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matthewmajf
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PostPosted: Tue Jul 02, 2024 5:31 pm    Post subject: Cannot create a mediated device with GVT-g... Reply with quote

As my laptop does not have two GPUs, and only one integrated graphics card, I am not able to just passthrough my integrated graphics card [to VMs], especially since I use several virtual machines in which I would normally passthrough multiple vGPU(s) created by Intel's GVT-g technology.
Intel's GVT-g technology has worked successfully with me on several distros, such as Debian, Ubuntu, Arch, etc. However, on Gentoo, [so far], I have not been able to successfully set up GVT-g.
I've even followed many tutorials, including these:
https://blog.freebsd-days.com/2021/05/windows-10-on-linux-kvm-with-intel-gvt-g/
https://wiki.gentoo.org/wiki/User:Shunlir/Intel_GVT-g
So here's how I attempted to get GVT-g working:
1. I would get the Gentoo kernel sources using portage, and then select the kernel using `eselect`.
2. I would then go to `/usr/src/linux`, run `make menuconfig`, make no changes in the menu, and save the `.config` file.
3. After that, I would edit the `.config` file manually, using GNU Nano, and set the following values:
CONFIG_VFIO_MDEV=m
CONFIG_VFIO_IOMMU_TYPE1=m
CONFIG_INTEL_IOMMU=y
CONFIG_DRM_I915_GVT=y
CONFIG_DRM_I915_GVT_KVMGT=m
4. I would then run `make`, `make modules_install`, and `make install`.
5. After that, I'd edit `/etc/default/grub`, and add these kernel parameters to `GRUB_CMDLINE_LINUX_DEFAULT`, each:
intel_iommu=on
i915.enable_gvt=1
kvm.ignore_msrs=1
i915.enable_guc=0
In the end, my `/etc/default/grub` file looked like this:
Code:

    # Copyright 1999-2020 Gentoo Authors
    # Distributed under the terms of the GNU General Public License v2
    #
    # To populate all changes in this file you need to regenerate your
    # grub configuration file afterwards:
    #     'grub-mkconfig -o /boot/grub/grub.cfg'
    #
    # See the grub info page for documentation on possible variables and
    # their associated values.

    GRUB_DISTRIBUTOR="Gentoo"

    # Default menu entry
    #GRUB_DEFAULT=0

    # Boot the default entry this many seconds after the menu is displayed
    #GRUB_TIMEOUT=5
    #GRUB_TIMEOUT_STYLE=menu

    # Append parameters to the linux kernel command line
    GRUB_CMDLINE_LINUX=""
    #
    # Examples:
    #
    # Boot with network interface renaming disabled
    # GRUB_CMDLINE_LINUX="net.ifnames=0"
    #
    # Boot with systemd instead of sysvinit (openrc)
    # GRUB_CMDLINE_LINUX="init=/usr/lib/systemd/systemd"

    # Append parameters to the linux kernel command line for non-recovery entries
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash isolcpus=1,5,2,6,3,7 intel_iommu=on i915.enable_gvt=1 kvm.ignore_msrs=1 i915.enable_guc=0"

    # 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

    # Set to 'text' to force the Linux kernel to boot in normal text
    # mode, 'keep' to preserve the graphics mode set using
    # 'GRUB_GFXMODE', 'WIDTHxHEIGHT'['xDEPTH'] to set a particular
    # graphics mode, or a sequence of these separated by commas or
    # semicolons to try several modes in sequence.
    #GRUB_GFXPAYLOAD_LINUX=

    # Path to theme spec txt file.
    # The starfield is by default provided with use truetype.
    # NOTE: when enabling custom theme, ensure you have required font/etc.
    #GRUB_THEME="/boot/grub/themes/starfield/theme.txt"

    # Background image used on graphical terminal.
    # Can be in various bitmap formats.
    #GRUB_BACKGROUND="/boot/grub/mybackground.png"

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

    # Comment if you don't want GRUB to pass "root=PARTUUID=xxx" parameter to kernel
    GRUB_DISABLE_LINUX_PARTUUID=false

    # Uncomment to disable generation of recovery mode menu entries
    #GRUB_DISABLE_RECOVERY=true

    # Uncomment to disable generation of the submenu and put all choices on
    # the top-level menu.
    # Besides the visual affect of no sub menu, this makes navigation of the
    # menu easier for a user who can't see the screen.
    #GRUB_DISABLE_SUBMENU=y

    # Uncomment to play a tone when the main menu is displayed.
    # This is useful, for example, to allow users who can't see the screen
    # to know when they can make a choice on the menu.
    #GRUB_INIT_TUNE="60 800 1"
   

6. So I'd then reload the GRUB bootloader by running `grub-mkconfig -o /boot/grub/grub.cfg`.

I'd then reboot, and to my surprise, when I'd go to `/sys/bus/pci/devices/0000:00:02.0/` (yes, that's also the address of my integrated graphics card), and the `mdev_supported_types` directory/file was nowhere to be found.
Yes, `CONFIG_VFIO_DEVICE` wasn't edited, because it was already nowhere to be seen in the kernel's configuration. Why is this so? Am I just no longer able to create mediated devices for use with GVT-g? My laptop only has one Mini-PCIe slot, but that's for the WiFi card, and I don't think there's any dGPU out there that can fit into such a small slot.

If anyone knows how to fix this problem, I'd greatly appreciate it!
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Cruslan
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PostPosted: Tue Jul 02, 2024 10:31 pm    Post subject: Reply with quote

You have to create MDEV device again every reboot. Or you may need set a OpenRC or systemd service that runs commands for you.
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matthewmajf
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PostPosted: Tue Jul 02, 2024 10:39 pm    Post subject: Reply with quote

Cruslan wrote:
You have to create MDEV device again every reboot. Or you may need set a OpenRC or systemd service that runs commands for you.

No, no, I understand that, but here's the thing, I am not capable of creating this MDEV device because the `mdev_supported_types` directory doesn't even exist in the iGPU's directory (`/sys/bus/pci/devices/0000:00:02.0`)!
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Cruslan
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PostPosted: Tue Jul 02, 2024 10:43 pm    Post subject: Reply with quote

Are you sure about your iGPU supports GVT-g technology? Small percentage of Intel iGPU's supports them. I have to ask because you didn't mentioned your platform.
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matthewmajf
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PostPosted: Tue Jul 02, 2024 10:56 pm    Post subject: Reply with quote

Cruslan wrote:
Are you sure about your iGPU supports GVT-g technology? Small percentage of Intel iGPU's supports them. I have to ask because you didn't mentioned your platform.

Mine in fact does. When I previously ran the same laptop on a Debian system, I was capable of creating a few vGPUs using GVT-g.
Running `neofetch` returns the following for my iGPU:
Code:

Intel WhiskeyLake-U GT2 [UHD Graphics 620]
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pietinger
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PostPosted: Wed Jul 03, 2024 12:04 am    Post subject: Re: Cannot create a mediated device with GVT-g... Reply with quote

matthewmajf wrote:
[...]
2. I would then go to `/usr/src/linux`, run `make menuconfig`, make no changes in the menu, and save the `.config` file.
3. After that, I would edit the `.config` file manually, using GNU Nano, and set the following values:
CONFIG_VFIO_MDEV=m
CONFIG_VFIO_IOMMU_TYPE1=m
CONFIG_INTEL_IOMMU=y
CONFIG_DRM_I915_GVT=y
CONFIG_DRM_I915_GVT_KVMGT=m
4. I would then run `make`, `make modules_install`, and `make install`.
[...]

This does not work - you will miss too many options. Please read this short chapter:
https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/Manual_kernel_configuration#Never_edit_.config

... and - if you want - the whole article ... and then:
https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/Manual_Configuring_Kernel_Version_6.6
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pietinger
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PostPosted: Wed Jul 03, 2024 12:21 am    Post subject: Reply with quote

P.S.: Only one example: If you enable DRM_I915_GVT_KVMGT in "make menuconfig" it will automatically enable also:
Quote:
Selects: DRM_I915_GVT [=n] && KVM_EXTERNAL_WRITE_TRACKING [=n] && VFIO_MDEV [=n]

(look into the help of DRM_I915_GVT_KVMGT)
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kimchi_sg
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PostPosted: Wed Jul 03, 2024 12:46 am    Post subject: Re: Cannot create a mediated device with GVT-g... Reply with quote

matthewmajf wrote:

2. I would then go to `/usr/src/linux`, run `make menuconfig`, make no changes in the menu, and save the `.config` file.

This alone will almost certainly make your new kernel unusable, the default config is very inadequate for most users.
Quote:

3. After that, I would edit the `.config` file manually, using GNU Nano, and set the following values:
CONFIG_VFIO_MDEV=m
CONFIG_VFIO_IOMMU_TYPE1=m
CONFIG_INTEL_IOMMU=y
CONFIG_DRM_I915_GVT=y
CONFIG_DRM_I915_GVT_KVMGT=m

As pietinger said, this makes your new kernel 200% more not bootable.
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matthewmajf
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PostPosted: Wed Jul 03, 2024 1:13 am    Post subject: Re: Cannot create a mediated device with GVT-g... Reply with quote

kimchi_sg wrote:
matthewmajf wrote:

2. I would then go to `/usr/src/linux`, run `make menuconfig`, make no changes in the menu, and save the `.config` file.

This alone will almost certainly make your new kernel unusable, the default config is very inadequate for most users.
Quote:

3. After that, I would edit the `.config` file manually, using GNU Nano, and set the following values:
CONFIG_VFIO_MDEV=m
CONFIG_VFIO_IOMMU_TYPE1=m
CONFIG_INTEL_IOMMU=y
CONFIG_DRM_I915_GVT=y
CONFIG_DRM_I915_GVT_KVMGT=m

As pietinger said, this makes your new kernel 200% more not bootable.

Well, I've had no problem booting with the new kernel, however of course, the mediated device feature did not work with GVT-g. I'll go and read the article, see if I can re-configure it properly, and i'll report back here with some status once I'm done!

And thanks for all of the help, by the way.
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matthewmajf
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PostPosted: Wed Jul 03, 2024 4:46 pm    Post subject: Reply with quote

Alright, so I have been able to clean up the whole kernel, and used `make menuconfig` to enable the flags I mentioned in the post above. However, when I boot up, it seems that the GRUB bootloader reports that it's loading the initial ramdisk, however it hangs there.
So I ran `make menuconfig` again, and enabled simple framebuffer, and EFI framebuffer, however that didn't fix up anything. I'm guessing the system does boot, but cannot manage to display anything successfully, so I tried SSH'ing to my laptop from another computer, however I was not able to connect.
What am I doing wrong here?
Here's my `.config` file (no, I have not edited it manually):
https://pastebin.com/raw/4B9L00tz
Here's my `/etc/default/grub` file:
Code:

# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
#
# To populate all changes in this file you need to regenerate your
# grub configuration file afterwards:
#     'grub-mkconfig -o /boot/grub/grub.cfg'
#
# See the grub info page for documentation on possible variables and
# their associated values.

GRUB_DISTRIBUTOR="Gentoo"

# Default menu entry
#GRUB_DEFAULT=0

# Boot the default entry this many seconds after the menu is displayed
#GRUB_TIMEOUT=5
#GRUB_TIMEOUT_STYLE=menu

# Append parameters to the linux kernel command line
GRUB_CMDLINE_LINUX=""
#
# Examples:
#
# Boot with network interface renaming disabled
# GRUB_CMDLINE_LINUX="net.ifnames=0"
#
# Boot with systemd instead of sysvinit (openrc)
# GRUB_CMDLINE_LINUX="init=/usr/lib/systemd/systemd"

# Append parameters to the linux kernel command line for non-recovery entries
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash isolcpus=1,5,2,6,3,7 intel_iommu=on i915.enable_gvt=1 kvm.ignore_msrs=1"

# 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

# Set to 'text' to force the Linux kernel to boot in normal text
# mode, 'keep' to preserve the graphics mode set using
# 'GRUB_GFXMODE', 'WIDTHxHEIGHT'['xDEPTH'] to set a particular
# graphics mode, or a sequence of these separated by commas or
# semicolons to try several modes in sequence.
#GRUB_GFXPAYLOAD_LINUX=

# Path to theme spec txt file.
# The starfield is by default provided with use truetype.
# NOTE: when enabling custom theme, ensure you have required font/etc.
#GRUB_THEME="/boot/grub/themes/starfield/theme.txt"

# Background image used on graphical terminal.
# Can be in various bitmap formats.
#GRUB_BACKGROUND="/boot/grub/mybackground.png"

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

# Comment if you don't want GRUB to pass "root=PARTUUID=xxx" parameter to kernel
GRUB_DISABLE_LINUX_PARTUUID=false

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY=true

# Uncomment to disable generation of the submenu and put all choices on
# the top-level menu.
# Besides the visual affect of no sub menu, this makes navigation of the
# menu easier for a user who can't see the screen.
#GRUB_DISABLE_SUBMENU=y

# Uncomment to play a tone when the main menu is displayed.
# This is useful, for example, to allow users who can't see the screen
# to know when they can make a choice on the menu.
#GRUB_INIT_TUNE="60 800 1"

And here's the logs from running `make modules_install && make install`:
Code:

  SYMLINK /lib/modules/6.6.30-gentoo/build
  INSTALL /lib/modules/6.6.30-gentoo/modules.order
  INSTALL /lib/modules/6.6.30-gentoo/modules.builtin
  INSTALL /lib/modules/6.6.30-gentoo/modules.builtin.modinfo
  INSTALL /lib/modules/6.6.30-gentoo/kernel/fs/efivarfs/efivarfs.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/drivers/vfio/pci/vfio-pci-core.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/drivers/vfio/pci/vfio-pci.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/drivers/thermal/intel/x86_pkg_temp_thermal.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/netfilter/nf_log_syslog.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/netfilter/xt_mark.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/netfilter/xt_nat.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/netfilter/xt_LOG.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/netfilter/xt_MASQUERADE.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/netfilter/xt_addrtype.ko
  INSTALL /lib/modules/6.6.30-gentoo/kernel/net/ipv4/netfilter/iptable_nat.ko
  DEPMOD  /lib/modules/6.6.30-gentoo

https://pastebin.com/raw/dYVxX0NX
Anyone know why this is happening?
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pietinger
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PostPosted: Wed Jul 03, 2024 5:31 pm    Post subject: Reply with quote

You have not configured:
Code:
# CONFIG_FRAMEBUFFER_CONSOLE is not set

# CONFIG_DRM_FBDEV_EMULATION is not set

There is a reason I named the chapter "Must have" ...
https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/Manual_Configuring_Kernel_Version_6.6#Part_3_-_Must_Haves

(The same result you would have with doing a "make menuconfig" and saving it without any changes ... the default config does not have everything you need.)
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matthewmajf
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PostPosted: Thu Jul 04, 2024 3:44 pm    Post subject: Reply with quote

pietinger wrote:
You have not configured:
Code:
# CONFIG_FRAMEBUFFER_CONSOLE is not set

# CONFIG_DRM_FBDEV_EMULATION is not set

There is a reason I named the chapter "Must have" ...
https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/Manual_Configuring_Kernel_Version_6.6#Part_3_-_Must_Haves

(The same result you would have with doing a "make menuconfig" and saving it without any changes ... the default config does not have everything you need.)


This has seemed to fix the issue! I was able to enable framebuffer, and XFS support, getting my kernel to work.
I very much appreciate the help, thanks!
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pietinger
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PostPosted: Thu Jul 04, 2024 4:54 pm    Post subject: Reply with quote

matthewmajf wrote:
This has seemed to fix the issue! I was able to enable framebuffer, and XFS support, getting my kernel to work.

Happy to hear that. :D Does GVT-g also work now ?

matthewmajf wrote:
I very much appreciate the help, thanks!

You are very Welcome ! :D

Have fun with Gentoo ! 8)
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