Re: [PATCH] x86/xsave: Remove xfeat_mask checking from validate_xstate()

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 02/06/14 07:43, Jan Beulich wrote:
>>>> On 30.05.14 at 13:57, <andrew.cooper3@citrix.com> wrote:
>> What further sanity checking would be wanted/needed?
>>
>> The sending Xen must have gotten this correct else it wouldn't have an 
>> xsave area to send in the first place.  If the receiving the Xen found 
>> parts it didn't like, the local validity checks would fail.
>>
>> As far as I can see, the only case this might do something unexpected is 
>> if the individual xfeature_mask got changed on transit, at which point 
>> the receiving Xen would fail the xsave load, despite the xsave area 
>> being valid for the current cpu.
> Whether the loading would fail really depends on what exactly became
> corrupted.

The current behaviour is that the load would fail, as validate_xstate()
would fail.

>
> But in the end the question is - are you intending to no longer
> communicate this bit of information in the v2 migration stream?
>
> Jan
>

Ideally I would like to cease communicating this in the v2 stream.

~Andrew