Bug#1120542: linux-image-6.12.48+deb13-cloud-amd64: vTPM failed to initialize on Google Compute Engine SEV and TDX Confidentail VMs

Package: src:linux
Version: 6.12.48-1
Severity: important
X-Debbugs-Cc: [email protected], [email protected]
User: [email protected]
Usertags: amd64

Dear Maintainer,

vTPM devices are failing to initialize on Debian 13. This is a regression compared to Debian 12, which is based on older kernel and is not affected.
This causes the attestation process to fail on Confidential VM running Debian 13.
A part of kernel log related to this issue is provided below.

The root cause is an upstream Linux kernel patch (commit# 8e690b817e38) first included in kernel v6.12, which changed the default memory caching mode for SEV-SNP and TDX and caused vTPM initialization to fail.
A fix for this regression has been merged upstream and will be included in v6.18 kernel.

We suggest Debian maintainers to either:

1. Revert the problematic patch (8e690b817e38) in the Debian 13 kernel. or
2. Backport the fix from upstream v6.18 to the Debian 13 kernel.


Korakit Seemakhupt


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-- Package-specific info:
** Version:
Linux version 6.12.48+deb13-cloud-amd64 ([email protected]) (x86_64-linux-gnu-gcc-14 (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44) #1 SMP PREEMPT_DYNAMIC Debian 6.12.48-1 (2025-09-20)

** Kernel log:
[    2.162450] ioremap error for 0xfed40000-0xfed45000, requested 0x2, got 0x0 
[    2.169640] tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -12