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

[Matthew Rosato <mjrosato@linux.ibm.com>]

On 12/10/24 3:58 AM, David Hildenbrand wrote:

> Maybe there is a reason s390x needs to handle this using memory_region_notify_iommu() callbacks instead of doing it similar to "struct vfio_memory_listener" when registered on &address_space_memory without a viommu.
> 

Hi David,

I think I sorted a way to handle this such that, when direct mapping, we use a memory region alias instead so that vfio can ultimately handle all of the pinning/unpinning in the non-iommu path of vfio_listener_region_add/del, just like it does for other platforms.  But for s390 the alias is needed to provide the SDMA offset so as to ensure that e.g. GPA X maps to iova SDMA+X.  Looks to be working nicely so far with my rework of the associated kernel series -- Going to send as part of v2, would appreciate it if you'd give that a look.

Thanks,
Matt