Which Hypervisors allow Raw PCI access?

Question

I am trying to find out which Hypervisor will allow me to grant access to specialized PCI cards (such as a telephony card) to a virtual machine. So far I have tried out VMWare ESXi server and it doesn't seem to allow me to do this. I have heard that Microsoft Virtual Server does allow this, but I haven't been able to find any supporting documentation.

Answer 1

I'd look into Xen, it appears that you can load a backend xen driver on the host OS which will then allow you to communicate directly with the hardware from the guest.

See this link for more information. I'm not a Xen user, but from my virtualization experience I would guess that the paravirtualization aspects of a Xen host/guess is going to be your best bet for raw device access.

Answer 2

Yes, Xen can do this successfully. It is called PCI Passthrough: http://wiki.xen.org/wiki/Xen_PCI_Passthrough

I've done this successfully for both Windows and Linux guests with Xen 4.x, using my system's IOMMU. There are some restrictions on which devices can be assigned to which guests based on the PCI hierarchy in your particular system. You can view yours in Linux using 'lspci -t' (for "tree").

The IOMMU is located fairly high up in the tree, so on laptop-like systems, there may not be much partitioning available. Add-in PCIe cards can almost always be assigned, though.