[PATCH] kho: add support for deferred struct page init

[Pasha Tatashin]

On Tue, Dec 30, 2025 at 11:16 AM Mike Rapoport <rppt at kernel.org> wrote:
>
> On Tue, Dec 30, 2025 at 11:05:05AM -0500, Pasha Tatashin wrote:
> > On Mon, Dec 29, 2025 at 4:03 PM Pratyush Yadav <pratyush at kernel.org> wrote:
> > >
> > > The magic is purely sanity checking. It is not used to decide anything
> > > other than to make sure this is actually a KHO page. I don't intend to
> > > change that. My point is, if we make sure the KHO pages are properly
> > > initialized during MM init, then restoring can actually be a very cheap
> > > operation, where you only do the sanity checking. You can even put the
> > > magic check behind CONFIG_KEXEC_HANDOVER_DEBUG if you want, but I think
> > > it is useful enough to keep in production systems too.
> >
> > It is part of a critical hotpath during blackout, should really be
> > behind CONFIG_KEXEC_HANDOVER_DEBUG
>
> Do you have the numbers? ;-)

The fastest reboot we can achieve is ~0.4s on ARM
(shutdown+purgatory+boot), let's not add anything to regress, as every
microsecond counts during blackout.

Pasha