[vfio-users] VIFO in Intel Graphics Not working

[Alex Williamson]

On Tue, 08 May 2018 21:21:29 +0200
Chris <kaspro at web.de> wrote:
> # cat /etc/modprobe.d/vfio.conf
> options vfio-pci ids=8086:1902
> options vfio-pci disable_vga=1

VGA support is required for legacy mode IGD assignment, why is it being
disabled?

> # cat /etc/modprobe.d/blacklist.conf
> blacklist i915
> 
> # dracut -f /boot/initramfs-4.16.5-300.fc28.x86_64.img 4.16.5-300.fc28.x86_64
> # reboot
> # dmesg | grep -e DMAR -e IOMMU
> Kernel command line: BOOT_IMAGE=/vmlinuz-4.16.5-300.fc28.x86_64 root=/dev/mapper/fedora-root00 ro rd.lvm.lv=fedora/root00 rd.lvm.lv=fedora/swap rhgb quiet LANG=en_US.UTF-8 intel_iommu=on rd.driver.pre=vfio-pci bochs_drm.fbdev=off video=efifb:off,vesa:off,vesafb:off vga=normal iommu=no-igfx

Disabling the IOMMU for igfx when you're trying to use the IOMMU to
assign igfx seems like a bad idea, but luckily the option would have
been intel_iommu=igfx_off so the option was wrong on both ends.

> 3.: Configuring a guest with UEFI BIOS, 440FX Chipset gives (and thousands of these... not just some): 
> [ 3419.435439] DMAR: DRHD: handling fault status reg 2 
> [ 3419.435446] DMAR: [DMA Write] Request device [00:02.0] fault addr 0 [fault reason 02] Present bit in context entry is clear 
> [ 3419.436683] DMAR: DRHD: handling fault status reg 3 
> [ 3419.436691] DMAR: [DMA Read] Request device [00:02.0] fault addr afa40000 [fault reason 06] PTE Read access is not set 
> [ 3419.438069] DMAR: DRHD: handling fault status reg 3 
> [ 3419.438076] DMAR: [DMA Read] Request device [00:02.0] fault addr afa40000 [fault reason 06] PTE Read access is not set 
> [ 3419.439473] DMAR: DRHD: handling fault status reg 3 
> [ 3419.439480] DMAR: [DMA Read] Request device [00:02.0] fault addr afa6e000 [fault reason 06] PTE Read access is not set 
> [ 3419.440872] DMAR: DRHD: handling fault status reg 3 
> [ 3419.440879] DMAR: [DMA Read] Request device [00:02.0] fault addr afaa6000 [fault reason 06] PTE Read access is not set

This is what happens when the VBIOS tries to use the host stolen memory
because the quirks are disabled because QEMU doesn't have access to VGA
regions.  Thanks,

Alex