[vfio-users] Minimal host with desktop guest and gaming guest. Is this possible?

[Alex Williamson]

On Sat, Jul 15, 2017 at 7:17 PM, Nick Sarnie <commendsarnex at gmail.com>
wrote:

> On Sat, Jul 15, 2017 at 8:59 PM, almer <almertje at gmail.com> wrote:
> > Hi,
> >
> > my motivation: wattage concerns and not utilizing my hardware to the
> > fullest. My setup is pretty much historically grown to 3 computers now.
> one
> > for gaming (win10), one for storage/backup (debian stable) and one for
> > desktop (latest xubuntu). And the desktop hardware is quite old and
> weak, so
> > it bugs me that the good hardware is "wasted" on a windows system for
> games
> > only.
> > also with the next hardware purchase I would have to buy win10 because
> the
> > free w10 upgrade from w7 will break. the short version: I won't buy w10
> and
> > have decided to switch to wine/steam-OS gaming. ditching windows
> completely,
> > nearly all games that I play, run out of the box in wine/steam anyway.
> >
> > I've read that some setups utilize two graphics cards or IGP with a
> graphics
> > card. Now I was wondering if both setups could be combined. A minimal
> stable
> > distribution host for storage and providing what ever is needed for the
> > guests on the IGP. first guest stable desktop for daily desktop needs and
> > work with a passive graphics card for example a GT 710 passed through.
> > second guest a more current distribution as wine/steam gaming guest with
> a
> > more beefy graphics card passed through.
> >
> > Is this even possible? besides audio and mic config witch could get
> tricky I
> > presume and keyboard+mouse for 3 systems.
> >
> > My hardware pick so far:
> > - i5-7600k; mainly because of IGP, providing the 3. graphics card for the
> > host.
> > - ASUS Nvidia passive GT 710 and ASUS Nvidia GTX 1050 Ti STRIX for the
> two
> > guests; Nvidia because I read that AMD has PCIE reset issues and I would
> > like to stop and start guests with the PCIE cards more freely, without
> host
> > reboots.
> > - ASRock z270 Taichi; provides enough sata and usb for the storage/backup
> > needs.
>

Yes, it's possible, not even hard.  I've migrated my old desktop system to
a VM, so I boot from a USB stick, the host owns the disk controller, USB3
port, and NIC.  My Linux desktop get the IGD and the onboard USB
controllers, a Windows VM gets a GeForce 750 and a plugin USB3 card.  Why
not make more use of IGD assignment in your configuration.  Intel should be
supporting vGPU on KabyLake soon (of course they're not driving physical
monitors with vGPU yet).  Concerns with your hardware choice otherwise: a)
No ACS, you won't be able to assign cards in CPU root port slots to
separate VMs (see vfio.blogspot.com), b) insufficient cores, how much are
you willing to have your storage server interfere with your gaming
performance?


> I believe only the AMD RX 200-300 have the reset issue, and only some
> cards at that. My RX480 works fine. Also, if you plan to used the
> closed source nvidia drivers, I heard you can't unbind cards or unload
> the module, so you would have to reboot. Someone who has first hand
> experience should confirm. AMDGPU unloads and unbinds cards fine. No
> idea about nouveau.
>

So much FUD...  If you have a minimal host, why would you use the nvidia
driver in the host?  AMD Bonaire and Hawaii have known reset issues, nearby
generations have been reported to exhibit similar problems, but AMD denies
there's a hardware issue on those.  It's difficult to categorize these as
200-300 marketing IDs with the way AMD recycles cores.  NVIDIA has issues
with hypervisor detection, for which there are workarounds until NVIDIA
decides otherwise, AMD has undiagnosed performance issues, for which the
workaround cripples VM performance.  Pick your poison.  Thanks,

Alex
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