Re: [Xen-devel] [BUG] Xen vm kernel crash in get_free_entries.

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Oct 17, 2013 at 11:04:29PM +0400, Astarta wrote:
> On 10/17/2013 12:55 PM, Astarta wrote:
> >On 10/16/2013 06:17 PM, Pasi Kärkkäinen wrote:
> >>On Wed, Oct 16, 2013 at 02:29:07PM +0100, David Vrabel wrote:
> >>>On 16/10/13 07:28, Astarta wrote:
> >>>>Hello,
> >>>>
> >>>>This is a some kind of a follow up to the
> >>>>http://lists.xen.org/archives/html/xen-devel/2013-09/msg03109.html (
> >>>>Linux 3.11.1 HVM guest kernel crash when started with xl
> >>>>(get_free_entries)).
> >>>>
> >>>>Looks like we've here the similar issue.
> >>>>
> >>>>Xen VM with 3.8.13 kernel crashes in get_free_entries (kernel BUG at
> >>>>drivers/xen/grant-table.c:1181!), i.e in:
> >>>>BUG_ON(grefs_per_grant_frame == 0);. 3.11.5 kernel behaves in exactly
> >>>>the same way.
> >>>>
> >>>>Whole kernel log is attached. It does not contain  any "Grant tables
> >>>>using version" message.
> >>>>
> >>>>Seems that gnttab_request_version() has was never executed, so
> >>>>grefs_per_grant_frame was never set.
> >>>>
> >>>>Could you please advice on this issue?
> >>>I think you're missing the platform pci device required for PVHVM.
> >>>What's your VM's xl.cfg?
> >>>
> >>Yes, exactly, I had "xen_platform_pci=0" in my VM's xl.cfg,
> >>and I assume Astarta has aswell.
> >>
> >>That is because I wanted to test *without* PVHVM, and that is a
> >>valid configuration imho..
> >>(and works OK with xm/xend).
> >>
> >>-- Pasi
> >
> >Thanks for the suggestion, but there is no xl.cfg in /etc/xen/
> >(we're using Citrix XenServer Host 6.2.0-70446c
> > on rhel 6.2), so there is no where to edit xen_platform_pci option.
> >
> >I've attached output from xe vm-list params=all for one of the
> >problem vm. Hope its also ok.
> >
> >Also 3.6 kernel works well with that configuration. I can provide
> >it's boot log if needed.
> >
> >Please suggest.
> >
> >-- 
> >Marina
> 
> 
> will answer by myself. Setting platform:device_id to 1 manually
> helps the 3.11.5 kernel to boot.
> I used xe command for this in the below way.
> xe vm-param-set uuid=<VM UUID> platform:device_id=0001
> 
> The issue that platform:device_id is 0002 for citrix xen by default
> and the latest kernel doesnt boot in this configuration...
> 
> Where do we go from there?
>

Well, it's a Linux kernel bug, I assume, so it should be fixed.
More debugging is needed.

There is, and shouldn't be, a requirement to have Xen platform PCI device 
available..
That's how you enable/disable PVHVM, after all. 

-- Pasi


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