Re: [Xen-devel] linux PVH broken in 3.16.0-rc7 (arch_gnttab_map_shared)

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Aug 06, 2014 at 02:23:25PM -0700, Mukesh Rathor wrote:
> On Tue, 5 Aug 2014 12:00:12 +0100
> David Vrabel <david.vrabel@xxxxxxxxxx> 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@xxxxxxxxxx>
> > > 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.

If you revert David's patch (x86/xen: safely map and unmap ..) does it
continue booting without the issue below?

Thanks!
> 
> [    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
> 
> 
> 
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