Re: [PATCH v2] Argo: don't obtain excess page references

[Christopher Clark <christopher.w.clark@xxxxxxxxx>]

On Sun, Feb 18, 2024 at 10:01 AM Julien Grall <julien@xxxxxxx> wrote:
>
> Hi Jan,
>
> On 14/02/2024 10:12, Jan Beulich wrote:
> > find_ring_mfn() already holds a page reference when trying to obtain a
> > writable type reference. We shouldn't make assumptions on the general
> > reference count limit being effectively "infinity". Obtain merely a type
> > ref, re-using the general ref by only dropping the previously acquired
> > one in the case of an error.
> >
> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
>
> > ---
> > I further question the log-dirty check there: The present P2M type of a
> > page doesn't really matter for writing to the page (plus it's stale by
> > the time it is looked at). Instead I think every write to such a page
> > needs to be accompanied by a call to paging_mark_dirty().
>
> I agree with that.

Adding OpenXT mailing list as I have found that I have not had the
time available that I had hoped for to spend on reviewing this Argo
change, and to provide opportunity for downstream feedback.

Link to the posted patch (start of this thread):
https://lists.xenproject.org/archives/html/xen-devel/2024-02/msg00858.html

Christopher

>
> Cheers,
>
> --
> Julien Grall