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

[Yi Min Zhao <zyimin@linux.vnet.ibm.com>]

在 2017/9/5 下午5:28, Cornelia Huck 写道:
> On Fri,  1 Sep 2017 06:22:58 +0200
> Yi Min Zhao <zyimin@linux.vnet.ibm.com> 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 <pmorel@linux.vnet.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
>> Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
>> ---
>>   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 = {
>