Re: [ANNOUNCE][RFC] KVMGT - the implementation of Intel GVT-g(full GPU virtualization) for KVM

From: Jike Song
Date: Fri Dec 05 2014 - 23:20:33 EST

On 12/05/2014 04:50 PM, Gerd Hoffmann wrote:
A few comments on the kernel stuff (brief look so far, also
compile-tested only, intel gfx on my test machine is too old).

* Noticed the kernel bits don't even compile when configured as
module. Everything (vgt, i915, kvm) must be compiled into the

Yes, that's planned to be done along with separating hypervisor-related
code from vgt.

* Design approach still seems to be i915 on vgt not the other way

So far yes.

Qemu/SeaBIOS bits:

I've seen the host bridge changes identity from i440fx to
copy-pci-ids-from-host. Guess the reason for this is that seabios uses
this device to figure whenever it is running on i440fx or q35. Correct?

I did some trick in seabios/qemu. The purpose is to make qemu:

- provide IDs of an old host bridge to SeaBIOS
- provide IDs of new host bridge(the physical ones) to guest OS

So I made seabios to tell qemu that POST is done before jumping to guest
OS context.

This may be the simplest method to make things work, but yes, q35 emulation
of qemu may have this unnecessary, see below.

What are the exact requirements for the device? Must it match the host
exactly, to not confuse the guest intel graphics driver? Or would
something more recent -- such as the q35 emulation qemu has -- be good
enough to make things work (assuming we add support for the
graphic-related pci config space registers there)?

I don't know that is exactly needed, we also need to have Windows
driver considered. However, I'm quite confident that, if things gonna
work for IGD passthrough, it gonna work for GVT-g.

The patch also adds a dummy isa bridge at 0x1f. Simliar question here:
What exactly is needed here? Would things work if we simply use the q35
lpc device here?


more to come after I've read the paper linked above ...

Thanks for review :)


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at