Hi Michal,
>>
>> + rc = mpumap_contains_region(xen_mpumap, max_mpu_regions, start, end,
>> &idx);
>> + if ( rc < 0 )
>> + panic("Cannot handle overlapping MPU memory protection regions\n");
> Why panic? This function is not used only at boot time and should propagate
> error to the caller, it's also within a spin lock.
Good point - I will update this to propagate the error in the next version of
the series.
>> + /* This API is only meant to unmap transient regions */
>> + if ( !region_is_transient(&xen_mpumap[idx]) )
> So is this the only purpose of the transient flag? To check that
> unmap_mm_range
> is used on the range that was mapped with map_mm_range? What would happen
> without introducing this flag? You already check for the matching attributes.
>
> ~Michal
>
Yes this is the purpose of the transient flag - we want to ensure that a call
to unmap_mm_range only destroys a mapping that was created by a matching call
to map_mm_range. Due to the fact that map_mm_range may not create a mapping in
the instance that one already exists - `/* Already mapped with same attributes
*/` - we need this check to ensure that unmap_mm_range will not destroy a
pre-existing mapping.
Many thanks,
Hari
