x86/bugs: Fix CONFIG_MITIGATION_RETPOLINE=n mitigation reporting

When the kernel lacks retpoline support, spectre_v2_select_retpoline()
emits

  "Kernel not compiled with retpoline; no mitigation available!"

before returning SPECTRE_V2_NONE to its callers.  SPECTRE_V2_NONE is not
the final answer, though: spectre_v2_update_mitigation() runs afterwards
and can still upgrade the mitigation.

On an Intel CPU affected by RETBleed, built with

  CONFIG_MITIGATION_IBRS_ENTRY=y and
  CONFIG_MITIGATION_RETPOLINE=n,

and booted with spectre_v2=auto, retbleed_select_mitigation() picks
RETBLEED_MITIGATION_IBRS, and spectre_v2_update_mitigation() then promotes
SPECTRE_V2_NONE to SPECTRE_V2_IBRS.  The boot log claims no mitigation is
available immediately before reporting

  "Spectre V2 : Mitigation: IBRS",

and sysfs reports the machine as mitigated.  The message is alarming and
simply wrong.

Drop "no mitigation available!" because the final mitigation state is printed
afterwards in spectre_v2_update_mitigation() anyway.

  [ bp: Drop CC:stable, massage commit message. ]

Fixes: 480e803dacf8 ("x86/bugs: Restructure spectre_v2 mitigation")
Suggested-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Assisted-by: LLM
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Link: https://patch.msgid.link/20260831210916.987152-1-kim.phillips@amd.com

0 files changed, 0 insertions, 0 deletions