libvirt users - Oct 2014 - Re: Virtual gaming/workstation desktops using KVM VGA passthrough?

Dear List,

Recently I read an article [1] about how to use KVM and VGA passthrough to
create multiple GPU accelerated VM's for use in gaming or as virtual
workstations:

[1]
http://www.pugetsystems.com/labs/articles/Multiheaded-NVIDIA-Gaming-using-Ubuntu-14-04-KVM-585/

I'm planning on building a KVM workstation to do this using CentOS 7 or
Ubuntu 14.04 LTS as the base virtualization host and then an Intel Xeon CPU
and two Nvidia GeForce GTX 750's as GPU's for the virtual machines.

I'm really new to this sort of GPU passthrough on KVM and am wondering if
anyone has any advice or has done this before?

Thank you!

Hi Alex,

The first bit of advice that I was about to give was that you should
have a look at a particular thread on the Arch Linux user forum.  But
as it turns out, the article that you found (which seems really
well-written) already mentions that thread, and in fact even links to
one of my comments on that thread, namely this comment:
https://bbs.archlinux.org/viewtopic.php?pid=1313007#p1313007

With regard to CentOS 7 vs Ubuntu 14.04, keep in mind that VFIO (which
is part of the Linux kernel) is relatively new and is still rapidly
evolving.

I'm not very familiar with CentOS, but if I'm not mistaken, CentOS 7
uses kernel 3.10 by default.  You'll probably want to use a newer
kernel version, which would have better VFIO support.  Again, I'm not
really familiar with CentOS, but my understanding is that many feel
that updating the kernel in CentOS isn't a good idea. So with this in
mind, you might be better off using a distro that ships with a newer
kernel version, such as Fedora or Ubuntu, etc.

In my experience, Ubuntu 14.04, which ships with kernel 3.13 and QEMU
2.0, works pretty well with VFIO.  However, Ubuntu 14.10, which will
ship with kernel 3.16 and QEMU 2.1, seems to work a little better, but
is still pre-release and so has a few other bugs.  If you go with
Ubuntu 14.04, you might want to install a newer "mainline" kernel.
But in any case, please do keep in mind that VFIO is still new and so
you will almost assuredly encounter some bugs.  So don't expect 100%
stability.

Hope the above is of some help.

Regards,
GizmoChicken

On Fri, Oct 3, 2014 at 5:19 PM, Alex G.S. <alxgrtnstrngl@gmail.com>
wrote:
> Dear List,
>
> Recently I read an article [1] about how to use KVM and VGA passthrough to
> create multiple GPU accelerated VM's for use in gaming or as virtual
> workstations:
>
> [1]
>
http://www.pugetsystems.com/labs/articles/Multiheaded-NVIDIA-Gaming-using-Ubuntu-14-04-KVM-585/
>
> I'm planning on building a KVM workstation to do this using CentOS 7 or
> Ubuntu 14.04 LTS as the base virtualization host and then an Intel Xeon CPU
> and two Nvidia GeForce GTX 750's as GPU's for the virtual machines.
>
> I'm really new to this sort of GPU passthrough on KVM and am wondering
if
> anyone has any advice or has done this before?
>
> Thank you!
>
>
>
>
> _______________________________________________
> libvirt-users mailing list
> libvirt-users@redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users

GizmoChicken,

Read that there's a problem with Nvidia GeForce GTX cards and both Xen and
KVM, like it's not on a Nvidia whitelist, I'm a bit concerned.  From the
ArchLinux thread I've seen some success with Nvidia GeForce GTX cards, this
is confusing.  The bit I read here was:

" That would mean you are stuck with the GTX for that, but Nvidia nerfs
their cards to stop passthrough, attempting to force you to pay for a
special card that allows it, costing in the neighborhood of like 2000$ for
a cheap one. "
http://www.reddit.com/r/linux/comments/23lpa6/question_where_are_we_with_video_card_passthrough/

Do I need a Quadro for this?  In that case it would be impossible to
justify.  Originally the GeForce GTX 750 Ti seemed like the ideal card for
this type of deployment.  Now I'm wondering if AMD is safer for the VDI
guest.  What should I do?

CC'd Alex Williamson into the thread so we can get some verification here
that Nvidia GeForce GTX are in fact able to do VGA passthrough with a stock
Fedora 20 virtualization host using VFIO with a KVM hypervisor.

Thanks.

On Sat, Oct 4, 2014 at 5:13 PM, Gizmo Chicken <gizmochicken@gmail.com>
wrote:
> Hi Alex,
>
> The first bit of advice that I was about to give was that you should
> have a look at a particular thread on the Arch Linux user forum.  But
> as it turns out, the article that you found (which seems really
> well-written) already mentions that thread, and in fact even links to
> one of my comments on that thread, namely this comment:
> https://bbs.archlinux.org/viewtopic.php?pid=1313007#p1313007
>
> With regard to CentOS 7 vs Ubuntu 14.04, keep in mind that VFIO (which
> is part of the Linux kernel) is relatively new and is still rapidly
> evolving.
>
> I'm not very familiar with CentOS, but if I'm not mistaken, CentOS
7
> uses kernel 3.10 by default.  You'll probably want to use a newer
> kernel version, which would have better VFIO support.  Again, I'm not
> really familiar with CentOS, but my understanding is that many feel
> that updating the kernel in CentOS isn't a good idea. So with this in
> mind, you might be better off using a distro that ships with a newer
> kernel version, such as Fedora or Ubuntu, etc.
>
> In my experience, Ubuntu 14.04, which ships with kernel 3.13 and QEMU
> 2.0, works pretty well with VFIO.  However, Ubuntu 14.10, which will
> ship with kernel 3.16 and QEMU 2.1, seems to work a little better, but
> is still pre-release and so has a few other bugs.  If you go with
> Ubuntu 14.04, you might want to install a newer "mainline"
kernel.
> But in any case, please do keep in mind that VFIO is still new and so
> you will almost assuredly encounter some bugs.  So don't expect 100%
> stability.
>
> Hope the above is of some help.
>
> Regards,
> GizmoChicken
>
> On Fri, Oct 3, 2014 at 5:19 PM, Alex G.S. <alxgrtnstrngl@gmail.com>
wrote:
> > Dear List,
> >
> > Recently I read an article [1] about how to use KVM and VGA
passthrough
> to
> > create multiple GPU accelerated VM's for use in gaming or as
virtual
> > workstations:
> >
> > [1]
> >
>
http://www.pugetsystems.com/labs/articles/Multiheaded-NVIDIA-Gaming-using-Ubuntu-14-04-KVM-585/
> >
> > I'm planning on building a KVM workstation to do this using CentOS
7 or
> > Ubuntu 14.04 LTS as the base virtualization host and then an Intel
Xeon
> CPU
> > and two Nvidia GeForce GTX 750's as GPU's for the virtual
machines.
> >
> > I'm really new to this sort of GPU passthrough on KVM and am
wondering if
> > anyone has any advice or has done this before?
> >
> > Thank you!
> >
> >
> >
> >
> > _______________________________________________
> > libvirt-users mailing list
> > libvirt-users@redhat.com
> > https://www.redhat.com/mailman/listinfo/libvirt-users
>