Re: port-xen/57199: Pure PVH i386 guests hang on disk activity

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Jul 15, 2024 at 03:00:03PM -0400, Brad Spencer wrote:
> Taylor R Campbell <riastradh%NetBSD.org@localhost> writes:
> 
> > The following reply was made to PR kern/57199; it has been noted by GNATS.
> >
> > From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
> > To: Brad Spencer <brad%anduin.eldar.org@localhost>
> > Cc: bouyer%antioche.eu.org@localhost, gnats-bugs%NetBSD.org@localhost,
> > 	netbsd-bugs%NetBSD.org@localhost, gdt%lexort.com@localhost
> > Subject: Re: port-xen/57199: Pure PVH i386 guests hang on disk activity
> > Date: Mon, 15 Jul 2024 18:52:14 +0000
> >
> >  > Date: Mon, 15 Jul 2024 14:31:41 -0400
> >  > From: Brad Spencer <brad%anduin.eldar.org@localhost>
> >  > 
> >  > b) I will test Taylor's patch on the DOMU.  Doing that on the DOM0 is
> >  > probably not something I can manage right now.
> >  
> >  I should clarify: I suspect this may be needed on the dom0, but only
> >  if the dom0 _also_ runs uniprocessor, i.e., single-vCPU.
> >  
> >  If you can run crash(8) or enter ddb on the dom0, you can check like
> >  so:
> >  
> >  # crash
> >  Crash version 10.0_STABLE, image version 10.0.
> >  WARNING: versions differ, you may not be able to examine this image.
> >  Kernel compiled without options LOCKDEBUG.
> >  Output from a running system is unreliable.
> >  crash> x/i membar_sync,3
> >  _membar_enter:  lock addq       $0,fffffffffffffff8 (%rsp)
> >  _membar_enter+0x7:      ret
> >  _membar_enter+0x8:      nopl
> >  
> >  If it says `lock addq' or `lock addl', you're good.  If it's just
> >  `addq' or `addl' with no `lock', the patch is needed.
> >  
> 
> The DOM0 is NetBSD_9.x, but it appears to be ok according to what you
> wrote above:
> 
> DOM0# crash
> Crash version 9.3_STABLE, image version 9.3_STABLE.
> Output from a running system is unreliable.
> crash> x/i membar_sync,3
> _membar_sync:   lock addq       $0,fffffffffffffff8 (%rsp)
> _membar_sync+0x7:       ret
> _membar_sync+0x8:       nopl
> crash> 

Yes, I don't think hotpatch is run when running PV

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--