Hi,
I'm getting ring 0 stalls and GPU lockups errors in the radeon driver
when starting Xorg. When passing through a AMD Radeon 7750 using VFIO.,
the display looks garbled with random-looking patterns and colors. The
guest tries to reset the GPU for a few seconds, until the host freezes
to the point where the reset button does not even work.
Passthrough of other devices such as on-board audio, USB3 controller
work fine with VFIO and linux guests. I have a VM that runs Fedora 21
and works fine on a kernel 2.6.32 (RedHat+OpenVZ+Proxmox) using
pci-assign. The same VM experiences the ring 0 stall, GPU lockup and a
host freeze with kernel 4.4.21 (Ubuntu+Proxmox) using vfio-pci.
The differences in kvm command-line parameters are:
Linux 2.6.32 + QEMU 2.2.1: -cpu SandyBridge,+x2apic
-device
'pci-assign,host=01:00.0,id=hostpci0.0,bus=ich9-pcie-port-1,addr=0x0.0,multifunction=on'
-device
'pci-assign,host=01:00.1,id=hostpci0.1,bus=ich9-pcie-port-1,addr=0x0.1'
-device 'pci-assign,host=00:1b.0,id=hostpci1,bus=pci.0,addr=0x11'
Linux 4.4.21 + QEMU 2.7.0: -cpu
'SandyBridge,+kvm_pv_unhalt,+kvm_pv_eoi,enforce,vendor=GenuineIntel'
-device
'vfio-pci,host=01:00.0,id=hostpci0.0,bus=ich9-pcie-port-1,addr=0x0.0,multifunction=on'
-device
'vfio-pci,host=01:00.1,id=hostpci0.1,bus=ich9-pcie-port-1,addr=0x0.1'
-device 'vfio-pci,host=00:1b.0,id=hostpci1,bus=pci.0,addr=0x11'
I have tried to use the same kvm command-line in 4.4, but it complains
about an invalid argument for hostpci0.0 and I cannot find out which or
why. (It also does not support +x2apic anymore)
I have tested also SeaBIOS (as secondary VGA) and OVMF (with single
x-vga=1) using Ubuntu Gnome 16.10, using machine q35 because the radeon
driver assumes a PCIE root, with the same results. According to lspci,
MSI-X is enabled. I have tried various kernel module settings for radeon
and vfio-pci that I found on this mailinglist to no avail
(radeon.hard_reset=1, .dpm=1, ..., vfio-pci.disable_idle_d3).
Has someone experienced similar issues and found a fix for it? Can
someone advise me on things to investigate or try to get my desktop VM
running with VFIO (or how to fall-back to pci-assign)?
I noticed people having more luck with NVidia, but I replaced mine with
AMD because I could get it to work with pci-assign some years back, and
would like to keep using open-source drivers.
Thank you and kind regards,
Arjen
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