Re: [PATCH v2 5/5] x86: simplify is_guest_l2_slot()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 24.08.2020 14:50, Andrew Cooper wrote:
> On 24/08/2020 13:35, Jan Beulich wrote:
>> is_pv_32bit_domain() has become expensive, and its use here is
>> redundant: Only 32-bit guests would ever get PGT_pae_xen_l2 set on
>> their L2 page table pages anyway.
>>
>> Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Possibly "if some other error does lead to PGT_pae_xen_l2 ending up
> anywhere else, we still don't want to allow a guest to control the
> entries" ?

I've added this, but I'm not fully convinced it's a meaningful
statement: We only ever invoke the macro for L2 pages, so
"anywhere else" to me meaning more than just L2 pages of 64-bit
guests looks to render the whole thing not very precise.

> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks.

Jan