[vfio-users] vga pass-thru and different gfx cards.

[Torbjorn Jansson]

Hello all.

first of all a big thanks to alex willamsons and his blog series about 
getting a graphic card passed thru to a vm.
without those i wouldn't have been able to get it to work (more or less)

first some hw info about my linux box where i'm using vfio & kvm:
asus p8Z77-v le with 16gb ram and at the moment i'm using a nvidia gt610 
card from asus but i have also tried a gtx570.

i got it to work after a bit of reading alex blogs and a lot of testing.
i use the built in intel gfx card for the host since that is no good for 
anything else and the gt610 is passed thru to a win7 vm.

first problem i have is that vga pass-thru only works one time after a 
cold boot.
if i try to restart the vm or just power it of and on again i get a hard 
lockup of the host.
this is the most annoying problem.

the second problem is because the gt610 and gtx570 don't have any uefi 
bios i am forced to use plain vga pass-thru and i have to use the vgaarb 
patch to get it to work at all.
the problem (well, not really a problem but more of an extra 
complication) with this is that i have to manually patch and compile a 
new kernel.
it also disables vaapi/vdpau on the host and i use the hosts gfx card 
where having those still working would have been beneficial.


my questions:
i assume that it is the old vga pass thru and not uefi vbios (gop?) that 
contributes to the reboot problems, is that correct?
at least with uefi i assume i would be able to get rid of the vgaarb 
patch fixing vaapi/vdpau support.

if i bought another gfx card for vm pass-thru how would an uefi card 
improve things? (gt720 for example)
and would for example one of the not so expensive quadro cards like k420 
fix a few more issues? like the nvidia driver check for visualization.

i assume the k420 have the highest probability of just working and 
getting rid of the most issues, what is not clear is if k420 also have 
uefi support.

one annoying thing is that my asus gt610 card is supposed to be 
upgradable to uefi via a download tool from asus, but this doesnt work.
first issue i had was it only worked on asus mainboard, luckily my linux 
box had an asus mainboard so i had to temporarily put in a new disk and 
install windows to test the upgrade tool, but it still failed but now on 
the gfx card and just said contact support.