[vfio-users] pci passthrough of Intel igp

[daggs]

Greetings Alex,

> Sent: Wednesday, August 12, 2020 at 8:04 PM
> From: "Alex Williamson" <alex.williamson at redhat.com>
> To: "Patrick O'Callaghan" <poc at usb.ve>
> Cc: vfio-users at redhat.com, "daggs" <daggs at gmx.com>
> Subject: Re: [vfio-users] pci passthrough of Intel igp
>
> On Wed, 12 Aug 2020 17:46:33 +0100
> "Patrick O'Callaghan" <poc at usb.ve> wrote:
>
> > On Wed, 2020-08-12 at 18:02 +0200, daggs wrote:
> > > Greetings,
> > >
> > > I have a machine with an Intel igp of HD Graphics 610 [8086:5902].
> > > I found several discussions on the subject stating that it isn't possible but all of them are several years old.
> > > so I wanted to know if it is possible to pass it to a vm?
> > > I'm using kernel 5.4.43, libvirt-6.6.0 and qemu-5.0.0.
> >
> > If this is your only GPU, it doesn't make much sense. The idea of
> > passthrough is to let the VM control an additional GPU, not the main
> > one.
>
> There are plenty of people trying to assign their primary graphics
> device, it makes perfect sense for someone that doesn't intend to run a
> graphical environment on the host.  Assigning the primary GPU can be
> more challenging, but that doesn't mean it isn't done.
>
> For daggs, I can only say try it yourself, I don't know of any specific
> reason it wouldn't work, but direct assignment of IGD is a fair bit of
> luck anyway since the hardware is constantly changing and we don't
> really keep up with it.  You might need to play with the x-igd-gms
> value on the vfio-pci device in QEMU, several people have found that
> x-igd-gms=1 is necessary on some versions of hardware.  Thanks,
>
> Alex
>
>

I'm trying to boot the vm up with the igd pass-through, here is my xml: https://dpaste.com/CNDHRLNXC
the boot ends up with no signal and this is visible in dmesg:
[   36.181635] DMAR: DRHD: handling fault status reg 3
[   36.181641] DMAR: [DMA Read] Request device [00:02.0] PASID ffffffff fault addr c6000000 [fault reason 06] PTE Read access is not set
[   36.182298] DMAR: DRHD: handling fault status reg 3
[   36.182304] DMAR: [DMA Read] Request device [00:02.0] PASID ffffffff fault addr c603d000 [fault reason 06] PTE Read access is not set
[   36.183459] DMAR: DRHD: handling fault status reg 3
[   36.183464] DMAR: [DMA Read] Request device [00:02.0] PASID ffffffff fault addr c603e000 [fault reason 06] PTE Read access is not set
[   36.184614] DMAR: DRHD: handling fault status reg 3
[   36.721979] vfio-pci 0000:00:02.0: vfio_ecap_init: hiding ecap 0x1b at 0x100

I've dumped the rom, do I need to run the fixer on it? if so, what is the vid and did?
than I need to place this <rom file='/home/streamer/vga.rom'/> in the hostdev section?
I've noticed most of the reports say it works only on i440fx but they are all a few years old, is that still the case?

as part of this contexts, I have this in the kernel cmdline: pcie_acs_override=id:8086:a170 does it means device 8086:a170 is "broken" out of the iommu table?

Thanks,

Dagg.