Re: [RFC PATCH 0/3] KVM: Dirty page logging for guest_memfd-only memslots

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi,

On Fri, Aug 14, 2026 at 09:04:46AM -0700, Sean Christopherson wrote:
> On Fri, Aug 14, 2026, Alexandru Elisei wrote:
> > On Fri, Aug 14, 2026 at 06:03:54AM -0700, Sean Christopherson wrote:
> > > > That would be in contrast to user space having to guess that page migration on
> > > > the current hardware with the current guest_memfd implementation does not
> > > > support page migration, to then disable exactly that.
> > 
> > If guest_memfd picks up support for another feature that might lead to
> > memory being unmapped from stage 2 without userspace initiating it, would
> > you be ok with that feature being gated by another guest_memfd flag?
> 
> Yes, absolutely.  FWIW, if I get my way and reclaim is driven by userspace, then
> hopefully such a feature never comes along.  But if guest_memfd does gain some
> feature that triggers invalidations, then yeah, at the very least it would need
> to have some knowledge of whether or not the associated VM supports said feature.
> 
> > I get the feeling we're all on the same page, that guest_memfd will support
> > a mode where memory isn't unmapped from stage 2, and right now the
> > discussion is more about how that will be implemented.
> 
> Ya.

That's great, thanks for confirming.

Alex