Re: [Xen-devel] [PATCH v2 29/30] xen/x86: allow PVHv2 to perform foreign memory mappings

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 10/10/16 15:21, Jan Beulich wrote:
>>>> On 27.09.16 at 17:57, <roger.pau@xxxxxxxxxx> wrote:
>> --- a/xen/arch/x86/mm/p2m.c
>> +++ b/xen/arch/x86/mm/p2m.c
>> @@ -2793,7 +2793,7 @@ int p2m_add_foreign(struct domain *tdom, unsigned long 
>> fgfn,
>>      struct domain *fdom;
>>  
>>      ASSERT(tdom);
>> -    if ( foreigndom == DOMID_SELF || !is_pvh_domain(tdom) )
>> +    if ( foreigndom == DOMID_SELF || !has_hvm_container_domain(tdom) )
>>          return -EINVAL;
> 
> Can PV domains make it here? If not, dropping the predicate would
> seem the better adjustment.

Is there any chance that in the future PV domains might accidentally get
here because of some other changes in the future?  If so, leaving the
predicate seems like a sensible precaution to reduce the risk of XSAs
down the road, since we're doing a load of checking already anyway. ;-)

At the moment, nobody's going to get past he "is_hardware_domain()"
except dom0, but presumably that will change once we get driver domains
implemented.

 -George

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