Bug#1110722: linux: v6.12.35..v6.12.39 fail PCI (vfio) passthrough
Source: linux
Version: 6.12.38
Severity: important
Tags: upstream
X-Debbugs-Cc: tj.iam.tj@proton.me
Trixie 13.0 installer contains kernel version v6.12.38. This contains a
bug that breaks PCI passthrough (vfio) for VM guests. Symptoms will
depend on what is passed through.
On reboot into a Trixe VM that relies on passthrough it may fail in many
ways:
For GPUs the (PCI) gpu driver will fail to initialise the device
For storage devices and/or host bus adapters, they will fail to
initialise. If root file-system is on the storage device boot will fail,
dropping into the initialramfs shell reporting "root device X not
found".
For network devices there will be no interfaces.
Similar for USB and any other device passed through.
If the VM guest is using virtIO then many expected functions such as
keyboard may not work.
The problem was a backported commit in v6.12.35 that had one hunk applied in the wrong
function. That is:
fb5873b779dd "iommu/vt-d: Restore context entry setup order for aliased devices"
The fix in v6.12.40 is:
ff7ccaadb0bf "iommu/vt-d: Fix misplaced domain_attached assignment"
Reply to: