[tip: x86/bugs] x86/bugs: Report correct retbleed mitigation status
From: tip-bot2 for David Kaplan
Date: Tue Sep 16 2025 - 08:54:41 EST
The following commit has been merged into the x86/bugs branch of tip:
Commit-ID: 930f2361fe542a00de9ce6070b1b6edb976f1165
Gitweb: https://git.kernel.org/tip/930f2361fe542a00de9ce6070b1b6edb976f1165
Author: David Kaplan <david.kaplan@xxxxxxx>
AuthorDate: Mon, 15 Sep 2025 08:47:06 -05:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Tue, 16 Sep 2025 13:32:18 +02:00
x86/bugs: Report correct retbleed mitigation status
On Intel CPUs, the default retbleed mitigation is IBRS/eIBRS but this
requires that a similar spectre_v2 mitigation is applied. If the user
selects a different spectre_v2 mitigation (like spectre_v2=retpoline) a
warning is printed but sysfs will still report 'Mitigation: IBRS' or
'Mitigation: Enhanced IBRS'. This is incorrect because retbleed is not
mitigated, and IBRS is not actually set.
Fix this by choosing RETBLEED_MITIGATION_NONE in this scenario so the
kernel correctly reports the system as vulnerable to retbleed.
Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/20250915134706.3201818-1-david.kaplan@xxxxxxx
---
arch/x86/kernel/cpu/bugs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 66dbb3b..6a526ae 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1462,8 +1462,10 @@ static void __init retbleed_update_mitigation(void)
retbleed_mitigation = RETBLEED_MITIGATION_EIBRS;
break;
default:
- if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF)
+ if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) {
pr_err(RETBLEED_INTEL_MSG);
+ retbleed_mitigation = RETBLEED_MITIGATION_NONE;
+ }
}
}