Re: [Xen-devel] [PATCH 07/17] flask: unify {get, set}vcpucontext permissions

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 20/06/16 15:50, Daniel De Graaf wrote:
> On 06/20/2016 10:35 AM, Andrew Cooper wrote:
>> On 20/06/16 15:27, Doug Goldstein wrote:
>>> On 6/20/16 9:04 AM, Daniel De Graaf wrote:
>>>> These permissions were initially split because they were in separate
>>>> domctls, but this split is very unlikely to actually provide security
>>>> benefits: it would require a carefully contrived situation for a
>>>> domain
>>>> to both need access to one type of CPU register and also need to be
>>>> prohibited from accessing another type.
>>>>
>>>> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
>>>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>>> I'm a:
>>>
>>> Reviewed-by: Doug Goldstein <cardoe@xxxxxxxxxx>
>>>
>>> But I'd like to see Andrew Cooper's R-b or comments as well.
>>>
>>
>> I agree.  I can't see a plausible usecase for an entity being entitled
>> to read vcpu content, but not to modify it.
>>
>> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>
> That's not exactly what this patch does: the get and set permissions
> are still split, but unified across the different types of registers.
> Where previously there were 6 permissions, now there are 2.

The boundaries for those hypercalls were somewhat arbitrary, and
definitely awkward to use.  Some information is duplicated between
them.  I plan to make them all disappear, in favour of something more
consistent when altering the migration stream semantics.

~Andrew

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