Re: [Xen-devel] [PATCH V3] x86/altp2m: Hypercall to set altp2m view visibility

[Jan Beulich <jbeulich@xxxxxxxx>]

On 20.02.2020 10:59, Alexandru Stefan ISAILA wrote:
> On 19.02.2020 19:00, Jan Beulich wrote:
>> On 19.02.2020 10:18, Alexandru Stefan ISAILA wrote:
>>> @@ -4835,6 +4836,23 @@ static int do_altp2m_op(
>>>           break;
>>>       }
>>>   
>>> +    case HVMOP_altp2m_set_visibility:
>>> +    {
>>> +        uint16_t altp2m_idx = a.u.set_visibility.altp2m_idx;
>>> +
>>> +        if ( a.u.set_visibility.pad )
>>> +            rc = -EINVAL;
>>> +        else if ( !altp2m_active(d) )
>>> +            rc = -EOPNOTSUPP;
>>> +        else if ( a.u.set_visibility.visible )
>>> +            d->arch.altp2m_working_eptp[altp2m_idx] =
>>> +                d->arch.altp2m_eptp[altp2m_idx];
>>> +        else
>>> +            d->arch.altp2m_working_eptp[altp2m_idx] =
>>> +                mfn_x(INVALID_MFN);
>>
>> Don't you need to bounds check the index before its use?
> 
> Unless we want a index out of bounds from the user. Sorry for not having 
> that, I will add a "altp2m_eptp[array_index_nospec(altp2m_idx, 
> MAX_EPTP)]" in place for the next version.
> 
>> And
>> shouldn't you return an error also for in-range ones which
>> aren't actually valid?
> That is a good thing. Maybe -EINVAL could fit this?

Sure.

Jan

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