[vfio-users] KVM + QEMU + GPU passthrough (Windows7 Guest)

[Okky Hendriansyah]

Hi Francisco,

It seems that you passthrough in VGA mode (x-vga=on) but you are using OVMF also. Have you tried omiting the x-vga=on switch?

Best regards,
-- 
Okky Hendriansyah
On September 23, 2015 at 11:05:44, Francisco Menendez (aterfelis at gmail.com) wrote:

I'm having a bit of an odd issue and would greatly appreciate it if  
someone has any clue as of what might be happening.  

The system:  
* Intel CPU with VTx and VTd enabled in BIOS  
* NVidia GTX 980 - isolated (vfio), to be used by the guest  
* Intel graphics for the host (Arch Linux x64)  

What I've done:  

* Added "iommu_intel=on" to the kernel boot command line  
* Blacklisted the nouveau driver  
* Added the vfio-pci driver and assigned the necessary ids (GPU +  
attached HDMI sound)  
* Confirmed IOMMU groups ( /sys/kernel/iommu_groups/ -type l output is OK)  
* Confirmed vfio-pci capture with dmesg  

What happens:  

After booting windows, I get the GPU displaying the "Starting Windows"  
splash screen, with animation and everything. Thus far, I think the  
GPU passthrough is successful. However, after that, the screen gets  
stuck there while the system keeps booting. I even hear the windows  
chime as it starts, but the screen is still showing "Starting Windows"  

If I use emulated VGA, the NVidia card shows "Code 12", but I hear  
this is expected if the emulated VGA is turned on.  

The above is also reproducible with the windows installer ( The GPU  
output displays: "Windows is loading files" -> "Starting windows" ->  
no more screen updates )  

QEMU commandline:  

--------------  
qemu-system-x86_64 \  
-name windows7 \  
-cpu host,kvm=off \  
-smp 8,sockets=1,cores=4,threads=2 \  
-enable-kvm \  
-machine type=pc,accel=kvm,iommu=on \  
-m 16G -mem-prealloc -balloon none \  
-rtc clock=host,base=utc \  
-soundhw hda \  
-device ioh3420,bus=pci.0,addr=1c.0,multifunction=on,port=1,chassis=1,id=root.1  
\  
-device vfio-pci,host=01:00.0,bus=root.1,addr=00.0,multifunction=on,x-vga=on \  
-device vfio-pci,host=01:00.1,bus=root.1,addr=00.1 \  
-drive if=pflash,format=raw,readonly,file=/usr/share/edk2.git/ovmf-x64/OVMF_CODE-pure-efi.fd  
\  
-drive if=pflash,format=raw,file=/usr/share/edk2.git/ovmf-x64/OVMF_VARS-pure-efi.fd  
\  
-drive file=win7.img,if=ide,format=raw,media=disk \  
-monitor stdio \  
-device piix3-usb-uhci -device usb-tablet \  
-vga none -serial null -parallel null -nodefaults -nodefconfig  
----------------  

Let me know if you need any other information about the setup.  
Thank you in advance!  

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