Re: Xen 4.18.5 PV dbregs fail

[Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>]

On Mon, May 26, 2025 at 10:17:06PM +0100, Andrew Cooper wrote:
> On 26/05/2025 10:10 pm, Manuel Bouyer wrote:
> > On Mon, May 26, 2025 at 10:56:41PM +0200, Manuel Bouyer wrote:
> >> On Mon, May 26, 2025 at 09:30:53PM +0100, Andrew Cooper wrote:
> >>> On 26/05/2025 9:13 pm, Manuel Bouyer wrote:
> >>>> On Mon, May 26, 2025 at 07:50:14PM +0100, Andrew Cooper wrote:
> >>>>> [...]
> >>>>> Well, that range does include the aforementioned commit.
> >>>>>
> >>>>> Can you bisect around d32c77f471fb8400b6512c171a14cdd58f04f0a3 which is
> >>>>> the backport of ^ in 4.18 ?
> >>>> Sure,
> >>>> with 0d5f15e and d32c77f the test pass, with cecee35 it fails.
> >>>>
> >>> Oh interesting, so the basic forwarding of #DB back into a guest
> >>> (d32c77f) works fine, but the changes to emulated debug exceptions
> >>> (cecee35) break.
> >>>
> >>> Anyway, I think I've spotted a logical error.  We do indeed end up
> >>> calling x86_merge_dr6() twice, because of the TODO just out of context. 
> >>> Does this help?
> >> Yes, it works for cecee35; now testing with 4.18.5
> > yes, it works with 4.18.5 too. All dbreg-related tests now pass again
> > thanks !
> >
> 
> Sorry I screwed it up so badly, and apparently also my own testing...
> 
> May I take that as a Tested-by tag on the patch then?

Sure

> 
> I'll get the fix merged once it's been reviewed, but 4.18 is in
> security-only support right now and is unlikely to get this as a backport.
> 
> Are you able to take the patch logically for NetBSD?

Yes, I can add it to pkgsrc, no problem.

I need to package 4.20 too ...

-- 
Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>
     NetBSD: 26 ans d'experience feront toujours la difference
--