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

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

The following reply was made to PR kern/57199; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: Brad Spencer <brad%anduin.eldar.org@localhost>
Cc: gnats-bugs%netbsd.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost
Subject: Re: port-xen/57199: Pure PVH i386 guests hang on disk activity
Date: Mon, 15 Jul 2024 21:50:03 +0200

 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
 --