Re: [Xen-devel] [v7][RFC][PATCH 06/13] hvmloader/ram: check if guest memory is out of reserved device memory maps

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.11.14 at 12:32, <tiejun.chen@xxxxxxxxx> wrote:
> On 2014/11/17 19:17, Jan Beulich wrote:
>>>>> On 17.11.14 at 12:08, <tiejun.chen@xxxxxxxxx> wrote:
>>
>>> On 2014/11/17 18:05, Jan Beulich wrote:
>>>>>>> On 17.11.14 at 08:57, <tiejun.chen@xxxxxxxxx> wrote:
>>>>> --- a/xen/common/memory.c
>>>>> +++ b/xen/common/memory.c
>>>>> @@ -698,10 +698,13 @@ struct get_reserved_device_memory {
>>>>>         unsigned int used_entries;
>>>>>     };
>>>>>
>>>>> -static int get_reserved_device_memory(xen_pfn_t start,
>>>>> -                                      xen_ulong_t nr, void *ctxt)
>>>>> +static int get_reserved_device_memory(xen_pfn_t start, xen_ulong_t nr, 
>>>>> u16
>>> seg,
>>>>> +                                      u16 *ids, int cnt, void *ctxt)
>>>>
>>>> While the approach is a lot better than what you did previously, I still
>>>> don't like you adding 3 new parameters when one would do (calling
>>>> the callback for each SBDF individually): That way you avoid
>>>
>>> Do you mean I should do this?
>>>
>>> for_each_rmrr_device ( rmrr, bdf, i )
>>> {
>>>      sbdf = PCI_SBDF(seg, rmrr->scope.devices[i]);
>>>            rc = func(PFN_DOWN(rmrr->base_address),
>>>                      PFN_UP(rmrr->end_address) -
>>> PFN_DOWN(rmrr->base_address),
>>>                sbdf,        
>>>                      ctxt);
>>>
>>> But each different sbdf may occupy one same rmrr entry as I said
>>> previously, so we have to introduce more codes to filter them as one
>>> identified entry in the callback.
>>
>> Not really - remember that part of what needs to be done is to make
>> sure all devices associated with a given RMRR get assigned to the
>> same guest? Or the callback function could use a special return value
> 
> Yes, but I means in the callback,
> 
> get_reserved_device_memory()
> {
>       ...
>       for(each assigned pci devs:pt_sbdf)
>               if (sbdf == pt_sbdf)
>                       __copy_to_guest_offset(buffer, ...)
> 
> Buffer may be copied to include multiple same entries if we have two or 
> more assigned devices associated to one give RMRR entry.

Which would be easily avoided by ...

>> (e.g. 1) to signal that the iteration for the current RMRR can be
>> terminated (or further entries skipped).

... the approach I outlined.

Jan


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