[vfio-users] help with choice of GPU for passthrough

[Alex Williamson]

On Mon, 2016-01-25 at 21:57 +0000, Bronek Kozicki wrote:
> I'm upgrading my home machine, it is running two Windows 7 VMs and they 
> need identical hardware configuration. The host is 2x Xeon E5-2667V2 + 
> 128GB RAM - obviously oversized for only two Windows ;-P . I'm 
> considering choice between Radeon Fury Nano and more expensive nVidia. I 
> know that Radeons have problem with PCIe reset (in kernel 4.1.15 + qemu 
> 2.4.1), is this likely to have been solved in a newer version I am not 
> using yet/not written yet?

No.

> If not, then I will consider switching to nVidia but the problem here is 
> the price, obviously. For the price only "little" higher than Nano I can 
> buy Quadro M4000 but Id rather have more performance. I wonder whether 
> nVidia played silly games disabling its drivers under vfio with Titan X 
> - that would be a very nice option. I do not want to spend more than 
> $1300 per card.
> 
> Any advice?

Nvidia hasn't caused any new problems lately and we've managed to
circumvent the whole hypervisor detection thing.  That doesn't mean
they couldn't re-enable it if they wanted to.  Unfortunately the only
supported route is the Quadro line and you pay for that support with
pricey cards with lower performance.  To be fair, Quadro has gotten
more affordable in the past few years, but it's certainly not tailored
for gaming... all the value they add with GeForce Experience is
missing.

AMD... every new generation seems to have have different issues.  Even
the Bonaire/Hawaii quirks is just barely a workaround.  I'm glad it
works as well as it does for people, but if you push it you'll be
forced to do a host reboot.  It seems like UEFI support on AMD is more
miss than hit as well.  My Bonaire card hangs the VM if I try to boot
with OVMF. The older 7700/7800 Radeon HD cards seem like relatively
good picks, modulo UEFI BIOS support, but probably aren't the
performance level you're after.

> PS Feel free to cite me to AMD support, they may possibly lose my brand 
> loyalty due to broken PCIe reset - I'm just too tired of not being able 
> to reliably reset my VMs. Even if I need to pay more for worse performance.

I've been told that AMD reset bugs can be filed here:

https://bugs.freedesktop.org

Product: DRI, component: DRM/Radeon or DRM/Amdgpu depending ASIC

Please, please, please don't go bombard them with a ton of bugs, don't
expect Windows driver support, and don't derail bugs with tangential
problems. I would say to focus on the reset problem, preferably on the
newer GPUs.  Thanks,

Alex