Messages in this thread | | | Subject | Re: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions | From | Pierre Morel <> | Date | Fri, 18 Jan 2019 14:29:20 +0100 |
| |
On 17/01/2019 14:02, Robin Murphy wrote: > On 15/01/2019 17:37, Pierre Morel wrote: >> The s390 iommu can only allow DMA transactions between the zPCI device >> entries start_dma and end_dma. >> >> Let's declare the regions before start_dma and after end_dma as >> reserved regions using the appropriate callback in iommu_ops. >> >> The reserved region may later be retrieved from sysfs or from >> the vfio iommu internal interface. > > For this particular case, I think the best solution is to give VFIO the > ability to directly interrogate the domain geometry (which s390 appears > to set correctly already). The idea of reserved regions was really for > 'unexpected' holes inside the usable address space - using them to also > describe places that are entirely outside that address space rather > confuses things IMO. > > Furthermore, even if we *did* end up going down the route of actively > reserving addresses beyond the usable aperture, it doesn't seem sensible > for individual drivers to do it themselves when the core API already > describes the relevant information generically. > > Robin.
Robin,
I already posted a patch retrieving the geometry through VFIO_IOMMU_GET_INFO using a specific capability for the geometry [1], and AFAIU, Alex did not agree with this.
What is different in what you propose?
@Alex: I was hoping that this patch goes in your direction. What do you think?
Thanks, Pierre
[1]: https://lore.kernel.org/patchwork/patch/1030369/
> >> >> This seems to me related with the work Shameer has started on >> vfio_iommu_type1 so I add Alex and Shameer to the CC list. >> >> >> Pierre Morel (1): >> iommu/s390: Declare s390 iommu reserved regions >> >> drivers/iommu/s390-iommu.c | 29 +++++++++++++++++++++++++++++ >> 1 file changed, 29 insertions(+) >> >
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
| |