On Tue, Jun 11, 2024, Oliver Upton wrote:
> On Tue, Jun 11, 2024 at 09:49:59AM -0700, James Houghton wrote:
> > I think consolidating the callbacks is cleanest, like you had it in
> > v2. I really wasn't sure about this change honestly, but it was my
> > attempt to incorporate feedback like this[3] from v4. I'll consolidate
> > the callbacks like you had in v2.
>
> My strong preference is to have the callers expectations of the
> secondary MMU be explicit. Having ->${BLAH}_fast_only() makes this
> abundantly clear both at the callsite and in the implementation.
Partially agreed. We don't need a dedicated mmu_notifier API to achieve that
for the callsites, e.g. ptep_clear_young_notify() passes fast_only=false, and a
new ptep_clear_young_notify_fast_only() does the obvious.
On the back end, odds are very good KVM is going to squish the "fast" and "slow"
paths back into a common helper, so IMO having dedicated fast_only() APIs for the
mmu_notifier hooks doesn't add much value in the end.
I'm not opposed to dedicated hooks, but I after poking around a bit, I suspect
that passing a fast_only flag will end up being less cleaner for all parties.
