Re: [Xen-users] dedicated vga passthru problem with Intel igd at skylake

["G.R." <firemeteor@xxxxxxxxxxxxxxxxxxxxx>]

On Sat, Apr 13, 2019, 04:50 Oliver Rath <oliver@xxxxxxxxxxxx> wrote:

Hi list,

I try to passthrough the dedicate GPU (not a virtual part like xengt) to a xen DomU with Windows 10 (32bit) inside. Following the hints from the internet I try to passthrough the real Card as secondary to the internel qemu based gpu, but this gets an error:

# xl create /root/windows.cfg
Parsing config from /root/windows.cfg
libxl: error: libxl_qmp.c:341:qmp_handle_error_response: Domain 4:received an error message from QMP server: Need to enable igd-passthru if you're trying to passthrough IGD GFX
libxl: error: libxl_pci.c:1300:libxl__add_pcidevs: Domain 4:libxl_device_pci_add failed: -3
libxl: error: libxl_create.c:1575:domcreate_attach_devices: Domain 4:unable to add pci devices
libxl: error: libxl_domain.c:1038:libxl__destroy_domid: Domain 4:Non-existant domain
libxl: error: libxl_domain.c:993:domain_destroy_callback: Domain 4:Unable to destroy guest
libxl: error: libxl_domain.c:920:domain_destroy_cb: Domain 4:Destruction of domain failed

Starting the DomU with igd (or "1") as primary card starts without an error, but in the vnc-window stands: "Guest has not initialized the display (yet)" without change, so that I assume, that the vm freezes.

I had prior experience on building up igd passthrough long time ago, with a lot of patching... The build was broken when I moved to newer xen version without patch. But according to xen wiki recent versions should work. I wonder if it's because my HW is too old and has been excluded from the support list? It's a i7-3770 igd. In Debian stock xen4.14 I see the domU boots without any actual output nor any error. The syndrome looks like the op-region related issue that I solved with patch on qemu-traditional.

The bottom line, I think the blank vnc window could be normal. The system is probably running just fine. Try connecting through network (ping,rdp) to verify?

The configuration is:

type='hvm'
vcpus=4
memory = 4096
name = "win10"
vif = [ 'type=ioemu,bridge=xenbr0,model=e1000' ]
disk = ['/dev/dmivg/xen-win10,,hda,w','/root//Win10_1809Oct_German_x32.iso,,hdc,cdrom']
#disk = ['/dev/dmivg/xen-win10,raw,hda,w','/root/intel-gfx.iso,,hdc,cdrom']
device_model_version = 'qemu-xen'
device_model_override = '/usr/local/lib/xen/bin/qemu-system-i386'
boot="c"
#serial='pty'
localtime=1
vnc=1
gfx_passthru='1'
pci=['00:02.0,permissive=1']

The only difference is setting gfx_passthru="0" for starting the vm to install the intel gfx drivers. Setting this to "igd" resulted the same as "1".  Isolating the GPU via "xl pci-assignable-add 00:02.0" works fine. The machine is a i5-6400T CPU with this GPU only:

00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics 530 [8086:1912] (rev 06)

The result of

# xl pci-assignable-list
0000:00:02.0

Seems working with pciback module correctly.

I tried two different Configurations:

• Xen-4.12 with Vanilla Kernel 5.0.7
  
• Xen-4.10 with XenGT-Patches and Linux-4.17+ (including xengt kernel-modul) from xengt-sources

Both configurations got the same results.

Is it possible to passthrough this IGD VGA as dedicated card into xen? How can I install the drivers (setting igd to secondary)?

If you need more detailed information, please feel free to contact me!

Tfh!

Oliver

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