[pve-devel] [PATCH docs 0/3] pci-passthrough: update section for newer kernels, add mdev driver note

[pve-devel] [PATCH docs 0/3] pci-passthrough: update section for newer kernels, add mdev driver note

[Christoph Heiss]

#1 and #2 update the section w.r.t. to the current 6.8 kernels, dropping
some now-obsolete requirements for PCI passthrough.

#3 adds two small notes when passing through mediated devices, as these
work a bit differently than normal passthrough.

Noticed these things while testing out Dominik's Nvidia vGPU series [0].

[0] https://lore.proxmox.com/pve-devel/20240806122203.2266054-1-d.csapak@proxmox.com/

Christoph Heiss (3):
  pci-passthrough: drop obsolete `vfio_virqfd` kernel module requirement
  pci-passthrough: mention that `intel_iommu=on` is the default for 6.8+
  pci-passthrough: add note about mediated devices w.r.t kernel modules

 qm-pci-passthrough.adoc | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

-- 
2.46.0



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[pve-devel] [PATCH docs 1/3] pci-passthrough: drop obsolete `vfio_virqfd` kernel module requirement

[Christoph Heiss]

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
 qm-pci-passthrough.adoc | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
index 4cbaadd..c3dd184 100644
--- a/qm-pci-passthrough.adoc
+++ b/qm-pci-passthrough.adoc
@@ -92,17 +92,13 @@ to the xref:sysboot_edit_kernel_cmdline[kernel commandline].
 
 .Kernel Modules
 
-//TODO: remove `vfio_virqfd` stuff with eol of pve 7
 You have to make sure the following modules are loaded. This can be achieved by
-adding them to `'/etc/modules''. In kernels newer than 6.2 ({pve} 8 and onward)
-the 'vfio_virqfd' module is part of the 'vfio' module, therefore loading
-'vfio_virqfd' in {pve} 8 and newer is not necessary.
+adding them to `'/etc/modules''.
 
 ----
  vfio
  vfio_iommu_type1
  vfio_pci
- vfio_virqfd #not needed if on kernel 6.2 or newer
 ----
 
 [[qm_pci_passthrough_update_initramfs]]
-- 
2.46.0



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[pve-devel] [PATCH docs 2/3] pci-passthrough: mention that `intel_iommu=on` is the default for 6.8+

[Christoph Heiss]

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
 qm-pci-passthrough.adoc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
index c3dd184..70e33f2 100644
--- a/qm-pci-passthrough.adoc
+++ b/qm-pci-passthrough.adoc
@@ -74,7 +74,8 @@ xref:sysboot_edit_kernel_cmdline[kernel command line] kernels by adding:
  intel_iommu=on
 ----
 
-For AMD CPUs it should be enabled automatically.
+For AMD CPUs it should be enabled automatically. For Intel CPUs this is also
+the default since the 6.8 kernel series.
 
 .IOMMU Passthrough Mode
 
-- 
2.46.0



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Re: [pve-devel] [PATCH docs 2/3] pci-passthrough: mention that `intel_iommu=on` is the default for 6.8+

[Aaron Lauterer]

Looking at the surrounding context, I would rework this section even 
more. Before I just apply my approach, what do you think about the 
following change?
---
diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
index 4f19f2a..ca07692 100644
--- a/qm-pci-passthrough.adoc
+++ b/qm-pci-passthrough.adoc
@@ -63,19 +63,18 @@ some configuration to enable PCI(e) passthrough.

  .IOMMU

-First, you will have to enable IOMMU support in your BIOS/UEFI. Usually the
+You will have to enable IOMMU support in your BIOS/UEFI. Usually the
  corresponding setting is called `IOMMU` or `VT-d`, but you should find 
the exact
  option name in the manual of your motherboard.

-For Intel CPUs, you also need to enable the IOMMU on the
-xref:sysboot_edit_kernel_cmdline[kernel command line] kernels by adding:
+With recent kernels (6.8 or newer), `IOMMU` should be enabled 
automatically.
+On older kernels, it was necessary to enable it on Intel CPUs via the
+xref:sysboot_edit_kernel_cmdline[kernel command line] by adding:

  ----
   intel_iommu=on
  ----

-For AMD CPUs it should be enabled automatically.
-
  .IOMMU Passthrough Mode

  If your hardware supports IOMMU passthrough mode, enabling this mode might



On  2024-10-22  12:19, Christoph Heiss wrote:
> Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
> ---
>   qm-pci-passthrough.adoc | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
> index c3dd184..70e33f2 100644
> --- a/qm-pci-passthrough.adoc
> +++ b/qm-pci-passthrough.adoc
> @@ -74,7 +74,8 @@ xref:sysboot_edit_kernel_cmdline[kernel command line] kernels by adding:
>    intel_iommu=on
>   ----
>   
> -For AMD CPUs it should be enabled automatically.
> +For AMD CPUs it should be enabled automatically. For Intel CPUs this is also
> +the default since the 6.8 kernel series.
>   
>   .IOMMU Passthrough Mode
>   



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[pve-devel] [PATCH docs 3/3] pci-passthrough: add note about mediated devices w.r.t kernel modules

[Christoph Heiss]

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
 qm-pci-passthrough.adoc | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
index 70e33f2..ae0bdde 100644
--- a/qm-pci-passthrough.adoc
+++ b/qm-pci-passthrough.adoc
@@ -96,6 +96,14 @@ to the xref:sysboot_edit_kernel_cmdline[kernel commandline].
 You have to make sure the following modules are loaded. This can be achieved by
 adding them to `'/etc/modules''.
 
+.Mediated devices passthrough
+[NOTE]
+====
+If passing through mediated devices (e.g. vGPUs), the following is not needed.
+In these cases, the device will be owned by the appropriate host-driver
+directly.
+====
+
 ----
  vfio
  vfio_iommu_type1
@@ -274,6 +282,13 @@ Kernel driver in use: vfio-pci
 or the 'in use' line is missing entirely, the device is ready to be used for
 passthrough.
 
+.Mediated devices
+[NOTE]
+====
+For mediated devices this line will differ as the device will be owned as the
+host driver directly, not 'vfio-pci'.
+====
+
 [[qm_pci_passthrough_vm_config]]
 VM Configuration
 ^^^^^^^^^^^^^^^^
-- 
2.46.0



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