Re: [Xen-devel] [PATCH v7 02/10] arch/arm: add consistency check to REMOVE p2m changes

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 05/06/2014 05:51 PM, Julien Grall wrote:
> Hi Arianna,
> 
> On 05/05/2014 04:54 PM, Arianna Avanzini wrote:
>> Currently, the REMOVE case of the switch in apply_p2m_changes()
>> does not perform any consistency check on the mapping to be removed.
>> More in detail, the code does not check if the guest address to be
>> unmapped is actually mapped to the machine address given as a
>> parameter.
>> This commit attempts to add the above-described consistency check
>> to the REMOVE path of apply_p2m_changes(). This is instrumental to
>> one of the following commits which implements the possibility to
>> trigger the removal of p2m ranges via the memory_mapping DOMCTL
>> for ARM.
>>
>> Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
>> Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>> Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
>> Cc: Paolo Valente <paolo.valente@xxxxxxxxxx>
>> Cc: Julien Grall <julien.grall@xxxxxxxxxx>
>> Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
>> Cc: Jan Beulich <JBeulich@xxxxxxxx>
>> Cc: Keir Fraser <keir@xxxxxxx>
>> Cc: Tim Deegan <tim@xxxxxxx>
>> Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
>> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> Cc: Eric Trudeau <etrudeau@xxxxxxxxxxxx>
>> Cc: Viktor Kleinik <viktor.kleinik@xxxxxxxxxxxxxxx>
>>
>> ---
>>
>>     v7:
>>         - Silently ignore the fact that, when removing a mapping, the 
>> specified
>>           gfn is not mapped at all.
> 
> I think you misunderstood my previous comment. I didn't ask to remove
> "maddr += ...". This code was right. Now the failure (i.e the MFN
> doesn't match the GFN) is obscure.
> 
> On x86, Xen will continue to unmap even if we fail to remove one entry.
> Of course, it will return an error at the end.

I forgot to add: it would be nice to have some print message as x86 does.

-- 
Julien Grall

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