Re: [PATCH] Arm: tidy page_get_owner_and_nr_reference()

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 02/07/2025 14:37, Jan Beulich wrote:
> On 02.07.2025 15:18, Julien Grall wrote:
> > On 02/07/2025 14:06, Jan Beulich wrote:
> > > When the bumping by <nr> (instead of just 1) was introduced, a comment
> > > was left untouched, and a bogus ASSERT_UNREACHABLE() was inserted. That
> > > code path can in principle be taken (depending on configuration coming
> > > from the outside), and we shouldn't assert anything we didn't check
> > > elsewhere.
> > I suggested to add the ASSERT_UNREACHABLE (see [1]). My take is the
> > overflow is not something that should happen and it is good to be able
> > to catch very clearly in debug build.
> But catching an anomalous entry in DT (which aiui the values come from,
> even if perhaps indirectly) isn't going to depend on people using debug
> builds. It depends on what DT blobs they use. And issues there shouldn't
> be checked by assertions, as those blobs live outside of Xen.
I agree we probably want check upfront. But I still don't think we want 
to remove this ASSERT_UNREACHABLE().
By the way, I am not asking you to add those checks.

Cheers,

--
Julien Grall