Re: [PATCH] vfio: Request THP-aligned mmap for device fds

[Ryan Roberts]

On 18/06/2026 15:55, Lorenzo Stoakes wrote:
> +cc Ryan for contPMD
> 
>>
>>> And maybe there's a CONTPMD architecture we should also consider?
>>
>> ARM HW supports "CONTPMD" but I suppose it is not implemented..
> 
> Maybe Ryan has thoughts?

Sorry not quite sure what you're asking so will give a generic answer:

Arm arch does indeed support CONTPMD at level 2 in the same way that it supports
CONTPTE at level 3, as follows:

+-----------+-----------+-----------+-----------+-----------+
| Page Size |  CONTPTE  |    PMD    |  CONTPMD  |    PUD    |
+-----------+-----------+-----------+-----------+-----------+
|    4KB    |   64KB    |    2MB    |    32MB   |    1GB    |
|   16KB    |    2MB    |   32MB    |     1GB   |           |
|   64KB    |    2MB    |  512MB    |    16GB   |           |
+-----------+-----------+-----------+-----------+-----------+

For HugeTLB, Linux/arm64 support all of the listed sizes today. For !HugeTLB
(i.e. THP, large file filos) Linux/arm64 supports CONTPTE and PMD only. We could
(and probably would) extend to support CONTPMD once THP PUDs are supported.

Not sure if that answers the question?

Thanks,
Ryan

> 
>>
>> Jason
> 
> Thanks, Lorenzo