[vfio-users] Skylake IGD + Windows 10 VM = 4.3Gb of non paged memory

[mathieu at lesperance.cloud]

Thanks for your help ! 

I've added this to my Windows 10 XML config and the memory issue is gone:
  <qemu:commandline>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.x-igd-opregion=on'/>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.x-igd-gms=1'/>
  </qemu:commandline>

Regards, Mathieu

-----Message d'origine-----
De : Alex Williamson [mailto:alex.williamson at redhat.com] 
Envoyé : 7 octobre 2017 16:31
À : mathieu at lesperance.cloud
Cc : vfio-users at redhat.com
Objet : Re: [vfio-users] Skylake IGD + Windows 10 VM = 4.3Gb of non paged
memory

On Sat, 7 Oct 2017 15:37:32 -0400
<mathieu at lesperance.cloud> wrote:

> Hi folks,
> 
>  
> 
> I have a Windows 10 VM running on unRAID 6.3.5 which as KVM/QEMU 
> built-in (QEMU 2.7.1 / libvirt 2.4.0), which I passthrough a Skylake 
> IGD in legacy mode. The video output works fine, however, the issue is 
> that the intel video driver memory manager stole 4.3GB and put it in a 
> non-paged memory pool. That mean that on my 8GB of ram in my VM, only 
> 3.7GB is available to the user. If I assign less than 4GB, the intel IGD
wont work at all.
> 
>  
> 
> I've read about the fw_cfg that need some configuration for IGD, but I 
> didn't find any prebuild file for an IGD nor the source files to build 
> the binaries.
> 
>  
> 
> I have open threads in two other forum but no success so far: 
> 
>  
> 
> https://forums.lime-technology.com/topic/60107-635-passing-through-int
> el-igd -with-win10-abnormally-high-mem-usage/
> 
>  
> 
> https://communities.intel.com/thread/118393
> 
>  
> 
> Thanks for your help, Mathieu.

There are versions of the IGD Windows driver that freak out when they find
zero stolen memory reserved, the workaround is to add the parameter
x-igd-gms=1 to the parameter list for the device.  Intel has indicated that
they intend to fix this in the Windows driver, so updating to the latest
Intel driver release may also be enough to resolve it.  See:

https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg08092.html

Thanks,
Alex