Re: [RFC][PATCH 3/5] tools:libxc: remove mmio BAR out of RMRR mappings

["Chen, Tiejun" <tiejun.chen@intel.com>]

On 2014/8/8 23:49, Jan Beulich wrote:
>>>> On 07.08.14 at 13:02, <tiejun.chen@intel.com> wrote:
>> @@ -300,6 +302,30 @@ static int setup_guest(xc_interface *xch,
>>           goto error_out;
>>       }
>>
>> +    /* We need to move mmio range out of RMRR mapping. */
>> +    rc = xc_get_rmrr_map(xch, map, E820MAX);
>> +    if (rc < 0)
>> +    {
>> +        PERROR("Could not get RMRR info on domain");
>> +    }
>> +    else if ( rc )
>> +    {
>> +        for ( i = 0; i < rc; i++ )
>> +        {
>> +            rmrr_end = map[i].addr + map[i].size + 1;
>> +            if ( rmrr_end > mmio_start )
>> +            {
>> +                mmio_start = rmrr_end;
>> +            }
>> +        }
>
> This seems way too simplistic - what if the RMRRs are referring to
> memory regions extremely far apart?
>
>> +        mmio_size = (1ull << 32) - mmio_start;
>
> Limiting things to 4Gb?
>
>> +        if ( mmio_size <= 0 )
>
> mmio_size is an unsigned quantity, so this won't do what you intend.

Yes, you're right.

With a further consideration, mmio size should be configured so I think 
it may be enough just to check if current mmio is overlapping, then let 
user determine what next should do.

Please comments this in next revision directly.

Thanks
Tiejun
>
> Jan
>
>