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

[David Vrabel <david.vrabel@citrix.com>]

On 17/10/13 20:28, Pasi Kärkkäinen wrote:
> 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.

I suspect some of the changes for ARM has caused this (because ARM is
sort of PVHVM without a platform PCI device) but I had a quick look and
couldn't spot anything.  Stefano, any ideas?

David