Re: linux PVH broken in 3.16.0-rc7 (arch_gnttab_map_shared)

[Mukesh Rathor <mukesh.rathor@oracle.com>]

On Tue, 5 Aug 2014 12:00:12 +0100
David Vrabel <david.vrabel@citrix.com> wrote:

> On 02/08/14 00:46, Mukesh Rathor wrote:
> > Hi,
> > 
> > Not sure if this already got reported, but it appears 
> > 
> > commit b7dd0e3
> > Author: David Vrabel <david.vrabel@citrix.com>
> > Date:   Fri Jul 11 16:42:34 2014 +0100
> > 
> >     x86/xen: safely map and unmap grant frames when in atomic
> > context
> > 
> > has broken boot of domU PVH. The reason being arch_gnttab_map_shared
> > is getting called before gnttab_shared_vm_area gets initialized by
> > arch_gnttab_init(). As the comment says,
> > 
> > --->
> > /* Call it _before_ __gnttab_init as we need to initialize the
> >  *  * xen_auto_xlat_grant_frames first. */
> > core_initcall(xen_pvh_gnttab_setup);
> > <---
> > 
> > we can't wait till arch_gnttab_init is called by __gnttab_init().
> 
> Does this fix it?  I can't test it because the only box I have easily
> available for testing is AMD.
> 
> David
> 

Well, I don't see the crash, but guest hangs. My hunch is the pte
entries that are populated are not correct, but I don't have time to
look into it right now, so I'll let you debug.

[    1.905278] systemd[1]: Started dracut pre-udev hook.
[    1.905870] systemd[1]: Starting udev Kernel Device Manager...
[    1.945204] systemd-udevd[275]: starting version 204
[    2.625252] systemd-sysctl (526) used greatest stack depth: 13192 bytes left
[   49.832064] random: nonblocking pool is initialized
.. hang.. 

thanks
mukesh