Re: [PATCH v2 1/2] s390x/pci: add support for guests that request direct mapping

[Matthew Rosato]

On 12/16/24 12:29 PM, David Hildenbrand wrote:
> On 16.12.24 18:26, Matthew Rosato wrote:
>>
>>>> Good point.  Using s390_get_memory_limit() sounds good to me; That will 
>>>> make v3 of this series dependent on the s390x virtio-mem series but sounds 
>>>> like you're sending that sometime this week anyway.
>>>
>>> If my testing is good and there are no further comments, I'll queue it 
>>> directly (no change to v2) to send it upstream.
>>>
>>> So it's probably a good idea to wait with a new series her.
>>>
>>
>> OK
>>
>>>
>>> We discussed at some point maybe requiring disabling uncoordinated 
>>> discarding of RAM (virtio-balloon), is that already done implicitly now?
>>>
>>
>> Yes, this should be handled via the call to 
>> ram_block_uncoordinated_discard_disable() in 
>> vfio_ram_block_discard_disable() - I just traced that now to double-check.
>>
> 
> Cool, can you briefly mention that in the patch description? Thanks!
> 

Sure, I'll add something like

Pinning for the direct mapping case is handled via vfio and its memory
listener.  Additionally, ram discard settings are inherited from vfio:
coordinated discards (e.g. virtio-mem) are allowed while uncoordinated
discards (e.g. virtio-balloon) are disabled.