Re: [Xen-devel] [PATCH v5 2/3] xen: add the RTC io space to the blocked access list

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.05.15 at 13:55, <roger.pau@xxxxxxxxxx> wrote:
> El 08/05/15 a les 13.50, Jan Beulich ha escrit:
>>>>> On 07.05.15 at 16:54, <roger.pau@xxxxxxxxxx> wrote:
>>> @@ -1548,6 +1549,8 @@ int __init construct_dom0(
>>>          rc |= ioports_deny_access(d, pmtmr_ioport, pmtmr_ioport + 3);
>>>      /* PCI configuration space (NB. 0xcf8 has special treatment). */
>>>      rc |= ioports_deny_access(d, 0xcfc, 0xcff);
>>> +    /* Never permit direct access to the RTC/CMOS registers. */
>>> +    rc |= ioports_deny_access(d, RTC_PORT(0), RTC_PORT(1));
>> 
>> Looks like I prematurely committed this: Did you test that Dom0
>> still can access CMOS/RTC with that change? I ask because the
>> ioports_access_permitted() checks in guest_io_{read,write}()
>> now ought to fail for Dom0... (Apart from that on second thought
>> it looks wrong also conceptionally - we don't want to deny Dom0
>> access to these ports, we just don't want it to access them
>> directly.)
> 
> Yes, it looks like this needs to be reverted. I think we need to do
> something similar to what I've done with 0xcf8; don't add the ports to
> ioports_deny_access and just trap them for PVH in setup_io_bitmap.

Right. Hence I'll ditch that v2 patch, awaiting a v3 doing both.

Jan


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