On Dec 4, 2014 5:27 AM, "Jike Song" <jike.song@xxxxxxxxx> wrote:
>
> Hi all,
Hi,
>
> We are pleased to announce the first release of KVMGT project. KVMGT is the implementation of Intel GVT-g technology, a full GPU virtualization solution. Under Intel GVT-g, a virtual GPU instance is maintained for each VM, with part of performance critical resources directly assigned. The capability of running native graphics driver inside a VM, without hypervisor intervention in performance critical paths, achieves a good balance of performance, feature, and sharing capability.
Sounds great.
>
>
> KVMGT is still in the early stage:
>
> - Basic functions of full GPU virtualization works, guest can see a full-featured vGPU.
> We ran several 3D workloads such as lightsmark, nexuiz, urbanterror and warsow.
>
> - Only Linux guest supported so far, and PPGTT must be disabled in guest through a
> kernel parameter(see README.kvmgt in QEMU).
>
> - This drop also includes some Xen specific changes, which will be cleaned up later.
>
> - Our end goal is to upstream both XenGT and KVMGT, which shares ~90% logic for vGPU
> device model (will be part of i915 driver), with only difference in hypervisor
> specific services
>
> - insufficient test coverage, so please bear with stability issues :)
>
>
>
> There are things need to be improved, esp. the KVM interfacing part:
>
> 1 a domid was added to each KVMGT guest
>
> An ID is needed for foreground OS switching, e.g.
>
> # echo <domid> > /sys/kernel/vgt/control/foreground_vm
>
> domid 0 is reserved for host OS.
>
>
> 2 SRCU workarounds.
>
> Some KVM functions, such as:
>
> kvm_io_bus_register_dev
> install_new_memslots
>
> must be called *without* &kvm->srcu read-locked. Otherwise it hangs.
>
> In KVMGT, we need to register an iodev only *after* BAR registers are
> written by guest. That means, we already have &kvm->srcu hold -
> trapping/emulating PIO(BAR registers) makes us in such a condition.
> That will make kvm_io_bus_register_dev hangs.
>
> Currently we have to disable rcu_assign_pointer() in such functions.
>
> These were dirty workarounds, your suggestions are high welcome!
>
>
> 3 syscalls were called to access "/dev/mem" from kernel
>
> An in-kernel memslot was added for aperture, but using syscalls like
> open and mmap to open and access the character device "/dev/mem",
> for pass-through.
>
>
>
> The source codes(kernel, qemu as well as seabios) are available at github:
>
> git://github.com/01org/KVMGT-kernel
> git://github.com/01org/KVMGT-qemu
> git://github.com/01org/KVMGT-seabios
>
> In the KVMGT-qemu repository, there is a "README.kvmgt" to be referred.
>
>
>
> More information about Intel GVT-g and KVMGT can be found at:
>
> https://www.usenix.org/conference/atc14/technical-sessions/presentation/tian
> http://events.linuxfoundation.org/sites/events/files/slides/KVMGT-a%20Full%20GPU%20Virtualization%20Solution_1.pdf
>
>
> Appreciate your comments, BUG reports, and contributions!
I'll prepare fedora builds for testing. Users would do 2 commands to use KVMGT. Feel free to CC me about changes and for testing. I have some devices with Intel graphics. I'll test.
>
>
>
>
> --
> Thanks,
> Jike
--
-Igor Gnatenko
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