x86/cpu: Warn louder about the {set,clear}cpuid boot parameters

Browse source

Commit 814165e9fd ("x86/cpu: Add the 'setcpuid=' boot parameter")
recently expanded the user's ability to break their system horribly by
overriding effective CPU flags. This was reflected with updates to the
documentation to try and make people aware that this is dangerous.

To further reduce the risk of users mistaking this for a "real feature",
and try to help them figure out why their kernel is tainted if they do
use it:

- Upgrade the existing printk to pr_warn, to help ensure kernel logs
  reflect what changes are in effect.

- Print an extra warning that tries to be as dramatic as possible, while
  also highlighting the fact that it tainted the kernel.

Suggested-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250303-setcpuid-taint-louder-v1-2-8d255032cb4c@google.com

...

This commit is contained in:

Brendan Jackman 2025-03-03 15:45:38 +00:00 • committed by Ingo Molnar

parent 27c3b452c1

commit 681955761b

1 changed files with 12 additions and 7 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

19

arch/x86/kernel/cpu/common.c

View file