Re: [PATCH v6 4/6] s390/pci: Use dma-iommu layer

Niklas Schnelle
2023-02-17T08:52:24Z

On Wed, 2023-02-15 at 13:00 -0500, Matthew Rosato wrote:
> On 2/15/23 7:03 AM, Niklas Schnelle wrote:
> > While s390 already has a standard IOMMU driver and previous changes have
> > added I/O TLB flushing operations this driver is currently only used for
> > user-space PCI access such as vfio-pci. For the DMA API s390 instead
> > utilizes its own implementation in arch/s390/pci/pci_dma.c which drives
> > the same hardware and shares some code but requires a complex and
> > fragile hand over between DMA API and IOMMU API use of a device and
> > despite code sharing still leads to significant duplication and
> > maintenance effort. Let's utilize the common code DMAP API
> > implementation from drivers/iommu/dma-iommu.c instead allowing us to
> > get rid of arch/s390/pci/pci_dma.c.
> >
> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> > ---
>
> FYI, this patch doesn't fit on top of iommu-next, I'd guess at least due to baolu's 'Retire detach_dev callback' series, which removed .detach_dev and added .set_platform_dma_ops for s390-iommu. That's relevant here, because now that this patch enables dma-iommu for s390 and removes the platform DMA ops it must now remove .set_platform_dma_ops/s390_iommu_set_platform_dma for s390-iommu.
>
> Matt

Ok, yes this series is currently against v6.2-rc8. Should I rebase
against iommu-next and send a v7 before further review or after?

Thanks,
Niklas