Re: [PATCH v7 12/14] VT-d: replace all-contiguous page tables by superpage mappings

["Durrant, Paul" <xadimgnik@xxxxxxxxx>]

On 05/07/2022 13:48, Jan Beulich wrote:
> When a page table ends up with all contiguous entries (including all
> identical attributes), it can be replaced by a superpage entry at the
> next higher level. The page table itself can then be scheduled for
> freeing.
>
> The adjustment to LEVEL_MASK is merely to avoid leaving a latent trap
> for whenever we (and obviously hardware) start supporting 512G mappings.
>
> Note that cache sync-ing is likely more strict than necessary. This is
> both to be on the safe side as well as to maintain the pattern of all
> updates of (potentially) live tables being accompanied by a flush (if so
> needed).
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Paul Durrant <paul@xxxxxxx>