[SOLVED] Intel GVT-g: can't assign more than one 5_4 mdev

[kvn1351]

Hi, I've been stuck on this for almost an entire day now...

The documentation in regards to GVT-g isn't that abundant. I expected to be able to use at least two i915-GVTg_V5_4 vGPUs. Instead, I'm only able to use 1
V5_4 or 2 V5_8. The resulting performance in my two VMs is thus absolutely terrible.

I've also seen that others have more supported mdev types (like on the arch page):

# ls /sys/devices/pci${GVT_DOM}/$GVT_PCI/mdev_supported_types
i915-GVTg_V5_1
i915-GVTg_V5_2
i915-GVTg_V5_4
i915-GVTg_V5_8

Instead, all I get are these:

root@prox:~# ls /sys/devices/pci0000:00/0000:00:02.0/mdev_supported_types
i915-GVTg_V5_4
i915-GVTg_V5_8

So what am I missing here? Am I really just supposed to have one single V5_4 available?

Info​

CPU: Intel 10400

root@prox:~# apt show qemu-system-x86
Package: qemu-system-x86
Version: 1:3.1+dfsg-8+deb10u8

Kernel Version: Linux 5.4.106-1-pve #1 SMP PVE 5.4.106-1 (Fri, 19 Mar 2021 11:08:47 +0100)

I've been following these guides/docs:
https://cetteup.com/216/how-to-use-...rdware-accelerated-streaming-in-a-proxmox-vm/
https://wiki.archlinux.org/index.php/Intel_GVT-g

root@prox:~# cat /etc/default/grub
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="Proxmox Virtual Environment"
#GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on i915.enable_gvt=1 drm.debug=0"
GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on i915.enable_dc=0 i915.enable_guc=0 i915.enable_gvt=1 kvm.ignore_msrs=1 kvm.report_ignored_msrs=0"
GRUB_CMDLINE_LINUX=""

# Disable os-prober, it might add menu entries for each guest
GRUB_DISABLE_OS_PROBER=true

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Disable generation of recovery mode menu entries
GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

root@prox:~# cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.

# Modules required for PCI passthrough
vfio
vfio_iommu_type1
vfio_pci
vfio_virqfd

# Modules required for Intel GVT
kvmgt
exngt
vfio-mdev

root@prox:~# ls /sys/bus/pci/devices/0000:00:02.0
00000000-0000-0000-0000-000000000100  current_link_speed  drm            index          local_cpus            numa_node  resource2         subsystem_vendor
ari_enabled                           current_link_width  enable         iommu          max_link_speed        power      resource2_wc      uevent
boot_vga                              d3cold_allowed      firmware_node  iommu_group    max_link_width        remove     resource4         vendor
broken_parity_status                  device              gvt_firmware   irq            mdev_supported_types  rescan     revision
class                                 dma_mask_bits       i2c-0          label          modalias              reset      rom
config                                driver              i2c-1          link           msi_bus               resource   subsystem
consistent_dma_mask_bits              driver_override     i2c-2          local_cpulist  msi_irqs              resource0  subsystem_device

00000000-0000-0000-0000-000000000100 is the UUID of the only 5_4 vGPU I'm able to assign.

I'd be very grateful for any kind of help.

Have a nice day,
Kev

 

[dcsapak]

what is the reason you expected to use 2 V5_4 devices? these values are given by the kernel driver/hardware and is not really something we can change
what can play a role is the assigned video memory (in the bios)

also a newer kernel (for testing 5.11 is available) could help here

 

[kvn1351]

I found the issue. It was video memory-related indeed. I fixed it increasing the aperture size. Since my BIOS didn't have this option I had to find the offset and set it with a modified GRUB shell.

I've documented the proceedings here:
https://github.com/intel/gvt-linux/issues/131#issuecomment-815362316

Thanks.

 

[wrgoababd]

I found the issue. It was video memory-related indeed. I fixed it increasing the aperture size. Since my BIOS didn't have this option I had to find the offset and set it with a modified GRUB shell.

I've documented the proceedings here:
https://github.com/intel/gvt-linux/issues/131#issuecomment-815362316

Thanks.

Hello. Could you tell me how to find out these values for the motherboard? I’ve looked at your links, downloaded UEFITool, ran it on my computer, but it doesn’t respond to commands and doesn’t create a bios dump. Maybe there are links to instructions on how to use these tools? Google didn’t help me, or I searched poorly.