Re: [PATCH] xen/pvh: trap access to IO port range 0xcf8-0xcfb

["Roger Pau Monné" <roger.pau@citrix.com>]

El 08/05/15 a les 12.18, Jan Beulich ha escrit:
>>>> On 08.05.15 at 12:00, <roger.pau@citrix.com> wrote:
>> --- a/xen/arch/x86/setup.c
>> +++ b/xen/arch/x86/setup.c
>> @@ -1527,7 +1527,7 @@ static int __hwdom_init io_bitmap_cb(unsigned long s, 
>> unsigned long e,
>>  
>>  void __hwdom_init setup_io_bitmap(struct domain *d)
>>  {
>> -    int rc;
>> +    int rc, i;
> 
> The new variable ought to be of unsigned type and could go
> into the more narrow scope it's needed in.

Why of type unsigned? __set_bit expects an int.

>> @@ -1535,6 +1535,12 @@ void __hwdom_init setup_io_bitmap(struct domain *d)
>>          rc = rangeset_report_ranges(d->arch.ioport_caps, 0, 0x10000,
>>                                      io_bitmap_cb, d);
>>          BUG_ON(rc);
>> +        /*
>> +         * NB: we need to trap accesses to the range 0xcf8-0xcfb in order
>> +         * to intercept 4 byte accesses.
>> +         */
>> +        for ( i = 0xcf8; i < 0xcfc; i++ )
>> +            __set_bit(i, d->arch.hvm_domain.io_bitmap);
> 
> To achieve what the comment says you'd really only need to
> set any one of the four bits.

Indeed, but I think it's more clear this way, the effect is exactly the
same. If you prefer I can only set 0xcf8 and we can get rid of the extra
i variable.

Roger.