Re: [Xen-devel] [RFC PATCH 2/9] iommu: Add ability to map/unmap the number of pages

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

Hi Jan

On Wed, Mar 22, 2017 at 5:44 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 15.03.17 at 21:05, <olekstysh@xxxxxxxxx> wrote:
>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
>>
>> Extend the IOMMU code with new APIs and platform callbacks.
>> These new map_pages/unmap_pages API do almost the same thing
>> as existing map_page/unmap_page ones except the formers can
>> handle the number of pages. So do new platform callbacks.
>>
>> Currently, this patch requires to modify neither
>> existing IOMMU drivers nor P2M code.
>> But, the patch might be rewritten to replace existing
>> single-page stuff with the multi-page one followed by modifications
>> of all related parts.
>
> Yes please. However, unless you strictly need a page count, please
> instead use an "order" parameter. Doing that has been on my todo
> list for quite a while.
>
> Jan
>

The patch introduces new iommu_map_pages/iommu_unmap_pages APIs as well
as new map_pages/unmap_pages platform callbacks.

So, we just need to replace single-page APIs with multi-page ones, but
leave both "new" (map_pages/unmap_pages) and "old"
(map_page/unmap_page) platform callbacks.
This way doesn't require to modify existing IOMMU drivers right now,
just P2M code. Or we need to replace platform callbacks too?

Don't mind to use order instead of page count.

-- 
Regards,

Oleksandr Tyshchenko

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