALL"
> >
> > into:
> >
> > "!= IOMMU_NOTIFIER_NONE"
>
> Yes, that should be right.
>
> > in the next version if you like, but AFAICT they are totally the
> > same.
>
> Again, only if you assume things about how the notifiers will be used,
> which is not a good look when designing an interface.
This should not be related to the interface at all?
I was based on the assumption that "Power cannot support either one of
MAP/UNMAP, but only if both exist". To be more specific, we possibly
can have this at the beginning of flags_changed():
assert(old == IOMMU_NOTIFIER_NONE || old == IOMMU_NOTIFIER_ALL);
assert(new == IOMMU_NOTIFIER_NONE || new == IOMMU_NOTIFIER_ALL);
To make sure nothing will go wrong.
Thanks,
-- peterx
