Re: Dom0 linux 4.0 + devel/for-linus-4.1 branch: p2m.c:884:d0v0 gfn_to_mfn failed! gfn=ffffffff001ed type:4

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

On 13/04/15 16:11, Sander Eikelenboom wrote:
> 
> Monday, April 13, 2015, 2:21:21 PM, you wrote:
> 
>> On 13/04/15 13:14, Sander Eikelenboom wrote:
>>>
>>> Monday, April 13, 2015, 2:07:02 PM, you wrote:
>>>
>>>> On 13/04/15 12:21, Sander Eikelenboom wrote:
>>>>>
>>>>> Monday, April 13, 2015, 11:50:51 AM, you wrote:
>>>>>
>>>>>> On 13/04/15 10:39, Sander Eikelenboom wrote:
>>>>>>> Hi David,
>>>>>>>
>>>>>>> I seem to have spotted some trouble with a 4.0 dom0 kernel with the 
>>>>>>> devel/for-linus-4.1 branch pulled on top.
>>>>>>>
>>>>>>> Does this remind you of any specific commits in the devel/for-linus-4.1 branch that could
>>>>>>> likely be involved that i could try to revert ?
>>>>>
>>>>>> Yes.  This will probably be 4e8c0c8c4bf3a (xen/privcmd: improve
>>>>>> performance of MMAPBATCH_V2) which makes the kernel try harder to map
>>>>>> all GFNs instead of failing on the first one.
>>>>>
>>>>>> I think this is qemu incorrectly trying to map GFNs.
>>>>>
>>>>>> David
>>>>>
>>>>> Reverted that specific one, but still get those messages.
>>>
>>>> You'll have to bisect it then.  Because I don't see any other relevant
>>>> commits in devel/for-linus-4.1
>>>
>>>> David
>>>
>>> Ok .. hmm first candidate of the bisect also looks interessting:
>>> [628c28eefd6f2cef03b212081b466ae43fd093a3] xen: unify foreign GFN map/unmap for auto-xlated physmap guests
> 
>> Unless your dom0 is PVH, no.
> 
>> David
> 
> Bisection came back with:
> 
> 22d8a8938407cb1342af763e937fdf9ee8daf24a is the first bad commit
> commit 22d8a8938407cb1342af763e937fdf9ee8daf24a
> Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Date:   Fri Apr 3 10:28:08 2015 -0400
> 
>     xen/pciback: Don't disable PCI_COMMAND on PCI device reset.

I don't really understand how this could cause the symptoms you reported.

I don't have time to look into this myself so I'm going to drop these
two pciback patches for now.

David