memory overcomittment with sr-iov device assighment

[alex.nlnnfn@xxxxxxxxx]

Hello list,

I looked into Xen documentation and also Xen wiki and I could't find a 
definitive answer if Xen supports memory over-commitment when VMs use SR-IOV 
device assignment (passthrough). Memory over-commitment I mean giving VMs more 
RAM than is available in the host.

I know that ESX doesn't support it, and also QEMU/KVM pins all RAM when a 
device is directly assigned to a VM (VFIO_IOMMU_MAP_DMA ioctl). I have two 
questions:

1. Does Xen supports memory over commitment when all VMs are using direct 
device assignment e.g., SR-IOV?
2. Would you please point me to the code that does the pinning?

Thanks,
Alex