On Tue, 2023-01-17 at 10:09 -0500, Matthew Rosato wrote: > On 1/4/23 7:05 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@xxxxxxxxxxxxx> > > diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c > > index ef38b1514c77..6b0fe8761509 100644 > > --- a/arch/s390/pci/pci.c > > +++ b/arch/s390/pci/pci.c > > @@ -124,7 +124,11 @@ int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas, > > > > WARN_ON_ONCE(iota & 0x3fff); > > fib.pba = base; > > - fib.pal = limit; > > + /* Work around off by one in ISM virt device */ > > + if (zdev->pft == 0x5 && limit > base) > > Nit: maybe a named #define for the ISM pft rather than hard-coding 0x5 here > Hmm, I agree in principle but not sure where to put this #define. Maybe also important to mention that the off-by-one has actually been fixed in current firmware but of course we still have to support broken devices and the workaround still works with fixed ISM.
