Re: [PATCH v1 4/5] vpci: use separate rangeset for BAR unmapping

[Jan Beulich <jbeulich@suse.com>]

On 31.05.2025 14:54, Stewart Hildebrand wrote:
> Introduce a new per-BAR rangeset, unmap_mem, for p2m unmapping. Rename
> existing mem rangeset to map_mem, which is now only used for mapping.
> Populate unmap_mem by moving just-mapped ranges from map_mem to
> unmap_mem. In modify_bars(), skip recalculating the ranges when
> unmapping as they are already stored in unmap_mem.
> 
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com>

Already when per-BAR rangsets were introduced I questioned that, resource
efficiency wise: A BAR fundamentally is a single range. For e.g. the MSI-X
table we punch a hole, but it then is still questionable if representing
the result as a rangeset is appropriate. Now you further extend the waste.
Since unmapping something that was never mapped should not be a problem,
does what needs unmapping really need representing as a rangeset, rather
than as a plain range?

Jan