Re: [Qemu-devel] [PATCH v2 3/3] s390x/pci: add iommu replay callback

[Yi Min Zhao]

在 2017/9/5 下午5:28, Cornelia Huck 写道:
> On Fri,  1 Sep 2017 06:22:58 +0200
> Yi Min Zhao <address@hidden> wrote:
>
> > Let's introduce iommu replay callback for s390 pci iommu memory region.
> > Currently we don't need any dma mapping replay. So let it return
> > directly. This implementation will avoid meaningless loops calling
> > translation callback.
> >
> > Reviewed-by: Pierre Morel <address@hidden>
> > Reviewed-by: Halil Pasic <address@hidden>
> > Signed-off-by: Yi Min Zhao <address@hidden>
> > ---
> >   hw/s390x/s390-pci-bus.c | 11 +++++++++++
> >   1 file changed, 11 insertions(+)
> >
> > diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
> > index bd8a3e1e1c..69f45e3715 100644
> > --- a/hw/s390x/s390-pci-bus.c
> > +++ b/hw/s390x/s390-pci-bus.c
> > @@ -397,6 +397,16 @@ static IOMMUTLBEntry 
> > s390_translate_iommu(IOMMUMemoryRegion *mr, hwaddr addr,
> >       return ret;
> >   }
> >   
> > +static void s390_pci_iommu_replay(IOMMUMemoryRegion *iommu,
> > +                                  IOMMUNotifier *notifier)
> > +{
> > +    /* It's impossible to plug a pci device on s390x that already has iommu
> > +     * mappings which need to be replayed, that is due to the "one iommu per
> > +     * zpci device" construct. So we don't need iommu replay currently.
> I must say that 'currently' still throws me off. Does this refer to
> vfio? If yes, reword to something like 'Should we support migration of
> vfio-pci devices in the future, we need to revisit this.'?
Yeah, it refers to vfio especially. I update this in next version.
> > +     */
> > +    return;
> > +}
> > +
> >   static S390PCIIOMMU *s390_pci_get_iommu(S390pciState *s, PCIBus *bus,
> >                                           int devfn)
> >   {
> > @@ -1045,6 +1055,7 @@ static void 
> > s390_iommu_memory_region_class_init(ObjectClass *klass, void *data)
> >       IOMMUMemoryRegionClass *imrc = IOMMU_MEMORY_REGION_CLASS(klass);
> >   
> >       imrc->translate = s390_translate_iommu;
> > +    imrc->replay = s390_pci_iommu_replay;
> >   }
> >   
> >   static const TypeInfo s390_iommu_memory_region_info = {