Re: [Xen-devel] Xen-unstable-staging: Xen BUG at iommu_map.c:455

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.04.15 at 20:50, <linux@xxxxxxxxxxxxxx> wrote:
> Monday, April 20, 2015, 6:11:42 PM, you wrote:
>>>>> On 16.04.15 at 11:28, <tim@xxxxxxx> wrote:
>>> At 22:35 +0100 on 11 Apr (1428791713), Andrew Cooper wrote:
>>>> At least we now understand why it happens.  I will defer to others CC'd
>>>> on this thread for their opinions in the matter.
>>> 
>>> The patch semes like a pretty good check to me, though I'm not
>>> convinced it's race-free.  At the least I'd cache the m2p lookup so we
>>> use the same value for the checks and the map_page() call. 
>>> 
>>> And IMO update_paging_mode() ought to log and reject bogus GFNs as
>>> well.
> 
>> could you give the patch below a try, namely also in the context
>> of seeing again the issue originally fixed by Andrew's initial patch?
>> Please make sure you try a debug build and you have
>> "iommu=debug" on the Xen command line.
> 
> I'm running with it now, have seen no issues so far !

Interesting - didn't you say that as a side effect of Andrew's patch
you saw massive log spam?

Jan


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