Is it reasonable to do error injection with "CONFIG_IOMMU_API" ?

That means if use default config(CONFIG_IOMMU_API = n),  we can not do 
error injection to pci devices?

Well we can't pass them through either so ...

In any case, this is not a priority. First we need to implement a solid
error injection facility for the *host*. The guest one is really really
low on the list.

Cheers,
Ben.